Posts Tagged ‘International control’

Visions

Operation Crossroads at 70

Monday, July 25th, 2016

This summer is the 70th anniversary of Operation Crossroads, the first postwar nuclear test series. Crossroads is so strange and unusual. 1946 in general ought to get more credit as an interesting year, as I've written about before. It was a year in flux, where a great number of possible futures seemed possible, before the apparently iron-clad dynamics of the Cold War fell into place. Crossroads happens right in the middle of the year, and arguably made a pretty big contribution to the direction that we ended up going. Such is the subject of my latest article for the New Yorker's Elements blog, "America at the Atomic Crossroads." Today is the anniversary of the Baker shot, which Glenn Seaborg dubbed "the world’s first nuclear disaster."

America at the Atomic Crossroads

There are a lot of things that make Crossroads interesting to me. The bomb was still in the hands of the Manhattan Project. The Atomic Energy Act of 1946 had not yet been signed into law (Truman would sign it in August, and it would go into effect in January 1947), so the Atomic Energy Commission did not yet exist.

There were these amazing interservice rivalry aspects: the whole backdrop is a Navy vs. Army tension. The Manhattan Project, and the Army Air Forces, had gotten all the glory for the bomb. The Navy didn't want to be left out, or seen as irrelevant. Hence them hosting a big test, and glorying in the fact that a Nagasaki-sized atomic bomb doesn't completely destroy a full naval squadron. (Which was no surprise to anybody on the scientific or military side of things.)

The US had only about 10 atomic bombs at the time. So they expended about 20% of their entire nuclear arsenal on these tests, for relatively little military knowledge gained. The Los Alamos scientists were pretty lukewarm on the whole operation — it just didn't seem like it was getting them much. One wonders, if the bomb had not still be under military control, whether it would have happened.

Photograph of the early mushroom cloud by LIFE photographer Frank Scherschel, with a darkened filter to compensate for the brightness of the flash. Source.

Photograph of the early mushroom cloud of Crossroads Able by LIFE photographer Frank Scherschel, with a darkened filter to compensate for the brightness of the flash. Source.

The first shot, Able, was something of a flub. The fact that it missed its target meant that for public relations purposes it was seen as very ineffective, but it also means that their scientific observations were largely pretty useless. In fact, it missed its target and blew up over one of the main instrumentation ships.

If you read most sources about Crossroads they will say that the source of the Able miss was undetermined, but if you dig down a little deeper you find some pretty plausible solutions (and the reason why the official verdict was "undetermined"). Paul Tibbets, the captain of the Enola Gay and overall head of the atomic delivery group, was pretty clear that it was human error. He said that even before the shot they realized that the crew of the B-29 which dropped it, Dave's Dream, had gotten bad information about the weather conditions, but that they ignored attempts at correction. Tibbets would re-run (with a dummy bomb) the drop with the correct information (and got very close to the target), and also re-ran it with the wrong information (which missed by nearly the same amount as the Able shot). But the USAAF really didn't want to throw their bombardier and plane crew under the bus. So they hinted it might be a problem with the ballistics of the weapon (which were indeed a bit tricky), which infuriated the Manhattan Project officials. Anyway, everyone seems to have been satisfied by just saying they couldn't figure out where the error was. But Tibbets' account seems most plausible to me.1

Crossroads was not secret operation, though there was much classified about it. There were full-spread articles about its purpose in national news publications both before and after its tests. There was probably no test series so publicly conducted by any nuclear power — announced well in advance, covered by the press in real-time, and then heavily publicized afterwards. The fact that the Soviets were invited to a US nuclear test operation (something that would not happen again until the late-1980s) opens up whole other dimensions.

Mikhail Meshcheryakov ("Mike"?) in 1946. At right he is on the USS Panamint, at the Crossroads test. Source: Mikhail Grigorivich Meshcheryakov, on the 100th-anniversary of his birth (Dubna, 2010).

Mikhail Meshcheryakov  in 1946. At right he is on the USS Panamint, at the Crossroads test. Source: Mikhail Grigorivich Meshcheryakov, on the 100th-anniversary of his birth (Dubna, 2010).

The Soviets had three observers at the test: Professor Semyon P. Aleksandrov, a geologist who had worked on the prospecting of uranium; Mikhail G. Meshcheryakov, an experimental physicist; and Captain Abram M. Khokhlov, who attended as a member of the international press corps (he wrote for the Soviet periodical Red Fleet). I found a really amusing little anecdote about the Soviet observers from one of the men who worked the Manhattan Project security detail on Crossroads: Aleksandrov was someone they knew already (he was a "dear old geologist"), but Meshcheryakov was someone "whose name was known, but no one had met personally leading some of us to support he was really an NKVD agent watching Aleksandrov."

I found nothing in the Russian source materials (mentioned below) that would indicate that Meshcheryakov was NKVD, though he was definitely the one who wrote up the big report on Crossroads that was given to Beria, who summarized it for Stalin. Meshcheryakov's report is not among the declassified documents released by the Russians, so who knows if it has any political commentary on Aleksandrov in it. Meshcheryakov ended up having a rather long and distinguished physics career in the USSR, though there is almost no English-language discussion of him on the Internet. Aleksandrov, the "dear old geologist," was actually a major Soviet big-wig in charge of mining operations, which at that time meant he was high in the Gulag system, which was run by the NKVD. For what it's worth.2

Radiation from the Crossroads Baker shot — the radiation went up with the cloud, and then collapsed right back down again with it, resulting in a very limited extent of radiation (the entire chart represents only 4.5 miles on each axis), but very high intensities. Chart source: DNA 1251-2-EX. Collapsed cloud picture source: Library of Congress.

Radiation from the Crossroads Baker shot — the radiation went up with the cloud, and then collapsed right back down again with it, resulting in a very limited extent of radiation (the entire chart represents only 4.5 miles on each axis), but very high intensities. Chart source: DNA 1251-2-EX. Collapsed cloud picture source: Library of Congress.

It was also something of the real birth of "atomic kitsch." There are some examples from before Crossroads, but there is just a real flourishing afterwards. It seems to have taken a year or so after Hiroshima and Nagasaki for enough time to have passed for Americans to start to regard nuclear weapons entirely frivolously. With Crossroads in particular, a deep connection between sex and death (Freud's favorites) circled around the bomb. This is where we start to see the sorts of activities that would later result in the "Miss Atomic Bomb" contests, the release of the really kitchy songs, and, of course, the Bikini swimsuit, named after the "atomic bomb island," as LIFE put it.

The key fulcrum of my article is a meditation on the "crossroads" metaphor, and I should probably note that it was, to some degree, intentional. Vice Admiral William Blandy was reported by the New York Times to have told Congress, that the name was chosen for its "possible significance," which the Times writer interpreted to mean "that seapower, airpower, and perhaps humanity itself — were at the crossroads."3

An unusual color (but not colorized!) photograph of the Crossroads Baker detonation, from LIFE magazine. Source.

An unusual color (but not colorized!) photograph of the Crossroads Baker detonation, from LIFE magazine. Source.

What's interesting to me is that Blandy clearly saw some aspects of the "crossroads," but there was much he couldn't have seen — the atomic culture, the arms race, the contamination, the nuclear fears. He knew that "crossroads" was a good name for what they were doing, but it was an even better name than he could have known, for both better and worst.


As before, I wanted to take a moment to give some credit/citation information that wasn't workable into the New Yorker blog post (where space, and thus academic nicety, is constrained).

The best overall source on Crossroads, which I found invaluable, is Jonathan Weisgall's Operation Crossroads: The Atomic Tests at Bikini Atoll (Naval Institute Press, 1994). Weisgall has been a legal counsel on behalf of the Marshallese, and his book is just a wealth of information. I was pleased to find a few things that he didn't have in his book, because it's a really tough challenge given how much work he put into it. If you find Crossroads interesting, you have to read Weisgall.

Rita Hayworth on the Crossroads Able bomb, "Gilda." Photo by Los Alamos National Laboratory, via Peter Kuran and Bill Geerhart.

Rita Hayworth on the Crossroads Able bomb, "Gilda." Photo courtesy Los Alamos National Laboratory, via Peter Kuran and Bill Geerhart.

Bill Geerhart, who writes the excellent blog CONELRAD Adjacent (and is the one behind the Atomic Platters series of Cold War songs), has done some really wonderful work on the cultural aspects of Crossroads over the years. His posts on the mushroom cloud cake, and his sleuthing regarding the Rita Hayworth connection, are amazing and worth reading in their entirety. Peter Kuran, the visual effects wizard who made the documentary Trinity and Beyond, among other films and works, was very helpful in providing recently-declassified imagery of the Crossroads bombs, including photos (which I first saw on Geerhart's blog) of the Rita Hayworth image on the side of the bomb themselves. (I will be writing more about Kuran and his work in the near future...)

Holly Barker's Bravo for the Marshallese (Thomson/Wadsworth, 2004), is immensely useful as an anthropologist's view of the Marshallese people and their experiences after the test. My invocation of the Marshallese language for birth defects comes directly from Barker's book, pages 81 and 106-107. It is a powerful, disturbing section of the book.

Selection from Life magazine's coverage of Crossroads — two visions of the animal testing. Source.

Selection from Life magazine's coverage of Crossroads — two visions of the animal testing. Source.

Most of the information I got about the Soviet view of Crossroads comes from the multi-volume Atomniy Proekt SSSR document series released by the Russian Federation. I had the full set of these before it was cool, but now Rosatom has put them all online. Scholars have been picking over these for awhile (I have written on them once before), I haven't seen anybody use the particular documents relating to Crossroads before, but you in Tom (Volume) 2, Kniga (Book) 6, the documents I found most useful were 44 (pp. 130-132), 48 (135-136), 50 (137), 76 (184-188), and 106 (246-248). They show the picking of the delegation of observers, brief biographies of the observers, a summary of Meshcheryakov's report (his full 110-page report on Crossroads is not included), and some later aspects of Meshcheryakov's involvement with the planning of the first Soviet nuclear test in 1949 (in which his Bikini experience was offered up as his bonafides).

The other really unusual little source I used for my article is the letter from Percy Bridgman. The letter was sent from Bridgman to Hans Bethe, who relayed it to Norris Bradbury at Los Alamos, who sent it to General Groves. You can read it here. I have been sitting on it for a long time — I almost wrote a blog post about it in 2012, but decided not to for whatever reason. When I worked at the American Institute of Physics I had an opportunity to poke around Bridgman's life and writings a bit, and he's really an interesting character. He was the one at Harvard who served as J. Robert Oppenheimer's physics advisor, and his own work on high-pressure physics not only won him the Nobel Prize of 1946 (which is a nice coincidence for the Crossroads article), but also was used (and is still classified, as far as I can tell) on the Manhattan Project (they seem to have sent him plutonium samples, so you can imagine the kind of work he was doing and why it might still be classified — almost everything on plutonium under high pressures is classified in the United States).

Percy W. Bridgman (L) talking with Harvard colleague (and future Trinity test director) Kenneth Bainbridge, 1934. Source: Emilio Segrè Visual Archives, American Institute of Physics

Percy W. Bridgman (L) talking with Harvard colleague (and future Trinity test director) Kenneth Bainbridge on a Massachusetts beach, 1934. Source: Emilio Segrè Visual Archives, American Institute of Physics.

Bridgman gave a number of talks associated with his Nobel Prize that really tried to get at the heart of what the effects of World War II would be for physics as a discipline. He was very much afraid that Big Science (which hadn't yet been given that name) would really destroy work like his own, which he saw as small-scale, individual, and not focused on particular applications. He was also very interested in topics related to the philosophy of science, something that a lot of modern-day practicing physicists openly disdain. His Wikipedia page gives a nice, brief overview of his life, and even touches on the poignant circumstances of his death.4.

Notes
  1. This is discussed at length in Jonathan Weisgall's Operation Crossroads, pp. 201-204. []
  2. The account of the security officer is Charles I. Campbell, A Questing Life: The Search for Meaning (New York: iUniverse, 2006). This appears to be a self-published memoir, the sort of thing one would never run across without Google Books. On Aleksandrov's Gulag connections (which seem plausible given his uranium connections), see this page on his Hero of Socialist Labor award. One of the few English-language articles on Meshcheryakov is available here. []
  3. Sidney Shallet, "Test Atomic Bombs to Blast 100 Ships at Marshall Atoll," New York Times (25 January 1946), 1. Blandy's full quote on the name from the testimony: "The schedule of target dates for this operation, which will be known by the code word 'CROSSROADS'—and I would like to explain that we have chosen that merely for brevity in dispatches and other communications, and we chose it with an eye to its possible significance—now calls for the first test to be accomplished early in May, over target ships at an altitude of several hundred feed." A lot of the sources about Crossroads include Shallet's bit about "perhaps humanity itself" as a quote of Blandy's, but it's not in the transcript that I can see. Hearing before the Special Committee on Atomic Energy, United States Senate, Pursuant to S. Res. 179, Part 4, 79th Congress, 2nd Session (24 January 1946), on 457. []
  4. The citation for the Bridgman letter is: Percy W. Bridgman to Hans Bethe, forwarded by Norris Bradbury to Leslie Groves via TWX (13 March 1946), copy in the Nuclear Testing Archive, Las Vegas, NV, document NV0128609. []
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What did Bohr do at Los Alamos?

Monday, May 11th, 2015

In the fall of 1943, the eminent quantum physicist Niels Bohr managed a dramatic escape from occupied Denmark, arriving first in Sweden, then going to the United Kingdom. He was quickly assimilated into the British part of the Manhattan Project, then well underway. Bohr's institute in Copenhagen had long been considered the world center of theoretical physics, and in the 1920s, young students from around the world flocked to work with him there. Now, in December 1943, Bohr and his son Aage made their pilgrimage to what was quickly becoming the new, stealth center of nuclear expertise: Los Alamos. At age 59, he would be the oldest scientist on "the Hill," a place where the average age was 29.

Bohr skiing at Los Alamos, January 1945, seemingly without a care in the world. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

Bohr skiing at Los Alamos, January 1945, seemingly without a care in the world. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

This much is a standard part of Manhattan Project lore. Bohr's contributions are usually spoken of primarily in psychological and moral terms. Bohr inspired the physicists to think about the consequences of their work, and laid the seeds of what would become the effort for postwar international control. He also spoke with both Churchill and Roosevelt, ineffectively, about the need to avoid an arms race. Bohr was a notoriously poor oral communicator, typically being barely audible. His deeply alienated and disturbed Churchill, who thought he might be proposing to tell the Soviets about the weapon. He probably just bored Roosevelt.

Some of the stories of his conduct at Los Alamos are adorably absent-minded. One of my favorite memos in the Manhattan Project archives is a February 1944 letter from Lt. Col. John Lansdale, head of MED security, to Richard Tolman, a physicist who was a good friend of the Bohrs. "Subject: Nicholas Baker," it starts out, using Bohr's wartime codename, and explains that in the process of following Bohr around, to make sure he was safe, some, well, deficiencies in his judgment were encountered:

"Both the father and son appear to be extremely absent-minded individuals, engrossed in themselves, and go about paying little attention to any external influences. As they did a great deal of walking, this Agent had occasion to spend considerable time behind them and observe that it was rare when either of them paid much attention to stop lights or signs, but proceeded on their way much the same as if they were walking in the wood. On one occasion, subjects proceeded across a busy intersection against the red light in a diagonal fashion, taking the longest route possible and one of greatest danger. The resourceful work of Agent Maiers in blocking out one half of the stream of automobile traffic with his car prevented their possible incurring serious injury in this instance."

... I understand that the Bakers will be in Washington in the near future, at which time you will unquestionably see them. If the opportunity should present itself, I would appreciate a tactful suggestion from you to them that they should be more careful in traffic.1

Nobel-Prize winning physicist nearly run over by a car, because he treats American streets like paths in a forest, saved from disaster only by a trailing secret agent blocking the road with his car? You can't make this stuff up. These kinds of stories reinforce the playful, harmless, "Uncle Nick" character that Bohr has come to represent in this period.

Bohr and General Groves' personal technical advisor, Richard Tolman, attending the opening of the Bicentennial Conference on "The Future of Nuclear Science," circa 1947. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

Bohr and General Groves' personal technical advisor, Richard Tolman, attending the opening of the Bicentennial Conference on "The Future of Nuclear Science," circa 1947. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

But the truth is a little more complicated. For his part, Bohr would later downplay his role in the actual creation of nuclear weapons. He told another physicist in 1950, for example, that he had spent most of his time while in the United States trying to forestall a nuclear arms race. "That is why I went to America… They didn't need my help in making the atom bomb," he later said.2

Did they need Bohr? Probably not — they probably would have managed well enough without him. But this is an odd standard for talking about one's role in making a weapon of mass destruction. They didn't need almost any individual who worked on the bomb, in the sense that they could have salvaged on without them.3

And not being "needed" does not really get one off the hook, does it? Which gets at what I think is a key point here: in the postwar, Bohr never relied on his contributions to the bomb as a means of claiming moral superiority, responsibility, or political leverage. He was active in attempts to promote international control and avoid an arms race, but he didn't do so in a way that ever owned up to his own role in making the bomb. As a result, a lot of people seem to believe that Bohr didn't really do that much at Los Alamos other than provide the aforementioned moral support and provocative questions.

In fact, Bohr did work on the bomb. And not just on esoteric aspects of the physics, either; one of his role was concerned with the very heart of the "Gadget."

Niels Bohr (r) conversing animatedly with his son Aage in front of a board full of equations. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

Niels Bohr (r) conversing animatedly with his son Aage in front of a board full of equations. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

One of the key parts of the implosion design for the atomic bomb (the same sort of bomb detonated at Trinity and over Nagasaki) is the neutron initiator that sits at the absolute center of the device. It is a deceptively tricky little contraption. At the instance of maximum compression, it needs to send out a small burst of neutrons, to get the whole chain reaction started. It's not even that many neutrons, objectively speaking — on the order of a hundred or so in the first bombs. But conjuring up a hundred neutrons, at the center of an imploding nuclear assembly, at just the right moment, was a tricky technical problem, apparently.

The details are still classified-enough that figuring out exactly what the nature of the problem is proves a little tough in retrospect. In an interview many years later, the physicist Robert Bacher, head of G (Gadget) Division during the war, recalled that for whatever reason, Enrico Fermi had become particularly focused on the initiator as the lynchpin of the bomb, and maybe his own conscience:

I think Fermi began to be very worried about the fact that this terrific thing that he'd sort of been the father of was going to turn into a great big weapon. I think he was terribly worried about it. … I think he [Fermi] was worried about the whole project, not just the initiator. But focusing on the initiator was the one thing that he thought he could look at. The thing really might not work.

And I think he also felt an obligation to take something that was as hare-brained as this was and try to find a way in which it really wouldn't work. So he did look into every sort of thing, and I think every second day or so for a period, I'd see him and he'd come up or he'd see Hans [Bethe] and come up with a new reason why the initiator wouldn't work. …4

Bacher got sick of Fermi's interference, and eventually went to Oppenheimer to complain. Bacher recalled:

I said, "What I'd like to do is, Uncle Nick is here now, and I'd like to go and explain to him about the initiator and say I'd like his advice and counsel on whether he thinks it will work or not. We'll answer any question that he puts to us, that we know the answer to." So we did and he agreed with us and I told him quite frankly, "One of the reasons that we want to do this is that Fermi has so many misgivings about initiators."

So I talked to him for a long while and then he spent about two days with his son Aage going over every single thing that had been done on this business. I saw him after this and he said, "My that's very impressive. I think that will work." I said, "Well now comes the test. Will you talk to Fermi about this? The two of you talk together and give me some counsel of what's up on this?" So he did. And it made a lot of difference to have Uncle Nick talk to Fermi, because he felt that this wasn't somebody you had working on some particular model and so on. It was sort of somebody from the outside, and I think it made Fermi feel a lot happier. And it certainly made it a lot easier for us.5

The initiator that "Uncle Nick" convinced Fermi of, the one that they ended up using in the Trinity and Nagasaki bombs, was the "Urchin."

A schematic of the "Urchin," as imagined by me, based on a postwar British account.

It was a hollow sphere of beryllium, a mere two centimeters in diameter. The inner side of the sphere was machined with grooves, facing inwards. At the center of these grooves was another sphere of beryllium, centered by pins embedded in the outer shell. On both the inner grooves of the outer shell, and the outer surface of the inner sphere were coated with nickel and gold. Onto the nickel of the inner sphere was a thin film of virulently radioactive polonium. Polonium emits alpha particles; in the non-detonated state of the "Urchin," these would be absorbed harmlessly by the gold and nickel. But when the bomb came imploding in around it, the beryllium and polonium would be violently mixed, producing a well-known reaction (beryllium + an alpha particle = carbon + neutron) that produced the necessary neutrons.6

Margrethe and Niels Bohr converse in Copenhagen, 1947, in this extremely rare color photo. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

Margrethe and Niels Bohr converse in Copenhagen, 1947, in this extremely rare color photo. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

"Urchin" wasn't the only initiator design on the table. Fermi apparently favored a design with the codename "Grape Nuts." What was "Grape Nuts"? I have no idea — it's still classified. Presumably these names meant something, since "Urchin" seems to reference the internal spikes. A topic listing for a May 1945 laboratory colloquium at Los Alamos discussed three initiator designs and their creators: "Urchin," attributed to James Tuck and Hans Bethe; "Melon-Seed," attributed to James Serduke; and, lastly, "Nichodemus," attributed to… Nicholas Baker, the codename for Niels Bohr.7

In the recently-declassified Manhattan District History, there are several paragraphs on Bohr. Most of them describe theoretical work he did on the physics of nuclear fission after arriving at the lab, which "cleared up many questions that were left unanswered before." His work affected their understanding the nuclear properties of tamper materials, and he apparently gave them ideas for "new and better methods… of alternative means of bomb assembly." (All of which apparently just pointed to the superiority of implosion, in the end, but still.)

MHD Bohr contributions to bomb

At least one sentence in the Manhattan District History is still completely blacked out. Maybe it refers to the initiator design (which the previous sentence refers to), maybe it refers to something else. It's interesting that seven decades later, something of what Bohr worked on was still considered too classified to reproduce — evidence that Bohr's influence on the bomb was less trivial than he would later make it out to be.8

Why does it matter? In Michael Frayn's Copenhagen, there is, towards the end of the play, an implied asymmetry between Bohr and Heisenberg. Heisenberg is criticized throughout the play for potentially making an atomic bomb for Hitler. The play ultimately says Heisenberg didn't make an atomic bomb in part because he wasn't trying to make a bomb. (It does so with perhaps a little bit too much credence to the "he didn't do it because he was sabotaging it thesis," which I think there is no evidence for and no reason to believe, but anyway.) Driven by his fears, Bohr goes to the United States and actually does work on the bomb, does contribute to the killing of over a hundred thousand people, and so on. And so there is some irony there, where Heisenberg, supposedly the one in a state of moral jeopardy, is the one who actually contributes to the death of no one, where Bohr, supposedly the moral authority, is the one who helps build the bomb.

Bohr with Elisabeth and Werner Heisenberg in Athens, Greece, 1956. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

Bohr with Elisabeth and Werner Heisenberg in Athens, Greece, 1956. Source: Emilio Segrè Visual Archives, Niels Bohr Library, American Institute of Physics.

Do Bohr's contributions to the atomic bomb, however major or minor, weaken his moral authority? I don't really think so. Bohr's strongest and most lasting contribution was putting the bug of international control into the heads of people like Oppenheimer. That bug might have come up on its own (when they learned about Bohr's scheme, Vannevar Bush and James Conant were surprised to find that they had been thinking along almost exactly the same lines, completely independently), but Bohr's influence on openness, candor, the moral obligation of scientists, and so on had a profound effect on postwar political discourse, even if his dreaded arms race was not avoided. In this light, I think Bohr still comes off pretty well, even if the bomb still does contain traces of his fingerprints.

Notes
  1. John Lansdale to Richard Tolman, "Subject: Nicholas Baker," (5 February 1944), Manhattan Engineer District (MED) records, Records of the Army Corps of Engineers, RG 77, National Archives and Records Administration, College Park, MD, Box 64, "Security." []
  2. J. Rud Nielson, "Memories of Niels Bohr," Physics Today 16, no. 10 (Oct. 1963), 28-29. []
  3. I am occasionally drawn into a game of "who is so important that you absolutely couldn't remove them and still expect it to be successful?" I am inclined to think that almost everyone would be more or less replaceable, as individuals, though there are a few whose contributions were so pivotal that removing them would create serious issues. Someday I will post some concrete thoughts on this on this. []
  4. Robert Bacher interview with Lillian Hoddeson and Alison Kerr (30 July 1984), Robert Bacher papers, Caltech Institute Archives, Pasadena, CA, Box 48, Folder 5. []
  5. Ibid. []
  6. Accounts of the exact dimensions of the "Urchin" vary from source to source. John Coster-Mullen's book, Atom Bombs, gives what I find to be convincing evidence that it was 0.8 in./2 cm in diameter. There was 20 curies of polonium deposited in them, and they had to be replaced frequently because of polonium's low half-life. The inner core of the plutonium pit was about 1 in. in diameter, and apparently both the core and the initiator would be expected to expand slightly due to the heat generated by their radioactivity. Apparently James Tuck gave it the name "Urchin," on account of its inner ridges. There is some question as to how the grooves were machined, whether they were pyramids (as in the British account) or ridges (e.g. like a theatre in the round). It's always nice to be reminded that there are still a few secret details out there. []
  7. The list of wartime colloquia comes from the Klaus Fuchs FBI File, Part 49 of 111, available on the FBI's website, starting on page 49 of the PDF. The only other "Nicholas Baker" contribution mentioned in the document is a November 1944 talk on "nuclear reactions of heavy elements and particularly the various results obtained when a neutron comes in contact with heavy nuclei, such as Uranium 238." []
  8. Manhattan District History, Book 8 (Los Alamos Project), Volume 2 (Technical), pages II-2 to II-3. []
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The “Immediate Cessation of Bomb Manufacture” (1946)

Wednesday, February 15th, 2012

For a brief moment after the end of World War II, the fate of the American nuclear arsenal was unknown. The Manhattan Project had built up a sprawling network of laboratories, production facilities, and administrative offices. But the idea of international control was in the air: the idea that there wouldn't be a nuclear arms race at all, that somehow the world would find a way to outlaw proliferation before it even began.

It didn't happen that way, as we well know. Perhaps it was a pipe dream from the start: we also now know that the Soviet Union was fairly dedicated to the idea of getting an atomic bomb of its own, and had been working on it for a number of years at that point. Still, the idea of "international control of atomic energy" is worth taking seriously from an historical mindset: it wasn't at all clear that the Cold War was going to shake out the way it did, in those early days. And much of what was hoped for did eventually take form in the Nuclear Non-Proliferation Treaty -- with the obvious exception that the five big nuclear states got to keep their arsenals.

In this context, today's weekly document is a memo by Richard C. Tolman, the Caltech physicist who had been General Groves' scientific advisor during the war, and who served as the scientific advisor to Bernard Baruch, presenter of the ill-fated "Baruch Plan" for international control to the United Nations.1

A meeting of the UN Atomic Energy Commission in October 1946. Baruch is the white-haired man sitting at the table at right behind the "U.S.A" plaque. At far top-right of the photo is Robert Oppenheimer. Two people above Baruch, in the very back, is General Groves. Directly below Groves is Richard Tolman. British physicist James Chadwick sits directly behind the U.K. representative at the table.

Tolman's memo is an analysis of the question of whether the United States should immediately stop producing more atomic bombs. This sounds like something of a heresy to our modern ears -- the US stop producing atomic bombs, right at the dawn of the Cold War? -- but as Tolman discusses, there were those thought that it might be a little hard to convince the USSR that you're willing to submit to international control restrictions when you're still expanding your nuclear arsenal.

Click image to view PDF.

Tolman was no radical scientist -- he was fairly old, he was politically conservative, and he usually came to the same conclusions as General Groves. His analysis on the cessation issue was also fairly conservative: he pointed out that even if the production of bombs was stopped, there would be no pleasing the Soviets with it, since they would argue that production was going on in secret, or that the US probably already had a big stockpile saved up. (The former point, Tolman notes, might emphasize the importance of inspection, which would become the sticking point of the Baruch Plan. On the latter point, I am not sure whether Tolman knew that that the US stockpile was quite small at that point, but he might have.)

Moreover, Tolman argued that if they made a big deal of stopping, and then later decided to resume production, it would have "a serious adverse effect on international relations."

Still, the fact that Tolman had to go through and make a systematic (and classified) analysis of the issue tells us a lot about the period -- it wasn't an unthinkable idea that the US might have stopped producing nuclear weapons. Within a few years, of course, such an idea would enter into the unthinkable domain, at least for those in positions of influence, and stay there for much of the Cold War.

Notes
  1. Richard C. Tolman to John M. Hancock, "Immediate cessation of bomb manufacture," (4 October 1946), in National Archives, Records of the Office of Scientific Research and Development, RG 227, Files of Richard C. Tolman, S-1 Files, Box 1, "Atomic Energy Commission." []