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Credit: SLAC National Accelerator Laboratory
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Interview of Tsuneyoshi Kamae by David Zierler on April 20, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
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Interview with Tsuneyoshi (Tune) Kamae, Professor Emeritus, both of the University of Tokyo, Department of Physics and of SLAC. Kamae discusses his current work configuring digital devices on science education for the visually impaired, and he recounts his childhood in Himeji and then Osaka, Japan and his early memories of World War II. He describes his undergraduate education at Kyoto University and his developing interest in physics and the opportunity that led to his acceptance at Princeton to work with Val Fitch on the root cause of CP violation. Kamae describes his postdoctoral work at KEK in Japan, where he studied the internal motion of the proton inside the nucleus, and he explains the circumstances that led him to LBL and then SLAC to work on the Time Projection Chamber. He discusses his involvement with the SSC planning and how he became involved in X-ray astronomy. Kamae discusses SLAC’s embrace of astrophysics under the leadership of Burt Richter, and he reflects on some of the cultural differences in physics environments in the United States and Japan. At the end of the interview Kamae shares his hopes for the future of the education program he is developing, and he discusses some of the strategic challenges Japan is facing in light of its demographic trends.
This is David Zierler, oral historian for the American Institute of Physics. It is April 20, 2021. I’m delighted to be here with Dr. Tsuneyoshi Kamae. Tune, it’s great to see you. Thank you so much for joining me.
It’s a great honor and a pleasure to be on this interview.
Tune, to start, would you please tell me your current or most recent title and institutional affiliation?
Yes. I am professor emeritus, both from the University of Tokyo Physics Department and SLAC, Stanford University. And yes, I am still associated at the University of Tokyo, because I get a grant from our funding agent, Ministry of Education.
When did you go emeritus, both from the university and from SLAC? What year was that?
I went emeritus in the year 2000 from the University of Tokyo and moved to SLAC, Stanford, in the same year, and retired from SLAC in 2011.
And in what ways have you remained connected with SLAC over the past 10 years?
My daughter lives in San Francisco, and also I keep a small apartment in San Francisco, because I used to go back to Bay Area every—twice or three times a year, before this COVID-19 really cut me off with the University of Tokyo, I do mostly through email, telephone, and others. They are open, but they do not really appreciate me going into admin office and meet people.
Tune, how have you done in the pandemic, both personally and scientifically? What’s been difficult, and what’s been easy for you?
Well, to me, because I have already retired, and so more or less the effect is probably minimum compared to the active professors either at Stanford or in University of Tokyo. And I’ve been meeting—joining through Zoom, but for the collaboration it was a very familiar format. Fermi Large-Area-Telescope gamma-ray astronomy project, being so international, we used to have a meeting in Zoom long before Zoom became popular. It had been another kind of conference meeting application similar to Zoom. It was an application offered by Caltech from the year 2002 or 2003 on. I don’t remember exactly. So, that format doesn’t change, but most of the problem is, you like to really see in person and ask for advice.
For example, I’m so isolated, not even with a student, and many of new developments in software, I’m not necessarily following. I’d love to go to SLAC and drop in some experts’ office and ask: “How do I run this program? Why do get this error message? How do I”—and that kind of thing. But I’m slowly moving out of gamma-ray astronomy, what I did at SLAC, and beginning to do some development of assistive technologies, especially for visually impaired. When I began my career at the University of Tokyo, one physics student lost eyesight slowly, and that was the late 1970s. And it didn’t occur to me how difficult it would be if I lose my eyesight.
At that time, there’s not much assistive technology available. I was then working with Berkeley folks for a collider experiment at SLAC, PEP-4, with Dave Nygren’s group. One day, I was working on the Berkeley campus, and there’s a blind guy. So, I asked him: how do you do your work? He told me about a simple program—what’s now called a screen reader, for WordPerfect. You’re too young to remember that name. But long before Microsoft invented Word and all of those, there was WordPerfect.
Tune, maybe I’m a little younger than I look, but I do remember WordPerfect, and I’ll prove it to you, because the maker was Corel. [laugh]
And there was no Windows. It was DOS/V. Then he introduced me to a younger programmer who was supporting him, and he was very kind to give me most of the software he had developed. So, I got back to Tokyo and fixed some problems I faced in running the program and installed to a DOS/V machine. Another challenge was to send voice to a speaker or speaking aloud. TTS was a big and expensive program. There was a very expensive hardware called DECtalk. I remember that’s price was my one-year salary [laugh] at the University of Tokyo. So, I decided to make a very simple amplifier and speaker, which I did, and I gave that set to the student who was slowly losing eyesight.
And since then, I was modestly—maybe 5 percent of me—connected with the visually impaired community, especially in Japan. So, after getting back and retiring from SLAC in 2011, I found there are a few very well-developed screen reader available in Japanese, or whatever language you use. So, I decided I should really work more on the mobile phone. And iPhone was—or is still—the choice for the blind people in Japan, as well as worldwide. But programming for the iPhone was too much for me. Too difficult. I could program a little on Java, and so I decided to pick up Android. And so, I’ve been helping and producing some Android devices configured for the blind.
Soon I realized that in the area—I mean assistive technology for Android -- Google is making huge progress. I don’t mean, what we have is perfect. So, I decided something that big business would not do. One thing I am developing is a tactile book reader. I can show you—sorry, I shouldn’t spend too much time on a side issue. This is the book I made. It’s a manga book. You may not be able to see. It has a transparent profile on the color drawings. It comes with a Power Point file and if you put a page of the book on top of the Microsoft presentation of the PowerPoint, a miracle happens. I set up a macro that read-aloud the region mouse or finger touch or hover over. So if you touch that part, the program says “boy’s eye,” and “boy’s right hand.” So you know, right away what you are touching.
It is very difficult for blind people to understand what a tactile profile or a tactile line drawing means. But that way, they can train themselves slowly to recognize the shape or the object. I published this book about six months ago, and suddenly, I’m losing a lot of money. [laugh] I’m not making anything. But nevertheless, I thought this way, blind people should — you know, practice or train themselves, just like reading braille. It is not that easy.
And based on this, I’m now beginning to write some short—how do you call it—teaching material on science like algebra, and physics using this kind of material. But I’m not trying to write a full textbook, because if you are teaching at school, every scientist has their favorite way of teaching. [laugh] I know, because I have my favorite way of teaching. If you’re teaching astronomy, for example, you definitely need the distribution molecular or atomic hydrogen in our Galaxy, as well as the temperature map of the cosmic microwave background. So any textbook has a certain set of illustrations or figures which every professor refers to. So, I’m preparing the kind of books which can be put onto the touch screen, where a PowerPoint presentation is displayed.
I’m also developing a web-based presentation. And if your finger touches on a tactile profile, you hear voice. Blind people will feel a profile, a transparent tactile profile, for example, the profile of your face, or the microwave background contour together with some explanation of the object—the computer speak aloud: “This is the galactic center. This is the constellation Orion. This is the highest of 5 levels, of the cosmic microwave power distribution.” And that way information you hear will be tied to your cognitive memory conveyed through your finger.
This concurrent input helps to register knowledge to your brain, whether you’re blind or sighted, or you know, some kind of disability. If you associate the shape brought through the tactile profile, things deposit in your brain much, much faster. And that way, I mean, for example, geometrical shapes—whatever shape you have to teach in mathematics, or gauge theory, how A and phi works to describe electric and magnetic field The vector field could be represented by transparent tactile arrows on color drawing. And no matter who teaches, in physics, you have to go through Aharanov-Bohm effect or that kind of thing. And so, I’m making, piece-wise, these materials–color illustration superimposed with tactile lines and descriptive explanation—when handicapped people touch the profile and my setup will explain it via synthesized voice to them.
Tune, to what extent is this program that you’re developing culturally neutral? In other words, it doesn’t matter if you’re from Japan or America or Brazil, or anything like that. Is it universal, or are you thinking specifically in terms of particular cultures?
I suppose if you define physics as a culture, my program is neutral, [laugh] which we believe, right? It’s very simple to translate to Spanish or Portuguese or English or Japanese or Chinese, because all you have to do is change the text, which is a small portion of my work.
Tune, to give an example of where we are with COVID right now, in Japan, how are things looking right now? Are people getting vaccinations? Is it starting to look back to normal?
No, no. They only started for the medical staff, but overall—how do you say—the spread of COVID-19 is probably two orders of magnitude smaller than USA. When compared to Germany, maybe 5 percent of Germany, because probably the Japanese behave better, regarding masks and whatnot. But still, the spread is again climbing up, because the British or UK variant of COVID-19 is now overtaking the original COVID-19. Doctors say this variant is more contagious or stronger than the first go-around. So, definitely people are very, very cautious. Yeah.
Tune, let’s go back to the beginning. I’d like to hear about your parents. Tell me about them.
Right. Right. I mean, I was born in 1940, just before World War II started between the US and Japan. And my father was a medical doctor, and my mother was a housewife and housekeeper. But she also comes from a long line of medical professionals.
Where in Japan are your parents from?
My father originated from Himeji. Himeji is and probably best known for the beautiful, very big castle. If you have a chance to come and visit Himeji, they kept—the US didn’t bomb the castle and old town. So, you know, just like probably bigger than any European castle and very well maintained. So, we lived very close to the castle, and because of that, fortunately we are not affected by the bomb or any attack, because I think the US Army already felt that you have to save the castle, because of the historical importance.
Do you have any early memories of the war, even as a 4-year-old or a 5-year-old?
Yes, definitely. Definitely. I mean, my father was a medical doctor, and the Japanese Army ran very short of medical doctors. So, although he was older than the average medical doctor who was drafted, he was drafted in 1944 and sent to Singapore and Malaysia. But fortunately, he stayed in the hospital. And so, I remember sending him off and receiving mail once in a while. I remember a mail from the island Celebes now a part of Indonesia, reading “In a week, I will be in Singapore,” and that kind of letter. And I also remember when he came back here several months after the war.
Most of the medical doctors, Japanese, could not come back immediately because most of the areas that the Japanese Army occupied were very short of medical doctors. And the worst was in Siberia. The Soviet Union kept all the Japanese medical doctors, and they treated them very well, but most of them could not return to Japan almost 20 years. My father was fortunate, because he was under the British and Australian army, and he was asked to serve the local Malaysians for a year and then released.
When did you reunite with your father?
’46. Yeah, after the war ended.
Did he ever talk about his experiences? Were you able to get information and stories from him?
Oh, yeah. Yeah. You know, my father didn’t really see the worst part of the war, because he was stationed in a big hospital in Johor Bahru. It’s a big city across a narrow channel from Singapore. And I think he maintained very good relations with the local nurses, because 20, 30 years later he returned for reunion. He was invited by a group of local nurses to go back to Malaysia. So, I think these medical staff who worked with him probably had a good memory of him. I am very relieved. Some of the people really had to go through such a worst kind of war. I mean, especially the Japanese Army. And my wife’s side, a younger medical doctor had to travel with the army, and most likely, he had to abandon many injured soldiers. So, most of these younger medical doctors would never talk about the war. It’s such a devastating memory.
Do you have any specific memory of the atomic attacks on Hiroshima and Nagasaki?
No. No. Himeji is so far away. But I remember, Himeji is known for the classical Japanese castle. What we call a “castled city,” retaining an old “feudal city.” But the seaside of Himeji was every industrialized—and actually was making some weaponry. So, it was bombed heavily, we could really see the flame flaring up in the other parts of Himeji. So that’s, for me, the memory of WWII.
Tune, do you have the sense that you grew up in a devastated society, a postwar Japan that was really struggling to rebuild after the war, or it felt more normal to you?
Yeah. I mean, if you are five or six years old, you don’t have to suffer as much as if you are 16 or 17. To me, if you recall it, it was really hungry every day. [laugh] But never as bad as one might think. When you are____ 5 or 6 and all the other kids around you are in the same situation, you somehow don’t feel that unhappy. You live, you know, a “normal” life. I mean, because it is not—the war didn’t continue, so as long as you stay healthy and live a modest life, you are safe. Not like in Syria, or you know, some part of the Middle East.
Tell me about your schooling as a young boy. Did you go to a large school or a small school?
No, a regular public school. So, as soon as my father got back from the war, he decided to move to Osaka, a biggest city, to have open a clinic. Before the war, he probably had some ambition to be in academia in the medical school in Kyoto. He graduated from Kyoto University. But after the war, it was just impossible to live in academia unless you were in a super wealthy family.
Tune, when did you get interested in science?
Okay. I think as a—probably that Yukawa got the Nobel Prize had probably impact to me. You know, I mean, Japan always considered to be very inferior, technically, to the US. Although there was a few scientists before the war who should have gotten a Nobel Prize, but because of European dominance, many of the works by Japanese were more or less ignored. But Yukawa—fortunately, Oppenheimer—I had luck to meet him in Princeton—insisted that Yukawa get a Nobel Prize. So, that’s how he got it. And that has a big impact for me and many, many others.
It was a point of national pride for Japan when he won the Nobel Prize.
Yeah, exactly. A big recognition.
How old were you when he was honored with the Nobel Prize?
I don’t remember, but probably I was in fifth grade or fourth grade, something like that.
Oh, so even young, this had an impression on you.
Yeah. I mean, right. He was on radio and newspaper.
And it was physics. It was specifically physics that you became interested in?
No, I wasn’t that sure, but I did quite well in math. And physics only comes after you come to high school. Right? So, I was good in math. Because my father worked for one year under the British and Australian army, when he came back to Japan told us, “You boys”—I mean, I had brothers. [laugh] “Now, it is English-dominated world. So, you have to learn English.” And so, very close to our house in Osaka, there was an Anglican church, where English was taught. So, my father suggested, “Why don’t you go there?” So, my brother and I went there, to take evening classes. And when you are 6 or 7, you pick up much faster than adults who came to the same class. So, we became teacher’s pet. [laugh] Look, these small kids pronouncing this much better than you big guys. [laugh] So, we loved to learn and read English.
Tell me about your high school.
High school is the oldest high school in the Osaka area, and probably still the best public high school there. I went through the regular public schooling system. Some had gone to private high schools, but my father probably thought you guys will survive well in the public schooling system. [laugh] The high school me and my brothers went was the oldest public high school in Osaka, and is an excellent place—I mean, for me and my brothers. The school let students be free. For example, I did most of the math exam much faster than other students. I told to my math teacher, “I don’t need one hour for the exam. I will submit in 30 minutes.” [laugh] So, every exam I turned in 30 minutes. And then my math teacher said: “When I was your age, I could solve much faster than you.” [laugh] And he was a graduate from Kyoto University, and he was such wonderful teacher.
And so was my physics teacher, who was a PhD from Osaka University and studied nuclear science. But when we went to high school, a job for PhDs in science was not scarce, so they first decided to teach in high schools. And many of my high school teachers later became professors in Kyoto and Tokyo. So, they could teach quantum mechanics and whatever higher level we were looking for. So, my generation was, in a way, very, very fortunate. There was freedom after the war, and bureaucracy was not prevailing in Japan. And schoolteachers had all the freedom to pick a few smart kids and teach them privately. And my physics teacher said, “You don’t have to come to class. Go to the library. There are textbooks on quantum mechanics, this and that.” And I picked up whatever I wanted and read it.
Tune, what options were available to you for college? Did you want to stay in Japan? Were you thinking about international study at this point?
No. I could have gone to the US, but still, it didn’t occur to me until I finished my undergrad. So, my father and my elder brother and many of my male relatives went to Kyoto University. It’s really an excellent university. But I thought: “Gee, I should go to some other university.” So, I went to the University of Tokyo.
And in the Japanese system, do you declare a major or a focus right away? Or, that comes later after a more general education?
In my generation, the decision could be made later, in the second year. So, at the University of Tokyo, you could choose either science, engineering or even law or economics. You know, you had very crude division. And when you go to the department after the third and fourth year, you could switch to another field if you wished to. So, it’s like the US system.
When did it become physics for you?
Well, I wasn’t sure. I mean, I thought it may be cool to become a diplomat. [laugh] In retrospect, I made the right choice. One of my friends at University of Tokyo was the son of a very famous diplomat, the ambassador to the Soviet Union. He told me: “Don’t go to diplomacy. All congressmen will come and treat you like a servant.” [laugh]
And you listened to this advice, of course.
Yeah. So, a diplomat—although you may have an honor of greeting to Queen Elizabeth or all other VIPs, but the real power and the real things you could do is so limited, probably the same for you as in many other countries including Japan.
Tell me about your physics education as an undergraduate.
Well, a shocking thing happened to me when I was at the University of Tokyo. I loved the mountains, and I joined a climbing club. I mean, rock climbing and all others. And the leader was so ambitious, and we tried to climb a very difficult wall in Japan in snow-covered condition. And we began to start. It was snowing. I was the youngest. I said, “No, we shouldn’t go. It’s snowing.” I mean, the crampons would not work for soft snow. So, my group didn’t go and stayed in a cave at the bottom of the wall. But the other groups tried, and continued. When you’re 18 or 19, and lose friends that way, you don’t know how to cope with the tragedy. So, I didn’t study that hard, and I roamed around, traveled in Japan. I read books too, without any deep thinking, I got a master’s degree from the University of Tokyo. And then I thought: “Gee, I have to choose what profession you’re going to be.” I really wanted to continue on physics.
Now, was your master’s degree in physics?
Yeah. And then it occurred to me, it is my responsibility. You shouldn’t rely on your advisor. I went to the library, read many, many papers, although I didn’t understand them well. And it really struck me that neutral K and its anti-particle can mix. And early in 1960’s, there was the first sort of experiments to study if the weak decay, violates the CP symmetry. And through this second-order weak interaction, K0 and K0-bar can be mixed and form what’s known as KL, long-lived K0 and KS, short-lived K0. And it fascinated me—I knew quantum mechanics, but it was such a fascinating thing. So I thought: “This may reveal something new.” I wrote later to Val Fitch at Princeton. [laugh] I’m interested in working with you and studying neutral kaons.
Tune, let me ask at this point: there’s a very big world of physics out there. Why, of all things to grab your attention, was it this topic, and what Val Fitch at Princeton was working on?
You know, at that time, in the 1960s, there’s only a few people who are working on the neutrla kaon system. The majority of them was—it is all gone now—phenomenological hadron physics such as Regge theory and what’s called t-channel – s-channel duality, which is also fascinating in early days, which ended up in the quantum chromo-dynamics. So, there’s a lot of people, the majority of the AGS experiment at Brookhaven, was heading to that direction — strong interaction. And only, I would say, the Princeton group and you remember Al Mann at Penn. And there’s only a few groups who are really doing experiments. I didn’t know who was who, but anyhow, I wrote to Val Fitch and he kindly responded to me, “Why don’t you come?”
He must have been impressed that this student from Japan was interested in this specific topic and wanted to come halfway around the planet to come work with him.
What year did you arrive at Princeton?
And what was Val working on at that point?
The famous experiment was just over. He had finished analysis of the data and gave me a small project to work on. But I had applied for a fellowship which was a very difficult one to get. But to my surprise, I got it. It’s called the David Sarnoff fellowship. It was started by the chairman of RCA. And that gave me a “free pass” to the US universities I had applied for. I think I got accepted because the Sarnoff fellowship is so prestigious.
Tune, had you ever been to the United States before?
What were your impressions of Princeton when you first arrived?
Oh, what a beautiful campus and town! [laugh] I knew how Cambridge and Oxford look by photos. But Princeton is in a similar setting—Oxford and Cambridge in the New England-ish environment. In a beautiful, wooded region. Right? Cambridge and Oxford is tightly packed city. I couldn’t believe the US could maintain such a university on a private fund. US was so wealthy, far more than I’d thought.
Were there other Asian students there at the time?
No, Asians were very rare. There was one classmate—I don’t know what he does now, a student from Singapore, a son of a billionaire shipping giant. But nobody else. There’s a couple of Europeans, but very few.
Who were some of the other professors in the Princeton Department of Physics that you may have become close with?
Yeah. I was so impressed—still I regard him as the best physicist I have met -- is Prof. John Wheeler. He was such an amazing person. I mean, he would answer any question you’d come up with, full-heartedly.
What classes did you take from Wheeler?
Oh, I took various, but most impressed was general relativity. You know that thick book? Kip Thorne, Misner, and John Wheeler.
Was Val Fitch your advisor eventually?
Yeah. Yeah, he was.
And how did you work with him in terms of developing a thesis topic? Did he give you something to work on?
Yeah. I mean, we had a series of discussions with professors. I wasn’t so sure what to do after arriving at Princeton. David Wilkinson—unfortunately, he passed away—came to me and said, “Why don’t you come and work with me on the cosmic microwave?” And so, I studied the topics starting from what little I knew. This was just the time the 3-degree background was discovered by the Bell Lab people. And Robert Dicke was proposing, you know, his alternative theory of relativity.
Robert. Robert Dicke.
Yeah. Right. But as far as I could study, you know, the next sort of observable, after the 3 degree one, was probably, 20 years from then. Professor Wilkinson also agreed it is not that easy. So, I thought: “Gee, [laugh] how can I leave graduate school without any paper?”
Tell me about your thesis research. What were some of your findings?
Yeah. I decided at that time, just after the CP violation was discovered, to find out what is causing the violation. TD Lee proposed it must be higher order effects of electromagnetic nature. And few really believed in TD Lee’s theory. It became very important to measure the difference in eta+- (KL decay amplitude to pi+ and pi-) and eta00 (KL decay amplitude to pi0 and pi0). And the difference is a measure to tell whether TD Lee’s theory or what we then called the superweak theory is correct. In retrospect, this is the first test whether the violation is due to Kobayashi-Maskawa type mixing in the mass matrix. TD Lee predicted the difference to be large. So I said, “I want to measure the difference between eta+- and eta00.” And I told Val my wish. Gosh, it was thought to be a difficult, difficult challenge. But I thought I might as well challenge.
Tune, what were some of the advances in theory at this point that may have been relevant to your research?
Oh, yeah. TD Lee’s theory was a very ad-hoc theory, and so was in some degree what’s called the superweak theory. At that time the bottom and top quarks were not discovered yet. But something is hidden in what we call the mass matrix, I thought. You know, a mixing matrix between K0 and K0bar. And there must be some strange things mixed in the matrix. But at that time, the third generation quark was not discovered. So, generally called the “superweak” theory, meaning the difference between eta+- and eta00 is small. They’re really small due to some second order effect of weak interaction. So, my experiment was to prove whether the difference is large or small.
And what did you find?
I found that it is small. The difference is less than 20 percent. But the big upshot at that time was, I was relatively slow, because I had little experience. And then Jim Cronin came up with a very brilliant idea, to measure the difference, much simpler than what I was preparing for. So, he measured a year before me, and one group at CERN also did a measurement later and “confirmed” Jim’s result. But there were errors in both experiments. But Jim Cronin’s experiment was carried out next to mine at Princeton-Penn Accelerator. I could watch how they measured. I knew the graduate students working under Jim. And Jim’s group came up with a large difference between eta+- and eta00. Mine was small, or the two eta’s came up almost the same value.
Jim used to pass by me and saying, “Oh, even if you’re wrong, still, your hard work deserves a Ph.D.” [laugh] But then, all of sudden, he found out that his graduate student didn’t do the right analysis, and some decays, Lambda decays, were misidentified as K0 decays. So, in a big presentation in Vienna, I made the presentation. Jim Cronin was supposed to give a presentation before me, and he said, “I’m sorry. Our results turned out to be wrong. So, please listen to Tune Kamae’s talk.” And so, he took back his PRL paper he had already published.
Tune, who was on your thesis committee?
I don’t remember. But my thesis was after Jim Cronin and company found out their analysis was faulty. So, there was not much discussion on my result. I think everybody believed that I did measured in a most—how you say—secure way to analyze it. I identified all pions coming out of K0. You know, it was all exclusive identification.
What did you learn from Jim Cronin in terms of how to do physics?
Oh, he’s very, very smart, and I admire him. Val Fitch was rather slow but very steady in thinking. He could not leave Princeton that much. But Jim was traveling everywhere. He went to carry on a neutrino experiment, as you know, in Fermilab. So, I learned a lot from Jim. I mean, Jim is a very smart and quick-thinking physicist.
What year did you complete your studies at Princeton? Was it 1968?
And what did you do next? What was available to you?
Yeah. I mean, because of that history I just told you, my experiment was very well advertised, I had an assistant professorship offered. But the University of Tokyo and Japan was asking funds to set up KEK, and there’s no younger generation of experimental physicists. So, I got a telephone call from Prof. Nishikawa and many others: they all told me to come back. So, I told Val that I think I will go back to Japan.
But you were open to possibilities of staying in the United States at that point.
You did not specifically want to go back to Japan.
Well, I wasn’t sure. But because of the—many of my fellow students, they were jealous of me because I had—I had given the invited talk at APS, and I had already an assistant professorship offered rather than a postdoc, but I decided to go back. And so, Val thought: “Oh, gosh. Yes, I support you.” [laugh]
And what was the initial appointment? Was it a faculty position or a postdoc?
Japan was like Europe. You don’t start with a faculty position right away. You start as a research associate, a “permanent position.”
And what group did you join when you got back to Japan?
Prof. Tetsuji Nishikawa. Nishikawa is an accelerator physicist who really began planning for an accelerator laboratory and eventually started KEK.
Tell me about the origins of KEK. How did it start?
During the war, there was an ambition led by Yoshio Nishina to build a big synchrocyclotron, like the one in LBL. But the plan was all crumbled, and cyclotron was banned in Japan after WWII. So, everyone hoped one day Japan will be able to build a big accelerator. So Japanese theory group proposed something like a 40 GeV machine, you know, something larger than what Brookhaven had, larger than what CERN had. They dreamed that Japan will be able to jump start to the forefront. But the government didn’t have money, and we could build only a small, 12 GeV.
Did you see KEK as unique or complementary, or in competition with accelerator programs elsewhere, such as in the United States and Europe.
Yeah. The funding took so long to come, so the first six, seven years, I worked in the small electron synchrotron the University of Tokyo had—something like the one Caltech had, a 1.3GeV electron synchrotron. But the works I did with the machine ended up being very important. For example, in the number of citations. One of the two work is adding sizeable citations now. I did two probably important experiments: one is in nuclear physics. Around that time Taylor and Friedman were doing deep inelastic electron scattering off the proton to discover the quarks. I did similar experiments on nuclei: deep inelastic in the nuclear level. High energy electrons knock off a proton out of a nucleus. And if you measure momenta of the final electron and the knocked-out proton, you can calculate how deeply the proton was bound in the nucleus. On the angular difference between the direction in which momentum was transferred from the scattered electron and the direction in which the knocked out proton came out, we can calculate the internal motion of the proton inside the nucleus. And that is a very, very clever way of measuring—assuming the independent particle model of nucleus, how deeply the proton was bound, and what state the proton was in, the S or the P state, or the D state.
That experiment is such a clean experiment, so this experiment established that the proton inside the nucleus does not go any deeper than 55 MeV. So, nuclear potential saturated around 55 MeV, at around the mass number of Ca40. We could see three distinct angular distributions, S-like distribution, P-like distribution, and D-like distribution at different binding energies. That was probably a world-class experiment for the small synchrotron. So, we got invited to Gordon Conference and others to give invited talks. And then a few years later, I started another experiment. There was a small experiment done at SLAC.
You remember the name, Bjorn Wiik, who was the director of DESY. And he spent one year—I didn’t know him at that time—who measured the polarization of the proton coming out of photo-dissociated deuteron with a small electron machine at SLAC. I mean, it’s not a 20 GeV machine, but before the 20 GeV machine was built. The polarization of the proton coming out of photo-dissociated deuteron, was rising very sharply. But the energy of the machine forced them to stop the experiment there. I was thinking hard what we could do with this small electron synchrotron in Tokyo. So, I thought I might continue the measurement to higher energy. And I measured, in 1975, and that really went well. The polarization became almost 90 to 100 percent: Polarization of 100 percent means there are two amplitudes equal in magnitude. The two wave functions are interfering or changing phase relative to each other, or one phase is rotating up to 90 degrees. That means, indirectly, there is a resonance. The polarization changing rapidly means a new large amplitude exits and its phase angle is rotating rapidly.
So, I did a follow-up experiment and carried thorough extensive phase-shift analysis. I declared: the deuteron has a pion-emitting excited state, at 2380MeV. And I was excited about the experimental result as well as our theoretical analysis. But these results have been long forgotten, because after the experiment, the electron cyclotron was decommissioned so that the money would be fed into KEK, and the Caltech machine was already gone, too. SLAC has moved upward in energy, and so has DESY. So I thought nobody will reconfirm my results.
Then, 30-some years later, in Europe, in Uppsala and Juelich, polarized proton machines were built, and they did what I did, in the reverse channel. Instead of measuring a proton coming out of dissociation, they hit a polarized proton onto a neutron target (or a deuteron target) and measured the final states, exclusively. They plotted what you call the Argand diagram, a variant of the phase shift analysis. And then, they discovered there is a sharp resonance at 2380MeV. And they didn’t know my paper, probably, at that time. But later, a few years later, they discovered there was a Phys Rev Letter paper written by us, and then they’d come up with, oh, gosh, exactly the same energy, isospin, and spin. But they added an important new contribution that the resonance has a narrow width, one half of what we thought 40 some years ago. And that is very important, although not much progress has been made since then. Stan Brodsky, you may know, at SLAC.
He and some other people had long thought of color string could be entangled, meaning a pair of delta delta could be bound tighter than typical nuclear states. A nucleus is a bound state of almost colorless protons and almost colorless neutrons in nuclei, so the binding is very soft. But they thought eventually there would be a color entangled state of six quarks, meaning it’s not easy to separate that state into two color neutral objects, because the color-string is so entangled. And then the binding could be very tight, or meaning resonance with this would be narrow. So, their interpretation, by Stan Brodsky and many others, it is probably the first evidence for the color entangled states — they call by a different name, “hidden color states.” What it means is the color string is tightly entangled, so it’s not easy to separate into two color neutral objects.
But anyhow, the experiment was done with the small electron machine. I was lucky: you don’t necessarily need a big machine. So at KEK, I mean, I did a series of experiments, search for such exotic resonances, like four quark state, S*. But the experiment at Brookhaven claiming discovery of S* turned out to be wrong. We disproved at KEK and so did an LBL group. experiments disproving false claims are hopeless. Nobody will cite them anymore after a few years. Right? [laugh]
Tune, in terms of your own research, were you working with any international collaborators, or was this primarily a Japanese effort for you?
At that time, they were entirely Japanese efforts. The future planning beyond the 12GeV proton machine had begun at KEK around 1976, and many possible scenarios were discussed. The electron positron collider was already running at SLAC and DESY. Many Japanese physicists thought it might be wise to build something different, like the ep collider. Eventually, DESY built an ep collider. But I thought then that, the ep collider would not produce anything exciting. That was my instinct. I mean, yeah, you can study probably a little of QCD, but not very exciting. So, I proposed we should go head-on competition with SLAC. And at that time, there was speculation the top quark may be below 30 GeV. So, we tried to build a 30 GeV collider with a provision to go back to BBbar collider. Then to prepare for that, I moved my group at Univ. of Tokyo to Bay Area. We joined the PEP4 experiment at the PEP ring in SLAC.
Now, you were at SLAC initially as a visiting scientist, or full time?
Visiting scientist, for four to five years.
And what years was this?
This is ’80 to ’86 or so. I mean, in the early years, I was full-time at LBL to assemble a hardware and establish a group there. I stayed not at SLAC, but rather in Berkeley. And then graduate students and postdocs continued to work with the Berkeley and SLAC contingents of PEP4. I began to commute between Bay Area and Tokyo, because of the teaching duty at University of Tokyo. We stayed around Bay Area, Berkeley and SLAC, until 1986.
And what group did you join initially when you got to SLAC?
PEP-4, TPC, Time Projection Chamber.
Who was leading PEP-4 at that point?
Nygren. David Nygren of Lawrence Berkeley Lab.
And what were some of the major goals of PEP-2 when you joined?
I mean, we couldn’t hope to discover the top -quark, because t-quark was already known to be heavier than the maximum energy of PEP. So, it was to measure the tail of Z so that we could determine Z peak, and also resonances containing the charm quark. We ended up discovering F-star, (now it’s called Ds-star). It’s a bound state of a charm quark and a S-quark. My group led the search within the PEP-4 collaboration.
And who were some of your closest collaborators on PEP-4 at SLAC?
The closest was—David Nygren’s more of the detector guy, so I think we worked almost among ourselves. And the one I came across became one very important person. He is Werner Hofmann from MPI-Heidelberg, Germany. He stayed for three years, became a leader of his collaboration. One more person I worked with was Henri Videau of Ecole Polytechnique. So, these two acquaintances really became very important when I was hired by SLAC to work on the gamma ray astronomy project, GLAST.
Did you stay there direct from your visiting position, or did you go back to Japan at some point?
I came back to Japan, and around that time when the supercollider project (SSC) was just starting. So, as soon as I got back to Japan, Roy Schwitter and company asked me to represent Japan in the supercollider effort. So, I stayed on the committee—the program advisors’ committee. And I must have some ambitious to continue on something like SSC. But I got so frustrated of the American way of doing science. [laugh]
[laugh] Americans are also frustrated by the American way of doing science sometimes.
What do you mean by that specifically, Tune? What was frustrating to you?
I was already, regarded as a key member of “controlling” the Japanese contribution to the Superconducting Super Collider, but I had no power in real.
SSC nor Japanese contribution to SSC. So, when Roy and his close friends became slowly super optimistic in many ways, I was proposing: don’t go beyond 14 TeV, which was the max energy that the ring can reach, at that time, with existing technology to make superconducting magnets. Brookhaven and Fermilab had already produced several magnets to reach 14TeV, and so was test magnets built by KEK. But then somebody came up—this is an optimistic American way. You can add new ideas like NbTi magnets which can bring the energy a little bit higher, maybe 20 TeV. Then theory people jumped onto this idea.
Theorists argued that 20 TeV is better than 14 TeV, and if you can accommodate in the same ring, even at a cost substantially higher and takes a few more years. I argued that it’s already running so late—I mean, we were already three or four years behind the schedule. You may know that Navy officers and other US government officers were monitoring the SSC management. They became suspicious of scientists’ ability to manage such a big enterprise. And there’s a tension between them and scientists. So I called up, Jim Cronin and Jerome Friedman and many other key leaders in the US HEP community. I did solicit them to persuade the leaders not to go overly ambitious. And then, the answer I got from Jim Cronin was very, very interesting. And still I remember it very clearly. “Tune, this is the United States. Roy is Roy. I shouldn’t control nor influence Roy.”
This was a lesson for you.
This still is. In a very good way. This is the way US is ran, even now. And Americans energize themselves on this kind of principle. Those at the forefront of SSC, a particle physics project, moved to the Internet industries. Some may be in Google, Facebook, all other new business. Take Elon Musk, for example, you will never be able to convince Elon Musk to do something or any other things. And that carried the energy of the US. So yes, I said, “Yeah,” and Jim said that something to fail is bound to fail.
This is not a necessarily Japanese cultural way of looking at things.
Right. Right. I thought, you know, so many young scientists were fired or had to find new jobs. There were hundreds of younger postdocs working on the Texas site, and it was so rough for them. All of a sudden, you have to find a new position. Some of them had left a tenured professorship to work for SSC. For example, gosh. [laugh] I keep forgetting names. The theoretician who was a couple years ahead of me in Princeton, and he left the SLAC position and moved to SSC, and now back to Carnegie Mellon.
Yeah, exactly. You know, a person like Fred Gilman. He had betted his prime time for SSC. Fred Gilman is very talented so that he was hired by Carnegie Mellon or probably many other universities. But anyhow, this is a very Japanese way of thinking. In Japan, I was considered as an American. [laugh] In the US, I was still a Japanese. This experience pushed me to X-ray astronomy. I was interested in building new instruments, and I was working in the silicon detector area Hamamatsu had been just beginning to venturing into silicon stripe detectors. And then I discovered that silicon strip detector can measure X-ray energy quite well. For particle physics, it’s 1 or 0, either the particle passed or not. Nobody had really measured the analog energy a particle had deposited. And I began to detect and measure X-ray energies with prototype detectors. I was amazed to find out that they can measure the ion 55 K-line, about 5.9keV, clearly separated from the noise. So, if you improve a little, it could become an excellent large area X-ray detector with position information.
Then I thought we can build inexpensive Compton telescopes. If you measure the energy deposited at two scattering or absorbed points, you can constrain the gamma-ray direction. You cannot trace back gamma rays otherwise. But if the energy deposited in the two successive scattering sites, you can reconstruct where the gamma ray came from. Not uniquely, but only to a ring. But if you accumulate many of these gammas, you can have a gamma-ray telescope. So, I thought this could be useful for medical imaging as well as astronomical imaging. So I took an international patent. Then Burt Richter called me one day, and told me that Bill Atwood and Peter Michelson and company, are thinking to build a follow-up of EGRET gamma-ray telescope using silicon detectors. The basic idea was with the silicon detector arrays, one can measure energy deposited in a shower well and would be very powerful telescope. So, would you like to join us?
I discussed with other Japanese colleagues and decided, yeah, we can contribute silicon detectors. And the ability to measure the analog way also turned out to be very important, in knowing whether gamma ray was Compton scattered knocked out an electron, or pair created. The created pair does not separate widely as to deposit energy in two separate strips. If we can measure the energy deposited, we would know the energy was that of two particles, two minimum-ionizing particles. And then, I formed a group and secured a modest funding much faster than any European collaborators. So, the collaboration started first between US and Japan.
Unfortunately, SLAC had no astrophysicists at that time. Nobody ever had strong connection with NASA X-ray community other than Peter Michelson on campus with the gamma ray community. SLAC had the philosophy typical of Burt Richter We excel world-wide, and so, we don’t need any help. [laugh] So, SLAC had almost no connection to astrophysics community in Europe. Neither Peter Michaelson was connected well to astrophysics branch of CNRS France or INFN Italy. Because I worked at CERN for a short while, and also had connection to Europeans while in Berkeley, I managed to find friends among leaders in Europe. So, I could contribute to form the international collaboration known then as GLAST. Burt Richter had a lot of friends everywhere and so did David Leith. But younger generation SLAC has much less connection.
And so, Burt hired me, strangely, from Japan [laugh] to strengthen collaboration with astrophysics and astro-particle physics community in Europe, France, Italy and Sweden. CNES—NASA’s counterpart in France—had signed up to be a part of the collaboration and to contribute a large fund. But told us one day that they didn’t have any money left. So, I have to fly to Paris and go around and convinced CNRS to allocate some fund and France to remain in the collaboration. I also flew to Osaka where an International HEP Conference was meeting and met with INFN leaders to convince a strong PISA group to join GLAST.
Tune, besides Burt, what was the overall reaction at SLAC about this gradual broader move into astrophysics?
I think probably Burt was 100% determine. David Leith supported the move. David himself still wanted to carry on the SLAC B-factory project. It was a collaboration with Italian. And Elliott Bloom was another key player. The move probably was right one, because there’s the LSST project following after Fermi-LAT. It a big involvement and probably bring very important contributions to cosmology. And the LCLS is the mainstream now. If SLAC had remained solely in particle physics, DoE would not have funded SLAC to the level we see now.
What was your perspective on this?
What perspective do you mean?
As these transitions were happening, and in the larger collaboration?
Yeah. I don’t know. There’s no real golden rule of guidance. You have to be flexible, and you have to broaden your interest. Eyes and ears have to be kept open to—may not be 360 degrees, but at least 120 [laugh] degrees or so. That way, we can live in the world where things are evolving so fast. I was little involved in ILC, International Linear Collider, but I don’t think Japanese government would ever have money to build one in Japan. Although it’s a very interesting proposal, ILC probably will not come forward. And you know, even at CERN, I don’t know what may happen after an upgrade or two of LHC. So, with the Covid-19, everybody now is focusing more on the medical sciences than the physical sciences.
And to me, because I’m already old, I think that I can contribute now to something like the one I described. There, even with my limited capacity, I could contribute significantly in inventing new ways of, for example, people who have lost visibility, or have some difficulty in receiving education, or have some learning disability. I am trying to mobilize the tactile sense, hearing sense, and limited cognitive ability through touching. Instead of pedagogical mathematics textbooks, you know, something not easy to follow, I may be able to propose a better math book. Right? There must be a better way of presenting math. I love to work on the computer. Many of the manipulations of — formula manipulations could be done by computer programs now. Wolfram has added a nice ability, and so is a public domain program, Sage. They can do so much now that even if you’re blind, you can manipulate equations. The US does much better in such areas than Japan. In Japan, not many technically capable people are helping the handicapped mobilizing new technical front. So, even with my very limited ability, I am appreciated and can get some government grant. So, I feel like I’m doing something.
Tune, I’m curious on that point, if one of your motivations was that earlier in your career, so much of your work was devoted to basic science, without any particular application, and that you wanted to do something that had more of a real-world effect, a positive effect, on people.
Yeah. I mean, my wife keeps asking me the same question. [laugh] But like many others, when you are young, you don’t—unless some other reason, like, your father lost eye-sight and you want to help him. Unless this kind of motivation comes close to you, you really like either strive for a gold medal in Olympic or whatever your ambition may be. But I accept that, because ambition expands your ability, which later you can use for social benefits or establish a relation with other parts of society.
What sensibilities, as an experimental particle physicist, do you bring to these other areas, in terms of helping the visually impaired through these computer programs?
Well, as a particle physicist I worry sometime that the smartest brains available in the world are going to the string theory. But yes, spend a few years with your full capacity to explore and dive into whatever you think you can solve. But after you think you have more or less exhausted your capability, rethink what you can contribute with your brain, what you have trained for. These abilities will be very useful for the society. You gather up yourself, your experience: they could be used for some other area.
Tune, I’d like to ask a broadly cultural question.
Coming from KEK to SLAC, and also your collaborations in Europe, what have you learned about different cultural approaches to large-scale physics experiments, where they take place in Japan versus the United States, versus Europe?
I don’t know how to answer. It’s not easy to answer. I think the difference is not that big anymore. But rather, I worry about Covid-19, and also the Japanese younger generation is heading more inward. My generation, Japan was so devastated by World War II, and there was no other choice but to go and work in the US. Whatever chances are given to me, grab them. Do what you can do, and impress, if possible, the world rather than restraining in your home country. That kind of mentality is slowly disappearing in Japan, unfortunately. China has a lot of, just like the 1950s in Japan, ambitious young people. But if the two countries lose the interaction, both nationals head more—how you say—inward.
After returning from SLAC, I still love interacting with Europeans, and I kept continuing flying balloons from the Swedish balloon base, Esrange, in northern Sweden. It is in collaboration with Per Carlson’s group and his successor, Mark Pearce at KTH, Royal Institute of Technology. It’s really fun, and because many younger Japanese followed me and began interacting with KTH scientists. After this work, Covid 19 are forcing us to turn more—how you say—inward. But I mean, still the US has a lot of exciting capabilities. US universities are still growing, but the Japanese universities are not necessarily that strong anymore.
Tune, a generational question: of course, one of the major narratives in American science was that after World War II and particularly after the launch of Sputnik, the American government supported basic science, and that support was central to so much fundamental discovery. Would you say that general narrative also holds true in Japan in the postwar era?
No. I mean, in Japan, we were not allowed to have any military power after WWII. So, more the motivation was scientific and technical things. Science and technology drove Japanese youngsters. Young, capable generation of scientists who had been so frustrated and misused during the war, or even before the war. So, their energy really accumulated and re-appeared as this after-war surge of Japanese scientists and engineers to international scene. Actually, it is amazing that, after Yukawa, you know, Japanese won probably the second most Nobel Prizes, next to the US. But that kind of surge is slowly dying out.
So, there’s a generation—how would you say—who was forced to work unwillingly for the military and not allowed to do any science. Even after the war, the nuclear physics and the accelerator development were banned by the US occupation army, despite all the US scientists’ petition not to do that to the Japanese scientists. So, all the negative things, how you say, built up the pressure, and the pressure build up within the generation of Japanese, which is probably 10 years older than me, down to 10 years younger than me. And then the pressure is, more or less, gone.
The US, historically, have received influx of scientists as well as labors from Europe. When I was at Princeton, Civil Rights movement was a big thing. Most of those who were mowing the lawn on the Princeton campus were Italian and Greek. And these people as well as European scientists accomplished their so-called American dreams, and they excelled in some area. The US has still capacity, but I don’t know whether you can keep running that way for ever. I mean, I see very brilliant kids from India working on Stanford campus in the computer-related area, and so are Chinese kids. But I see a very limited number of Japanese kids.
Tune, do you feel lucky that you came of age, scientifically, during a very exciting and foundational history in particle physics?
I think so. If particle physics is so important for the society, [laugh] yes. Otherwise, I might have, you know, very frustrated… [laugh] I think the US is still strangely—you may suffer from influx of many illegal immigrants, but their ambition and energy are key to burning the US engine to roll. And Japan should do something similar. I propose that we should invite a lot of Asian—they rather like to work in Japan than in US, because firstly, it is closer to their home. You know, the younger generation has to take care of the elderly generation now, especially in Asia. Number of kids per family is close to 1 in Japan—and now it’s also small in China, Korea, Philippines, Indonesia—so, they cannot stay a long distance away from the family for many years and desert their parents. In the old days, Asian families had six, seven kids. So, somebody else stayed around the parents. But China went to the one-kid policy, and even after the rule got relaxed, only two. Japanese voluntarily decreased the number of kids to be one or two. So, the chances that you have to take care of your elderly parent is almost 100 percent. In my generation, I had three brothers and one sister, and that was typical. But now, it’s only one or two.
My last PhD student at Stanford was from Hong Kong. He had an offer in the US, but he rather chose to get the position in Kyoto University, probably because he can readily fly back to Hong Kong in a few hours or so. Salary wise, he would have been better working in the States. He also likes less-competitive atmosphere of Japan. Strange, but that’s happening. So, if the entire family moved to the US, migrate to the US, that still is a choice. But bright kids, by himself or by herself, migrating to the US would not work as much as it did 30 years ago. So, Japan should become the US to Asians. Compared to the size of the US, Singapore to Japan is something like California to Washington, DC. [laugh] Right? But the Japanese government, unfortunately, does not see that way.
Tune, you were at SLAC during a very interesting time of its overall transformation from Pief Panofsky’s original vision to what it is today. I wonder, with that broad perspective, from your view, what has worked well for SLAC with this transformation, and what has been a challenge?
I think there will be some so-called casualties, but I think SLAC did relatively well. I mean, the linear collider worked as an intermediate step, but then moved into the electron X-ray laser, which probably will keep running for years. Burt Richter steered towards astrophysics. Probably, Fermi-LAT is reaching its goal, or in a few years, we have to close down. But LSST will take off. And that project probably will remain active for tens of years. The flexibility DOE has managed to acquire over years. In Japan, that flexibility is not easy to find. The charter of KEK was written by bureaucrats not to allow much flexibility. That kind of flexibility is very difficult to build into a system in Japan.
In Fermi-LAT, there have been a lot of negotiations between DOE and NASA. I think what worked well is that the US national labs are now attached to universities, like Stanford, or Fermilab to U of Chicago, so Brookhaven to the Ivy League schools. And that kind of collaboration is working very well in Germany, too. Institutes ran by Max Planck Gesellschaft are “attached” to universities except that DESY and some other big laboratories are independent. Nearly 100 MPIs stay very close to university campuses: Heidelberg, or Technical University of Munich, or other universities. And these close ties with universities keeps flexibility. You can work with graduate student as a sort of young labor force, in a good way. But if a national lab like Brookhaven tries to be completely independent and cut off their association with the Ivy League universities or Chicago or Stanford just to satisfy politicians and bureaucrats, that will create a real danger to the US science community.
Tune, for my last question of our excellent discussion, let’s look to the future and return to the original topic that we talked about, and that is your current commitment to developing these programs for the visually impaired. Best-case scenario, what will this technology look like, who will it help, and how?
Okay. That is a big question. In the US, it will have been a lot easier, but in Japan, bureaucrat likes narrowest definition. If I get funded for this one branch of assistive technology, then if a neighboring agency wanted to support me, the first agent will ask me return the fund before applying to another. The system will give me a hard time to expand. You have to choose either one or the other. But—how do you say—that way I’m continuing on in a small scale. I tried to collect small funds to do a little bigger project. But never as much as a US funding agent would grant me. I began to collect crowd funding of a hundred to thousand dollars level. In the US, there are many more multimillionaires and foundations who donate to your project. I don’t think I can keep working this way longer than five years. So, I’d like to leave a set of things that a small business can continue to reproduce on what I accomplish. Funding I expect is no more than a few hundred thousand dollars for three years. But that seems to give a very good practice ground if you limit yourself in borrowing information technology. I mean, if you’re running a car without any intervention, human intervention, such technology would be converted to enable blind people walk streets by themselves. Right?
The program is very challenging, but rewarding. In self-navigation area. I’m trying to test out not on the street, which is dangerous, but in a large park, some place like Central Park in New York City, or Golden Gate Park in San Francisco, where no or very few cars are running. Only cyclists are my problem. I’m developing a guiding system which you may be familiar with, a technology to kinematically track GPS wave—what’s called RTK—a variant of GPS. A single GPS would not give sufficient accuracy, but rather detecting the phase-differences between GPS signal you receive with that received a reference station. The regular GPS detector you use on phones count digitized pulses, but this Real-Time Kinetics, you can really locate yourself within one meter. So, I’m planning to make an affordable unit. A new chip is now available. It was developed by ETH, or called in German as, “ay, tay, ha,” or Swiss Federal Institute of Technology. And they made it commercially available—the chip allows to measure the phase difference between the reference station (a fixed antenna) and yourself (mobile antenna). So, there’s a lot of interesting technology, and my curiosity will be all fulfilled. [laugh]
Tune, on that point, I’d like to thank you. This has been a wonderful time I’ve had, spending this time interviewing you, and I’m so glad we were able to do this. Thank you so much.
It was a great, great honor, and thank you for spending time with me.