Notice: We are in the process of migrating Oral History Interview metadata to this new version of our website.
During this migration, the following fields associated with interviews may be incomplete: Institutions, Additional Persons, and Subjects. Our Browse Subjects feature is also affected by this migration.
Please contact [email protected] with any feedback.
This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics.
This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.
Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event. Disclaimer: This transcript was scanned from a typescript, introducing occasional spelling errors. The original typescript is available.
In footnotes or endnotes please cite AIP interviews like this:
Interview of Peter McIntyre by David Zierler on July 27 & August 2, 2020,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
In this interview, Peter McIntyre, Mitchell-Heep professor of experimental physics at Texas A&M University, and president of Accelerator Technology Corporation discusses his career and achievements as a professor. McIntyre recounts his childhood in Florida, and he explains his decision to pursue physics as an undergraduate at the University of Chicago and the influence of his longtime hero Enrico Fermi. He discusses his interests in experimental physics and he explains his decision to stay at Chicago for graduate school, where he worked with Val Teledgi, during a time he describes as the last days of bubble chamber physics. McIntyre conveys his intense opposition to the Vietnam War and the extreme lengths he took to avoid being drafted, and his dissertation work on the Ramsey resonance in zero field. He describes Telegdi’s encouragement for him to pursue postdoctoral research at CERN where he worked with Carlo Rubbia on the Intersecting Storage Rings project. He describes his time as an assistant professor at Harvard and his work at Fermilab, and the significance of his research which disproved Liouville’s theorem. McIntyre describes the series of events leading to his tenure at Texas A&M, and he explains how his hire fit into a larger plan to expand improve the physics program there. He discusses the completion of the Tevatron at Fermilab and the early hopes for the discovery of the mass scale of the Higgs boson, and he describes the origins of the SSC project in Texas and the mutually exclusive possibility that Congress would fund the International Space Station instead. McIntyre describes the key budgetary shortfalls that essentially doomed the SSC from the start, his efforts in Washington to keep the project viable, and the technical shortcomings stemming from miscommunication and stove-piping of expertise. He describes his involvement in the discovery of the top quark and the fundamental importance of the CDF, DZero, and ATLAS collaborations. McIntyre discusses his achievements as a teacher to undergraduates and a mentor to graduate students, and he assesses the current and future prospects for ongoing discovery in high energy physics. At the end of the interview, McIntyre describes his current wide-ranging research interests, including his efforts to improve the entire diagnostic infrastructure in screening and early detection of breast cancer.
Okay. This is David Zierler, oral historian for the American Institute of Physics. It is July 27th, 2020. It’s my great pleasure to be here with Professor Peter McIntyre. Peter, thank you so much for joining me today.
Okay, so to start, would you tell me your title and institutional affiliation?
Okay, my full name is Peter Mastin McIntyre III. I am the Mitchell-Heep professor of Experimental Physics at Texas A&M University. I also serve as President of Accelerator Technology Corp, which is a small for-profit company based here in College Station, Texas, to which I spin out a variety of technologies that I invent.
Now, I’m sorry that it’s only an audio transcript so that researchers cannot get a sense of this amazing backdrop that I’m looking at here. But just for some context, I just want to point out that Peter gave me a tremendous tour of his lab. Is there a name for the lab?
The Accelerator Research Lab.
And do you have a formal affiliation? Are you director? Is it just your lab?
Okay (laughter). Wonderful. Okay. So, let’s now, Peter, let’s take it back to the beginning. Let’s start with your parents. Tell me a little bit about your parents, and where they’re from.
Okay. I grew up in a small town called Clewiston, Florida. It is on the southern shore of Lake Okeechobee in the southern part of Florida. So, you can see that easily on a map of the state. It’s the second largest freshwater lake entirely within the United States. The only one larger is Lake Michigan. All the other great lakes are shared with Canada. It is a town that is known for growing sugarcane, and is—well, it proudly proclaims to be the bass fishing capital of America. There are something like 100 different towns around the United States that also vie for that title, and I wouldn’t dream of arguing the pros (laughter)- or cons. My father —by the same name as mine, except he was Junior—was the agricultural manager, the field manager of a sugarcane growers’ co-op, which is an interesting proposition. It was a collaboration of 50 or so farmers. Each of them had quite a bit of acreage, you know, anything from a few thousand to a few tens of thousands of acres that they had planted in sugarcane. And they had gotten together at a certain point to pool their money as an investment, and build their own refinery to make sugar, and go into competition with the several large corporate entities that were doing that already for many years in South Florida. And so his life was interesting.
The arguments had to come to his desk. And with him out into the field with the farmers because sugarcane, as it matures, the content of sugar in the juice of the cane grows through the season from a point where it’s just very slightly sweet to the tongue if you were to take a piece of it, peel it, and chew it, to where it’s extremely sweet. For well-bred sugarcane, it gets up to about 10% sugar content in the juice. So that process goes up a curve that you can sort of imagine, either as a physicist or a biologist, and reaches a certain peak on a certain day, usually just before the first freeze of the winter season, and then falls off fairly rapidly after that.
Well, as you can imagine, each of those 50 farmers was determined he wanted his cane harvested when its sugar content was at the peak. So, every one of the 50 was having him out in the field, taking a piece of their cane in, and having it tested for its sugar content, virtually every day. And then predictably, maybe 30 of the fields matured at the same time, and so then he had those farmers demanding to be the first, etc. So, he had an interesting life, you know, dealing with fairly cantankerous individuals.
My mother, Ruby, was a wonderful woman. Before I was born, she worked for the Army Corps of Engineers monitoring Lake Okeechobee in connection with their massive waterworks that they ran to do flood control. Long after I left Florida, their work achieved a certain notoriety because the Corps of Engineers is like a group of boys that never grew up. They have their giant pails and shovels and toys of various sorts, and they love nothing better than to dig reservoirs, and dredge canals, and build dams, and control where water goes. They did that in South Florida with an attitude, starting at the time of President Hoover, and they controlled the water in South Florida so well that they drained much of the Everglades, came close to ruining it. That’s been a subject of a lot of study and a lot of anguish over the past couple of decades. So that now today, they’re largely engaged in undoing the damage that they did long ago [laugh], reflooding selectively various parts of the south half of Florida to try to keep from utterly ruining it. At any rate, so that was Ruby’s job. It took a sort of an interesting amateur dimension because she hatched an itch to fly in the days leading up to World War II, took flying lessons from a gentleman who taught her on a very small little two-seater, single-wing plane, and she learned well. In the first instance, she was all set to be one the women pilots who ferried planes from where they were built all across America to the coasts to be put on ships and sent to war during World War II. She was a little late in getting into the enterprise, so that by the time she was credentialed to do actual plane ferrying, they were ramping down production, the war was coming to its end, and so she never actually got to deliver planes. But she was certainly capable of doing so by the end of the war, and she flew aerial reconnaissance of the lake for the Corps of Engineers as part of her job. So, she was a very interesting woman. In her later years, she had another itch, which was to open a ladies’ fashion dress shop in my hometown. And for 40 years Ruby’s was the place to go for all the women in surrounding towns if they wanted something nice to wear to a party or a ball or just out in the evening. She was quite an elegant woman, and we loved each other dearly.
Is there a book about her that I could read? I would love to (laughter).
I’m thinking of writing a kind of a low-key book of my own, which would include a chapter and possibly a couple about my mom.
Absolutely. Peter, were you—did you go to public schools growing up?
Yes, I did. Clewiston had only one elementary school and one high school. In the day I was there, it was a town of about 5,000 people. Today’s it’s a town of about 5,000 people (laughter). For a while, it shrank, and it’s regrown a little bit to about what it was when I left.
I left Clewiston after my 10th grade of high school because I hatched the desire to go to college early, and I had read much about different colleges kind of scratching that itch and decided the place I wanted to go was to the University of Chicago. I did that because I decided I wanted to be a physicist, and I have always been a person with heroes. And my all-time hero then and frankly now was Enrico Fermi, and I read everything about him that I could mop up. At that time, we had a small library in the town that was a gift from the local sugar company, the big corporate one with which my father’s company competed. I would ride my bicycle downtown and spend my afternoons in the library.
They had a pretty good collection, but the books they had were mostly dated before about 1952 because in giving them the library, the company also gave them an endowment to buy books. They spent it all then, and thereafter they had little money to buy any more books. So, it was a kind of a static collection. I had read everything they had that was on any subject related to chemistry or physics and mopped up what I could learn about Enrico Fermi. And to me, he was alive and well, and doing these wonderful things at the University of Chicago.
So, I applied there for college, and they admitted me after my 10th grade. I went there as a freshman. The first thing I did when I arrived was to go to the physics department, as I’m registering for courses, and asked, “Please, could you tell me where is Professor Fermi’s office?” They looked at me like I was a bit crazy, and said, “But, son, he died five years ago.” It was one of the biggest disappointments of my life, certainly the biggest at that time. There’ve been a few others since. That was one of the biggest.
This is a very pre-internet story.
(Laughter) Peter, what was your first entrée into physics? How did you know that this was such a fascinating topic to you, being in relative isolation in Florida?
Well, that has a few different dimensions to it. First of all, physics had a very interesting place already in Florida during my youth. It was where the space program was being born at Cape Canaveral, as it was then called. I followed that with keen interest, and it got me interested in rocketeering.
At that time, if you had a bit of money, you could buy kits of little rockets that would go up, you know, 100 feet. If you had a lot of money, you could go up 100 meters or so with your rockets. I didn’t have very much money, and so I had to be more resourceful. I was very keen on chemistry. I learned what I could of chemistry from the library when I was about 10, and I began experimenting a lot with rocket fuels.
I made some fairly good rocket fuels—nothing particularly original but, you know, the usual sorts of things with potassium permanganate, sulfur, carbon, and one thing and another. There were about three different recipes you could use. As I would make the fuels, I would test-fire them on my rockets. So, I read all the things I could find in the newspaper, etc., and NASA had rocket test stands in Alabama where they fired off solid fuel rocket engines and such. So, I made my own test stand for firing my rocket engines and measuring their thrust. And I made some pretty good engines considering the crude ways I was using.
I also was intrigued with the manned space flight ambitions of that day, and so I really wanted to have astronauts for my rockets. In South Florida there is a creature called an anole. It’s a lizard. It’s a beautiful creature. It can change colors, like a chameleon, from a brilliant green—this is one of the most gorgeous greens you can imagine—to a rusty brown, the color of a tree trunk, or anything in between, as its camouflage. Well, anoles are beautiful.
They’re also bounteous in South Florida. They’re everywhere. And they’re not particularly quick-witted or quick-reflexed. So, they will sit around on the leaves of a bush in your yard, and you can come up just kind of slowly to them, and with a fast grab, you can grab one with your hands. So I would grab anoles, and keep a little terrarium with a screen on it for them to live in. I followed closely the ways that astronauts were trained, and I decided that anoles would become my astronauts. I would train them in a centrifuge.
I had an old fan that was mounted in my bedroom because we didn’t have air conditioning as I was growing up, and that gave me a bit of a breeze at night. I would do various kinds of tinkering with it. Fortunately, it had rubber blades. It was for a child’s room. And it was very fortunate for me that I still have all of my fingers, because I would stick various things into the blades, and see how much force it took to slow them down. In all of this, you can kind of get the feeling I was tinkering as somebody with a bit of physics did.
Finally, I broke the blades off, one after another. Once they were gone, it came to me that I could use my Erector Set and fabricate a little bracket and a set of makeshift test-tube holders that would enable me to mount four Pyrex test tubes from my chemistry endeavors at the locations where the blades would be on the fan. Each test tube was just the right size to hold one anole. So, I would stage my astronaut anoles into their test tube and plug in the fan. There was no gentle start to my training sessions. And my anoles would go around and around quite fast. Some would make it through the training, and some would not. This was not a very politically correct experiment. But one does what one must, or one feels compelled to do. Some of my anoles would survive, and some of them wouldn’t. For the ones that survived, I would give them repeated trainings until they were pretty robust at it, and then they were ready for launch.
I devised a system for making an escape for the anole from his capsule on the top of my rocket. I added a little upper chamber above the rocket engine and loaded it with a bit of gunpowder. Just at the top of the rocket’s flight (the apogee), at the instant that the engine burned its last fuel it would ignite the powder charge, and the explosion would pop the upper chamber loose. I build tiny parachutes, and I would strap the parachute to the anole’s legs, so that when the capsule popped free from the rocket the anole would parachute back to Earth.
After a few casualties, I became pretty good at having these astronaut anoles pop out, float down beautifully on their little parachutes, and land. I would have a little ceremony, and I would give a moving speech, and I would release them back into nature. So, in South Florida, there are I’m sure today the descendants of a selectively bred sub-species of astronaut anoles. So, that was one of my early entrées into this hands-on science. Another was in the domains of electricity and magnetism, you have to ignite a rocket, and I watched how they do that avidly on early—on the early television that we had. And I could see that they were pressing a button, and that somehow ignited the rocket. I read up on the ignition systems, etc., and I realized that you needed to have a high-resistance element that was integrated right in with the fuel in the bottom of the solid fuel rocket. As you pass electric current through the resistor it heats up, and it had to become hot enough to ignite the fuel in the air and fire the engine.
You needed to do this from a safe distance, of course. So, I devised a way. I obtained a roll of lamp cord, just two-wired lamp cord of the conventional sort, which is covered with a rubber insulation stuff. And this by the way is very entertaining to my group because as we are talking they’re all gathered around here doing their work, and listening…they haven’t heard these stories before.
As I read up on the electric properties of different materials, I realized that steel has a much higher resistivity than the copper that’s in the wires, and I thought about how a very thin filament of steel wire would become very hot just like an incandescent bulb gets hot. Then I realized that I had what I needed ready to hand: my mother used steel wool to scrub her pots.
I absconded with one of her steel wool pads, pulled out a little ball of it, stuck the two wires of the lamp cord into the ball. I stuffed that into the bottom of my rocket engine, ran the lamp cord off 100 feet in the distance, and then there was a place in our garage where I could plug it in. Well, this drew enough current that it would blow a 5-amp or even 10-amp fuse. In those days, the fuses were of the kind that were so-called screw-in cartridge fuses. With a little experimentation I discovered something that electricians of that era knew well, which is that if you had a circuit that was blowing, and you wanted to be able to deliver whatever current you needed to deliver, there is a marvelous thing that is minted in this country in very large numbers, although they’re right now in shortage. It’s a penny!
A penny is made at least partly out of copper. It’s pretty conductive. And a penny has just the right diameter that it fits nicely into one of those screw-in sockets for the fuse holder. So, you put the penny in the fuse holder, and screw it in nice and tight. Now you have a circuit that has essentially a very large amp capacity to deliver to a load. So, I would do this modification of the electric wiring to the circuit powering the duplex outlet that I was going to plug into.
When I then plugged it in, it would deliver whatever current took to do the job. This proved to be a very effective ignition device for launching rockets, and it worked reliably for me many times until one time, which taught me another lesson about the chemistry of the rubber insulation on the wiring of lamp cord wiring. I inadvertently crossed the two copper wires where I stuffed them into the little ball of steel wool, which meant that there was a dead short basically through copper wires all the way from the one prong of the cord to the other. That meant that the amount of current that was carried was even larger than what was required to turn the ball of steel wool into a brilliant orange ignition. What it did was to ignite the rubber insulation, starting at the far end where the rocket was, and burned it all the way back to my hand.
So I plugged it in, and I saw this puff of smoke, not the ignition firing off to fire the rocket, but a puff of smoke that was mysteriously snaking along the ground toward me along the length of the lamp cord, and going sizzling and popping with flame as it was coming. I was so intrigued, so utterly rooted to the spot, that I omitted to remove my hand in time, and I had a nice pair of burns on my palm where I was holding the lamp cord as it when into the duplex outlet where the flame got right back and scorched my flesh. So sometimes you learn lessons from doing experiments.
Peter, it sounds like you had a pretty well-developed sense of what you wanted to accomplish when you got to Chicago. Did that change, or were you sort of a young man on a mission, and you more or less stuck with what you wanted to do?
I pretty much stuck with what I wanted to do. As I went through college, I never really wavered from my ambition to become an experimental physicist. I knew I was pretty sure I wanted to be an experimentalist, although that wavered a little. I stayed for graduate school at Chicago, and I toyed with going to work with Chandrasekhar on an interesting problem in gravitational radiation, which in those days was an utterly outré idea that most folks thought would never have any possibility of observation.
Joseph Weber was doing his efforts at Maryland, but most people in the world of physics viewed that as an utterly hopeless dream. The intervening decades have shown that (laughter) such ways of looking at things almost always are shortsighted. At any rate, Chandra wanted me to do the sixth-order post-Newtonian approximation as a dissertation topic if I wanted to go into astrophysics. He suggested that I talk with the gentleman who was just finishing his dissertation on the fourth order post-Newtonian. Well, I already knew enough about radiation field expansions to know that with each succeeding order that you carry such expansions, the level of difficulty and the volume of work to take it to the next order increases in an essentially exponential progression.
So, I went to see the chap who had done the fourth order. I remember it vividly—he was a gaunt Indian gentleman. I have no idea what became of him. But he heard what I came to say, and he went over without a word and pulled a volume three inches think of ring binder off of his shelf, and he handed it to me. I went through it page after page -- beautifully, elegantly crafted equation after equation after equation, continuously from cover to cover. I realized that this is the progressive development of one body of calculation, and said, “Is this the fourth order?” And he nods his head and said “You are very brave.” Well, I was not that brave. So, I decided that experiment was for me after all, and I went to work with Val Telegdi, and never regretted that.
Was there a senior thesis at Chicago?
Is there a senior thesis?
No, there was not at that time. I enjoyed many things about my college years at Chicago. In my fourth year, I pretty much took graduate courses through that year. But one of the things I enjoyed most was the experimental lab course done for the undergraduates and then for the graduate students.
And Chicago in that day took a really pretty serious approach to that in which they basically staged you some fairly challenging experiments that were doable. They were not out of scope for what a student could do in a few weeks or a month of a semester—or an order, as it was in Chicago. But they really ate you alive to make a success of it. One of them that I remember vividly really taught me a visceral connection with what the concept of a Fermi surface is all about that I would dare say not too many condensed matter physicists of today have.
A professor there in condensed matter experiments set up one of the experimental stations in the Franck Institute with a setup that made it possible for a 2-student team to measure magnetoresistance of metal samples at liquid helium temperature. They had about a dozen of these stations for all the different research groups doing their various projects. They made one of them available for senior undergraduates to use, and he staged on that everything it took to do a precision measurement of magnetoresistance in magnesium: a 3D goniometer, a background field magnet, a cryostat with a stem on it where you could mount your specimen in the magnetic field.
And so, you’re essentially doing a 3D geometry equivalent of the Hall effect, but you’re measuring the magnetoresistance in the presence of magnetic field of that specimen at low temperature. It is an utterly classic experiment. I don’t know of a university in America that enables undergrads to do that today. It is one of the most compelling experiments that you can have a young physicist do, it brings this abstruse theoretical notion that we teach people in a classroom what a Fermi surface is, and they don’t get it because they don’t realize how very tangible this reciprocal space, or k-space, is if you do things in a way that brings it alive.
That 3D goniometer measurement of magnetoresistance enabled us to map out this bizarre science-fiction monster that is the Fermi surface of magnesium so that we got to know it personally, and it’s never left me from that day to this. It didn’t turn me into a condensed matter physicist, but I know how to think like one in a very nimble way thanks to that. Likewise, there was an experiment in particle physics in which students were assigned to scan and measure high-resolution stereo films of K- mesons interacting in the liquid filling a bubble chamber. I came along in the last days of the time of bubble chamber physics. Bubble chambers had been a major instrument for high energy physics up until the late 60s, but they could not resolve large event rates and so were limited as the trend shifted to study ever more rare processes.
In a bubble chamber experiment, you injected particles produced in collisions (in our case strange particles called K-) into a pressurized chamber full of a cryogenic liquid, and you quickly release the pressure on the liquid just at the instant when the particles enter the chamber. You illuminate the chamber at that instant with flash lamps and record the trails of bubbles formed along the particle trajectories in stereo views onto 35 mm film. Then you scan the film reels for interesting events and measure the tracks to deduce the physics of each event. Two of the leading lights in that game were still on the faculty at Chicago. One of them, Riccardo Levi-Setti, and his colleague Gianni Conforto had created an experiment in which they taught us how to think about what happens when a K- meson slows and stops in a liquid. It is one of the most classic tools to bring alive for a student the strange particles, because when a K- stops in hydrogen it can do a whole variety of things. As it’s slowing down, it is doing elastic scattering. It can also do charge exchange with a proton to produce a K0 meson.
You can observe events of both of those, and learn how to recognize them by the rules of the topology and the charge—adding up the charges and all the rest, the subtle things of scanning, and have a lot of physics in them. He set us up with the geometry of the fiducial markings of the chamber so we could actually measure lifetimes. In stopping K-, you can see the production of Λ and Σ hyperons, and measure their masses and their decay modes and their branching ratios. There’s just a wealth of physics that you can do with this one medium, and the three reels of strereo film, that you put on at schools, and you go to scanning tables, and you run through and systematically measure.
So, we—I learned a huge amount in that way. I really mopped up the strange particles thanks to that experiment. No students today have that opportunity. In fact, I have what may be the last two sets of three reels of stopping K- film because I did re-create the whole experiment here at Texas A&M for about 10 years. And then I rotated off to another course, and none of my colleagues wanted to bother to continue to teach how to do that experiment.
And the basis—Peter—the basis for this concern is that there’s lots of new physics that can still be learned if this was more widely adopted today?
Absolutely, there’s no question. There—you know, there is no way, in my opinion—I am a card-carrying high-energy physicist. I’m co-discoverer of the top quark. I invented both the accelerator methods and participated in the experiment at Fermilab that measured the weak bosons. We would’ve discovered the weak bosons, except that Fermilab and the US high-energy community did not have the vision to convert the main ring at Fermilab into a hadron collider as it should have.
At any rate, bottom line is in the world today, for example, of Higgs bosons and the ensemble of Higgs that we—that are out there in the data of the two classic experiments at CERN, there is, in my opinion, very little way that you can teach that to an undergraduate, and I don’t think you can teach it to a graduate student in a meaningful way. It requires so many layers of mastering the understanding of the immensely preponderant backgrounds, Standard Model backgrounds, and how to systematically measure them and understand how they manage to feed through your various cuts that you make on data, and how to design triggers that preserve the rare events you seek but filter them from the copious backgrounds. There’s so many layers to it that it’s almost impossible to build the underpinning appreciation of the actual particles at that front-end level.
The bubble chamber thing is a complete toolkit. Indeed, you could actually put this thing on the internet with the tools of today, and turn into a videography these reels of tape and methods of using a suitably designed CAD application to do the measurement and reconstruction of the pattern of vertices, etc., and actually do the analysis or make it available to students. So, the students of today and tomorrow can have those aha moments like I did in Clewiston, Florida as a kid, where they could really come alive with these elementary particles. I know this particle. This is a Lambda particle. That is a sigma. This is how I can tell them apart.
And to a slightly higher degree already at the college level, you can equip a not exorbitantly costly cryogenic setup to do, you know, that Fermi surface measurement, although fewer and fewer universities today have any liquid helium-based experimental facilities in their lab complex. So that becomes a disabling challenge. Although now you can (with a bit of ingenuity) get down to 10 Kelvin at least with cryocoolers.
Peter, did you think about attending any other schools for graduate school, or we’re you on just such a momentum, you just stayed put and went with it?
Well, I did. I applied to Princeton and I applied to Maryland for graduate school. Princeton did not accept me. Maryland did. My motivation for applying to Maryland was actually focused on Joe Weber at that time.
Who was it at Princeton that you would’ve wanted to work with?
Well, I was interested in the things that Dicke had done. Whether I would’ve gone to work for him or not, that would’ve been, again, this experiment-theory divide. And I doubt that I had really thought that far ahead. At any rate, Chicago accepted me, and the landscape there on the faculty side (I already felt that I knew many of them) was sufficiently rich that I felt I couldn’t go wrong.
I was already attending a set of lectures that Chandra Shekhar was doing that year of my senior year of college. Chandra had the itch to see how differential geometry might play a powerful role in enabling some further exploration of general relativity writ large and gravitational radiation within it. In the end, he was partially right. And indeed many years later when talking with my colleague, Marlan Scully, here at Texas A&M (he was a student of Wigner) I found that he had devoted quite a bit of energy in his own way to differential geometry and the interface with general relativity pertinent to gravitational radiation and related problems.
That was a very stimulating year because Chandra did something that doesn’t happen often. He brought three eminent scholars of that game to Chicago at the same time to team up on this challenge. One of the visitors was Kip Thorne from Cal Tech, who just absolutely bowled me over, just a powerful, fantastic guy. And another was Robert Geroch from North Carolina—also very powerful, although a bit more erudite in his style. Chandra got a grant out of NSF that enabled him to pay their full salaries for a whole year. They ran a weekly seminar and a topical course. A whole coterie of astrophysics students tried their best to get their head around these problems at the interface of differential geometry and general relativity. Like I say, it was largely fruitless at that time, but it was immensely stimulating to me.
Ironically, one of my postdocs, Bill Kells, went into that game right after working with me as a postdoc at Fermilab. He came to work with me when I was building the electron cooling ring for proton and antiproton colliding beams, but he left that postdoc to take a position with the LIGO group at Caltech who were then just beginning to build the immense gravitational wave observatory. Bill devoted his entire career to LIGO, and retired from Caltech and from LIGO about six months before the first discovery was announced of the black hole mergers. [laugh] So it’s literally a case of going into the early phase of a huge, visionary, experimental enterprise, spending your entire working life from your second postdoc all the way through to your retirement building that thing, failing with it on its first round, rebuilding it, failing on its second round, upgrading its sensitivity by two orders of magnitude, and then sharing the spectacular discovery just as you retire! (laughter)
Bill’s name is on the discovery papers, but he retired just as they finally announced the first of the now many, many black hole mergers that they discovered. It’s such an exciting arena in our field.
Peter, on the social side of things, your graduate years coincided with a quite tumultuous time, nationally and in Chicago specifically. What was your relation to all of the movements that were going on on campus at the time? Was your sense to sort of try to stay away from that and keep your head in the lab, or were you involved in some of those movements?
I was on the picket lines in Chicago. I was vehemently antiwar. The Vietnam War was one of our utterly wrong wars that we as a nation have had the lack of wisdom to fight. I was determined that I personally, Peter McIntyre, was not going to go to Vietnam under any conditions. I had determined that if necessary, I would leave the country. I would not go to jail if I could help it, but I was not going to go to Vietnam and either kill people or be killed for no just cause. I graduated from college in ’67, and I was a graduate student beginning then in ’68. That was the last year for graduate school deferments from the Selective Service. That enabled me to get through my first year of graduate school, and I got my master’s at the end of that year, and I also passed the qualifier exam, so I was then a PhD candidate. But as that year ended, also ended the graduate student deferments.
That brought this issue to a hub for me personally. I studied the legal paths by which I could qualify for any form of deferment. I was a conscientious objector, but not in a fashion that was defensible under the rules of Selective Service, so that was not an avenue.
Meaning there was not a religious basis to your conscientious objection?
I was not going to lie and say that God told me not to go to war. Ethics was not an allowable basis for conscientious objector. It’s one of the sad comments about our country. So, as I sought any avenue that there might be, I found that there was a curious loophole in the medical criteria that are applied when you are drafted and sent for your induction physical. They have a little chart of weight vs. height. For each height, there’s a maximum and minimum weight that they will take as draftable. If you are less massive than the minimum or more massive than the maximum for your height, they will not take you into the Army. I was a pretty lean and gaunt kind of guy in my youth. I’m still pretty lean and trim.
And so, I looked at the chart and saw with interest that the threshold for minimum weight for my height of six-three was 138 pounds (if memory serves correctly). Well, I at that time weighed about 155. I then researched how the process works from when you receive an induction physical from your local draft board to when you show up for a physical in your location where you are. My draft board was in Clewiston, Florida. I was at the University of Chicago, and they didn’t require you to go home for an induction physical. That would not be a reasonable thing to do. So, they send you a notice to appear to the induction that serves Clewiston, Florida. You then have to respond within a certain maximum window of time to request a change of venue to the induction center nearest where you are.
So, I worked out a plan, and realized that if I took the maximum allowable time to request the change of venue, that would engender a process that took several weeks to actually make happen. I planned to fast beginning the day I received the notice for physical and strive to reduce my weight sufficiently that I would be below the acceptable threshold when the time came for me to report for my physical. The first episode of this came, and I managed to fast my way down to 130 pounds, reasoning that their scales might be a little off, so I needed to leave a significant margin. They put me on the scales, and they gave me my I-Y status.
But a I-Y is not what you hope for. An IV-F is what you hope for. But I nevertheless felt pretty good about that. Alas, six months later, I got another notice for another physical. I repeated the same sequence of events, and it had the same outcome. So, I thought, well, surely—but, again, they gave me a I-Y.
I began to think how long is this going to go on? Well, they were thinking the same way. So, the third time, they sent me a notice to report to the station in Chicago where they sent me on the previous times on the second bounce. So, this time I had only two weeks before I had to report.
I went on to an all-out fast. I worked out what you have to eat if you’re going to manage to survive physically and not die, but also you’re going to plunge your weight in the fastest attainable way. The answer for any who need to do it is sea scallops and celery. If you eat only sea scallops and celery, you will get the protein you need, you will get near-zero carbohydrates, and your weight loss will only be limited by your water content.
It was working, but not fast enough. For the last week before the physical I had to diminish my water intake because that’s the only way you can reduce your weight very fast. On the day of the physical my wife Becky drove me to downtown Chicago, and I staggered from the car into the induction center. I staggered through the physical. When I came to the end, my weight was 133.
The final station was a doctor does the summative evaluation. He has all the data - they took a blood test and urine test and X-rays. He looked at the data and then at me.
He said, “Son, you’re going to get your IV-F after this. But let me tell you, don’t ever do this to your body again. You are about 12 hours from death, from going into a coma and dieing.”
“So you really don’t ever do this again.” And I said, “Yes, sir.” (laughter)
And I take it you were not working with any kind of medical oversight when you were doing this to yourself?
Oh, no. Doctors faced jail if they were willing to counsel people in doing what I did.
Yeah. Peter, looking back, what do you think accounts for—I mean, a lot of people say they were antiwar and they didn’t want to go to Vietnam obviously. But your commitment to this was clearly unique. What do you think accounts for it?
It wasn’t unique. There were many people who did the same character of thing. Some of them did it by leaving the country; others by managing to get a CO; others with weak knees; others by breathing iodine vapor, which is also not good for you (laughter) but makes you fail a lung X-ray, which is another part of the physical.
I was not alone in that. What I shared with them was an iron determination I was not going to go out to Vietnam. I was not going to kill other people or have them kill me for a wrong war.
There was no moral justification for that war—then, now, ever.
So, the emphasis here is that you’re not necessarily a pacifist. If you rewind 20 years, you may have been willing to fight for World War II. Your specific objection was with the Vietnam War?
Yes, that’s correct. World War II—all wars are a very mixed bag in the best of ways of characterizing them. But some of them have justifications, and others have none. The Vietnam War had no justification at all. We went into it on the basis of lies, the Gulf of Tonkin. We were dragged along through it by a continuous sequence of lies.
We did atrocities that are beyond imagining to the human beings on the ground. And there’s just nothing good you can say about it. It killed 50,000 of our own people. It killed a million or so of the Vietnamese, all to no good purpose.
Did you talk about your decisions with your parents? Was there a generational divide, or were you of the same mind on this topic?
There was a total divide. My father was a member of the John Birch Society. I think in his heart, he knew what I was doing. I did not make a secret of my views about the war—we would have candid, frank discussions about that, but they had to end up with us agreeing to disagree. I did not rub in his face what I in the end had to do to stay out of Vietnam.
How did you recover, and how did you get back to a sense of normalcy for your graduate work?
You mean after fasting?
I ate (laughter). I had many very good meals (laughter). And I never did that to my body again, as the doctor suggested.
How did you go about developing your dissertation topic?
Well, after just making my decision I described with Chandra Shekhar, that switched me into a kind of a resolve that I wanted to become an experimentalist. I had—I really had a love for particle physics, and two faculty who were most active in particle physics at Chicago at that time were Val Telegdi and Herb Anderson. So, I went to talk to both of them. Anderson was doing mega-scale counter-based experiments at Argonne National Laboratory, and preparing an experiment for the brand new Fermilab that was just being built. I talked with his group, and understood what they were doing as an experiment. I did not find it inspiring in its physics motivations. It seemed to be mainly an exercise in fancy electronics to handle what then were large quantities of data.
Telegdi at that time had already done one experiment in muonium, and was gearing up to do another. And so that experiment had the prospects of being the basis for my dissertation research if I wanted to do it. The more I learned about it, the more fascinating it became for me. Muonium is this marvelous atom of a positive muon and a negative electron that forms very naturally if you simply stop μ+?in an inert gas.
As it stops in the gas, the muon will latch onto an electron, and bind it into a very small radius atom. That atom is 200 times smaller than the gas atoms (the ratio of mass of the muon to the proton). So, the muonium atom is an extremely inert, isolated, little atomic system that has the remarkable property that it has no strongly interacting pieces in it. It’s just two leptons that are bound together in a bound state. Correspondingly, if you study its hyperfine structure (the atomic levels of the atom), if you measure the hyperfine interval between the two spin orientations of of its ground state, you’re making a measurement that is utterly fundamental in QED, quantum electrodynamics.
This was in 1971, and in that era measuring QED with ever greater precision was a very hot and lively topic because that’s where you could see the virtual diagrams of gauge fields beyond electromagnetism to the weak sector. The electroweak bosons W and Z (then only conjectured) gives a dominant term that you can pull out as a virtual diagram from those studies. So what you want—what was then the lively challenge was to make ever more precise experiments of this beautiful little, isolated little atomic atom through extreme precision.
So, my dissertation experiment used a method called Ramsey resonance in zero field. That’s a marvelous little piece of experiment, very characteristic of Telegdi’s style to devise this beautiful way of doing things. You measure the hyperfine integral in the absence of any background magnetic field—not by splitting the two hyperfine levels using a Zeeman. In the absence of the splitting, you apply a pulse of RF field, then turn it off and let the two hyperfine states evolve as quantum mechanical eigenstates, and then you apply a second analyzing pulse of RF field, and you measure the hyperfine interval thorugh the phase evolution of system after the second pulse.
Ramsey’s elegant method has been used in lots of classic experiments - in atomic physics. quantum optics, MR imaging, and NMR spectroscopy. It was such a beautiful experiment.
An irony followed in what was intended to be a follow-on experiment, in which the same split-field technique would be used in the presence of a magnetic field, at a particular magic field strength that was predicted to kill the first order terms that would otherwise create systematic effects. In theory that seemed to work very nicely. Alas, we found out the hard way that it leaves you wide open to terrible systematics arising from the details of the pulse structure of the polarizing and analyzing pulses, which produce artifact phase shifts that you can’t really control or even measure. Those make offsets that make your precision measurement bounce all over the place in succeeding runs. That succession of success and failure was a valuable lesson to me as a young physicist.
I learned an immense amount working under Telegdi, with his meticulous style of devising precision experiments that could test the fundamental guage symmetries. That style was diametrically opposite to the style of the next scientist under whom I worked.
After my experiments with Telegid I went to CERN as a Visiting Scientist and joined the team of Carlo Rubbia. Rubbia is the extreme opposite in all possible ways from Telegdi. Telegdi was this wizard of a chap who loved precision experiments, thoughtfully controlling by design every nuance of the things that could screw up his precision measurements and wrestling the thing down to just a beautiful art. Telegdi was just that embodiment. Rubbia, on the other hand, is a swashbuckling son character who strives to devise ways to get results quickly and find evidence of new physics before anybody else. And he succeeded spectacularly on the one occasion of discovering the electroweak bosons W and Z. He fell flat on his face multiple times before and after that, as with the false-discovery of the top quark that he championed at CERN, and the oscillating weak neutral currents before that era.
I’m familiar, yeah.
At any rate, I never regretted one moment of my years with Rubbia, and I learned elements of style and ways of thinking from Carlo, but I retained the appreciation of precise measurements and method that I learned from Telegdi. Those two themes have made me what I am as a physicist.
I can’t help but point out that physics needs both of those kinds of personalities to—
They really do. And there are woefully few of either kind today. There are probably very few swashbucklers left in high energy physics. There are a lot of organization men and women trying to figure out how they’re going to keep their grants up and struggling to position themselves in large collaborations. But those are not necessarily compatible skills with some of the kinds of creativity from which discoveries arise.
Now, Peter, when you defended and were thinking about postdocs, was it CERN or bust? Was that really where you wanted to be, or were you looking at, you know, Brookhaven, SLAC, Fermilab? Were you more broadly interested just to be in a major laboratory environment?
Well, that one’s fairly simple to answer. I stayed with Val as a postdoc for the better part of a year, and that was when we did that failed experiment with split-field resonance at magic field. As that year ended, Val called me in and said, “You need to look for your next postdoc. And I have a suggestion for you.” He said, “Right now at CERN, they are building the next-generation muon g-2 experiment. An old friend of mine, Emilio Picasso, is the head of that enterprise. And I believe that the best thing you could do would be to apply to CERN for a Visiting Scientist position, and if you get it, then I believe you should join Emilio’s group. It’s an absolutely classic experiment.” I mean, you know from the history thereafter how classic it is.
They were building at that time what was the second generation of what now is a total of four generations of muon g-2 experiments. It’s another pure lepton virtual diagram experiment that can probe with extreme sensitivity the virtual diagrams from Higgs and from beyond. It has many potential systematic backgrounds, and so experimental design is utterly key to its success. Today the fifth generation muon g-2 experiment is being built at Fermilab, and I wish them well. Indeed, one of my former students is working in that team at Fermilab.
At any rate, I applied to CERN and I didn’t apply anywhere else for a postdoc. I applied to CERN as a Visiting Scientist, and they accepted me. When I arrived, they explained that I was free to work with any group at CERN, and they urged me to spend my initial days to identify three or four groups around the laboratory who are doing experiments that I found interesting and spend some time with each to decide which I wanted to join.
Telegdi had already explained this to me - that every group would want me because as a Visiting Scientist position CERN pays my salary for that precious year. For me, it turned into a year and a half, but it’s a very finite-duration postdoc, and there’s no question of a future staff position for an American at CERN. Well, they hired one American: Steinberger. But that’s—he’s a little exceptional. He has a Nobel. So I took the advice. I talked first with the muon g-2 group. Picasso was very warm and welcoming, he’s a wonderful man, and he lined me up with Frank Krienen, who was the wizard of that experiment, tackling many of the most challenging aspects of experimental design that made it a complete success. They were very welcoming to me, and we discussed the roles I could play in the doing of their experiment. I’m sure it would’ve been a wonderful year for me if I had done that.
Then I went to talk with Rubbia and his group. Rubbia at that time was running an experiment on ISR, the Intersecting Storage Rings, which at that time was the only colliding beam machine in the world at that time: 30 GeV per beam. Rubbia’s experiment was a marvelous spectrometer in which he was doing deep inelastic scattering, with a single arm spectrometer with particle identification (Cerenkov counters), calorimeters for identifying electrons, multilayer shields to identify muons. The inspiration of this experiment came from a succession of results from several other experiments at ISR and at fixed-target geometries that showed an excess of positrons produced with large transverse momentum. Just the proton-proton collision makes some positrons (about one in 10000 collisions) and you can explain the origin of those events from Drell-Yan production of e+e- pairs. There are also mechanisms that you can cook up and produce a positron for inverse diagrams with strange particle decays and one thing and another.
But all of those are calculable, and they give you an expected level of positrons : e/π = 10-4.
But Rubbia’s spectrometer was detecting ten times that many positrion! It was a real smoking gun for new physics, and it was a complete mystery.
Rubbia had an idea about where they were coming from because he was a professor at Harvard at that time. And he went back every week to the US, both to lead the Harvard role in the deep inelastic neutrino experiment at Fermilab, and also to teach at Harvard.
Harvard at that time was the place to be in the entire universe for understanding the next generation of particle physics because that was the place where Weinberg and Glashow and Coleman were basically inventing particle theory. Those guys, there’s just no exaggerating the profundity of their intellects. The positrons we were seeing were in retrospect produced by beta decays of from charmed particles. The D+ can be produced in strong interaction processes in proton-proton colliding beams, then the D+ decays weakly into positrons through two levels of a cascade sequence. The high-momentum positrons we were seeing came from the gamma boost they got from the decay of the heavy D meson.
But our experiment was happening before charm was conceived of in a robust way, and certainly before it was discovered. Later in that year the Ψ vector meson was in fact discovered more or less simultaneously by Ting and by Richter. And about that same time, we got our data sets really tuned up, and everything in our experiment understood, and produced beautiful excess positron results that were a very clean smoking gun that aligned elegantly with the charm hypothesis that now became the electroweak theory and the GIM mechanism that were being invented by the theorists at Harvard.
So, I caught the bug visiting with the people in Rubbia’s group, and most particularly visiting with him, and I was an enthusiastic member of their team for that year and a half that I spent at CERN. I came back from CERN to be an Assistant Professor at Harvard, which at Harvard mean I came back to be the assistant to Professor Rubbia. And that was when I came up with my ideas for proton-antiproton colliding beams. But those ideas were born at CERN.
In the trajectory of my career, that time at CERN was immensely important to me because it was my first blush with learning how an accelerator works, how a collider works, how to think about beam cooling. Beam cooling hit its spectacular successes while I was there, both with the stochastic cooling of van der Meer and colleagues at the ISR, and with the spectacular success of electron cooling in Novosibirsk which happened the same year. I managed to get a plane ticket to Russia, and I spend a week with the group at Novosibirsk and learned how electron cooling worked. I spent a sideline activity during my last six months at CERN in a close collaboration with a Paolo Strolin, who become a close friend and colleague.
Paolo was an engineer by training, and worked in the group of van der Meer on the ISR. He had been part of the team that did stochastic cooling, etc. He had become intrigued also with experimental particle physics and hatched the career goal to become an experimental particle physicist, after his training in engineering and accelerators. Paolo persuaded Rubbia to take him on for a year in his team on the ISR experiment.
Paolo and I and three or four other young postdocs at CERN were keenly aware that buried in our respective trenches, we weren’t really able to get a bigger view of the exciting things going on in the rest of the world. So, we formed an impromptu journal club that met once a week, with as much wine as we could afford, and we would each take turns either giving a talk, or lassoing a visitor to CERN to give us a talk on something interesting. This was a totally self-organized enterprise of these postdocs, which is the most powerful sort of thing that can go on.
It was in the course of this that Paolo made me aware of the exciting results in Novosibirsk, and so he taught me how to think about electron cooling, and he and two or three of his colleagues in the ISR group taught me how to think about stochastic cooling.
And Paolo and I began brainstorming how one might use this new beam cooling to make colliding beams, and in particular make colliding beams of protons with antiprotons. Could we manage to cool a beam of antiprotons, and store them in a storage ring, and then inject them to one ring of the ISR to make proton-antiproton colliding beams in that same facility?
There’s something to be said for that, but only a limited amount. The thing to be said is that that then gives you the annihilation channel of valence quarks colliding on valence antiquarks, which extends the mass reach with a given luminosity you have to discover a new particle or field of nature. But it had the disadvantage of course of the limitation that the top beam energy possible with the ISR was 30 GeV.
Well, clever as you may be, you cannot use 30 GeV on 30 GeV to make, you know, an electroweak boson (laughter). Already at that time, purely from what was beginning to emerge from the Harvard wizards of electroweak theory, we knew that the mass of these gauge bosons, if they did exist, would be, you know, 80 and 90 GeV. Nevertheless, we worked through systematically all of the accelerator design that one must have for a more or less credible scheme for cooling and accumulation of antiprotons in that context.
This is what I’m here for. This is it.
Okay. So, the gentle irony of this for me personally is it became obvious to us that there was actually a beautiful, almost made-to-order storage ring that had just the right parameters to be a cooling ring where we could do these experiments, and actually make antiprotons, and store them and cool them. It was the muon g-2 ring. But that moment was when the muon g-2 ring was beginning to work, was beginning to make its first measurements of muon g-2!. We had to realize somewhat bitterly that the last thing in the world that anyone at CERN would welcome was a couple of renegade postdocs coming along with a clever idea for how they could displace the muon g-2 team from their own machine so that we could do cooling experiments. The final irony of course is that is exactly where they did do the antiproton cooling experiments just 2 years later, and the muon g-2 ring became ICE, which is still cooling antiprotons today!
So, a few months later I then came to Harvard at the end of that CERN postdoc. And as Rubbia’s assistant professor, my job was to run his role in the neutrino inelastic scattering experiment at Fermilab where we were observing another consequence of charm, namely dimuon and trimuon final states in neutrino scattering. That experiment was a collaboration of Rubbia and Mann from Penn, and Cline from Wisconsin. And that’s where I got to know Dave Cline, and we became friends through the rest of his life.
There came a day, and I can even tell you the day—well, I can tell you within a week of the day. In late 1975 I was freshly back from CERN and taking on running Harvard’s role in the neutrino experiment. At that time Fermilab was beginning to build the superconducting magnets for its Tevatron – which was to be an upgrade for their accelerator from 400 GeV to 1 TeV. Wilson had been barraged for some months by letters and visits from the literati of experimental particle physics, banging on his desk that Fermilab should think of ways to turn its new Tevatron into a colliding beam machine because it might have the reach to discover the weak bosons.
There were three ideas to these great physicists were pushing to Bob Wilson, the Director of Fermilab. They all involved ways to make collisions between two beams of protons, each beam circulating in a separate accelerator. One idea came from Rubbia and Klein, suggesting that a proton beam in the Tevatron should be made to collide with another proton beam circulating in the 400 GeV Main Ring at an intersect where the two rings were made to cross. There were several immense practical challenges that were almost certainly insuperable (asymmetric beam energy compounded with the woefully inadequate 50 m straight sections in the Main Ring tunnel), but Cline and Rubbia were both swashbucklers, and swept the details aside.
Another idea came from Leon Lederman. Lederman teamed up with a physicist named Jimmy Walker, and they proposed proposal to collide a proton beam from the Tevatron with a proton beam in a small circular accelerator of perhaps 30 GeV energy.
Their idea overcame some of the limitations of the Rubbia-Klein scheme, but it had woefully inadequate energy to have good reach for the discovery of the W and Z, and it was a very awkward geometry to make a tight low-beta squeeze with high luminosity. And in all of those, you were colliding protons on protons.
A third idea came from Burt Richter, co-discoverer of charm. His ideas again proposed asymmetric proton-proton collisions between two beams and was unworkable.
None of these illustrious physicists had the notion of colliding protons on antiprotons, because few in the United States in those days of late 1995 had heard of stochastic cooling at CERN. Accelerator physicists at Fermilab viewed it as probably a piece of flummery because it appears to violate Liouville’s theorem. Most accelerator physicists of that day took Liouville’s theorem as the word of God that you cannot violate - conservation of invariant phase space.
So all of the leading physicists of our field in the US were pushing Wilson to find a way to make collisions of protons on protons to make weak bosons, but all of them would’ve failed. And the theorists were realizing that what you can do on the back of an envelope that those schemes would not likely succeed in finding the W and Z. Wilson responded to their urgings by announcing that there would be a workshop in January 1976 where all ideas would be presented before the whole Fermilab family and critiqued to see if there were any that could work. He invited the user community and the lab’s accelerator physicists for the occasion.
I dug out our designs for beam cooling, and antiproton accumulation, and realized that we could make it all work beautifully to make proton-antiproton collisions in a single ring – the Main Ring or the Tevatron at Fermilab, or the SpS at CERN. That approach would have none of the limitations of the two-ring schemes, and they had plenty of collision energy to find the W and Z.
So, I heard about this meeting, and I decided to stick my neck out. I sent a memo to Alvin Tollestrup, whom I’d never met, explained briefly my ideas for beam cooling and pp colliding beams, and requested floor time in the meeting to present my ideas. I half-expected that I would not be invited to speak, because I was a green-horn and had no credentials in accelerator physics at all. But, no, he gave me floor time.
So, January 24th, 1976 was an important day for me. I stood up in front of a pretty full auditorium at Fermilab, and gave a presentation of how beam cooling made it possible to gather a significant phase space into the aperture of a cooling ring, and how you could then cool that phase space, and then accumulate repeated production cycles, and then put them into the Main Ring and make colliding beams, and discover the weak bosons.
The elegance of pp is compelling. The proton and the antiproton have exactly the same mass and opposite electric charge, so if beams of protons and antiprotons are injected into an accelerator with the same momentum, traveling in exactly opposite directions, they would travel around the same circular orbit through the racetrack of dipole and quadrupole magnets! It gets even better: as the beams pass through radio-frequency (RF) resonant cavities that accelerate the particles to higher energy, the protons and the antiprotons are accelerated to higher energy at the same rate. So, you can inject an accumulated bunch of antiprotons going clockwise in the Main Ring at Fermilab, with 8 GeV of kinetic energy, then inject a bunch of protons going counterclockwise, and they will nicely orbit the same circle! Now you can simulataneously ramp the magnetic field and apply RF acceleration, and both of the counter-circulating bunches will gain energy while continuing to travel the same orbit! You don’t need to spend a billions of $ to build two new magnet rings for two beams of protons to travel separately!
Tollestrup gave me 20 minutes to talk at the meeting. Throughout my talk I saw people turning to each other and laughing and making their side remarks – many thought it a silly joke. But they let me finish.
And then at the end, there was polite applause, and then the barrage of questions began. “Professor McIntyre, have you ever heard of Liouville’s theorem?” I said, “Yes.” “Well, what you just described violates Liouville’s theorem.” I said, “No, you’re incorrect: you’re not dealing with the phase space of a single entity. The cooling mechanisms make it possible to divide the phase space into separate pieces, re-arrange the pieces closer together without losing particles, and then reassemble the pieces into a smaller phase space volume.
“But you can’t do that!” I said, “You’re misapplying Liouville’s theorem. Yes, you can divide and re-assemble without violating Liousville.” I had to answer that same answer about 10 times, and with each answer there was laughter, but with each round there was less laughter. At the end of the talk, it ended on a kind of a silence.
That night, Carlo Rubbia and I had to fly back to Harvard. As we sat together on the flight, Carlo turned to me and said, “Peter, today, you were right, and I was wrong today.”
“We’re going to make this happen, and we’re going to discover the weak bosons.” We then spent the rest of the flight talking through a succession of the physics details of that whole thing, both on the particle physics side and on the accelerator physics side and developed a framework for the various directions we would pursue thereafter. And of course, Rubbia is one of the past masters at giving structure to a plan once you work out what you want to do.
The outcome of that at CERN was to bring Rubbia personally into the picture of this idea of mine. He could see the whole thing from that moment as a path to the Nobel. Just as he spanned the physics programs at Fermilab and CERN and traveled between them constantly, Carlo began doing his best to infect the people at CERN with the vision of pp in their SPS. This came at a perfect time for CERN because CERN was writhing with envy after discoveries of charm at Brookhaven and SLAC (awarded the Nobel that year) and how Europe had so totally missed the boat on that.
I mean, charm could’ve been discovered at the ISR by Lederman, for one, by DiLella for another. Their two different experiments on two of the intersects of ISR recorded dilepton final states in proton-proton colliding beams. In both cases the teams regarded the resonant bumps as unwelcome fluctuations because they didn’t fit their models of Drell-Yan continuum that was at that time the vogue way to study the electromagnetic form factor of the proton. I mean, it makes you just sort of swoon in vexation that two different groups of phsyicists could be so stupid.
So, the Europeans were writhing in how they had missed the boat on this. And Rubbia showed them how they could use their SPS plus their discovery of one of the two forms of beam cooling to discover the weak bosons. And from that day on, he had a virtual carte blanche to develop this at CERN.
Fermilab meanwhile had precisely the same possibility – its Main Ring operated at 400 GeV energy, much higher than the 270 GeV of CERN’s SPS accelerator. It was adequate for making a colliding beam machine. But Fermilab’s culture was downright hostile to ceasing that opportunity. And that’s how sometimes history is written.
To many among the leadership in US high energy physics, including Lederman, it seemed a sacrilege to propose to dedicate their whole lab’s vitality to transforming the Main Ring into a collider. It would delay the commissioning of the Tevatron, and of course ultimately the Tevatron would provide even higher collision energy. Also, Lederman had an experiment running at Fermilab, using the beam from the the Main Ring to deliver protons for studying deep inelastic scattering of protons on a metal target to produce Drell-Yan pairs of muons. Years later that experiment migrated to the Tevatron, and ultimately discovered the b quark, which earned Lederman the Nobel.
So, Lederman saw this as an unwelcome diversion from the path of extending the reach of his dimuon experiment just to make these colliding beams that, in his view, likely wouldn’t work anyway. So that was the impasse I struggled with at Fermilab. I focused my energies on striving to persuade the people at Fermilab to give priority to transform thei Main Ring into a pp collisider. I failed.
Wilson gave me a group and bankrolled the building of a cooling ring where we demonstrated and studied both electron cooling and stochastic cooling. It gave us the wherewithal to design what ultimately became the antiproton source that was built for the doing pp at the Tevatron. That whole ensemble then evolved with time to produce just an amazingly successful method of making proton-antiproton colliding beams. The Tevatron was a spectacular collider. Few physicists realize that the Tevatron collider program produced a luminosity of proton-antiproton colliding beams at 2 TeV that fully equaled the best luminosity that LHC managed during its first long run of proton-proton collisions in LHC a decade later. The US did another dastardly deed when they ended the Tevatron program, and in effect ended hadron colliders in the US. Anyway, that kind of takes you through my era of postdoc and assistant professor.
When you accepted the job at Harvard, what were your feelings on the prospects of tenure? Did you feel like—? This was like you just thought this was going to be an impossible thing, but it’s too good of an opportunity to pass up?
Tenure at Harvard for an assistant professor at Harvard, at least in those days, was essentially a joke.
And you knew this going in?
Oh yes, absolutely. And ironically, I was told by several of my Harvard faculty colleagues (but not by Carlo) that when I handed them my resignation to take the job I have now at Texas A&M, they were shocked because they said, “Well, you know, we were going to consider you for promotion in just another year or two.” And I said, “Well, you might’ve considered me, but it would’ve been a halfhearted consideration because I’ve seen your track record.” “You look only outside your own gates for where you’re going to find the next person that you anoint with a tenured position. You don’t look to promote from within, so why should I have believed in that?” On this—on that particular round of—you asked about the previous rounds of my career.
I applied for a follow-on position at Caltech and at Berkeley and at Harvard. Berkeley offered me a job, and Harvard offered me a job. And so, I talked to several of my colleagues at CERN in deciding which of those offers I should take most seriously, they both had pros and cons.
Berkeley does promote from within not infrequently, so that was definitely a pro. Harvard essentially never does, and I already understood that from the instance at CERN. On the other hand, charm had just been discovered, and that truly launched a revolution in our understanding of nature at the subatomic scale. I realized that virtually the entire coterie of particle theorists who were redefining what we understood to be the Standard Model were all at Harvard. It was an amazing place at that time.
So, to me, that decision was a no-brainer: go to Harvard, team with Carlo in his neutrino experiment, and learn the new wave of physics with Shelly Glashow and Steve Weinberg and Sid Coleman. I’ve ha d the good fortune to have made some very good choices: in some cases, by a little bit of flip to the coin, in other cases by forethought, that enabled me to grow and do interesting things.
So, in terms of the chronology, were you at Fermilab as a sort of a—as part of a gap between Harvard and A&M, or that was part of—on either side?
I came to Harvard as Rubbia’s ‘assistant to the professor’. My role for him was to be the chief cook and bottlewasher for the deep inelastic scattering experiment, neutrino scattering experiment at Fermilab, experiments E1A and E310. Actually, it was E310 by the time I got there. It was the dimuon embodiment of the deep inelastic multi-lepton experiment.
I would fly weekly between Harvard and Fermilab, At Harvard I immersed in learning how to think in gauge theory colleagues. And on the Fermilab end, I rose to the challenge of how to transform their accelerators into proton-antiproton collider. And I managed to get Wilson sufficiently energized so that he gave me a group at Fermilab as a group leader in parallel with my appointment at Harvard, and gave me the rope to hang myself (laughter)- He backed me to build and run this experimental storage ring so we could study and perfect the beam cooling methods that had been discovered in Russia and CERN. I learned accelerator physics more thoroughly at the knee of Fred Mills, who was a long-time accelerator builder at Fermilab, then approaching retirement age, who had been a veteran of the MURA days that pre-dated Fermilab. MURA was a kind of ferment at University of Wisconsin that led to the design of Fermilab, its Main Ring and the whole accelerator complex at Fermilab. So, step-wise in each of those venues, and largely in parallel, I learned these different parts of the trade, and how to use them.
Did you—were you comfortable at Texas A&M as soon as you got here?
And where was the department at that more- was—were you—was your hire part of a broader growth mode for the department?
Yes, it was. The chair of the Physics Department at that time was Robert Tribble, who is an eminent nuclear experimentalist. He’s now Associate Director of Brookhaven. Bob was at that time a pretty young guy. He’s just a couple of years older than I. He had become Department Head in a hiatus in this university when our department was kind of at a low ebb.
The previous Head had none of the kind of moxie tools that it takes to build a faculty or even to retain its strength. The College realized that the department had the numbers-game capacity to add quite a few faculty lines, and they wanted a new Head who could meaningfully guide that growth.
So, the Dean put the challenge to the Physics faculty. “You go find who you want as an internal candidate.” Then ensued the usual sort of internecine battle, with a few desiring to be Head, each hoping to steer that growth to his sub-field. And then there was Tribble.
Tribble didn’t throw his hat into the ring because he’d only been there a modest number of years, and he was not looking to build himself as a bureaucrat. He was looking to do nuclear experiments, and he’s damn good at it. The others kind of destroyed one another in the feud. But when the key faculty meeting arrived, th factional groups within the department were at a stalemate. As it was told to me, Tribble raised his hand, and said, “Well, I’ll do it if nobody else wants it.” And they all turned to him and said, “Well, you’ve got a damn good reputation in what you do, so give it a whirl.” The Dean bought on and handed him a carte blanche with half a dozen faculty positions to fill. Tribble decided to devote two positions to particle experiment because there was then no particle experiment at Texas A&M. Well, it’s kind of tricky to recruit people who are potentially going to be good at that game into a vacuum. People want to go where there’s something they can build on, right?
Tribble first called up Bob Webb, a chum from Princeton, where they had both been graduate students, and pitched this to him. Bob was then at UCLA, and was a co-PI on a collider experiment on another of the intersects at ISR. So Bob and I had known one another during our year at CERN.
Bob was interested, and asked Tribble to approach me to make it a team. I get a call one day from Tribble. He asked me if I’d ever thought about looking for a new home, and I said, “Well, I’m an assistant professor at Harvard, so I’m always looking for a new home.” (Laughter) And the—
And the idea was that you would come on tenured, right?
Yes, but rather obviously, there would have to be a very short trial period, but with virtual certainty of tenure in the offing. So, I was pretty offhand with him. I’d never heard of Texas A&M so the first thing I said is, “Where is Texas A&M?” (Laughter) “What do your faculty do there?” And the answers were not particularly encouraging to me. But before making a decision, I decided I called my mentor Telegdi. I told him I was being recruited for a position at Texas A&M, and there was a pause on the other end of the phone.
And Telegdi said, “Well,” he said, “Peter, I don’t know very much about Texas A&M. But I do know one person there whom I think very highly of. His name is Ed Fry, and he is a first-rate atomic experimentalist. The phrase quantum optics had not then been coined at that time, but it describes Ed does. He is a master at doing subtle things with controlling phases of atoms and beams of light. And he is undertaking what would be the ultimate experiment in Bell’s inequality, to close the last of the loopholes in Bell’s inequality, and either, you know, shit or get off the pot. Either it makes or it breaks that dimension of understanding quantum mechanics. It was a very important experiment. Many people have done variations of experiments on aiming to test Bell’s inequality. Every one of them has left loopholes that can give ambiguity to interpretation of the results. So, none of them has really settled this fundamental problem. I should then hasten to tell you that there remain, at least in the opinion of quite a few of us, some remnant loopholes in Bell’s inequality to this very day.
So Telegdi responded to me “Ed Fry has concocted a conceptual design for an experiment that I believe could close the loopholes.” Well, that coming from Telegdi was high praise indeed, because Telegdi was the kind of guy who really focuses on that kind of nuanced experiment to eliminate systematic effects to the last possible degree. Indeed, he had been beating his head on his own experiment of that character for the past three years since I had last spoken with him.
Telegdi said, “Fry has designed, in my opinion, the very best experiment anyone’s come up with yet, and he’s in the process of building it, and I have high hopes that he’ll make it work.” Well, the post note to that is Fry has still not made his experiment work today! He has put it on the shelf over and over again in consideration of one or another thing that he’s undertaken instead because it wasn’t quite so difficult. He’s become the past master of several more mundane things but things that some people consider important. So, he’s never actually buckled down to do that ultimate experiment in the proper way, something that I rag him about on a regular basis.
At any rate, Telegdi’s answer to me is if Texas A&M is where Ed Fry is, it can’t be all bad (laughter). So, I flew to Texas, and made the visit. Webb and I talked through what it would take to build a group at Texas A&M create and take an achoring role in a proton-antiproton collider experiment for Fermilab, which was then beginning to organize itself to design and build a collider detector for what they had by that point begun to gird their loins for of building an ultimate pp collider once the Tevatron had done its first runs as a fixed target accelerator.
And, Peter, at this time when you were thinking about coming down, even the faintest whispers about a future SSC, this is way before that, right?
Totally before. There were no faint whispers about SSC until after the weak bosons were discovered.
Rubbia found the weak bosons at CERN in 1983, just after the Tevatron had been commissioned as an accelerator. By about 1980, the Fermilab had completed the Tevatron and commissioned its runs as a fixed-target collider, and was making its serious design of an antiproton source following our running and learning from the cooling rings.
It was in that window of that time, as Fermilab was getting into the serious game of building a collider detector in parallel with building the antiproton storage ring and antiproton production, etc., and getting into the game of pbarp, that I began frankly to shift my own personal focus to the question of what is possible and what is worth doing beyond the domain of 2 TeV pp that would come at Fermilab. I was certainly going to be part of that pp experimental program. I was a charter member of the collider experiment CDF, and was a proud co-discoverer of the top quark in 1995.
But already at that time I could see that while, you could hope that the Tevatron would have a sure base for discovering the top quark, it wasn’t terribly predictable that it was going to be able to discover anything beyond that. It was tantalizingly close to having enough energy to find what some conjecture might be the mass scale of the Higgs boson. Even in retrospect, I think it would’ve been problematic to ever find the Higgs with the Tevatron, for a couple of reasons I could go into.
So, I began to ask myself the question, what is the next step that it would make sense to try to take in this thing? I came to substantially exactly the same answer that Bob Wilson did. He called it a Desertron. It’s the idea that you identify the lowest-cost basis way to make a much higher energy hadron collider. Most especially you minimize the cost per TeV of the circular ring of superconducting magnets.
The logic is simple. A magnetic dipole bends a beam of protons in a circle with a radius R[km] = E[TeV] /.3B[T]
So, if you want to increase the collision energy of a future hadron collider you can either increase its circumference or you can increase the magnetic field of the dipoles.
If you are smart, you don’t choose the magnetic field based on a site that where you’d like to build it and a corresponding circumference. The cost and complexity of superconducting magnets increase non-linearly with field beyond the ~4T of the Tevatron. Magnets with 6 T field (like those for the design selected for SSC long ago) cost more than twice as much as magnets with 4T field (like the ones built for RHIC). And magnets with 8 T (like those for LHC) cost twice as much as those with 6 T. Push to higher field than 8 T and you must use Nb3Sn superconductor, which is 10 times more expensive than the NbTi used in all colliders to date. Instead you should choose the dipole field corresponding to the lowest magnet cost/TeV - ~4 T - and look for a site that’s big enough for the collision energy you want.
In 1983, fresh from the discovery of the weak bosons, it was clear that there was a very compelling reason to expect that the Higgs boson did exist. Theorists could not predict its mass with any certainty, but they could say that its mass must be less than ~1 TeV or the whole scheme of spontaneous symmetry-breaking of the electroweak interaction broke down.
[End Session 1]
[Begin Session 2]
Peter, let me just do my introduction so it's clear in the transcript that this is round two. OK. This is David Zierler, oral historian for the American Institute of Physics. It is August 2, 2020. I'm so happy to be back with Professor Peter McIntyre. Peter, thank you so much for joining me again.
Okay. So, let's pick up on where we were last time. The last items that we discussed were we were talking about the top quark and Rubbia in 1978. And then you started discussing Bob Wilson's work and the excitement over the Higgs boson and working in those energies and identifying a place where a high-energy facility might possibly find the Higgs boson. And I guess my first question is, this word "Desertron," so let's start there. Where did you first encounter this word and what does Desertron sort of convey?
I'm not sure about this, but I think the term was actually coined by Shelly Glashow. He has always been a bit of a wit in our game, and it characterized with some humor one of the dimensions of Bob Wilson's vision for the question of how we reach beyond the Nobel discovery of W and Z that the United States missed by its own lack of action of the weak bosons. And how we pushed for what was already, at that point, a vision that was clearly in the crosshairs of the standard model, was the Higgs boson, which would be the origin of electroweak symmetry breaking. That was a well-characterized mystery; and trying to solve that mystery within the context of gauge theories led inexorably to the use of the Higgs mechanism to give rise to that spontaneous symmetry breaking. The Higgs mechanism was devised by theorists, not in the context of particle physics at all but of superconductivity. It is a very elegant, powerful mechanism within quantum field theory to give an origin to symmetry breaking to the fundamental things that happen both in solid state physics and in particle physics. And, actually, in many other regimes, as well, in different contexts. In this case, the understanding had an intriguingly predictive element to it. There were very good reasons to believe that it could not have a mass less than about 125 GeV. But the upper limit would depend upon how the Higgs sector materialized as a spectrum of new particles, whether it was one Higgs or a Higgs plus a doublet, etc. The Higgs mass scale could be as much as ~1 TeV but no more. And so, following the Nobel for W and Z, the brainstorming focused on how to access point-like mass scales up to TeV with high luminosity to try to find this new Higgs sector.
The collision energy required in colliding proton beams and all of the thinking for that purpose focused on proton-proton collisions, not on antiproton-proton, which I had invented and which had been used to find the weak bosons, because it was felt that this would require a very high luminosity at that energy in order to find the Higgs. At that time, all but a very few accelerator physicists thought that pp had really no prospect of reaching the higher luminosities of the order of 1032 cm-2s-1. That's the measure of the event rate of collisions per second that would produce a new particle with a certain cross section measured in cm2 in the collisions. That perception led the world of accelerator physics to that they would need to build a double ring (with twice the magnet cost compared withpp) to make proton-proton colliding beams in order to make the beams sufficiently intense to achieve that high luminosity. The gentle irony that unfolded over the following decade and more, really almost two decades, is that pp colliding beams at Fermilab in the Tevatron in fact got better and better and better until, guess what? The final runs ofpp, before the switch was finally flipped and Fermilab ceased to be a laboratory doing collider physics, was 1032 cm-2s-1!
No one except me and two other people at that time believed that would ever be possible.
Who were the two other people, Peter?
Bob Wilson and Russ Huson, both from Fermilab.
Now, are you writing, are you presenting, are you sort of trying to get the gospel out on this realization?
No. It seemed so hopeless the first time to convince folks to grudgingly acknowledge that pp colliding beams could give you luminosity needed to discover the W and Z. It was that much again hopeless for them to even contemplate that pp could ever produce such spectacular luminosity to discover the Higgs. It's a very peculiar kind of world we live in. At any rate, so the push, then, was to try to conceive of how to make these very high energy pp colliding beams. That leads into a theme that is replaying again in the present day: the interplay between dipole field strength and ring circumference that I explained earlier. In that era of the 1980s, the tunnel cost was perceived to be quite high (because the national labs hoped to build a next collider at Fermilab, where tunnel cost would have been high), and the superconducting magnet cost had come down somewhat with the development of the superconducting ring for Fermilab for the Tevatron, and the follow-on electron-proton collider HERA in Hamburg. So, a coalition of national labs chose 5.5 T for conceptual designs for SSC. And DOE ultimately adopted their design, which required a tunnel of 90 km circumference.
Bob Wilson had a different view. And I would say with honesty, but it might seem hubris, that I independently came to the same conclusion as Bob. Bob felt that the more promising approach was to open one's view of where to put the machine and seek a site where the cost of the tunnel would be absolutely minimized, and then be guided by that circumference in the choice of a magnetic field. That led to a magnetic field of ~3 T. His choice was actually 2 T, and the only place you could, at that time, contemplate finding a big enough site in the United States was in the desert. That would require a tunnel of about 250 kilometers in circumference, and you really needed a place that was both very flat and over a very large expanse with affordable land where you could, in principle, make the tunnel using the much less method of cut-and-cover rather than a bored tunnel.
So, Peter, what were some of the obvious contenders from the beginning that would fit this criteria?
There were really only two that surfaced, one that he surfaced and another that I surfaced. One would be out in one or another patch of desert in the west. There are several specific places. And another that I identified and actually led to one of the two candidate sites offered to DOE by Texas for the SSC as it was finally configured, and that was out circling around Amarillo, Texas, which is a comparably flat area called Llano Estacado, a very, very flat high plain with nothing but oil fields in it (laughter).
So, Peter, an extension of Fermilab was a nonstarter as far as you were concerned, doing this in Illinois?
For a cut and cover tunnel as it was a non-starter. You should first realize that the tunnel for the Main Ring at Fermilab—and the Tevatron was put in that same tunnel -- was built using cut-and-cover. That simply means you're digging a ditch down to the level where you want the ring to be sitting. The site must be very flat and the site at Fermilab on that scale of 1 km radius is very flat. The tunnel at Fermilab is 20 feet below grade. Then you just excavate from the surface, erect a hoop of tunnel liner segments in the ditch, and cover it up. That worked for Fermilab for the 1 km radius Main Ring tunnel, and it had low cost. Wilson understood that the right way to design a Higgs-capable collider is to try to find a site where we can do cut-and-cover—the tunnel costs for cut and cover is a third of the tunnel cost for the lowest-cost bored tunnel, where you take a tunnel boring machine and you tunnel through one or another form of competent rock or soft ground deep underground to make a tunnel. Wilson's logic was to find a sufficiently flat site for cut and cover tunnel, and adopt a magnetic field of ~2 T. That choice led him to a very elegant form of superconducting magnet which he dubbed a superferric dipole. Superferric simply refers to a magnet in which the magnetic field is generated by a superconducting winding that is closely coupled within a steel flux return and operated at a field at which the steel is un-saturated. Steel has a wonderful property of ferromagnetism in which the the amp-turns of current required in the winding is only what is required to drive the magnetic flux across the aperture of the beam, but the steel channels the return of that magnetic flux around the return path between the two poles. So, the price you pay for superconductor is only ~1/4 what you would pay in a dipole in which the flux had to return pole-to-pole through vacuum. Up to about 2 T of magnetic field, steel has a permeability of the order of 7,000, which means it only takes you 1/7,000th of the amp turns for the part of the path that goes around through steel to produce 2 T in the center. At the other extreme of that is a magnet like the 6.5 T ones developed for SSC and the 8 T ones built for LHC. They use a collared coil of superconducting niobium titanium arranged in a kind of Roman arch, in a cylindrical geometry, so that the magnetic flux must return in a permeability of 1. So, it requires much more superconducting wire in a magnet than in a superferric dipole. Wilson's rationale was to set the field at 2 T and make a very simple-to-build magnet, with very little superconductor required, but you would need clearly three times longer circumference to the tunnel, and three times total length more total length of the superconducting magnets.
The tradeoff between field strength and circumference was seen very differently by all the rest of the HEP community. To them, you want to put this in an interesting place like the site of Fermilab or the site that was chosen ultimately for the SSC, very close to Dallas, so that it's close to an industrial center, it's close to a major international airport, all the things physicists like to have around them to do their work. But the sites near such cities typically required a deep tunnel in competent rock and required a tunnel to be excavated using a tunnel boring machine. So, they reasoned that you needed to make the tunnel circumference as small as possible because the tunnel was going to be a major part of the cost of your project. That was the big dichotomy that was on the table. The only people who were pushing low-field solutions because of the virtue of the superferric magnet were me in Texas and Bob Wilson at Fermilab. Also, Russ Huson, who was the head of the accelerator division at Fermilab and had his own ideas which paralleled closely my own. Within six months of this ferment of ideas, I persuaded Russ to join me here in Texas and join our faculty. The two of us as a duo pushed forward a concept for a 3 T superferric magnet which then required a 150 km circumference tunnel.
Peter, I want to ask, at this stage when you're beginning to become conscious of budgetary issues, how do you know what are reasonable numbers to work with? Do you have any sense, are there any studies, do you have anybody in Congress or elsewhere who's saying, you know, X amount of dollars is reasonable and doable, but X amount of dollars is totally off the wall and it's a nonstarter? Do you have any idea what numbers you're working with that might be viable in terms of getting this thing off the ground?
We did at the time. In those days' dollars in the context of what the government spent money on and what was viewed as in line with its costs and whatnot, one billion dollars was considered a tenable cost that would have made this a no-brainer. Two billion was pushing pretty hard. Three billion was very problematic. A parallel project through that whole period that was the International Space Station.
ISS was originally proposed at a cost of a few billion $, But by the mid-eighties, its projected cost had grown to $10 billion. It ultimately cost $25 billion. Just at the time when the SSC was killed in 1993, the Space Station was at a very critical juncture where its cost had once again risen, and Congress was in the mood that they were going to kill something in the multibillion-dollar class.
And is your sense, is this sort of a post-Cold War—there's a much smaller appetite for supporting these major projects and it's a zero-sum game, it's either ISS or it's SSC? Was that your sense?
Well, at a certain moment it came pretty close to that. If the SSC had not been killed—the ISS was really on the ropes at that moment, and it was at a stage where it took a presidential initiative, which Bush gave, to try to push that over that hump to save it. But the ISS was very healthy in Washington in the early eighties when the first efforts were being made to propose the SSC. All elements of the government were solidly behind the ISS at its then-projected costs.
But the ideas for SSC came at an awkward moment. President Reagan was trying to trim the budget, and he had just given a presidential directive to all federal agencies that there would be "no new starts" of major projects. It was the one point in his administration when he was determined to try to trim the budget because he ran us, after all, into what, in that era, were historic levels of deficit. That was the context within the Department of Energy, so discussion about a supercollider was not welcome.
Ones that did not have an obvious military component, we should specify?
So, when Wilson went to Washington, when I went to Washington trying to get traction on notions of how to make the supercollider with the cheapest cost it could possibly be, the reaction was: It's not going to happen in the foreseeable future.
And when you say, Peter, you're going to Washington, who are you talking with? Strictly DOE people? Are you testifying on the hill? Are you at NSF? Who are the people?
Well, initially it was strictly within DOE, but for the reasons I just gave it soon became clear to me that pragmatically this was simply not something that was going to be judged on its merits. DOE was happy to try to foster a modest program of technology R&D to try to quietly move forward at modest cost the development of magnet technology to make it a bit clearer what was possible for superconducting magnets, for 3 T magnets and for 6 T magnets.
There came an interesting episode that's a bit illustrative of how DOE works. Bill Wallenmeyer, the head of high-energy physics in DOE, called up the national lab directors and made an overture to them that they should have a very quiet workshop, out of the public view, to discuss putting together a modest technology R&D program that would shed some light on those questions; a very reasonable thing for an agency to do. Panofsky offered to host such a meeting at SLAC. This overture triggered strong ambitions at each of the laboratories hoping that if this did result in something it might be in their backyard, either on Brookhaven or on Fermilab, for where this thing might be built. And so, there was a certain naturalness to have the meeting at SLAC, where there would be no question that it would be built nearby. I mean, after all, the San Andreas fault had a lot to say about building large circumference tunnels in that area. So, it was a neutral ground place to do that meeting. I had been doing my best to put forward ideas for a superferric SSC and there were folks at each of the national labs looking at high-field magnet designs. To them it only made sense to aim for a magnetic field of 6 T or 7 T. Both Brookhaven and Fermilab had devoted huge efforts to develop such magnets and considered that their territory in accelerator technology. So, they scorned the notion that Wilson, even though he was Director of Fermilab, had been putting forward this renegade low-field design.
Wallenmeyer’s meeting was framed to pull together the advocates of the 6 T and 7 T designs. And the meeting was planned with absolutely no word that they were even having this meeting filtering to me.
But Russ Huson was allied with Bob Wilson in developing the superferric design, and his own choice of field was 3 T. Because he was director of Fermilab’s accelerator division, he knew that the meeting was happening. He and I were in contact and discussing back and forth our respective ideas, which were closely similar. And so, when he told me about this meeting, I felt that an opportunity was about to pass in which the government was responding in its way to the need for a future machine, but it was about to be captured by an ensemble of interests that were entirely focused on what I believed was a dead end for the project, because it would make it far too expensive.
So, you saw, Peter, that this was going to balloon well past that 2-billion-dollar threshold?
Oh, there's no question.
It would have been 3, 4, 5 billion at best.
Right, right. So, this is important because this sort of throws cold water on the idea that some people have said that this was viable at 2 billion and that the cost overruns up to 8, 9, 10 billion, that was sort of a surprise after the fact?
You're saying that this was obvious even at the conceptual stage?
To me, yes.
And how important was that for you to get the word out both to colleagues and to people who were pulling the purse strings that either this needed to be reined in one way or this is DOA from the beginning?
Well, most people in the scientific community regarded it as DOA period because of Reagan's directive. And most people in the government also viewed it as DOA because of Reagan's directive. Fixing that problem is a later chapter I'll come back to if you wish. But it became clear to me that if I was going to get anywhere, I would need money, and to get money was going to be problematic if they were about to have a meeting at which they were going to be exclusively focused on high-field magnet technology. So, leading up to that timing, I realized that it was going to be necessary to form a serious enterprise here in Texas.
Here begins a particularly Texas dimension to this story. I was sitting one day in our departmental office talking with our department secretary Barbara, unburdening to her about my frustrations in trying to get traction for my ideas. It was clear to me that I faced a ‘chicken and egg’ impasse: to get credibility in the fight for limited DOE $, I would need to already have in place a credible base from which to develop and test superferric magnets in Texas! Otherwise I would be in the position of trying to persuade one or the other national lab to abandon its own designs and adopt mine. Barbara was listening sympathetically to all of this, when Tom Adair, one of my colleagues, came into the office. Tom is an interesting character. He's a native Texan, and an atomic physicist by his research, but had been our department head in the past and was broadly savvy about all things Texan. Also, he is an Aggie, he was a graduate of our university, and he knew the world of wealthy Aggies (and there are quite a few wealthy Aggies). Tom came in just as I was saying all this, he listened as I was unburdening myself, and he said, " You really ought talk to George Mitchell." I said, "Who's George Mitchell?" Tom said, "Well, he's an Aggie, first and foremost, and he is very wealthy, both as an oil and gas developer and as a real estate tycoon in Houston. And he has more vision in his left brain than all the rest of Aggies that are alive (laughter). And he would just love this." And I said, "Well, that's an interesting idea. Maybe I should."
I went back to my office, I've always been a kind of do-it-now guy. I called directory information and asked for the main number for Mitchell Energy and Development, I was switched around by secretaries and explained my name and what I was calling about, and that I'd like to talk to Mr. Mitchell, please. Now I had no background in dealing with people who are very busy in companies, so I figured I would get a runaround for weeks or months trying to reach him, but I decided to try. Well, after about a three-minute wait on the phone, a voice came on and said, "This is George Mitchell. What can I do for you?" I told him my story, my two-minute elevator speech, as you might call it. He said, "Well, I can see maybe why you're calling me, and it sounds like maybe you would like to come down and discuss this in more detail." And I said, "Anytime you like." So, a couple of days later I drove to The Woodlands, which is this sort of city on the north edge of Houston that he built, and had a memorable afternoon talking to him about all this. I brought along blueprints of magnets and geology of potential sites and ideas about tunneling that I had worked up with civil engineers here at Texas A&M. I told him I wanted to bring Russ Huson to Texas, if I could manage to recruit him, and that I would need to equip a lab to build and test superconducting magnets. There on the spot George committed 1.5 million dollars to give me kind of enough seed to plant and called up the president of our university and asked him to please treat me kindly. Within a week, we had launched the founding of the Texas Accelerator Center, which was a four-university collaborative based there in The Woodlands, Texas in a very nice building that George donated for the purpose, and we began setting up our laboratory. Within a month we had Huson on our faculty and as director of the accelerator center, and we had a solid technical design for a 3 T superferric dipole for the SSC. We had one month to go before the SLAC meeting.
I began calling, first to Panofsky, then to Wilson, then to each of the other lab directors to seek the opportunity to speak at that meeting. Technocrats in national labs have a way of saying something to you that is genteel in most cases. In the case of Bob Wilson was not genteel, it was blunt: while you have some good ideas, this was not a context in which it was really welcome for you to be given the latitude to put them forward because this was a meeting where the lab directors were going to be talking with the head of the Office of High-Energy Physics to try to pull together a package of money to fund high-field magnet development. And the context they were giving it was for 6 T to 8 T and pushing for more advanced technology and thank you very much.
So I was, as it were, disinvited to this meeting. I thought about that and what one can do in such situation. In the end, I bought a plane ticket to San Francisco. I knew when and where the meeting was going to happen. And I materialized at the appointed time and there was a closed-door session where they had just begun the meeting. The national lab directors were there, the head of high-energy physics was there, and the various second- and third-tier folks were there, etc.
And, Peter, officially or nonofficially, what extent are you representing Texas?
Well, that will become clearer in what I'm going to tell you.
They had a secretary outside the door, a dragon lady to keep riffraff away. I explained who I was and why I was there, and that I requested time to speak to this meeting. She said, "I'm sorry. This is a closed meeting that does not allow visitors or spectators or people to come in and give talks." I said, "I think you'd better maybe ask Dr. Panofsky to step out for a moment because this is important." So Pief stepped out and I said, "Pief, what you're doing here breaks federal law. There is an open meetings act. You are gathered here to discuss the allocation of 20 million dollars." That's the number that Wallenmeyer had put to what he felt he could spring out of his shirt cuffs, so to speak. "You're discussing the allocation of 20 million dollars towards a vision for the future and you have invited people to talk about what they believe are meritorious ways to do that. And I am here with a meritorious way, and I want to present my ideas as a part of this dialog because I believe they are the best of the ideas that are being put forward." Pief said, "Peter, this is among the national labs." I said, "That breaks federal law. You're talking about allocating federal funds here. I'm coming here representing a new laboratory, not a national laboratory, a new laboratory in Texas, and we are keenly interested in this. We have ideas to put forward and we believe they're better than your ideas. This is not the time to waffle about." I said, "So, I would then ask that you either disband the meeting or invite me in." So, he went back in the room, talked for a brief period with the other lab directors and Wallenmeyer, and invited me in. I gave a half-hour talk, and out of the push and the pull of that meeting and things that then happened afterward, I was invited to put in a proposal. We put in a proposal for 3-1/2 million dollars. It had the million and a half from George and another million from Texas A&M as cost sharing that was offered along with it. After some pretty tough back-and-forth wrangling, it was funded. That was the birthright of the Texas Accelerator Center. That carried us through a 3-year period in which, by the end of Year 1, we had built and tested a first one-meter prototype of our magnet; after Year 2 we had transferred this technology to General Dynamics in San Diego; and after Year 3 they had built three full-length dual dipoles. Full length meant 100 feet long, the longest superconducting magnets ever built by man, still the longest superconducting magnet ever built by man. Each of those dipoles had two bores in it, and they worked to specification. So, we proved that the superferric magnet is a simple technology, and it met specification for use in a collider, it had the fuel quality that it needed, it went to its full field without training.
Now for the best part: 10 years later, after SSC was approved as a project and DOE selected the 6.5 T dipoles for its rings, when the SSC was finally killed, the national labs had still not achieved that same success with the 6.5 T dipoles.
What was Panofsky's reaction to this—and other lab directors—as you were demonstrating that these projects were not only viable, they were on budget and they were doable?
Anger, vexation, and respect.
So, we moved forward with building and testing the superferric magnets. I gave a progression of talks advocating what we were doing. But there was still no project to actually build a collider. Secretary Herrington of DOE had made a visit to OMB and was told, don't even think about showing up with any kind of project; you're under a no-start order, just go away. So, there was really no context that anyone could go further. At that point, I came back to Texas and felt that the only way forward would be to build enthusiasm within Texas and try to create a path by which we could take this directly to the White House.
In 1982 our governor at the time, Mark White, convened something that was new for Texas, an R&D advisory board for the state government. He did this to build an appreciation in Texas politics of the value of science, like a Texas version of what Vannevar Bush did for the nation long before, that would articulate the opportunity and the importance of research writ large for Texas, and justify a sheltered place in the way the state budgets money. Now, that might see a no-brainer to people like you or me. It was not a no-brainer to most Texans. They had to be helped to see what science could do. The inaugural session of the Texas R&D Advisory Panel was announced in the newspapers with some hoopla. Reading about this, I felt that it could be an opportunity to put the supercollider forward in Texas to see if there was some way to energize Texas politics to support it. So, I requested an opportunity to give a presentation to their inaugural meeting and I got it. I gave about a 20-minute talk about particle physics and the accelerator technology that we had pioneered in Houston and how it would enable a new generation of atom smasher that had the credible potential to discover this Higgs boson. One of the folks who was a key figure in the Panel was Ross Perot; that's a name that will be familiar to you. Another one was the chancellor of the University of Texas system, Hans Mark, who was a physicist himself. Hans was former Secretary of the Air Force, very much a political animal, and he, at that time, was the chancellor of the UT system. I had never met him. He was sitting in the front row of the meeting. My talk was just before lunch, and Hans came up after at my talk and said, "You know, you and I should have lunch together." So we went for lunch and he said, "This thing could happen, but it's going to take some real orchestration. And not only can it happen, it can happen here in Texas."
This was of course exactly what I was hoping to find, a bird of the same feather but with a lot more plumage than me to come to the same conclusion. So, we had our lunch together and laid out an agenda that we then approached as a dynamic duo over the next year, in which he arranged meeting after meeting to take me with him on the UT plane to talk with all the right people. Now that was a treat, me an Aggie professor and there's all this legendary bullshit on the football field between the two places, but on things that are of consequence the two universities work together. So, he would pick me up with the UT plane, we would fly to Odessa, we would fly to El Paso, we would fly to Dallas and Houston, obviously. It seemed that we flew every place under the sun of Texas. On each occasion Hans would set up with the local civic organizations of the high-roller Texans and local politicians for me to brief them on this thing. A beautiful aspect of it is that there were several natural sites in Texas where you could build the SSC. There was a site near Houston, there was a site near Dallas, there was a site circling Amarillo, there was a site in the Permian Basin near Odessa, one near Beaumont. In just about every congressional district of Texas you could find a workable SSC site. We approached this from a bottoms-up strategy of enthusing the local folks with the vision that this could be in their backyard. It could certainly be in Texas and it could be, in particular, in their backyard. As we went on each of these trips, it gave me an opportunity to learn more about Texas and the way it works politically and also to meet people whom I would never have met otherwise in the front half of my career. One experience on every trip that repeated itself was that one or another person from each of those settings would come up to me afterwards and say, "Dr. McIntyre, I understand what you've been saying, I think it's wonderful, and I'm for it and we're going to make it happen. I just want you to understand this place right here, this is God's country." Those were the words. And those words repeated themselves in every part of Texas.
What's the message there, Peter? What do you think that really means?
There are layers of pride and layers of loyalty to people who have managed to become leaders in different parts of our state, and it's probably true in any state—there are these layers of pride and loyalty that, if you can find ways to tap them, are very powerful. And they transcend politics in the sense of right and left. I'm a dyed-in-the-wool liberal Democrat; proud of it. But that in no way got in the way of me carrying this message effectively to these folks, many of whom were as far away from me as you could get in the political spectrum, because we were tapping common interests that we shared. And if we could just get there more often in this world, we could get a lot of things done.
Out of the Hans-and-Peter traveling show sprang an internal SSC site competition that the next governor (Bill Clements) initiated here in Texas. You probably didn't even know about that from what you may have read about the SSC project. A year before there existed a DOE mandate for the SSC as a project, there was already a project here in Texas that the state had committed money to and invited the regions of the state to submit proposals for possible sites. In parallel with that, one of the places he took me was out to Odessa and we met at the Petroleum Club with a number of the high-roller oil and gas men of the Permian Basin. There was a very particular reason for that meeting. He said, "Gentlemen, this is not a federal project. This is not something we have the opportunity to go make a case for at this time. That's the unfortunate reality. For this to happen it is going to require a presidential decision. It's going to require that President Reagan tell the Department of Energy to move forward with the project, and that's flat in the face of his present budget-cutting policy. To persuade him to do that is going to require a significant piece of persuasion. The only person that I can see doing that is the Vice President. And so we want to make the case to the Vice President and sell him on the vital importance of this as a flagship for American science and an opportunity for President Reagan to be recognized as the president who initiated it, just like the space race for Kennedy, and to infect him with this. So, we need to persuade the Vice President. And your colleague out here, his son, could be instrumental in persuading him." And they looked at one another and they said, "You talkin' about W?" Hans Mark said, "Yes." They said, "Aw, come on. You really think that he can do that?" "Yes. No question he could if he chose to do it. He could open that door and set up the opportunity for you to have a briefing session with the Vice President just by asking." Said, "Oh, shoot. Well, son of a gun. Well, let's go put it to him."
Now George W. Bush was at that time an oil and gas lease salesman out in the Permian Basin. You can read about that other places. The oilmen made the overture to Mr. Bush, and he went to his dad and explained that these folks from the two flagship universities wanted to talk to him about this project for a hadron collider. So, George H.W. Bush agreed to meet with us, and we briefed him in the West Wing.
So that was quite literally the birth of the supercollider.
Peter, how important was it in talking to the Vice President to excite his interest in what the science could mean for this?
Absolutely critical. George H.W. Bush was a very serious guy. He had the complexity of the world in his head. He asked a lot of questions. He asked questions about, is this just a Texas thing? What does this mean for the bigger house of science? And I had answers for him that I had thought through, because I wanted to be well prepared. What is the potential that it might fail? What could make it fail? What is the potential that it might cost a lot more than what you're telling me, and how can those risks be reduced? I mean, they were very to-the-point questions, each one in turn. It was not lost on him that there were not only viable but extremely attractive sites for the SSC in Texas. That was by no means a pivotal thing for him, but it was an important thing. And, indeed, the site that was ultimately chosen, the one just south of Dallas-Fort Worth is, in my opinion, the very best site that could've been chosen for the SSC, either with a 90 km circumference or twice that for the superferric version. That's another story. But all of those ingredients—I presented to him a map of that exact Dallas site that later was chosen for the project by DOE's own committee.
I presented to him both our technology solution to this and the high field magnet solution. I showed him the successful test results from our magnets. I said to him forthrightly that I felt there was serious risk that it could potentially fail if the high field solution were taken, but here is this low field solution which we have now proven. Here is the magnet right here. You can go kick it down there in suburban Houston. The briefing lasted maybe 40 minutes total. At the end of it, Vice President Bush turned to Fred Kaduri, his senior aide, and asked, "What do they think about this over at Energy?" Kaduri said, having done his homework properly, said "Herrington says it's a solid project, it has very strong science behind it, it's a really great thing, but it's a nonstarter because the President doesn't want any new starts." And so, he said, "Well, put together a briefing paper for me for the President and I'll go over and talk with Herrington and we'll see what we can do." That was it. The outcome of that meeting is that, two weeks later, President Reagan had on his desk a one-page proposal from Secretary Herrington for this project and he said, "Well, go make it serious." So, the birth of the SSC as a project was in the West Wing of the White House on that day. And I can come up with the date for you. Indeed, I have a photograph of me doing the briefing to Vice President Bush.
Oh, I want to see that photograph badly. I gotta see that.
I can send it to you.
Okay. Peter, once this was a—done deal is not the right word—but once you saw that this really got off the ground, what was the immediate reaction from the other national laboratories in general?
They were astounded. Their view had been that the magnet R&D program was giving them an opportunity for a gradually growing budget of technology R&D to groom technical solutions over a period of three or more and hope for a greener day in Washington when there would be a window of opportunity to make a proposal for a new project, and then they would come along with the project. They were stunned. They had no idea that it would be conceivable to enthuse a sitting president with a nutty thing like the supercollider.
And your sense was not that with the SSC as a viable proposition would pose existential threats to the long-term viability of a place like Fermilab, for example. That was not your sense? This was like, in a rising tide, all ships will go higher kind of thing?
Frankly, that was not something that I gave cognizance to. I did not feel a loyalty to Fermilab as a place and as an organization. It had, in effect, turned its back on me three times going, so there was no reason I should feel such loyalty. And the thing that, after all, we are all in the game for, Fermilab and me, everybody else in that process, is the science. If you're not focused on the science, you should go home or do something else with your life. And the science was—in my considered view of all the work I was doing with open eyes and no bias against Fermilab—the science dictated that this needed to be in a place where tunnel circumference was not a driving term, tunnel cost was at an utter minimum, the lowest cost technology for magnets could be used to best advantage, etc., and that was not Fermilab.
Did you have a sense, thinking even more broadly, that this wasn't just good for science, it's what needed to be done for the United States to retain its leadership in high-energy physics generally?
Yes. I was massively frustrated at seeing, with admiration but also vexation, the ideas that I had championed for proton-antiproton colliding beams brought to fruition by Rubbia and van der Meer and colleagues at CERN while Fermilab sat on its hands. The SSC seemed to me a real opportunity where the US could take the next big. Again, the technology leadership was here, completely viable sites were here. When SSC died from mismanagement, CERN built the LHC in the LEP tunnel, which mitigated the tunnel cost issue for them, but it also required them to push to the utter extreme the magnetic field performance you could get out of niobium titanium superconductor. They had to subcool the magnets to superfluid helium temperature in order to get to the 7 T that was required to reach 14 TeV in the LEP tunnel circumference. They did pull it off, to their great credit, and they did a spectacular job of manufacture of the magnets, and with the sole exception that when it was being commissioned the magnet ring nearly self-destructed because of bad splice joints. They fixed that problem, and LHC has worked very, very well for the house of physics ever since. But I felt keenly that this next opportunity had everything going for it here in the US.
What's the next step at this point?
In the progression toward the SSC? Well, picking up the story at the point when the SSC became a DOE project, we put forward the case for the superferric SSC and its full merits. The national lab team did the same for the 6.5 T design. DOE commissioned a working group called the Central Design Group (CDG) , based it at Berkeley, and put Maury Tigner in charge. Their task was to evaluate the propositions for the 3 T and 6 T designs for SSC and make a down-select to a single choice for the project. That was a very important decision that could make or break the project. At the Texas Accelerator Center, we obviously focused on developing a compelling case for the superferric design. The CDG articulated a very thorough agenda for the basis on which the costing was to be done, and they cleverly wove into that agenda what ultimately was the death knell for our efforts. They required that you had to do a costing exercise for three different sitings for the SSC. It was a technocrat's dream. They articulated three sites that would characterize a very low-cost site that was far from cities where tunnel cost would be absolute minimum (cut and cover); a medium-cost site that was pretty close to a city and they even told you the tunneling depth, etc; and then a high-cost site that basically you could build practically under a city. Then commenced a David-and-Goliath kind of a competition. The thing that did us in is that we showed that the total project cost would be utter minimum—I mean, like, factor of 2 minimum, using the low-cost site with the superferric technology. That was obvious to everybody from the outset. We showed that the superferric solution was by far minimum cost at the medium-cost site, which was, in all respects, almost exactly identical to the site there in Dallas-Fort Worth that was chosen for the project. So, we had a site at that exact same location, , with twice the circumference, that was beautiful for this project. It stayed entirely within the Austin chalk, which is nature's most perfect tunneling medium for tunnel boring. Austin chalk. is a soft consolidated limestone. You can carve it with a pocketknife. The tunnel construction contracts for the 30 km of the SSC tunnel that was bored at that site are the cheapest tunnels ever made by man today, still, 30 years later. So, the superferric design was far the lowest cost at the low-cost site for the total project cost. Ours was, by a substantial margin, the lowest project cost at the medium-cost site. It was only not the lowest cost at the most expensive tunnel site that had to be in—for example, Fermilab. You put it at Fermilab, you would have to tunnel in the dolomite, which is hard limestone. It's the bones of the earth—it's wonderful to tunnel in as long as you've got a deep pocket. So, in making the down-select decision which CDG did, their memo of decision articulated that this site had to be the lowest cost—to go with the superferric, it had to be the lowest cost at all three sites. And because it wasn't the lowest project cost at the most expensive site, therefore they had to choose a magnet technology that corresponded to the minimum tunnel length so that the project cost would not constrain an open competition among possible sites for the SSC over the country. Their rationale was that the prospect of the site competition for the project would motivate congressmen and senators from every state to support the project, so there should be viable sites pretty much everywhere in the country. It was a wired ‘technology selection’ from the outset.
What do you mean "wired"?
They knew the decision they wanted to get.
And they cleverly found the only narrowly constructed logical trail that would get them there, and they did.
Are you working with people like Roy Schwitters and Fred Gilman at this point?
Schwitters came along much later. Schwitters sat on the site selection panel of DOE that actually chose the site. But he was not part of the CDG at all. Fred Gilman had a role in the CDG and that carried over into things that he did a bit later.
And what year—let's root ourselves chronologically—what year are we in now?
When CDG announced their decision, we were devastated but we were not surprised. You could see the handwriting all the way from the day they first founded the organization. So I wrote a formal letter of appeal to the High Energy Physics Advisory Panel (HEPAP) saying that I believed that this process had reached a wrong decision, wrong for the interests of trying to get this project built in the most affordable way, wrong for the most reliable way to build the SSC. HEPAP is the highest peer advisory group in the field of high-energy physics. HEPAP responded to my letter by setting up a special subpanel chaired by Burt Richter which meant, again, at SLAC. So, once again, at a pivotal moment in this thing I returned—Russ and I returned to SLAC. Richter did a thorough job of analysis on this from his point of view and came back with a masterful way of moving his panel. It was a very august panel, had Sam Ting on it, Jim Cronin, so it was a real Nobelist exercise. They came back saying that there was certainly a case to be made that the superferric option for this project would be both the lowest cost and the most risk-immune way to proceed, but the CDG had followed its agenda faithfully and reached its conclusion with a number of complex ingredients in the picture besides just the ones that we were focusing upon, and therefore there were not adequate grounds to overturn its ruling and throw the project into limbo. So that put the nail in the coffin. The SSC thereafter had a 6.5 Tesla magnet ring. Two things ultimately killed the SSC: that decision for expensive magnets, and the dreadfully broken project management that DOE put into place to run the project. It was not that it's a death that you could blame on Congress. We in high-energy physics did it to ourselves by mismanaging the project. There are very few who hold the same view that I do on that matter, so I can only state my own view.
From an administrative perspective, you're never part of the DOE infrastructure; you're always on the outside looking in.
Never been. I've never sat on HEPAP. I've never taken any form of administrative role at a national laboratory other than being the group leader of the team that Bob Wilson gave me to build the cooling ring there in the early days that lead to pp. And I've never had any role in DOE other than to be a reviewer of proposals.
And so, obviously, this begs the question, you feel very strongly about some of these issues, so in what ways did your outsider status handicap your ability to influence the process?
I don't think it handicapped it at all. Indeed, had I been part of the process, it would have hampered me in identifying what is the thing that should be done and how can I best persuade people to do it? My responsibility was only to science and technology.
And so, on that question, as this project begins to take shape and it begins to seem, at least at that point, more real, are the questions you're asking, do those evolve as well? I mean, to go back to Rubbia and the top quark and where the Higgs boson might be, are the same questions you're asking in the late 1970s, are these the same questions by the mid-1980s as the SSC seems like it's going to become a reality, or are you asking new questions as both the project develops and as high-energy physics develops, as well?
The answer to that changes with time. In the mid '80s, that was very much the theme was very much the one that was motivating the SSC. That was the game in the world for this field of science. It was nuanced. There continued to arise new ideas of supersymmetry and other dimensions beyond the standard model of what was Mother Nature's deck of cards. And a lot of thinking about how, in designing experiments, those new ideas might be probed at the SSC. And there was hope that they might be. So, there was a lot of evolution in theoretical physics and in the development and design of experiments for the SSC and then, when it died, for LHC for trying to not only discover the Higgs boson but then reach beyond it.
To answer your question about what was I thinking about, that was the theme of my thinking through the period from the mid '80s through the early '90s, '90, '91, something like that. For me, it was a very frustrating period because I became nominally part of the team who were developing the design of a solenoidal detector to do the particle physics experiments at SSC. But my heart was not in it. It was a gargantuan collaboration. I did not see a natural way that I could be a constructive contributor to it of new ideas and new ways of making it the best it could be, so I took only a very nominal role in that experiment. Almost no role at all.
I began in the early nineties to ‘think beyond the Higgs’. Discovering the Higgs boson was the central goal of the SSC, and when it died, of the LHC, and everyone agreed that either of those colliders should have the mass reach to discover it (or if they did not find it, to open an even more exciting revolution in thinking). But it was already becoming clear that there was likely another symmetry-breaking process at yet higher mass scale that underlay the Standard Model, and that it might well prove to be beyond the grasp even of SSC. There were a very mixed bag of phenomenologies, sharing many elements in common, described by the name supersymmetry (SUSY). Some true believers would lead you to believe you might even discover SUSY before you found the Higgs boson. Others predicted that the energy scale of SUSY symmetry-breaking could be beyond the reach of SSC or LHC, indeed it might be at an energy we could ever make at a collider. That, alas, appears to be the case in our physical world. Supersymmetry continues to evade discovery at LHC at its present wonderful luminosity. So this led me to shift my focus toward asking how one could reach to even higher energies. And I began looking at how one could most effectively build very high-field magnets to push to very high energies and something that you might consider a realistic tunnel circumference. I devoted altogether 20 years of my life to that, developing technology for very high-field superconducting magnets, methods to handle the Lorentz stress, which is a major pacing element of pushing to high field with superconducting magnets. The Lorentz stress in superconducting windings of magnets increases like B2 and by about 16 Tesla it reaches the limit of strength of the structural materials that are holding the magnet together. like a slightly controlled clockwork that's about to spring apart. So I pioneered techniques of stress management to extend what is possible in collider magnets with that up to about 16 Tesla.
Peter, is this related to your tenure as president of Accelerator Technology Corporation?
I founded ATC in 1987, and I founded it for a couple of purposes. I could see some practical applications that had the potential to come out of some of the things that I had managed to do and, indeed, I obtained held patents on those. And I could see how other applications might be feasible. I also became cognizant of the potential and the SBIR programs to provide modest seed funding to develop new technologies that had promise for addressing the technical requirements of things that were pacing one or another area of interest of each of the federal agencies. The opportunities for funding from SBIRs are to some degree orthogonal to the opportunities that were favored by the basic science programs at those same agencies. But SBIR is only accessible to for-profit companies. So, I founded the company, negotiated a link of it with Texas A&M that legitimized me serving both as ATC president and as a Professor at the university. I have managed to conduct a sort of a double-breasted pattern of research that's focused towards the research end of things through my university group and toward product-driven applications through my company. It has been a very mutually beneficial approach that's enabled me to develop and prove out quite a number of technical advances that would've been problematic to do purely under the one or the other of those programs.
Has ATC been commercially viable beyond the value of what it's been able to do for your research as a professor?
Only in a narrow respect. We have done subcontract work for other companies. We have developed a few products in biotechnology and in medical technology, but it's not yet what I would call a sustaining for-profit company – so far it shows only a modest net return on its quarterly balance sheet. It produces products - it's not merely a flea on the side of the federal government.
Just to complete the narrative of the SSC, at what point do you sort of step back because you see the writing on the wall of where this is headed?
Well, under the management of the SSC as a project that was set up, it was crystal clear to me from virtually that DOE set up the management, and it remained crystal clear to me, that there was really no place in that for me. The core choices made for the main technical parameters of the collider were utterly wrong-headed:
Yeah. Peter, this is such a valuable insight, because so many perspectives on this cottage industry of the obituary of the SSC emphasized the economic and political shortcomings, which obviously are there, but the theme of—
That was just a noise term.
There's always that kind of noise term with any big project.
So, my question is, in your emphasis—this is just so incredibly valuable—you've really emphasized that the science wasn't there. So, the question is, to put this in the starkest terms possible—
Excuse me. The science for the project was very much there. There was great science to be found, no question.
No, but I mean the range of choices in terms of how the project proceeded.
The technology choices were dreadfully wrong—
—by the field that they chose, by the aperture they chose. They spent a fatally large amount of money and time going down a trail that was doomed to fail. And, by the time they finally had to acknowledge it, the delays in schedule compounded the impact on cost and sank the project.
Right. All of this seems inescapable, then, as you say, if the political and economic difficulties are always going to be there, if the technological choices were different, your assertion would be the SSC would've gone on to success?
Absolutely. It would've gone on to success as a collider with 6 Tesla, 5 cm bore magnets. It would've succeeded with even less time and cost if they had made the right magnet decision of a 3 Tesla dipole. The only course that could sink it is the one that they followed, which is a 6 tesla 4-cm bore collider.
And so, at the end of the day, you are not laying this at the feet of the bean counters and the politicians; you're saying—
—it should've been the scientists who saw this and did not react accordingly?
That's right. And part of the kind of—I won't call it Shakespearean, but part of the tragic element is that, within the house of science, the rank and file and leadership of elementary particle physicists, people who, both experimental and theoretical, are focused in their work and their achievements on particle physics, had reached a point where there weren't more than a few in the nation who also had a solid understanding of accelerator physics and superconducting magnets. To all the rest, those things are black magic boxes, and they hope that the experts managed to do them right because they want to have them to do their next generation of experiments and test their next generation of theories. They want to have those working machines, but they are not willing to devote the intellectual energy to become expert, to be able to make judgments on the vital details of those complex technologies. That's what you encounter over and over again in this field: the accelerator builders don't know any high-energy physics, and they don't want to know it. They're focused on technology. The high-energy physicists don't know accelerator physics and technology, and they don’t want to know. They're focused on gauge fields. That tunnel-vision is dangerous when you're talking about trying to design a cost-optimized, next-generation facility that will actually work and that has a cost sufficiently low that you can actually get government leaders to agree to invest the public purse for this science. It can lead to tragic mistakes (it did for the SSC) and it well may lead to the end of our field of research.
It also suggests that maybe even something as fundamental as the way that physicist’s stovepipe themselves in terms of their areas of expertise, maybe that in and of itself is problematic, if you have—
It is, very much.
—groups of specialists who can't really talk to each other.
Very much so. They can talk at each other, but the receiving end cannot make any informed judgment by which they can sort which group of experts is right and which is wrong. —This cost the SSC its existence. One group of accelerator experts believed that dipoles with a 4 cm bore tube (through which the high-energy beams have to pass without loss as the stored beams circulate and collide) was sufficient. Another group of experts believed that a 5 cm bore tube was essential – imperfections in the uniformity of the magnetic fields in the smaller bore tube would cause subtle but fatal kicks to each proton as it traversed the ring for billions of orbits during one day, and the tiny kicks would increase the amplitude of oscillations in the orbits until the brightness of collisions was lost and the protons would collide with the walls and be lost. The project managers, and the high-energy physicists, all want to leave the room because they don't feel equipped with the depth of understanding to judge the merits of the arguments from both sides. It's takes a thorough knowledge of Maxwell's equations, magnet engineering, and material properties to be able to make an informed judgment. Schwitters had very seasoned accelerator builders telling him both stories. He did not have in his tool kit the developed intellect to make that discerning analysis and the guts to decide which one of them was right. But one was exactly right and one was exactly wrong. It wasn't a thing for taking votes. At HEPAP, the elders of high-energy physics likewise punted, and the lab directors of Fermilab, Brookhaven, and Berkeley largely contributed noise. In the past of our field those folks were drawn from a handful of people who had the kind of dual mastery of physics and technology to make such tough decisions–Burt Richter was such a master, as was Bob Wilson. But those days are alas past. By the time of SSC, those judgements fell to people who hadn’t such mastery and instead sought to find a smooth path that would keep money flowing to the field of research. Therein lay the peril and the downfall of SSC.
Was your sense that Richter ever considered moving on—
Panofsky was, in some sense, the first of them.
Right. Was your sense—did Richter ever consider moving on from SLAC? Could he have been the person to bring this all together?
He would not have done so. He was very much of the SLAC culture. He was happy as a clam there. He was fully fulfilled there. It was his place.
I want to get your reaction—I won't name names, but a certain prominent theoretical physicist once said to me, "You know, so what? We knew the Higgs boson was going to be there, so what's the big deal that we didn't build it?" What is your reaction to something like that?
Well, the obvious answer to them is that we learned a hell of a lot by discovering, not just that the Higgs boson is there, but that it has a mass of 125 GeV, the lightest mass it could possibly have. That was considered to be a remote possibility by most of the rank-and-file theorists through the whole period of time up until it was discovered, including probably your friend. There were a few theorists who, early in the theoretical predictions of the Higgs, wrote a pivotal paper, Dimitri Nanopoulos at Texas A&M and John Ellis of CERN. The two of them wrote a paper in which they showed that, if you simply required a straight-line extrapolation of the running coupling constants of the strong, weak, and electromagnetic interactions out to a single very high mass unification, it led pretty inexorably to a conclusion about the Higgs mass, namely it had to be close to 125 GeV. If it was a little more or less than that value, the three couplings would not converge at a single mass scale. There would have to be something more complicated going on at intermediate masses. Guess what? That's the mass of the Higgs boson that was discovered! Nobody except those few theorists even put that out there, and they certainly didn't prove it. So, we learned something fundamentally new about Mother Nature in learning, not just that there's a Higgs boson, but its mass is 125 GeV.
We still don't know whether the Higgs is part of a multiplet of Higgs particles. And we still haven't found supersymmetry, which was predicted by that same simple phenomenology to exist at some mass scale that's not too far beyond what has been reached at LHC. Indeed, the gradually increasing reach of LHC has so far failed to find any signals of new gauge fields beyond the Higgs.
So there's adventure to be had in this game. There was an adventure for the SSC that was of fundamental value. That part was realized at the LHC. There is further adventure to sort out either what form supersymmetry takes or if supersymmetry turns out to be not what Mother Nature has in the deck of cards, what is there? Because there does need to be something at some intermediate mass scale. The very painful sort of logarithmic dilemma is that we don't know what scale. And theorists work on logarithmic scales, up to Planck mass, which is completely beyond the what we could hope to reach with experiments.
So that brings us, in a way, up to the present day. And, in some sense, after devoting 20 years of my life to trying to develop viable ways of making very high-field superconducting magnets, I've come to a conclusion that I came to about five years ago, and that is that it's the wrong direction. I believe that we need to ask afresh how can we make a much larger circumference collider, much larger, in an affordable way, and use a cost-minimum superconducting magnet technology to make a collider in it, or possibly even just a single racetrack for proton-antiproton colliding? And reach not to 100 TeV, as the Europeans are trying to make a case for in the present day with their Future Circular Collider, FCC, but 500 TeV! Think of 500 TeV, in the context of LHC, which is 14 TeV. A possible way to do that came to me as I looked at the LHC magnet, in its cryostat in the tunnel at CERN, and mulled over the trade-offs of tunnel circumference and magnetic field strength. And I realized that the LHC magnet is installed in a cryostat, which is a cylindrical pipe about a meter in diameter that provides thermal isolation of the superconducting magnet so that it can be operated at liquid helium temperature. Then I asked what is the average mass density of the magnet in its cryostat? The answer is interesting: 1 gram per cc, the same density as water! So if you put an LHC magnet in its cryostat into the sea, it would not sink, and it would not float. It would be in a state of close to neutral buoyancy. Now, that's just a kind of an odd circumstance, but it led me to start imagining that perhaps we don't need a tunnel at all. Suppose we just connect all the magnets to make a circular pipeline that is neutral-buoyant in the sea, and we maintain it in a state of neutral buoyancy at a depth of about 100 meters, and we make such a ring that effectively inscribes the Gulf of Mexico – a circle of ~2000 km circumference. I then began looking into whether it might be feasible to control its position and its geodesy to the level that's required for long-lived circulating beams in a hadron collider. It turns out that present-day marine technology could provide the control of position and geodesy. There are devices called marine thrusters that are used to steer and control freighters and cruise ships – they precisely maneuver those massive, enormous vessels as it comes into a harbor and approaches a dock. The marine thruster is just a simple propeller with an electric motor on it. It's mounted on a rotational stem. You can turn it 360? to provide intimate control to position the ship exactly where you want it.
Then I consider the separate technical question, what is the choice of magnetic field strength for a superconducting dipole for which the cost of a hadron collider is minimum per TeVof beam energy—not dollars per tesla, but dollars per TeV. The answer is in the range between 3 and 4 tesla. It's not the 8 Tesla of LHC, it's not the 16 Tesla that is proposed for the Europeans’ dream of a Future Hadron Collider (FCC) capable of 100 TeV. For FCC the tunnel would have to squeeze between the Alps and the Jura mountains, go around the Salève, go under Lake Geneva and the Rhône River. And that constrains the tunnel circumference to 100 kilometers maximum, and so would require 16 Tesla for the magnetic field of the magnets. No one has yet built a single collider magnet with that much field strength. And it's not casting a stone at the technologists, I've been unable to do it either, after 20 years of devoting my life to that goal.
Instead my Collider in the Sea would use 4 Tesla magnets (cheap, easy to fabricate), a circular pipeline in the sea (just like pipelines that are built for oil and water) and produce 500 TeV colliding beams. I have been looking at other aspects of its accelerator physics and those have happy answers. High-energy protons emit synchrotron radiation as they travel in their circular orbit in the collider. The 250 TeV beams circulating in the Collider-in-the-Sea would radiate a relatively benign synchrotron radiation power that could be cooled realistically by the refrigerators that keep the magnets cold. The synchrotron radiation would actually damp the amplitude of oscillations within the beams in this situation, so that the brightness for collisions would actually increase for a period of hours after you began collisions with each fresh filling of beams. At this preliminary stage, the C-in-the-S appears to pass many of the accelerator physics and technology santy-checks that could pose a yellow flag or a red flag. So, I proposed the five years ago in a talk at the International Particle Accelerator Conference. They did not laugh, as they had laughed when I proposed pbar-p colliding beams at Fermilab, but the typical reaction was, "Well, that's not really the way we build colliders." Which is what they also said at Fermilab. And it remains that way. It's not taken seriously by the rank and file of accelerator builders and, for the reasons we discussed, high-energy physicists by and large are not willing to even open their minds to contemplate what the research frontier would be at 500 TeV because they see a phalanx of accelerator builders not taking it seriously. So once again I am in the same situation where I have been before... It doesn't bother me.
Indeed, I have just put a new twist to the design of the 4 Tesla magnets that I'm rather pleased about, in which there may be a way to make its magnets not out of niobium titanium, which must be cooled with liquid helium (4 degrees Kelvin), but with REBCO, one of the new high-temperature superconductors that can be cooled with liquid hydrogen (30 degrees Kelvin). The new design hinges critically on managing to deal with a couple of nuanced properties of the superconductor itself. REBCO can only be fabricated in a thin tape, about 1 cm wide and 1 km long. One such tape can carry 1000 Amps of current in a magnet winding, but that performance depends critically upon the orientation of the magnetic field that penetrates the face of the tape. If the magnetic field is oriented parallel to the tape surface, it can carry 1000 A. But if it is oriented perpendicular to the surface, it can only carry 300 A. That is a crucial issue, because the field direction curves over the region of the superconducting winding, and the tape costs a fortune $100 for each meter of tape (tens of $billions for the tape for the magnets of C-in-the-S). I have devised a magnetic design in which the winding is shaped so that the field is parallel to the tape face everywhere in the magnet – I call it a conformal winding. No one has ever built a dipole that way, and in a talk that I just gave at another international conference the experts are chuckling that my idea won’t work. I'm wrestling with those ideas now and seeking funding to build and test a first model.
The C-in-the-S idea comes at a timely moment: the US high-energy physics community is readying itself to do a next Snowmass workshop to develop themes that will go onto the agenda of that for consideration.
Peter, the other "so what" question about the death of the SSC—the first one was a scientific so what, the theorists saying, so what, we knew that the Higgs boson was going to be there. And I think your answer to that pretty well covers it. But there's also the geopolitical question about the larger significance of the United States ceding leadership in high-energy physics. And there the "so what" is, so what, CERN did all of these things, or did all of many of the things that the SSC would've done. So what? Let's think about what might be happening in China which, over the course of the 21st century, might have the greater appetite, budget, and ability to do things at higher energies that the United States in a declining century might never be able to do, right? Or the ILC, perhaps the "so what" is maybe the future in high-energy physics is not to think about these in nationalist terms, but as collaborative endeavors that have to be sited somewhere geographically but might be most fruitful to pursue as an international collaboration. What's the "so what" to answer in terms of the significance of the United States ceding its leadership in high-energy physics long term?
If by "ceding leadership" you mean where a physical machine is built—
I mean politically. I mean calling the shots, setting the tone, deciding what happens, being at the vanguard of discovering new physics.
I think the nationalism is misplaced in that respect. We should be articulating visions for how to do new things and for what to do in the science that makes best use of new facilities. US scientists have exerted that kind of leadership at LHC in doing its physics research. That stemmed from the fact that the US teams are drawing largely from the cast of characters who cut their teeth on the CDF and DZero experiments at the Tevatron. They are the people who, as it became time to design and build the CMS and ATLAS detectors for LHC, had the seasoned experience at the extraordinarily difficult aspects of doing collider experiments at the multi-TeV regime. You have to design the detector and data structure, and everything about what you are recording about events, to do this insane filtration down from billions of events per second of collision events happening where you're recording thousands of events per second on tape, and do it without losing any of the exciting kinds of events you're hoping to see, without cutting them out in the decision process. But also, while including in what you record on tape a pre-scaled sample of a myriad of collision processes that set the context for the exciting events so that you will be able to accurately and knowledgeably separate a true golden event from one that's just a fake overlay of two or three or five uninteresting standard model processes.
A perfect example of what happens when you're not doing that right is what happened with Carlo Rubbia after he won the Nobel for the discovery of the W and Z he was determined that he should be able to discover the top quark in its decay to a W boson and b (the anti-quark of a beauty quark b). His logic went as follows: If the top quark is heavier than the W boson plus the b quark (80 GeV for the W plus another 5 GeV for the b), then a dominant decay mode for the top quark would be into W plus b. Classic argument, it's just the primary weak coupling, a high-mass version of beta decay. Motivated by that vision, in the experiment UA1 Rubbia basically did a premature job of setting up his own express line data analysis in his own collaboration. It was his experiment after all. He structured a set of cuts that were designed to find events of that conjecture, and he was driven by the hope that it might get him a second Nobel for a top quark. Marvelous if Mother Nature had dealt that card. Rubbia tuned his cuts to construct an ensemble of data that had a nice mass bump in it, but the bump was an artifact generated by the cuts. The whole episode was immensely embarrassing to CERN and to the UA1 team. As we know from later history the CDF and D0 teams ultimately found the top at 175 GeV, and it was a very different story.
The ‘non-top’ fiasco was an example of what happens when sufficient care is not taken to understand all of the processes happening in high-energy collisions and to use that understanding to guide the search for new, rare processes at ultra-high energy. The CDF and DZero teams devoted huge effort to build that understanding, and today CMS and ATLAS are doing the same, to develop a data-driven model of every one of the many processes that are going on in their collisions so that they can then design cuts that are not going to produce artifacts as they try to extend the mass reach for new gauge fields. That's the ultimate answer to the question that you asked. Your loyalty is to the physics. It's not to the US or Europe or Asia or anywhere else. It's to the physics and trying to find the most effective way to discover new science and make it work. So where the engine that you need to use is, you pack your bags and you go there if you can find a way. You could say I didn't go. Well, somehow my personal style doesn't really fit the culture of those mega-collaborations who are doing that, and that's no reflection on them. They're doing a splendid job. CDF and DZero were splendid collaborations. CMS and ATLAS are splendid collaborations. They're running those engines of discovery to the best that they can be run to find new gauge fields if they're there. It's just that beyond the Higgs, there really hasn't been something there yet within their reach.
You think there is something there beyond the Higgs, though? You believe that?
I don't know. No. I do not believe that. I think the odds are very good if you just open a wide enough window of mass reach for the search. Hence my Collider-in-the-Sea.
Look for inspiration to our brothers in astronomy. They have said over and over again that, if they build a telescope that enables them to image in a new part of the electromagnetic spectrum, or if they build a telescope that can farther away, they will find utterly unexpected things that will knock your socks off. And time after time, they have done it!
You know what? They're doing it multiple times a year now. And my hat's totally off to them. And the ultimate thing that makes us green with envy is they make such beautiful pictures that bring those new discoveries alive.
By contrast, alas, show me an image of the Higgs boson that you can understand. So, we don't have that wonderful good fortune in our game. We have to do the best with what we do have. So the question of where one builds a machine is a very secondary question. The question of how one builds it, the technical basis of it, makes or breaks whether it ever gets built and whether it works if it does get built.
Peter, for the last part of our conversation, I want to return to where we began with your current research. But, in the interim, we haven't really talked much about your career as a teacher to undergraduates or as a mentor to graduate students. So I want to talk a little bit about sort of your career, not sort of fighting the good fight in terms of all of these panels and the governments and collaborations, but more rooted in terms of your work at the university. So, as a starting point, what have been your most enjoyable courses to teach undergraduates? What's the most fun for you in the classroom to a group of undergraduates, particularly those who you know might never think about physics in a sustained way after your course?
I would highlight three courses. I've taught practically every course in our undergraduate curriculum and most of the courses in our graduate curriculum, and I enjoy that. Some faculty come and they lock into a course that they master, they develop their lecture materials, et cetera, and then it's like a comfortable pair of shoes, they put them on every class day and go in and give the lecture and then focus their psychic energies on their research. I enjoy teaching, and I enjoy the challenge of what I learn from developing and teaching [??]. The three courses that I have found the most pleasure in our undergraduate curriculum in teaching, one of them is a course that is for elementary and high school teacher trainees. It is very close to nonmathematical physics. It's a contradiction in terms, but it's a math light, one-semester course that covers a sequence of topics, is the way I chose to do it, in physics, and couples with each of those topics a hands-on physics experiment that they build with their hands; they leave at the end of the semester with in a box to take with them. And teaching those teachers is just an utter pleasure and delight for me. It's interesting. Just the other day, I ran into a fellow who—who was that, Becky [sp]?
Ah. One of my wife's physicians said to me that his wife, who spent pretty much a career as an elementary school teacher of science, had had me for that course and really loved it. That meant a lot. And I've had that feedback from others, as well, so I just totally love that course. And the two other courses that I—there's a third one maybe a little behind them, but two others that I particularly love are the advanced mechanics course and the electromagnetics sequence in the undergraduate curriculum for physics majors. In those two courses—in freshman physics, you teach students tools of Newtonian mechanics and just the very rudiments of electricity and magnetism that equip them to be able to understand and do problems they have no interest at all. So, at the end of the year, they've learned how to do those things, they are trivial kinds of problems, they interesting in what's happening in our world today, and you just don't feel almost embarrassed spending a year of their time leaving them with that precursor kind of state of things, especially because most of the students we teach that way, of course, never see any more physics. That remains, in my opinion, an unanswered strategic question for physics education. I believe freshman physics is something that we do very badly, all of us practically, coast to coast. Those who try to make it fancier or sexier or whatever end up going down one of several other ratholes so that its impact is not greater, even though it is maybe unanswered strategic dilemma. But when you get to- for whatever combination of reasons decide they want to be a physics major, one of the next things they hit is advanced mechanics. That's where we teach them this amazing thing called the Lagrangian. which seems like it comes out of nowhere. It's like this construct of mathematical terms and mechanics and kinematics that you can't see any motivation for, why did you put this together that way?
And then you teach them how, using that trick, that Lagrangian, you can solve problems you can't even set up legitimately using Newtonian mechanics, and solve them. And then you can prove that the solution is correct. After you've shown them about four or five of those, you can see the puzzlement, the mystification on their faces, the frank disbelief, and then the aha moments where they realize, damn, now I'm going to try to understand why we're doing this. Then you teach them some of the whys, which are sophisticated, they're subtle. And you can watch their brains become alive as a physicist for the first time. And it's like the dawn of a day. In the same with electrodynamics, we teach them the techniques of boundary value problems in that first advanced electrodynamics course, both in electricity and in magnetism, and how, by the very nature of second order of partial differential equations as being the fabric with which all of the language of physics speaks, the intrinsic, every second order of PDE is that it has two families of solutions because it's second order. And almost all problems, one family of solutions is well defined in the inside of a problem and goes wild on the outside, and the other family of problems is well behaved in the outer universe beyond some boundary and goes to hell at the origin. And if you just come to realize that, and that you have a number of different, in mathematical language, orthogonal basis sets of such solutions, two families of solutions, you can chose your two families of solutions appropriate to the topology of any given problem you're trying to solve, and use it to advantage to, term by term, construct an exact solution that may require that you make an infinite series sum of solutions that embody the multiplicity of different terms within each of those families. Bringing them alive in that shows them—and you can again see the dawn come to them—that they can tackle any problem in electrodynamics in that way and solve it and prove that they've solved it. It's immensely empowering. The two things together set them up for how they then play in quantum mechanics to the same PDE theory, the same purpose, and super strength to the same purpose. They're the fundamental notes that keep ringing in this beautiful fabric of physics. I love teaching it.
You probably realize this from your own tenure. If you compare teaching at a place like Harvard to a place like where you are in Texas, it would seem to me that the range of aptitude that you experience at a place like Texas A&M is far more complex and broad than teaching at a place like Harvard. You must have students that, for whatever reason, are just as talented and could go to a place like Harvard but they decide to stay close to home. And then you probably have students that are much more limited in their abilities. And so I wonder, what might be some of the challenges or opportunities in teaching that broader range of aptitudes that you would encounter at a class in Texas?
I think it's enriching because, if you take it as a challenge, it will motivate you to strive to develop methods and paradigms and metaphors that are accessible to students who are more poorly prepared, and ways of layering what you're presenting that will not bore the student who is well prepared, and will also not lose a student who is poorly prepared, as long as they're both engaging. The deeper challenge at Texas A&M, I have to say, is that, again, from my experience and my observation, fully a third of the students that are admitted here come with no serious notion of what they're coming for, of what a higher education means. There are, indeed, some students of that sort at a place like Harvard, and I taught at Harvard for five years. So it's very tricky.
The best of the students at Texas A&M that I have had the pleasure to deal with over the years are fully on a par with the best of the students that I taught in my brief time at Harvard. The weakest ones are certainly weaker than the weakest of the ones that I dealt with at Harvard, so there's a wider spectrum, which is what you said. They're both challenging environments, challenging the middle road students to make them the best they can be is the biggest challenge, in my opinion. I don't neglect the weakest students, but I tend to focus on the middle to try to pull them up [unintelligible] and [unintelligible] with what they can do if they just work hard. But the question has another side to it that actually participating in research, and that has been a great pleasure to me through my career.
Through most of my career, I managed to sustain the kind of intellectual family that you want to have in doing research, namely a family that starts with postdocs that are with you who are expert in the tools of what you're doing, et cetera, graduate students that span from those who are now approaching their dissertation work and they're well versed in what they're doing and they're trying to use those techniques to make those measurements that they've been working hard to prepare themselves for. The entering graduate students are trying to figure out what the hell's going on in this game of research. And then the undergraduates who are fresh to any notion of research and their understanding of just basic physics mastery is very spotty and has high and low points all over the place because they haven't had their full curriculum of courses yet. If you have the good fortune to build and maintain people with each of those kinds of four categoric kind of aspects to them at any given slice in time in your group, it works to everyone's glorious benefit. Because, wherever a given person is on the peg in this structure, there are multiple levels of expertise above them and all except the lowest one has people below that they can—with the fresh humility they have from having to try to learn from the next pegs above them, they can try to be patient and conscientious in teaching the new kid that's just showing up or the one that's first trying to learn what's going on.
And I've managed to keep that family dynamic going for at least 30 of the 40 years that I've been teaching. I'm sad to say that it kind of fell apart circumstantially over the past two years so that, almost without my realizing what was happening, I lost two marvelous, very seasoned graduate students, one a year after he spent a year with me as a postdoc after graduating, then a third one all within the progression of one year leaving me with one graduate student who was—needed a lot more nurturing, and the only people he could get it from was me and the postdoc. And then, my postdoc took a job with one of the two private companies who are bravely setting out to build a 20 tesla Tokamak fusion. So, at the present moment, my team consists of myself, the two graduate students I introduced you to, one of them has been with me for one year and I'm happy to say he is maturing rapidly, but he has no upper reference, you see, to learn except me. And one undergraduate who's very good in his learning, and then the other graduate student, this summer is his first time here. So the family dynamic is, unfortunately, badly depleted, but I'm happy to say it's depleted but not broken. And spirits are good and I'm confident with good luck over the next year or two, I can rebuild it to the kind of multitier that I had before. We'll see.
Peter, what have been some of the characteristics that your most successful graduate students have shared over the years?
They're able to land on their feet and learn a new box of delights in a new job. And several of them have done it successfully over and over again. One of my recent graduates went from here to PSI, the Paul Scherrer Institute in Switzerland, and you could almost without exaggeration say he revolutionized their understanding of their 30-year-old Synchrocyclotron, which is the highest energy machine for that whole area of nuclear research in the world. He then went to the Lawrence Livermore Laboratory where he is leading the construction of an electron beam project making it a very, very high current electron beam using linear induction modules. Totally different domain of kind of accelerator from anything that he had experience with with me. And he's their top guy in that. And Livermore is the place where induction machines were invented 40 years ago, 50 years ago. So he has landed on his feet over and over again very successfully. Picking another one—and several of my students who have had challenging dimensions of where they go next in their careers have been driven by the family decisions associated with their wife's dual career, which is another subject that's of very great importance in this day and very unappreciated.
I'll get there, dear. My wife's listening in on all this.
I'm glad, and I'm sure she has great input. I welcome it.
My student's wife is a successful environmental biologist and got a very good job in the triangle in North Carolina. When she got that job, he had simultaneously gotten a job at the company who makes the best superconducting wire in the world, going into the industrial side of making superconducting wire. He became very valuable to them, but he was also in [unintelligible] and she was in North Carolina with his two children. So he sought and landed a job in North Carolina, and that ended up being with a company who make very efficient LED lighting for home and commerce. What is the name again? Company? [unintelligible] and buy his light bulbs on the shelf there free. And he has become a senior of—this is just in three years of employment for him—he has become a senior member of their skunkworks team who are developing better LED lightbulbs with better ability to cover spectrum, to tune the light color you really want to have it, et cetera, and the high intensity for commercial and industrial applications, et cetera, et cetera. So these are people who land on their feet and become productive like that in a challenging new regime. One of my undergraduates left here after [unintelligible] in our magnet development R&D and took a job with Boeing in their skunkworks out in Seattle. He took that job just at the time that they were having a new problem with exploding batteries. You may recall that episode—
—in the era of their planes. And [unintelligible] in and developed an understanding of why the batteries were exploding and what they could do to eliminate the problem. He then went on to graduate study in physics on their payroll at Berkeley and is doing very well in the present day. Another left me, again, out of an undergraduate thesis experiment, went to Berkeley, and went to work with Clarke, who is the fellow there in their physics department who has pioneered zero-field and ultra-low-field MRI, magnetic resonance imaging. In the usual way you think about an MRI, you think, oh, you need a 1-1/2 tesla magnet or a 3-tesla magnet or, for functional brain imaging, 4 tesla or 6 tesla or whatever you can afford. He showed how you can get some remarkably powerful information in the absence of magnetic field. It's just beautiful and very, very clever, and it works. So, the world is the onion to this guy. So they're doing great things. So those [unintelligible]. The only other [unintelligible] believe that could account as 30 graduate students, they populate mostly national level labs and a handful of universities. I've had several women students who are very successful. One of them is a professor now doing nuclear materials in the department of physics at UT San Antonio, very successful in developing new materials to try to mitigate the ills of conventional power reactors in which their cladding is attacked by steam in the event they lose cooling and that's what leads to meltdowns. So, hypothetically, if you could imagine a magic cladding that could survive high-temperature live steam, you would, if not eliminate the possibility, at least dramatically reduce the dimensions of what would happen in a meltdown such as happened with Fukushima and Three Mile Island. So, she's very good. [Unintelligible] graduate students is now a staff member at Fermilab where she's a part of the team that are building the next generation muon g-2 experiment that is kind of like—you may recall at the very beginning of our whole discussion last time, that's the second of the five generations of that that happened at CERN is the one that I went to CERN and gave first thoughts to joining but decided instead to go work with Carlo. So those are some examples.
Peter, just to bring it back to the very beginning of our conversation when you gave me that fantastic tour of your lab, another theme obviously is that, for you and your graduate students, fun is part of the equation. You love what you do. It's fun to do what you do.
Absolutely. Absolutely. Without the fun I don't think I could do it. I spent a long period in this pursuit of high-fuel superconducting magnets. It was not without its fruits. We are now in the finalist consideration for being funded by an entity called RAP developed to use this tape conductor I made mention of in connection with my collider in the sea at the other end of the low-field versus high-field domain, namely to address the challenge that they pose to make a 20 Kelvin toray that would open the parameter window for potentially taking fusion into what it would require to make net electric power at a commercially interesting level. And doing that required us to use literally all of the tools. It was very gratifying in that, what we came up with, which uniquely enables that shortly phrased but almost impossible thing to undertake for a toray, uniquely uses every one of the tools that I spent 20 years developing for very high field dipole magnets for hadron colliders. So the bottom line is my own conclusion is that they are really not the right answer for hadron colliders of the future, but they well may be the right answer for maybe making fusion possible in the future. Many challenges to get there. That particular challenge is one that may be working.
Peter, for the last portion of our talk, I want to ask a few broadly retrospective career questions, and then a few questions that are sort of more forward looking. So, first, do you see one particular scientific discovery that you've been involved in as standing apart from all the others in terms of your contributions to the field?
Certainly, the one I believe has the most significance in that way is putting the pieces together to make a viable concept for doing proton antiproton colliding beams and thereby making it possible to discover the weak bosons. That opened, among other things, a development of what [unintelligible] of beam cooling and realizing what beam cooling can do to enable the use of accelerators for all sorts of things. And, indeed, the proliferation of synchrotron [unintelligible] radiation facilities uses that as its workhorse, its fundamental engine of making [unintelligible] beams for discovery in every field of science, literally every field of science. But that small role that I had in bringing a broader realization of beam cooling and what it does to move us out of slavery to Liouville's theorem of conserved phase space and how to then use it systematically to best purpose I consider as the thing in a way I'm most proud of.
What have been some of the biggest things that you've learned on, I guess, a sociological level with all of your involvement in high-energy physics, in terms of dealing with people and the best approach to getting to what you see as the most effective solutions?
I do not have strong people skills. I never have. I am occasionally very successful in the arena of persuading people, motivating people, et cetera, but I do it best in a one-on-one way. The dynamic of management and leadership in the scientific community and the technological community I have found to be very limiting to me, and to be very challenging for me to find a way to work within. I am not an organization person and I find it very difficult to discipline myself to tune my way of speaking, my way of articulating ideas, my way of responding to people in a fashion to optimize the results I get out of a situation. It is a weakness that I have, in some sense. In some sense, I think that weakness may couple to some of my strengths, so that if I were stronger in those respects I would be weaker in others, so I don't necessarily regret that I have that weakness, but I'm self-aware that I have it. But I don't know that I have learned pieces of wisdom about the sociology of science and of the sort of organizational process of the doing of science and national laboratories and government agencies, et cetera. When I need to, I do my best and am occasionally successful in finding a way within whatever is their ordained modes of judgment to get the backing to do something I want to do. I'm not more broadly knowledgeable or skilled at what you might call the sociology of the process or the dynamic of those entities.
If there was a through line that might connect what you are willing to subject your body to to not go to Vietnam and to demanding to see Panofsky that you should be led into that meeting—
—what do you think that is? Do you see yourself as an iconoclast?
I have ideals and values, in the case of Vietnam, ethics, that I will not compromise. I understand that there must be organization and decision processes for this world to work as a society. I get that. Having gotten it, I am not averse to finding my way in the best I know how to achieve my ideals, be consistent with my ethics, to make new science happen that stretches and bends and, if necessary, challenges that kind of decision-making and management structure that society must have, both in science and in general.
And, in terms of looking forward, Peter, we've certainly talked a great deal about what was lost with SSC. What do you think the physics community, the high-energy physics community broadly—not just in the United States, but, as you mentioned, that it's really irrelevant to think in terms of nationalism—in what ways have these experiences from a broader perspective of just the '80s or the '90s, in what way might the high-energy physics community as an international collaboration might have learned from this experience to produce compelling and important science in the decades to come?
It's very tough. See, we're in a very tricky time. In the '80s we had mileposts that, in effect, we could use as guidance in structuring our thinking about what to perhaps try to be fortunate enough to build and make happen next. We had the very compelling prediction by my friends, Glashow and Weinberg, of the weak bosons, and just where to go look for those Easter eggs. We just needed to cleverly come up with an affordable way to do it. In the case of the Higgs, the milepost was fuzzier. We couldn't give [unintelligible] an upper limit to a mass scale with TeV by which, if the Higgs evidenced as a particle, it was simply not Mother Nature's choice of how the world, the universe was organized. But, in those two cases, we had fundamental guidance. In the present day, we don't have that guidance. We don't have a milepost. And what I see the world doing is groping for—you might call it a lesser milepost that is tangible and is, in principle, achievable. And use—and there are two of them, actually—and to seize upon those the rationale for building the next-generation facilities.
But one of those two mileposts is what you might call a Higgs factory. That's what the [unintelligible] with their—I don't know if you've read up on the ESS, the European Particle Physics Strategy. Yes. They just came out with this a month ago or whatever. It's an articulation or a validation of a progression of thinking that's gone on for about five years now in which [unintelligible] there are potentially two things they could do in a [unintelligible] circumference tunnel, which is the largest tunnel they can possibly put in the Rhône Valley of Geneva. One of those is a circular hadron collider that I made mention of. That one they see something that is far off in the distant vision that they may not live long enough to see mature and the technical capability to do it, but it's a worthy vision, as they see it, to look toward. The other is a Higgs factory, which would be a circular electron-positron collider—circular meaning two rings of low that are relatively low-field magnets that are circulating beams of electrons and positrons strong radiation and colliding them at the Higgs vertex. So it's a fixed energy collider. It sits on the Higgs and it just makes billions of Higgs a year and records them on tape and detectors. The purpose that you potentially can achieve with that is to study intimately all of the coupling of the Higgs to the other gauge particles, the structure of those gauge couplings, the quantum mechanical phases of the gauge couplings, et cetera, to really map out the Higgs as an intimately connected new part of the standard model. Now, that is a very worthy thing to do, potentially.
And the key here is to make precision measurements of those, not to discover a new coupling. It is to make precision measurements of couplings of the Higgs to all of the other particles in nature. Through those couplings, the coupling leads to, let's say, the top quark, it's not just one coupling, it's a whole bestiary of what we call Feynman diagrams, each of which is a constituent of the real process but it's the coherent sum of all of those contributions that is the visible process. That's how quantum mechanics describes such a thing, such an interaction. The power for looking in a prescient way toward the broader scope of Mother Nature is that there can be terms in that summation of diagrams that involve particles that we can't find, that are beyond our reach, our energy reach, but there are virtual diagrams where they appear momentarily in the language of quantum mechanics very briefly, coupled to a real particle and then are reabsorbed. And, by doing so, they give rise to a measurable property of the interaction between particles. That's called virtual diagram physics. So, in that virtual diagram physics applied at the Higgs vertex at the colliding make a few numbers with Higgs lies the potential to [unintelligible] what we can say about a regime of mass scale that's a factor of 10 beyond LHC, then may be a factor of 20 beyond LHC, without building a machine capable of reaching that much higher energies. So that is the theme that's been seized upon by the Europeans in their new strategy.
The second embodiment that it could make—and there's a lively, healthy competition in Europe and also Japan toward that same goal—there's another team at CERN that goes by the acronym CLIC who would propose to do the same thing with a Linac collider, two linear accelerators colliding electrons and positron applying [unintelligible] them at the Higgs vertex of mass scale to produce billions of Higgs per year. The Japanese are proposing the same to take a leading role in doing it. So those are three examples of a next future machine that would be focused on this particular vision of the Higgs—the virtual physics one can do at the Higgs [unintelligible]. I apologize for the jargon. It's kind of tedious probably.
There is a second theme, and it has become the primary focus of the US high-energy program of today in parallel with continuing support of those very successful US teams that are on LHC continuing that physics into its new run with [unintelligible]. And that has to do with another virtual diagram process, in fact, having to do with neutrinos. The neutrino is a nearly [unintelligible] cousin of the electron and he has a weak muon, and another one, the tau. So each of those charged leptons, weakly-interacting charged particles, has an electrically neutral brother or cousin, its neutrino. So there is an electron neutrino, a muon neutrino, and a tau neutrino. It sort of [unintelligible] with those three flavors of charged lepton. Long ago and early in the days of the LEP electron positron collider at CERN back in the early '80s or the late '70s, the measurement of the display that the LEP collider was a Z factory that made electron positron collisions sitting on the [unintelligible], on the mass 90 GeV of the Z boson. The Z is the neutral weak vector boson, it decays into most—pretty much all of its dominant decays are into pairs, particle-antiparticle pairs of fermions. So it decays into pairs of quarks, like up up bar, down down bar, up top bar—that one doesn't have one 'cause it's too heavy—B-Bbar, and also into the electrons, E+/E-, U+/U-, tau +/tau -. But the first order with equal amplitude, equal probability of happening [unintelligible] a little bit in a couple [unintelligible] in the masses of the quarks and the leptons in turn, but it's the first [unintelligible] they're all pretty much equal to equal pole probability. But also it can decay with equal probability into neutrino pairs. The electron neutrino and his antiparticle, tau neutrino and his antiparticle, the muon neutrino and his antiparticle, et cetera.
So this particular experiment at LEP was extremely elegant and extremely powerful in what it could tell us. It simply measured the width of the Z boson as you could measure that width in any of those decay channels. Width meaning if you change the exact collision energy of the electron and positron that are making the Z, you make it a little lower than the Z mass, the nominal Z mass a little higher, it's not a case where the energy has to be exactly that value, the GeV that is the Z mass, it can be 89.8 or 90.1 . I'm just pulling numbers out of my hat. The width of that, plotting it out as a Lorentzian by taking the large quantities of data, through the simple language of quantum mechanics you can teach in the first course in quantum mechanics a student learns, the width is proportional to the sum of all of the decay channels. The more decay channels there are, the wider is the width. So, by precisely measuring the width of the Z boson, we came up with a profound result. There was only room for exactly three species of neutrinos. Now, why is a neutrino specifically magic in this way? All of the charged particle fundamental particles have mass. And if you go from the down quark to the up quark, the charm quark to the D quark to the T quark, the mass gets bigger with each one in turn as you go up the multiples. Same with the leptons. The electron has a half an MeV of mass, the muon has 100 MeV of mass, the top quark has 2 GeV of mass.
So if there were another species—now, you could ask the question, why are there only three families of the fundamental particle? Three families of leptons, three families of quarks. There's no good answer for that. If you can find one, I'll be happy to nominate you for the Nobel. So it's a perfectly reasonable conjecture to say, suppose there's a fourth generation. And, indeed, whole particle colliders have been built hoping to find the fourth generation. None has been found. But this pivotal experiment of measuring the Z width gave us the result that there was only room for three families of neutrinos in that sum count, otherwise it would've been wider. Now, the lightest neutrino has almost no mass at all. The next neutrino has almost no mass but a little bit. The third one has almost no mass but a little more. They are all so ridiculously small masses, EV scales of masses, that, if there were a fourth generation, it also would also have EV scales of masses. So what that tells you is there is no mass barrier, no mass energy barrier, to creating a putative fourth generation of neutrinos in Z decays, 90 GeV, if one was there. It would be really unthinkable that there'd be three generations of neutrinos and then a fourth that's, in all other ways, a cousin right along with his three cousins, and yet he has a mass of 100 GeV. Get real. So what this did was to terminate that number of species that there are, that number of families to three. Can't be four. That one pivotal experiment proved for all time that fourth generation of fermion. So, for some of us, that kind of limited our enthusiasm for neutrino physics as something that was exciting to go try to push harder to understand better. For others, it just whetted their appetite. It just shows there's room in the world for both. I mean, I started my career—when I went from my postdoc at CERN, I came to Fermilab to Harvard—you may recall that I said I came there to be Rubbia's anchor on the neutrino scattering experiment.
Which, at that time, was one of the various ways that you could see indirect evidence of charm through the [unintelligible] plus [unintelligible] minus decays, and the cascade decays of the D mesons that were produced by neutrino interaction. Well, in the intervening years since then, a very interesting aspect of [unintelligible] has become ever more well understood, and that is neutrino oscillations. And, by those oscillations, what it means is that the three breeds of neutrinos associated with the three breeds of charged fermion, charged lepton, are not quite exact eigenstates in the language of quantum mechanics in their decays or their interactions. They don't quite interact purely as an electron neutrino or as a muon neutrino or as a tau neutrino, but slightly as add [unintelligible] mixtures, and the add mixtures evolve with time, after the eigenstate is produced, because there's a slight mass to each of those three neutrino. So there's what's called a mass matrix to them. And they're tiny masses but they're not zero. And so, if you put a number to it, for the [unintelligible] Fermilab, by the time neutrinos are made on a target and traverse the length of a long lever arm of transport still onsite at Fermilab, you do an experiment at the end of that line, you can see clear quantitative evidence that the neutrinos that are interacting are not only electron neutrinos, if that's what you've tuned the line to make, but also muon neutrinos, et cetera. And if you run that—either you run the length of the arm out, which is, of course, a very expensive thing, or you look at the interactions of many energies of neutrinos, which by the Lorentz boost of these very tiny mass neutrinos as progressively higher energies, you stretch out the oscillation, one family of neutrinos and the other, in a length scale that's proportional to energy.
So, by measuring [unintelligible] those interactions for neutrinos of different energies, in effect you can map what's going on as you go through an oscillation from one pure type that you made a target from decays of pions or kaons or whatever process you choose to the ones that are then interacting in a charged current interaction or a neutral current interaction in your detector. That very nuanced thing of neutrino oscillations has become virtually an industry in the world of neutrino physics because it gives us the ability to probe through these same virtual diagrams the origins of what's making the oscillations happen. And that involves very subtle deep things in the level of the mass matrix of the neutrino sector, using the language that those people use, and also involves CP violation, the violation of the combined [unintelligible] of symmetry operations, charged conjugation, and parity version that have lead to three Nobel prizes over the past three generations, and are one of the deepest beyond the standard model parts of our world of particle physics as we see it so far. The origins [unintelligible] CP violation remain mysterious and the subject of more papers practically than there are atoms in your fingernail. It has a very tangible impact on the very nature and fabric of our universe. Our universe consists almost entirely of matter and no antimatter. That is because of CP violation back in the beginning of the Big Bang. That tiny CP angle resulted in a difference in the quantum mechanical amplitudes, the virtual diagrams, which were then not virtual they were real. So that led to the particles being in that phase of the universe having slightly lower mass scale than the antiparticles and through CP violation they were selected out in the sense of [unintelligible] natural selection to the extreme level of one in a billion, so that the natural abundance of antiparticles in our universe today is parallel to that of photons, which is about one in a billion compared to baryon. Sorry. The other way around. So it has profound significance linking back into our understanding of cosmology, how our universe began.
It's a very big picture question, why it has the nature that it has today; very big picture question. Whether studying neutrino oscillations and all the ways people can come up with to try to study it, both from neutrinos from reactors and neutrinos from accelerators, honest men can differ on. I don't yet see myself, speaking as a high-energy physicist, a credible conjectural path by which, from an understanding that might be attainable with ever better neutrino facilities, one could ever, a discerning, branching point in those very important and fundamental things by that particular route of virtual diagram physics. I could be wrong. Although I may sound otherwise, I am humble. I'm not proclaiming that I'm all knowledgeable. But I don't see the case for it. The US—now shifting to the political and scientific politics realm—the US high-energy physics community—I may mistake this, but it's just how I see it—because it cannot see any path it considers credible that the US has any potential to be a home to a future collider that has the potential for something of major consequence, it has seized upon this as being a solid physics mission that it's prepared to focus pretty much the whole very limited bag of chips that the US has that it's willing to devote to high-energy physics to try to push this along. It is the central agenda for Fermilab and its future for its high-energy physics program. There are other virtual diagram experiments like the—and g-2, as well, but this whole package of virtual diagram physics is what Fermilab sees as its vision for the future for its laboratory. I don't knock them in any way. I wish them nothing but well. It doesn't feel compelling to me as worth a candle [?]. And I don't see the significance of the marginal—to my judgment marginal—incremental understanding that each of the billion-dollar-scale experiments, some of them being built now and others proposed, would bring to us in those studies of neutrino interaction. Like I say, I'm a very minority opinion in that. That's just the way I see it.
Peter, last question.
You've given a view from 35,000 feet, but I want to ask specifically, for an individual, time is limited, resources are limited, you have so many students; what do you want to accomplish personally? What do you see as the areas of scientific inquiry that are most fruitful for yourself in terms of what you want to accomplish for the rest of your career?
Well, the rest of my career is becoming a shorter and shorter window of time. There are variations on the theme of the language, but each of us have but so many years that we're going to have on this earth, and none of us, until late in the game, have any real clue how many that number is. It might be 10 or 20 or 40 or 80.
I'll point out that, just for example, Ted Geballe at Stanford is 100 and he's active.
Robert Finkelstein at UCLA is 104 and he's active.
Well, when I was 20 years old, I had a certain urgency to my choice of themes of what I was doing because I was determined that I was going to make a major impact by the age of 30 because I felt it very unlikely I would live longer than that. That seemed the horizon to me. And I managed to pull it off. I was born in 1947, and in 1976 I proposed proton-antiproton colliding beam.
But I have managed to live longer, and, to my great good fortune, I remain in good health. I have given thought—
This despite having almost killed yourself during the draft days?
Well, a number of times, but those were—whatever. The closest I came was in a car wreck at the age of 14 when I was in what was then called the "death seat," the front passenger seat, and my friend who was driving was doing some absolutely crazy thing on Halloween night with the result of having a T-bone collision with another car that threw me through the windshield. So that was probably my closest call. But, going back to my present day, I have, for about five years now, taken very seriously a [unintelligible] written by a colleague at MIT, Nobelist, and the article was actually in the MIT alumni magazine. I forget how I came across it because I don't ordinarily read that, but it was a very interesting article in which he—he was then 65 years old. He got his Nobel, as most who have one do, when he was 45 or so. And the purpose of the article was writing to scientist colleagues his thoughts about tenure and retirement. He said he felt that tenure is a truly unique privilege that the academic world in many places has set to its faculty. The number of places has shrunk, so now the US is just about the only one that carries it to the retirement dimension. Namely, if you have academic tenure, you are immune to being fired for anything short of grievous misconduct or incompetence.
And so the obvious question arises, what is the right time to retire for any given individual as they reach the age that various measuring sticks say is a point when you maybe should hang up your shingle in one fashion or another? And he had reached the assessment that the—so that ethics list and he did a very eloquent job of assessing that matter of ethics. As our healthy lifespan gets longer and longer, the kind of window of time at the front gate where we turn people out with a PhD as a credential to enter the academic world, if that's what their star tells them to do, stays about the same, namely the age of 25 to 30. And so people come into that, they have a limited window of six years by AEEP rules, they're taken in as a tenure-track job, they have to be up or out. And if they are out, they might get a second track at another university, but the odds are much lower, et cetera, and they need to look for another kind of job or another kind of career. He felt that that makes it very poignant for those of us who have academic tenure, as we then get older and older, to simply hold onto it as long as we can shuffle to the blackboard and do our teaching and essentially shuffle in the laboratory and do our research that's sufficiently competent that perhaps people will fund us. He said he had given serious thought to this and, for several years, as he approached 65—which used to be a milestone for such things—and he came to the conclusion that the current milestone, for it to be viewed to be 70-1/2. That's a very specific thing to pluck out of your left ear as to a new milestone, right? And he said it's as close as it makes [unintelligible] to get because he needed to have something that you can articulate as a specific point by no lesser body than the Congress and the Social Security program, which vests to you your full Social Security benefits even if you keep working longer because they view that that's when it's entirely appropriate that you should retire. And that's not the reason, but it at least gives kind of something to tie to externally as a point when, even if you are still vigorous, even if you're still teaching well and you're still doing research well, you should release the tenure for teaching part of your position so that young persons coming into the field can vie for that position because universities can only justify so many faculty salaries, after all.
And so then, if you feel that you're good enough to continue, you've convinced your university to give you emeritus status that maybe lets you keep your office, maybe lets you keep your laboratory, maybe permits you to continue advising graduate students in their research, continue to compete for research grants, and if you get them, to run them in your laboratory, et cetera, but to try to take a view that you're going to make room for another young person to come in again. So I articulated this to my colleagues in our department on the occasion that I declared myself as a candidate for department head and they chose me for that job, which I held for only a year and a half, in a time when we had a certain dean from hell and a very dismal time of affairs within the house for how to cope with some of the realities of things that led me to resign as department head. But, in addressing the faculty, I put this squarely on the table to them as, at least for me personally in my ethical view of it, that I found very persuasive. And I'm [unintelligible] I should make the comment that Vederlin [sp], when he reached the—the fellow who wrote that article—when he reached 70-1/2 released his tenure. And research entity , they hired another person in this related area close to what he does, and he partners with that person, and they're a dynamic duo and doing great things. And he does some of his own, she does some of her own. That's all great. But, in other words, he walks the walk. I have not yet walked the walk. I'm now 72.
My college has articulated a phased retirement option that enables a faculty member to opt to drop to half time being on the faculty for teaching for one semester a year for three years, and then releasing [unintelligible] at the end of the period that, at the end of it, you will fully release as tenure. So they can then count on the release of that tenure slot in their [unintelligible] for new faculty and all the rest of it in an orderly way. So I'm launching that phased retirement clock now. I'm requesting to continue with those things I said, emeritus and to keep my lab. In my case, fortunately, I have a very large, lavish lab space but it's in an industrial building that's about six miles away from campus out in the woods.
No one wants it anyway (laughter).
No one wants it. So I don't know if they'll permit me [unintelligible]. I'm right now framing the question and it will go to the faculty this fall, but I expect that both the university and my department will have no problems, at least for the immediate future, in permitting me to take to rattling around out there as long as I chose to do so. As to what problems I—the measure of any scientist in any field, in my opinion, you could almost say anybody in anything that he does, is his choice of problems that he attacks. That really is a measure of the man or the woman. And I find it equally challenging and satisfying and rewarding to tackle—the things I look at interesting to tackle are all problems that pertain to either superconductivity or accelerators writ large. But the avenues that those two themes cover is a pretty large space, and I find interesting challenges in many, many dimensions of that. The collider in the sea is a challenge that I plan to continue hammering on until and unless I see any reason why there's a barrier that it would cost a prohibitively large amount of money or not work for one or another reason, or that the potential [unintelligible] with 500 TeV of collision energy is not worth a candle.
Another theme that I've taken up just in the last year pertains to magnetic fusion. That's a very big challenge. In many ways, it's as big a challenge today as it was when I was in college and I can still remember swatting up some articles on Lyman Spitzer and his first notions of magnetic field geometries for magnetic and time of fusion. In some sense, it's as elusive a target to [unintelligible] to practical dimensions electric power today as it was then. It's just that we know a lot more now. But at least one of the dimensions of that challenge, the magnetic one, I'm beginning to believe has a credible solution that's end scope in cost and performance to what would be required. So that's one domain of thrust. Another one, in a very different arena, is a variation on the theme of magnetic resonance imaging. I built a whole-body high-field MRI system a long time ago for the most eminent of all customers, Paul Lauterbur, who is the co-discoverer of MR imaging. It was an instance—one of the gratifyingly few instances of having to admit failure in my career. We built the magnet, it worked, but it self-destructed because of a stupid thing that the research team did once we delivered it to the University of Illinois. And, if built properly, it should've been immune to that self-destruction, so I take the stone for that. At any rate, that early bug—that was back in the days of TAC, the Texas Accelerator Center, that we built that while the SSC was being built—that made an itch for me that has persisted ever since. MRI is just an absolutely fascinating and immensely powerful method for diagnostic medicine. And my thinking on it hitched to some personal experiences pertinent to breast cancer in specific because a number of people in my own family and in the families of my graduate students were diagnosed with breast cancer and some of them died, some of them are past the five-year remission. But, in all of the cases that seemed to crash upon my world over a period of about five years, they had one common ingredient. In every case, the woman had had a healthy outcome from a state-of-the-art mammogram—
—less than six months before she was diagnosed with cancer, and beyond first stage, in medium stage or stage two or three in the different cases. Number two, each of them discovered the disease themselves by palpation or by a discolored region on their breast, not by the benefits of modern medicine. So mammography failed those four women, just failed them flat. That stimulated me to learn more about mammography, how it works, and what are its shortcomings. Mammography has a sensitivity, meaning, if a person comes in with early-stage breast cancer, what are the odds that it will be detected, of only about 50%. You'd like that to be near 100%, right? It's only about 50%. That is not made clear to the patients. The patient comes in, oh, yeah, the mammogram's clear, and the patient feels relieved. It's not much better today than it was about eight years ago when I began beating on this idea to try to see what could be done. The problem is that mammography has an intrinsic ability to detect early-phase breast cancer, typically within a given nodule within a totally localized region of the breast and has not made broader damage. The only signal mammography has is the microcalcifications that are formed when the cancer cells kill healthy cells so that the body's own immune system calcifies those—it doesn't see the cancer cells. They cloak themselves. But it does see the corpses of the dead healthy cells and it encapsulates them, as part of the healthy immune process, in calcium. It makes tiny microcalcifications that are smaller than a grain of sand. It makes them in a pattern that then is wherever the dead cells were, and they are there for the rest of the patient's life, those little calcified little bits. Mammography can only detect those tiny, less than a grain of sand, in a shadowgram of mammography, either on film or now in digital detection. But it's an extremely subtle signal to find. There are many, many things that can happen to healthy breast tissue that produce patterns of microcalcification or calcification of healthy regions of tissue that look like these things [unintelligible].
So finding the wheat from the chaff is every bit as challenging as finding a Higgs boson in a CNS. And so it's not surprising that it has that limited success rate. By contrast, MRI has the beautiful mechanism for very sensitive detection of early-stage breast cancer in doing a dye-contrast method, [unintelligible] dynamic in which you image the patient's the patient's breast—both breasts—in MRI. You use a contrast agent that you inject, and the contrast ingredient is a high-nuclear spin element like gadolinium, a spin of [unintelligible], that is chelated with a starch or sugar and then injected into the bloodstream. So if you take an image before injection and get a high-resolution image of the breast, changing nothing you simply inject the dye and, in progressive shots you take every second as this courses through the bloodstream for 3 seconds or a minute, and then much later at 2 minutes and 5 minutes, you take a succession of high-resolution images. And you do an image subtraction of the obvious sort. What shows up are the locations where there is aggressive uptake of sugars and starches. And so what you're seeing are the locations where there are cancer cells which are—their biggest single neon sign signature is they are aggressive. They are taking up sugar and starch to grow, whereas the healthy breast cells, they're there. They're breast cells. They're sitting there doing their thing. They take up very little sugar and starch with time out of the blood.
So, in the hemisubtraction, the cancer cells show up with extreme fidelity. The healthy cells, including benign tumors, benign cysts, all sorts of things that are simply structural features of the breast, and the breast is a very complicated organ within the body. Many kinds of tissue and elaborate structure ducts and nodes, those are then taken away and you see exactly what you're hoping to be able to see, this cancer. That was all perfected long before I began looking at this process. So you may [?] ask, why isn't it used? The answer was simple, dollars and cents. A high-resolution, dye-contrast MRI costs about $1000, a little less now, but it's still a few hundred dollars than a high-quality mammogram costs. And this is something—to make it effective for early detection, which is the only way to save women's lives, you have to do it for healthy patients starting at whatever trigger age you want and do it every year, just like you do mammograms every year. Otherwise, it doesn't matter that it's ultimately sensitive, the cancer will bloom and kill the woman before you find it. So the cost has to be affordable in the budget picture of healthcare. Well, MRI is not affordable in a whole-body imager with the very best technology that people have thrown at it, and they've tried a lot to try to reduce its cost from this point.
The problem is very fundamental. It has nothing to do with the technology of the MRI, at least in a direct way, because the MRI gives all the field quality that you need, the methodology gives all the resolution you need, the picture, so what's missing? What's missing is that it takes a precious hour to set up a patient for whole body imaging, put them into that whole-body imager, run the sequence of images, and take them out and go forward. An hour. The machine costs several million dollars. The floor in the hospital costs a million dollars. Run the numbers. Just that capital cost and that floor space cost, when you can only put patients through one per hour through the working day, that's what sets the cost of MRI imaging for breast cancer and makes it something that they—now, when a cancer is found in early or in advanced stage, cost is no object. Then an HMO or Medicare or whatever will happily fund to have as many high-resolution MRI images as you want to take to show the process of what's happening and what you're going to try to do about it. And of those women, if you catch it after phase two—after it's into phase two, the odds of long-term survival go down from 98% to about 80%. If you catch it late in phase two or phase three, they go down to about 60%. So the budget is wide open to image women as they're dying from this disease, but it's just a budget breaker to use this wonderful methodology to save their lives. Because, to save them, you've got to do it as a well-patient imaging.
That's the preface—what I came up with is a walk-through 1-1/2 tesla MRI system—I can send you a paper on it and you've got a link to it in the bibliography—which costs about the same as a whole-body rig. What it does for you is it couples in with a revolution in the image sequence so that the image sequence itself can be 10 minutes of total turnaround time, actually in 3 minutes. A clinician named Christiane Kuhl in Aachen, Germany did the clinical trials evaluation of a methodology she worked up where she found that, in just that first minute or two of images that you take, you can already make the resolution to find the early-stage cancer definitively with high sensitivity. You only lay a longer train of images to discerningly differentiate between the different forms of cancer that it could be. But those you can come back and do as a follow-up imaging if you find this in screening. The screening you only need 3 minutes in the machine, which means 10 minutes total time from when you're suiting up with the RF-coil [unintelligible] arrangement to the time you're out and another patient is in. So you can reduce the one-hour turnaround time in the machine to 10-minute turnaround. That's the difference in making this accessible and affordable for well-patient imaging. It remains unrealized, undeveloped. I got some seed funding for it. I have not succeeded in getting follow-on funding to carry it into first trials. We have teams at two hospitals who are ready and eager to take it there, but it's not free. You've got to come up with the shekels to develop the technical machine, and then the couplet [unintelligible] which cools image [unintelligible] for image analysis, et cetera, to realize the benefit. Anyway, that's another purpose that is in my view of things. So I'm not without things built up [unintelligible].
Peter, it's been an absolute delight speaking to you over these past two sessions. I'm so glad that we connected, and I feel a real personal connection to you, even through this far technology of Zoom. I'm just so glad that we were able to do this, and the wealth of insights that you have shared with me over the course of your career are really remarkable, and it's going to be the kind of record that so many people for so many different reasons are going to find value in, so deeply grateful for our time together.
Well, I'm likewise grateful. And I was tickled to learn about your personal history and really, frankly, bowled over by it. We certainly had a very obvious overlap at the starting gate. I would very much appreciate it if you'd send me the link to the book, and also to the broader theme of the State Department History Archive. I had a cousin who linked into the saga of Vietnam in a very different way. As we suspected at the time, he worked for the CIA for his entire career. And he and his wife were based in variously Cambodia and Laos through much of the war doing all sorts of things, some of which are probably in your histories by now, but were not known at the time, of the various things we did on the Ho Chi Minh trail and other ways that the CIA was part of the picture on. But he was an interesting person to talk to. He passed away a couple of years ago. And we never talked candidly about Vietnam in a way that I wish we had in retrospect. It was a very tough time, and I worry that our young Americans today are not learning well enough the lessons of history, of how this country not only can but has done the waging of the wrong wars, [unintelligible] morally and ethically [unintelligible] wrong wars, and the devastating harm that they can do. It does not temper the public dialogue in our discussions of the world today to the degree that I think we desperately need it to do. We need to have a humility, particularly the people of this country, for how we are very fallible and very capable of being misled into tragically wrong things. And I just sound like a grumpy old man saying that, I guess. So I feel that theme strongly.