The Doomsday Machine

by Daniel Ellsberg

  Of course, none of these officials, civilian or military, ever hoped or perhaps expected circumstances to arise that would compel them to carry out any of these plans. But they also knew the chances of that occurring were more than zero. It was always a possibility, a risk—hopefully a remote one.

  At the same time,202 they did not see themselves as presiding over a Doomsday Machine that might kill nearly everyone.† Nevertheless, the risk the presidents and Joint Chiefs were consciously accepting, however small they saw the probability of carrying out the SIOP, involved the possible ending of organized society—the very existence of cities—in the northern hemisphere, along with the deaths of nearly all its human inhabitants.

  As the British historian Edward P. Thompson summed it up somberly, this outcome would not (probably) mean the “extermination of all life.” It would “mean only the extermination of our civilization.203 A balance sheet of the last two millennia would be drawn, in every field of endeavor and of culture, and a minus sign be placed before each total.”

  From 1961 on, I thought of that decision-making by responsible authorities in the United States and its NATO allies, as well as in the Soviet Union, in the same way that I thought of the Vietnam War eight years later: as something that needed to be resisted204 but that remained to be understood.† As I studied over subsequent decades the history of the nuclear era, I learned that the prospect of a threat to the existence of civilization and even our species—not only in the northern hemisphere—had been foreseen, in great secrecy, at the very onset of the Manhattan Project.

  Specifically, the possibility of thermonuclear weapons, a thousand times more powerful than the fission weapons (and ultimately cheaper and more numerous), loomed in the minds of the Manhattan Project scientists from the beginning. It was seen eventually by some of them as a challenging and exciting prospect, both inevitable and desirable; by others, in anguish, as a danger they urgently desired (but failed) to prevent.

  However, at the very same time—in fact, on the same afternoon in July 1942—that the top theoretical minds of the Manhattan Project were introduced to the prospect of H-bombs as a result of their efforts, they were exposed to the possibility of a much less likely but more imminent and almost unimaginably more serious threat to all life on the planet. Secretly, they accepted that risk.

  This little-known story (in the next chapter) reveals something about actual decision-making under uncertainty at high levels, especially under cover of secrecy, that we humans are understandably resistant to recognizing in our leaders. It reveals the original readiness to gamble with nuclear disaster—a willingness to undertake small and sometimes not-so-small risks of ultimate catastrophe—that leading officials in nuclear superpowers have been exhibiting ever since. It is not good news.

  CHAPTER 17

  Risking Doomsday I

  Atmospheric Ignition

  As we have seen, the creation of a nuclear Doomsday Machine depended on a willingness to regard cities as legitimate targets for mass destruction; that was fully accepted by our ally, Britain, as early as 1942, and by our own leaders and air force by 1945. But the construction and maintenance of such a machine also drew on a willingness, at least on the part of certain human beings, to undertake vast, even incalculable risks that went far beyond the potential of “killing a nation.” This propensity was demonstrated before the first atomic bomb was tested on living targets.

  In the late winter of 1941, Enrico Fermi passed on to Edward Teller his thoughts about the possibility of a fusion bomb a thousand times more powerful than the fission bomb they were about to consider. To cause atoms of the lightest element, hydrogen, to fuse together, thereby releasing a vast amount of energy, would require extraordinarily intense heat. Within the heart of the sun, fusion of hydrogen was self-generated by the ongoing heat and pressure of the sun itself. On earth, if it were possible at all, the fusion of hydrogen would require a fantastic amount of heat and pressure to start the process. But an atom bomb—which depended for its energy on splitting, or fissioning, the atoms of the heavy element uranium—might do the job.

  This discussion with Fermi lighted a fire in Teller’s mind that never subsided. The pursuit of this obsession so consumed him during the Manhattan Project that he was shunted aside by Robert Oppenheimer to a subproject on “future superweapons” and didn’t contribute much to the actual project of developing an atomic weapon before the end of the war.

  It was on the second day of the first meeting of the proto–Manhattan Project, July 7, 1942,205 in a locked classroom at the University of California, Berkeley, with heavy wire screens on the windows to keep out intruders, that Teller covered a blackboard with his calculations on the process that might lead to the ignition of a thermonuclear fusion weapon.

  First, he laid out the process understood in principle by all those in attendance, starting with the fission by a single neutron of one atom of U-235, which, in splitting, would emit two or more neutrons. That would in turn start a chain reaction of successive fissioning and emissions that would, in milliseconds, cause an explosion a thousand times more powerful than the blast of a ton of TNT. That was supposedly the end result their main project was aiming for.

  But the point of Teller’s presentation, triggered by his conversation with Fermi, was a calculation of the heat that would be built up in this process. It would be enough, he proposed to show, that the resistance to the fusion of two or more atoms of hydrogen would be overcome, leading to the emission of energy another thousand times greater (a million times that of TNT). His figures on the board did show that.

  But to these assembled minds it also showed something else, something Teller himself quickly pointed to. The scientists looked at the blackboard scribblings with a wild surmise. Heat that intense, greater than that at the center of the sun, would not only fuse hydrogen atoms. It would break the Coulomb barrier between atoms of hydrogen in water and nitrogen in the air. It would ignite virtually instantaneously all the hydrogen in the oceans and set the air around the globe afire. The earth would blaze for less than a second in the heavens and then forever continue its rounds as a barren rock.

  None of them, coming together in Berkeley, had doubted the theoretical feasibility of an atomic explosive. The problems, possibly insurmountable at least in time for practical use in World War II, were technical: for example, could the mass be held together long enough for the fission chain to generate a full explosion? Now it appeared that the practical challenge of making the bomb was not the only issue. Making it workable might not be such a good idea.

  They began to go over the stages of Teller’s calculations. Before long they discovered a mistake. He had omitted consideration of one part of the process that bore, critically, on the speed of cooling: the transmission of heat to the atmosphere. Still, these corrections did not eliminate the possibility that the feared reaction might still occur.

  Among those present for this presentation was Hans Bethe, who was the greatest theoretical physicist among the group, and whose later Nobel Prize was precisely for his work on the thermonuclear reactions in the sun. His initial instinct was that this result was “impossible.”

  However, others didn’t come out with that result. (“Certainty,” Nuel Phar Davis wrote in his account of this episode, “is a state of mind206 based on not having to depend on someone else’s calculations.”) Fermi, in particular, the greatest experimental physicist present, did not agree with Bethe’s assurance of impossibility. Eventually Oppenheimer concluded that Arthur H. Compton, in charge of the whole project, needed to be told of this danger at once. Meanwhile, everything had to be put on hold. But Compton was on vacation with his family at a lake in Michigan. Oppenheimer managed to reach him by phone and, in an anxious voice, told Compton that he must come to see him immediately. He couldn’t tell him why. They agreed that Oppenheimer would take the next available train. (Scientists essential to the project were forbidden by government orders to travel by plane, for safety reasons.) What happened
next was recounted by Compton in his memoir:

  I’ll never forget that morning.207 I drove Oppenheimer from the railroad station down to the beach looking out over the peaceful lake. There I listened to his story. What his team had found was the possibility of nuclear fusion—the principle of the hydrogen bomb. This held what was at the time a tremendous unknown danger. Hydrogen nuclei, protons, are unstable, for they could combine into helium nuclei with a very high temperature. But might not the enormously high temperature of an atomic bomb be just what was needed to explode hydrogen? And if hydrogen, what about the hydrogen of sea water? Might the explosion of an atomic bomb set off an explosion of the ocean itself?

  Nor was this all. The nitrogen in the air is also unstable, though in less degree. Might it not be set off by an atomic explosion in the atmosphere?

  These questions could not be passed over lightly. Was there really any chance that an atomic bomb would trigger the explosion of the nitrogen in the atmosphere or of the hydrogen in the ocean? This would be the ultimate catastrophe. Better to accept the slavery of the Nazis than to run a chance of drawing the final curtain on mankind!

  Let’s step back for a moment and consider that last proposition. It seems sensible enough, one might even say obvious. Yet in the countless books about the Nazis and World War II, I don’t believe that there is a comparable statement to be found anywhere, in any official record, memoir, or scholarly history. Nor in a newspaper editorial or letter to the editor. Something worse than Nazi occupation?

  Being enslaved by Nazis was actually not a near-term danger for Americans, but it was for their wartime allies, the British and Russians. In June 1942, just before the six-month battle of Stalingrad was to begin, a Nazi victory in Russia looked more than possible, on top of their success in occupying all of Europe. And at the time of Compton’s judgment, the Nazis had begun the process of murdering two million Polish and six million Jewish civilians in their occupied lands, along with twenty-seven million Soviet soldiers and civilians. Could there really be something worse, something so bad that “a chance” of it was worse than accepting the slavery of the Nazis?

  Well, yes. Compton’s instant judgment was that what they might be bringing about—the possibility of ending life on earth—was such a prospect, one they should not risk at any cost.

  Strikingly, Adolf Hitler’s own reaction to this possibility was not different. Just weeks prior to this, in June 1942, his minister of armaments, Albert Speer, was confirming Hitler’s view that there was “not very much profit” in pursuing an atom bomb project during the war, mainly because it would not be successful within Hitler’s two-year deadline for victory, but also for another reason:

  Actually, Professor Heisenberg208 had not given any final answer to my question whether a successful nuclear fission could be kept under control with absolute certainty or might continue as a chain reaction. Hitler was plainly not delighted with the possibility that the earth under his rule be transformed into a glowing star.

  Following this discussion, Speer reported, “on the suggestion of the nuclear physicists we scuttled the project to develop an atom bomb … after I had again queried them about deadlines and been told that we could not count on anything for three or four years.”

  In ignorance of this German decision that month against a bomb project, and facing the possibility that earth might become forever a barren rock after a very brief glow, Compton and Oppenheimer “agreed there could be only one answer. Oppenheimer’s team must go ahead with their calculations. Unless they came up with a firm and reliable conclusion that our atomic bombs could not explode the air or the sea, these bombs must never be made.”209

  Facing, indeed, possibilities that no human being had ever confronted before, one would like to think that this was an inevitable judgment. It turns out, that was far from being so. In fact, Compton didn’t entirely hold to it himself.

  The Manhattan Project did continue, at full blast (so to speak), but not because further calculations and partial tests proved beyond doubt that there was no possibility of what became known as “atmospheric ignition.” Some scientists may have come to trust Bethe’s calculations, or really, his initial gut feeling, that this result was “impossible.” But many others did not.

  As months went by, with the work having resumed on a crash basis, no one, including Bethe, was able to convince most others that the ultimate catastrophe was “not possible”: which Compton, in charge of the project, had laid down, seemingly reasonably, as the definite condition for pursuing the work. Very unlikely, yes. But not impossible.

  Just how unlikely? Was the risk, in some sense, “negligible”? How low was it? And just how low would the risk have to be—of killing everybody, every living thing?—to be acceptable? In a later interview with the novelist Pearl S. Buck, Compton recounted the story above (in almost identical words) and then added, according to Buck, that while the work went on for the next three months,

  scientists discussed the dangers of fusion210 but without agreement. Again Compton took the lead in the final decision. If, after calculation, he said, it were proved that the chances were more than approximately three in a million that the earth would be vaporized by the atomic explosion, he would not proceed with the project. Calculation proved the figures slightly less—and the project continued.

  Say what? How does one arrive at a precise upper limit of “three in a million”? What is it derived from, and what does it mean? In this case, it meant: “Small, very small. We don’t know exactly.” Most of the senior theorists did believe the chance was very small, but not zero. When Compton had been assured that the risk was not more than the “three in a million” chance (which he had more or less pulled out of the air as the upper limit to be accepted for continuing the work), he decided, contrary to his initial reaction, that although it was not “no chance,” it was low enough to resume research. All the others went along with that. As Peter Goodchild puts it, “Once Bethe’s calculations had relegated atmospheric ignition211 to a remote possibility—at least for the time being—the group returned to the issue at hand [designing a fission bomb].”

  “For the time being”—meaning, awaiting further calculations, hopefully that would prove the possibility was zero (as Compton had initially demanded of Oppenheimer), prior to conducting an actual explosion. But calculations before the test never did demonstrate that.

  Nearly every account to be found of the problem of atmospheric ignition describes it, incorrectly, as having been proven to be a strict non-problem—an impossibility—soon after it first arose in the initial discussion of the theoretical group, or at any rate well before a device was actually detonated.

  I know this to be untrue because I heard that from the lips of the official historian of the Manhattan Project, David Hawkins, who had been hired to write an ongoing, highly classified account of the process from its earliest days. When I questioned him at the University of Colorado in 1982, he elucidated an often-quoted statement from his own eventually declassified 1945 history: “The impossibility of igniting the atmosphere212 was thus assumed by science and common sense.” “Impossibility” in that passage, he explained to me, “didn’t mean no possibility.” It meant “for practical purposes” a “negligible” chance: “enough assurance to proceed with the work.”

  He told me that he had “done more interviews with the participants on this particular subject, both before and after the Trinity test, than on any other subject” in his research. What the problem did become, he said, was a nonsubject for further discussion by the project’s leaders with the other researchers. “They had to keep batting it down. Younger researchers kept rediscovering the possibility, from start to finish of the project.” When they brought it up privately to a senior theorist, with considerable anxiety, they would be told, “We’ve looked into that; it’s been taken care of; don’t worry about it.”

  Prior to the detonations at the Trinity site, Hiroshima, or Nagasaki, Hawkins told me firmly, they never confirmed b
y theoretical calculations that the chance of atmospheric ignition from any one of these was zero. Even if they had, the experimentalists among them would have recognized that the calculations could have been in error or could have failed to take something into account. That was very much in Enrico Fermi’s mind, and even Edward Teller’s, on the eve of the first test.

  Most accounts of the Trinity test on the early morning of July 17, 1945, recount that Fermi offered to accept bets the night before as to whether atmospheric ignition would occur. He said, “I feel I am now in a position to make book [that is, to accept bets at fixed odds] on two contingencies: 1) that the explosion will burn New Mexico; 2) that it will ignite the whole world.”

  Too bad that the actual odds Fermi offered that night on these events are lost to history. Whether anyone placed money with Fermi and what odds he did offer seem never to have been reported. There are strong hints that his odds for total atmospheric ignition were much higher than three in a million. He would hardly have offered to “make book” on the basis of odds like that.

  Accounts agree that when General Groves,213 the military officer in charge of the Manhattan Project, heard about this offer, he was angry; he feared it would upset the enlisted men. He had himself prepared a draft news release in case the explosion was larger than expected and destroyed Oppenheimer and the other observers. It mentioned simply an “accidental explosion.” He was disconcerted that Fermi’s reported bets would imply to some that he might need a different press bulletin: “We’ve lost New Mexico.” (If Fermi had won the second bet, about the end of life on earth, no bulletin would be necessary.) But on second thought, Groves concluded that Fermi was joking.