Posts Tagged ‘Speculation’

Meditations

Szilard’s chain reaction: visionary or crank?

Friday, May 16th, 2014

Leo Szilard is one of the most fascinating characters of the nuclear age. He was colorful, principled, clever, and often genuinely ahead of his time. And he always shows up early in the story.

Leo Szilard at the University of Chicago in 1954. Source.

Leo Szilard at the University of Chicago in 1954. Source.

Richard Rhodes starts off his The Making of the Atomic Bomb with Szilard’s famous 1933 epiphany:

In London, where Southampton Row passes Russell Square, across from the British Museum in Bloomsbury, Leo Szilard waited irritably one gray Depression morning for the stoplight to change. A trace of rain had fallen during the night; Tuesday, September 12, 1933, dawned cool, humid and dull. Drizzling rain would begin again in early afternoon. When Szilard told the story later he never mentioned his destination that morning. He may have had none; he often walked to think. In any case another destination intervened. The stoplight changed to green. Szilard stepped off the curb. As he crossed the street time cracked open before him and he saw a way to the future, death into the world and all our woe, the shape of things to come. [...]

“As the light changed to green and I crossed the street,” Szilard recalls, “it … suddenly occurred to me that if we could find an element which is split by neutrons and which would emit two neutrons when it absorbs one neutron, such an element, if assembled in sufficiently large mass, could sustain a nuclear chain reaction. “I didn’t see at the moment just how one would go about finding such an element, or what experiments would be needed, but the idea never left me. In certain circumstances it might be possible to set up a nuclear chain reaction, liberate energy on an industrial scale, and construct atomic bombs.” Leo Szilard stepped up onto the sidewalk. Behind him the light changed to red.1

It makes for a good read, though there are disputes about the exact timing of this apparent epiphany. But the basic fact seems to remain: Leo Szilard thought up the nuclear chain reaction over five years before fission was discovered. But he wasn’t taken seriously.

But what did he really propose at the time, though, and not just in retrospect? And should he have been taken more seriously? This is what I want to discuss at some length here, because it is a point of common confusion in a lot of writing on nuclear history.

Szilard had a really interesting idea in the fall of 1933. He took out a patent on it in the United Kingdom, which he required to be made secret. Was Szilard’s idea really an atomic bomb? Was it even a nuclear reactor?  The reason to suspect it was not, on the face of it, is that nuclear fission hadn’t been discovered in 1933. That didn’t happen until late 1938, and it wasn’t announced until early 1939. So what, really, was Szilard’s idea? And why did he file a (secret) patent on it? Was Szilard ahead of his time, or just a crank?

Szilard patent GB630726

Szilard’s 1934 patent is easily available these days, and is worth looking at carefully with an eye to what it both says and doesn’t says. The patent in question is GB630,726: “Improvements in or relating to the Transmutation of Chemical Elements.”2 He filed the application first in late June 1934, updated it in early July, and finalized it by April 1935. The UK Patent Office accepted it as valid in late March 1936, but it was “withheld from publication” at Szilard’s request under Section 30 of the Patent and Designs Act. It was eventually published in late September 1949, 15 years after it had been originally applied for.

The basic summary of the patent is straightforward:

This invention has for its object the production of radio active bodies[,] the storage of energy through the production of such bodies, and the liberation of nuclear energy for power production and other purposes through nuclear transmutation.

In accordance with the present invention nuclear transmutation leading to the liberation of neutrons and of energy may be brought about by maintaining a chain reaction in which particles which carry no positive charge and the mass of which is approximately equal to the proton mass or a multiple thereof form the links of the chain.

This sounds awfully promising, especially when you know what you are looking for. It looks like he’s got the right idea, for a reactor at least: it is patent for creating a neutron-based chain reaction. The reason that neutrons matter is because they lack an electrical charge, and so are not repelled by either the protons or the electrons in atoms. This allows them to penetrate into the nucleus. If they can be linked up so that one reaction produces more reaction, they become a chain reaction. Sounds good, especially if we assume that he means an exponential chain reaction (i.e. each reaction produces more than one subsequent reaction).

But once you get beyond the heading, the details of the patent are, frankly, kind of a confused mess.

Szilard doesn’t actually even state that the chain reaction is going to be produced by neutrons. He hedges his bets there — he describes a neutron, essentially, but generalizes the claim for anything that might behave like a neutron. He calls these “efficient particles” (terrible name), and they have to basically be proton-like in mass but lacking a positive charge. OK, fine. The neutron had just been discovered in 1932, so Szilard is probably thinking that there might be other possible particles out there that acted the same way.

The really weird stuff comes in when he tries to explain how this really works. He defines a chain reaction as when “two efficient particles of different mass number alternate a ‘doublet chain.’” Wait, what? He gives an example:

C(12) + n(2) = C(13) + n(1)
Be(9) + n(1) = “Be(8)” + n(2)

Let’s unpack this. C-12 is Carbon-12, C-13 is Carbon-13, Be-9 is Beryllium-9, “Be(8)” is Beryllium-8, put in quotes here because Szilard know it is pretty unstable (it has an extremely short half-life before it alpha decays). The weird parts are the neutrons — n(1) is just a regular neutron. n(2) seems to be a dineutron, a particle which does exist but was only discovered in 2012, and is certainly not something you can count on. (Szilard never says it is a dineutron, but he implies that you might be able separate n(2) into n(1)+n(1) with another reaction, so it seems to be just that.)

Leo Szilard

So the idea here is that the Carbon-12 absorbs a dineutron, emits a neutron, which is then absorbed by the Beryllium-9, which emits another dineutron. It’s essentially a linear chain reaction, which is not nearly as impressive or fast as an exponential chain reaction. But it would generate some significant energy: calculating the mass deficit of these equations shows that together the net energy release would be around 3.3 MeV, about 100X less than a fission reaction, but is some 330,000X more powerful than the combustion of a single molecule of TNT (~10 eV).3 You’d also maybe get some alpha particles (from the Be(8) decay), but it isn’t going to generate a lot of neutrons or dineutrons (they are going to be eaten up by the reaction itself).

Szilard then notes that maybe there are exponential ways to do this. He suggests that maybe some elements will create multiple neutrons when irradiated with neutrons, e.g.

 Be(9) n(1) = “Be(8)” + n(1) + n(1)

This is a much more exciting possibility, because if every reaction creates the possibility of two more reactions, now we are talking about a reaction that can grow really dramatically. The only problem here is that this reaction seems to be endothermic; if you use E=mc2 to calculate the mass deficit, it comes out as -1.67 MeV. Which ought to be a hint that it isn’t going to work.

The final specification of Szilard’s reactor chamber, which is much more simple in operation than it at first appears.

Szilard then continues by saying that he could make this work well if only he knew what elements might behave this wayWhich is really the crux of it, of course. Szilard has no evidence that any element behaves this way. He has no a priori reason to think any of them do. It’s just a pie-in-the-sky idea: what if there were elements that, when they absorbed one neutron, released two? But Szilard doesn’t dwell on this lack of knowledge. He immediately moves on to how he would design a simple reactor if an element was found. It is nothing terribly interesting: he describes a way to create neutrons and aims them at the reacting substance, then siphons off heat with a heat exchanger and uses it to run a turbine.

In July 1934, Szilard filed an “additional specification” — another patent claim attached to his original patent application. It is an elaboration on the reactor idea. Since he still doesn’t know what fuel would make it run, it’s still not very interesting, other than the fact that he’s put a lot of evident work into figuring out some of the basic properties of the reactor despite not having any clue how its core would actually work. Interestingly he does discuss uranium, but not as a fuel (he thinks it would maybe emit X-rays if he shot high energy electrons at it).

Finally, in April 1935 he filed the last, “Complete” specification. This is more or less identical to a combination of the previous two, except he further makes explicit that he thinks there are going to be “explicit particles” other than neutrons that might work. Basically he asserts that there are probably “heavier isotopes of the neutron”4 and that “It is essential that two isotopes of the neutron should take part in the reaction in order to obtain a chain” (my emphasis). The latter instance shows that he is still not thinking of this quite right — it is not essential that there are multiple isotopes of neutrons.

In his examples, he believes that a “tetraneutron” (i.e. n(4)) exists and can play a role in the reactions. (I know nothing of tetraneutrons, but Wikipedia says that they were claimed to be discovered in 2002 but that the experiments could not be replicated.) Szilard seems to be basing his patent claims here on experiments, but it’s not clear whether he did them or someone else did them, but it seems likely he’s misinterpreting the data. It’s a very odd argument, and he rests quite a lot on it — he seems to think it is far more likely that a nuclear reaction will release bunches of bound neutrons (dineutrons, tetraneutrons) instead of multiples of free neutrons (i.e. as fission does). And then the whole thing was kept secret until 1949 — an awful long time for something that actually reveals nothing of any practical utility, much less military applications.

According to The Collected Works of Leo Szilard, there was an additional claim in his patent application of March 1934 that Szilard had removed from the final specification:

(a) Pure neutron chains, in which the links of the chain are formed by neutrons of the mass number 1, alone. Such chains are only possible in the presence of a metastable element. A metastable element is an element the mass of which (packing fraction) is sufficiently high to allow its disintegration into its parts under liberation of energy. Elements like uranium and thorium are examples of such metastable elements; these two elements reveal their metastable nature by emitting alpha particles. Other elements may be metastable without revealing their nature in this way.5

This is much, much closer to the truth, although it is still somewhat unclear what Szilard really thinks about this. It’s not clear whether he’s describing radioactive decay in the traditional sense, nuclear metastability (which is something different altogether), or something different. Uranium and thorium are radioactive and undergo alpha decay — that, by itself, doesn’t actually indicate that they are good candidates for the kinds of reactions Szilard is thinking about. Szilard doesn’t think they are going to split, he thinks they are going to become artificially radioactive. Not the same thing at all. Still, this is a lot closer to the correct formulation, but we have to read it in the context of everything else he put in the patent.

Anyway, so what’s the verdict? Does the patent describe a bomb? Does it even describe a reactor? Definitely not a bomb, and not really a reactor. Most of Szilard’s energies on the patent are describing something that would, at best, take an input amount of energy and magnify it a bit: you’d use a cathode ray to generate high energy electrons, which would generate high energy neutrons, which would stimulate linear chain reactions that would create radioactive byproducts and release a little energy. Maybe you could keep it self-sustaining but it seems like kind of a long-shot to me.6

An animated version of the above "reactor" operating in a pulsed fashion.

A crudely animated version of the 1934 “reactor” operating in a pulsed fashion, just in case you are having trouble visualizing it.

If you read the patent today with the benefit of hindsight, it’s easy to see where Szilard was right and where he was wrong. There is a germ of rightness in the patent, but it is clouded by a fog of wrongness, or at least confusion. I’m not blaming Szilard for this, of course. Like almost everyone else, he didn’t predict fission. He was ahead of his time, in the sense of anticipating that neutrons in particular were going to be important particles for creating nuclear chain reactions. But he didn’t really understand how it would work. As a result, most of the patent involves describing a device that wouldn’t work. To guess even something right about the future is a large task, even if one gets a few things wrong.

So was Szilard a visionary or a crank? To someone in 1934 or 1935, it would have been completely reasonable to dismiss Szilard’s patent as being too speculative and potentially too wrong (dineutrons, tetraneutrons, etc.) to be worth spending time worrying about. It also isn’t clear it has any real military implications — it isn’t even clear it would work as a power source, much less a weapon. To dismiss Szilard as something of a crank prior to the discovery of fission wouldn’t have been wrong. Szilard’s point of reference here isn’t fission, it’s artificial (induced) radioactivity, which had been discovered by the Joliot-Curies just prior to Szilard’s patent filing. But you can’t make artificial radioactivity work the way Szilard wants it to. I don’t fault anyone for not taking him very seriously at the time — because Szilard’s scheme was missing an absolutely essential component, and in its place there were a lot of incorrect assumptions.

After the discovery of fission in late 1938/early 1939, suddenly it is easy to pick out the visionary aspects of Szilard’s work. It suddenly becomes clear that Szilard was, in fact, a little ahead of the game. That if instead of his plans for beryllium-carbon reactions with neutrons and dineutrons, that a simple, neutron-based, exponential chain reaction would be possible with nuclear fission, and that furthermore it would release a lot more energy a lot quicker than what Szilard had dreamed up in the early 1930s.

Which is a conclusion that complicates the simple visionary/crank dichotomy. Szilard wasn’t really either in my mind. He had a germ of a good idea, but not the whole picture. But when the missing element came along, he was uniquely ready to see how it would complete his original idea. That’s the real story here, the real accomplishment: Szilard didn’t have to play catch-up when fission was announced, because he’d already thought a lot of this through. But that shouldn’t lead us to over-estimate the importance of the original patent work — it wasn’t a bomb, it wasn’t really even a reactor. But it did become a useful framework for thinking about fission, when fission came along.

Notes
  1. Richard Rhodes, The Making of the Atomic Bomb (Simon and Schuster, 1986), 13 and 28. []
  2. It should not be confused with another patent he filed for at the same time with an identical name (GB440,023) which has nothing to do with chain reactions at all.  GB440,023 is basically a patent for producing artificially radioactive elements. The device it describes involves using a cathode tube to generate X-rays, then using the X-rays to stimulate neutron emission in beryllium, and using those neutrons to make artificially radioactive elements through induced radioactivity. It’s not a bad idea — it is now known as the Szilard-Chalmers method and it works. But it’s not a chain reaction at all . Szilard filed a patent for the same idea in the US as well. That Szilard considered it something quite different is also evidenced by the fact that he doesn’t seem to have tried to keep it secret. He references the basic method in GB630,726 as the driver of the reactions in question. []
  3. The beryllium reaction is endothermic but the carbon one is not. []
  4. “I have reason to believe that apart from neutrons which carry no charge and have a mass approximately equal to the proton mass heavier isotopes of the neutron exist which particles carry no charge and has a mass number approximately equal to a multiple of the proton mass.” []
  5. Quoted in Julius Tabin, Introduction, Part V: Patents, Patent Applications, and Disclosures (1923-1959), The Collected Works of Leo Szilard: Scientific Papers (MIT Press, 1972), on 529. []
  6. The neutron multiplication factor, to use modern reactor terminology, seems to me like it is going to be 1 at best, and probably less than that given inefficiencies, losses, etc. One question unasked and unanswered in the patent is how many neutrons he thinks he is going to produce per blast. I think it is easy to overestimate how effective this would be from that point of view. The neutron initiator used in the Fat Man bomb, as an aside, produced only around 100 neutrons on average. This isn’t the same process at all, but in terms of orders of magnitude this is probably not inaccurate when it comes to imagining how many neutrons can be easily stimulated. It is nothing like what a fission chain reaction can generate with its exponential growth. []
Visions

Death dust, 1941

Friday, March 7th, 2014

One of the biggest misconceptions that people have about the Manhattan Project is that prior to Hiroshima, all knowledge of atomic energy and nuclear fission was secret — that the very idea of nuclear weapons was unthought except inside classified circles. This is a side-effect of the narratives we tell about Manhattan Project secrecy, which emphasize how extreme and successful these restrictions on information were. The reality is, as always, more complicated, and more interesting. Fission had been discovered in 1939, chain reactions were talked about publicly a few months later, and by the early 1940s the subject of atomic power and atomic bombs had become a staple of science journalists and science fiction authors.

Campbell's magazine, Cartmill's story. Image source.

Leaks or speculation? Campbell’s magazine, Cartmill’s story. Image source.

John W. Campbell, Jr., was a prolific editor and publisher of science fiction throughout the mid-20th century. In the annals of nuclear weapons history, he is best known for publishing Cleve Cartmill’s story “Deadline” in March 1944, which talks about forming an atomic bomb from U-235. This got Cartmill and Campbell visitors from the FBI, trying to figure out whether they had access to classified information. They found nothing compromising (and, indeed, if you read Cartmill’s story, you can see that while it gets — as did many — that you can make atomic bombs from separated U-235, it doesn’t really have much truth in the specifics), but told Campbell to stop talking about atomic bombs.

But Campbell’s flirtation with the subject goes a bit deeper than that. Gene Dannen, who runs the wonderful Leo Szilard Online website, recently sent me a rare article from his personal collection. In July 1941, Campbell authored an article in PIC magazine with the provocative title, Is Death Dust America’s Secret Weapon?” It’s a story about radiological warfare in what appears to be rather middle-brow publication about entertainment. Click here to download the PDF. I don’t know anything about PIC, and haven’t been able to find much on it, but from the cover one wouldn’t necessarily expect it to be a source for people looking for hard-hitting science reporting — though the juxtaposition of DEATH DUST, “world’s strangest child,” and the “DAY DREAM” woman is a wonderfully American tableau.


PIC magazine 1941 - Campbell - Death Dust - cover

The story itself starts off with what has even by then become a clichéd way of talking about atomic energy (“A lump of U-235 the size of an ordinary pack of cigarettes would supply power enough to run the greatest bomb in the world three continuous years of unceasing flight“), other than the fact that it is one of the many publications that points out that after an exciting few years of talk about fission, by 1941 the scientists of the United States had clamped themselves up on the topic. The article itself admits none of this is really a secret, though — that all nations were interested in atomic energy to some degree. It vacillates between talking about using U-235 as a power source and using it to convert innocuous chemicals into radioactive ones.

Which is itself interesting — it doesn’t seem to be talking about fission products here, but “synthetic radium powders.” It’s a dirty bomb, but probably not that potent of one. Still, pretty exciting copy for 1941. (Campbell would much later write a book about the history of atomic energy, The Atomic Story, where he also spent a lot of time talking about “death dust.”)

The article contains a really wonderful, lurid illustration of what a city that had been sprayed with “horrible ‘death dust’” would look like:

"Even rats wouldn't survive the blue, luminescent radioactive dust. Vultures would be poisoned by their own appetites."

“Even rats wouldn’t survive the blue, luminescent radioactive dust. Vultures would be poisoned by their own appetites.”

The most interesting parts of the article are when it veers into speculation about what the United States might be doing:

With all the world seeking frantically for the secret of that irresistible weapon, what are America’s chances in the race?

It is a question of men and brains and equipment. Thanks to Hitler’s belief that those who don’t agree with him must be wrong, America now has nearly all the first-rank theoretical physicists of the world. Mussolini’s helped us somewhat, too, by exiling his best scientists. Niels Bohr, father of modern atomic theory, is at Princeton, along with Albert Einstein and others of Europe’s greatest.

The National Defense Research Committee is actively and vigorously supporting the research in atomic physics that seeks the final secrets of atomic power. Actively, because the world situation means that they must, yet reluctantly because they know better than anyone else can the full and frightful consequences of success. Dr. Vannevar Bush, Chairman of the Committee, has said: “I hope they never succeed in tapping atomic power. It will be a hell of a thing for civilization.”

Bohr was in fact still in occupied Denmark in July 1941 — he had his famous meeting with Heisenberg in September 1941 and wouldn’t be spirited out of the country until 1943. The photographs identify Harold Urey and Ernest Lawrence as American scientists who were trying to harness the power of atomic energy. Since Urey and Lawrence were, in fact, trying to do that, and since Vannevar Bush was, in fact, ostensibly in charge of the Uranium Committee work at this point, this superficially looks rather suggestive.

PIC magazine 1941 - death dust - scientists

But I think it’s just a good guess. Urey had worked on isotope separation years before fission was discovered (he got his Nobel Prize in 1934 for learning how to separate deuterium from regular hydrogen), so if you know that isotope separation is an issue, he’s your man. Lawrence was by that point known worldwide for his “atom smashing” particle accelerators, and had snagged the 1939 Nobel Prize for the work done at his Radiation Laboratory. If you were going to pick two scientists to be involved with nuclear weapons, those are the two you’d pick. As for Bush — he coordinated all of the nation’s scientific defense programs. So of course, if the US was working on atomic energy as part of their defense research, Bush would have to be in charge of it.

The other illustrations seem to be just generically chosen. They are particle accelerators of various sorts; one cyclotron and many electrostatic (e.g. Van De Graff) accelerators. Cyclotrons did have relevance to isotope separation — they were used to develop the Calutrons used at Y-12 — but the captions don’t indicate that this is why these machines are featured.

I’ve never seen any evidence that Campbell’s story in PIC came to any kind of official attention. Why not? In the summer of 1941, there was a lot of talk about U-235 and atomic energy — and Campbell’s article really isn’t the most provocative of the bunch. There wasn’t any official press secrecy of any form on the topic yet. “Voluntary censorship” of atomic energy issues, which is what would get Cartmill and Campbell in trouble later, didn’t start up until early 1943. Mid-1941 was still a time when a journalist could speculate wildly on these topics and not get visits from the FBI.

The irony is, there were official fears of a German dirty bomb, but they didn’t really crop up until 1942. But the American bomb effort was starting to get rolling in the late summer of 1941. By the end of 1941, Bush would be a convert to the idea of making the bomb and would start trying to accelerate the program greatly. It wasn’t the Manhattan Project, yet, but it was on its way. Campbell’s article was, in this sense, a bit ahead of its time.

A Campbell publication from 1947 — where he apparently has a better understanding of atomic power. Here he seems to have just scaled down a Hanford-style "pile" and added a turbine to it. It took a little more effort than that in reality...

A Campbell publication from 1947 — where he apparently has a better understanding of atomic power. Here he seems to have just scaled down a Hanford-style “pile” and added a turbine to it. It took a little more effort than that in reality…

What I find most interesting about Campbell’s article is that it reveals what the informed, amateur view of atomic energy was like in this early period. Some aspects of it are completely dead-on — that U-235 is the important isotope, that isotope separation is going to matter, that places with particle accelerators are going to play a role, that the acquisition of uranium ore was about to get important, that fears of German use of atomic energy existed. But parts of it are completely wrong — not only would dirty bombs not play a role, he doesn’t seem to understand that fission products, not irradiated substances, would play the strongest role. He doesn’t really seem to understand how nuclear power would be harnessed in a reactor. He doesn’t really seem to get fission bombs at all.

This mixture of accuracy and confusion, of guess and folly, tells us a lot about the state of public knowledge at the time. Atomic energy was a topic, it was an idea — but it wasn’t yet something tangible, a reality. So when people found out, in 1945, that the United States had made and detonated atomic fission bombs, they were primed to understand this as the beginning of a “new era,” as the realization of something they had been talking about for a long time — even if the details had been secret.

Redactions

Heisenberg’s Dresden story: A wartime atomic mystery

Friday, October 11th, 2013

One of the weirdest stories I’ve come across regarding the Nazis and the atomic bomb is the one that the German physicist Werner Heisenberg told at Farm Hall about being asked about an apparent rumor that the United States was planning to use an atomic bomb against Dresden.

The Farm Hall transcripts reports him telling it several times during his internment, and it changed slightly each time he told it. Here’s the first version:

About a year ago, I heard from Segner from the Foreign Office that the Americans had threatened to drop a uranium bomb on Dresden if we didn’t surrender soon. At the time I was asked whether I thought it possible, and, with complete conviction, I replied: “No.

In a later version, he says he replied that it was possible — perhaps a face-saving maneuver, since by the second time Heisenberg tells the story, he has now started to believe that the reports of the atomic attack against Hiroshima were accurate.

My initial inclination is to think of this as strange idle chatter amongst a group of interned German scientists. A little bit of rumor-swapping, bragging about being in-the-know and being someone worth consulting. But I don’t think Heisenberg just made it up. That’s not really his style, I don’t think, and he repeated it several times over the course of their six month stay at Farm Hall.

Physikalische Blaetter, August 1944

Recently, while looking into some other wartime leaks, I came across an interesting follow-up on this story. The leak in question is a weird one and worth sharing. In August 1944, a German science magazine, the Physikalische Blätter (Physical Newspaper/Gazette/Pages), ran a short, anonymous piece titled “Another Utopia“:1

Transocean Service transmits a report cabled to “Stockholm’s Tidnigen” from London: “In the United States scientific research for a new bomb is underway. The material is uranium, and if the forces bound in this element could be liberated, explosive forces of so far unimagined power could be created. A 5-kilogram bomb could made a hole one kilometer deep and with a radius of 40 kilometers. In a circle of 150 kilometers all buildings were be smashed.”2

That’s a pretty weird thing to just appear in a German magazine, no? To save you the effort: their math on the energy release is way off by any measure — the damage radius described is well over 100 megatons, which is around what you’d get if you combined 5 kg of uranium with 5 kg of anti-matter (a pure E=mc2 conversion), much less if it fissioned with perfect efficiency (which would “only” release 85 kilotons).3 Either they’ve carried a few decimal points incorrectly or they’re just really confused. I suspect the latter.

Was this a “legitimate” leak? That is, did it derive from disclosure of confidential information? It’s hard to tell. The fact that it pinpoints the United States as making an atomic bomb out of uranium seems accurate, but everything else seems to be sketchy and confused. It’s true that the plutonium bomb used only around 6 kg of material… but that almost seems like a coincidence given the rest of what they’re talking about here. I’m inclined to file this under “fantastic atomic energy rumors” which were common even before the discovery of fission.

Werner Heisenberg, later in life

Werner Heisenberg, later in life

Anyway. The interesting bit comes 20 years later, in 1964. Physikalische Blätter was (and is) still around, and they ran a story on their wartime leak story. Much of it is repetitive fluff, a by-the-book (for 1964) accounting of Allied and German nuclear research. But along with this, they did attempt to track down the origin of the leak — with no success. But they did decide, thoughtfully, to try and assess the impact of the leak by surveying a few of the Farm Hall physicists to see whether they were aware of the “Another Utopia” story.

Otto Hahn wrote back that he “knew nothing” of the article at the time, and added that while they knew that there were people abroad probably working on the subject of atomic bombs, and that the stopping of all publications about the subject probably indicated the work was secret, that nonetheless they didn’t suspect that the United States would actually be able to produce such weapons in time for use in the war. He then suggested that the Physikalische Blätter should get in touch with Heisenberg, since he was more plugged into such matters than Hahn.4

And they did get in touch with Heisenberg, whose first response was that he hadn’t seen the article, was surprised to hear about it, suspected it was based on “vague rumors,” but said he would love if they sent him a copy so he could evaluate it further.5 They did this, of course, and his second response was the more interesting one. He said that rumors of this sort occurred repeatedly because of articles related to atomic energy that had already been published, and he did not let such rumors occupy him much during the war. But then Heisenberg wrote (my awkward translation — original German is in the footnotes):

Perhaps I should mention here an exception. In the summer of 1944 (probably early July), an aide of Göring’s came to me with a message from a German representative in Lisbon that there was a pronounced American threat against the German government, that an atomic bomb would be dropped on Dresden in the next six weeks if the government did not immediately sue for peace. The exact conditions of where the message came from were not communicated to me. I was asked by Göring’s adjutant if I thought it was possible that the Americans had already created an atomic bomb. I was understandably made very uncomfortable by this question, because of the large responsibility connected to my answer. I said that I thought it was extremely unlikely, but not impossible, for the Americans to have such a weapon at this time, and I tried to explain that the production of the weapon would in any case require an enormous industrial effort, and that I could not imagine that the Americans had already done it.6

And so the Dresden atomic bomb rumor raises its head again, no less confounding than before! But here we have a little more information on the source: it is supposedly from an agent in Lisbon, Portugal. Which is interesting.

General Groves not amused

General Groves is not amused by spies or leaks

Because as Stan Norris communicated to me when I wrote about German espionage efforts, there was a Nazi double-agent in Lisbon who was assigned to learning about the Manhattan Project. Stan has since sent me a “note to file” that General Groves had written about a meeting he had with the Military Policy Committee on June 21, 1944, where he describes this incident and his response to it. In his notes, Groves wrote the following:

This refers to the German agents who came to this country through Portugal, and the messages that were sent back to Germany in their behalf. These people were picked up as soon as they got into the United States and the messages were framed by me. There was considerable argument by my creeps as to these messages. I overruled them and did not deny that certain work was being done. It was pinpointed at certain universities and certain people, none of whom had anything to do with the project. The amount of the work was minimized, and an attempt to convince the Germans that it was an academic effort and that nothing would come of it. The creeps wanted to say that nothing was being done and that checks at various places had indicated that all potential personnel was being used on other work — I think radar.7

Ah, so now this gets really interesting, right? Because this coincides very well with the timing of Heisenberg’s supposed query — apparently originating in Nazi agents in Portugal — regarding whether Dresden would be atomic bombed! (And no, I don’t know why he calls whomever he is talking to “creeps.”)

Obviously I don’t have the whole story here, but the geographical and chronological proximity is a rather impressive overlap, is it not? Could something have gone wrong, or gotten scrambled, in Groves’ attempt to manipulate one of the few German atomic espionage attempts? I.e., Groves had wanted to suggest that the American program was small and unimportant; somebody instead reported back that it was massive and almost ready to go. It seems not impossible, though this is admittedly scant evidence. Either way, it’s clear that Groves would have been mighty mad to find out this question was being asked of Heisenberg.

But, here’s the twist. Arguably the exaggerated outcome would have been (and in fact was!) as good an outcome as Groves’ intended minimization, if not a better one! Heisenberg looked at the six-weeks-to-an-atomic-Dresden claim and said, no way — that doesn’t make any sense. He came away from the whole thing convinced it was just ridiculous wartime nonsense. If the report he had gotten was, “do you believe that the only people working on nuclear fission are a bunch of no-names, instead of Bethe and Fermi and Oppenheimer and Wheeler and all of those other physics luminaries we know the Americans have?,” might that not have raised his suspicions even more?

Of course, that doesn’t explain where Dresden, specifically, would have come into the picture. So there’s still something missing here. And it should be noted that Lisbon was a notorious hub of espionage activity for both sides during the war — so it isn’t necessarily the same guy. So some sobriety intrudes.

Dresden after the firebombing, 1945

Dresden after the firebombing, 1945

Lastly, is it possible the Dresden threat could have been real? The Physikalische Blätter story got picked up by the Washington Post, and they got in touch with Richard G. Hewlett, the Atomic Energy Commission’s official historian. He thought Heisenberg’s story was pretty nuts: “I can’t possibly believe there was an actual threat from the U.S. Government.”8 This was, obviously, because the US was still a year away from an atomic bomb at the time, and the idea of it being some kind of legitimate, diplomatic threat seems pretty out of character. Though do remember that Roosevelt asked Groves about using the bomb against Germany in December 1944 — so maybe, somewhere, this kind of idea was kicking around inside the heads of some people who knew about the Manhattan Project work but didn’t know how close it was to completion — maybe even someone who was working some kind of diplomatic/espionage backchannel. I don’t know.

As it was, Dresden was of course catastrophically attacked. Over the course of three days in February 1945, some 1,250 Allied heavy bombers pounded the city with incendiaries and high explosives, killing well over 20,000 people and burning the heart out of a city that until that point had been spared the horrors of area bombing. Could Dresden have been kept “pristine” on the theory that it might have been a good atomic bombing target, in the same way that Hiroshima, Nagasaki, Kokura, and Niigata had been? The Physikalische Blätter speculated that maybe this was the case, though there is no evidence that supports this conclusion.9 I doubt it, personally — the selection of Dresden as a target has its own trajectory that seems independent of any possible atomic narrative, and the idea that it would have been selected as a possible atomic bomb target as early as the summer of 1944 seems rather far-fetched. It should be noted, as well, that the narrative about the atomic bomb in mid-1960s Germany was very much tinged by the Cold War context; it was a common thread of discussion in both the West and the East that the United States would be willing to throw Germany under the bus if it came to a real confrontation with the Soviets.

Still, it’s an interesting constellation of stories: the leak, Heisenberg’s query, and Groves’ attempt at misinformation. If Groves’ misinformation attempt was really did result in the query to Heisenberg, what tremendous irony would abound. Ironic that Groves’ attempt to minimize the effort would result in a exaggerated interpretation; irony that the exaggerated interpretation would lead to total dismissal by the expert.

Notes
  1. Noch eine Utopie,” Physikalische Blätter 1, No. 8 (1944), 118. I was surprised to find all of PB online and without a paywall. This particular article is appended to a longer report on “Science and War.” []
  2. “Transozean-Innendienst verbreitet eine Nachricht, die sich “Stockholms Tidningen” aus London melden läßt: “In den Vereinigten Staaten werden wissenschaftliche Versuche mit einer neuen Bombe ausgeführt. Als Material dient Uran, und wenn die gebundenen Kräfte in diesem Element frei würden, dann könnten Sprengwirkungen· von bisher nicht geahnter Kraft erzeugt werden. Eine 5-kg-Bombe könnte dann ein Loch von 1 km Tiefe und 40 km Radius hervorbringen. In einem Umkreis von 150 km würden alle festen Gebäude in Trümmer gehen.” []
  3. The rule of thumb is that the completely fissioning of a kilogram of fissile material produces about 17 kilotons of yield. []
  4. “Ich wußte gar nichts von dem Inhalt des Artikels im Augustheft 1944 der Physikalischen Blätter, und so möchte ich daraus schließen, daß er mir auch damals nicht bekannt war. Wir alle waren natürlich während des Krieges der Meinung, daß man im Ausland, vor allem in Amerika, wohl an einer Herstellung von Atombomben arbeiten wird, denn es wurden ja auch in Deutschland Vorversuche darüber gemacht mit dem Versuch der Aufstellung eines Atomreaktors. Und da nach Kriegsanfang alle Publikationen aus dem Gebiete aufhörten, schlossen wir natürlich, daß im Ausland geheime Arbeiten gemacht würden. Andererseits glaubte keiner von uns, daß während der Kriegszeit eine Atombombe fertiggestellt werden könnte. Ich erinnere mich an das Erstaunen, das wir alle hatten, als wir von der Bombe im August 1945 in englischer Gefangenschaft erfuhren. Da Prof. Heisenberg der Vorsitzende des sogen. Uran-Vereins war, also die Arbeiten zur Herstellung eines Kernreaktors geleitet hat, ist wohl Herr Heisenberg die beste Quelle, zu erfahren, ob jemand von uns die Mitteilung in den Phys. Blättern kennt.” Otto Hahn, quoted in E. Brüche, “Was wußte man 1943/44 in Deutschland von der Atombombe?Physikalische Blätter 20, No. 5 (1964), 220-225, on 222. []
  5. “Sie schreiben davon, daß in den Phys. Blättern bereits 1944 eine Notiz über die amerikanischen Versuche mit Atombomben erschienen sei. Dies ist mir völlig neu, aber zugleich interessant und unbegreiflich; denn die ersten amerikanischen Atombombenversuche haben ja bekanntlich im Frühjahr 1945 stattgefunden. Es kann sich also eigentlich nur um ziemlich vage Vermutungen gehandelt haben. Ich wäre Ihnen sehr dankbar, wenn Sie mir eine Kopie jenes Artikels in den Phys. Blättern zukommen lassen könnten; dann kann ich besser beurteilen, ob ich diesen Artikel jemals gesehen habe und wie ich darauf reagiert habe.” Werner Heisenberg, quoted in E. Brüche, “Was wußte man 1943/44 in Deutschland von der Atombombe?” Physikalische Blätter 20, No. 5 (1964), 220-225, on 222. []
  6. “An die von Ihnen erwähnte Notiz in den Phys. Blättern aus dem Jahr 1944 konnte ich mich nicht mehr erinnern, aber Gerüchte dieser Art sind – schon aufgrund des Flüggeschen Artikels in den “Naturwissenschaften” – immer wieder aufgetreten und haben mich daher nicht allzu sehr beschäftigt. Vielleicht sollte ich hier eine Ausnahme erwähnen. Im Sommer 1944 (wahrscheinlich Anfang Juli) kam einmal der Adjutant von Göring zu mir mit der Mitteilung, es sei über die deutsche Vertretung in Lissabon eine amerikanische Drohung gegen die deutsche Regierung ausgesprochen worden, es werde innerhalb der nächsten sechs Wochen eine Atombombe über Dresden abgeworfen werden, wenn die Regierung nicht in irgendeiner Art um Frieden bäte. über den genauen Inhalt der Bedingungen wurde mir nichts mitgeteilt. Ich wurde von dem Adjutanten Görings gefragt, ob ich es für möglich hielte, daß die Amerikaner bereits über eine Atombombe verfügten. Mir war diese Frage begreiflicherweise sehr unangenehm, weil mit der Antwort auf jeden Fall eine große Verantwortung verbunden war. Ich habe dann gesagt, daß ich es zwar für außerordentlich unwahrscheinlich, aber nicht für völlig unmöglich hielte, daß die Amerikaner zu diesem Zeitpunkt über eine solche Waffe verfügten, und habe versucht zu erklären, daß die Herstellung der Waffe auf jeden Fall einen enormen industriellen Aufwand erfordern müßte, von dem ich mir nicht denken könnte, daß die Amerikaner ihn schon geleistet hätten.” Ibid. An article on uranium fission by Siegfried Flügge appeared in Die Naturwissenschaften in June 1939; Heisenberg cites this as the reason for all of the speculation. Flügge himself was asked about the “Another Utopia” article as well and he responded with a diatribe about how nobody credits him for anything. []
  7. Leslie Groves, Notes on the Military Policy Committee of June 21, 1944 (undated, but prior to 1964), Leslie R. Groves Papers, National Archives and Records Administration, RG 200, Entry 7530M, Box 4, “Working Papers.” Courtesy of Robert S. Norris. []
  8. Howard Simons, “Were We Vulnerable: Swedish Report in World War II Tipped U.S. A-Bomb Hand,” Washington Post (27 December 1964), E3. Simons’ story butchers many of the facts, including getting the nationality of Physikalische Blätter wrong (which PB took issue with in its reprinting of it), and even misspells Hewlett’s name. []
  9. “Dresden – Schicksal und Warnung,” Physikalische Blätter 21, no. 4 (1965), 196. []
Redactions

The worst of the Manhattan Project leaks

Friday, September 20th, 2013

We live in an era where the press regularly rejoices in printing “national security secrets,” via leaks, as an evidence of its “watchdog” status. This isn’t exactly a new thing, of course. Press leaks and investigations have been around for quite a long time, and ever since the example of Woodward and Bernstein, this has become the ultimate symbol of journalistic power and access. But it does feel like it has accelerated somewhat in the last decade, both in terms of frequency and magnitude of such “antagonistic leaks” (as opposed to, say, “official leaks” — the kind that are secretly sanctioned for whatever reason). I’ve sometimes heard people suggest that were the press like this during World War II, things like the secret of the atomic bomb could never have been kept as well as they were. And while there is something to that, in the sense that American journalists were far more cooperative and acquiescent during the 1940s, it also projects a rosier picture backwards than ever truly existed. Even during the Manhattan Project, there were copious leaks. Some small, some huge.

Saturday Evening Post, November 1945.

Saturday Evening Post, November 1945 — one of the postwar articles lauding the Manhattan Project as the “best-kept secret,” or, in this case, “the big hush-hush.”

During World War II, the United States had a program of voluntary press censorship, coordinated by the Office of Censorship. It was, as stated, voluntary: there were no fines or threats attached to it, just stern official rebuke. It lacked “teeth.” It worked primarily by the Office of Censorship publicly releasing long lists of prohibited topics, and occasionally trying to squelch violating stories before they were syndicated. As such, it was a little clunky, something that usually went into effect after the fact.

The worst violation came in March 1944. John Raper, a reporter for the Cleveland Press, while on vacation in New Mexico, somehow stumbled upon one of the biggest, most secret stories of the day. Below I reprint the entirety of the article — it nearly speaks for itself, both in its security violations and its strange rambling nature. Some commentary follows; minor comments are in the footnotes. The images have been ordered to correspond with the text, not necessarily how they were laid out on the page.1

1944 - Forbidden City - Masthead

THE CLEVELAND PRESS – MONDAY, MARCH 13, 1944

Forbidden City

Uncle Sam’s Mystery Town Directed by “2nd Einstein”

Jack Raper, Press columnist, has returned to Cleveland following a vacation in New Mexico, where he found the following story.

By JOHN W. RAPER

SANTA FE, N.M. — New Mexico has a mystery city, one with an area from eight to 20 square miles, according to guesses. It has a population of between 5000 and 6000 persons, not more than probably half a dozen of whom can step outside of the city except by special permission of the city boss. He grants permission only in the most exceptional circumstances and under the most rigid conditions. And it is even more difficult for a non-resident to enter than for a resident to leave.2

Commonly known as Los Alamos, the place is a thoroughly modern city. It has fine streets, an electric light plant and waterworks with capacity for a city twice as large as Los Alamos, a service department that really services, public library, high, grade, and nursery schools; recreation centers, hospital, apartment houses, cottages, dance hall, an enormous grocery, refrigeration plant, factories and jail.

If you like mysteries and have a keen desire to solve one, here is your opportunity to do a little sleuthing, and if you succeed in learning anything and then making it public you will satisfy the hot curiosity of several hundred thousand New Mexicans.

But you might as well be informed that you will fail and the chances are thousands to one that you will be caught and will be thrown into the hoosegow or suffer a worse fate.3

A Free Country, But —

Of course, this is a free country and you can go where you please — if you are willing to sleep in the smoking car aisle or breathe the exhalations of your fellow sardines packed in a bus. But forget all about that sort of nonsense.

If you have any idea that you can employ a battery of eminent constitutional lawyers and go into court and that eventually the Supreme Court of the United States will decide the case in your favor if the lower courts decide against you, forget about that, too. you would be wasting your time and burning up any money you paid to the lawyer, for the man who owns this city has too much money and too much power in such a legal action.

This city’s site, or at least part of it, at once time was occupied by a private school for boys,4 and is not far from the village of Los Alamos, which is 53 miles almost due east from Santa Fe, the state capital.5 It is in one of the most interesting sections of New Mexico. It has scenery enough for a whole state — peaks and peaks and more peaks, and cliffs and colors that dim the rainbow.

Not far away are the Indian villages occupied by the finest kind of Indians, intelligent, industrious, friendly, skilled in the production of art objects, many of them graduates of Indian schools.

1944 - Forbidden City - Image 2

Cliff Dwelling Remnants

Within a short distance are the remnants of cliff dwellings, excavated ruins of pueblos centuries old, so old that men who have made scientific studies of them will say, when talking of their ages, “They may be,” “Probably,” “Estimates vary,” “We are pretty certain, but—.”

Shortly after the man who thinks he is going to the mystery city of Los Alamos reaches the level on which it is built, he will see, if he looks into the windshield mirror, a man following him on a motorcycle not many feet behind the car and he will be in the same position when the gate is reached. The instant the car stops there is a man directly in front of it and a man on each side. The three men are in military uniform and each has a rifle.

Then you realize that the owner of this strange city is Uncle Sam and you make no kind of protest and answer questions politely. If you have gone through all of the preliminary red tape previously and have been notified that you will be admitted, the men at the gate will know all about you and there will be little delay after you show the necessary papers.

Escorted by 2 Jeeps

You will be escorted to the office of the man whom you are to meet, escorted by two jeeps, one in front and one behind your car, men in each jeep armed with rifles. En route you will notice that the city is fenced in and that mounted soldiers patrol it and you will see scores of buildings.

When you transact your business you will be carefully escorted out of the city, taking the same route as when you entered. If you are a New Mexican and on your return to your home town it becomes known that you were in Los alamos everybody will ask, “What did you see?” The answer will be, “Nothing.” And if anyone asks, “Did you learn what is going on there?” the answer will be, “I don’t know a bit more about it than I did before I went.” Both answers will be true.

Uncle Sam has placed this in charge of two men. The man who commands the soldiers, who sees that the garbage and rubbish are collected, the streets kept up, the electric light plan and the waterworks functioning and all other metropolitan work operating smoothly is a Col. Somebody.6 I don’t know his name, but it isn’t so important because the Mr. Big of the city is a college professor, Dr. J. Robert Oppenheimer, called “the Second Einstein” by the newspapers of the west coast.7

1944 - Forbidden City - Image 3

Residents Must Stay

Dr. Oppenheimer is a Harvard graduate, attended Cambridge a year, received a Ph.D. from Gottingen University, Germany; is professor of physics at the University of California and the California Institute of Technology, and is a “fellow” of too many organizations to enumerate.8

It is the work of Prof. Oppenheimer and the hundreds of men and women in his laboratories and shops that makes Los Alamos such a carefully guarded city. All the residents will be oblige to remain there for the duration and for six months thereafter and it seems quite probable that many of them don’t know much more about what is being done than you do.9

It is gossip that no one mechanic is permitted to finish a piece of work. He starts to make something and it is passed at a certain point in its production to another, who goes a little further with the work and passes it to another and so on until the article is finished.10

One of the public’s guesses is that nothing but research is done.

Thousands believe the professor is directing the development of chemical warfare, so that if Hitler tries poison gas Uncle Sam will be ready with a more terrifying one.11

1944 - Forbidden City - Image 1

Tell of Huge Explosions

Another widespread belief is that he is developing ordnance and explosives. Supporters of this guess argue that it accounts for the number of mechanics working on the production of a single device and there are others who will tell you tremendous explosions have been heard.12

The most interesting story is that Prof. Oppenheimer is working on a beam that will cause the motors to stop so that German planes will drop from the skies as though they were paving blocks.13

In support of this there are stories of the experiences of automobile drivers in the vicinity of Los Alamos. According to these their radios and motors stopped suddenly at the same instant and after 15 or 20 minutes suddenly began to operate as usual.14

Names of the drivers are frequently given, but when I asked “Did any of them tell you, or did you get it secondhand?” the answer invariably was, “Well, he didn’t tell me. A friend of mine told me about it.”

And if you say, “Did you ask your friend if the driver who had the experience told him?” The answer is generally, “Well, I didn’t ask that question.”

One of these days Prof. Oppenheimer may tell the newspapers about what he has done at Los Alamos, there may be another now-it-can-be-told book or the secretary of war may hand out the report made to him. And who knows but that the eminent physicist may deliver an address at the Cleveland City Club or the Rotary Club?

If you’d rather see it in the original spread, uploaded here is my copy of it from the archives. Note the original is a photostat and has black/white reversed, which is why it is a bit washed out after photographing (shop talk: it is very hard to photograph old photostats because they are on glossy paper and thus reflective, so you have to take pictures of them under shadows).

Why do I consider this the worst? Not because it says, in any straight terms, that atomic bombs are being made. But look at the suggestions it is giving to potential spies:

  • It identifies (with some geographical error) the name and location of an obviously classified scientific/military facility
  • It gives an approximate and plausible size of the facility, which gives some hint of its importance
  • It emphasizes the amount of compartmentalization going on at the facility, which again hints at its importance
  • It correctly identifies the scientific director, which to an observed eye would narrow it down to something relating to theoretical physics
  • It reports local accounts of explosive testing on site

If I were a spy thinking about nuclear weapons, I would find that a pretty interesting combination of things, and worth following up on. Of course, it also has a healthy dose of confusion, nonsense, and just plain silliness mixed into it. But even a ray gun that stopped airplanes, or a chemical weapons plant, might be of interest to enemy spies. (Much less Allies who you don’t want snooping around, like the Soviets.) The article has just enough ring of authenticity to it to suggest that something serious was going on at Los Alamos — which makes it much more dangerous than something that was wilder yet potentially closer to the truth.

General Groves — not amused.

General Groves — not amused.

The Manhattan Project security apparatus was not amused. Col. Ashbridge, the military head of Los Alamos, sent a copy to Groves a few days after it was published, noting that he had heard that Groves was already aware of it and that it had been shown to Oppenheimer. Ashbridge wrote:15

We are naturally much perturbed about it and Major [Peer] de Silva [Los Alamos security head] is preparing a memorandum to Lt Col [John] Lansdale [Manhattan Project security head] as to the source of the data collected by the reporter while vacationing in Albuquerque and Santa Fe. There are many rumors around town about this project since thousands of construction workers from this vicinity have been employed at Los Alamos, many of our personnel go into town for shopping and weekends, and Dr. Oppenheimer’s name is fairly well known in Santa Fe.

In discussing this with Major de Silva, he indicated that he felt the “leak” was not something we could have prevented, but that the reporter had doubtless picked up some local gossip, and put it together with information on Dr Oppenheimer in “Who’s Who.”

The late A.J. Connell [director of the Los Alamos Ranch School] informed me several months ago that everyone in Santa Fe knew some sort of scientific project was underway at Los Alamos, but that curiosity had died down when no one found out anything more after several months, and they just accepted us without trying to guess what was done.

The action of the newspaper in printing such an article shows a complete lack of responsibility, compliance with national censorship code and cooperation with the Government in keeping an important project secret. It is hoped that some steps can be taken to deny the paper certain privileges as a result of their disclosure of this project in such an article.

So what did Groves end up doing? First he made sure that it wouldn’t spread further — he put the kibosh on any follow-up stories or further syndication. Time magazine was going to write a follow-up regarding West Coast atom smashing work, but the Office of Censorship stopped them. Then he had the reporter investigated and interviewed. For awhile he thought about getting Raper drafted to the Pacific Theatre — a rather bloodthirsty approach to the problem. He relented on this when, as it turned out, Raper was in his sixties. Not exactly Army grunt material.16

Did the Axis powers notice this? If they did, they don’t seem to have done much with it. Which highlights an important aspect of Manhattan Project secrecy, in a way: how lucky it was. There were a tremendous number of puzzle pieces out there for an enemy power to notice and put together regarding the bomb effort. It was not quite so perfectly secret as we often talk of it as being. We know it was possible to put some of the pieces together, because the Soviets did it, and even a few others did it. (I’m in the process of writing an article about some of the successful efforts, so more on that later.) Groves wanted a hegemonic, all-encompassing, all-controlling secrecy regime. Understandably, he couldn’t accomplish that — but he pulled off just enough that, with a bit of luck, the project stayed more or less below the water line.

Notes
  1. Source: John W. Raper, “Forbidden City,” (13 March 1944) The Cleveland Press. Photostat copy in Manhattan Engineer District records, Records of the Army Corps of Engineers, Record Group 77, National Archives and Records Administration, Box 99, “Investigation Files.” []
  2. While entry to Los Alamos was heavily restricted, many more than “half a dozen” people were allowed to leave. []
  3. This guy is impressively flip, eh? []
  4. The Los Alamos Ranch School. []
  5. Los Alamos is 35 miles northwest of Santa Fe. []
  6. Probably a reference to Col. Whitney Ashbridge, the post commander of the Los Alamos site. Ashbridge had replaced the original military head, Col. John Harman, because the latter had difficulty getting along with the scientists. Ashbridge himself was replaced by Col. Gerard Tyler in late 1944, after Ashbridge’s health began to fail because of the strain brought on by the job. See Vincent C. Jones, Manhattan: The Army and the Atomic Bomb (US Government Printing Office, 1985), 486, 497-498. []
  7. Something of an exaggeration, of course — Oppenheimer’s purely scientific achievements never rivaled Einstein’s. Still, there is some irony in the fact that Oppenheimer would in the postwar take a position as the Director of the Institute for Advanced Study, in the Princeton, New Jersey, and as such effectively become Einstein’s boss. For more on Einstein and Oppenheimer, see S.S. Schweber, Einstein and Oppenheimer: The Meaning of Genius (Harvard University Press, 2010). []
  8. Manhattan Project security speculated that this information came from Oppenheimer’s Who’s Who entry. No comment on whether this “fellow” was a “fellow traveler” or not… []
  9. Again, I don’t really know where he gets this “sealed in” argument from. It is not correct. But it is true that most of the residents were not aware of the final goal of the project. []
  10. This is an exaggeration of the compartmentalization policy, but not so off the mark. Henry Smyth once joked to the New Yorker that because he ran two different divisions in the project, he was not allowed by rules to talk to himself. []
  11. Not entirely off the mark, either in actual purpose or analogy. The first Los Alamos-like installation that I have heard of dates from World War I, the so-called “Mousetrap” factory in Cleveland, where Lewisite (an arsenic-based chemical weapon) was produced. James B. Conant worked on that project. []
  12. Very, very close to the mark. The explosives heard may be related to the implosion studies, which had begun in the summer of 1943. []
  13. The idea of motor-stopping beams is one that pops up in numerous places during speculation about enemy science during World War II. I have even read stories that have said the technology was obvious, though I have no idea what it might have been. []
  14. No, not an electromagnetic pulse. Aside from the fact that no nuclear weapons had been set off by March 1944, the nuclear EMP at ground level is a very short-range effect compared to the blast effects, and if your car was really damaged by an EMP it would not start back up again in 15 minutes. []
  15. Whitney Ashbridge to Leslie R. Groves (18 March 1944), Manhattan Engineer District records, Records of the Army Corps of Engineers, Record Group 77, National Archives and Records Administration, Box 99, “Investigation Files.” []
  16. Patrick S. Washburn, “The Office of Censorship’s Attempt to Control Press Coverage of the Atomic Bomb During World War II,” Journalism Monographs 120 (1990), 1-43, on 11-12, and 37 fn. 43. See also Robert S. Norris, Racing for the Bomb: General Leslie R. Groves, The Manhattan Project’s Indispensable Man (Steerforth Press, 2002), 275-276. []
Redactions

What did the Nazis know about the Manhattan Project?

Friday, September 13th, 2013

The primary motivation of much Manhattan Project secrecy was to keep the Germans from finding out that the United States and United Kingdom were feverishly working on developing nuclear weapons. So it seems a pretty sensible question to ask: Did it work? That is, did the secrecy keep the Germans from knowing about Allied progress on the bomb?

Strangely enough, I wasn’t able to find much of anything published on the question of what knowledge, if any, the Axis powers had about the atomic bomb. The fact that they didn’t develop one themselves is not strong evidence — it just might mean that such knowledge was very limited, or not believed, or not shared correctly. I can’t do the topic the justice it deserves, because I’m not conversant enough with the sources of Axis foreign intelligence, but I can present some thoughts and intriguing little discoveries on here regarding the German program. If anyone has further thoughts, or evidence, I’m all ears.

Farm Hall, the British country estate.

Farm Hall, the British country estate.

Where might we look for such evidence? The major, obvious source are the Farm Hall transcripts. Farm Hall was the British country manor where ten of Germany’s nuclear scientists were kept for six months. Their conversations were bugged. They were, on August 7th, told about the atomic bombing of Hiroshima, and the transcripts were carefully probed at the time, and many times since, for any insight given into what the German nuclear weapons program had been at the time. The transcripts are a notoriously tricky primary source, in part because the original German copies have apparently since been lost (so we only have an English translation), and because there are some indications that the scientists were aware they were being bugged. Separately there is the psychological complexity of the issue, as the scientists were trying to come to terms with themselves, an imagined German public, and an imagined world public regarding their participation (or lack thereof) in making nuclear weapons for Hitler.1

With that said, is there anything in the Farm Hall transcripts that enlightens us one way or the other? The most significant part is that the announcement of Hiroshima, first given orally, “was greeted with incredulity.” See, for example, this sort of exchange:

HEISENBERG: Did they use the word uranium in connection with this atomic bomb?

ALL: No.

HEISENBERG: Then it’s got nothing to do with atoms, but the equivalent of 20,000 tons of high explosive is terrific. [...]

GERLACH: Would it be possible that they have got an engine [reactor] running fairly well, that they have had it long enough to separate “93”? [neptunium]

HAHN: I don’t believe it.

HEISENBERG: All I can suggest is that some dilettante in America who knows very little about it has bluffed them in saying: “If you drop this it has the equivalent of 20,000 tons of high explosive” and in reality doesn’t work at all. [...]

WEIZSÄCKER: I don’t think it has anything to do with uranium. [...]

HAHN: If they really have got it, they have been very clever in keeping it secret.2

All of which has been sometimes taken as pretty strong evidence that these guys didn’t know much about the Allied project. But a closer reading is less clear, because, among other things, not everyone is participating in this discussion. One of the many problems with the German nuclear program was a lack of coordination and a lack of shared knowledge. That Otto Hahn knew nothing of it seems entirely believable, but irrelevant, since he wasn’t really working on the nuclear program in any kind of military capacity. Werner Heisenberg and Carl Friedrich von Weizsäcker worked together so it makes sense that they would be on basically the same page. But what about the others? 

Farm Hall mugshots: Werner Heisenberg, Carl Friederich von Weiszäcker, Otto Hahn, and Kurt Diebner.

Farm Hall mugshots: Werner Heisenberg, Carl Friederich von Weiszäcker, Otto Hahn, and Kurt Diebner.

Walter Gerlach was in a more administrative role, so one might imagine he would know of any foreign intelligence on the subject. He speaks very little in this part of the transcript, only the question about reactors, and he is not one of the outright initial doubters. Asking whether they could have had reactors does not indicate that he was unaware of an Allied bomb project in general, especially given the compartmentalization of the Manhattan Project. He does, much later in the transcript, apparently express private surprise with Heisenberg that “they had known nothing about the preparations that had been made in America,” though. And what of Kurt Diebner? Diebner ran the other major research wing of the German nuclear program, separate from Heisenberg. He says almost nothing in this section of the transcript, only noting that “there is also a photochemical process” for enriching uranium. Again, this tells us nothing about what he knew.3

Probing the transcript further, we find a few other odd exchanges:

HAHN: From the many scientific things which my two American collaborators sent me up to 1940, I could see that the Americans were interested in the business. 

WEIZSÄCKER: In 1940 van der Grinten wrote me, saying he was separating isotopes with General Electric.

HARTECK: Was van der Grinten a good man?

WEIZSÄCKER: He wasn’t really very good but the fact that he was being used showed that they were working on it.4

I read these as Hahn and Weizsäcker trying to recall whether they had any indication of Allied interest. Considering their only memories are from 1940 (before the Manhattan Project really began), they are actually a good indication that they did not have any truly specific intelligence.

Heisenberg three times tells a story about being contacted from someone in the German Foreign Office about uranium questions:

HEISENBERG: About a year ago, I heard from Segner [probably Sethke] from the Foreign Office that the Americans had threatened to drop a uranium bomb on Dresden if we didn’t surrender soon. At the time I was asked whether I thought it possible, and, with complete conviction, I replied: “No.”5

Now that is a strange story. I have no idea what this Sethke would have been referring to — some strange rumor. Whether it is just nonsense, or based on some actual intelligence, it’s impossible to know from just this snippet. Later, when Heisenberg tells another version of the story (this time making his answer that it was “absolutely possible”), he specifies it was in July 1944 and that it was “a senior SS official” who had asked him about the bomb.6

More Farm Hall mugshots: Walter Gerlach, Paul Harteck, Max von Laue, Karl Wirtz.

More Farm Hall mugshots: Walter Gerlach, Paul Harteck, Max von Laue, Karl Wirtz.

There is also one small exchange before the German scientists were told about Hiroshima. On August 4th, Heisenberg, Gerlach, and Hahn had this exchange:

GERLACH: The [British] Major [Rittner] asked me what we had known about scientific work in enemy countries, especially on uranium. I said, “Absolutely nothing. All the information we got was absurd.”

HEISENBERG: In that respect one should never mention any names even if one knew of a German who had anything to do with it.

GERLACH: For instance, I never mentioned the name of that man Albers (?). The “Secret Service” people kept asking me: “From whom did you get information?” and I always replied: “There was an official in Speer’s ministry and in the Air Ministry who gave it out officially.” I did not say it was Albers (?) who did it.

HEISENBERG: I had a special man who sent me amazing information from Switzerland. That was some special office. Of course I have burnt all the correspondence and I have forgotten his name.

HAHN: Did you actually get any new information from him?

HEISENBERG: At that time I always knew exactly what was being discussed in the Scherrer Institute regarding uranium. Apparently he was often there when Scherrer lectured and knew what they were talking about. It was nothing very exciting but, for instance, he once reported that the Americans had just built a new heavy water plant and that sort of thing.7

And there it ends. Other than the mention of heavy water, it is too vague to make much sense of. (The Manhattan Project built several heavy water plants are part of what they called the P-9 Project, as part of their “leave no stone unturned” approach. They upgraded an existing ammonia plant at Trail, British Columbia to produce heavy water, and built three supplementary facilities at military sites in West Virginia, Indiana, and Alabama.)

After the scientists had heard the official BBC radio announcement, they all began to believe it was true, and worked out fairly quickly how it probably would have worked (though even there, they were still impressively confused at times) and famously hashed over why they didn’t get one made. No further invocations of foreign information or intelligence were made that I found.8

My overall impression is that for the bulk of the ten scientists, the Allied atomic bomb probably did come as a genuine surprise of immense magnitude. But there are enough hints there to suggest that various bits and pieces were out there amongst their foreign intelligence officials, whether they shared all of that with the scientists or not. And as we’ve see in the Soviet case, just because the spies know something doesn’t mean it percolates back to the scientists working on it — the use of foreign intelligence is not a straightforward operation. And there are several scientists whose reactions were not individually recorded (e.g. Diebner). Of the scientists who talked a lot, they seemed genuinely clueless about what the Americans had done, but not all of them talked.

Are there any other indications? One thing that one finds on the Internet are assertions that the last attempt by the Nazis to deposit saboteurs on American soil, Operation Elster (Magpie), was supposedly aimed at sabotaging the Manhattan Project. Like all such Nazi efforts, the saboteurs in question were rounded up pretty quickly. Were they really targeting the Manhattan Project? I suspect not. The sources that give such information all seem to trace back to a postwar memoir of one of those captured. David Kahn has written that he thinks it is nonsense; I am inclined to agree.9) The idea that a single pair of spies would be sent to gain information on, much less sabotage, the Manhattan Project is too silly to be believed without corroborating evidence.

J. Edgar Hoover, 1941. Source.

J. Edgar Hoover, 1941. Source.

But there is one last interesting source that I stumbled across. In early February 1945, J. Edgar Hoover wrote a memo to Harry Hopkins (one of Roosevelt’s closest aides) explaining that the FBI had information that indicated German interest in atomic matters. Specifically, Hoover wrote:

As you are well aware, the Army for the past two years has been vitally interested in a highly secret project for the development of an atomic explosive. [...]

Recently, in connection with the operation of a radio station by a German agent under control of the Federal Bureau of Investigation but which station the Germans believe to be a free station, an inquiry was received from Germany containing the following questions regarding the status of atomic explosive experimentation in the United States:

First, where is the heavy water being produced? In what quantities? What method? Who are users?

Second, in what Laboratories is work being carried on with large quantities of uranium? Did accidents happen there? What does protection against Neutronic Rays consist of in these laboratories? What is the material and the strength of coating?

Third, is anything known concerning the production of bodies or molecules out of metallic uranium rods, tubes, plates? Are these bodies provided with coverings for protection? Of what do these coverings consist?10

Now this looks like a legitimate technical intelligence inquiry. These are very specific questions regarding reactor construction. Not necessarily bomb construction, mind you. But it does look like someone working on reactors passed some questions up the chain of command. (The fact, incidentally, that this came to the FBI from a double-agent is also telling — the German foreign intelligence networks were notoriously compromised, yet another reason they missed so much.)

The questions reveal, though, that whomever asked them did not realize that the Americans had already been building massive, industrial-sized, carbon-moderated (not heavy water!) nuclear reactors in Hanford, Washington. Note the lack of any queries regarding uranium enrichment. Note that the questions are narrowly technical, the kind of questions you would ask if you are trying to build your own reactor, not ferret out a clandestine bomb program.

That the Germans were asking such basic, ignorant questions so late in the game — the Red Army was bearing down on Berlin and their atomic program, like so many other things, was in a tizzy11is perhaps the greatest indication that they knew very little about the American Manhattan Project indeed. That they were asking questions at all is not surprising, but the lateness perhaps is. The Soviet physicist Georgii Flerov figured out that the Americans must be working on a nuclear program in 1942, when he noticed that nobody was publishing on the subject — specifically, that nobody was citing his publication on the spontaneous fission of uranium-238. One wonders why the Germans were less observant of this fact, especially given the amount of “brain drain” their own institutes suffered.12 They also appear to have missed or misunderstood all of the various leaks, accidental disclosures, and other signs that drove General Groves and others involved with Manhattan Project security so mad. Many pieces were there for them to put together, but they didn’t solve the puzzle.13

Allied troops disassembling the German experimental research reactor at Haigerloch.

Allied troops disassembling the German experimental research reactor at Haigerloch as part of Alsos.

Lastly, we have the take of Samuel Goudsmit, the head of the Alsos expedition. In an unpublished memorandum written in late 1945, claimed that the Alsos investigation into the German work had shown that “the enemy was equally ignorant of Allied scientific and technical work,” though notes that in 1939, a team of three Germans were sent to the USA to learn about American interest in uranium research. (This was well before there was much American interest in such.) As he was prone to do, Goudsmit generalized greatly from this, assuming that scientific and technical intelligence was too difficult to pick up during that war. The Soviets, as always, proved an important exception to Goudsmit’s generalizations.14 In any case, though, this does indicate that there aren’t probably an exciting espionage gems hiding in the Alsos records.

Wrapping everything up, my basic conclusion is that if German intelligence had an inkling about the American atomic bomb program, they didn’t develop the idea and they didn’t communicate it to several of their top scientists on the program. Heisenberg seems genuinely foolish on the entire subject. Diebner’s lack of participation makes it hard to gauge his knowledge, but it strikes me as strange (though not impossible) that he would know of such things but Heisenberg would be ignorant of them. Entirely separate is the question of who asked the SS to investigate what the Americans were doing with heavy water — but the queries there demonstrate that whomever is asking knows almost nothing about the Allied program, and may in fact be trying to find out how to improve their own reactor work.

A consistent theme in the Farm Hall transcripts and the Alsos investigation is that the Germans seem to have honestly thought that their work on the “uranium problem” was well beyond what anyone else might have been doing, and that the Allies would be desperate to “buy” their reactor research in the postwar. They apparently were not motivated to check to see whether this arrogance was founded, and part of the depression and desperation one sees them going through after Hiroshima and Nagasaki is a remark on their perception of irrelevance. As Otto Hahn chided them right after they learned of Hiroshima: “If the Americans have a uranium bomb then you’re all second raters.”

Notes
  1. The best copy of the transcripts is Jeremy Bernstein’s heavily annotated version, Hitler’s Uranium Club: The Secret Recordings at Farm Hall, Second Edition (New York: Copernicus Books, 2001). My quotations and citations refer to this specific version. []
  2. Bernstein, 116-117. []
  3. Photochemical processes for enriching uranium were investigated during the Manhattan Project, but not seriously pursued. []
  4. Bernstein, 119. []
  5. Bernstein, 124. []
  6. Bernstein, 139. []
  7. Bernstein, 108. Note that the (?)’s are in the original transcript. []
  8. There is one small bit about talking about thorium with an (Indian) Japanese spy, but it seems unrelated to the bomb question directly, and the spy in question doesn’t seem to have known anything. []
  9. David Kahn writes in Hitler’s Spies: German Military Intelligence in World War II, “[Erich] Gimpel’s [one of the spies] ghostwritten book, Spy for Germany, must be used with the greatest caution, as it differs in a number of critical points from his statement [to the FBI]. The most important are the book’s claims that he was assigned to ferret out atomic secrets, that he succeeded to some extent, and that he radioed a message to Germany. None of these are supported by his statement or by Colepaugh’s [a collaborator] or by postwar interrogations of his spymasters, and the atomic claim is specifically contradicted by a statement of Schellenberg’s [a top Nazi spy].” There just doesn’t seem to be any hard evidence behind the assertion that Elster had something to do with the Manhattan Project. Gimpel’s books provide zero believable details about the matter — he reports that he was just supposed to figure out what was going on (no list of targets, names, theories, etc. []
  10. J. Edgar Hoover to Harry Hopkins (9 February 1945), in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 62: “Security (Manhattan Project),” Roll 4, Target 8. []
  11. See Samuel Goudsmit, Alsos (Tomash, 1983 [1946]), 183-185. []
  12. At one point in the Farm Hall transcripts, it is noted that “Hahn remarked on the fact that there had been no publication of work on uranium fission in British or American scientific journals since January 1940, but he thought there had been one published in Russia on the spontaneous fission of uranium with deuterons.” So, at least retrospectively, Hahn realizes that there was this silence, with the exception of Flerov (probably the Russian he is thinking about). []
  13. Goudsmit describes a conversation between Paul Rosbaud and Walther Gerlach in February 1945 in which Rosbaud asks Gerlach, “Have you considered that the American, British, or Russian scientists know as much or perhaps more about it than you do?” If this actually occurred, one wonders if Gerlach didn’t follow up on the issue, ergo the spy query. But this is just supposition. On the conversation, see Goudsmit, Alsos, 185. In any case, the whole conversation, if true, is further evidence of Gerlach’s ignorance at that point — he was still under the delusion that the Allies would have something to gain from the German work on heavy water. []
  14. Samuel Goudsmit to C.P. Nichols, “Scientific Intelligence” (26 November 1945), Goudsmit papers. []