Posts Tagged ‘Edward Teller’


Did Lawrence doubt the bomb?

Friday, September 4th, 2015

Ernest O. Lawrence was one of the giants of 20th-century physics. The inventor of the “cyclotron,” a circular particle accelerator, Lawrence ushered in an era of big machines, big physics, big budgets — Big Science, in short. And that came with ups and downs. I’ve recently finished a review for Science of Michael Hiltzik’s new Lawrence biography, Big Science: Ernest Lawrence and the Invention that Launched the Military-Industrial Complex. The full review is online but behind a paywall (if you want a copy, get in touch with me), but I am allowed to post the unedited version that I originally submitted, which in this case is about twice the size of the printed one, so maybe it’s interesting as an essay in its own right (so I may flatter myself). I found it hard to cram the story of Lawrence, and this book, in a thousand words (and brevity has never been my strength), because there is just so much going on and worth commenting on.

My wonderful Stevens STS colleague Lee Vinsel had a review in last week's issue of Science as well.

My wonderful Stevens STS colleague Lee Vinsel had a review in last week’s issue of Science as well.

Lawrence featured early into my education. I was an undergraduate at UC Berkeley, which means I was in Lawrence country. His laboratory literally perches above the campus, looking down on it. In various buildings on campus, it is not uncommon to come across a large portrait of the man. And any geeky child in northern California visits the Lawrence Hall of Science numerous times in the course of their education.

As a budding historian of science, what I found so incongruous about Lawrence was the way in which he embodied something of a paradox at the heart of particle physics. High-energy particle physics is for the most part a pretty “pure” looking form of science, trying to pull-off very elegant experiments with the most abstract of physical entities, and making the experimental evidence jibe with the theoretical understandings. When people want to point to evidence of objectivity in science, or to the places where theory gets vindicated in a very elegant way, they point to particle physics. And yet, to do these experiments, you often need big machines. Big machines require big money. Big money gets you into the realm of big politics. And so this very elegant, above-it-all form of science ends up getting tied to the hip of the military-industrial complex during and after World War II. How ironic is that?

The scientific staff of the University of California Radiation Laboratory with magnet of unfinished 60-inch cyclotron. Lawrence is front and center. Oppenheimer stands in back. Credit: Emilio Segrè Visual Archives.

The scientific staff of the University of California Radiation Laboratory with magnet of unfinished 60-inch cyclotron, 1938. Lawrence is front and center. Oppenheimer stands in back. Credit: Emilio Segrè Visual Archives.

As you can pick up from both the published and draft review, I had mixed feelings about Hiltzik’s book. I think people who have never read anything about Lawrence before will find it interesting though potentially confusing, because it bounces around as a genre. One can’t really tell what Hiltzik thinks about Lawrence. Half of the time Hiltzik seems to want to make him out to be the Great Hero of 20th century science. (Sometimes this gets hyperbolic — Lawrence was a big character, to be sure, but he was still of his time, and it does some historical injustice to claim that everything related to Big Science necessarily is laid at his door. To claim that Big Science was “a solitary effort,” as Hiltzik does, is as self-contradictory as it is untrue.) The other half of the time, though, Hiltzik is pointing out what a huge jerk he could be, how bad of a scientist he could be, and how he sullied himself with some of the worst sorts of political engagements during the Cold War. Everyone gets on Edward Teller for being a far-right, pro-nuke, anti-Communist jerk, but even Teller thought Lawrence could be an extremist when it came to these things.

This ambivalent mix — Lawrence as great, Lawrence as terrible — never gets resolved. One could imagine it being talked about as two sides of the same coin, or some sort of synthetic whole emerging out of these two perspectives. But it just doesn’t happen in the book. In my own mind, this is the somewhat Faustian result of Lawrence’s “cult of the machine” (as I titled my review), where the Bigness required for his science ended up driving extremes in other parts of his life and politics as well.

The intense Ernest Lawrence. Credit: Emilio Segrè Visual Archives.

The intense Ernest Lawrence. Credit: Emilio Segrè Visual Archives.

Serious historians of 20th-century physics will find little new in Hiltzik’s book, either in terms of documentation or analysis. He relies heavily on secondary sources and the archival sources he does consult are the standard ones for this topic (e.g. the Lawrence papers at UC Berkeley). The book also contains several avoidable errors of a mostly minor sort, but the kinds of misconceptions or misunderstandings that ought to have been caught before publication (some of which I would like to imagine would jump out to anyone who had read a few books on this subject already). I did not mention these in the formal review, because there was really not enough space to warrant it, and the book never hinged on any of these details, but still, it seems worth noting in this more informal space.1

That aside, the book reminded me of one of the strangest aspects of Lawrence’s relationship with the bomb — whether he thought it was a good idea to drop one on Japan without a warning. As I’ve discussed before, the question of whether a “demonstration” should be made prior to shedding blood with the bomb was a controversial one on the project. A Scientific Panel composed of J. Robert Oppenheimer, Arthur H. Compton, Enrico Fermi, and Ernest Lawrence were asked to formally consider the question in the June of 1945. They formally recommended that the bomb be dropped on a city without warning: “we can propose no technical demonstration likely to bring an end to the war; we see no acceptable alternative to direct military use.”

Lawrence and the Machine. (And M. Stanley Livingston, the one-time grad student who got the machines working.) I like the symbolism of this photo — Lawrence looking at the newest piece of hardware, Livingston with a hand on it, staring the camera down. They are with the 85-ton magnet of the 27" cyclotron, circa 1934. Credit: Emilio Segrè Visual Archives.

Lawrence and the Machine… and M. Stanley Livingston, the one-time grad student who got the machines working. I like the symbolism of this photo — Lawrence looking at the newest piece of hardware, Livingston with a hand on it, staring the camera down. They are with the 85-ton magnet of the 27″ cyclotron, circa 1934. Credit: Emilio Segrè Visual Archives.

But there’s potentially more to it than just this. Case in point: in the archives, one finds a letter from Karl K. Darrow to Ernest Lawrence, dated August 9th, 1945. Darrow was a friend of Lawrence’s, and a fellow physicist, and a noted popularizer of science in his day. And this is an interesting time to be writing a letter: Hiroshima has already occurred and is known about, and Nagasaki has just happened (and Darrow may or may not have seen the news of it yet), but the war has not ended. This period, between the use of the bomb and the cessation of hostilities, is a very tricky one (a topic Michael Gordin has written a book on), because the meaning of the atomic bomb had not yet been cemented. That is, was the atomic bomb really a war-ending weapon? Or just a new way to inflict mass carnage? Nobody yet knew, though many had uncertain hopes and fears.

August 9th is also a tricky period because this is around the time in which the first casualty estimates from Hiroshima were being received, by way of the first Japanese news stories on the bombing. They were much higher than many of the scientists had thought; Oppenheimer had estimated them to be around 20,000, and they were hearing reports of 60,000 or higher. For some, including Oppenheimer, they saw this as a considerable difference with respects to how comfortable they felt with the attacks.

"Best Copy Available," the last excuse of the wicked. Click here for the original with a transcription appended.

“BEST COPY AVAILABLE” is the last excuse of the wicked. Click here for the original with a transcription appended.

This context is relevant to making sense of the Darrow letter. The archival document is hard to read, and in some places illegible, so I’ve included a transcription that I typed up from the best of my reading of it. The import of it is pretty easy to take away, though, even with a few phrases being hard to read. Here is an excerpt of the key parts:

Dear Ernest:

This is written to you to put on the record the fact that you told me, on August 9, 1945, that you had presented to the Secretary of War by word of mouth the view that the “atomic bomb” ought to be demonstrated to the Japanese in some innocuous but striking manner before it should be used in such a way as to kill many people. You made this presentation in the presence of Arthur Compton, Fermi, Oppenheimer and others, and spoke for about an hour. The plan was rejected by the Secretary of War on the grounds that (a) the number of people to be killed by the bomb would not be greater in order of magnitude than the number already killed in the fire raids, and (b) an innocuous demonstration would have no effect on the Japanese. […]

I think that it is not far-fetched nor absurd to conjecture that in time to come, people will be saying “Those wicked physicists of the ‘Manhattan Project’ deliberately developed a bomb which they knew would be used for killing thousands of innocent people without any warning, and they either wanted this outcome or at least condoned it. Away with physicists!” It will not be accepted as an excuse that they may have disapproved in silence. We do not excuse the German civilians who accepted Buchenwald while possibility disapproving in silence.

I think that if the war ends today or tomorrow or next week, this sort of criticism will not be heard for a while, and yet it will be heard eventually — and particularly it will be heard if at a time should come when some other power may be suspected of planning to use the same device on us. In other words, if the use of this weapon without forewarning has really brought quick victory, this fact will delay but will not indefinitely prevent the emergence of such an opinion as I have suggested. It may then be of great value to science, if some scientist of very great prominence has already said that he tried to arrange for a harmless exhibition of the powers of the weapon in advance of its lethal use.2

There is a lot going on in this letter. First, it makes it clear that Lawrence and Darrow had a discussion about the demonstration matter right around the time of the Nagasaki bombing. It is also clear that Darrow came away with the impression that Lawrence was deeply unsure about the logic of bombing without warning. Now the amount of pontificating by Darrow makes it seem like Darrow might be reading into what Lawrence told him more than Lawrence said — Darrow’s concerns are not necessarily Lawrence’s concerns. But it does seem clear that Darrow thinks he is setting something into the record that might be useful later, and that even if the war ended soon, there were going to be doubts to be contended with, and the fact that Lawrence was worried about using the bomb might somehow be exculpatory.

Darrow’s letter was received on August 10th (so it is stamped), but it isn’t clear when Lawrence read it. He did not reply until August 17th, 1945, by which point hostilities with Japan had ended. This is a big thing to point out: the Darrow-Lawrence conversation, and original letter, took place at a time when it wasn’t clear whether the bombs would actually be credited with ending the war. By August 17th, Japan had already pressed for an end of the war and had credited the atomic bomb in part with their defeat.3 If Lawrence ever did have doubts, they were gone by August 17th:

Dear Karl:

In reply to your letter of August 9th, you have the facts essentially straight, excepting that I didn’t believe I talked on the subject of the demonstration of the bomb as long as an hour. I made the proposal briefly in the morning session of the Secretary of War’s committee, and during luncheon Justice Byrnes, now Secretary of State, asked me further about it, and it was discussed at some length, I judge perhaps ten minutes.

I am sure it was given serious consideration by the Secretary of War and his committee, and gather from the discussion that the proposal to put on a demonstration did not appear desirable […] Oppenheimer felt, and that feeling was shared by Groves and others, that the only way to put on a demonstration would be to attack a real target of built-up structures. 

In view of the fact that two bombs ended the war, I am inclined to feel they made the right decision. Surely many more lives were saved by shortening the war than were sacrificed as a result of the bombs. […]

As regards criticism of science and scientists, I think that is a cross we will have to bear, and I think in the long run the good sense of everyone the world over will realize that in instance, as in all scientific pursuits, the world is better as a result.4

To me, this letter reads as something of a kiss-off to Darrow’s doubts — and maybe to doubts Lawrence himself might have once held. Darrow recalls Lawrence telling him it was an hour-long discussion, and a major conflict between the soulful Lawrence and the unfeeling others. In Lawrence’s post-victory recollection, it becomes a 10-minute talk, duly taken seriously but not that hard of a question to answer, and in the end, the ends justified the means, neat and tidy.

Lawrence, Glenn T. Seaborg, and J. Robert Oppenheimer operate a cyclotron for the cameras in a postwar photograph. Small historical detail (literally): one can find this photograph sometimes flipped on its horizontal axis. Which is the correct orientation? One can take guesses based on rings, handedness, etc., but the copy of the scan that I have has sufficient resolution that you can read the dials, which I think resolves the question. Credit: Emilio Segrè Visual Archives.

Lawrence, Glenn T. Seaborg, and J. Robert Oppenheimer operate a cyclotron for the cameras in a postwar photograph. Small historical detail (literally): one can find this photograph sometimes flipped on its horizontal axis. Which is the correct orientation? One can take guesses based on rings, handedness, etc., but the copy of the scan that I have has sufficient resolution that you can read the dials, which I think resolves the question. Credit: Emilio Segrè Visual Archives.

So where lies the truth? Was Lawrence a doubter at the time of the Nagasaki bombing, only to lose all doubts after victory? Was Darrow projecting his own fears onto Lawrence at their meeting? I suspect something in between — with a second bomb so rapidly dropped after the first, Lawrence and Darrow might have both been wondering if these weapons would really end the war (much less all war), if they weren’t just a new-means of old-fashioned mass incineration. Maybe Lawrence exaggerated, or gave an exaggerated impression, of his debate over the demonstration.

One interesting piece is that the story of “doubts” can, as Darrow implied, be made exculpatory without necessarily calling into question the wisdom of the bombing. That is, if the story is about how the scientists really didn’t want to use the bomb, but couldn’t see a better way around it, then you get (from the perspective of the scientists involved) the best of both worlds: they still have souls, but they also have justification. This is how Arthur Compton presents the meeting in his 1956 book, Atomic Quest, which takes more the Darrow perspective of a fraught Scientific Committee, Ernest Lawrence as the final hold-out, but with “heavy hearts” they recommend direct military use.5

Lawrence and the Machine (or, at least, one of them). I like the idea that Lawrence was doing his research wearing a full suit and tie. Credit: Emilio Segrè Visual Archives.

Lawrence and the Machine (or, at least, one of them). I like the idea that Lawrence was doing his research wearing a full suit and tie. Credit: Emilio Segrè Visual Archives.

J. Robert Oppenheimer, for his part, later said he had “terrible” moral scruples about the dropping of the bomb, of killing at least 70,000 people with the first one, though, notably, he never said he regretted doing it. He did, however, think that physicists had “known sin” and required an active role in future policy regarding these new weapons, if only to keep the world from blowing itself up. Lawrence parted ways with his former friend and colleague after World War II, remarking that “I am a physicist and I have no knowledge to lose in which physics has caused me to know sin” and chastising those scientists (like Oppenheimer) who thought that they ought to be getting involved with policymaking, as opposed to research — or bomb-building.

If Lawrence had doubts, he left by the wayside once the promise of victory was in the air, and he happily and seemingly without misgivings hitched himself permanently to the burgeoning military-industrial complex. He was part of the anti-Oppenheimer conspiracy that led to the 1954 security hearing, he worked closely with Edward Teller and Lewis Strauss to attempt to scuttle attempts at test bans and moratoriums, he pushed for greater quantities of bigger bombs, he sold out colleagues and friends, participating in McCarthyist purges with gusto. He was also the inventor of the cyclotron, a physicist of great importance, and one of the creators of the Big Science approach to doing research. These are not incompatible takes on a complex human being — but when we celebrate the scientific accomplishments, we do history poorly if we forget the parts that are arguably less savory.

  1. A short list of the serious errors that jumped out at me follows. Page 227: Hiltzik says that Hanford (as a site) could only produce half a pound of plutonium every 200 days. That this is a misunderstanding should be pretty obvious given that they managed to come up with 27 lbs of it (for Trinity and Fat Man) by late July 1945 despite starting B-Reactor in late 1944. I don’t know where the 200 days figure comes from, but the Hanford reactors could get 225 grams (about half a pound) of plutonium for every ton of uranium they processed, and each reactor was designed to process 30 tons of uranium per month at full power (though it took several months for the plutonium to be extracted from any given ton of exposed uranium). Because there were three reactors, that means that optimally Hanford could produce about 20 kg (45 lbs) of plutonium per month. In practice they did less than that, but half a pound every 200 days is just wrong, and if true would have made two of the World War II bombs impossible. Page 292: The book gets the information about the Trinity core geometry wrong — it says it is a hollow shell that was “crushed into a supercritical ball.” Rather, the Christy core was a mostly solid core (there was a small hole for the initiator) whose density was increased by the high explosives. Hollow shell designs were considered, and were later used in the postwar, but the wartime devices did not use them. This is one of those errors that won’t die — often repeated despite a wealth of evidence to the contrary. Page 386: Hiltzik refers to the Soviet test Joe-4/RDS-6s as a “fizzle.” This is incorrect terminology and implies that it did not achieve its target yield. It was not a staged thermonuclear weapon, but it was not a fizzle — it did what it was supposed to do, and was not a disappointment in any way. Page 405: Hiltzik, perhaps by reading too much Ralph Lapp (who was very smart but sometimes got things wrong), doesn’t seem to understand how the so-called “clean bomb” would have worked. The higher the proportion of the weapon that comes from fusion reactions as opposed to fission reactions, the smaller the amount of fallout that would result. The contamination power of a weapon is not related to its total yield so much as its fission yield. The area of contamination does relate to the yield (so a 10 megaton weapon with only 1% of its yield from fission does spread those fission products over a wide area), but the intensity of the contamination does not (the level of radiation would be extremely low compared to a “dirty” hydrogen bomb that derived at least half of its power from fission). One can object that the “clean bomb” was at best a cleaner bomb, and doubt both its wisdom and the sincerity of its proponents, but the idea itself was not a hoax. Page 416: Hiltzik says that Hans Bethe “flatly refused” to join the hydrogen bomb work. This is not correct. Bethe initially refused, and then later joined the thermonuclear project at Los Alamos and made several important contributions (to the degree that he is sometimes referred to as the “midwife” of the hydrogen bomb). Bethe’s wavering position on this is very aptly discussed in S.S. Schweber’s In the Shadow of the Bomb: Oppenheimer, Bethe, and the Moral Responsibility of the Scientist. There are a few other nitpicks (e.g. saying that “the test ranges remained silent” from 1958-1961… only true if you ignore France), but those are the ones that really stood out as outright errors. The most irritating misrepresentation (not strictly a factual error so much as an omission) is the fact that while Lawrence’s Calutrons were indeed an important part of the overall enrichment system used to make the fuel for the Hiroshima bomb (though not the only part), they were shut down in the early post war because they were not as efficient as the gaseous diffusion method. One would not get that impression from Hiltzik’s book, and it is relevant inasmuch as evaluating the importance of Lawrence’s method to the war — it was a useful stop-gap, but it was not a long-term solution. []
  2. Karl K. Darrow to Ernest O. Lawrence (9 August 1945), Ernest O. Lawrence papers, Bancroft Library, UC Berkeley. Copy in the Nuclear Testing Archive, Las Vegas, Nevada, accession number NV0724362. []
  3. Whether the bomb did or did not actually sway the Japanese high command is not a completely settled question, but does not matter for our purposes here — we are talking about what Lawrence et al., might have thought, not internal Japanese political machinations and motivations. []
  4. Ernest O. Lawrence to Karl K. Darrow (17 August 1945), Ernest O. Lawrence papers, Bancroft Library, UC Berkeley. Copy in the Nuclear Testing Archive, Las Vegas, Nevada, accession number NV0724363. []
  5. Arthur Compton, Atomic Quest: A Personal Narrative (New York: Oxford University Press, 1956), 239-241. []

The Spy, the Human Computer, and the H-bomb

Friday, August 23rd, 2013

One of the most enigmatic documents in early Cold War nuclear history is the so-called Fuchs-von Neumann patent. It was Los Alamos secret patent application number S-5292X, “Improvements in method and means for utilizing nuclear energy,” and dates from April 1946. It is mentioned, cryptically, often with heavy redaction, in many official histories of the hydrogen bomb, but also has recently surfaced as an object of historian’s speculation. The most obvious reason for its notoriety comes from its authors, but its importance  goes deeper than that.

The Los Alamos identification badges for Klaus Fuchs and John von Neumann. Courtesy of Los Alamos National Laboratory.

The Los Alamos identification badges for Klaus Fuchs and John von Neumann. Courtesy of Los Alamos National Laboratory.

The co-inventors were Klaus Fuchs and John von Neumann. Fuchs was a brilliant German physicist who was later exposed as the most important of the Soviet spies at Los Alamos. Von Neumann was a brilliant Hungarian mathematician and physicist, a “ringer” they brought in especially to help manage the explosive lens program, and is generally considered one of the smartest people in the 20th century. As one of the major contributors to the invention of modern computing, it was often remarked in his time that he was much smarter than the machines he was developing — he could do crazy-complicated math in his head without breaking a sweat. And he was a vehement anti-Communist at that — a man who spoke openly about the benefits of instigating thermonuclear war with the Soviets. So on the face of it, it’s an improbable match-up — the Soviet spy and the anti-Communist human computer. Of course, viewed in context, it’s not so improbable: they were both talented physicists, both worked at Los Alamos, and nobody at the lab knew Fuchs was a spy.

The patent is interesting to historians because it allegedly plays a key role in answering the (still quite murky) question of whether the Soviets got the H-bomb through espionage or by their own hard work. We know that Fuchs passed it on to the Soviets — the question is, what did it contain, and how did the Soviets use it? The reason it shows up recurrently is because the patent is allegedly one of the first suggestions of the concept of radiation implosion, that is, using the radiation output of a fission bomb as a means of initiating fusion. In 1951, this would become one of the central components of the so-called Teller-Ulam design of the hydrogen bomb, on which all subsequent hydrogen bombs were based.

Record of invention for the Fuchs-von Neumann design, "Improvements in Method and Means for Utilizing Nuclear Energy."

Record of Invention for the Fuchs-von Neumann design, “Improvements in Method and Means for Utilizing Nuclear Energy.” This copy is from the records of the Joint Committee on Atomic Energy in the Washington, DC, National Archives.

The contents of the patent itself is still officially secret in the United States. What is officially declassified  is little more than its title and some relevant dates — not much to go on. All descriptive aspects of it are totally classified. Which, generally speaking, makes it very hard to evaluate the aforementioned question of how useful it would have been to the Soviet Union, since we don’t officially know what is in it.

But in the last couple of years, things have changed on this latter point. The patent application is still classified in the United States.1 But the contents of the patent appear to have been declassified, and published, in Russia. I’ve talked a bit in the past about how the Russians have declassified a bunch of information about the American bomb project that they got from espionage, despite the fact that this information is still probably classified in the United States. It would be really, really wonderful to know the back-story on why they do this, and whether there is any discussion with American classification authorities before the Russians start releasing information about old American bomb designs. The book series in question is Atomni’ Proekt SSSR (USSR Atomic Project: Documents and Materials), which is cheerfully described on the inside as “intended for everybody interest in the history of the Soviet Atomic Project.” Indeed!

In this case, the late Herb York told me that the late German Goncharov, one of the editors of the Atomni’ Proekt SSSR series, approached him and told him somewhat informally that he thought this information should be declassified. York told me that he couldn’t really officially respond to Goncharov about this, but he showed it to some people in Livermore, but they weren’t very interested. Anyway, whatever the case, Goncharov apparently got the whole thing published in 2009 in volume 3, book 1 of the series.

Fuchs-von Neumann H-bomb design

The above image, supposedly the Fuchs-von Neumann concept, had appeared in a few other sources prior to that, but not with explanatory text. The only person who has published a serious analysis of it is the physicist and historian Jeremy Bernstein, who wrote about it in Physics in Perspective in 2010.2 At the time, Bernstein only had access to the diagram and its above legend, which was first seen in print in Gregg Herken’s Brotherhood of the Bomb. Bernstein’s caption of the above device (which he credits Carey Sublette for deciphering) is as follows:

The design for thermonuclear ignition that Klaus Fuchs turned over to his Soviet control in March 1948. The detonator (box) on the left represents a gun-type fission bomb consisting of a projectile and target of highly enriched uranium (71 kg of 70% pure U235), which when joined form a supercritical mass and produce an explosive chain reaction. The projectile is carried forward by its momentum, striking the beryllium-oxide (BeO) capsule on the right, which contains a liquid 50:50 D–T mixture, compressing it by a factor of about 3, as represented by the outer circle. The radiation produced in the fission bomb heats up the BeO capsule, producing completely ionized BeO gas, which exerts pressure on the completely ionized D–T gas, compressing the capsule further to an overall factor of about 10, as represented by the inner circle.

The interpretation is pretty good, considering the lack of additional source material! But the Russians have since released the entire document — including its original description of how it is meant to work, in the original English. Here is an excerpt:

The detonator is а fission bomb of the gun type. The active material is 71 kg of 40% pure U233 [sic].3 The plug (48.64 kg) sits in the projectile, which is shot bу the gun into the target, the remaining 22-24 kg sits in the target. The tamper is ВеО. The fission gadget has аn efficiency of 5% (calculated). The tamper, which is transparent for the radiation from the fission bomb, is surrounded bу an opaque shell which retains the radiation in the tamper and also shields the booster and main charge against radiation.  […]

The primer contains 346 gm of liquid D-Т in 50:50 mixture, situated in the tamper. It is first compressed bу the projectile to 3-fold density. This precompression may not bе necessary. As the tamper and primer аге heated bу the radiation, the primer is further compressed, possibly to 10-fold density. (Radiation transport equalises the temperature in primer and tamper, and gives therefore rise to а pressure differential.) The compression opens the “gap” for the ignition of the primer. The primer is likely to have а very high efficiency (~80 %) of energy release.

The booster beyond the radiation shield contains D with about 4% Т. It is ignited bу the neutrons from the primer. Beyond the booster is the main charge of pure D, а cylinder of about 30 сm radius to contain the neutrons and arbitrary length.

So what’s happening here is that the big piece of uranium is being shot against another piece. In the process, it rams into a bunch of fusion fuel (the 50:50 deuterium-tritium mixture), and just mechanically compresses it by a factor of 3. Just brute force. Then the fission bomb starts to detonate, using its radiation to ionize and heat the beryllium-oxide tamper. This causes it to ionize and blow off, compressing that 50:50 DT mixture, and starting a fusion reaction (they hope). This produces a huge number of neutrons, which then go and hit some more fusionable fuel (a DT mixture with only 4% tritium). The neutrons from this then go on to continue and ignite a final reservoir of pure deuterium “of arbitrary length.”

The report then estimates that with 1 cubic meter of deuterium, it would have a blast range of 5 miles, a flash burn range of 10 miles, and prompt gamma radiation for 2 miles. It’s not clear what values they mean exactly for those ranges (is blast 1 psi, 5 psi, 10 psi, 20 psi?), but playing with the NUKEMAP makes me think they are talking about something in the megaton range. For 10 tons of deuterium, it says: “Blast ~ 100 square miles, Flash burn to horizon оr 10,000 square miles if detonated high up. Radioactive poison, produced bу absorption of neutrons in suitable materials, could bе lethal over 100,000 square miles.” Which is something in the many tens of megatons.

So was this radiation implosion? Well, kind of. The design uses the radiation energy to blow up the tamper, basically, compressing some fusion fuel. That’s part of how the Teller-Ulam design would later work. But the entire thing is done in the context of the non-workable Classical Super — the idea that you can start a fusion reaction at one length of a column of fusionable material and it will propagate down the rest of it. Radiation implosion, here, is really just trying to get a better initial “spark” of energy to start the Classical Super reaction. This is very different from Teller-Ulam, where the complete implosion of the secondary is a key and fundamental aspect. All of which is to say, while this is a kind of radiation implosion (mixed in with a lot of other complicated things), it’s pretty far from what is required to make a working hydrogen bomb, because the Classical Super idea just doesn’t work. The fusion reaction of the sort proposed just can’t sustain itself. Even Fuchs and von Neumann appear to have only perceived the importance of their invention as reducing the amount of tritium needed versus other Classical Super designs.4

The "Classical Super" design from 1946. A gun-type design is surrounded by a beryllium oxide tamper. There is a tubealloy (depleted uranium) shield to keep radiation off of the fusion fuel. The idea is to ignite a fusion reaction in a D+T mixture, which then ignites fusion reactions in a pure D mixture of arbitrary length.

The unworkable “Classical Super” design from 1946. A gun-type design is surrounded by a beryllium oxide tamper. There is a tubealloy (depleted uranium) shield to keep radiation off of the fusion fuel. The idea is to ignite a fusion reaction in a D+T mixture, which then ignites fusion reactions in a pure D mixture of arbitrary length. The Fuchs-von Neumann device is, in effect, just an attempt make the initial ignition easier, and does not question the (faulty) underlying assumption about propagation of the fusion reaction.

So what did the Soviets do with this information? Other documents in the series give some indication of that, and I’ve included the full set here (warning: large PDF, 13.5 MB), although it is completely in Russian.

The 1948 intelligence data is identified as “Material No. 713.” It includes a brief, near verbatim summary (Document No. 32) by the physicist Yakov Terletsky (the same one who interviewed Bohr at Beria’s request), as well as a brief report by Terletsky explaining what this material gave them compared to previous information about the American H-bomb work (Document No. 33). The latter is interesting; they seem most interested in the new theoretical information about the conditions required for deuterium fusion than they are about the specifics of the designs given. The strongest phrase is one where Terletsky says that the intelligence information will help them get beyond general, theoretical calculations and move towards the actual design or construction of a ‘deuterium superbomb, and thus reduce the time required for the practical implementation of the superbomb idea.”5

Document No. 34 includes an order by Beria that Kurchatov and Vannikov be required to write analyses of the intelligence information, and that Khariton be consulted on the information. This was made just a few days after Terletsky’s report. Vannikov and Kurchatov’s analysis is included as Document 35. They seemed quite encouraged and interested in the intelligence, and claim it will help them a lot. Of note is that they in particular mention that, among the useful things in the document, they thought that “the ideas about the role of particles and photons in the transmission of the explosion to the deuterium are new.”6 So they do seem to have picked up on that, though it is again mixed into a lot of other details. They then used this material to propose that the USSR start a full-fledged Super program, along the lines of the unanswered questions (and even some of the answered ones) reflected in the intelligence information.

The end of Beria's April 1948 memo written as a result of the Fuchs intelligence, instructing that Khariton's opinion should be sought, especially with respects to the future work of the KB-11 (Arzamas-16) laboratory.

The end of Beria’s April 1948 memo written as a result of the Fuchs intelligence, instructing that Khariton’s opinion should be sought, especially with respects to the future work of the KB-11 (Arzamas-16) laboratory.

One thing that comes out in this as well is that the Soviet scientists at this point only had one other significant intelligence source related to the Super work, from late 1946 (Material No. 462, which I’ve uploaded here.) This appears to be a summary of the Super lectures that Enrico Fermi gave at Los Alamos, and is focused entirely on the Classical Super approach to the bomb, with many uncertainties. If these two caches were the only significant espionage they had on the American Super program before starting their own Super program, that’s pretty interesting in and of itself, and helps put some pretty strict limitations on what they would have gotten out of the data.

Looking at all this, even with the knowledge that there is probably a lot more to the story, I come away with the following conclusions. First, Bernstein is probably right when he says that the Fuchs-von Neumann approach wouldn’t have helped the Soviets very much in terms of arriving at the Teller-Ulam design. As he puts it:

Part of the irony of this story is that the unlikely collaborators, John von Neumann and Klaus Fuchs, produced a brilliant invention in 1946 that could have changed the whole course of the development of the hydrogen bomb, but was not fully understood until after the bomb had been successfully made.

I think perhaps this might go a little too far in praising radiation implosion — it is brilliant of a sort, but it is only one piece in the overall puzzle. The bigger issue on the road to the Teller-Ulam design was not so much the idea that the radiation could be used to transmit the energy, or even to implode the secondary, but getting away from the Classical Super notion of starting a small reaction that would then propagate onward. Indeed, the real breakthrough in the end appears to have been getting out of that mindset altogether. Ulam’s big idea was of total compression of the secondary by putting the whole thing in a “box,” which Teller then realized could be done more efficiently with radiation implosion. Radiation implosion is just a part of the overall mechanism, one which Ulam later insisted was actually not even required.

But my second, perhaps deeper conclusion is that this intelligence appears to have been much more important than has been previously thought. It didn’t give the Soviets the right idea of how to make an H-bomb. But it did seem to convince them that the Americans were taking this work very seriously, and making serious progress, and that they should set up their own dedicated H-bomb program as soon as possible. That’s a big deal, from an organizational standpoint, arguably a much bigger deal than the idea that it gave them some hint at the final design.

The Soviets were talking about a serious H-bomb program in 1948, before they had a fission bomb, and before USA was really committing itself to making a hydrogen bomb. In this sense, while it isn’t clear that this intelligence saved them any real time on the bomb, it did convince them it was worth spending time on. In the end, that was what produced their successful hydrogen bomb models, in the end. Not the intelligence itself, but the program spurred on by the intelligence. And so in that sense, Fuchs does have a very real role in the Soviet hydrogen bomb program, even if his specific ideas were not realized to be relevant until after the fact. Our focus on the importance of individual design secrets can lead us to underestimate the importance of programmatic and organizational decisions in weapons development.7 We tend to focus on the question of, “did this fact get transmitted, and was it appreciated?” But facts, by themselves, do not build bombs. What they can do, though, is inspire scientists to think that the bombs can and should be made, so that they start the laborious process of actually making them. If the Fuchs intelligence did have this result, then it was very important indeed.

  1. Note that it is, and probably will always be, an application. Secret patent applications cannot be granted until they are non-secret. And even then, the Atomic Energy Act of 1946 explicitly bans the patenting of atomic bombs. For the long, thrilling history of secret atomic patents, check out my page on them and my various articles on the history of the policy. []
  2. Jeremy Bernstein, “John von Neumann and Klaus Fuchs: an Unlikely Collaboration,” Physics in Perspective 12 (2010), 36-50. []
  3. The “detonator” description is very strange. For one thing, using only 40% enriched uranium (I am sure that the U-233 is a typo, because it is not in the Russian version, but the 40% is repeated in both) seems strange for 1946, and there is a marked difference between the specificity of one part of the gun-type design (48.64 kg) and the other (22-24 kg). This may be some kind of strange transcription error; the original drawing that the above diagram is based on says 22.36 kg. 5% efficiency is ridiculously high for such a description, too — “Little Boy” had about a 1% efficiency with 80% enriched uranium. If 5% of the U-235 in the “detonator” underwent fission, it would be around 24 kilotons in yield — somethings quite achievable by less speculative means. []
  4. The 1946 Record of Invention describes the object of the device as follows: “To provide an improved method and means for initiating a self-sustaining thermo-nuclear reaction which minimizes the amounts of materials employed.” (My emphasis.) When you compare this design with other Classical Super designs, it is clear, I think, that they are really trying to keep the amount of tritium down to a minimum, by starting the fusion with the heavy compression of a very small tritium-rich zone. Given that in 1946, the supply of tritium was minuscule, this would be a pretty appealing aspect of such a design. []
  5. “Материал #713а, в целом, позволяет перейти от общих теоретических расчетов к конструированию дейтериевой сверхбомбы и т[аким] о[бразом] сократить время, необходимое для практического осуществления идеи сверхбомбы.” []
  6. “Приведенные в материале #713а принципиальные соображения о роли трития в процессе передачи взрыва от запала из урана-235 к дейтерию, соображения о необходимости тщательного подбора мощности уранового запала и соображения о роли частиц и квантов при передаче взрыва дейтерию являются новыми.” []
  7. Michael Gordin makes this point excellently in his excellent Red Cloud at Dawn when discussing why the Smyth Report is actually a pretty important document for the Soviets: it didn’t give them any details about how to build a bomb, but it did tell them how to start a bomb-building research program. []

George Gamow and the atomic bomb

Friday, January 18th, 2013

George Gamow stands out as a colorful physicist among a generation of colorful physicists. He was a known wit, a friend to many of the “golden generation” of physicists, and — on top of all that — was a Russian émigré who had made a dramatic defection from the Soviet Union during a Solvay Conference. He was also a well-known popularizer of science, authoring well over a dozen works of physics aimed at the general public, often illustrated with his own amusing little drawings. He was quite a card: who else adds a scientist’s name to a massively important paper just to make a silly pun?

George Gamow, laughing and smoking, probably ca. the 1950s. Photo from the AIP Emilio Segrè Visual Archives.

George Gamow, laughing and smoking, probably ca. the 1950s. Photo via the AIP Emilio Segrè Visual Archives.

(Later in life, he became a very difficult person to be around, on account of his alcoholism. It was this fact that made me a little surprised that there was a free wine bar sponsored in the name of George Gamow at a meeting of the History of Science Society a few years back.)

Gamow’s scientific interests were all over the place — he was completely uninterested in disciplinary boundaries — and he was enormously influential on his peers as a “program builder.”1  It’s a little-known fact that Edward Teller came up with the idea of using a solid core of plutonium in the implosion design — an intuition he had because of his work with Gamow on the molten, compressed iron core of the Earth.2 Gamow’s work on nucleosynthesis and the Big Bang was immensely important to the advancement of cosmological thinking. Incidentally, Gamow did not like the term “Big Bang,”  because it sounded too much like nukes. He later even had an excursion into molecular biology.

But during World War II, Gamow didn’t work on the atomic bomb, though he continued to work on nuclear physics. One of the most charming letters I’ve found in the archives was written by Gamow to Vannevar Bush on August 12, 1945. You will note, of course, that this comes just three days after the bombing of Nagasaki, and is the same day the Smyth Report was released. In a clear but stylized handwriting, with a touch of refugee’s English, Gamow wrote the following letter to Bush:3

Click image to view PDF.

Click image to view PDF.

Aug 12th, 1945
19 Thoreau Drive
Bethesda, Md.

Dear Dr. Bush,

I am writing to you because I think you are the best man to advice me what to do. As you know I was in no way connected with the project of “atomic bomb” developement, while on the other hand, working all my life on nuclear physics, I naturally could not help not thinking about it and have rather clear ideas about the possibilities involved etc. As long as the whole thing remained a supersecret I was naturally trying to hold all my thoughts to myself. However now, when the thing exploded and all the newspapers are full of informations, I wonder where the boundary between what can and what cannot be told should be placed. Thus, for example, in my course of nuclear physics which I am giving in G.W.U. this summer I will have to speak next week about nuclear transformations, thermonuclear reaction, and nuclear chain reactions. Should I entirely avoid mentioning explosive reactions or not?

Again, I am now preparing the new edition of my Book on Nuclear Physics for Oxford Univ. Press. How much could be told in it about this part of the problem? Finally I was recently asked to write a small popular book on Atomic Energy. Must I reject such offer or not?

You understand of course that in all these cases the question is not about the technical details which I do not know, but about broad “purely scientific” point of view. As the matter of fact I do not think I know much more on the subject that the scientists in other countries, as for example in Soviet Russia, know at present, so that such utterings on my part will hardly be of any particular use for the “competitors.” Still, I would not like to do anything in this direction, without first receiving your advice.

Hoping to hear from you soon

Your very truly G Gamow.

Gamow’s concern was not unique to him, though he was a little ahead of the curve when it came to expressing it. He, like most other physicists, quickly saw that nuclear physics was going to become a much more troublesome thing in the age of atomic bombs. One of the biggest concerns at the time, by those inside the bomb project and those not, was that if nuclear physics became a top-secret area, it would severely impact the education of new physicists.

His letter did not go unnoticed; Vannevar Bush wrote him back a careful reply two days later, pointing out that the Smyth Report was released at almost the same time that Gamow’s letter was written, and that one of its explicit purposes was to make that firm line of security visible to folks like Gamow. Bush then offered up this bit of speculation:

I have no doubt that later there will be constituted in some way an official body to determine the proper bounds of scientific discussion, and undoubtedly competent scientists will be present on any such body. How this may possibly be done it is too early to know. However, in the interim there is a guide in the form of a report [the Smyth Report] and after the body is established there will be a place to turn which anyone can use who may be in doubt. 

The reality was somewhat more complicated than this, in the end. Policing “the proper bounds of scientific discussion” was ostensibly the role of the Atomic Energy Commission, but they found it quite hard to do such a thing in practice.

Gamow was, in the end, somewhat sucked into the weapons complex. He was a lecturer to US Naval Officers on fission physics just before Operation Crossroads, and later he was involved in the work on the hydrogen bomb, at Los Alamos. While there he drew this rather unusual little drawing celebrating the discovery/invention of the Teller-Ulam design in 1951:4

Gamow's drawing of Ulam and Teller, March 1951

What does it mean? Stanislaw Ulam as a very Bugs-Bunnyish hare, Edward Teller as a tortoise? The most banal and boring interpretation would be that Teller had been working at the H-bomb problem for a long time, and it was Ulam — the relative new-comer — had scooped him.

But I can’t help but wonder if there is more to its imagery than that — Gamow’s pen was famously more quick-witted than that. Perhaps there is meant to be a secret clue as to the differences in their approaches?

One stab at it: Teller’s Classical Super involved a propagating thermonuclear reaction in a large mass of fusion fuel — you light one end of a deuterium candle, and the thermonuclear “fire” travels along it. Ulam’s compression scheme (which would be translated into radiation implosion in collaboration with Teller) involved trying to ignite the entire fusion fuel mass all at once, more or less. Teller’s approach is a much slower reaction than Ulam’s; this is part of the reason that Teller’s Classical Super wouldn’t work (the fuel cools too quickly and can’t sustain the temperatures needed for fusion). So Ulam is the fast rabbit, Teller is the slow turtle, and in this instance (unlike Aesop), the rabbit wins the race.

Or perhaps it has something to do with the different geometries? Why does the Teller turtle have three rocks? Is the carrot a reference to the relatively long geometry of the Ulam approach, versus the spherical symmetry of the Alarm Clock design? Is the “P” on Ulam’s hat for his native Poland, or something else?

Are there secrets hidden in Gamow’s humor? Might Gamow be having the last laugh?

  1. Nasser Zakariya, “Making Knowledge Whole: Genres of Synthesis and Grammars of Ignorance,” Historical Studies in the Natural Sciences 42, No. 5 (November 2012), 432-475. []
  2. Robert Christy usually gets the credit for the solid core. It was Teller’s initial idea, but it was Christy who proved it would work. []
  3. George Gamow to Vannevar Bush (12 August 1945), General Records of the Office of Scientific Research and Development, National Archives and Records Administration, RG 227, Box 110, “Security – S-1.” []
  4. This scan comes from the copy reproduced in Peter Galison’s Image and Logic. []

Martian perspectives

Friday, September 28th, 2012

Of the four Hungarian “Martians” who worked the Manhattan Project — so known for their incomprehensible language, their European proclivities, and their exceptional intelligence — Leo Szilard and Edward Teller are tied, in my mind, as the most fascinating and intense personalities. (John von Neumann, the hawkish human computer, comes in a close second. Eugene Wigner, important as he was in the history of nuclear developments, just doesn’t compare to either of the other three when it comes to eccentricity.)

A rare photo of Szilard and Teller together. From a 1960 televised debate they participated in. Source.

Neither need much by means of an introduction on this blog, I don’t think. Leo Szilard was the guy who got the bomb project rolling, but quickly soured on military management. Edward Teller was the future father of the hydrogen bomb, among many other things.

Szilard was one of the strongest advocates of the idea that the atomic bomb should not first be used against an actual civilian target, but should be “demonstrated” in some way, such as on an island or a remote location. He had begun activity on this front as early as the summer of 1942, before the bomb project was truly under way.

His last attempt was a petition he circulated for scientists to sign, with the idea was that it would be presented to the President of the United States. It said, in part:1

We, the undersigned scientists, have been working in the field of atomic power. Until recently we have had to fear that the United States might be attacked by atomic bombs during this war and that her only defense might lie in a counterattack by the same means. Today, with the defeat of Germany, this danger is averted and we feel impelled to say what follows.

The war has to be brought speedily to a successful conclusions and attacks by atomic bombs may very well be an effective method of warfare. We feel, however, that such attacks on Japan could not be justified, at least not unless the terms which will be imposed after the war on Japan were made public in detail and Japan were given an opportunity to surrender.

If such public announcement gave assurance to the Japanese that they could look forward to a life devoted to peaceful pursuits in their homeland and if Japan still refused to surrender our nation might then, in certain circumstances, find itself forced to resort to use of atomic bombs. Such a step, however, ought not to be made at any time without seriously considering the moral responsibilities which are involved. The atomic bombs at our disposal represent only the first step in this direction, and there is almost no limit to the destructive power which will become available in the course of their future development. Thus a nation which sets the precedent of using these newly liberated forces of nature for purposes of destruction may have to bear the responsibility of opening the door to an era of devastation on an unimaginable scale.

The petition continued; you can read the full version here. It was apparently signed by “approximately sixty other scientists” at Chicago.

But Edward Teller was not one of those scientists who signed it.

Edward Teller and Gregory Breit, 1976. (Aside: Breit had been the head of bomb design physics on the Manhattan Project, and was the person who Oppenheimer replaced when he was brought in on the project.) Via the AIP Emilio Segrè Visual Archives.

To many, the idea that Teller would not oppose using the bombs would not be surprising. After all, he was the maker of megatons, right? But this is a misconception, in a sense. Teller was a sensitive soul. He spent a good part of the Cold War trying to argue that he would never have chosen to use the bombs if he had been given a chance. He insisted that his work on the bombs was solely to avoid nuclear war, not encourage it. He was not, I don’t feel, truly bloodthirsty.

Over the later course of his life, Teller occasionally argued that he had opposed the bombing of Hiroshima. This was, as the historian Robert Crease has pointed out, a “truthy” approach — a revisionism based on the history that Teller may have wanted to exist.2

But this is what Teller wrote to Szilard, in early July 1945, a few weeks before the Trinity test:3

Dear Szilard:

Since our discussion I have spent some time thinking about your objections to an immediate military use of the weapon we may produce. I decided to do nothing. I should like to tell you my reasons.

First of all let me say that I have no hope of clearing my conscience. The things we are working on are so terrible that no amount of protesting or fiddling with politics will save our souls.

This much is true: I have not worked on the project for a very selfish reason and I have gotten much more trouble than pleasure out of it. I worked because the problems interested me and I should have felt it a great restraint not to go ahead. I can not claim that I simply worked to do my duty. A sense of duty could keep me out of such work. It could not get me into the present kind of activity against my inclinations. If you should succeed in convincing me that your moral objections are valid, I should keep working. I hardly think that I should start protesting.

This is a strikingly honest way to discuss one’s motivations for working on weapons of mass destruction. Not because of duty — but because of curiosity. Teller worked on the bomb because he thought the bomb was interesting. He wanted to use the bomb because it was the ultimate fruition of that interest. That he could admit such a thing is actually pretty stunning. He did think, though, that morality could stop him from such a project — if he could be convinced.

Teller continued:

But I am not really convinced of your objections. I do not feel that there is any chance to outlaw any one weapon. If we have a slim chance of survival, it lies in the possibility to get rid of wars. The more decisive a weapon is the more surely it will be used in any real conflict and no agreements will help.

Our only hope is in getting the facts of our results before the people. This might help to convince everybody that the next war would be fatal. For this purpose actual combat-use might even be the best thing.

This is an interesting and perhaps not wholly predictable turn, if one subscribes only to a Strangelovian caricature of Teller. Szilard wanted Teller to agree that the bomb should not be used without warning. Teller in turn says that as a scientist who worked on the bomb, he had no responsibility for how it would be used — he was the maker of tools, not the user of them.

A picture of Edward Teller as he probably looked in the early 1940s. Date unknown. From the AIP Emilio Segrè Visual Archives, photo by Francis Simon.

What he felt a responsibility for was in informing people about the bomb, about its consequences, about the reason that it should be a weapon that ends all wars. And, as he argues, “for this purpose actual combat-use might even be the best thing.”

If his responsibility is to show the world what dangers lie ahead, what would be a better way for doing so that utterly destroying at least one city?

Teller concluded:

And this brings me to the main point. The accident that we worked out this dreadful thing should not give use the responsibility of having a voice in how it is to be used. This responsibility must in the end be shifted to the people as a whole and that can be done only by making the facts known. This is the only cause for which I feel entitled in doing something: the necessity of lifting the secrecy at least as far as the broad issues of our work are concerned. My understanding is that this will be done as soon as the military situation permits it.

All this may seem to you quite wrong. I should be glad if you showed this letter to Eugene [Wigner] and to [James] Franck who seem to agree with you rather than with me. I should like to have the advice of all of you whether you think it is a crime to continue this work. But I feel that I should do the wrong thing if I tried to say how to tie the little toe of the ghost to the bottle from which we just helped it to escape.

Teller’s “main point” was that the moral work of the scientists should begin just after the bomb was used. It should be to remove the secrecy and make the facts known, because their special knowledge of how bad things could get — and this is Edward Teller speaking, so we know he was pretty imaginative on this front — gave them the moral imperative to warn the world.4

Teller attempting to make himself understood, in 1963. Via the AIP Emilio Segrè Visual Archives.

In writing his memoirs, some five decades later, Teller noted that,

Rereading the letter, I cannot really agree with the person, my earlier incarnation, who wrote it. I stand fully behind my strong statement against secrecy, but I would no longer say that helping the “ghost” escape was terrible at all. That was our job as scientists, a point that became clearer when I became aware of the great progress that the Soviet Union had made on a nuclear explosive. The responsibility of scientists is to describe and demonstrate what is possible, to disseminate that knowledge as fully as possible, and, with everyone else in our democracy, to share the decisions that are necessarily connected with knowledge.5

Teller’s anti-secrecy stance may seem incongruous given his reputation for nuclear hawkishness. But for Teller, secrecy was something that slowed bomb innovation down — and bomb innovation was the ultimate goal. In such a light, an anti-secrecy hawk makes perfect sense, even if it goes against the conventional political mapping.

Returning to Szilard’s petition five decades later, Teller concluded three things:

First, Szilard was right. As scientists who worked on producing the bomb, we bore a special responsibility. Second, Oppenheimer was right. We did not know enough about the political situation to have a valid opinion. Third, what we should have done but failed to do was to work out the technical changes required for demonstrating the bomb over Tokyo and submit that information to President Truman.6

The first two are fairly straightforward positions, but the last is interesting and provocative. The Manhattan Project scientists spent a huge amount of time thinking up ways to make the bombs more deadly. Whether it was in racing towards a megaton age (Teller’s approach), or calculating the best way to kill Japanese firefighters (Penney’s approach), or — the subject of a future post — a proposal for generating radioactive thunderclouds (seriously), an enormous effort was put into making deadly weapons. Absolutely no technical effort was put into figuring out how one might use the bombs to end the war without bloodshed. The idea was proposed — even urged — but exactly zero effort was put into making it look like a realistic possibility.

The issues raised in this “Martian dialogue” didn’t go away after Hiroshima. If anything, they got more intense, more immediate. What is the responsibility of the tool-maker for his or her tools? What is the responsibility of the scientist to the public? Szilard chose his path and never strayed from it — he never made another weapon again. Teller, if anything, became more extreme on his own path, becoming synonymous with the scientist co-opted by the military-industrial complex, and not just a touch of self-delusion.

  1. Leo Szilard, “Petition to the President of the United States,” (17 July 1945), copy in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 6, Target 5, Folder 76, “Interim Comittee — Scientific Panel.” []
  2. Robert P. Crease, “Biography: Envy and Power,” Nature 468 (2 December 2010), 629-630. []
  3. Edward Teller to Leo Szilard (2 July 1945), copy in the J. Robert Oppenheimer papers (MS35188), Library of Congress, Washington, DC, Box 71, Folder, “Teller, Edward, 1942-1963.” []
  4. Teller forwarded a copy of this letter to J. Robert Oppenheimer, of all people. He prefaced it with a hand-written note, scrawled in an elegant, old-world calligraphy. “What I say is, I believe, in agreement with your views,” he wrote. “At least in the main points.” []
  5. Edward Teller with Judith Schoolery, Memoirs: A Twentieth Century Journey in Science and Politics (Cambridge, Mass.: Perseus Books, 2001), 208. []
  6. Teller, Memoirs, 206. []

In Search of a Bigger Boom

Wednesday, September 12th, 2012

The scientist Edward Teller, according to one account, kept a blackboard in his office at Los Alamos during World War II with a list of hypothetical nuclear weapons on it. The last item on his list was the largest one he could imagine. The method of “delivery” — weapon-designer jargon for how you get your bomb from here to there, the target — was listed as “Backyard.” As the scientist who related this anecdote explained, “since that particular design would probably kill everyone on Earth, there was no use carting it anywhere.”1

Edward Teller looking particularly Strangelovian. Via the Emilio Segrè Visual Archives, John Wheeler collection.

Teller was an inventive, creative person when it came to imagining new and previously unheard-of weapons. Not all of his ideas panned out, of course, but he rarely let that stop his enthusiasms for them. He was seemingly always in search of a bigger boom. During the Manhattan Project, he quickly tired of working on the “regular” atomic bomb — it just seemed too easy, a problem of engineering, not physics. From as early as 1942 he became obsessed with the idea of a Super bomb — the hydrogen bomb — a weapon of theoretically endless power.

(One side-effect of this at Los Alamos is that Teller passed much of his assigned work on the atomic bomb off to a subordinate: Klaus Fuchs.)

It took over a decade for the hydrogen bomb to come into existence. The reasons for the delay were technical as well as interpersonal. In short, though, Teller’s initial plan — a bomb where you could just ignite an arbitrarily long candle of fusion fuel — wouldn’t work, but it was hard to show that it wouldn’t work. Shortly after abandoning that idea more or less completely, Teller, with the spur from Stan Ulam, came up with a new design.

The Teller-Ulam design allows you to link bombs to bombs to bomb. John Wheeler apparently dubbed this a “sausage” model, because of all of the links. Ted Taylor recounted that from very early on, it was clear you could have theoretically “an infinite number” of sub-bombs connected to make one giant bomb.

A few selected frames from Chuck Hansen’s diagram about multi-stage hydrogen bombs, from his U.S. Nuclear Weapons: A Secret History. Drawing by Mike Wagnon.

The largest nuclear bomb ever detonated as the so-called “Tsar Bomba” of the Soviet Union. On 1961, it was exploded off the island of Novaya Zemlya, well within the Arctic Circle. It had an explosive equivalent to 50 million tons of TNT (megatons). It was only detonated at half-power — the full-sized version would have been 100 megatons. It is thought to have been a three-stage bomb. By contrast, the the largest US bomb ever detonated was at the Castle BRAVO test in 1954, with 15 megatons yield. It was apparently “only” a two-stage bomb.

The dropping of the Tsar Bomba, 1961: an H-bomb the size of a school bus.

We usually talk about the Tsar Bomba as if it represented the absolute biggest boom ever contemplated, and a product of unique Soviet circumstances. We also talk about as if its giant size was completely impractical. Both of these notions are somewhat misleading:

1. The initial estimate for the explosive force of the Super bomb being contemplated during World War II was one equivalent to 100 million tons of TNT. As James Conant wrote to Vannevar Bush in 1944:

It seems that the possibility of inciting a thermonuclear reaction involving heavy hydrogen is somewhat less now than appeared at first sight two years ago. I had an hour’s talk on this subject by the leading theoretical man at [Los Alamos]. The most hopeful procedure is to use tritium (the radioactive isotope of hydrogen made in a pile) as a sort of booster in the reaction, the fission bomb being used as the detonator and the reaction involving the atoms of liquid deuterium being the prime explosive. Such a gadget should produce an explosion equivalent to 100,000,000 tons of TNT.2

Teller was aiming for a Tsar Bomba from the very beginning. Whether they would have supported dropping such a weapon on Hiroshima, were it available, is something worth contemplating.

2. Both the US and the USSR looked into designing 100 megaton warheads that would fit onto ICBMs. The fact that the Tsar Bomba was so large doesn’t mean that such a design had to be so large. (Or that being large necessarily would keep it from being put on the tip of a giant missile.) Neither went forward with these.

A US MK 41 hydrogen bomb.

But remember that the original Tsar Bomba was actually tested at 50 megatons, which was bad enough, right? Both the US and the Soviet Union fielded warheads with maximum yields of 25 megatons. The US Mk-41, of which some 500 were produced, and the Soviet  SS-18 Mod 2 missiles were pretty big booms for everyday use. (The qualitative differences between a 50 megaton weapon and a 25 megaton weapon aren’t that large, because the effects are volumetric.)

3. Far larger weapons were contemplated. By who else? Our friend Edward Teller.

In the summer of 1954, representatives from Los Alamos and the new Livermore lab met with the General Advisory Committee to the U.S. Atomic Energy Commission. Operation Castle had just been conducted and had proven two things: 1. very large (10-15 megaton or so), deliverable hydrogen bombs could be produced with dry fusion fuel; 2. Livermore still couldn’t design successful nuclear weapons.

Norris Bradbury, director of Los Alamos, gave the GAC a little rant on the US’s current “philosophy of weapon design.” The problem, Bradbury argued, was that the US had an attitude of “we don’t know what we want to do but want to be able to do anything.” This was, he felt, “no longer relevant or appropriate.” The answer would be to get very definite specifications as to exactly what kinds of weapons would be most useful for military purposes and to just mass produce a lot of them. He figured that the strategic end of the nuclear scale had been pretty much fleshed out — if you can routinely make easily deliverable warheads with a 3 megaton yield, what else do you need? All diversification, he argued, should be on the lower end of the spectrum: tactical nuclear weapons.

Edward Teller and Enrico Fermi, 1951. Courtesy of the Emilio Segrè Visual Archives.

When Teller met with the GAC, he also pushed for smaller bombs, but he thought there was still plenty of room on the high end of the scale. To be fair, Teller was probably feeling somewhat wounded: Livermore’s one H-bomb design at Castle had been a dud, and the AEC had cancelled another one of his designs that was based on the same principle. So he did what only Edward Teller could do: he tried to raise the ante, to be the bold idea man. Cancel my H-bomb? How about this: he proposed a 10,000 megaton design.

Which is to say, a 10 gigaton design. Which is to say, a bomb that would detonate with an explosive power some 670,000 times the bomb that was dropped on Hiroshima.3

If he was trying to shock the GAC, it worked. From the minutes of the meeting:

Dr. Fisk said he felt the Committee could endorse [Livermore’s] small weapon program. He was concerned, however, about Dr. Teller’s 10,000 MT gadget and wondered what fraction of the Laboratory’s effort was being expended on the [deleted]. Mr. Whitman had been shocked by the thought of a 10,000 MT; it would contaminate the earth.4

The “deleted” portion above is probably the names of two of the devices proposed — according to Chuck Hansen, these were GNOMON and SUNDIAL. Things that cast shadows.

The Chairman of the GAC at this time, I.I. Rabi, was no Teller fan (he is reported to have said that “it would have been a better world without Teller”), and no fan of big bombs just for the sake of them. His reaction to Teller’s 10 gigaton proposal?

Dr. Rabi’s reaction was that the talk about this device was an advertising stunt, and not to be taken too seriously.

Don’t listen to Teller, he’s just trying to rile you. Edward Teller: trolling the GAC. A 10,000 megaton weapon, by my estimation, would be powerful enough to set all of New England on fire. Or most of California. Or all of the UK and Ireland. Or all of France. Or all of Germany. Or both North and South Korea. And so on.

“Don’t Fence My Baby In.” Cartoon by Bill Mauldin, Chicago Sun-Times, 1963.

In 1949, Rabi had, along with Enrico Fermi, written up a Minority Annex to the GAC’s report recommending against the creation of the hydrogen bomb. The crux of their argument was thus:

Let it be clearly realized that this is a super weapon; it is in a totally different category from an atomic bomb. The reason for developing such super bombs would be to have the capacity to devastate a vast area with a single bomb. Its use would involve a decision to slaughter a vast number of civilians. We are alarmed as to the possible global effects of the radioactivity generated by the explosion of a few super bombs of conceivable magnitude. If super bombs will work at all, there is no inherent limit in the destructive power that may be attained with them. Therefore, a super bomb might become a weapon of genocide.

If that doesn’t apply to a 10,000 megaton bomb, what does it apply to?

Was Teller serious about the 10 gigaton design? I asked a scientist who worked with Teller back in the day and knew him well. His take: “I don’t doubt that Teller was serious about the 10,000 MT bomb. Until the next enthusiasm took over.” In this sense, perhaps Rabi was right: if we don’t encourage him, he’ll move on to something else. Like hydrogen bombs small enough to fit onto submarine-launched missiles, for example.

It’s hard not to wonder what motivates a man to make bigger and bigger and bigger bombs. Was it a genuine feeling that it would increase American or world security? Or was it just ambition? I’m inclined to see it as the latter, personally: a desire to push the envelope, to push for the bigger impact, the biggest boom — even into the territory of the dangerously absurd, the realm of self-parody.

  1. Robert Serber, The Los Alamos primer: The first lectures on how to build an atomic bomb (Berkeley: University of California Press, 1992), page 4, fn. 2. []
  2. Letter dated October 20, 1944 from James B. Conant to Vannevar Bush, Subject: Possibilities of a Super Bomb. Vannevar Bush-James B. Conant Files, Records of the Office of Scientific Research & Development, S-1, NARA, Record Group 227, folder 3. Quoted from Chuck Hansen, The swords of Armageddon: U.S. nuclear weapons development since 1945 (Sunnyvale, Calif.: Chukelea Publications, 1995), III-17. []
  3. Actually, if you take the Hiroshima yield to be 15 kilotons, it comes out to a nice round 666,666 times the strength of the Hiroshima bomb. But the precision there seemed arbitrary and the symbolism seemed distracting, so I’m relegating this to just a footnote. []
  4. Minutes of the Forty-First Meeting of the General Advisory Committee to the U.S. Atomic Energy Commission, July 12-15, 1954, on p. 55. []