The von Neumann-Fuchs bomb, and the radiation compression mechanism of Ulam-Teller-Sakharov

Some useful references below on the Ulam-Teller mechanism, Sakharov's Third Idea, and the von Neumann-Fuchs thermonuclear design of 1946. They resolve a mystery discussed previously on this blog:

Sakharov's Third Idea: ... If Zeldovich was already familiar with radiation pressure as the tool for compression, via the Fuchs report of 1948, then perhaps one cannot really credit Teller so much for adding this ingredient to Ulam's idea of a staged device using a fission bomb to compress the thermonuclear fuel. Fuchs and von Neumann had already proposed (and patented!) radiation implosion years before. More here.

It turns out that the compression mechanism used in the von Neumann-Fuchs design (vN is the first author on the patent application; the design was realized in the Operation Greenhouse George nuclear test of 1951) is not that of Ulam-Teller or Sakharov. In vN-F the D-T mixture reaches thermal equilibrium with ionized BeO gas, leading to a pressure increase of ~10x. This is not the "cold compression" via focused radiation pressure used in the U-T / Sakharov designs. That was, apparently,  conceived independently by Ulam-Teller and Sakharov.

It is only recently that the vN-F design has become public -- first obtained by the Soviets via espionage (Fuchs), and finally declassified and published by the Russians! It seems that Zeldovich had access to this information, but not Sakharov.

American and Soviet H-bomb development programmes: historical background by G. Goncharov.

John von Neumann and Klaus Fuchs: an Unlikely Collaboration by Jeremy Bernstein. See also here for some clarifying commentary.


A great anecdote:

Jeremy Bernstein: When I was an undergraduate at Harvard he [vN] came to the university to give lectures on the computer and the brain. They were the best lectures I have ever heard on anything — like mental champagne. After one of them I found myself walking in Harvard Square and looked up to see von Neumann. Thinking, correctly as it happened, that it would be the only chance I would have to ask him a question, I asked, ‘‘Professor von Neumann, will the computer ever replace the human mathematician?’’ He studied me and then responded, ‘‘Sonny, don’t worry about it.’’

Note added from comments: I hope this clarifies things a bit.

The question of how the Soviets got to the U-T mechanism is especially mysterious. Sakharov himself (ostensibly the Soviet inventor) was puzzled until the end about what had really happened! He did not have access to the vN-F design that has been made public from the Russian side (~2000, after Sakharov's death in 1989; still classified in US). Zeldovich and only a few others had seen the Fuchs information, at a time when the main focus of the Russian program was not the H bomb. Sakharov could never be sure whether his suggestion for cold radiation compression sparked Zeldovich's interest because the latter *had seen the idea before* without fully comprehending it. Sakharov wondered about this until the end of his life (see below), but I think his surmise was not correct: we know now that vN-F did *not* come up with that idea in their 1946 design. I've been puzzled about this question myself for some time. IF the vN-F design had used radiation pressure for cold compression, why did Teller get so much credit for replacing neutrons with radiation pressure in Ulam's staged design (1951)? I stumbled across the (now public) vN-F design by accident just recently -- I was reading some biographical stuff about Zeldovich which touched upon these issues.

https://infoproc.blogspot.com/2012/10/sakharovs-third-idea.html

Consider the following words in Sakharov’s memoirs, with a note he added toward the end of life:

Now I think that the main idea of the H-bomb design developed by the Zeldovich group was based on intelligence information. However, I can’t prove this conjecture. It occurred to me quite recently, but at the time I just gave it no thought. (Note added July 1987. David Holloway writes in “Soviet Thermonuclear Development,” International Security 4:3 (1979/80), p. 193: “The Soviet Union had been informed by Klaus Fuchs of the studies of thermonuclear weapons at Los Alamos up to 1946. … His information would have been misleading rather than helpful, because the early ideas were later shown not to work.” Therefore my conjecture is confirmed!)

Another useful resource: Gennady Gorelik (BU science historian): The Paternity of the H-Bombs: Soviet-American Perspectives

Teller, 1952, August (re Bethe’s Memorandum): The main principle of radiation implosion was developed in connection with the thermonuclear program and was stated at a con­ference on the thermonuclear bomb, in the spring of 1946. Dr. Bethe did not attend this conference, but Dr. Fuchs did. [ Original development by vN? ]

It is difficult to argue to what extent an invention is accidental: most difficult for someone who did not make the invention himself. It appears to me that the idea was a relatively slight modification of ideas generally known in 1946. Essentially only two elements had to be added: to implode a bigger volume, and, to achieve greater compression by keeping the imploded material cool as long as possible.

The last part ("cool as long as possible") refers to the fundamental difference between the vN-Fuchs design and the U-T mechanism of cold radiation compression. The former assumes thermal equilibrium between ionized gas and radiation, while latter deliberately avoids it as long as possible.

Official Soviet History: On the making of the Soviet hydrogen (thermonuclear) bomb, Yu B Khariton et al 1996 Phys.-Usp. 39 185. Some details on the origin of the compression idea, followed by the use of radiation pressure (Zeldovich and Sakharov).

F > L > P > S

Andrei Sakharov with daughter, 1948.

Excerpts below from The World of Andrei Sakharov (link goes to full text) by Gennady Gorelik. See Out on the tail for a discussion of Landau's logarithmic ranking of physicists.

(p.159) Discussing Tamm’s desire that Landau be his official dissertation opponent in his Memoirs, he remarked that the latter “fortunately, refused; I would have felt very awkward because I realized the dissertation’s inadequacies.” Sakharov also talked about his failure in pure physics in the summer of 1947, and how Pomeranchuk (his dissertation opponent) did “a hatchet job” on the same problem, while Landau dealt with it “in an elegant and productive way.” This gave Sakharov the basis to humbly “formulate a system of inequalities: L > P > S” (L for Landau, P for Pomeranchuk, S for Sakharov).

... Sakharov for some reason came to the Institute of Physical Problems, where Landau headed up the Theoretical Department and a separate group doing research and calculations for “the Problem.”

After we finished discussing our work, Landau and I walked out into the Institute garden. This was the only time we talked without witnesses, heart-to-heart. He said: “I really don’t like all this.” (The context was nuclear weapons in general and his participation in this work in particular.)
“Why?” I asked somewhat naively.
“Too much fuss.”
Landau usually smiled a lot and easily, baring his large teeth, but this time he was sad, even mournful.

Landau on the Soviet nuclear weapons effort:

(p.190, quote from 1952-3) "One must use all one’s strength not to get involved in the thick of atomic work. But one has to be very careful refusing it . . . If it weren’t for Box Five [Jewish ethnicity], I would not be doing special [nuclear-weaponry] work, but pure science, in which I now lag behind. The special work gives me a certain amount of personal security. But it’s far from my serving 'for the good of the Homeland' ... I have been reduced to the level of a “scientist slave” and this defines it all."

... Zeldovich was close enough to Landau to know how he felt about this work. Zeldovich considered Landau his teacher, and it was on Landau’s recommendation that Zeldovich was elected Corresponding Member of the Academy of Sciences. However, in the early 1950s, Landau berated Zeldovich with the foulest possible language when the latter attempted to drag him more deeply into secret work in spite of his unwillingness.

On Sakharov and Zeldovich.  Gorelik interprets events surrounding the development of the Soviet H-bomb as I did in the earlier post: Sakharov's Third Idea.

(p.188) From an eyewitness: These two prominent theorists had very different “styles of thinking.” Sakharov was characterized by inventiveness and great profundity while Zeldovich by very quick thinking and high erudition. These scientists created an extraordinarily creative climate; the Institute [Installation] became orphaned after their departure at the end of the 1960s.

Another eyewitness recalls how interesting it was to follow the discussion of these outwardly opposite individuals: One was short in stature, bespectacled, rapid in his movements, and spoke clearly; the other was tall, languid, and spoke with a slight burr. But they were linked by sharp minds and enormous physical intuition. Mutual problems stimulated their thinking and they quickly grasped the crux of processes; hardly anyone managed to follow the course of their reasoning.

... Sakharov himself did not underestimate the heroism of what he had done. Twenty years later, when he received an invitation to come to the United States and lecture, his wife asked him what would interest him the most in America. By that time his imagination was already involved in cosmology and the physics of elementary particles, and he had an altogether different view of the government for which he had created thermonuclear weapons. However, he told his wife that he wanted very much to sit side by side with Ulam to compare the paths by which they had arrived at the same solution (it was in the 1970s, when the roles played by Ulam and Teller in creating the H-bomb were not clear).

Zeldovich admired Sakharov’s talent, treated him “extraordinarily carefully,” “timidly,” and said: “What am I? Now, Andrei, he’s something else!” According to another witness, Zeldovich said: “I can understand and take the measure of other physicists, but Andrei — he’s something else, something special."

Sakharov's third idea

We know that the decisive ideas for the first thermonuclear device came from Ulam and Teller. Did the great theorists Sakharov and Zeldovich (both names will be familiar to students of cosmology and particle physics) who created the Soviet H-bomb have the same ideas independently, or did they obtain them via espionage? The answer is still in dispute ...

Scientific American: ... There are no documents shedding light on this crucial period. There are only three fragments of oral history:

1. Sakharov’s close associate Yury Romanov says: “The Third Idea emerged in the spring of 1954. It began when Sakharov brought the theorists together and set forth his idea about the high coefficient of reflection of impulse radiation from the walls made of heavy material.”

2. An associate of Zeldovich, Viktor Adamskii, recollects that one day Zeldovich burst into his study and joyously exclaimed: “We should do it differently, we’ll release radiation from a spherical device!”

3. The most intriguing is the testimony of another associate of Zeldovich, Lev Feoktistov, who questioned the Soviet originality of the Third Idea. To him the Third Idea was too sudden to be truly indigenous. He says there were “neither drawings nor accurate data from the outside,” but that Sakharov and Zeldovich were bright and experienced enough to be enlightened by just a few words’ hint from a well-placed spy.

... My own reading of Sakharov’s writings suggests that he never had access to Fuchs’s report of 1948. Consider the following words in Sakharov’s memoirs, with a note he added toward the end of life:

Now I think that the main idea of the H-bomb design developed by the Zeldovich group was based on intelligence information. However, I can’t prove this conjecture. It occurred to me quite recently, but at the time I just gave it no thought. (Note added July 1987. David Holloway writes in “Soviet Thermonuclear Development,” International Security 4:3 (1979/80), p. 193: “The Soviet Union had been informed by Klaus Fuchs of the studies of thermonuclear weapons at Los Alamos up to 1946. … His information would have been misleading rather than helpful, because the early ideas were later shown not to work.” Therefore my conjecture is confirmed!)

I think the following happened. In January 1954, Sakharov was thinking about how to realize the idea of atomic compression. By May, he had realized that the flash of light from an exploding A-bomb — as opposed to the neutrons and other material products — would be the best tool to compress the thermonuclear charge. He realized that the flash of light could be confined within a metal casing for a microsecond or so, long enough to compress the charge symmetrically. He discussed this idea with Zeldovich, who recognized this as the idea he had failed to appreciate in Fuchs’s report six years earlier. As soon as he grasped Sakharov’s arguments, he (with his close associate Trutnev) brought in some details from Fuchs’s report, but never mentioned the actual report to Sakharov, since the latter was not granted access to it. So, Sakharov drew the conclusion that Zeldovich and Trutnev had also been very close to the Third Idea.

If Zeldovich was already familiar with radiation pressure as the tool for compression, via the Fuchs report of 1948, then perhaps one cannot really credit Teller so much for adding this ingredient to Ulam's idea of a staged device using a fission bomb to compress the thermonuclear fuel. Fuchs and von Neumann had already proposed (and patented!) radiation implosion years before.

Technically Sweet

Regular readers will know that I've been interested in the so-called Teller-Ulam mechanism used in thermonuclear bombs. Recently I read Kenneth Ford's memoir Building the H Bomb: A Personal History. Ford was a student of John Wheeler, who brought him to Los Alamos to work on the H-bomb project. This led me to look again at Richard Rhodes's Dark Sun: The Making of Hydrogen Bomb. There is quite a lot of interesting material in these two books on the specific contributions of Ulam and Teller, and whether the Soviets came up with the idea themselves, or had help from spycraft. See also Sakharov's Third Idea and F > L > P > S.

The power of a megaton device is described below by a witness to the Soviet test.

The Soviet Union tested a two-stage, lithium-deuteride-fueled thermonuclear device on November 22, 1955, dropping it from a Tu-16 bomber to minimize fallout. It yielded 1.6 megatons, a yield deliberately reduced for the Semipalatinsk test from its design yield of 3 MT. According to Yuri Romanov, Andrei Sakharov and Yakov Zeldovich worked out the Teller-Ulam configuration in conversations together in early spring 1954, independently of the US development. “I recall how Andrei Dmitrievich gathered the young associates in his tiny office,” Romanov writes, “… and began talking about the amazing ability of materials with a high atomic number to be an excellent reflector of high-intensity, short-pulse radiation.” ...

Victor Adamsky remembers the shock wave from the new thermonuclear racing across the steppe toward the observers. “It was a front of moving air that you could see that differed in quality from the air before and after. It came, it was really terrible; the grass was covered with frost and the moving front thawed it, you felt it melting as it approached you.” Igor Kurchatov walked in to ground zero with Yuli Khariton after the test and was horrified to see the earth cratered even though the bomb had detonated above ten thousand feet. “That was such a terrible, monstrous sight,” he told Anatoli Alexandrov when he returned to Moscow. “That weapon must not be allowed ever to be used.”

The Teller-Ulam design uses radiation pressure (reflected photons) from a spherical fission bomb to compress the thermonuclear fuel. The design is (to quote Oppenheimer) "technically sweet" -- a glance at the diagram below should convince anyone who understands geometrical optics!

In discussions of human genetic engineering (clearly a potentially dangerous future technology), the analogy with nuclear weapons sometimes arises: what role do moral issues play in the development of new technologies with the potential to affect the future of humanity? In my opinion, genetic engineering of humans carries nothing like the existential risk of arsenals of Teller-Ulam devices. Genomic consequences will play out over long (generational) timescales, leaving room for us to assess outcomes and adapt accordingly. (In comparison, genetic modification of viruses, which could lead to pandemics, seems much more dangerous.)

It is my judgment in these things that when you see something that is technically sweet, you go ahead and do it and you argue about what to do about it only after you have had your technical success. -- Oppenheimer on the Teller-Ulam design for the H-bomb.

What is technically sweet about genomics? (1) the approximate additivity (linearity) of the genetic architecture of key traits such as human intelligence (2) the huge amounts of extant variance in the human population, enabling large improvements (3) matrices of human genomes are good compressed sensors, and one can estimate how much data is required to "solve" the genetic architecture of complex traits. See, e.g., Genius (Nautilus Magazine) and Genetic architecture and predictive modeling of quantitative traits.

More excerpts from Dark Sun below.

Enthusiasts of trans-generational epigenetics would do well to remember the danger of cognitive bias and the lesson of Lysenko. Marxian notions of heredity are dangerous because, although scientifically incorrect, they appeal to our egalitarian desires.

A commission arrived in Sarov one day to make sure everyone agreed with Soviet agronomist Trofim Lysenko's Marxian notions of heredity, which Stalin had endorsed. Sakharov expressed his belief in Mendelian genetics instead. The commission let the heresy pass, he writes, because of his “position and reputation at the Installation,” but the outspoken experimentalist Lev Altshuler, who similarly repudiated Lysenko, did not fare so well ...

The transmission of crucial memes from Szilard to Sakharov, across the Iron Curtain.

Andrei Sakharov stopped by Victor Adamsky's office at Sarov one day in 1961 to show him a story. It was Leo Szilard's short fiction “My Trial as a War Criminal,” one chapter of his book The Voice of the Dolphins, published that year in the US. “I'm not strong in English,” Adamsky says, “but I tried to read it through. A number of us discussed it. It was about a war between the USSR and the USA, a very devastating one, which brought victory to the USSR. Szilard and a number of other physicists are put under arrest and then face the court as war criminals for having created weapons of mass destruction. Neither they nor their lawyers could make up a cogent proof of their innocence. We were amazed by this paradox. You can't get away from the fact that we were developing weapons of mass destruction. We thought it was necessary. Such was our inner conviction. But still the moral aspect of it would not let Andrei Dmitrievich and some of us live in peace.” So the visionary Hungarian physicist Leo Szilard, who first conceived of a nuclear chain reaction crossing a London street on a gray Depression morning in 1933, delivered a note in a bottle to a secret Soviet laboratory that contributed to Andrei Sakharov's courageous work of protest that helped bring the US-Soviet nuclear arms race to an end.

Landau, Sakharov, and thermonuclear instabilities

Above, Lev Landau. See also F > L > P > S and Out on the Tail.

An incredible story from The World of Andrei Sakharov:

... Nonetheless, in the early 1950s, Landau worked on Sakharov’s assignments. True enough, that work was in computational mathematics, not theoretical physics. Odd “material evidence” of this appears in Landau’s Collected Works: placed between the 1958 article about fermions and the 1959 article about quantum field theory is the lecture “Numerical Methods of an Integration of Partial Equations by a Method of Grids.” It was published in 1958 but, as it indicates, describes the methods developed in 1951–1952.

When you look at the article’s unexciting formulas, it’s difficult to imagine what’s behind them. What’s behind them, among other things, is the first thermonuclear bomb in the world and the suicide of the head of the security department. ...

Landau’s group did the calculations for the 1949 A-bomb, for which he received an Order of Lenin and a Stalin Prize of the Second Degree.

Landau’s contribution to the hydrogen bomb was even greater, judging by the fact that he was awarded the title of Hero of Socialist Labor and a Stalin Prize of the First Degree. Landau’s group managed to complete the Sloyka calculations “by hand”; it was the problem akin to the one the Americans postponed until computers appeared. This required devising an entirely new method of calculation.

The processes of a thermonuclear explosion are much more complicated than an atomic one, if only because it includes the atomic one as its first step. Numerical calculations using old methods would have taken years, but the problem had to be solved in months, which ensured a new method needed to be found. However, while developing it at the Institute for Physical Problems, theorists found a serious mathematical problem—the stability of the calculations. Without solving it, they couldn’t be sure that the calculations, no matter how precise, would actually have any relationship to physical reality. The new method solved this problem. But the mathematics group directed by Andrei Tikhonov, which had been created in parallel as a failsafe, denied the problem’s very existence.

Dissent and discussion are common in science, but in this case the science was top secret and super-urgent. Beria could not wait for the problem to be resolved in a free exchange of ideas, so a meeting was convened under the chairmanship of Mstislav Keldysh, the future president of the Academy of Sciences. It lasted for several days and the discussions ended in an unusual way: based on Keldysh’s opinion, the top leadership gave the order regarding which interpretation was to be considered scientific truth—the top leadership was Nikolai Pavlov, the KGB general in charge of nuclear weapons development. And Tikhonov’s group switched to the new method of calculation.

The assignment for the Sloyka calculations sent to the Landau group was “a piece of graph paper, handwritten on both sides in green-blue ink, and it contained all the geometry and data of the first hydrogen bomb.”

[[ Sloyka = "layer cake" = early thermonuclear bomb design. ]]

This was possibly the most secret document in the Soviet project—and it could not be entrusted to any typist. After a mathematical assignment was prepared on the basis of this document at the Institute of Physical Problems, it was sent on to the Institute of Applied Mathematics where Tikhonov’s group worked. And the page disappeared there. Perhaps it was mistaken for a rough draft—it was a single handwritten page—and it was destroyed along with other drafts. But this action was not recorded, which is what led to the tragedy Sakharov describes:

The head of the Security Department from the Ministry—a man whose mere physical appearance, his stare from under drooping eyelids, elicited physical dread in me—came to investigate the extraordinary incident. Former head of Leningrad State Security during the so-called “Leningrad Affair,” when about 700 top leaders were executed there, he spent nearly an hour on Saturday with the head of Institute Security. The Institute official spent the next day, Sunday, with his family; they say he was cheerful and very affectionate with his children. He came to work on Monday 15 minutes early and shot himself before his co-workers arrived.

Andrei Sakharov with daughter, 1948.

Physicists can do stuff.

Orwell: 1944, 1984, and Today

George Orwell 1944 Letter foreshadows 1984, and today:

... Already history has in a sense ceased to exist, i.e. there is no such thing as a history of our own times which could be universally accepted, and the exact sciences are endangered as soon as military necessity ceases to keep people up to the mark. Hitler can say that the Jews started the war, and if he survives that will become official history. He can’t say that two and two are five, because for the purposes of, say, ballistics they have to make four. But if the sort of world that I am afraid of arrives, a world of two or three great superstates which are unable to conquer one another, two and two could become five if the fuhrer wished it. That, so far as I can see, is the direction in which we are actually moving ... 

... intellectuals are more totalitarian in outlook than the common people. On the whole the English intelligentsia have opposed Hitler, but only at the price of accepting Stalin. Most of them are perfectly ready for dictatorial methods, secret police, systematic falsification of history etc. so long as they feel that it is on ‘our’ side.

I am sure any reader can provide examples of the following from the "news" or academia or even from a national lab:

there is no such thing as a history of our own times which could be universally accepted  

the exact sciences are endangered  

two and two could become five

dictatorial methods ... systematic falsification of history etc. so long as they feel that it is on ‘our’ side.

Of course, there is nothing new under the sun. It takes only a generation for costly lessons to be entirely forgotten...

Wikipedia: Trofim Denisovich Lysenko ...Soviet agronomist and biologist. Lysenko was a strong proponent of soft inheritance and rejected Mendelian genetics in favor of pseudoscientific ideas termed Lysenkoism.[1][2] In 1940, Lysenko became director of the Institute of Genetics within the USSR's Academy of Sciences, and he used his political influence and power to suppress dissenting opinions and discredit, marginalize, and imprison his critics, elevating his anti-Mendelian theories to state-sanctioned doctrine. 

Soviet scientists who refused to renounce genetics were dismissed from their posts and left destitute. Hundreds if not thousands of others were imprisoned. Several were sentenced to death as enemies of the state, including the botanist Nikolai Vavilov. Scientific dissent from Lysenko's theories of environmentally acquired inheritance was formally outlawed in the Soviet Union in 1948. As a result of Lysenkoism and forced collectivization, 15-30 million Soviet and Chinese citizens starved to death in the Holodomor and the Great Chinese Famine. ...

 

In 1964, physicist Andrei Sakharov spoke out against Lysenko in the General Assembly of the Academy of Sciences of the USSR: "He is responsible for the shameful backwardness of Soviet biology and of genetics in particular, for the dissemination of pseudo-scientific views, for adventurism, for the degradation of learning, and for the defamation, firing, arrest, even death, of many genuine scientists."

Goldman v. Aleynikov

Michael Lewis on the Aleynikov-Goldman HFT matter. The article mentions that Goldman trailed other players like Citadel when Aleynikov was hired. The head of HFT at Citadel was (I believe) a contemporary of mine in grad school at Berkeley, who did his dissertation in string theory. Malyshev, the guy who hired Aleynikov from Goldman, had his own legal problems when he left Citadel.

Vanity Fair: ... Serge knew nothing about Wall Street. The headhunter sent him a bunch of books about writing software on Wall Street, plus a primer on how to make it through a Wall Street job interview, and told him he could make a lot more than the $220,000 a year he was making at the telecom. Serge felt flattered, and liked the headhunter, but he read the books and decided Wall Street wasn’t for him. He enjoyed the technical challenges at the giant telecom and didn’t really feel the need to earn more money. A year later the headhunter called him again. By 2007, IDT was in financial trouble. His wife, Elina, was carrying their third child, and they would need to buy a bigger house. Serge agreed to interview with the Wall Street firm that especially wanted to meet him: Goldman Sachs.

... And then Wall Street called. Goldman Sachs put Serge through a series of telephone interviews, then brought him in for a long day of face-to-face interviews. These he found extremely tense, even a bit weird. “I was not used to seeing people put so much energy into evaluating other people,” he said. One after another, a dozen Goldman employees tried to stump him with brainteasers, computer puzzles, math problems, and even some light physics. It must have become clear to Goldman (as it was to Serge) that he knew more about most of the things he was being asked than did his interviewers. At the end of the first day, Goldman invited him back for a second day. He went home and thought it over: he wasn’t all that sure he wanted to work at Goldman Sachs. “But the next morning I had a competitive feeling,” he says. “I should conclude it and try to pass it because it’s a big challenge.”

... He returned for another round of Goldman’s grilling, which ended in the office of one of the high-frequency traders, another Russian, named Alexander Davidovich. A managing director, he had just two final questions for Serge, both designed to test his ability to solve problems.

The first: Is 3,599 a prime number?

Serge quickly saw there was something strange about 3,599: it was very close to 3,600. He jotted down the following equations: 3599 = (3600 – 1) = (602 – 12) = (60 – 1) (60 + 1) = 59 times 61. Not a prime number.

The problem wasn’t that difficult, but, as he put it, “it was harder to solve the problem when you are anticipated to solve it quickly.” It might have taken him as long as two minutes to finish. The second question the Goldman managing director asked him was more involved—and involving. He described for Serge a room, a rectangular box, and gave him its three dimensions. “He says there is a spider on the floor and gives me its coordinates. There is also a fly on the ceiling, and he gives me its coordinates as well. Then he asked the question: Calculate the shortest distance the spider can take to reach the fly.” The spider can’t fly or swing; it can only walk on surfaces. The shortest path between two points was a straight line, and so, Serge figured, it was a matter of unfolding the box, turning a three-dimensional object into a one-dimensional surface, then using the Pythagorean theorem to calculate the distances. It took him several minutes to work it all out; when he was done, Davidovich offered him a job at Goldman Sachs. His starting salary plus bonus came to $270,000.

... One small example of the kind of problems Serge found: Goldman’s trading on the NASDAQ exchange. Goldman owned the lone (unmarked) building directly across the street from NASDAQ in Carteret, New Jersey. The building housed Goldman’s dark pool. When Serge arrived, 40,000 messages per second were flying back and forth between computers inside the two buildings. Proximity, he assumed, must offer Goldman Sachs some advantage—after all, why else buy the only building anywhere near the exchange? But when he looked into it he found that, to cross the street from Goldman to NASDAQ, a signal took five milliseconds, or nearly as much time as it took a signal to travel on the fastest network from Chicago to New York. “The theoretical limit [of sending a signal] from Chicago to New York is something like seven milliseconds,” says Serge. “Everything more than that is the friction caused by man.” The friction could be caused by physical distance—say, if the signal moving across the street in Carteret, New Jersey, traveled in something less direct than a straight line. It could be caused by computer hardware. (The top high-frequency-trading firms chuck out their old gear and buy new stuff every few months.) But it could also be caused by slow, clunky software—and that was Goldman’s problem. Their high-frequency-trading platform was designed, in typical Goldman style, as a centralized hub-and-spoke system. Every signal sent was required to pass through the mother ship in Manhattan before it went back out into the marketplace. “But the latency [the five milliseconds] wasn’t mainly due to the physical distance,” says Serge. “It was because the traffic was going through layers and layers of corporate switching equipment.” ...

In this last paragraph Aleynikov sounds more like Sakharov than a millionaire quant ;-)

“If the incarceration experience doesn’t break your spirit, it changes you in a way that you lose many fears. You begin to realize that your life is not ruled by your ego and ambition and that it can end any day at any time. So why worry? You learn that, just like on the street, there is life in prison, and random people get there based on the jeopardy of the system. The prisons are filled with people who crossed the law, as well as by those who were incidentally and circumstantially picked and crushed by somebody else’s agenda. On the other hand, as a vivid benefit, you become very much independent of material property and learn to appreciate very simple pleasures in life such as the sunlight and morning breeze.”

Brainpower Matters: The French H-Bomb

Michel Carayol, father of the French H-Bomb.

The article below illuminates several mysteries concerning the French development of thermonuclear weapons. Why did it take so long? Did the French really need help from the British? Who had the crucial idea of radiation compression?

The original inventors were Ulam and Teller. In the USSR it was Sakharov. The PRC inventor was Yu Min (see Note Added at bottom).

Without men such as these, how long would it have taken to develop breakthrough technologies that defined the modern age?

See also Les Grandes Ecoles, One hundred thousand brains, and Quantum GDP.

THE REAL STORY BEHIND THE MAKING OF THE FRENCH HYDROGEN BOMB

Nonproliferation Review 15:2 353, DOI 10.1080/10736700802117361

Based on the first-person account of coauthor Pierre Billaud, a prominent French participant, this article describes for the first time in such detail the history of the development of the French hydrogen bomb in the 1960s and the organization of military nuclear research in France. ...

On November 1, 1952, the United States conducted its first thermonuclear test, ‘‘Ivy Mike,’’ seven years and three and a half months after its Trinity test. It took the Soviet Union four years (August 29, 1949 -- August 12, 1953) and the United Kingdom four years and seven months (October 3, 1952 -- May 15, 1957) to achieve thermonuclear capacity. And in the following decade, China did it, with its sixth test, in fewer than three years (October 16, 1964 -- June 17, 1967). Yet after Gerboise Bleue it took France eight and a half years to reach the same landmark, detonating its first thermonuclear device on August 24, 1968. Why such a long delay, especially since the French were pioneers in nuclear research?

1965: What We Knew About the Technical Aspects

From 1955 to 1960, as we prepared for the first French atomic test, we were also pondering thermonuclear weapons. But the prospect of hydrogen weapons seemed so far into the future that we did not work seriously on it. ... Li6D was commonly considered the best fuel for thermonuclear weapons, but we did not have any idea about how to burn it. All the problems with the thermonuclear bomb can be summarized by this question: how to discover the process that will allow the Li6D to undergo a fusion reaction?

... Compared to our American colleagues in 1948, French scientists had many advantages: we knew that hydrogen bombs existed and worked and that they used Li6D, and we understood the reactions at work. We also had powerful computers, of U.S. origin, which were not available in the late 1940s. And we knew, more or less, the dimensions and weights of the nuclear weapons deployed at NATO bases in Europe and their yields. ...

De Gaulle: It’s taking forever! ... I want the first experiment to take place before I leave! Do you hear me? It’s of capital importance. Of the five nuclear powers, are we going to be the only one which hasn’t made it to the thermonuclear level? Are we going to let the Chinese get ahead of us? If we do not succeed while I am still here, we shall never make it! My successors, from whatever side, will not dare to go against the protests of the Anglo-Saxons, the communists, the old spinsters and the Church. And we shall not open the gate. But if a first explosion happens, my successors will not dare to stop halfway into the development of these weapons.


... In January 1967, I published a voluminous report wherein I presented and developed my idea from late 1965, left idle since, explaining why the current studies were going in the wrong direction and producing a ridiculously low thermonuclear efficiency. I proposed a scheme with two consecutive steps: a cold Li6D compression increasing the density, from the normal value of 0.8 g/cm3, by a factor of at least 20, followed by a sufficient temperature increase (the ignition). In this report, I also gave orders of magnitude of the energies involved in each step... [[ One can make the (flawed) analogy of Billaud to Ulam (multi-stage insight, but no mechanism for compression), and Carayol to Teller (proposed the right mechanism for compression, although in Teller's case he may have learned of it from von Neumann and Fuchs!!!). ]] 

In early April 1967, Carayol had the idea that the x-rays emitted from the fission explosion could transport the fission energy to the thermonuclear fuel chamber to induce the necessary compression. He published a brief paper wherein he presented, and justified mathematically, his architectural idea. This was the key to the solution for an efficient thermonuclear explosive device, consistent with the current data about U.S. hydrogen weapons. Carayol had rediscovered the radiative coupling concept first introduced by Americans Stanislaw Ulam and Edward Teller in January 1951.

Michel Carayol, the Genuine Father of the French H-Bomb

Michel Carayol was born in 1934 and died in 2003. His father was an industrialist and his mother a teacher. He entered Ecole Polytechnique in 1954, graduated in 1956, and joined the Armament. In 1962, he was part of the DEFA assigned to CEA-DAM at Limeil. In 1967, Carayol was part of the advanced studies branch.

... Soon after, in April 1967, Carayol wrote a brief report describing his proposal for a cylindrico-spherical case in dense metal, containing a fission device on one side and a thermonuclear sphere on the other. The report showed that the photons radiated by the primary *still very hot* in the X-ray frequency range, swept into the chamber rapidly enough to surround completely the thermonuclear sphere before the metal case would be vaporized. Carayol had discovered independently a scheme equivalent to the concept developed by Ulam and Teller in the 50s.

But Carayol's insight was ignored! It was British assistance that alerted project leadership to the value of Carayol's ideas. It is not enough for some isolated genius to make a breakthrough -- the people in charge have to understand its value.

... During the first months of 1967, Viard had told me, ‘‘A British physicist is showing some interest in what we do.’’ At several embassy parties, a first-rate British atomic scientist, Sir William Cook, former director during the 1950s of thermonuclear research at Aldermaston, the British center for atomic military applications, had approached the military attache´ at the French Embassy in London, Andre´ Thoulouze, an Air Force colonel, and had hinted to our nuclear research program. Thoulouze had previously been in charge of an air force base and knew Rene´ David, who would later work at the DAM. For this reason, instead of contacting the French main intelligence services, Thoulouze directly contacted our information bureau at CEA, the BRIS, where David was working at the time. In analyzing the fallout from the French tests, the Americans, the British, and the Soviets knew that we had not made any real progress on the thermonuclear path. In 1966 and 1967 we had tested some combination of fission with light elements. Cook told Thoulouze that we had to look for something simpler.

Two weeks after the Valduc seminar, on September 19, and while the work resulting from the Valduc decisions had not yet concretely gotten under way, Thoulouze came from London bearing information from this qualified source. Jacques Robert immediately convened a meeting, in the DAM’s headquarters in Paris, to debrief this information. Only three other people attended the meeting: Viard, Bonnet (DAM’s deputy), and Henri Coleau (head of the BRIS). The information, very brief and of a purely technical nature, did not consist of outlines or precise calculations. Nevertheless, it allowed Bonnet to declare immediately that the Carayol design, proposed unsuccessfully as early as April 1967, could be labeled as correct.23 Had this outline not already been in existence, we would have had a difficult time understanding the information and might have suspected an attempt to mislead us. In fact, this was a reciprocal validation: Carayol’s sketch authenticated the seriousness of the source, while the latter confirmed the value of Carayol’s ideas. Without realizing it, as very few were aware of Carayol’s discovery (and surely not Cook), he had given us a big tip and unexpected assistance, as this information also freed us from the ministerial harassment to which we had been constantly subjected. From that moment, things moved briskly.

Encyclopedia Britannica:

Physicist Michel Carayol laid out what would be the fundamental idea of radiation implosion in an April 1967 paper, but neither he nor his colleagues were immediately convinced that it was the solution, and the search continued.

In late September 1967, Carayol’s ideas were validated by an unlikely source, William Cook, who had overseen the British thermonuclear program in the mid-1950s. Cook, no doubt at his government’s behest, verbally passed on the crucial information to the French embassy’s military attaché in London. Presumably, the British provided this information for political reasons. British Prime Minister Harold Wilson was lobbying for the entry of the United Kingdom into the Common Market (European Economic Community), which was being blocked by de Gaulle.

Sakharov sketch:

Note Added: Perhaps someone can translate part of this paper, which gives some details about the Chinese thermonuclear step, credit to Yu Min. Did they invent a mechanism different from Ulam-Teller? I can't tell from this paper, but I suspect the initial Chinese design used U-T. There are claims that Yu Min later developed, in the pursuit of miniaturization and improved safety, a qualitatively different design.

Yu Min was a student of Peng Huanwu (also a key figure in the bomb effort), who was a student of Max Born. Yu Min only recently passed, in early 2019!

Leo Szilard, the Intellectual Bumblebee (lecture by William Lanouette)

 

This is a nice lecture on Leo Szilard by his biographer William Lanouette. See also ‘An Intellectual Bumblebee’ by Max Perutz.

Wikipedia: Leo Szilard was a Hungarian-American physicist and inventor. He conceived the nuclear chain reaction in 1933, patented the idea of a nuclear fission reactor in 1934, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb.

How Alexander Sachs, acting on behalf of Szilard and Einstein, narrowly convinced FDR to initiate the atomic bomb project: Contingency, History, and the Atomic Bomb. 

Szilard wrote children's stories and science fiction. His short story My Trial as a War Criminal begins after the USSR has defeated the US using biological weapons.

I was just about to lock the door of my hotel room and go to bed when there was a knock on the door and there stood a Russian officer and a young Russian civilian. I had expected something of this sort ever since the President signed the terms of unconditional surrender and the Russians landed a token occupation force in New York. The officer handed me something that looked like a warrant and said that I was under arrest as a war criminal on the basis of my activities during the Second World War in connection with the atomic bomb. There was a car waiting outside and they told me that they were going to take me to the Brookhaven National Laboratory on Long Island. Apparently, they were rounding up all the scientists who had ever worked in the field of atomic energy ...

This story was translated into Russian and it had a large impact on Andrei Sakharov, who showed it to his colleague Victor Adamsky:

A number of us discussed it. It was about a war between the USSR and the USA, a very devastating one, which brought victory to the USSR. Szilard and a number of other physicists are put under arrest and then face the court as war criminals for having created weapons of mass destruction. Neither they nor their lawyers could make up a cogent proof of their innocence. We were amazed by this paradox. You can’t get away from the fact that we were developing weapons of mass destruction. We thought it was necessary. Such was our inner conviction. But still the moral aspect of it would not let Andrei Dmitrievich and some of us live in peace.

See also The Many Worlds of Leo Szilard (APS symposium). Slides for Richard Garwin's excellent summary of Szilard's work, including nuclear physics, refrigeration, and Maxwell's Demon. One of Garwin's anecdotes:

Ted Puck was a distinguished biologist, originally trained in physics. ‘With the greatest possible reluctance I have come to the conclusion that it is not possible for me personally to work with you scientifically,’ he wrote Szilard. ‘Your mind is so much more powerful than mine that I find it impossible when I am with you to resist the tremendous polarizing forces of your ideas and outlook.’ Puck feared his ‘own flow of ideas would slow up & productivity suffer if we were to become continuously associated working in the same place and the same general kind of field.’ Puck said, ‘There is no living scientist whose intellect I respect more. But your tremendous intellectual force is a strain on a limited person like myself.’

Puck was a pioneer in single cell cloning, aided in part by Szilard:

When Szilard saw in 1954 that biologists Philip Marcus and Theodore Puck were having trouble growing individual cells into colonies, he concluded that “since cells grow with high efficiency when they have many neighbors, you should not let a single cell know it’s alone”. This was no flippant excursion into psychobiology. Rather, Szilard’s idea to use a layered feeder dish worked, while the open dish had not (Lanouette, 1992: 396–397).

After the war Szilard worked in molecular biology. This photo of Jacques Monod and Szilard is in the seminar room at Cold Spring Harbor Lab. Monod credits Szilard for the negative-feedback idea behind his 1965 Nobel prize.

“I have … recorded” in my Nobel lecture, said Monod, “how it was Szilard who decisively reconciled me with the idea (repulsive to me, until then) that enzyme induction reflected an anti-repressive effect, rather than the reverse, as I tried, unduly, to stick to.”