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Oral History Transcript — Dr. John Wheeler

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Interview with Dr. John Wheeler
By Kenneth W. Ford
At Jadwin Hall, Princeton University
March 28, 1994

Listen to Wheeler discuss his idea of "the big crunch."

Transcript

This is one of 22 sessions of oral history interviews with John Archibald Wheeler conducted by Kenneth W. Ford between December 6, 1993 and May 18, 1995. They represent research material for Wheeler’s autobiography, Geons, Black Holes, and Quantum Foam: A Life in Physics (Norton, 1998).

Session I | Session II | Session III | Session IV | Session V | Session VI | Session VII
Session VIII | Session IX | Session X | Session XI | Session XII | Session XIII – XXII

"DEFINING MOMENTS"

The topic: Discuss some of the "defining moments." I have a little hard time pulling them up out of nothing, but I'll look at the bibliography.

Collective-model work

The one on "Nuclear Constitution and the Interpretation of Fission Phenomena," which is really the collective model of the nucleus, that paper with David Hill, provided a point of entry to many problems that I would have loved to work on more, and some of which I did work on more. The "Collective Model for Nuclei" is a title I gave my talk a year later. David and I looked at the simplest examples we could find of a particle moving in a potential deprived of perfect spherical symmetry, looking for simple ways to understand the splitting of the energy levels. That work we never published, so far as I can recall, and I should really check with David Hill what his memories are of what we had in mind to do.

Muonic atoms

That's one of the fascinating features of physics: There's hardly any topic one can enter into at all carefully without seeing that it opens endless frontiers for further exploration. The same was true of a paper which again took the nuclear field of force to have a simple average character, but this time not as any(?) field of force acting on a nuclear particle, but a field of force acting on a mu meson captured into a Bohr orbit. The fate of the mu meson undergoing its own beta decay into an electron and a neutrino. If there was anything at the start which was clear above everything else about the mu meson, it was its power to penetrate dense matter, even lead blocks, as shown by the experiments of Rossi. How to reconcile that with the emission of radiation from the mu meson as it dropped from one Bohr orbit to another, a pretty tame behavior? That radiation was detected by W. Y. Chang. I always wanted it to be called the Chang Radiation, but the word never took on. His loyalty to China and his wife's loyalty to China took them both back there a year or two after the end of the war. He ultimately became head of the Nuclear Physics Laboratory in Beijing and she a teacher of physics in Beijing. I'm afraid he's no longer living.

Elementary-particle physics

The mu meson, the pi meson, the electron, and the neutrino, and the relation between them furnished much food for thought, as Jayme Tiomno and I found in a subsequent time. That was my closest point of entry into elementary-particle physics, apart from doing a review of the subject of elementary-particle physics for a talk at the American Philosophical Society. In my talk and in my attitude subsequently I couldn't help feeling that the way to get on with the job was use the particles that nature provided in the cosmic rays and short-circuit all the business of building high-energy machines. That was too modest an approach, I'm afraid, but I confess to a feeling of great skepticism at the time that Princeton, jointly with the University of Pennsylvania, built an accelerator in the Princeton neighborhood—the Princeton-Penn accelerator. It seemed to me it was too big an enterprise financially and managerially to be compatible with physics guidance. I'm sorry to say that the laboratory shut down; it was indeed an ill-fated venture. Why didn't I speak up against it more strongly in the physics department meeting? Well, I felt that it was not I who was putting my neck on the line in building it. So that hardly defined a future for me.

My defining moment was grabbing the laboratory that Bleakney had been using for shock-wave work during the war and converting it to a laboratory for cosmic-ray physics. When, ultimately, I left for a Guggenheim fellowship in Paris, which shaded out into my Los Alamos period and Project Matterhorn period, that laboratory went under the supervision of George Reynolds, as Elementary-Particle Physics Laboratory. I should ask him to discuss what he felt the laboratory aimed at and what it achieved.

RELATIVITY - LEARNING BY TEACHING: FULBRIGHT PROFESSORSHIP IN JAPAN

Teaching relativity at Princeton in the period at the end of Project Matterhorn, the period 1952-1953, and subsequently, was a great opportunity to learn the subject. I have not looked up to see what I had in the way of course notes at that time. But I recall that my Japanese friends, particularly Minoru Kobayashi, invited me to take a Fulbright professorship at Kyoto, and there I gave talks on general relativity. Some of that material went into the subsequent book of Misner and Thorne and myself.

 

K: John, do you recall what year that visiting professorship in Kyoto was?

I would be in trouble if I try to. I'd make some mistake. I think the year is mentioned in the preface to the book of Misner and Thorne and myself. Of course, I gave the lectures in English, and I gave out notes, dittoed notes, to make it easier for my audience to follow later what I said. I was interested that there were several postdoctoral research people in the audience, and they, if I remember correctly, were associated with Yukawa and his endeavors. I first there became acquainted with the Japanese loyalty to their chief. Such and such was the interest of Yukawa; therefore they went hammer and tongs at whatever it took to follow up that interest of Yukawa. It was not for them to look around for a new idea. The Japanese legend of the 47 Ronin, the followers of Samurai who one by one gave their lives to follow loyally his footsteps was, I think, the background of these younger Japanese colleagues.

In these days when Americans asked themselves what could they do to compete better with Japan, what is there out of Japanese experience that they should be taking over, I think that they might recognize this Japanese ability to rally behind one person's leadership and follow through, whatever the cost, sometimes blindly, but at any rate follow through. It might be like the kamikaze pilots during the war who would dive a fighter plane down the funnel of an American warship, each pilot giving his own life in order to achieve something spectacular. Well, that is a kamikaze spirit of air warfare, but I had the feeling there was a similar kamikaze spirit in physics: Dive head-first into a lot of research, regardless of what the bleak end of it might turn out to be.

ORNL ADVISORY COMMITTEE

It was a truly educational experience to be named to the advisory committee of the Oak Ridge National Laboratory. It gave an opportunity to get acquainted with the work on fission and nuclear physics of some absolutely outstanding people. I can't recall that work having led me into any discovery of my own.

LATTICE APPROACH TO GEOMETRODYNAMICS

It was a payoff of being at Princeton to learn something about the method of describing solid bodies by lattice units and fitting those lattice units together—payoff in the sense that it encouraged a similar approach to the dynamics of geometry. Richard Lindquist and I found ourselves fitting Schwarzschild blocks and domains dominated by a spherically symmetric center of attraction described by Schwarzschild geometry, fitting such blocks together after the fashion in which one fits, in solid-state physics, blocks of crystal together, or fits together the wave function in such blocks of crystal, to get an overall wave function. This gave us a way to connect the time history of a universe with the amount of mass in that universe, which turned out to reproduce with striking similarity the predictions of the Friedmann model. Friedmann had dust distributed uniformly over a spherical universe, whereas the Schwarzschild cell model had that mass concentrated in lumps, but these lumps widespread because we dealt always with cases where there were very many lattice cells. Doing that work led to a feeling that the major predictions of the Friedmann model must be essentially correct.

"RELATIVE-STATE" VS. "MANY-WORLDS"

"Assessment of Everett's Relative State Formulation of Quantum Theory" wrote to add some impact to Everett's own paper in Reviews of Modern Physics. I can't recall how come it was that at that time the Reviews of Modern Physics provided a quicker, easier method of publication of some papers than the Physical Review. I can't recall any refereeing process that went on there. Bryce DeWitt later called that relative state formulation the many-worlds formulation of quantum theory, and there are numerous colleagues, especially those who come from a more than average mathematical background, who take that as gospel truth as the way quantum theory is to be understood and applied. I am skeptical myself.

THE BIG CRUNCH

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K: John, could I interject a question about the universe at large? You said once in an earlier interview that you saw the inevitability of the Big Crunch. When I was a student, we were told that it depended on the mass density: The universe might expand forever, or it might turn around and collapse. But at some point you reached a conclusion that the collapse was inevitable. Could you discuss what led to that insight and conviction?

Yes. What religious process [laughs] led me to feel that collapse was inevitable? Well, one could call it the principle of ecological clean-up. That might trigger a question about the extent to which I let what I might call aesthetic considerations influence my attitude to questions in physics.

AESTHETICS IN PHYSICS

To what extent did I let aesthetic considerations influence my conclusions about physical processes? I certainly feel that any idea that's reasonable lets itself be depicted in a picture that has some impact. If I can't make a picture, I feel there's something faulty about the idea or the thoroughness with which it's been investigated.

But here I am now talking of the universe, talking of a universe which will collapse [even] when one knows that the Friedmann model admits indefinite expansion or collapse. I have a colleague down the hall, Ruth Daly, who thinks that she has evidence that the universe is continuing to expand and will expand forever.

THE S MATRIX

I've just been looking this morning at the book on the R matrix, which was sent to Eugene Wigner by one of the authors. That R matrix was his way to express the content of the so-called S-matrix treatment of scattering processes. That S matrix was to me the only what I can call "nice" way to express the quantum mechanics of interaction of a particle with a nucleus. The fact that Heisenberg arrived at the same approach a few years later in his considerations on elementary-particle physics did not fill me with enthusiasm, because I did not find what he was doing on elementary-particle physics very attractive or likely to be the right way through. But as a tool to deal with processes to be analyzed by a more fundamental treatment, I saw nothing superior to the S matrix, nor do I now.

EXPRESSING BASIC IDEAS IN PICTURES

I'm afraid I've got so set in my ways that I have the feeling that an idea is not a good idea unless it lends itself to be stated in a nice compelling picture.

The cycloid history of the universe

What right has one to carry that so far that one talks of the cycloid, the curve made by a paint brush tied to a tire, a tire rolled alongside the side of a building? The paint brush sweeps out a cycloid curve. That's the Friedmann curve prediction of a universe that expands, reaches a maximum dimension, and contracts to infinite compaction. What right have I to think that that's justification for thinking that's the only reasonable history for the universe? Well I confess that I am prejudiced enough to stick to that view until I see any truly convincing reason to change it.

Classical vs. quantum motion in a deformed potential

The work of David Hill and me I regret not having been brought to a nice published conclusion, especially because I would like to see those diagrams of classical particle batting back and forth within a nuclear potential of this, that, or the other shape, and see how that classical diagram correlates with the quantum-mechanical wave function for the particle caught inside the same potential.

Triangles

Tiomno and I, in treating the interaction of a mu meson with a nuclear particle, arrived at a triangle diagram. It's often referred to as the Puppi triangle. I would like to find out exactly what the correlation in time was between our treatment and the treatment of Puppi. One of the appeals of that subject was the simplicity of the triangle.

Another triangle showed up in relativity. I'll have to look up in one of the books just what that triangle is. As I recall, it has to do with the relations between energy, momentum, and velocity, and the complementarity between these ideas, the use of one idea excluding the use in the same connection of another idea in that triangle of ideas. I think that that triangle is depicted in the book that Edwin Taylor and I wrote, Spacetime Physics.

Artists

I would be happy if the whole of physics could be expressed in the form of simple attractive diagrams. It's a continual challenge to me to look at the Sistine Chapel painting by Michelangelo of the creation, with the finger of the Lord reaching out toward the figure of man and giving life. I have an equally impressive diagram on how quantum physics takes its origin. I have not found a book that discusses the different motivation of painters in different ages, but I have the feeling that in the time of Michelangelo the painters and sculptors were striving to depict something greater than themselves, whereas in later eras the driving motivation, I'm afraid, was so often "I, my, me."

Jacques Mareschal is the then young French painter who gave me drawing lessons in Paris in the year 1949. I would have loved to go on with those lessons, but they were broken off at the time I left Paris for Los Alamos. I had had drawing lessons from a teacher in the Museum of Art of the City of Youngstown, Ohio in high-school days; and, of course, as an engineering student at Johns Hopkins in the freshman/sophomore introductory years of the engineering course, I had a course in engineering drawing, which was always a pleasure.

THE BIG QUESTION - QUANTUM AND COSMOS

Some of these questions were incited by the issue about a course in relativity and collapse of the universe. The business of how come the universe, and how come quantum mechanics, the Big Bang and wave mechanics, I can't help but feel have some deep connection which, when we see it, will be so impressive, so convincing, and so beautiful that we'll all say, "Why didn't we see that sooner?"

GRAVITATIONAL WAVES

To have Joseph Weber as a colleague when he came on a Guggenheim fellowship to work with me, first at Princeton and then at Leiden, was a real stimulus. He and I wrote a paper on the cylindrical gravitational waves that had been treated by Einstein and Rosen. They seemed to me beautifully adapted to mathematical treatment.

This last weekend—that is, eight days ago in Rome—I got to talking with my colleague Ignazio Ciufolini about another form of gravitational radiation associated with a millisecond pulsar. That is to say, we think of the spinning neutron star as having associated with it a dipole magnetic field. I think of that dipole magnetic field much like butterfly wings sticking out from an ideally spherical object, or essentially ideally spherical object. That magnetic field has an energy density and therefore a mass density, therefore a quadrupole moment, and this is a time-changing quadrupole moment, owing to the rapid rotation of the millisecond pulsar. I think of that, therefore, as a source of gravitational radiation of high frequency, so the mental image that captures my imagination and attention now is a nice box a couple of feet square, metal, lined with two inches of soundproofing all around, and in the center of that a tuning fork of the right frequency to respond to those gravitational waves, and next to the tuning fork a hearing aid which will amplify the sound to a point where we poor humans can begin to hear it. Well I have not yet been through the calculations to see how far that beautiful dream is from realization, but if some day I come in with a box and set it down and say, "Listen to this," why you'll know I think it will work.

GEOMETRICAL REPRESENTATIONS OF PARTICLES

Of all the unexploited pictures that continue to appeal to me, none does so more than the picture of the spin one-half of the neutrino in the language of Elie Cartan as a triad of three perpendicular vectors which are laid down at every point in space. One follows this triad through a wormhole in space and comes out, comes back to one's starting point, and compares the diagram that one has in his hand with the diagram with which one started, and checks whether there has been a rotation. If there is a rotation of 720 degrees, that's equivalent to no rotation at all; but if it's a rotation of 360 degrees, it's equivalent to a change in the sign of the wave function if one's thinking of a neutrino. So here is a geometrical representation of an elementary-particle field. What more has to be done? It's a fascinating question. What more has to be done to translate it into real payoff? For example, what's the difference between a mu meson and a K meson and a tau meson.

THE MISSING AESTHETICS OF MODERN PARTICLE PHYSICS

I think I have failed to resonate to elementary-particle physics and the expositors of the standard model for no reason so much as not having any simple geometrical picture there to appeal, to go on. I have just read the quarterly report of the Stanford Linear Accelerator, the quarterly report called "Beam Line," and there is a report of a conference on particle physics as it's related to recent accelerator work. I find that I've got myself way out of touch with the field. I should go to a conference on the subject and kick things around and get up to speed again. I think that my failure to interact more with

particle physics is hand in hand with my interest in general relativity, both animated by love for simple geometrical diagrams.

THE COLLECTIVE MODEL

A paper with Jim Griffin on "Collective Motions in Nuclei by the Method of Generator Coordinates" arose out of a follow-up of the work I had been doing back in 1949-50 with Neils Bohr on the collective model of the nucleus. How to describe adequately the interaction of a particle with the nuclear potential of this, that, or the other geometry? An attractive method regards the particle as moving in a potential of this, that, or the other character, an ellipse that might stretched out, or an ellipse that might be nearly spherical, and looks at the parameter that describes that deformation as a part of the wave function. That was the animating idea which led to our paper on "Collective Motions in Nuclei by the Method of Generator Coordinates." We had the good fortune of a visit by Rudolf Peierls at the time we were doing this work, and I have a feeling that he contributed in some essential way to what we did, but I can't recall just what it was. I continue to feel a little uneasy that we did not sufficiently acknowledge his stimulus.

>1958 SOLVAY CONGRESS REPORT

Jan Oort's invitation to the 1958 Solvay Congress on the structure and evolution of the universe gave incentive for some of us working in relativity at Princeton to pull our thoughts together in a single report—Adams, Harrison, Klauder, Mjolsness, Wakano, and Willey, and I. I don't know how many months prior to that Ray Mjolsness, then a beginning graduate student, somehow assigned to my guidance, came into my office saying, in a negative way, "I can hear the clanking of the chains," as if he was being dragooned into research. I can't recall what he finally did, and I have a very bad conscience. I should follow up what's happened to all of these students. Graves, for example, pulled together a nice discussion, but of what I can't recall just now, in a book, but somehow this never won him any definite faculty position at the university where he was. What's happened to Graves now, that would be something I would dearly love to know. All I have to do is ask Mrs. Bennett. She knows the alumni office very well and knows how to track down where people are.

This Solvay Congress report forced us to look at all the potential sources of mass density in the universe as they were envisaged at that time. I'd say that the biggest single omission that I see now is gravitational radiation as a possible contributor to the effective mass density in the universe. Kip Thorne, in his new book, talks about that meeting and about some of the disagreements there about the fate of a black hole as a signpost of the future, a disagreement between me and Oppenheimer about the fate of a black hole.

ARTHUR WIGHTMAN

I was always grateful that Arthur Wightman has continued at Princeton. Like Eugene Wigner, he was jointly appointed in the Physics Department and in the Mathematics Department. He has served a few years ago as chairman of the Princeton Mathematics Department. He got his undergraduate training at Yale, and he has a taste for exact proof, exact mathematical proof which goes beyond what many physicists are accustomed to. He wrote a book, C, P, T and All That, which came along at a good time to good effect. I should have realized better his special taste in mathematical physics, his taste for things that lend themselves to precision and to proof. The topic that I suggested to him and on which he did his thesis work was far from that; it was the capture of mesons in matter, how the meson comes in, how it gradually falls down from one Bohr orbit to another, how in the beginning there is something like a molecular entity as the meson fills the role of an electron in furnishing a resonating bond between one atom and another. The meson falls from that status to getting(?) closer. How rapidly will it lose its angular momentum? Since this problem required all kinds of approximations, it was not really something that fitted his yen for mathematical precision. Therefore I think that's why he didn't follow up the experimental work or act as a stimulator of experimental work along this line.

K: Was he your student, John?

Yes. Arthur Wightman was my student.

CAIANIELLO

[Wightman] brought us in touch with people who were doing work on symmetries. Caianiello of the University of Salerno or Naples was one of the visitors he brought who described useful new mathematical methods. Caianiello died a few months ago, according to a report I read in a recent issue of the magazine called CERN Courier. I had the pleasure to visit his center, his research center. He was concerned with a wide-ranging set of topics that I would not have encountered but for meeting him, which in turn I owe to Arthur Wightman's initiative. He had been an officer in the Italian army during the war. A good part of his men came from Naples but were not particularly in love with the business of getting out in the front line and getting exposed to fire, so he had to drive them on in the fighting in North Africa, the fighting with the British. One day, one of his men came to him and said that the men in the battalion—I'm not sure if battalion is the right name—the men were unhappy and that they were hatching a plan to shoot Caianiello in the back. So he told me what he did. He lined the men up, had them sit around in a circle, and he gave them a talk about this business. He said, "You guys don't have guts enough to shoot me." Anyway, he seemed to quell the incipient mutiny.

RADICATI

It would be wrong to forget another incident about a distinguished Italian scientist caught up in the war. This is Luigi Radicati, who was in the partisan forces—that is, the forces trying to help the Allies and opposed to the Mussolini forces. He was in north Italy and he was in an area where it was hard to know what you were going to encounter. He came across a group of four or five men in a hut, and he could see that they looked at him suspiciously. They wanted to know who he was. Well, he said he's a professor. He could very easily have got shot, but they said, "Well, how do you prove you're a professor? Recite some Dante to us." So he recited a long section of Dante. [laughs] He reminds me of Heisenberg telling me of trading his life for a cigarette.

HEISENBERG

That was when the German front was breaking up in the west, and Heisenberg wanted to get back to Munich and look after his wife and family. But Hitler had given orders that anybody who was not as his post who was caught moving should be shot by these sentries. Well, Heisenberg was making good progress getting home, and then he encountered one of these sentries, who by instructions should shoot him because Heisenberg had no visa paper to prove that he should be in movement at this time. Heisenberg talked to him, and at a certain moment that seemed psychologically good, he held out a pack of cigarettes, and when the sentry took one he figured that meant he was saved. So, as he put it to me, it was one cigarette for one life.

MORE ON GRADUATE STUDENTS

This was incited by looking at these students, and I didn't see the name of Wightman here. I don't think I ever wrote a paper with Wightman. My paper with you, Ken, on "Quantum Effects Near a Barrier Maximum" and on "Semi-classical Methods," that's an area that still intrigues me enormously, and I'd love to see more done in that field.

I see here a paper with Robert Fuller as a co-author. Robert Fuller had been at the same college in Ohio where Enrico Fermi's son—I think it was Julio—was going. He somehow managed to come to Princeton before he had finished his undergraduate training and started graduate work. He is now at the University of Nebraska running a project, and what is the project on?

K: I think it's providing resources to high school physics teachers on a compact disc.

Yes. He certainly had a varied career. President of Oberlin College at a time of trouble, President, if I remember right, for three years during the years that I call the "I, my, me" years, when so many college campuses were troubled. Then he got a job teaching science in one of the Seattle, Washington schools; this was a troubled district. I don't know whether it was all black or all ghetto, but he found that when he talked about weighing things there was not a great deal of interest. He concluded that what they were really interested in was locks—how you pick locks. So he gave a complete discussion of that subject, and he held the attention of the students. [laughs]

He and I ended up one summer, if I remember right, at the University of California at Berkeley where I was giving a course—I think it was in nuclear physics—and he was along as a graduate student. That's when we wrote a paper on the issue that Neils Bohr had raised: Could you ever get through a wormhole before it pinched off and blocked the way?

H-BOMB IDEAS

We had been talking about the H bomb business and the essential idea, and I never did check up as to whether we could mention that idea. Carson Mark: I don't know whether he indicated it had been declassified or not.

K: He thinks probably not, and Lillian Hoddeson also thinks probably not.

I see.

K: And both of them think that the current people in declassification in the Department of Energy are very, very strict and conservative in their interpretation—even to where they discourage discussion of things that are in fact already unclassified, because they may still be considered sensitive. There's this new category of "unclassified but sensitive."

A FLUID DYNAMICS PROBLEM

David Sharp and I did a paper on what happens at a front where there is liquid—the Taylor instability, which has long been understood—but what if there is a magnetic field present? What does that do? I see that work was reported in an IDA (Institute for Defense Analyses) report. There are reports of mine that I did at Chicago and at Los Alamos and here in Princeton, Matterhorn, but I don't know how to get a bibliography of them.

A GEOPHYSICS PROBLEM

I've been talking recently with my oldest granddaughter's husband—this is Albert Leger—about the age-old problem that the geologists have: From what depth do the upwellings come that one sees in the Mid-Atlantic Ridge and in Hawaii and in volcanoes generally? Is the depth the depth of the mantle, or is it greater? The idea we were talking about is this, that we know from Elsasser the mechanism by which the earth generates a magnetic field. That is a set of currents in the earth a little like boiling oatmeal—slow moving, rising in one region, going down in another, with maybe seven zones—it could be five, it could be eight—but maybe seven zones of this circulation. Anywhere where there's a magnetic field, this current of conducting material moving through the magnetic field gives rise to a voltage and a current, and this current generates a further magnetic field, so there's a whole interlocking set of circulations of electric currents and of magnetic fields which is responsible for the general magnetic field of the earth. The interaction with the rotation of the earth is such as to make the system unstable if it gets out of alignment by too large an angle with the earth's axis. Well, if one accepts that picture—and not all geologists seem to have caught up with it yet—if one accepts that picture of Elsasser, which I learned about through the geophysicist at the University of Newcastle upon Tyne. (I was trying to remember his name now. He comes from the island of Jersey originally. And after retiring from the University of Newcastle upon Tyne recently, he took a position at the University of Alaska at Fairbanks, where he spends half the year. But now he's finished his half the year and he's at Imperial College in London the last I knew.)

The currents within the earth develop a magnetic field, and this magnetic field, being cut through by more currents of matter, generating more electric currents, more magnetic fields, as envisaged by Elsasser, was supported by the thinking of Keith Runcorn and the experiment of his graduate student, Stevenson. That model, I think, would be interesting to use as a way to deal with the rising current of magma that powers a volcano or the building of a Pacific island. It would be interesting to look for the magnetic field associated with that localized uprise. Maybe in this way one could settle that longstanding difference among geologists as to how deep the layer is in the earth where the juice moves.

WORK WITH BAIERLEIN AND SHARP

A paper of 1962 with Ralph Baierlein and David Sharp was inspired by the work of Tomonaga on what one could call, and I think was called, bubble differentiation—the amount of alteration that occurs in a magnetic field or an electric field when the spacetime hypersurface on which it's calculated is moved forward after the fashion of a bubble. This paper of Baierlein and Sharp and mine deals with the three-dimensional geometry as a carrier of information about time.

INVERSE SCATTERING PROBLEM

In a book on the 60th birthday of Eugene Wigner, edited by Bargmann, Goldberger, Treiman, and Wightman, I found myself dealing with the inverse scattering problem; that is, how to deduce from scattering as a function of energy what the curve is for interaction between the scattered object and the central object, the curve for interaction energy as a function of separation. I think more work could be done on that problem. Fascinating question.

BRIEF COMMENTS ON AN ASSORTMENT OF PUBLICATIONS IN THE 1960s and 1970s

The absence of a gravitational analog to electric charge is a paper of 1962, which capitalizes on work of William Unruh, but still raises the question, "How can one best relate these two fields, and why should there be just these two fields? Inertia here arises from mass there was a thesis of Ernst Mach. I like always to see that spelled out more fully. That's the theme of a paper of 1963, and it's the theme of a book that Princeton University Press now has in process. At the end of this month of April 1994. I expect to get proof of the book with the title Gravitation and Inertia, jointly by me and Ciufolini.

A paper with Seymour Tilson, December 1963, on the dynamics of spacetime reminds me how dangerous it is to let a science writer try to describe something that's beyond him, because you find yourself spending enormous time getting him to rewrite what he's already written. You could write it and say it yourself quicker.

The Atoms for Peace Award, given by President Eisenhower to Neils Bohr, was the first of this series of awards. Strauss—Admiral Lewis Strauss—I think had persuaded President Eisenhower to back that medal. At any rate, I found myself involved because Killian, President of MIT, was charged with arranging the ceremony in Washington at the Great Hall of the National Academy of Sciences and asked me to be the opening speaker. Then I found myself told by Eisenhower's staff that I would have to shorten it up. But I was very pleased at the end of my talk to meet in a little intermission Supreme Court Justice Felix Frankfurter, who complimented me on the talk. I had met him, thanks to Neils Bohr, at a dinner in Washington on some other occasion at the residence of the Danish Ambassador to Washington. Frankfurter is, as I understand it, the man who persuaded Franklin Roosevelt that he ought to see Bohr and hear Bohr's thesis that the only way to ensure a peaceful world is through an open world.

"Geometrodynamics and the Issue of the Final State" is the title of a paper I did in 1964. There the central concern that I had was one that one summarizes in the word [term] "the black hole." What goes on inside of a black hole? That's the article where I felt myself forced into the black hole. That is more than 200 pages long and would serve to be a small book.

I've always enjoyed talking with Fred Hoyle and with Jayant Narlikar of Bombay, but it was not until 1964 that I found how breathtaking it is to be involved in writing a paper with them, because some of the traffic rules, the "go slow" that I am accustomed to, were rules that they were ready to disregard. It's always interesting to me how the nature of the audience influences what one's going to say. If it's in another country, it offers the stimulus for another perspective.

To do a review such as I did on the topic of fission in the 1966 second edition of the Condon-Odishaw Handbook of Physics was not a good way for me to learn anything very new.

When a book such as the book of Harrison, Thorne, Wakano and me, the book on gravitational collapse, is translated by a Russian as distinguished as Yakov Borisovich Zel'dovich, one knows that the actual translation is not done by him but by some of his assistants. But one also knows that he gives the subject his attention. I really valued his comments on the subject.

A 1968 paper in the American Scholar and in the American Scientist was the first occasion when I used in print the word "black hole."

It makes me squirm to see an item, remarks I made on the December 2nd, 1968 receipt of the Fermi Award from President Lyndon Johnson—squirm because I did not at that time appreciate all the hard work that had been done by friends and colleagues in assembling the letters of recommendation that won me the award. I think Hood Worthington was a leader in doing that, and he was one of the very first to leave this world, one of the very first of my du Pont colleagues. I'll treasure always the memory of him at an evening performance in Wilmington of Gilbert and Sullivan. I think it was Iolanthe, he singing "Wend My Flowery Way."

I'm intrigued to see that this stimulus of speaking before an international audience must have been at work in inciting me to develop the term "superspace" in talking about the nature of quantum geometrodynamics, because that I see in the title of a piece that I did in 1969.

As a trustee of Battelle, I found myself drawn into making the Battelle-Seattle Center, a conference center for conferences in mathematics and physics. Fred Milford, of the Battelle staff, was for that idea, and he and I drew Cecile Morette-DeWitt into it because she had had such experience running the French conferences known under the name of les Houches. I'm afraid I had to serve as mediator between Fred and Cecile in some of the discussions, but the whole thing went well and would still be going on if Battelle hadn't run out of money. So now it has to run conferences for which it charges.

I ought to go back to a 1970 book on relativity which Witten and two other authors edited. I wrote an article on particles and geometry. What did I say then that's still true and might help me on my way, and what ought I to disown, and what does that disowning mean in the way of learning that would be a useful experience?

Here is the item number 183 in my bibliography, the item by John C. Graves, the book that he published on relativity. I'd love to find out what's happened to him.

It was around 1970 that this dynamic Italian postdoctoral showed up here, Remo Ruffini. At his instigation, we did an article for Physics Today called "Introducing the Black Hole." We also did an analysis of gravitational radiation and the possibilities of producing it and of detecting it

But the book with Misner and Thorne on Gravitation of 1970 had a more lasting influence. I think something like 70,000 copies of that book have been sold. At almost every big meeting I have colleagues come up to me asking me to autograph it.

BRIEF COMMENTS ON PUBLICATIONS

(continued)

A 1969 paper comparing Mendeleev's atom with a collapsing star gave occasion to speak about the so-called, I think I called it, the necklace-shaped orbit of an electron around a nuclear center of force, and the how and the why and the consequences of an orbit of that shape.

On a visit to the Soviet Union, Charles Misner and I found ourselves pressured to supply a paper on some topic in relativity, and we did one on conservation laws and the boundary of a boundary. He taught me so much in the course of our doing that paper that it actually forms the backbone of a recent book of mine called A Journey into Gravity and Spacetime.

The work that I did earlier with Kenneth Ford was surely a guide into a later paper with Joe Ball and Ed Fireman on absorption of light and the charge oscillation in the Fermi-Thomas statistical atom model.

The Dirac birthday conference at Trieste under the stewardship of Mehra gave a chance to review many subjects. My own paper, "From Relativity to Mutability," I found challenged by my wonderful Danish colleague Moller. Moller felt that it's possible to give a definition of the local energy density of a gravitational field in contrast to, I think, the general opinion of the community. And I had to stand up for the general opinion of the community against the attacks of Moller.

Thanks to the initiative of Ruffini, he, I, and Martin Rees managed to get a book out in 1974 on Black Holes, Gravitational Waves and Cosmology. I had not realized how many reprints Ruffini had tacked on at the end until I received a letter from William Press, one of our colleagues, asking for, if I remember right, a $75 payment because we used some diagram of his without having got his permission. That I hope has taught us all how to behave better. I think Bill Press and Kip Thorne must have been behind that spoof of a paper of mine, the spoof that they called "Science and the Transmogrification of Destiny."

The most challenging occasion of several years was the anniversary of Copernicus celebrated in Washington in the building of the National Academy of Science. I had persuaded Heisenberg to speak, but I had, of course, to speak myself. It forced me to speak on a topic as broad as the one "The Universe as Home for Man."

Looking for something that was deeper than geometry, something that might be the foundation for general relativity, I find encouraged by giving a name to this search: "Why pregeometry?" But I believe now that my whole direction of search was too much mathematical, and not enough idea-driven.

I see that 1977 is the date of the Russian translation of the book of Misner, Thorne, and myself on Gravitation. I know Braginski had a major part in seeing that that was done, and he tells me that he had 50 copies of the publication for his own institute and two copies in his own office, and within something like a year all of them were gone.

With Charles Patton I did a paper called "Is Physics Legislated by Cosmogony?" The most useful outcome of that was a criterion of selection of ideas, exclusion of ideas, based on whether the idea in question admits of having an origin and passing out of existence.

1978 was the date of publication of my first paper on delayed choice experiments. I mentioned, I believe, there—I hope so—that the idea had been mentioned in a tiny phrase by Neils Bohr and in a passing way in a paper by Weizsäcker, but I think I should make sure in some forthcoming publication that Weizsäcker gets more credit than there.

The closest I ever came, prior to now, in doing an autobiography is item 241, "Some Men and Moments in the History of Nuclear Physics," in a book edited by Roger Stuewer.

"Collapse and Quantum as Lock and Key" is a title of a paper I'd like to read in order to get some idea.

Parapsychology and "where there's smoke, there's smoke" is a theme I have had to come back to more than once.

There's a 1980 paper in which I doubt if there is anything presently useful, but I'd like to look. It's a paper called "Pregeometry: Motivations and Prospects." That's the idea of looking for some foundation for geometry which is more loose-jointed than geometry itself is.

I found myself asked to do a biographical memoir on Einstein for the National Academy of Sciences. A colleague in biology at Indiana University—was it Sonnenschein or Sonnenfeld?—told me later that he summoned his graduate students and read it out loud to them, with tears in his eyes. So it must have affected somebody.

I think it's in Seattle, Washington where R. C. Kirkpatrick lives. He sent me a manuscript, "The Physics of DT Ignition in Small Fusion Targets," with my name on it as a co-author. I didn't see anything wrong with it. I didn't quite understand why I was to be listed as a co-author, but so the record is.

PUZZLE OF THE QUANTUM

Go anywhere, talk to anyone, raise any question, make a fool of myself a hundred times over! That I said I'm willing to do if I could give me some idea about the big questions. I think of that especially in connection with trying to understand the quantum. I see the various papers of mine over the years where I've talked about the quantum. Maybe I should make a fool of myself by going back and reading them. Here is one called "The Elementary Quantum Act as Higgledy-Piggledy Building Mechanism" of 1981.

MORE BRIEF COMMENTS ON PUBLICATIONS

A paper that has a little of the flavor of the things that you and I have done together, Ken, is a paper here by me and R. S. Armour, Jr. on "A Physicist's Version of the Traveling Salesman Problem," because that's a famous problem for being exponentially difficult from a computer point of view. Yet by treating it on a statistical basis, it lends itself to simple analysis.

"Gravitational Collapse of a Gravitational Wave Via Geon Transition State" is a paper that I'd like to see developed further.

The book of John Barrow and Frank Tipler, called The Anthropic Cosmological Principle: They did me the honor to ask me to write a preface or forward, which I did, but I think I was a little too enthusiastic about the anthropic principle, and I would give a more qualified statement about the idea now.

"Nanosecond Matter" is a discussion, among other things, of the properties of a fluid made of molecules of super-light hydrogen, one positron and one electron. There are many positrons and electrons in the space around some powerful astronomical emitters of gamma rays. It would be lovely to discover a mechanism by which that stuff can be, and is sometimes, expanded suddenly and cools and condenses to give a liquid, just the way one can liquefy hydrogen by sudden cooling.

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