Posts Tagged ‘Counterfactuals’

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FDR and the bomb

Friday, September 30th, 2016

Franklin D. Roosevelt is one of the most enigmatic figures of the early American atomic bomb program. The four-term US president always features briefly in any story of the Manhattan Project: first, for his creation of the Advisory Committee on Uranium, an exploratory research effort in response to a letter urging government action that was sent by Albert Einstein in August 1939; second, for his approval of a broader expansion of that research into a “pilot” program in late 1941, just before the US entry into World War II, which resulted in more intensive investment into uranium enrichment and reactor design; and third, in mid-1942, Roosevelt approved bringing in the US Army Corps of Engineers to manage a full-scale bomb-production project. This latter action is often subsumed by the attention given the first two, but it is the production program decision that actually resulted in the US getting an atomic bomb by 1945, and is the decision that makes the United States unique among powers in the Second World War, as while several powers had research programs, only the US turned it into a production program. It was the beginning of the Manhattan Project as we tend to characterize it, the kind of program that produces weapons and not just data.

A little history trick I always tell my students: if you see Truman and FDR in the same photograph, that means Truman doesn't know about the atomic bomb. Photo source: History.com

A little history trick I always tell my students: if you see Truman and FDR in the same photograph, that means Truman doesn’t know about the atomic bomb. Photo source: History.com

So Roosevelt looms large, as he ought to. Without Roosevelt’s actions, there would have been no atomic bomb in World War II. And yet… What did FDR really think about the atomic bomb? Did he see it as a true end-the-war weapon? Did he think it was meant to be used in war (as a first-strike weapon) or did he think of it primarily as a deterrent (i.e., against the Germans)? The question isn’t just an idle one, because Roosevelt’s sudden death, on April 12, 1945, left his successor, Harry Truman, with major decisions to make about the future of the war, and Truman, in part, thought he was acting in accordance with FDR’s wishes on this matter. But, as is well known, FDR never told Truman about the atomic bomb work, and never set out his wishes on this matter — so there was a tremendous amount of assumption involved.

I get asked about FDR’s views on a fairly regular basis, and it’s one of those wonderful questions that seems simple but is really quite complex, and quickly gets you into what I think of as “epistemological territory”: How do we know what someone’s views were, in the past? How do we get inside the head of someone dead? Well, you might say, obviously we can’t completely get inside someone’s head (we can barely get inside the heads of people who are alive and in front of us, and a Freudian might argue that we barely have conscious access to our own motivations and thoughts), but we can look at what evidence there is that was written down that might reveal some of their inner thoughts.

But with FDR, this is very tricky: he didn’t write that much down. He didn’t keep a diary or journal. He didn’t send that many letters. He didn’t record phone calls, conversations, write “memos to self,” or any of the other documenting habits that are common to major political figures. He was notoriously secretive and private. He didn’t explain himself. If Truman was comparatively straightforward in his thinking and action, Roosevelt was a grand schemer, trying to out-wit and out-charm the world (sometimes successfully, sometimes not). He could be downright gnomic. At one point, Vannevar Bush (FDR’s top science advisor) asked Roosevelt whether the Secretary of the Navy ought to be included in discussions on the bomb project. He later recalled that FDR “looked at me with one of his strange smiles and said, ‘No, I guess not, not now.'” End of anecdote, no real indication as to what FDR was thinking, other than a “strange smile” that no doubt concealed much.1

What approval of a nuclear weapons program looked like under Roosevelt: "VB OK FDR." Report by Vannevar Bush of June 16, 1942, asking to expand the fission work into an all-out effort.

What approval of a nuclear weapons program looked like under Roosevelt: “VB OK FDR.” Report by Vannevar Bush of June 16, 1942, asking to expand the fission work into an all-out effort.

As this example indicates, we do sometimes have accounts, including contemporary ones, by people who met with Roosevelt and talked with him. But even these can be quite tricky, because FDR did not, again, generally explain his full thinking. So people like Bush were left with half-versions of the story, knowing what FDR said but not what he thought, and while this is, to be sure, a common-enough human experience, with FDR the gap between thought and expression was exceptionally large.

Separately, there is another, related issue that complicates our understanding: people who met with FDR would often use tales of his agreement as a form of authority. Vannevar Bush did this repeatedly, and this is no doubt a pretty standard mode of operation regarding advisors and presidents. Bush would go to FDR with an idea, convince FDR to sign off on Bush’s idea, and then claim it was FDR’s idea, because while people might feel free to disagree with Bush, they couldn’t really disagree with FDR. One of the most famous examples of this is Bush’s report on postwar American science policy, Science—The Endless Frontier, which is constructed to look like it is a reply to a letter by FDR for guidance, but was entirely engineered by Bush as a means of pushing his own agenda, with FDR being a complicit as opposed to a driving force.2

So what do we know? The number of documents that give insight into FDR’s personal thoughts about the atomic bomb — what it was, what it could be used for, what his plans were — are very slim. Some of this is a function of timing: FDR died right around when they were getting concrete estimates for when the atomic bomb would be ready to use, and had he lived until, say, May 1945, he might have been faced with more direct questions about his plans for it. (The first Target Committee meeting was on April 27, and the Interim Committee was created in early May, just to give an indication of how things rapidly started to come together right after FDR died.) So he wasn’t part of the conversations that directly led to the use of the atomic bombs on Japanese cities.

But there are a few other documents that are useful in assessing FDR’s views. It seems fairly clear that FDR’s approval of the Uranium Committee in 1939 was initially because he was interested in the deterrent quality of the bomb. Alexander Sachs, who had the meeting with Roosevelt, related that FDR had confirmed that the goal was “to see that the Nazis don’t blow us up.”3 Again, this wasn’t yet a bomb-making program, it was just a “see if bombs are worth worrying about” program, but that’s still a little insight: it shows, perhaps, that the initial, explicit attraction was not in making a new wonder-weapon, but deterring against another one.

Roosevelt, Truman, and FDR's previous VP, Henry Wallace. Truman is the only one here who doesn't know about the bomb program. Image source: Truman Library via Wikimedia Commons

Roosevelt, Truman, and FDR’s previous VP, Henry Wallace. Truman is the only one here who doesn’t know about the bomb program. Image source: Truman Library via Wikimedia Commons

Between 1939 and 1941 there are big gaps in anything that would indicate FDR’s views on the bomb. This is not surprising, because this was a period of relative lack of movement in the US fission program, which was not yet a bomb program. FDR was occasionally involved in discussions about the program, but there was no “bomb” yet to worry about one way or the other. In late 1941, FDR approved accelerating and expanding the research, at the urging of Bush, James Conant, Ernest Lawrence, and Arthur Compton, and in mid-1942 he approved of a full bomb production program, as previously noted. None of these documents indicate intent for use, however. The June 1942 report by Vannevar Bush and James Conant, whose approval by Roosevelt is indicated only by a scrawled “VB OK FDR” on its cover letter, indicates that a weapon made with 5-10 kilograms of U-235 or Pu-239 (then just called “Element 94”) would have an explosive power of “several thousand tons of TNT.” It goes into great detail on the types of plants to be constructed and the organization of the research. It predicts a “bomb” would be ready by early 1944. But at no point does it indicate what the point of such a weapon was: as a deterrent, as a first-strike weapon, as a demonstration device, etc. There is only point, towards the end, which suggests that a committee be eventually formed to consider “the military uses of the material,” but even this is primarily concerned with research and development for the plants. This is not to say that Bush, Conant, et al. did not have their views on whether it would be a weapon to use or not — but the report does not indicate any such views, and so FDR’s endorsement of it doesn’t tell us much.4

Bush met with Roosevelt many times during the war, and sometimes would write down, afterwards, what they talked about. Clearly this is FDR-as-filtered-through-Bush, but we’ll take what we can get. In late June 1943, Bush wrote to Conant with an account of a recent meeting he had with FDR on “S-1,” their code for the bomb work. In it, Bush related that FDR was curious about the progress of the work and the schedule for having a bomb. Bush told him things were going well but still tentative, and that the date of a bomb had been pushed back to early January 1945, but that this could shift in either direction. FDR also wanted to know how the Germans were doing. Bush explained that they didn’t really know, that they were trying to find ways to slow down any German work, and that they were still worried about being behind the Germans. (They would eventually come to understand they had surpassed them.) Then there is this really interesting passage which is worth quoting from the original:

He [FDR] then himself discussed what the enemy attitude of mind would be if they felt they had this coming along, and were inclined to remain on the defensive until it could eventuate. We then spoke briefly of the possible use against Japan, or the Japanese fleet, and I brought out, or I tried to, that because at this point I do not think I was really successful in getting the idea across, that our point of view or our emphasis on the program would shift if we had in mind use against Japan as compared with use against Germany.5

After which the conversation then shifted to other matters. Such a tantalizing snippet of discussion, but not as fleshed out as one might want! What did Bush and FDR understand the difference to be between the Japanese versus the Germans? Who initially brought up the possibility of use against the Japanese? What did FDR think about the German “attitude of mind”? This snippet hints at exactly the topics one might care about but doesn’t actually reveal anything about FDR’s views on them! Impressively frustrating!

Most of FDR’s interactions with Bush, Groves, and others during this period concerned diplomatic issues, specifically cooperation with the British (a rather long, drawn-out saga), and even a meeting with Niels Bohr (from which FDR mostly took away a fear that Bohr might alert the Soviets, or others, to the US work). FDR helped, for example, in helping to shut down unionization activities at the Berkeley Radiation Laboratory, and was kept abreast of efforts made to monopolize global uranium ore resources. He was not “checked out” in any respect; he was dramatically more concerned with the ins-and-outs of the fission work than, say, Truman would later be. But again, very little of this left any record about what he thought they were going to do with the bomb.6

Atomic diplomacy: Roosevelt and Churchill at Quebec, in September 1944. Source: NARA via Wikimedia Commons

Atomic diplomacy: Roosevelt and Churchill at Quebec, in September 1944. Source: NARA via Wikimedia Commons

Two of the only documents that reveal any FDR-specific thoughts about the use of the bomb were agreements he made with Winston Churchill. In August 1943, Churchill and Roosevelt met in Quebec, Canada, and hammered out the secret “Quebec Agreement.” It said, among other matters, that the US and UK would pool their efforts at both making the bomb and securing global uranium reserves, that they would never nuke each other, that they would never nuke anyone else without mutual agreement, and they would not reveal the secrets of the bombs without mutual agreement. So this at least provides a framework for using the bomb, but it is a limited one — FDR was willing to deliberately tie the US’s hands with regards to dropping of the atomic bomb to the approval of a foreign power, quite an amazing concession!7

Another meeting between Roosevelt and Churchill, in Hyde Park, New York, produced yet another fascinating agreement. The Hyde Park Aide-Mémoire of September 1944 contained the following clause:

The suggestion that the world should be informed regarding tube alloys, with a view to an international agreement regarding its control and use, is not accepted. The matter should continue to be regarded as of the utmost secrecy; but when a “bomb” is finally available, it might perhaps, after mature consideration, be used against the Japanese, who should be warned that this bombardment will be repeated until they surrender.

Here they were explicitly rejecting the appeal by Niels Bohr (which he was able to make personally to both FDR and Churchill, on separate occasions) to alert the world about the atomic bomb. But it is of interest that they were, at this point, specifically thinking about using the bomb against the Japanese (not Germany), but that they thought it would require “mature consideration” before use, and that they were putting “bomb” in scare-quotes. This is one of the few indications we have of FDR’s awareness and acceptance of the idea that the bomb might be used as a first-strike weapon, and against the Japanese in particular.

Lastly, there is one other significant FDR-specific datapoint, which I have written about at length before. In late December 1944, with Yalta looming, Roosevelt and Groves met in the Oval Office (along with Henry Stimson, the Secretary of War). In Groves’ much later recollection (so we can make of that what we will), Roosevelt asked if the atomic bomb might be ready to use against Germany very soon. Groves explained that for a variety of reasons, the most important one being that their schedule had pushed the bomb back to the summer of 1945, this would not be possible. It is an interesting piece, one that simultaneously reveals Roosevelt’s potential willingness to use the atomic bomb as a first-strike weapon, his willingness to use it against Germany specifically, and the fact that FDR was sufficiently out of the loop on planning discussions to not know that this would both be impossible and very difficult. In other words, it reveals that FDR wasn’t aware that by that point, it was expected that the bomb could only be used against Japan, and that is a rather large thing for him not to know — further evidence, perhaps, that he was not completely abreast of these kinds of discussions. At the meeting, Groves gave FDR a report that predicted a weapon ready for use in early August 1945, and specified that it was time to begin military planning, which Groves annotated as having been “approved” by the Secretary of War and the President. But there doesn’t seem to have been any specifics of targets, or even targeting philosophy, agreed upon at this point.8

What can we make of all this? Frequently I have seen people take the position that Truman himself took: assuming that Roosevelt would have used the bomb in the way that Truman did, because what else might he have been planning? I would only caution that there were more “options” on the table even for Truman than we tend to talk about, which is just another way to say that dropping two atomic bombs in rapid succession on cities is not the only way to use an atomic bomb even militarily. That is, even if one thinks it was inevitable that the bombs would be used in a military fashion (which I think is probably true), it is unclear what position FDR might have taken on the question of specific targets (e.g., the Kyoto question), the question of timing (e.g., before or after the Soviet invasion; how many days between each strike?), and diplomatic matters (e.g., would Roosevelt be more open to modifying the Potsdam Declaration terms than Truman was?). So there is room for considerable variability in the “what if Roosevelt hadn’t died when he did?” question, especially given that Roosevelt, unlike Truman, had been following the bomb work from the start, and was as a result much less reliant on his advisors’ views than Truman was (he frequently bucked Bush, for example, when it came to matters relating to the British).

Would Roosevelt have dropped the bomb on Japan, had he not died? I suspect the answer is yes. One can see, in these brief data points, a mind warming up to the idea of the atomic bomb as not just a deterrent, but a weapon, one that might be deployed as a first-strike attack. In some ways, FDR’s query to Groves about Germany is the most interesting piece: this was a step further than anyone else at the time was really making, since Germany’s defeat seemed inevitable at that point. But, again, the strict answer is, of course, that we can’t really know for sure. Perhaps if FDR had confided his inner thoughts on the bomb to more people, perhaps if he had written them down, perhaps if he had been more involved in the early targeting questions, then we would be able to say something with more confidence. Unless some new source emerges, I suspect Roosevelt’s thoughts on the bomb will always have something of an enigma to them. It is not too far-fetched to suggest that this may have always been his intention.

Notes
  1. Vannevar Bush, Pieces of the action (New York: Morrow, 1970), 134. []
  2. See Daniel J. Kevles, “The National Science Foundation and the Debate over Postwar Research Policy, 1942-1945: A Political Interpretation of Science–The Endless Frontier,” Isis 68, no. 1 (1977), 4-26. Another example of this behavior, from my own research, is when Bush wanted to seize patent rights relating to atomic research during the war — this was an idea cooked up by Bush, approved by FDR, and then presented as an idea of FDR’s, to give it more political, legal, and moral heft. See Alex Wellerstein, “Patenting the Bomb: Nuclear Weapons, Intellectual Property, and Technological Control,” Isis 99, no. 1 (2008), 57-87, esp. 65-66. []
  3. Quoted in Richard Rhodes, The Making of the Atomic Bomb (Simon and Schuster, 1986), on 314. []
  4. Vannevar Bush and James Conant, “Atomic Fission Bombs,” (17 June 1942), with attached cover letter initialed by Roosevelt, copy in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 58: “Vannevar Bush Report – March 1942,” Roll 4, Target 4. []
  5. Vannevar Bush to James Conant, “Memorandum of Conference with the President,” (24 June 1943), copy in Bush-Conant File Relating the Development of the Atomic Bomb, 1940-1945, Records of the Office of Scientific Research and Development, RG 227, microfilm publication M1392, National Archives and Records Administration, Washington, D.C., n.d. (ca. 1990), Roll 2, Target 5, Folder 10, “S-1 British Relations Prior to the Interim Committee [Fldr.] No. 2 [1943, some 1944, 1945].” []
  6. For a very nice discussion of Roosevelt’s wartime “atomic diplomacy,” see Campbell Craig and Sergey Radchenko, The atomic bomb and the origins of the Cold War (Yale University Press, 2008), chapter 1, “Franklin Delano Roosevelt and Atomic Wartime Diplomacy,” 1-33. On the UK-US atomic alliances, see Barton Bernstein, “The uneasy alliance: Roosevelt, Churchill, and the atomic bomb, 1940-1945,” Western Political Quarterly 29, no. 2 (1976), 202-230 []
  7. And just to follow up on that: the US did, in the summer of 1945, request formal UK approval for the dropping of the atomic bomb, and for the release of the Smyth Report and other publicity. The UK readily gave assent to using the weapon against the Japanese, but they did question the wisdom of releasing the Smyth Report. They eventually consented to that as well, after stating their reservations. []
  8. Just as an aside: the meeting, by Stimson’s diary account, was only 15 minutes long, and most of it pertained to questions of diplomacy (specifically potential British violations of the Quebec Agreement with respect to French patent arrangements). Stimson’s diary entry mentions nothing about targeting question, German, Japanese, or otherwise. So either the discussion of Germany and Japan did not make much impression on him, or he did not think it prudent to write it down. See Henry Stimson diary entry for December 30, 1944, Yale University. Groves own contemporary record of the meeting also neglects to mention anything relating to targets, and instead is entirely focused on diplomatic questions. Leslie Groves, Memorandum on Meeting with President (30 December 1944), Correspondence (“Top Secret”) of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 3, Target 7, Folder 24, “Memorandums to (Gen.) L. R. Groves Covering Two Meetings with the President (Dec. 30, 1944, and Apr. 25, 1945).” []
Meditations

Tokyo vs. Hiroshima

Monday, September 22nd, 2014

How many people would have died if an atomic bomb had been dropped on Tokyo in early 1945, instead of firebombs? Before you accuse me of excessive obsession with morbidity (as one anonymous e-mailer recently did), let me explain to you how I came to ask myself this question, and what the consequences of the answer are.

Before the dropping of the atomic bomb on Hiroshima and Nagasaki, there was the burning of Tokyo. Operation Meetinghouse, the early March 1945 raid on Tokyo that involved over 330 B-29s dropping incendiary bombs from low-altitude at night, killed roughly 100,000 people, and may have injured and made homeless an order of magnitude more. As with all statistics on the damage caused by strategic bombing during World War II, there are debatable points and methodologies, but most people accept that the bombing of Tokyo probably had at least as many deaths as the Hiroshima bombing raid, and probably more. It is sometimes listed as the most single deadly air raid of all time as a consequence.

The ruins of 1945: Tokyo, left, and Hiroshima, right.

The ruins of 1945: Tokyo, left, and Hiroshima, right.

So it is understandable that many people, including myself, point to Tokyo whenever people want to talk about Hiroshima and Nagasaki. You can’t see the atomic bombings in isolation. The practice of targeting civilian areas with massively destructive aerial bombing had already been done before. And to some, the atomic bombs were just a refinement of the art of area bombing — a more efficient means to accomplish the same ends.1

However, there are a few points that I fear get missed in that kind of equivalence. I certainly agree that the philosophy of bombing used at Hiroshima and Nagasaki wasn’t a new one. Indeed, the experience of firebombing gave a lot of guidance to the question of nuclear targeting. The goals were similar, though the people planning the atomic bombs emphasized the raw terror that they hoped such a spectacle would inspire.

But I depart from the standard comparison in two places. The first is the idea that since the atomic bombings were not original in targeting civilians, then they do not present a moral or ethical question. As I’ve written about before, I think the question of morality gets more problematic. If the atomic bombings were one-off events, rare interventions to end the war, then it might (for some) be compelling to say that they were worth the price of crossing over some kind of line regarding the deliberate burning of civilians to death en masse. But if they were instead the continuation of a well-established policy of burning civilians to death en masse, then the moral question gets much broader. The question changes from, Was it morally justified to commit a civilian massacre two times?, to Was it morally justified to make civilian massacre a standard means of fighting the war? 

I want to state explicitly that I don’t think, and I don’t want my phrasing to imply, that the answer to the above is necessarily an unequivocal “no.” There are certainly many moral frameworks that can allow for massacres (e.g. ends-justify-the-means). But I prefer to not dress this sort of thing up in euphemisms, whether we think it justified or not.  Massacre means to deliberately and indiscriminately kill people. That is what you get when you bomb densely-populated cities with weapons that cannot distinguish between civilians and members of the military. Incendiary raids and atomic bombs certainly fall in this category, whether one thinks that the circumstances required them or not.

Japanese cities destroyed by strategic bombing in World War II. More information about this map here.

Japanese cities destroyed by strategic bombing in World War II. More information about this map here.

The second place I depart is a technical one. There are several important differences between the effects of firebombing and atomic bombing. They are not, even in the case of the bombing of Japan, strictly equivalent from the point of view of their effects or their outcomes.

The Tokyo firebombing raid was a relatively slow (compared to an atomic bomb), massively-distributed attack. The Tokyo raid involved hundreds of B-29 bombers arriving and attacking over the course of several hours. Such massive groups of B-29s could be heard and tracked from a considerable distance. They spread their bombs over a large area of the city, with the goal of creating a mass conflagration that would be impossible to control. They could be fought against with interceptors and anti-aircraft guns; air-raid alarms could be sounded; civilians could flee to shelter, or outside of the city itself.  This is not to imply that any of these strategies were necessarily effective, and it does not necessarily make firebombing raids any more “humane.” But it does change the outcome quite a bit, when compared to an atomic bomb attack.

The atomic bombing raids of Hiroshima and Nagasaki were fast, near-instantaneous attacks. They involved a single B-29 weather plane in advance, and then two or three B-29s approaching the city, one with the bomb itself. This means that effective air-raid warning was minimal, because it was not possible to distinguish an atomic bomb attack from a reconnaissance or weather flight, all of which were common by that late stage in the war. (And obviously any hope of detecting an atomic bomb attack was impossible prior to Hiroshima.)

Drawing by Goro Kiyoyoshi of his memories of the Hiroshima attack. "I got on a streetcar of the Kabe line about 8:10 AM. The door was open and I was standing there. As I heard the starting bell ring, I saw a silver flash and heard an explosion over the platform on which l had just walked. Next moment everything went dark. Instinctively I jumped down to the track and braced myself against it. Putting a handkerchief to my mouth, I covered my eyes and ears with my hands."

Drawing by Goro Kiyoyoshi of his memories of the Hiroshima attack. “I got on a streetcar of the Kabe line about 8:10 AM. The door was open and I was standing there. As I heard the starting bell ring, I saw a silver flash and heard an explosion over the platform on which l had just walked. Next moment everything went dark. Instinctively I jumped down to the track and braced myself against it. Putting a handkerchief to my mouth, I covered my eyes and ears with my hands.” From Unforgettable Fire: Drawings by Atomic Bomb Survivors (1977).

The primary acute effects of the atomic bombs were blast and thermal radiation. The former travels at the speed of sound, the latter significantly faster. (The rays are transmitted at more or less the speed of light, but the intensity and duration of the thermal pulse is a more complex phenomena and unfolds over the course of several seconds.) The blast knocks down buildings. The thermal radiation heats and burns. Both contribute to the starting of fires — the thermal radiation directly (for certain materials), the blast wave indirectly by knocking over flammable materials, stoves, candles, etc. After Hiroshima there was a significant firestorm, as with incendiary bombing, but there was not after Nagasaki. There was no effective preparation for such an attack — perhaps if they had the foresight of some later Civil Defense techniques, some lives could have been saved (different shelter types did affect the fatality rates significantly, even close in to the zero point), but obviously this was not quite in the cards during the war itself, when the atomic bomb was such a novelty. There was no time for shelters, no time to flee the city, no time even for real comprehension of what was happening — a bright light followed by a crushing blast, followed by fire. For those who survived the blast and fire, there were radiation effects, if they were with a few kilometers of the epicenter. This could range from acute radiation sickness and death with several weeks, to an increased cancer risk over the course of their lives.

Are the atomic bomb effects significantly different from firebombing to warrant putting them into different ethical or moral categories? One could argue the point either way. I tend to think that they are both pretty terrible forms of suffering, but they are not identical. In many ways the atomic bombing effects were significantly worse for the people living in the target cities — all of the suffering of firebombing accelerated, with a few new terrors added into the mix, and with less warning.

Table from a 1963 Office of Civil Defense report, "Survey of the Thermal Threat of Nuclear Weapons," by Jack C. Rogers and T. Miller. These numbers are not necessarily authoritative, but they give some indication of the relative mortality rates differences I am talking about.

Table from a 1963 Office of Civil Defense report, “Survey of the Thermal Threat of Nuclear Weapons,” by Jack C. Rogers and T. Miller. These numbers are not necessarily authoritative, but lay out the situation well: atomic bombs have much higher mortality and casualty rates per square mile than firebombing, but destroy proportionally smaller amounts of area.

But the equivalence argument also misses some important differences in how deadly the atomic bombs were. The firebombing of Tokyo did, indeed, kill the most people of any air raid in history — from 80,000 to over 100,000 dead in a single raid. But the city of Tokyo had some 5 million people living in it. In the areas targeted, there were 1.5 million people living. So that means that it killed no more than 2% of the total population of the city, and no more than 7% of the people who lived in the targeted areas. The bombing of Hiroshima killed between 90,000 and 160,000 people in a city of 345,000 or so. So that is a fatality rate of 26-46%, depending on whose fatality estimates you go with. The bombing of Nagasaki killed between 39,000 to 80,000 people in a city of 260,000 people or so. So that is a fatality rate of 15-30%.

So to put it another way, the Hiroshima bombing was around 5 times more deadly than the Tokyo raid per capita, and the Nagasaki bombing was maybe 4 times more deadly. The total number dead is similar in all three cases, but the total number of people possible to kill in Tokyo was much higher than the number of people in Hiroshima and Nagasaki.

This isn’t the whole story, though. There is a subtle technical difference mixed in here. Firebombing on par with the Tokyo raid spread a moderate chance of death over a large area. The atomic bombs dropped in World War II spread a very high chance of death over a relatively small area. So depending on the target in question, the difference in fatalities might or might not matter. The Hiroshima bomb was perfectly capable of killing something like half of the city — but it was a pretty small city, compared to Tokyo. Tokyo has areas of incredibly high density, but also large areas of relatively moderate to low density.

So why does this matter? From an ethical standpoint, I’m not sure it does. The targeting of civilians for mass destruction seems to be the core ethical issue, whether you do this by means of fire, neutrons, or toxic gas. But I do think we end up underestimating the effects of the atomic bombs if we see them as exactly equivalent to firebombs. There is an error in seeing the atomic bombs as just an expeditious form of firebombing — it both overstates the deadliness of firebombing while understating the deadliness of atomic bombs.

This map gives a rough indication of the methodology used to construct the casualty estimates for a Little Boy bomb targeted on World War II Tokyo. Percentages are expected average fatality rates. The actual method used (see below) used many more gradations of difference. One can see, though, the way in which the most intense of the effects of the atomic bomb are highly localized relative to the total size of Tokyo.

This map gives a rough indication of the methodology used to construct the casualty estimates for a Little Boy bomb targeted on World War II Tokyo. Percentages are expected average fatality rates. The actual method used (see below) used many more gradations of difference. One can see, though, the way in which the most intense of the effects of the atomic bomb are highly localized relative to the total size of Tokyo. The underlying population density map of Tokyo comes from the very useful Japanairraids.org.

All of this is what led me to the question I opened with: What if, in some hypothetical alternative universe, instead of launching a firebombing raid in early March 1945, the US was able to drop the Little Boy atomic bomb onto Tokyo? What would the casualties have been for that raid?

Obviously an exact answer is not possible. But we do have population density maps of Tokyo, and we do have records on the relationship between distance from “ground zero” and percentage of population killed. There are lots of uncertainties, here, regarding the types of buildings, the differences in geography, and other things that are hard to estimate. But let’s do a rough estimation.

If we transpose the effects of Hiroshima — a 15 kiloton bomb detonated around 1,968 feet above the ground — to the population densities of Tokyo, what is the result? I don’t want to clog up the blog post with a detailed explanation of the methodology I’ve used, so I’m putting it at the end with the footnotes. The basic gist of it was this: I took a population density map of Tokyo from 1940, divided the different density areas into different layers in Photoshop, then selected radii based on bomb effects and did pixel counting. I used all of this to come up with rough minimum-maximum estimates of how many people lived in areas at different regions from the bomb blast, and then multiplied those population counts against known average fatality/casualty rate data taken from Hiroshima.

I looked at two ground zeros, to further emphasize the intense locality of a Hiroshima-sized atomic bomb attack (compared to a firebombing raid). If targeted on the moderately-dense Honjo area (which is more or less the center of the firebombing attack), one could roughly expect there to be between 213,000 and 344,000 fatalities, and between 442,000 and 686,000 injuries. This is the ground zero shown in the above image. If you move it north-west by only 1 km, though, to the more densely populated Asakusa area, the numbers change to 267,000 to 381,000 dead and 459,000 to 753,000 injured.

So if the Hiroshima bomb had been dropped on Tokyo, it probably would have destroyed less area than the March 1945 Tokyo firebombings — something like 5 square miles, compared to the 15 square miles destroyed by firebombing. However it would have killed between two and four times as many people who died in the firebombings, and injured possibly fewer or the same amount of people.

These numbers seem roughly plausible to me, even given all of the uncertainties involved, and they align with the rough guess one would make from the relative area destruction and casualty rates cited earlier. It is of note that the shifting of an atomic bomb’s aiming point can increase total casualties by several tens of thousands of people in a city the density of Tokyo; firebombing is probably not quite as dependent on any given aiming point, given how much lower the accuracy was.

Finally, it is worth noting that the Tokyo firebombing was much more fatal than most of the other firebombing raids. As the first low-altitude, massed night B-29 incendiary raid, against Japan’s highest-density city, it was especially fatal. Later raids killed, on average, orders of magnitudes less, both for the reasons given at the beginning (e.g. fleeing when you hear hundreds of B-29s in the distance), and because of much lower population densities. Had Hiroshima been firebombed, the fatalities would have certainly been much lower than the atomic bombings, because the Tokyo case is in fact an anomalously high one.

Atomic bombings may be ethically no better or worse than firebombing raids like Tokyo, but to regard them as simply an expedient form of firebombing misses a key point about their relative deadliness: If you have to pick, and you get to pick, one should choose to be firebombed, not atomic bombed — unless you know exactly where the bombs are going to go off.

Click for the full casualty calculation methodology.

Notes
  1. On this, see esp. Michael Gordin’s Five Days in August, and, perhaps,  my review of it. []
Meditations

A bomb without Einstein?

Friday, June 27th, 2014

If Albert Einstein had never been born, would it have changed when nuclear weapons were first produced? For whatever reason, I’ve seen this question being asked repeatedly on Internet forums, as odd as it is. It’s kind of a silly question. You can’t go in and tweak one variable in the past and then think you could know what the outcome would be. History is a chaotic system; start removing variables, who knows what would happen. Much less a variable named Albert Einstein, one of the most influential physicists of the 20th century, and whose importance extended well past the equations he wrote… and those were pretty important equations, at that!

1946 - Einstein Time magazine - detail

Einstein’s 1946 cover of Time magazine. The mushroom cloud is a beautifully executed combination of the Trinity and Nagasaki mushroom clouds.

On the other hand, this kind of science-fiction counterfactual can have its usefulness as a thought experiment. It isn’t history, but it can be used to illustrate some important aspects about the early history of the atomic bomb that a lot of people don’t know, and to undo a little bit of the “great man” obsession with bomb history. Albert Einstein has been associated with the bomb both through his famous mass-energy equivalence calculation (E=mc²) and because of the famous Einstein-Szilard letter to Roosevelt in 1939. On the face of it, this gives him quite a primary role, and indeed, he usually shows up pretty quickly at the beginning of most histories of the Manhattan Project. But neither E=mc² nor the Einstein-Szilard letter were as central to the Manhattan Project’s success as people realize — either scientifically or historically.

In terms of the science, E=mc² gets a lion’s share of attention, most perfectly expressed by Einstein’s portrait on the cover of Time magazine in 1946 (above) with his equation emblazoned on a mushroom cloud. A lot of people seem to think that E=mc² played a key role in the development of the bomb, that the weapon just falls out of the physics. This is wrong. The equation can help one understand why atomic bombs work, but it doesn’t really tell you how they work, or whether you would expect them to even be possible.

The way I like to put it is this: E=mc² tells you about as much about an atomic bomb as Newton’s laws do about ballistic missiles. At some very “low level” the physics is crucial to making sense of the technology, but the technology does not just “fall out” of the physics in any straightforward way, and neither of those equations tell you whether the technology is possible. E=mc² tells you that on some very deep level, energy and mass are equivalent, and the amount of energy that mass is equivalent is gigantic. But it says nothing about the mechanism of converting mass into energy, either whether one exists in the first place, or whether it can be scaled up to industrial or military scales. It gives no hints as to even where to look for such energy releases. After the fact, once you know about nuclear fission and can measure mass defects and things like that, it helps you explain very concisely where the tremendous amounts of energy come from, but it gives you no starting indications.

Eddington's famous plate of the 1919 solar eclipse, which helped confirm Einstein's theory of General Relativity. Very cool looking, and interesting science. But not relevant to atomic bombs. Source.

Eddington’s famous plate of the 1919 solar eclipse, which helped confirm Einstein’s theory of General Relativity. Very cool looking, and interesting science. But not relevant to atomic bombs. Source.

What about the rest of Einstein’s main theoretical work, both Special and General Relativity Theory? They are pretty irrelevant to bomb-making. The physical processes that take place inside atomic bombs are what physicists call “non-relativistic.” Relativity theory generally only shows its hand when you are talking about great speeds (e.g. large fractions of the speed of light) or great masses (e.g. gravitational fields), and neither of those come into play with fission bombs. You can neglect relativity when doing the math to make a bomb.1

An intelligent follow-up question might be: “well, just because relativity theory didn’t play a role in the bomb process itself doesn’t answer the question of whether it started physics on a path that led to the bomb, does it?” Without getting into a long timeline of the “science that led to the bomb,” here, I think we could reasonably summarize the situation like this: Einstein’s 1905 papers (of which E=mc² was one) did indeed play a role in the subsequent developments that followed, but perhaps not as direct a one as people think. E=mc² didn’t inspire physicists to start looking into processes that converted mass to energy — they were already looking into those through an entirely separate (and earlier) line of development, namely the science of radioactivity and particle physics. The fact that huge amounts of energy were released through nuclear reactions, for example, had already been studied closely by the Curies, by Ernest Rutherford, and by Frederick Soddy prior (but only just) to 1905.

Arguably, the most important work Einstein did in this respect was his work on the photoelectric effect (for which he was awarded the Nobel Prize in Physics for 1921), which helped establish the physical reality of Max Planck’s idea of a quantum of energy, which helped kick off investigations into quantum theory in earnest. This had a big influence on the later direction of physics, even if Einstein himself was never quite comfortable with the quantum mechanics that developed in subsequent decades.

The Hahn-Meitner-Strassman experiment apparatus, at the Deutsches Museum in Munich. My own photo.

The Hahn-Meitner-Strassman experiment apparatus, at the Deutsches Museum in Munich. My own photo.

Did any of the relativity work lead, though, down the path that eventually arrived at the discovery of fission in 1939? I don’t think so. The experiments that Hahn, Meitner, and Strassman were doing in Berlin that lead to the discovery of fission in uranium were themselves careful replications of work that Fermi had done around 1934. Fermi’s work came directly out of an experimentalist, nuclear physics context where physicists were bombarding substances with all manner of subatomic particles to see what happened. It was most directly influenced by the discovery of the neutron as a new sub-atomic particle by Chadwick in 1932. This came out of work on atomic theory and atomic modeling that was being done by Rutherford and his students from the early 1910s-1920s. And this early nuclear physics came, most directly, out of the aforementioned context of radioactivity and experimental physics of the late 19th century.

None of which has a strong, direct connection to or from Einstein’s work in my mind. They have some overlaps of interest (e.g. Bohr was a student of Rutherford’s), but the communities working on these sorts of experimental problems are not quite the same as the more theoretical circle that Einstein himself worked in.2 If we somehow, magically, removed Einstein’s early work from the equation here, does the output change much? There would be some reshuffling, probably, but I sort of think that Rutherford would still be doing his thing anyway, and from that much of the other work that led to the bomb would eventually come out, even if it had a somewhat different flavor or slightly different timeline.

My least favorite way of depicting the fission process, where energy (E) is a magic lightning bolt coming out of the splitting atom. In reality, most of the energy comes in the form of the two fission products (F.P. here) repelling from each other with great violence. Source.

This is my least-favorite way of depicting the fission process, where energy (E) is a magic lightning bolt coming out of the splitting atom. In reality, most of the energy comes in the form of the two fission products (F.P. here) repelling from each other with great violence. Source.

Do you even need to know that E=mc² to make an atomic bomb? Perhaps surprisingly, you don’t! There are other, more physically intuitive ways to calculate (or measure) the energy release from a fission reaction. If you treat the fission process as being simply based on the electrostatic repulsion of two fission products, you get essentially the same energy output in the form of kinetic energy. This is how the physics of fission is often taught in actual physics classes, because it gives you a more concrete indication of how that energy is getting released (whereas E=mc² with the mass-defect makes it seem like a magical lightning bolt carries it away). There are other more subtle physical questions involved in making a bomb, some of which have Einstein’s influence on them in one way or another (e.g. Bose–Einstein statistics). But I think it is not totally crazy to say that even if you somehow imagine a world in which Einstein had never existed, that the physics of an atomic bomb would still work out fine — Einstein’s specific technical work wasn’t central to the problem at all. We also have not brought up the question of whether without Einstein, relativity in some form would have been discovered anyway. The answer is probably “yes,” as there were people working on similar problems in the same areas of physics, and once people started paying a close attention to the physics of radioactivity they were bound to stumble upon the mass-energy relationship anyway. This isn’t to denigrate or underestimate Einstein’s influence on physics, of course. What makes Einstein “Einstein” is that he, a single person, pulled off a great number of theoretical coups all at once. But if he hadn’t done that, there’s no reason to think that other people wouldn’t have come up with his theoretical insights individually, if slightly later.

A postwar re-creation of the genesis of the Einstein-Szilard letter.

A postwar re-creation of the genesis of the Einstein-Szilard letter.

What about Einstein’s most direct role, the famous Einstein-Szilard letter of 1939 that influenced President Roosevelt to set up the first Uranium Committee? This is a tricky historical question that could have (and may at some point) an entirely separate blog post relating to it. Its writing, contents, and influence are more complex than the standard “he wrote a letter, FDR created the Manhattan Project” understanding of it that gets boiled down in some popular accounts. My feeling about it, ultimately, is this: if the Einstein-Szilard letter hadn’t been written, it isn’t clear that anything would be terribly different in the outcome in terms of making the bomb. Something like the Uranium Committee might have been started up anyway (contrary to popular understanding, the letter was not the first time Roosevelt had been told about the possibility of nuclear fission), and even if it hadn’t, it isn’t clear that the Uranium Committee was necessary to end up with a Manhattan Project. The road from a fission program whose primary output was reports and a fission program whose primary output was atomic bombs was not a direct one. By early 1941, the Uranium Committee had failed to convince scientist-administrators that atomic bombs were worth trying to build. They had concluded that while atomic bombs were theoretically feasible, they were not likely to be built anytime soon. Had things stayed there, it seems unlikely the United States would have built a bomb ready to use by July/August 1945.

The “push” came from an external source: the British program. Their MAUD Committee (an equivalent of the Uranium Committee) had concluded that a nuclear weapon would be much easier to build than the United States had concluded, and sent an emissary (Mark Oliphant) to the United States to make sure this conclusion was understood. They caught Vannevar Bush’s ear in late 1941, and he (along with Ernest Lawrence, Arthur Compton, and others) wrested control of the uranium work out of the hands of the Uranium Committee, accelerated the work, and morphed it into the S-1 Committee. The name change is significant — it is one of the more vivid demonstrations of the increased degree of seriousness with which the work was taken, and the secrecy that came with it. By late 1942, the wheels for the full Manhattan Project were set into motion, and the work had become a real bomb-making program.

Einstein wasn’t involved with any of the later work that actually led to the bomb. He almost was, though: in late 1941, Bush considered consulting Einstein for help on the diffusion problem, but opted not to push for it — both because Einstein wasn’t regarded as politically reliable (he had a fat FBI file), and his approach to physics just wasn’t very right for practical problems.3 Bush decided that Einstein would stay out of the loop.

Usual, rare anti-Nazi propaganda postcard from 1934, showing Hitler expelling Einstein from Germany, titled "The Ignominy of the 20th Century." It is one of the most blatant visual renderings of Einstein as a "scientific saint." Source.

Unusual, rare anti-Nazi propaganda postcard from 1934, showing Hitler expelling Einstein from Germany, titled “The Ignominy of the 20th Century.” It is one of the most blatant visual renderings of Einstein as a “scientific saint.” Source.

Let’s sum it up. Did Einstein play a role in the creation of the atomic bomb? Of course — his physics isn’t irrelevant, and his letter to Roosevelt did start one phase of the work. But both of these things are less prominent than the Time-magazine-cover-understanding makes them out to be. They weren’t central to what became the Manhattan Project, and if you could somehow, magically, remove Einstein from the equation, it isn’t at all clear that the atomic bomb wouldn’t have been built around the time it actually was built. I don’t think you can really credit, or blame, Einstein for the atomic bomb, in any direct fashion. Einstein did play a role in things, but that role wasn’t as crucial, central, or direct as a lot of people imagine. If you could magically drop him out of history, I think very little in terms of atomic bombs would have been affected.

So why does the Einstein and the bomb myth persist? Why does everybody learn about the Einstein letter, if it wasn’t really was sparked the Manhattan Project? There are two answers here, I think. One is that Einstein was, even before the war, one of the best-known, best-recognized physicists of the 20th century, and was synonymous with revolutionary science and genius. Having him “predict” the atomic bomb with equations in 1905 — 40 years before one was set off — is the kind of “genius-story” that people love, even if it obscures more than it enlightens. It also has a high irony quotient, since Einstein was forced to flee from Germany when the Nazis took power.

But there’s another, perhaps more problematic aspect. In many early copies of the Smyth Report that were distributed by the government, copies of the Einstein letter were mimeographed and loosely inserted. The magnification of Einstein’s role was purposefully encouraged by the government in the immediate period after using the weapon. (And it was even a convenient myth for Einstein, as it magnified his own importance and thus potential influence.) Hanging the atomic bomb on Einstein’s head was an act of self-justification, of sorts. Einstein was the world’s greatest genius in the eyes of the public, and he was a well-known pacifist, practically a scientific saint. After all, if Einstein thought building a bomb was necessary, who could argue with him?

Notes
  1. As Robert Serber puts it: “Somehow the popular notion took hold long ago that Einstein’s theory of relativity, in particular his famous equation E = mc², plays some essential role in the theory of fission. Albert Einstein had a part in alerting the United States government to the possibility of building an atomic bomb, but his theory of relativity is not required in discussing fission. The theory of fission is what physicists call a non-relativistic theory, meaning that relativistic effects are too small to affect the dynamics of the fission process significantly.” Robert Serber, The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb (University of California Press, 1992), 7. []
  2. For a good, non-teleological, non-bomb-centric approach to the context of 19th- and 20th-century physics, Helge Kragh’s Quantum Generations: A History of Physics in the Twentieth Century (Princeton University Press, 2002), is excellent. []
  3. Einstein wasn’t entirely a head-in-the-clouds physicist, of course. He worked at the patent office, and as Peter Galison has written about, even his famous thought experiments were often motivated by experience with practical problems of time synchronization. And he did help invent a refrigerator with Leo Szilard. But his work on diffusion physics was too abstract, too focused on first-principle analysis, for use in producing a practical outcome. []
Redactions

Would the atomic bomb have been used against Germany?

Friday, October 4th, 2013

If the atomic bomb had been ready earlier in World War II, would it have been used against Nazi Germany? This is one of the great atomic “what if’s” — a hypothetical, counter-factual historical question that obviously can’t be answered because that’s not how history worked out, we can’t reshuffle the past around, and so on. Anything overtures in such a direction are just speculation. But it can be informed speculation — and, more importantly, it can highlight little-known aspects of history. And that, in my mind, makes it worth indulging in, at least on a blog.

The question is an interesting one for numerous reasons. At its heart, it gets at the question of how contingent all of this was. The primary factor that determined when the first atomic bombs were ready for use was when the serious program of their production started. If the Americans had been convinced in 1940, rather than 1941, that an atomic bomb was worth seriously pursuing, then the Gadget might have been ready by July 1944, not July 1945. Could they have been convinced that early on? I see no reason why not — the British scientists had drawn that conclusion by then.

Allied troops disassembling the German experimental research reactor at Haigerloch.

Allied troops disassembling the German experimental research reactor at Haigerloch.

Up until early 1944, the bomb was still talked about as if it were going to be a deterrent against Germany. By August 1943, for example, Vannevar Bush was still reporting to Roosevelt that the Germans might be ahead, or at least neck-and-neck in the “race” for the bomb:This may result in a situation where it will be necessary for us to stand the first punishing blows before we are in a position to destroy the enemy.” By early 1944, Groves had decided that the Germans having a bomb was “unlikely,” but that it still needed to be held out as a possibility. By late 1944, it was clear, from the Alsos mission, that Germany was nowhere near an atomic bomb — and indeed, they soon learned that the German program was in 1945 not even as far as where the Americans had gotten by the end of 1942. I put this out just as context for their thinking. Over the course of late 1943 through 1944, the bomb shifted from being a deterrent to a first-strike weapon — a weapon that was meant to be used, not held in reserve. So who would it strike?

The very earliest discussion of targets of any sort was held in May 1943. As the last item of a much longer meeting, talking about all sorts of other matters (like spreading around fake stories about what was going on at Los Alamos, E.U. Condon’s resignation from the project, and construction of the various enrichment and production plants), a group composed of Groves, Vannevar Bush, James B. Conant, Admiral William Purnell, and Major General Wilhelm Styer had this discussion:

The point of use of the first bomb was discussed and the general view appeared to be that its best point of use would be on a Japanese fleet concentration in the Harbor of Truk. General Styer suggested Tokio but it was pointed out that the bomb should be used where, if it failed to go off, it would land in water of sufficient depth to prevent easy salvage. The Japanese were selected as they would not be so apt to secure knowledge from it as would the Germans.1

This has sometimes been cited as evidence that Japan was “always” the target. Personally, I think this seems like too loose of a discussion to draw big, concrete conclusions from. It was still over two years before the first atomic bomb would be ready, and, again, it is tacked on to a much longer meeting that is concerned with much more basic, much more practical things, like whether J. Robert Oppenheimer will get an administrative assistant assigned to him. But, still, it’s a data point. Note that the context, here, of choosing Japan over Germany is reflective of how uncertain they are about the bomb itself: they are worried that the first one will be a complete dud, and so their choice here is that if a dud were to land in Germany, it would be more dangerous thing than if it were to land in Japan.

Note that “the Harbor of Truk” (Chuuk Lagoon) is not a target on the Japanese home islands — it is in Micronesia, far south of the Japanese mainland, north of New Guinea. During World War II it was the Japanese equivalent of Pearl Harbor. It was a purely military, tactical target, not a strategic one. And by the time an atomic bomb was ready, it had been made irrelevant by Allied attacks and isolation (though it was still under Japanese occupation).

The first concrete discussion of targets came in the spring of 1945. These are the famous “Target Committee” meetings at Los Alamos which discussed what kind of target criteria they were using, what cities might fit it, and so on. Grim business, but entirely focused on Japan, in part because by that point it was clear that Germany’s defeat was imminent.

An elderly General Groves. This is from a fairly later period — 1967 or so. From the AIP Emilio Segrè Visual Archives, George Tressel Collection.

An elderly General Groves. This is from a fairly later period — 1967 or so. From the AIP Emilio Segrè Visual Archives, George Tressel Collection.

Is there any evidence that anyone in power would have considered atomic bombing Germany, though, had they the ability? The only insight I’ve found on this comes from a postwar interview that General Groves gave, sometime in the early 1960s:2

REPORTER: General Groves, could we go back for a minute. You mentioned in your book [Now it Can Be Told] that just before the Yalta Conference that President Roosevelt said if we had bombs before the European war was over he would like to drop them on Germany.3 Would you discuss this?

GROVES: At the conference that Secretary Stimson and myself had with President Roosevelt shortly before his departure, I believe it was December 30th or 31st of 1944, President Roosevelt was quite disturbed over the Battle of the Bulge and he asked me at that time whether I could bomb Germany as well as Japan. The plan had always been to bomb Japan because we thought the war in Germany was pretty apt to be over in the first place and in the second place the Japanese building construction was much more easily damaged by a bomb of this character than that in Germany. I urged President Roosevelt that it would be very difficult for various reasons.

The main one was that the Germans had quite strong aerial defense. They made a practice, as every nation does, that when a new plane came into the combat area, that they would run any risk that they could to bring such a plane down so that they could examine it and see what new ideas had come in so that they could make improvements and also would know the characteristics of the plane so that they could prepare a better defense against it. We had no B-29’s in Europe. If we had sent over a small squadron or group as we did against Japan of this type, everyone of them would have been brought down on the first trip to Germany. If they hadn’t been, it would have been through no lack of effort on the part of the Germans.

The alternative would be to bring a large number of B-29’s over to to England and that would have been a major logistical task and the other possibility would have been to have used a British plane which would not have been a bit pleasing to General Arnold and also would have created a great many difficulties for our general operation because then it would be an Allied operation with the United States furnishing the bombs and everything connected with it but using a British plane and a British crew to actually drop the bomb and it would have raised a tremendous number of difficulties.

And difficulties like that — while you say you should be able to handle that — you can but in a project of this character there are so many little things, each one of them key, that you can’t afford to throw any more sand into the wheels that you can help.

The bombing of Germany with atomic bombs was, I would say, never seriously considered to the extent of making definite plans but on this occasion I told the President, Mr. Roosevelt, why it would be very unfortunate from my standpoint, I added that of course if the President — if the war demanded it and the President so desired, we would bomb Germany and I was so certain personally that the war in Europe would be over before we would be ready that you might say I didn’t give it too much consideration.

Now this is an interesting detail, is it not — that FDR himself was interested in whether they could drop an atomic bomb on Germany? One has to always question postwar recollections, especially the General’s, but this has the ring of authenticity to it. I don’t think Groves would fabricate memories of conversations with Roosevelt. At this meeting, Groves had thought that the first uranium bomb (Little Boy) would be ready by late July, and that the first plutonium bomb would be ready by early August — far too late for use in the European war. But it is worth contemplating Roosevelt’s intentions. Did he really want to drop this bomb, or was he trying to figure out what exactly the USA’s chips were before entering into discussions with the Soviets? Would Roosevelt have made the same concessions to the Soviets that he ended up making, had he thought the US had an atomic bomb at the ready? Would he have insisted that the Soviets enter the Pacific war? More hypotheticals than I can deal with, but it does add an interesting wrinkle to the discussion.

The B-17 bomber (left) and the B-29 bomber (right). Source.

The B-17 bomber (left) and the B-29 bomber (right). Source.

Groves’ argument against using a bomb in the European theatre is also interesting. Essentially he is saying that the choice not to deploy B-29s in Europe, and the choice of the B-29 as the weapon for the atomic bomb (a decision made in late 1943), had profound practical consequences. It is easy to forget that the first atomic bombs could not be dropped out of just any old plane. They were huge by the standards of World War II: the Fat Man bomb was a single, 10-foot-long, 5-foot-wide weapon that weighed over 5 tons. Neither the B-17 nor the B-24 could carry such a load in weight alone, much less in one fat bomb. The Little Boy boy bomb was just as long, weighed a little less, and did not have as large a diameter. It was also a bit over the maximum load ever carried by those other planes. The British Avro Lancaster bomber could have carried Little Boy, though — the Tall Boy and Grand Slam bombs were larger than Little Boy, though with much smaller diameters than Fat Man. My guess is that the Lancaster’s bay was too narrow for Fat Man.4

Does one buy Groves’ reasons? Part of me is suspicious that his justification has the feel of a post facto justification to it — it’s just a little too thought out for a quick reply to Roosevelt. If I were to guess, it was the fact that he didn’t expect the bombs to be ready anytime soon, and didn’t want the obligation of trying to get one ready for use against Germany, that really was the reason for him not wanting FDR to think that the bomb might be ready for that piece of the war. Having one ready to drop on Japan by August 1945 proved to be a tough job as it was.

Loading Fat Man

Was racism a factor? This sometimes gets asked as well. One of the tricky things about racism is that it only rarely factors into reasoning explicitly. I’ve seen nothing in the discussions of the people in charge of target selection that make me think that racism played any kind of overt role in the decisions they made — at least, in the sense that they would have dropped the bomb on the Japanese but would not have dropped it on the Germans. It doesn’t mean it didn’t, of course — just that I haven’t seen any real evidence of it. This is an entirely separate issue from whether racist dehumanization was encouraged for the populace and the troops (it obviously was). But, again, I don’t see any evidence to support the idea that the Americans would not have used atomic weapons against the Germans because they were whites, but would have used them against the Japanese because they were not. The Allies clearly were willing to massacre German civilians, as they did drop firebombs on several German cities, though that obviously does not tell the whole story.

So what’s the take-away answer? The long and short of it is, of course, that they didn’t have the bombs ready to use in the European theatre, knew they wouldn’t from fairly early on, and so never took the time to try and clarify the logistical issues that would have made it practicable. But Roosevelt’s question to Groves does leave open the possibility that they might have done it, if all of those things had turned out differently.

Notes
  1. Minutes of the Military Policy Meeting (5 May 1943), Correspondence (“Top Secret”) of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 3, Target 6, Folder 23, “Military Policy Committee, Minutes of Meetings.” []
  2. Leslie R. Groves interview with Fred Freed (n.d., ca. 1963), National Archives and Records Administration, RG 200, Box 4, “Groves, Leslie.” []
  3. “It was at the same conference that Mr. Roosevelt informed me if the European war was not over before we had our first bombs he wanted us to be ready to drop them on Germany.” Groves does not elaborate on this in the book at all. Leslie Groves, Now it Can Be Told (New York: Harper, 1962), 184. []
  4. And the Gadget was pretty snug inside the Fat Man ballistic casing — I don’t see them reducing the diameter. []
Meditations

What If Truman Hadn’t Ordered the H-bomb Crash Program?

Monday, June 18th, 2012

The debate over the hydrogen bomb is one of my favorite Cold War episodes. I keep coming back to it, both on the blog and in my research. I’d posit that it is in many ways a lot more interesting than the debates about Hiroshima and Nagasaki. Why? Because at the time of the Second World War, there was actually very little debate about Hiroshima and Nagasaki. You basically had the Franck Report and the Targeting Committee; the former said, “don’t drop it,” and the latter replied, “who cares what you think? We’re dropping it.” As many have pointed out, the whole idea that there was a conscious “decision to drop the atomic bomb” is a bit off — it doesn’t appear that anybody who had the authority to drop the bomb agonized over the question before dropping it. What agonizing there was mostly came after the fact.

The H-bomb was something else, though. This was a technical possibility that had been seen long before the weapon was capable of being built, and there actually was a period of serious behind-the-scenes and later public debate over whether it should be built, in an era where the potential guilt of Hiroshima and Nagasaki was still palpable. A lot of scientists saw the hydrogen bomb as an opportunity for the moral debate they never had about the atomic bomb, and that makes it, to me, a much more interesting co-mingling of visions of the past and fears of the future.

The ultimate “What If? of the atomic bomb is, “what if they didn’t drop the bomb?” The ultimate “What If?” of the H-bomb is, what if Truman hadn’t ordered the crash program in late January 1950? 

The common Cold War argument was one of technological inevitability: if the H-bomb could be built, it would be built. This was then mixed with an existential plea: it would have been “intolerable” for the USSR to have an H-bomb and the USA not to. But let’s shelve these common arguments for a minute, because, while interesting, they obscure a somewhat more basic factual question about what would have happened. I think that the incredible US superiority in both fission bombs and in delivery mechanisms would have easily deterred an H-bomb attack from the USSR, personally, and there are lots of ways to imagine the could/would transition could be avoided or stalled, but frankly, I think both of those questions are actually irrelevant to what would have occurred. 

There’s a brief timeline that we all have to know to be on the same page here, so let’s just throw it out in bulleted form:

  • August 1949: USSR tests its first bomb in a test the US dubs “Joe-1.” The US detects it in September. Secret debate begins within US government over whether an H-bomb should be built. Debate leaks to public by end of 1949.
  • Late January 1950: Truman announces publicly that the Atomic Energy Commission should work to build an H-bomb.
  • March 1951: Edward Teller and Stanislaw Ulam figure out how to make a multi-megaton H-bomb.
  • May 1951: The basic principle of the Teller-Ulam design is tested at the Greenhouse GEORGE test in the Pacific Ocean. Also tested is Greenhouse ITEM, a “boosted” bomb whereby a tiny amount of fusion fuel is used to improve the efficiency of a fission bomb. “Boosted” bombs greatly increase the yield of existing weapons and/or allow you to make more weapons with less fissile material.
  • November 1952: The US tests its first Teller-Ulam style H-bomb, Ivy MIKE (10 Mt). It also tests Ivy KING, the largest pure-fission weapon ever built (500 kt; half a megaton). The Ivy MIKE device is a proof-of-concept; it weighed over 50 tons. (A handful of  potentially-deliverable prototypes were made based on the design, but it isn’t clear whether they were considered reliable.)
  • August 1953: The USSR tests “Joe-4,” a nuclear weapon that involves some fusion reactions but was not a “true” H-bomb. It was a very big bomb (400 kt, still less than the all-fission Ivy KING), but the design could not be scaled into the megaton range. Still, a big bomb, and it could be dropped from existing Soviet bombers.
  • March 1954: The US begins a test series of deliverable high-yield thermonuclear weapons, Operation Castle. Castle BRAVO, the first test in the series, was considerably larger in yield than was expected (15 Mt) and was one of the worst radiological accidents in US testing history. The US now has weaponized H-bombs in the multi-megaton range.
  • November 1955: The USSR tests its own multi-megaton H-bomb for the first time (RDS-37); it is deliverable.

That’s the history we’re really concerned with. Herbert York, in 1975, wrote an article in Scientific American about this question, the gist of which was later published as a book, The Advisors: Oppenheimer, Teller, and the Superbomb (San Francisco: W. H. Freeman, 1976). Most of the book and article concern the October 1950 report by the AEC’s General Advisory Committee which was unfavorable to the idea of building the H-bomb and led to Oppenheimer’s security hearing some years later. But what I really love about the Scientific American article, as opposed to the book that came out, are his illustrated timelines.1

The above is a modified version of the Scientific American timeline, and describes the events shown up above in bullet points. I’ve added a few small things to it — the period of the H-bomb debate itself (the endpoint is Truman’s announcement; the debate technically goes on after that though it is a pretty done deal from a policy perspective), and the asterisk on the US “side” of the timeline shows when the US learned the Teller-Ulam idea, and the asterisk on the Soviet side is supposedly when the USSR figured it out for themselves. (Exactly when the Soviets actually figured it out, and how, is a matter of some continuing dispute.) The colors indicate the bomb type as indicated by the chart (they are not as distinct in the scan as the original), and the size of the circles indicate relative yield.

I like two things about this timeline. The first is that it shows how relatively close these events were to one another — two years (say, 1950 to 1952, or 1952 to 1954) seems like a long time until you stack it up like this, when it seems almost immediate. But the other thing comes what York (or, rather, the graphics editors at Scientific American, who worked quite independently from the authors at this period of time) does next: he proposes alternate possibilities.

Let’s imagine, says, York, that Truman doesn’t order an H-bomb built. What’s the most probable outcome? Here’s what he gives in response (I’ve modified this to fit onto the “original” timeline above; in York’s it is a series of branching timelines):

In York’s view, this “most probable alternative world,” without the Truman decision, the US would still have developed ITEM (the “boosted” bomb) and KING (the all-fission bomb, which he says would have likely even been tested earlier, since the tempo of Operation Ivy was set by the time it took to get MIKE together). Let’s imagine the Soviets still tested “Joe-4,” which was, again, not a “true” multi-megaton H-bomb. York thinks that at that point, the US would have then initiated a “crash” H-bomb project, and pulled off a GEORGE-like test in late 1954, and probably a full-scale H-bomb in 1955 or 1956. (The MIKE/BRAVO distinction is whether it would have been liquid or solid fueled; hard-to-deliver or easier-to-deliver.)

Interestingly, York also thinks that the Soviets’ development of a multi-megaton H-bomb would have been delayed. Why? Because in his view they got a lot of “stimulus” from the 1952 test, knowing that it was possible to work in the first place. Once you know something is achievable, for whatever reason, you end up finding the solution pretty quickly. (This is not unlike, but not quite the same thing, as the technological inevitability argument.) There is also (but York doesn’t propose this) the possibility that the MIKE shot more directly helped the USSR in the way of fallout, as was speculated by Daniel Hirsch and William G. Mathews in the Bulletin of the Atomic Scientists awhile back now.2 The Soviets later claimed that they bungled the fallout analysis, but one never really knows.

So in York’s “most probable” scenario, the US still would have had a real H-bomb well before the USSR. It’s hard to see “Joe-4” as creating a strong strategic imbalance, especially since the US still would have had a bomb that big ready to go (KING).  OK, York says, maybe that’s optimistic. What’s the worst possible scenario? Another timeline:

In this timeline, we use the “real world” Soviet testing timeline with the “most probable” US reaction timeline. The result is that the Soviets have their first H-bomb at just about the same time that the US would have had one. That is, even in the worst-case scenario, the US and the USSR more or less have multi-megaton H-bombs at the same time. Not much imbalance to be held, especially if you take it into account that the US still had a huge advantage in fission weapons (3057 to 200 in 1955) and deliverability (bases in close proximity, long-range bombers).

All of these scenarios, of course, presume that the USSR would have soldiered on ahead with the H-bomb even if the US had renounced building it. That is, these are by definition all pessimistic scenarios — and none of them are that bad. One wonders what truly optimistic scenarios would have looked like!

The first “true” Soviet H-bomb test, 1955.

I like this way of using the timelines, though it flattens a lot. Would Teller and Ulam have come up with the Teller-Ulam idea without the Truman “crash” program? There’s a lot to unpack there in terms of chronology — they didn’t come up with it by just sitting around idly. Did the “crash” program really speed up development? A big, deep, difficult question. (In other words, are the asterisks on the modified “real” timeline actually fixed positions or are they relative to other things, and if so, to what?)

But still, even while this timeline approach doesn’t quite cover all the bases, I still think it helps us play with the dates here a bit better, and visually play with the possibilities (“most probable” and “worst possible”) in a provocative way. The “flattening” effect of the timeline is by design. I’m all for thick description (as you can tell), but sometimes there’s an analytical advantage to being able to smooth things out to try and see the big pictures.

I’m more or less convinced that the world wouldn’t have ended if Truman hadn’t ordered the H-bomb’s development. Heck, even if the USSR did have exclusive possession of multi-megaton H-bombs, I still don’t see it affecting the strategic situation in a completely “intolerable” way — I don’t see the USA ever thinking its fission deterrent wasn’t able to deter. But the beauty of this way of thinking about it is that you don’t even have to have that discussion, really, because it’s not clear that possibility was ever on the table.

Notes
  1. Herbert York, “The Debate over the Hydrogen Bomb,” Scientific American 233 (October 1975), 106-113. A copy is reprinted in York’s Arms and the Physicist, for those who don’t have access to Scientific American back issues. []
  2. Daniel Hirsch and William G. Mathews, “The H-bomb: Who Really Gave Away the Secret?Bulletin of the Atomic Scientists 46, no. 1 (January 1990), 22-30. []