Visions

Oppenheimer and the Gita

by Alex Wellerstein, published May 23rd, 2014

What was going through J. Robert Oppenheimer’s head when he saw the great fireball of the Trinity test looming above him? According to his brother, Frank, he only said, “it worked.” But most people know a more poetic account, one in which Oppenheimer says (or at least thinks) the following famous lines:

I remembered the line from the Hindu scripture, the Bhagavad-Gita; Vishnu is trying to persuade the Prince that he should do his duty and, to impress him, takes on his multi-armed form and says, “Now I am become Death, the destroyer of worlds.” I suppose we all thought that, one way or another.

This particular version, with a haggard Oppenheimer, was originally filmed for NBC’s 1965 The Decision to Drop the Bomb. I first saw it in Jon Else’s The Day After Trinity (1980), and thanks to YouTube it is now available pretty much anywhere at any time. There are other versions of the quote around — “shatterer of worlds” is a common variant — though it did not begin to circulate as part of Los Alamos lore until the late 1940s and especially the 1950s.

It’s a chilling delivery and an evocative quote. The problem is that most of the time when it is invoked, it is done purely for its evocativeness and without any understanding as to what it actually supposed to mean. That’s what I want to talk about: what was Oppenheimer trying to say, presuming he was not just trying to be gnomic? What was he actually alluding to in the Gita?

An Indian greeting card for Diwali from 1998, celebrating India's nuclear tests. Source.

An Indian greeting card for Diwali from 1998, celebrating India’s nuclear tests. Source.

I should say first that I’m no scholar of Hindu theology. Fortunately, many years back, James A. Hijiya of the University of Massachusetts Dartmouth wrote a wonderful article on “The Gita of J. Robert Oppenheimer” that covers all of this topic as well as one might ever want it to be covered.1 Everything I know about the Gita comes from Hijiya’s article — so read it if you want much more discussion of this than I have here. I am particularly fond of Hijiya’s opening line, that Oppenheimer’s paraphrase of the Gita is “one of the most-cited and least-interpreted quotations” of the atomic age.

Oppenheimer was not a Hindu. He was not much of anything, religiously — he was born into a fairly secular Jewish family, embraced the Ethical Culture of Felix Adler, and saw philosophy as more of a boon to his soul than any particular creed. He enjoyed the ideas of the Gita, but he was not religious about it. Hijiya thinks, however, that much can be understood about Oppenheimer’s life through the lens of the Gita as a philosophical and moral code, something necessary in part because Oppenheimer rarely discussed his own internal motivations and feelings about making the bomb. It helps explain, Hijiya argues, that a man who could utter so many public statements about the “sin” and “terror” and “inhumanity” of Hiroshima and Nagasaki could also have been the one who pushed for their use against Japan and who never, ever said that he actually regretted having built the bomb or recommending its use. It helps resolve one of the crucial contradictions, in other words, at the heart of the story of J. Robert Oppenheimer.

J. Robert Oppenheimer, from the Emilio Segrè Visual Archives.

J. Robert Oppenheimer, from the Emilio Segrè Visual Archives.

It’s not clear when Oppenheimer was first exposed to the Gita. I have seen accounts, in oral histories, that suggested that he was spouting Gita lines even while he was a young graduate student studying in Europe. What is definitely known is that he didn’t start studying Sanskrit seriously until 1933, when he started studying with the renown Sanskrit scholar Arthur W. Ryder while he was a professor at Berkeley. In letters, he wrote gushingly about the book to his brother, and much later he quoted from it at the service held at Los Alamos in April 1945 upon the death of President Roosevelt.

The story of the Gita is that of Arjuna, a human prince who has been summoned to a war between princely cousins. Arjuna doesn’t want to fight — not because he lacks courage, or skill, but because it is a war of succession, so his enemies are his own cousins, his friends, his teachers. Arjuna does not want to kill them. He confides in his charioteer, who turns out to be the god Krishna2 in a human form. The text of the Gita is mostly Krishna telling Arjuna why Arjuna must go to war, even if Arjuna does not want to do it.

Krishna’s argument hinges on three points: 1. Arjuna is a soldier, and so it is his job — his duty — to wage war; 2. It is Krishna’s job, not Arjuna’s, to determine Arjuna’s fate; 3. Arjuna must ultimately have faith in Krishna if he is going to preserve his soul.

Arjuna eventually starts to become convinced. He asks Krishna if he will show him his godlike, multi-armed form. Krishna obliges, showing Arjuna an incredible sight:

Krishna revealing himself to Arjuna. Source.

Krishna revealing himself to Arjuna. Source.

A thousand simultaneous suns
     Arising in the sky
Might equal that great radiance,
     With that great glory vie.

Arjuna is awestruck and spellbound:

Amazement entered him; his hair
     Rose up; he bowed his head;
He humbly lifted folded hands,
     And worshipped God. . . .

And then, in his most amazing and terrible form, Krishna tells Arjuna what he, Krishna, is there to do:

Death am I, and my present task
     Destruction.

Arjuna, suitably impressed and humbled, then agrees to join in the battle.

The above quotes are from Ryder’s translation of the Gita. You can see that Oppenheimer’s is not especially different from that, even if it is somewhat changed. Personally I find Ryder’s version of the last part more impressive — it is more poetic, more stark. Ryder’s translation, Hijiya explains, is a somewhat idiosyncratic but defensible one. What Ryder (and Oppenheimer) translate as “Death,” others have translated as “Time,” but Hijiya says that Ryder is not alone for calling attention to the fact that in this context the expanse of time was meant to be a deadly one.

If you would like to see the famous “death” verse in the original, it is chapter 11, verse 32 of the Gita, and looks like this:

Gita verse 11:32

This website (from which I got the above) translates it as:

Lord Krsna said: I am terrible time the destroyer of all beings in all worlds, engaged to destroy all beings in this world; of those heroic soldiers presently situated in the opposing army, even without you none will be spared.

While I find Ryder’s more poignant, the longer translation makes it extremely clear what Krishna has in mind. All will perish, eventually. In war, many will perish whether you participate or not. For Oppenheimer and the bomb, this may have seemed especially true. The cities of Hiroshima and Nagasaki (and others on the target list) were on it not because they were necessarily the most important, but because they had so far been spared from firebombing. They were being actively preserved as atomic bomb targets. Had the bomb not been used or made, they probably would have been firebombed anyway. Even if the physicists had refused to make nuclear weapons, the death toll of World War II would hardly have been altered.

Trinity long exposure

“A thousand simultaneous suns”: a long-exposure shot of the Trinity test.

So let’s step back and ask who Oppenheimer is meant to be in this situation. Oppenheimer is not Krishna/Vishnu, not the terrible god, not the “destroyer of worlds” — he is Arjuna, the human prince! He is the one who didn’t really want to kill his brothers, his fellow people. But he has been enjoined to battle by something bigger than himself — physics, fission, the atomic bomb, World War II, what have you — and only at the moment when it truly reveals its nature, the Trinity test, does he fully see why he, a man who hates war, is compelled to battle. It is the bomb that is here for destruction. Oppenheimer is merely the man who is witnessing it. 

Hijiya argues that Oppenheimer’s sense of Gita-inspired “duty” pervades his life and his government service. I’m not sure I am 100% convinced of that. It seems like a heavyweight philosophical solution to the relatively lightweight problem of a life of inconsistency. But it’s an interesting idea. It is perhaps a useful way to think about why Oppenheimer got involved with so many projects that he, at times, seemed ambivalent about. Though ambivalence seemed readily available in those days — nobody seems to be searching for deep scriptural/philosophical justifications for Kenneth Bainbridge’s less eloquent, but equally ambivalent post-Trinity quote: “Now we’re all sons-of-bitches.”

A rare color photograph of Oppenheimer from October 1945, with General Groves and University of California President Robert Sproul, at the Army-Navy "E" Award ceremony. Source.

A rare color photograph of Oppenheimer from October 1945, with General Groves and University of California President Robert Sproul, at the Army-Navy “E” Award ceremony. Source.

One last issue that I find nagging me. We have no recording of Oppenheimer saying this except the 1965 one above. By this time, Oppenheimer is old, stripped of his security clearance, and dying of throat cancer. It is easy to see the clip as especially chilling in this light, given that is being spoken by a fading man. How would it sound, though, if it was coming from a younger, more chipper Oppenheimer, the one we see in photographs from the immediate postwar period? Would it be able to preserve its gravity?

Either way, I think the actual context of the quote within the Gita is far deeper, far more interesting, than the popular understanding of it. It isn’t a case of the “father” of the bomb declaring himself “death, the destroyer of worlds” in a fit of grandiosity or hubris. Rather, it is him being awed by what is being displayed in front of him, confronted with the spectacle of death itself unveiled in front of him, in the world’s most impressive memento mori, and realizing how little and inconsequential he is as a result. Compelled by something cosmic and terrifying, Oppenheimer then reconciles himself to his duty as a prince of physics, and that duty is war.

  1. James A. Hijiya, “The Gita of J. Robert Oppenheimer,” Proceedings of the American Philosophical Society 144, no. 2 (June 2000), 123-167. [↩]
  2. Oppenheimer, in his 1965 interview, identifies the god as Vishnu, perhaps in error. Krishna is an avatar of Vishnu, however, so maybe it is technically correct along some line of thinking. [↩]

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News and Notes

Changing venues: from DC to NYC

by Alex Wellerstein, published May 16th, 2014

I haven’t posted as much as I’ve wanted to this month. The main culprits have been teaching, grading, writing, and a week of stomach flu. All of which are pretty OK by me except the last one, which was the exact opposite of pleasant. But I’m better now. But one of the other things that has been brewing has been me finalizing and preparing for a new job. As many of you know, for the past three years I’ve been the Associate Historian at the Center for History of Physics at the American Institute of Physics, in College Park, Maryland, which is just outside of Washington, DC.

Where I've been for the past three years: the American Institute of Physics.

Where I’ve been for the past three years: the American Institute of Physics, in College Park, MD. 

The position was a postdoctoral fellowship. It gave me the flexibility to start the blog, to make the NUKEMAP, to do a lot of talking with people in DC, to write whatever I wanted, and to teach at Georgetown in the Spring 2014 semester. It has been a wonderful place for me to explore what kind of work I wanted to produce, and one couldn’t ask for a better incubator for someone who was recently out of grad school and was still figuring out exactly what I wanted to be doing.

But it was always a fixed-term (3 year) position, destined to end in the late summer of 2014. So I’ve spent some time over the past eight months or so thinking about what I wanted to do next, and see who would take me. It was important to me that wherever I landed that I be allowed to continue the kind of scholarship that I’ve been doing for the last few years, including the digital projects. Aside from the professional benefits it has conferred upon me from the increased exposure (I’m plugged into communities now that never knew I existed before), it has helped me develop my writing (my “voice”) and helped me to think about ways to use the unique benefits of the web (e.g. interactive data visualization/manipulation that is massively scalable and distributable) to further public understanding of issues I care about.

So I’m excited to announce that I have accepted, a tenure track position as an Assistant Professor of Science and Technology Studies at the Stevens Institute of Technology in Hoboken, New Jersey. It’s a small engineering school with a lively humanities division, and they’ve made it clear that they like what I do as I’ve been doing it and want me to do even more. This is a huge draw for me, because I knew that my Internet-related activities, however hard this may be for any of my readers to fathom, would not be a great fit with many more traditional academic departments. And hey, they want me to teach a class on the past, present, and future of nuclear technology my first semester there — what’d I say about a good fit?

Also, the location is pretty impressive. This is my obligatory, “where is this place” photograph, taken from one of their promotional brochures, of course:

Stevens Institute of Technology

Where I’m moving to: the Stevens Institute of Technology, in Hoboken, NJ, just outside of NYC.

Stevens are the buildings above and to the right of the main athletic field above. The body of water is the Hudson River; the skyscrapers on the other side are midtown Manhattan. The big one is the Empire State Building. So basically I’m going to be a short ferry across (or train/bus ride under) the river from New York City. So you could call this my Manhattan Project, if you wanted to be punny about it. My wife has also managed to find a good job in the area, too, which is one of the things I was waiting on before announcing this. She is going to be teaching at one of the best prep schools in the country out there, which I think is going to be a great fit for her. We are feeling exceptionally fortunate.

As with all job changes and moves, there is a bittersweet aspect to this. I’ve really enjoyed living in Washington for the last three years. I thought it was a fun, exciting town, and there’s probably no better place in the world for people who study secrecy and nukes. So many interesting people, so many interesting talks, so many interesting events. Fortunately the train ride from New York to DC is very pleasant, so I hope my DC friends and acquaintances will consider me not too far away. Or, as I like to put it, you’ve got another friend in the NYC area.

I’ll be moving there over the summer, sometime in late July or early August. Don’t worry, the blog is going to keep chugging along — during and after the move. Now that teaching is done I want to squeeze in a few more DC archive research trips while I still live a few blocks from the Library of Congress, and I have a few blog posts I’ve been working on for awhile. The visualization/app work may even be accelerated in the years to come, because at Stevens they want me to try and teach students how to do similar things, and that always leads to more little inspirations. Keep an eye on this space. I thank you, and AIP in particular, for the support that made this possible.

Posted in News and Notes | 19 Comments »

Meditations

Szilard’s chain reaction: visionary or crank?

by Alex Wellerstein, published 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 way. Which 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.

  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. [↩]

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Redactions

Accidents and the bomb

by Alex Wellerstein, published April 18th, 2014

When I first heard that Eric Schlosser, the investigative journalist was writing a book on nuclear weapons accidents, I have to admit that I was pretty suspicious. I really enjoyed Fast Food Nation when it came out a decade ago. It was one of those books that never quite leaves you. The fact that the smell of McDonald’s French fries was deliberately engineered by food chemists to be maximally appealing, something I learned from Schlosser’s book, comes to mind whenever I smell any French fries. But nuclear weapons are not French fries. When writing about them, it is extremely easy to fall into either an exaggerated alarmism or a naïve acceptance of reassuring official accounts. In my own work, I’m always trying to sort out the truth of the matter, which is usually somewhere in between these two extremes.

Schlosser - Command and Control book

This is especially the case when talking about nuclear weapons accidents — the many times during the Cold War when nuclear weapons were subjected to potentially dangerous circumstances, such as being set on fire, being accidentally dropped from a bomber, crashing with a bomber, having the missile they were attached to explode, and so on. The alarmist accounts generally inflate the danger of the accidents achieving a nuclear yield; the official accounts usually dismiss such danger entirely. There are also often contradictory official accounts — sometimes even the people with clearances can’t agree on whether the weapons in question were “armed” (that is, had intact fissile pits in them), whether the chance of detonation was low or high, and so on. I’ve always been pretty wary about the topic myself for this reason. Sorting out the truth seemed like it would require a lot of work that I wasn’t interested in doing.

Well, I’m happy to report that in his new book, Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety, Schlosser has done that work. I reviewed the book recently for Physics Today. You can read my PT review here, but the long and short of it is that I was really, really impressed with the book. And I’m not easily impressed by most works of nuclear weapons history, popular or academic. I’m not surprised it was a finalist for the Pulitzer Prize, either.

Titan II silo complex. There's a lot going on in one of these. This, and all of the other Titan II images in this post, are from Chuck Penson's wonderful, beautiful Titan II Handbook.

Titan II silo complex. There’s a lot going on in one of these. This, and all of the other Titan II images in this post, are from Chuck Penson’s wonderful, beautiful Titan II Handbook.

What I ask out of a new book is that it teach me something new — either novel facts or novel spins on things I already knew about. Schlosser’s book does both. He clearly did his homework when it came to doing the work, and it’s not really surprising it took him about a dissertation’s worth of time to write it. It’s not just a document dump of FOIA’d material, though. He really shines when contextualizing his new information, writing a very rich, synthetic history of nuclear weapons in the Cold War. So the new and the old are woven together in a really spectacular, unusually compelling fashion.

The book has two main threads. One is a very specific, moment-by-moment account of one accident. This is the so-called Damascus Accident, which is when a Titan II missile in Damascus, Arkansas, exploded in its silo in 1980, resulting in one fatality. It’s not one of the “standard” accidents one hears about, like the 1961 Goldsboro bomb, the 1958 Tybee bomb, the 1968 Thule crash, or the 1966 Palomares accident. But Schlosser’s journalist chops here really came through, as he tracked down a huge number of the people involved in the accident and used their memories, along with documentary records, to reconstruct exactly how one dropped spanner — itself just an apparently innocuous, everyday sort of mistake — could lead to such explosive outcomes.

The other thread is a more historical one, looking at the history of nuclear weapons and particular how the problem of command and control runs through it from the beginning. “Command and control” is one of those areas whose vastness I didn’t really appreciate until reading this book. Nominally it is just about making sure that you can use the weapons when you want to, but that also includes making sure that nobody is going to use the weapons when you don’t want them to, and that the weapons themselves aren’t going to do anything terrible accidentally. And this makes it mind-bogglingly complex. It gets into details about communication systems, weapons designs, delivery system designs, nuclear strategy, screening procedures, security procedures, accident avoidance, and so much more.

How do you service a Titan II? Very carefully. This is a RFHCO suit, required for being around the toxic fuel and oxidizer. Not the most comfortable of outfits. From Penson's Titan II Handbook.

How do you service a Titan II? Very carefully. This is a RFHCO suit, required for being around the toxic fuel and oxidizer. Not the most comfortable of outfits. From Penson’s Titan II Handbook.

Schlosser weaves this all together wonderfully. I found very few statements, technical or otherwise, that struck me as genuine outright errors.1 Of course, there are places where there can be differences of interpretation, but there always are. This is pretty good for any book of this length and scope — there are many academic books that I’ve read that had more technical errors than this one.

What I found really wonderful, though, is that Schlosser also managed to give a compelling explanation for the contradictory official accident accounts that I mentioned before. It’s so simple that I don’t know why it never occurred to me before: the people concerned with nuclear weapon safety were not the same people who were in charge of the weapons. That is, the engineers at Sandia who were charged with nuclear safety and surety were institutionally quite remote from the Air Force people who handled the weapons. The Air Force brass believed the weapons were safe and that to suggest otherwise was just civilian hogwash. The engineers who got into the guts of the weapons knew that it was a more complicated story. And they didn’t communicate well — sometimes by design. After awhile the Air Force stopped telling the Sandia engineers about all of the accidents, and so misinformation became rampant even within the classified system.

The fate of the world in a few punched holes. Penson: "Targeting information was stored on Mylar-backed punched paper tape. Though primitive by today's standards, punched paper tape will retain data decades longer than magnetic tapes or CDs. This tape is somewhat worse for wear from 20 years of museum use, but probably would still work."

The fate of the world in a few punched holes. Penson: “Targeting information was stored on Mylar-backed punched paper tape. Though primitive by today’s standards, punched paper tape will retain data decades longer than magnetic tapes or CDs. This tape is somewhat worse for wear from 20 years of museum use, but probably would still work.”

We usually talk about nuclear weapons safety as a question of whether they are “one-point safe.” That is, will the weapon have a chance of a nuclear yield if one point on the chemical explosives surrounding the fission pit detonated inadvertently? Most of the time the answer is no, of course not. Implosion requires a very high degree of detonation symmetry — that’s why it’s hard to make work. So a one-point detonation of the explosive lenses will produce a fizzle, spreading plutonium or uranium like a “dirty bomb” but not producing a supercritical chain reaction.

But some of the time, answer is, “well, maybe.” We usually think of implosions as complex affairs but some weapons only require two-point implosion to begin with. So now you’re no longer talking about the possibility that one out of 36 explosive lenses will go off; you’re talking about one out of two. This isn’t to say that such weapons aren’t one-point safe, just to point out that weapons design isn’t limited to the sorts of things present in the first implosion weapons.

But even this doesn’t really get at the real problem here. “One-point safe” is indeed an important part of the safety question, but not the only one. Consider, for example, what would happen if the firing signal was only a simple amount of DC electrical current. Now imagine that during a fire, the firing circuit board soldering melts and a short-circuit is formed between the batteries and the firing switch. Now the bomb is actually trying to truly set itself off as if it had been deliberately dropped — and full implosion, with nuclear yield, is totally possible.

The injector plate of a Titan II. I thought the somewhat abstract pattern of holes and corrosion on the recovered plate made for a beautiful image. The diagram at left shows you what you are looking at — this is where fuel and oxidizer would come together, propelling the missile.

The injector plate of a Titan II. I thought the somewhat abstract pattern of holes and corrosion on the recovered plate made for a beautiful image. The diagram at left shows you what you are looking at — this is where fuel and oxidizer would come together, propelling the missile.

How likely is this kind of electrically-activated nuke scenario? What the Sandia engineers discovered was that in some weapons it was really not implausible at all. Under the “abnormal environment” of a weapons accident (such as a crashing or burning B-52), all sorts of crazy things could happen with electronic circuits. And unless they were really carefully designed for the possibility of this kind of accident, they could arm themselves and fire themselves. Which is the kind of thing you’d expect an engineer who is deeply connected with the electrical technology of the bomb to conclude.

And of course, as Schlosser (and his engineer sources) point out — this kind of thing is only one small detail in the broad, broad question of nuclear safety. These systems are big, complex, and non-linear. And so much hinges on them working correctly.

The sociologist of science Donald MacKenzie has proposed (in a slightly different context — nuclear weapons accuracy, not safety) that a “certainty trough” exists with regards to complex questions of technological uncertainty. He draws it somewhat like this:2

MacKenzie's Certainty Trough

So this divides people into three groups. On the left are the people who actually build the technology and the knowledge. These people have reasonably high levels of uncertainty about the technology in question — they know the nuts and bolts of how it works and how it could go wrong. (I’ve added “confidence” as a label because I find it more straightforward than “uncertainty” at times.) They also know what kinds of failure situations are not likely as well. In the middle, you have people who are completely committed to the technology in question. These people aren’t completely divorced from solid knowledge about it, but they are just consumers of knowledge. They look at the final data, but they don’t really know how the data was made (and all of the uncertainty that gets screened out to make the final version of the data). They have very low uncertainty, and so very high confidence in the technology. At far right you have the people who are either total outsiders, or people who are totally committed to another approach. These have the highest levels of uncertainty and the lowest levels of confidence.

So if we were mapping Schlosser’s actors onto these categories, we’d have the Sandia engineers and other weapons scientists on the far left. They know what can go wrong, they know the limits of their knowledge. They also know which accident situations are outlandish. In the middle we have the military brass and even the military handlers of the weapons. They are committed to the weapons. They have data saying the weapons are safe — but they don’t know how the data was made, or how it was filtered. They think the weapons are totally safe and that anyone who suggests otherwise is just ignorant or foolish. And lastly, at far right, we have total outsiders (the activists, perhaps, or sometimes even politicians), or people who really are looking to amplify the uncertainty for their own purposes.

Titan II Launch Control Center, with the facilities console at center. From Penson.

Titan II Launch Control Center, with the facilities console at center. From Penson.

The disconnect between the far left group and the middle group is the one that disturbs me the most in Schlosser’s account. It also reflects what I’ve seen in online discussions of weapons accidents. People with a little bit of knowledge — e.g. they know about one-point safety, or they once handled nukes in the military — have very high confidence in the safety issues. But they don’t know enough to realize that under the hood, things are more complicated and have been, in the past at least, much more dangerous. Not, perhaps, as dangerous as some of the more alarmist, outsider, activist accounts have stressed. But dangerous enough to seriously concern people whose jobs it is to design the weapons — people who know about the nuts and bolts of them.

Anyway. Schlosser’s book is a great read, as well. Which it needs to be, because it is long. But it’s also segregable. Don’t care much of the details of the Damascus accident? You can skip those sections and still get a lot out of the book (even though the Damascus accident is really a perfect account of all of the little things that can go wrong with complex, non-linear systems). But part of that length is a copious amount of endnotes, which I applaud him and his publisher for including. For a book like this, you can’t skimp on the documentation, and Schlosser doesn’t. The only thing he did skimp on was illustration, which I — as a pretty visual guy — thought was too bad. So much of the Damascus story takes place inside of a Titan II silo, and while the inner flap of the cover did have a simplified illustration of one, I still felt like I didn’t really know what was happening where at times. (I wonder if this was a trade-off with the publisher in having so many notes and pages.)

Chuck Penson's Titan II Handbook, and one of its several amazing fold-out diagrams. Adorable pupper (Lyndon) for scale.

Chuck Penson’s Titan II Handbook, and one of its several amazing fold-out diagrams. Adorable pupper (Lyndon) included for scale.

Fortunately, there is a solution for this. If it were up to me, every copy of Schlosser’s book would be accompanied by a copy of Chuck Penson’s Titan II Handbook: A civilian’s guide to the most powerful ICBM America ever built. Penson’s book is a richly illustrated history of this particular missile, and contains lots of detailed photographs and accounts of daily life on a Titan II base (such as those seen above) It’s utterly fascinating and it gives so much visual life to what Schlosser describes. It also includes giant fold-out diagrams of the missiles themselves — the printing quality is really impressive all around. It includes fascinating technical details as well. For example, in the early days of the Titan II silos they had large motor-generators that constantly ran in case they needed to convert DC power into AC in the event of a failure of commercial power. Penson then notes that:

The motor-generator ran with a loud, monotonous high-pitched whine… noise in the [Launch Control Center] turned into a serious issue. Crew members complained of temporary hearing loss due not only the incessant buzz of the motor-generator, but also to the constant drone of the air conditions, fans and blowers in equipment. Eventually the Air Force covered the tile floor with carpeting, and acoustic batting was hung in the in the area of the stairway leading up to level 1 and down to level 3. … These changes made a tremendous improvement, but one that came too late for many of the crew, a significant number of whom now need hearing aids.

This kind of detail fits in perfectly with Schlosser’s approach to the facility, which itself seems strongly influenced by the sociologist Charles Perrow’s notion of “Normal Accidents.” That the devices in the facility would affect the hearing of the crew was certainly not something that anybody thought of ahead of time; it’s one of those little details that gets lost in the overall planning, but (at least for those who suffered the hearing loss) had real consequences. Ultimately this is the thesis of Schlosser’s book: that the infrastructure of nuclear command and control is much larger, much more complex, much more problematic than most people realize, and is one of those high-complexity, high-risk systems that human beings are notoriously pretty bad at managing.

If you’re the kind of person who geeks out on nuke history, both Schlosser’s and Penson’s books are must-reads, must-buys.

  1. The two biggest mistakes I noted, which I’ve told Schlosser about and may be fixed in the paperback, are that he misstates the size of the neutron initiator in the Fat Man bomb — he confuses the diameter for the radius — and he got the story of Szilard’s 1933 chain reaction work wrong, which lots of people do. Szilard’s patent is such a common source of misunderstanding even amongst scholars that I will be writing a blog post about it soon. Neither of these are terribly important to his argument or narrative. [↩]
  2. Adapted from Donald MacKenzie, Inventing Accuracy: A Historical Sociology of Nuclear Missile Guidance (Cambridge, Mass.: MIT Press, 1990), figure 7.2. [↩]

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Visions

The plutonium box

by Alex Wellerstein, published March 28th, 2014

I’ve found myself in a work crunch (somehow I’ve obligated myself to give three lectures in the next week and a half, on top of my current teaching schedule!), but I’m working on some interesting things in the near term. I have a review of Eric Schlosser’s Command and Control coming out in Physics Today pretty soon, and I’ll post some more thoughts on his book once that is available. And I have something exciting coming up for the 60th anniversary of Oppenheimer’s security hearing.

In the meantime, I wanted to share the results of one little investigation. I’ve posted a few times now (Posing with the plutonium, Little boxes of doom, The Third Core’s Revenge) on the magnesium boxes that were used to transport the plutonium cores used for the Trinity test and the Fat Man bomb:

The magnesium cases for the world's first three plutonium cores. Left: Herb Lehr at Trinity base camp with the Gadget core. Center: Luis Alvarez at Tinian with the Fat Man core. Right: The third core's case at Los Alamos, 1946.

The magnesium cases for the world’s first three plutonium cores. Left: Herb Lehr at Trinity base camp with the Gadget core. Center: Luis Alvarez at Tinian with the Fat Man core. Right: The third core’s case at Los Alamos, 1946.

Just to recap, they were a design invented by Philip Morrison (the Powers of Ten guy, among other things), made out of magnesium with rubber bumpers made of test tube stoppers. They could hold the plutonium core pieces (two in the case of the Trinity Gadget, three in the case of Fat Man), as well as neutron initiators. Magnesium was used because it was light, dissipated heat, and did not reflect neutrons (and so wouldn’t create criticality issues). All of this information is taken from John Coster-Mullen’s Atom Bombs, an essential book if you care about these kinds of details.

But all of the photographs of the box I had seen, like those above, were in black and white. Not a big deal, right? But I find the relative lack of color photography from the 1940s one of those things that makes it hard to relate to the past. When all of Oppenheimer’s contemporaries talked about his icy blue eyes, it makes you want to see them as they saw them, doesn’t it? Maybe it’s just me.

The only place where I almost saw a color photo of the box is in a photo that the late Harold Agnew had taken of himself on Tinian. It’s one of a large series of posing-with-plutonium photos that were taken on the island of Tinian sometime before the Nagasaki raid. Only this one is in color! Except… well, I’ll let the photo speak for itself:

Harold Agnew with plutonium core redacted

Yeah. Not super helpful. This was scanned from Rachel Fermi and Esther Samra’s wonderful Picturing the Bomb book. They asked Agnew what had happened, and he told them that:

I was in Chicago after the war in 1946. The FBI came and said they believed I had some secret pictures. They went through my pictures and found nothing. Then like a fool I said, “Maybe this one is secret.” They wanted to know what that thing was. I told them and they said that it must be secret and wanted the picture. I wanted the picture so they agreed if I scratched out the “thing” I could keep the slide.

Thwarted by nuclear secrecy, once again! You can try to look extra close at the scratches and maybe just make out the color of the “thing” but it’s a tough thing to manage.

Ah, but there is a resolution to this question. Scott Carson, a retired engineer who posts interesting nuclear things onto his Twitter account, recently posted another  photo of the box — in color and unredacted! His source was a Los Alamos newsletter from a few years back. It is of Luis Alvarez, another member of the Tinian team, in the same exact pose and location as the redacted Agnew photograph… but this time, un-redacted! And the color of the box was…

Luis Alvarez with the Fat Man core, Tinian, 1945.

…yellow? Not what I was expecting.

Why yellow? My guess: it might be the same yellow paint used on the Fat Man bomb. Fat Man was painted “a mustard yellow rust-preventing zinc-chromate primer” (to quote from Coster-Mullen’s book) that made them easier to spot while doing drop tests of the casings.

The box for the Trinity core doesn’t look painted yellow to me — it looks more like raw magnesium. Maybe they decided that the tropical atmosphere of Tinian, with its high humidity, required painting the box to keep it from oxidizing. Maybe they just thought a little color would spruce up the place a little bit. I don’t know.

Does it matter? In some sense this is pure trivia. If the box was blue, green, or dull metallic, history wouldn’t be changed much at all. But I find these little excursions a nice place to meditate on the fact that the past is a hard thing to know intimately. We can’t see events exactly as they were seen by those who lived them. Literally and figuratively. The difficulty of finding out even what color something was is one trivial indication of this. And the secrecy doesn’t help with that very much.

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