Posts Tagged ‘Klaus Fuchs’

Redactions

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.

Notes
  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. []
Meditations | Redactions

The Problem of Redaction

Friday, April 12th, 2013

Redaction is one of those practices we take for granted, but it is actually pretty strange if you think about it. I mean, who would imagine that the state would say, “well, all of this is totally safe for public consumption, except for a part right here, which is too awful to be legally visible, so I’ll just blot out that part. Maybe I’ll do it in black, maybe in white, maybe I’ll add DELETED in big bold letters, just so I know that you saw that I deleted it.”

From Hans Bethe's "Memorandum on the History of the Thermonuclear Program" (1952), which features some really provocative DELETED stamps. A minimally-redacted version assembled from many differently redacted copies by Chuck Hansen is available here.

From Hans Bethe’s “Memorandum on the History of the Thermonuclear Program” (1952), which features some really provocative DELETED stamps. A minimally-redacted version assembled from many differently redacted copies by Chuck Hansen is available here.

From a security perspective, it’s actually rather generous. The redactor is often giving us the context of the secret, the length of the material kept from us (a word? a sentence? a paragraph? a page?), and helpfully drawing our eye to the parts of the document that still contain juicy bits. The Onion’s spoof from a few years back, “CIA Realizes It’s Been Using Black Highlighters All These Years,” is only slightly off from the real truth. Blacking something out is only a step away from highlighting its importance, and the void makes us curious. In fact, learning what was actually in there can be quite anticlimactic, just as learning how a magician does their trick (“the guy in the audience is in on the trick”).

And, of course, the way the US declassification system is set up virtually guarantees that multiple, differently-redacted copies of documents will eventually exist. Carbon copies of the same documents exist in multiple agencies, and each agency can be separately petitioned for copies of their files, and they will send them to individual reviewers, and they will each review their guides and try and interpret them. There’s very little centralization, and lots of individual discretion in interpreting the guides.

The National Security Archive recently posted an Electronic Briefing Book that was very critical of this approach. In their case, they pointed out that a given paragraph in a once-secret document that was deemed by the redactor to be completely safe in 2001 was in 2003 deemed secret again, and then, in 2007, reaffirmed safe, and then, in 2012, again secret. “There often seems little logic to redaction decisions, which depend on the whim of the individual reviewer, with no appreciation of either the passage of time or the interests of history and accountability,” writes Michael Dobbs.

This sort of thing happens all the time, of course. In the National Security Archive’s Chuck Hansen papers there are bundles of little stapled “books” he would create of multiply, differently-redacted copies of the same document. They are a fun thing to browse through, viewing four different versions of the same page, each somewhat differently hacked up.

A page from a 1951 meeting transcript of the General Advisory Committee, from the Hansen files. Animated to show how he staples three different copies together. Some documents contain five or more separate versions of each page. For closer inspections of the page, click here.

A page from a 1951 meeting transcript of the General Advisory Committee, from the Hansen files. Animated to show how he staples three different copies together. Some documents contain five or more separate versions of each page. For closer inspections of the page, click here.

In the case of Hansen’s papers, these differences came about because he was filing Freedom of Information Act requests (or looking at the results of other’s requests) over extended periods of time to different agencies. The passage of time is important, because guides change in the meantime (usually towards making things less secret; “reclassification” is tricky). And the multiple sites means you are getting completely different redactors looking at it, often with different priorities or expertise.

Two different redactors, working with the exact same guides, can come up with very different interpretations. This is arguably inherent to any kind of classifying system, not just one for security classifications. (Taxonomy is a vicious profession.) The guides that I have seen (all historical ones, of course) are basically lists of statements and classifications. Sometimes the statements are very precise and technical, referencing specific facts or numbers. Sometimes they are incredibly broad, referencing entire fields of study. And they can vary quite a bit — sometimes they are specific technical facts, sometimes they are broad programmatic facts, sometimes they are just information about meetings that have been held. There aren’t any items that, from a distance, resemble flies, but it’s not too far off from Borges’ mythical encyclopedia.

The statements try to be clear, but if you imagine applying them to a real-life document, you can see where lots of individual discretion would come into the picture. Is fact X implied by sentence Y? Is it derivable, if paired with sentence Z? And so on. And there’s a deeper problem, too: if two redactors identify the same fact as being classified, how much of the surrounding context do they also snip out with it? Even a stray preposition can give away information, like whether the classified word is singular or plural. What starts as an apparently straightforward exercise in cutting out secrets quickly becomes a strange deconstructionist enterprise.

One of my favorite examples of differently redacted documents came to me through two Freedom of Information Act requests to the same agency at about the same time. Basically, two different people (I presume) at the Department of Energy looked at this document from 1970, and this was the result:

1970 AEC declassification guide redactions

In one, the top excerpt is deemed declassified and the bottom classified. In the other, the reverse. Put them together, and you have it all.  (While I’m at it, I’ll also just add that a lot of classified technical data looks more or less like the above: completely opaque if you aren’t a specialist. That doesn’t mean it isn’t important to somebody, of course. It is one of the reasons I am resistant to any calls for “common sense” classification, because I think we are well beyond the “common” here.) In this case, the irony is double, because what they’re de/classifying are excerpts from classification guides… very meta, no?1

What’s going on here? Did the redactors really interpret their guidelines in exactly the opposite ways? Or are both of these borderline cases where discretion was required? Or was it just an accident? Any of these could be plausible explanations, though I suspect they are each borderline cases and their juxtaposition is just a coincidence. I don’t actually see this as a symptom of dysfunction, though. I see it as a natural result of the kind of declassification system we have. It’s the function, not the dysfunction — it’s just that the function is set up to have these kinds of results.

The idea that you can slot all knowledge into neat little categories that perfectly overlap with our security concerns is already a problematic one, as Peter Galison has argued. Galison’s argument is that security classification systems assume that knowledge is “atomic,” which is to say, comes in discrete bundles that can be disconnected from other knowledge (read “atomic” like “atomic theory” and not “atomic bomb”). The study of knowledge (either from first principles or historically) shows exactly the opposite — knowledge is constituted by sending out lots of little tendrils to other bits of knowledge, and knowledge of the natural world is necessarily interconnected. If you know a little bit about one thing you often know a little bit about everything similar to it.

For this archive copy of a 1947 meeting of the General Advisory Committee, all of the raw numbers were cut out with X-Acto knives. Somewhere, one hopes, is an un-mutilated version...

For this archive copy of a 1947 meeting of the General Advisory Committee, all of the raw numbers were cut out with X-Acto knives. Somewhere, one hopes, is an un-mutilated version. In some cases, numbers like these were initially omitted in drawing up the original documents, and a separate sheet of numbers would be kept in a safe, to be produced only when necessary.

This is a good philosophical point, one that arguably is a lot stronger for scientific facts than many others (the number of initiators, for example, is a lot less easily connected to other facts than is, say, the chemistry of plutonium), but I would just add that layered on top of this is the practical problem of trying to get multiple human beings to agree on the implementations of these classifications. That is, the classification are already problematic, and now you’re trying to get people to interpret them uniformly? Impossible… unless you opt for maximum conservatism and a minimum of discretion. Which isn’t what anybody is calling for.

In theory, you can read the classification history of a document from all of its messy stamps and scribblings. They aren't just for show; they tell you what it's been through, and how to regard it now.

In theory, you can read the classification history of a document from all of its messy stamps and scribblings. They aren’t just for show; they tell you what it’s been through, and how to regard it now.

Declassification can be arbitrary, or at least appear arbitrary to those of us locked outside of the process. (It is one of the symptoms of secrecy that the logic of the redactor is itself usually secret.) But to me, the real sin of our current system is the lack of resources put towards it, which makes the whole thing run slow and leads to huge backlogs. When the system is running at a swift pace, you can at least know what it is they’re holding back from you, compare it to other sources, file appeals, draw attention to it, and so on. When it takes years to start processing requests (as is the case with the National Archives, in my experience; it varies a lot by agency), much less actually declassify them, there is a real impediment to research and public knowledge. I’d rather declassification be arbitrary and fast than conservative and slow.

That individual redactors individually interpreting the guidelines according to the standards they are told to use come up with different results doesn’t bother me as much. There is going to be a certain amount of error in any large system, especially one that deals with borderline cases and allows individual discretion. Sometimes you win, sometimes you lose, but it’s being able to play the game in the first place that matters the most to me.

Notes
  1. The document is a discussion of instances in which classification guidelines are based on strict numerical limits, as opposed to general concepts. Citation is: Murray L. Nash to Theos Thomson (3 November 1970), “AEC Classification Guidance Based on Numerical Limits,” part of SECY-625, Department of Energy Archives, RG 326, Collection 6 Secretariat, Box 7832, Folder 6, “O&M 7 Laser Classification Panel. The top was received as the response to a FOIA request I made in 2008, the bottom another one in 2010. Both were part of FOIA requests relating to declassification decisions relating to inertial confinement fusion; the memo in question was part of information given to a panel of scientists regarding creating new fusion classification guidelines. []
Meditations

Narratives of Manhattan Project secrecy

Friday, March 29th, 2013

Secrecy suffused every aspect of the Manhattan Project; it was always in the background, as a context. But it’s also a topic in and of itself — people love to talk about the secrecy of the work, and they’ve loved to talk about it since the Project was made public. In the 1940s there was something of a small industry of articles, books, and clichés regarding how secret the atomic bomb was kept. Of course, the irony is… it wasn’t really kept all that well, if you consider “keeping the secret” to involve “not letting the Soviet Union know pretty much everything about the atomic bomb.” (Which was, according to General Groves, one of the goals.)

It’s easy to get sucked into the mystique of secrecy. One way I’ve found that is useful to help people think critically about secrecy (including myself) is to focus on the narratives of secrecy. That is, instead of talking about secrecy itself, look instead at how people talk about secrecy, how they frame it, how it plays a role in stories they tell about the Manhattan Project.

One of many early articles in the genre of Manhattan Project secrecy: "How We Kept the Atomic Bomb Secret," from the Saturday Evening Post, November 1945.

One of many early articles in the genre of Manhattan Project secrecy: “How We Kept the Atomic Bomb Secret,” from the Saturday Evening Post, November 1945.

My first example of this is the most obvious one, because it is the official one. We might call this one the narrative of the “best-kept secret,” because this is how the Army originally advertised it. Basically, the “best-kept secret” narrative is about how the Manhattan Project was sooo super-secret, that nobody found out about it, despite its ridiculous size and expense. The Army emphasized this very early on, and, in fact, Groves got into some trouble because there were so many stories about how great their secrecy was, revealing too much about the “sources and methods” of counterintelligence work.

The truth is, even without the knowledge of the spying (which they didn’t have in 1945), this narrative is somewhat false even on its own terms. There were leaks about the Manhattan Project (and atomic bombs and energy in general) printed in major press outlets in the United States and abroad. It was considered an “open secret” among Washington politicos and journalists that the Army was working on a new super-weapon that involved atomic energy just prior to its use. Now, it certainly could have been worse, but it’s not clear whether the Army (or the Office of Censorship) had much control over that.

Panel from FEYNMAN by Jim Ottaviani and Leland Myrick.

Panel from FEYNMAN by Jim Ottaviani and Leland Myrick.

We might contrast that with the sort of narrative of secrecy that comes up with regards to many participants’ tales of being at places like Los Alamos. Richard Feynman’s narrative of secrecy is one of absurd secrecy — of ridiculous adherence to stupid rules. In Feynman’s narratives, secrecy is a form of idiotic bureaucracy, imposed by rigid, lesser minds. It’s the sort of thing that a trickster spirit like Feynman can’t resist teasing, whether he’s cracking safes, teasing guards about holes in the fence, or finding elaborate ways to irritate the local censor in his correspondence with his wife. All participants’ narratives are not necessarily absurd, but they are almost always about the totalitarian nature of secrecy. I don’t mean “fascist/communist” here — I mean the original sense of the word, which is to say, the Manhattan Project secrecy regime was one that infused every aspect of human life for those who lived under it. It was not simply a workplace procedure, because there was no real division between work and life at the Manhattan Project sites. (Even recreational sports were considered an essential part of the Oak Ridge secrecy regime, for example.)

So we might isolate two separate narratives here — “secrecy is ridiculous” and “secrecy is totalitarian” — with an understanding that no single narrative is necessarily exclusive of being combined with others.1

"Beyond loyalty, the harsh requirements of security": Time magazine's stark coverage of the 1954 security hearing of J. Robert Oppenheimer.

“Beyond loyalty, the harsh requirements of security”: Time magazine’s stark coverage of the 1954 security hearing of J. Robert Oppenheimer.

But the Feynman approach looks perhaps unreasonably jolly when we contrast it to the narrative of J. Robert Oppenheimer and his students, for whom secrecy became something more sinister: an excuse to blacklist, a means of punishment. Oppenheimer did fine during the Manhattan Project, but the legacy of secrecy caught up with him in his 1954 security hearing, which effectively ended his government career. For his students and friends, the outcomes were often as bad if not worse. His brother, Frank, for example, found himself essentially blacklisted from all research, even from the opportunity to leave the country and start over. (It had a happy ending, of course, because without being blacklisted, he might never have founded the Exploratorium, but let’s just ignore that for a moment.)

For a lot of the scientists involved in the Manhattan Project, secrecy ended up putting their careers on the line, sometimes even their lives on the line. In response to (fairly ungrounded) suspicions about Oppenheimer’s student Rossi Lomanitz, for example, Groves actually removed his draft deferment and had him sent into the dangerous Pacific Theatre. This narrative of secrecy is what we might classically call the “tragic” narrative of secrecy — it involves a fall from grace. It emphasizes the rather sinister undertones and consequences of secrecy regimes, especially during the period of McCarthyism.

The original "best-kept secret" story, released on August 9, 1945 (the day of the Nagasaki bombing).

The original “best-kept secret” story, released on August 9, 1945 (the day of the Nagasaki bombing).

So what other narratives are there? Here is a short list, in no particular order, that I compiled for a talk I gave at a workshop some weeks ago. I don’t claim it to be exhaustive, or definitive. Arguably some of these are somewhat redundant, as well. But I found compiling it a useful way for me to think myself around these narratives, and how many there were:

  • Secrecy is essential”: early accounts, “best-kept secret” stories
  • Secrecy is totalitarian”: secret site participants’ accounts
  • Secrecy is absurd”: e.g. Feynman’s safes and fences
    • Common hybrid: “Secrecy is absurdly totalitarian
  • Secrecy is counterproductive”: arguments by Leo Szilard et al., that secrecy slowed them down (related to the “absurd” narrative)
  • Secrecy is ineffective”: the post-Fuchs understanding — there were lots of spies
  • Secrecy is undemocratic”: secrecy reduces democratic participation in important decisions, like the decision to use the bomb; fairly important to revisionist accounts
  • Secrecy is tragic”: ruinous effects of McCarthyism and spy fears on the lives of many scientists
  • “Secrecy is corrupt: late/post-Cold War, environmental and health concerns

It’s notable that almost all of these are negative narratives. I don’t think that’s just bias on my part — positive stories about secrecy fit into only a handful of genres, whereas there are so many different ways that secrecy is talked about as negative. Something to dwell on.

What does talking about these sorts of things get us? Being aware that there are multiple “stock” narratives helps us be more conscious about the narratives we talk about and tap into. You can’t really get out of talking through narratives if you have an interest in being readable, but you can be conscious about your deployment of them. For me, making sense of secrecy in an intellectual, analytical fashion requires being able to see when people are invoking one narrative or another. And it keeps us from falling into traps. The “absurd” narrative is fun, for example, but characterizing the Manhattan Project experience of secrecy makes too much light of the real consequences of it.

As an historian, what I’m really trying to do here is develop a new narrative of secrecy — that of the meta-narrative, One Narrative to Rule Them All, the narrative that tells the story of how the other narratives came about (a history of narratives, if you will). Part of talking about secrecy historically is looking at how narratives are created, how they are made plausible, how they circulate, and where they come from. Because these things don’t just appear out of “nowhere”: for each of these narratives, there is deep history, and often a specific, singular origin instance. (For some, it is pretty clear: Klaus Fuchs really makes the “ineffective” narrative spring to live; Leo Szilard and the Scientists’ Movement push very hard for the “counterproductive” narrative in late 1945; the “best-kept secret” approach was a deliberate public relations push by the government.)

As a citizen more broadly, though, being conscious about narratives is important for parsing out present day issues as well. How may of these narratives have been invoked by all sides in the discussions of WikiLeaks, for example? How do these narratives shape public perceptions of issues revolving around secrecy, and public trust? Realizing that there are distinct narratives of secrecy is only the first step.

Notes
  1. Both of these might classically be considered “comic” narratives of secrecy, under a strict narratological definition. But I’m not really a huge fan of strict narratological definitions in this context — they are too broad. []
Redactions | Visions

Soviet drawings of an American bomb

Friday, November 30th, 2012

The United States government is pretty gun-shy on publishing drawings of nuclear weapon designs, even very crude ones. When it comes to implosion bombs, this is about all that’s allowed to come out of official sources:

From the 1977 edition of Glasstone and Dolan’s The Effects of Nuclear Weapons. “Then explodes” puts it a little mildly, I think.

Not extremely informative — a ball-within-a-ball — and a heck of a lot less information than you can find from other sources. The reasons for this are ostensibly based in security — terrorists, enemy powers, etc. — though I tend to suspect they are based in the fear of scandal more than anything else. Congressional oversight gets itchy when they see something that looks like a “bomb-making guide,” even when it is well-within the limits of security.1 (The basic implosion idea was declassified in 1951 as part of the Rosenberg trial, though there were knowledgable people arguing for it as early as 1945.)

I find the level of abstraction allowed in such drawings to be a little ridiculous, especially when far more detailed technical information is actually declassified. For reasons that I suspect are deeper than mere policy considerations alone, you can write a lot of things down that you can’t draw, if you’re someone with an actual security clearance. This isn’t totally nonsensical: drawings can make immediately clear lots of things that can otherwise hide in technical descriptions, which is one of the reasons that putative drawings of nuclear weapons are one of the topics that originally drew me to the topic of nuclear secrecy.

We aren’t really talking about blueprints here — these things aren’t usually to scale, they aren’t designed for engineers to use. Even if we were talking about blueprints, there are still quite a few steps in between a drawing of a thing and the thing itself. Drawings of this sort could certainly help an incipient nuclear program, but only in the sense that they can guide research questions or general directions. A drawing of an atomic bomb is not an atomic bomb.

But even though the US is fairly tetchy about its bowdlerized bomb drawings, it does better than most other nuclear states. The United States actually publishes things about their nuclear programs. Though the US has a well-deserved reputation for secrecy, they also have put out tons and tons of technical and non-technical information about how their bombs work(ed), how bombs in general work, technical details about the weapons themselves, and so on. Why? It’s a legacy, perhaps, of the Smyth Report, Atoms for Peace, and other gestures towards the positive role that nuclear information can play in the public sphere.

Ah, but there is one exception: post-Soviet Russia. The people working at Rosatom, the Russian state nuclear agency/corporation, have been publishing impressive amounts of raw historical documents information about the Soviet bomb project, as part of their on-going series Atomnyi proekt SSSR/Атомный проект СССР/USSR atomic project. The series started in 1998, and the early volumes have gotten a lot of good scholarly attention by folks like Alexei Kojevnikov and Michael Gordin, but only very recently did I find that they’ve been still publishing them, and from what I can tell, the newer volumes have not been used too much. The most recent volume that I’ve heard of — volume 3 — was published in 2009. Getting ahold of them is another matter altogether; in the United States, anyway, they’re devilishly hard to find to purchase, and even on Russian websites they are pretty rare. The Library of Congress has the first two volumes in their entirety, and I think I’ve found a source for purchasing the third (supposedly it is on its way), but not without some effort.

Here, for example, is the sort of drawing that the Russians declassified and published in one of the 2007 volumes:

Nuke aficionados will recognize immediately that this is a pretty good drawing of an implosion bomb, especially when compared to the ball-within-a-ball. The labels are pretty straightforward: A– detonator; B– explosive lens (1–Comp. B outer lens, 2–Baratol cone, 3–Comp. B inner lens); C–cork lining; D–aluminum pusher; E–uranium tamper; F–boron plastic shell; G–the Po-Be initiator. The only weird part is that they didn’t label the actual plutonium core itself (the cross-hatched sphere that surrounded the G sphere), but I guess it went without saying. Note also that they’ve indicated how the core can be added in after-the-fact with the removable “trap door” pusher. That’s one of those nice little touches that says, “I am not merely trying to explain an abstract concept, I’m trying to tell you how we might build one of these things.”

But more awesome than the drawing itself — which you can, incidentally, get on a T-shirt, if you’re interested and go for that sort of thing — is its source. It’s from the Soviet archives, part of a report dated January 28, 1946, titled “Notes on the design of the atomic bomb: Description of the construction of the ‘explosion inside‘ type bomb.”2 Get it, “explosion inside”? They hadn’t even formalized their terminology for “implosion” yet and were using a scare-quoted, made-up word in the meantime. As the report makes clear, this is a Soviet description of the American atomic bomb detonated at “Trinity,” based on intelligence received from Soviet spies at Los Alamos. (Other reports refer to Klaus Fuchs directly by name, though I’m not sure if the people drawing up this particular report knew he was the source.)

There is no way in heck that the American government would ever allow the release of so “detailed” a drawing from any source that had access to classified information. Granted, it’s a long way from being a “blueprint” — something the drawing itself acknowledges; the text at the bottom reads “schematic drawing, not to scale” — but it’s still the sort of thing that no weapons lab would want a Congressperson to see them handing out, much less publishing widely. But apparently Rosatom is not as burdened by this — when it comes to publishing pictures of American bombs, anyway!3

Here’s another fan-favorite — a series of drawings breaking the final assembled “Fat Man” bomb into its constituent parts, showing how they call go together, IKEA-style (click any of them to zoom):

The outer casing and the placement of the bomb within it. The caption at bottom says, “Bomb used on Nagasaki (Total weight 10,500 pounds – 4,650 kilograms).” I’m having trouble making out the “note” at the top left but it is seems to be saying something is tentative about the drawing.

The first four “spheres”: 1–initiator, 2–plutonium, 3–tamper, 4–aluminum pusher. Note that the publishers have omitted the exact measurements and replaced them with ellipses. It seems to indicate that the plutonium core is in “3 parts,” which jibes with an earlier post of mine (and indicates that the intelligence source really knew what he was talking about, not that we didn’t already know that). Actually, as is pointed out in the comments, if I had continued translating, I’d see that it says the plutonium must have impurities of only 3 parts per million. Still, a nice little detail.

Spheres 5 and 6: a layer of 32 blocks of chemical explosives, and then a layer of 32 blocks of explosive lenses. The detonator is labeled as a “booster” in English, oddly enough.

Sphere 7: the duraluminum casing, with “holes for detonators.” Comrade Beria likes his details! Compared with the Trinity Gadget.

Lastly, the overall arrangement of the bombs within the casing itself, with its electrical and detonating systems indicated. (You’ll perhaps recognize the first and last images here from another post I did, awhile back, as they are reprinted in a tiny form in another source.)

It’s a veritable nuclear Matryoshka doll, is it not? I wish I could make this stuff up, but I can’t. My favorite part about this document, though, is the fact that so much of the captions are in English — again, as if any indication were needed about where this information was coming from. The document itself was written by Igor Kurchatov for Lavrenty Beria, dated June 4, 1946.

There isn’t anything remotely like a security threat here — you can get better drawings on Wikipedia these days, without the numbers redacted — but to have stuff like this published by an actual nuclear power, based on data they derived in the course of making their own atomic bomb, data taken from a source working in a weapons lab… well, let’s just say, I don’t think it’s going to happen over here anytime soon.

Still, the drawings do have a talismanic power, and the Mandala-like quality of the implosion design doesn’t hurt that. It’s the bomb, right? And yet, it’s really not. It’s a drawing. A technically crude one, albeit more detailed than the other “official” releases. It’s no surprise, I suppose, how easily we get sucked in by the superficially technical — whether it carries any real power or not.

Notes
  1. See, for example, page 70 of chapter 2 of the Cox Report, which criticized Los Alamos for releasing exactly this kind of heavily-sanitized information. []
  2. Заметки о конструкции атомной бомбы. Описание конструкции бомбы типа “взрыва вовнутрь.” []
  3. This reminds me of a joke from the Brezhnev-era USSR that a Russian teacher of mine told me: During a visit to the United States, Premier Brezhnev and President Carter happen to see a protest. “No Carter, No Reagan!” the protesters shouted. “You see,” said Carter, “in our country we have freedom of expression, something you don’t have over in your country.” “Ah, Comrade,” says Brezhnev, “you are wrong! Come over and see!” So they go to Red Square, and indeed, there is a mob of protesters forming, shouting, “Nyet Carter, nyet Reagan!” []
Redactions

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.

Notes
  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. []