David N. Schwartz talks about his latest book, The Last Man Who Knew Everything: The Life and Times of Enrico Fermi, Father of the Nuclear Age (Basic Books).

Steve Mirsky:    Welcome to Scientific American Science Talk, posted on February 19, 2018. I'm Steve Mirsky. On this episode:

David Schwartz:         And once people realize that Fermi had been splitting the atom, it was Szilard who approached Fermi and said, "You know, you may be able to create a chain reaction by splitting the uranium atom by bombarding it with slow neutrons.

Mirsky:               That's David N. Schwartz. His latest book is, The Last Man Who Knew Everything: The Life and Times of Enrico Fermi, Father of the Nuclear Age. Schwartz has a doctorate in political science from MIT. His previous book was NATO's Nuclear Dilemmas. He grew up with physics spoken fluently in his home, as you'll hear. We spoke at his agent's office in Manhattan.

                           "The Last Man Who Knew Everything," this was something one of his graduate students said about him. What does that really mean about Fermi?

Schwartz:          Well, it means that he was probably the last person who could view physics as an integrated hull. He had this comprehensive knowledge of virtually every area of physics that was based on this incredible, fundamental foundation that he had developed when he was a kid and through graduate school. He knew so much about every different area of physics, from astrophysics to particle physics to condensed matter physics to quantum theory. He even did geo physics. I mean he really loved physics and did it all. He also was at adept at experiment as he was at theory and that's really unusual. There was really no one who was like that.

                           So, when people were saying to me he was the last man who knew everything, I think they were referring to both aspects of his career that he had made fundamental contributions across the field and also was equally adept at experiment and theory—a very unusual guy.

Mirsky:               Yeah. Your descriptions of him overseeing the building of the pile with which they would eventually make the first controlled nuclear reaction, I was trying to imagine Einstein – [laughs] it's funny. It's funny to even think about.

Schwartz:          Yes, it is.

Mirsky:               Overseeing a construction project.

Schwartz:          Well, most theorists would be unable to –

Mirsky:               Or Dirac. It's so unimaginable.

Schwartz:          Well, no, it's interesting you say that. Dirac, actually, had an engineering degree, so was familiar with equipment but didn't like using it. Then you have Pauli, who was so bad, that people used to joke that if the equipment was going bad, Pauli must be in the neighborhood.

Mirsky:               Right. You had that in the book.

Schwartz:          Einstein really never conducted and experiment in his life. He conducted experiments in his head and those were extraordinarily profound, mental gymnastics, mental exercises. But Fermi just loved getting his hands dirty. He just loved – if he couldn't find a piece of equipment, he would make it himself. He made all of his detectors himself when he was – early days in Rome, he made all the Geiger counters, all the detectors. He just loved that kind of stuff.

Mirsky:               It really is almost unheard of for somebody like that to do the kind of basic theoretical work that he did and was famous for.

Schwartz:          That's correct. That's correct. There's – I can't think of a single experimentalist who had the penchant for theory. I mean Rutherford was one of the greatest experimentalists of all time, maybe the greatest in the 20^th century. He hated theory. He used to scoff at it. Madam Curie, another one who used to scoff at theory. Most of these people, most of the experimentalists had very little patience for theory. But Fermi loved theory, too.

                           I mean, as I say, he viewed physics as an integrated hull. If it involved physics in any aspect, he wanted to know more about it. He had this amazing what I call a tenacious sense of curiosity.

Mirsky:               Let's back up because I could be wrong about this but I'm under the impression, when I was a kid in the late '60s, early '70s, Fermi was still one of the best-known physicists in the world. If you asked somebody to name a physicist, of course, they'd say Einstein. But if you asked them to name another physicist, you'd probably get Fermi. I think that Fermi had maybe been kind of forgotten by the masses in the last couple of decades, in part because he, unfortunately, died so young. We don't really play up the important role of the Italian physicists from that era as much as the American and the German physicists. So, for people who may be hearing this and have never even heard of Fermi or who only know that he was a physicist, who was Enrico Fermi?

Schwartz:          Well, you know, let me just say that this is exactly the reason why I wrote the book. It's because people have forgotten who he was. Who was Enrico Fermi? He was one of the most significant figures in physics in the 20^th century. His accomplishments include what we call Fermi Dirac Statistics, which is the first attempt to integrate quantum theory and statistical mechanics. All of condensed matter physics rests on Fermi Dirac Statistics, and a whole lot more besides. Anytime you're talking about fermions in the system, you have to address Fermi Dirac Statistics.

Mirsky:               That's a clue as to his importance. When you get a whole class of particles named after you, you must have been a pretty big deal.

Schwartz:          Exactly. The reason for that is because Dirac came up with the same idea about six months later. But to his great credit, he said that Fermi did it first and Fermi deserves the priority. He was the one who encouraged people to call particles with half-spin fermions. So, we owe Dirac a little bit of credit for that. So, there's that contribution.

                           The second great contribution is the theory of beta decay, which is an astonishing leap of imagination, because what he did was Fermi used Dirac's ideas about quantum fields to explain a completely different process from electromagnetic radiation, which is the way Dirac had originally thought of it. Now it turns out the two are very deeply related as we discovered later. But Fermi didn't know that at the time. He just wanted to figure out a way that he could explain the process by which electrons and neutrinos are emitted from the nucleus of an atom. He did that. That led to 30 or 40 years of really interesting research, both in theory and experiment—many, many Nobel Prizes.

                           Then, you have what I consider about an eight or ten-year period of neutron physics, which he started off with by bombarding elements with neutrinos – with neutrons, I'm sorry – to see if he could get them to turn radioactive. He proved not only could they turn radioactive, but if he slowed down the neutrons, they would intensify the radioactivity dramatically. That idea led to the series of experiments that Hahn and Meitner and Strassman did in Germany, which led to the discovery that Fermi had been splitting the atom.

                           Once people realized that Fermi had been splitting the atom, it was Szilard who approached Fermi and said, "You know, this may be the source of a chain reaction. You may be able to create a chain reaction by splitting the uranium atom by bombarding it with slow neutrons." Then you have the development of the first nuclear reactor in '42, the Chicago Pile. Then that plays a role in the development of the Manhattan Project overall. So, it's really a tremendously rich seam of research that he continued after the war. That was a major, major accomplishment of him.

                           So, you have these three major accomplishments. Then, after the war, he was one of the first people to use high-energy accelerators to explore the nucleus of the atom by bombarding it with pions. So, his scientific legacy is huge. I haven't touched 90 percent of all the other things that he did, which would be wonderful for sort of an average physics career. So, he just was incredibly important across a lot of different areas.

Mirsky:               You tell a story in the book about Freeman Dyson as a young professor in his 20s at Cornell taking the bus to Chicago to show Fermi his results and Fermi, correctly, and Dyson eventually realizes how important Fermi's rather critical judgement of him and his work was to Dyson's eventual successes.

Schwartz:          Yes. Well, Fermi was never nasty about things. But he was always very blunt. He felt that physics was sufficiently important, that you don't sort of beat around the bush. If something was right, he said, "That's right. That makes a lot of sense." If something was wrong, he would say, "No, no, no, that's wrong and here's why I think it's wrong." It didn't matter to him whether you had worked for a half an hour or for three years.

                           Dyson had worked for three years on these theoretical calculations about the pion nucleon interaction. He came to Fermi very proud because he realized he had come up with similar results that Fermi was getting off of the machine, off of the experiments. But that didn't matter to Fermi. Fermi looked at what he was doing and said, "No, that's not right." To Dyson's great credit, he looks back on that as a wonderful experience, a learning experience because if Fermi hadn't been so blunt, Dyson may have spent another couple of years going down blind alleys and really making a fool of himself. Instead, he was warned off this approach and Dyson was grateful.

Mirsky:               But in spite of Fermi's insistence that some things are right and some things just aren't right, he was also of the school of good enough is good enough.

Schwartz:          Yes. He said to his daughter in the context of – his daughter – he had been making some rather crude furniture in the home. Laura stormed away when she saw it. She thought it was –

Mirsky:               Laura is his wife?

Schwartz:          His wife, yeah. Thought it was terribly ugly. He turned to his daughter, Nella, who had been witnessing all this and said, "Never make anything more accurate than it needs to be." That was his attitude about science. He didn't – he wasn't looking for the last possible decimal place. An order of magnitude was just fine for him, depending on the problem. He was very interested in how neutrons reacted and was very careful about how he did those experiments and wanted to make them as accurate as he could, but when it came to – let me give you an example of the classic –

Mirsky:               The atomic bomb paper experiment?

Schwartz:          Yes, exactly.

Mirsky:               I was going to talk about –

Schwartz:          The Trinity blast takes place, the first atomic bomb blast. Fermi waits for the blast wave to hit. As it hits, he scatters strips of paper. He has calculated on the back of an envelope how far the strips of paper need to be moved to accord with different yields. So, he looks and says it's about two meters. So, it's about 20 kilotons. That's about right and that's all that you really needed to know. That was much quicker than the equipment that they had onsite because they had to sort of sit there and calibrate and review the records. It came to something like 16 or 17 kilotons or something like that. But 20 kilotons was just about right.

Mirsky:               He had a real talent for these kinds of back of the envelope calculations. You talk about this whole class of – it's not a mathematically rigorous class of problems but what wound up being called Fermi problems.

Schwartz:          Exactly and where you – the classic one is how many piano tuners are there in Chicago? That's the great one. Any kind of calculation that you do ends up with somewhere between 100 or 200, right?

Mirsky:               Right.

Schwartz:          Because you need to know what the approximate population of Chicago and how many households that turns into and how many households, generally, you think have pianos. Then, how many pianos can a piano tuner tune in a day? It's not 30 and it's not 1. It's got to be somewhere in between there. So, by process of estimation, you get to a number that's probably not that far off. That's the way Fermi loved to approach problems officially. Then, if he felt it was important to get more accurate, he'd dive in and get a little bit more accurate. But he wanted to know that he had the approximate answer very quickly.

Mirsky:               I remember at Cornell, a question that Feynman had allegedly posed that remind – the Fermi problems remind me of this. Maybe Feynman picked it up from Fermi or maybe Feynman had his own – because Feynman was also an original kind of thinker. But we were all asked, "If everybody in the world was put in Lake Cayuga, how high would the water level rise?" That seems like the same kind of problem.

Schwartz:          Yes, that's exactly the same kind of problem. You just have to figure out how many people are there in the world, what's the average mass of – what's the average volume of a person –

Mirsky:               And what's the size of Lake Cayuga?

                           [Crosstalk]

Schwartz:          What's the _____ of Lake Cayuga? If you get it wrong by a factor of two or three, that's fine. If you're wrong by a factor of 1,000, that's not good. But wrong by a factor of two or three, you're on the right track.

Mirsky:               Yeah, it's really interesting the way of thinking. Just to remind people, when Fermi is already a professor, the neutron hasn't even been discovered.

Schwartz:          That is correct.

Mirsky:               It's kind of mindboggling because we take so much for granted about our deep knowledge of atomic structure now that's available to us. But these people were in a dark room bumping around.

Schwartz:          Well, this is a point that I try to make in the book – I think I do – which is that this was a time of enormous ferment, the field of science. Fermi was very bright and very gifted and worked his butt off to be as good as he was. He really worked hard at it. But he was also very lucky in the sense that when he was born and the kind of problems that arose when he was a physicist when he was a young man – if he had been a physicist today, I don't know what – I don't know whether he would have been as successful. But I know that he grew up in a time when there was a tremendous amount to be discovered.

                           People didn't know about the neutron. People knew that the mass of a nucleus was much greater than its charge but they didn't know why. It was only in 1932 that the neutron was discovered. That opened up all of nuclear physics. People didn't know how to explain beta decay. People didn't know how to explain the different intensity of spectral lines.    

                           When you go through a spectroscope, they didn't know how to explain that. That was Heisenberg's great contribution. People didn't' know how to explain the Zeeman Effect, which is that spectral line split up when they're in a magnetic field. He sort of posited a fourth quantum number. So, there's all this wonderful ferment going on. Fermi was a part of that. He was very lucky to be born in the time and place that he was.

Mirsky:               That fourth quantum number, people may have heard of the Pauli Exclusion Principle. So, that's where that kind of overlaps.

Schwartz:          Exactly. The Exclusion Principle was Pauli's attempt to explain it. He said that no two electrons can share the same four quantum numbers. He didn't want to specify what that fourth quantum number was. He just said it had to have one of two values. It turned out that that was spin. Pauli, himself, sort of rejected the spin hypothesis for a while until he was persuaded otherwise. But in fact, Fermi used the Exclusion Principle for his statistics, as I explained earlier.

Mirsky:               Fermi was, also, not your stereotypical, reclusive, quiet physicist. He was very gregarious. He loved to go swimming and hiking and play tennis. He was very keen on keeping a regular schedule. If they were in the middle of an experiment, the results of which might change all of physics, he would still say, "No, it's time for lunch."

Schwartz:          Absolutely. He loved his lunches. He was a creature of habit. He did that twice. He did that famously twice. Once was with the slow neutron experiments and one was with the Chicago Pile when they both – both times they took a break for lunch. He was a very gregarious person, a very social person.

                           He loved small group physics. He didn't like to do physics on his own. He – well, let me put it another way. When he did physics on his own, it was between 5:00 and 7:00 every morning. He would get up at 5:00 in the morning, go to his den, and just do physics on his own from 5:00 till 7:00. Then he'd have breakfast. Out of the home by 8:00 and into his office or lab. Then it was with people all day long. All day long.

                           He loved working with people. The groups that he formed enjoyed being with him on the weekends as well because he would invite them out to Lake Michigan for a swim or up to the Italian Alps for a hike. They all got to know each other very, very well. He was very gregarious from that point of view.

Mirsky:               His entire education of himself and then the way he educated others is fascinating to me because it's anything but methodical and planned. When he was a kid, he would just picked up used books and he learned all of – I mean all of the available physics in the world that way. Then, when he was a young professor, there were set courses for the kids who were not going to be physicists. But the students who were going to be physicists, they basically just had seminars where they would get together and somebody would ask about something and he would launch – he had all this knowledge available in his brain.

Schwartz:          That's right.

Mirsky:               He would launch into a complete lecture about the particular field that anybody asked him about. Who learns like that? It seems like it's a great way to learn, but we don't learn like that anymore.

Schwartz:          Well, I think he was incapable of learning anything without teaching it himself. You see how he learned – when he was young and he was reading all those books, he had his friend, Persico, who he was able to teach. So, he was always teaching someone. He did have a mentor, a really great mentor, this fellow who was his father's colleague at the railway ministry, who structured his learning a little bit. Because Fermi wanted to be able to explain how a spinning top works from a physics point of view. It turns out to be that's a very complicated subject. There's a simple answer but then there's a very complicated answer and the more you study it, the more complicated it is.

                           This mentor of his said, "Listen, if you really want to understand that, you have to start from scratch. You need to know calculus. You need to know vector algebra. You need to know a whole lot of stuff. Then you need to understand classical mechanics." Basically, this was the coursework that his mentor led him through. But he loved – Fermi, himself, couldn't really process unless he was teaching.

                           So, his – a great example of that was when Dirac came out with his quantum electrodynamics. Fermi read it and was troubled because it uses some very arcane mathematics that was very difficult to understand. So, Fermi tried to recast it in his own language and he did that in a seminar setting with a group of five or six other students. They would sit and talk all – for a couple of hours every day until Fermi felt that he really had it down. Then he wrote a paper that really helped a lot of other people understand what Dirac was talking about.

                           So, yes, Fermi was very unusual from that point of view. I don't know whether others share that. I don't know enough about other physicists to know whether someone like Feynman or someone like Gell-Mann had the same compulsion to teach. I mean it was a compulsion. I mean it was – on Fermi's honeymoon, he tried to teach Laura, his wife, Maxwell's equations. I mean that's crazy. But he just had this compulsion to teach.

Mirsky:               Yeah, you can imagine that for Einstein teaching would've been torture.

Schwartz:          I'm not sure what – for Einstein perhaps, but certainly for Dirac. I mean Dirac just – it was painful. People would come away scratching their heads. There was one famous incident where someone was listening to a lecture from Dirac and he raised his hand and said, "Professor Dirac, there's something here I don't understand." There was silence.

Mirsky:               The silence went on for a while.

Schwartz:          For a long time. Dirac said, "Well, you haven't asked a question."

Mirsky:               So, he just stood there and didn't say anything.

Schwartz:          Didn't say anything.

Mirsky:               You begin the book by talking about why you wrote it, and that's a really interesting story, because you're not a physicist, although you must have been exposed to a lot of physics when you were sitting at the dinner table as a kid.

Schwartz:          Yes. My father was a particle physicist. While I never studied physics formally or I took physics for poets at Stanford, I was able to absorb an awful lot from my father. He was a very good teacher, himself. Whenever I had a question, he would sit down and make it very clear to me. I absorbed enough to be a competent lay person in the subject. That's what I want – that's the kind of person I wanted this book to appeal to. I wanted it to appeal to a lay person. I hope I got that right.

                           My father passed away in 2006 and in 2013 I was looking through some of his papers. There was this wonderful paper by a friend of his about Fermi's time in Chicago. It was about 20 pages. I read the thing and I thought, "What an interesting guy. Not only was his –" because I didn't know very much about him. Not only was he a great experimentalist and a theorist but he had all these phenomenal students, five of whom went on to win Nobel Prizes. I thought, "Let me get a biography of him. This is someone I want to learn more about." I was stunned that the last English language biography was Emilio Segre's in 1970. So, I decided I was going to do this and update it because I thought that it needed updating.

Mirsky:               You had to write the book that you wanted to read?

Schwartz:          That's exactly right. That is exactly right. There are some wonderful things about the Segre book, but there are some difficult things about the Segre book. There are some wonderful things about Laura Fermi's memoir of her marriage to Enrico. It's called Atoms in the Family. There are some wonderful passages in there. But there are some limitations as well. I thought that it was time to rectify that and to really produce something that gave a lay reader a whole picture of him, not just the physics but also – and not just the history, but also the person.

Mirsky:               Let's let the cat out of the bag. Your father was a really pretty good physicist. He shared the 1988 Nobel Prize in physics.

Schwartz:          Yes, he did.

Mirsky:               He had the opportunity to be Fermi's academic son by being his graduate student. But he passed that up. But eventually became Fermi's academic grandson because his mentor was –

Schwartz:          Was Jack Steinberger who was a graduate student.

Mirsky:               - who was a Fermi student.

Schwartz:          Yes. My father loved to tell this story that – because it's the callowness of youth, if you will. He came to Jack Steinberger at the end of his four years at Columbia as an undergraduate and said, "Jack, I'd like to stay at Columbia for graduate school and I'd like you to be my dissertation chairman." Jack said, "That's a terrible idea. You should never stay at the same place for graduate school that you did undergraduate work. You'd do much better with Enrico Fermi at Chicago." This was '53.

                           My father said, "But if I do that, I'll lose all the credits I have for all my graduate courses that I've taken here at Columbia." Jack sighed and said, "Oh, well, okay. If you're determined to keep those graduate credits, stay here and I'll be your chairman." He was. So, I think my father learned a lot of his experimental taste, if you will, from Steinberger who learned a lot of it from Fermi. I try to relate in the book, Steinberger really credits Fermi with being his greatest inspiration, the person who really made him the physicist that he became.

Mirsky:               I always like the track the genealogies, the academic genealogies, just like the concert pianists trace their lineages back to Beethoven or List. I knew a fellow whose biological father was his academic grandfather.

Schwartz:          Oh, my. That's great. But you know, in the academic world, in general – I don't know if it's still true but it was true when I got my degree – it is like a guild system. Your professor, your chairman of your PhD committee is really the person who gives you the degree. You become a student in every sense of that person. That person shapes the way you think about your field in a very profound way. My dissertation chairman was a guy named Bill Kaufmann up at MIT and he profoundly affected the way I viewed the world and the way I think about things. Everyone who worked with Fermi had that experience probably cubed because Fermi was such a spectacular teacher and such a profound intellect.

Mirsky:               Now you had never – you've written books before, but you'd never written a history book before.

Schwartz:          My NATO's Nuclear Dilemmas is a little bit of history, but this was really a new experience for me. I didn't have an opportunity in any of my other books to really do a deep dive into archives, to do a lot of really intensive interviews, to really go as deeply as I did in this book. It was really exciting. It was really exciting.

                           There's this moment where I went into the Fermi archives at Chicago, the first folder I opened had his passport. It had his driver's license. It had a little card that had the combination of his bicycle lock. It had his Atomic Energy Commission badge. I'm sitting here and I'm looking at this stuff and I'm thinking, "Oh, my god, this is a direct connection. I am holding the stuff that belonged to him."

                           You feel this incredible direct connection, which I think motivated me as a historian. I think the thing you have to guard against is hate geography because it's so easy to slip into that. I tried very hard to show both the bright side and the dark side of his life and the complexities about his life.

Mirsky:               Yeah. There were points you make that as a young man, he was kind of callous sometimes. He could be difficult because he would lord his incredible intellect over some people. But as he aged, he really mellowed and became a much nicer person.

Schwartz:          I think he became a much nicer person. He was also not the greatest father and not the greatest husband. Like many people of his time and era, if you were a professional, you devoted a lot of time to your career and you neglected your family. He did that in spades. He did that an awful lot. I think his kids suffered from it more than his wife.

                           I think his wife pretty much knew what she was buying into when she married him. They had been dating for a while. She knew how to give as good as she got, particularly when he was teasing her which he did mercilessly. He only teased people who he really loved. But he really teased her a lot. But I think his kids suffered a bit from the distance. He was closer to his students than he was to his kids. So, it's a complicated story about a complicated man.

Mirsky:               He was so focused on getting the controlled chain reaction to work that in some ways he actually gave his life. He gave many years of his life away because of the experimental methodology where they were exposed to these incredibly toxic materials.

Schwartz:          Exactly. I mean he was breathing in stuff all the time, but he was running down the corridors, both in Rome and at Columbia with highly radioactive samples, running from one room to another so that he could test the radioactivity with Geiger counters. We will never know whether that's what caused his cancer. There are arguments both ways. But I think it's – my own view is that it hastened his demise.

Mirsky:               Yeah. December 2, 2017 is the 75^th anniversary of that first successful, controlled chain reaction in human history.

Schwartz:          Yes, it is. It's a milestone. We're living with that legacy today with nuclear reactors, nuclear reactors, which had the promise of clean energy. That promise has been tainted by accidents and by our inability to figure out what to do with spent nuclear fuel. Then we have nuclear weapons, which there are now eight more countries that have nuclear weapons. I'm feeling luckier every day that they haven't been used.

                           I think that it's a dark legacy, with some bright spots. If anyone has had either diagnostic treatment or therapy with radioisotopes, they can thank Fermi because they're all made in nuclear reactors. Those radioisotopes are made with nuclear reactors. But there is a dark side of this as well.

Mirsky:               His work on producing neutrons is what makes all those kinds of therapies available.

Schwartz:          Exactly right. The other thing that I think is worth talking about a little bit is the contribution that immigrants played to all this. You know? It's quite possible the Manhattan Project would have succeeded without immigrants, but it certainly wouldn't have succeeded in the amount of time that it did and with the fewest of hiccups. You had this fellow, Enrico Fermi, who was an Italian national, who comes to the United States, fleeing fascist Italy in 1939 and he's working at the heart of this project that is top secret.

Mirsky:               So, imagine, he is a citizen of a country that we're at war with.

Schwartz:          He is an enemy alien in the heart of the Manhattan Project. There were no Germans involved at that time. He was the enemy alien in the heart of the Manhattan Project.

Mirsky:               They fled – his wife was Jewish and they realized it was time to get out. Her father stayed in Italy and he was eventually sent to a concentration camp and died.

Schwartz:          Yes. He felt that he was protected by his status as an admiral in the Italian Navy. In fact, while Mussolini was alive, he was protected. Mussolini passed this odd law that allowed Jewish families to opt out of the anti-Semitic laws that the Italian government passed. It was focused mainly on families who were very wealthy or very important and lent the regime prestige. So, if you were a Jewish family who was generally supportive of the fascist government – and there were some - you could opt out of the anti-Semitic laws.

                           Laura Fermi's father applied for exemption and got it for the whole family. But then, in 1943, Mussolini fell and the Nazi's took direct control over the City of Rome. He was finished. He was sent off to a concentration camp as were many Italian Jews.

Mirsky:               Primo Levi, a prominent example.

Schwartz:          Exactly. There were people in the United States who wondered whether Fermi should get a security clearance. They felt, "Well, you know, here's a guy who's changed loyalties once. Might he change it again?" Well, they conveniently forgot that much of what was classified in the Manhattan Project originated in Fermi's brain. So, fortunately, the FBI and the Army saw common sense and gave him the clearances. Otherwise, it would have been just stupid and he was able to continue.

                           Now, he became a naturalized U.S. citizen, I think, toward the end of '42. So, there was a period of time, a short period of time when he was a real enemy alien and then he naturalized. But he was very grateful to this country for giving him a home and for treating him the way they did, and for giving him the opportunities. He loved America. He did.

                           He loved hamburgers and Coca-Cola and baseball and he wanted people to call him a Hank because Enrico, in Italian, is the equivalent of Henry and he wanted to be known as an American. So, he wanted to be called Hank. No one called him Hank. But he loved America.

Mirsky:               By talking about this immigrant subject, are we – do you mean to bring it up in our current –

Schwartz:          Absolutely. I do believe that when we turn immigrants away, who knows what kind of talent we're turning away. Are we turning away the next Fermi? Are we turning away the next Von Neumann, who was a Hungarian refugee who did so much on the Manhattan Project and elsewhere? Are we turning away a Szilard? Are we turning away and Einstein? Immigrants have played an incredibly important role in our nation's story. This is one example where they played a very key role.

Mirsky:               We don't even necessarily need to talk about the real luminaries. I mean the science in the United States universities is performed by graduate students, for the most part, and post-docs who are taking orders from a mentor. A large percentage of them are from other countries. It used to be an inviting place for them to be to come here and many stayed. If they can – we're increasing the difficulty of them getting here and we're making it difficult for them to stay here.

Schwartz:          Yes, and I think that's tragic. I think we will suffer in ways that we can hardly imagine if this policy continues.

Mirsky:               That's it for this episode. Get your science news at our website, www.ScientificAmerican.com, where you can check out our special report on science at the Winter Olympics. There's a lot of physics going on in skiing, skating, and sliding. You can watch the physics more slowly in curling. Oh, by the way, if I remember right, we came up with an answer of about seven feet for how high Lake Cayuga would rise if you put everyone on earth in it, back in 1983, anyway.

                           Follow us on Twitter where you'll get a tweet whenever a new item hits the website. Our Twitter is @sciam. For Scientific American Science Talk, I'm Steve Mirsky. Thanks for clicking on us.

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