by P. D. Smith
At the end of 1939, Otto Frisch was working at Birmingham University. He dreaded the coming hostilities. ‘We all imagined scenes out of H. G. Wells’s The Shape of Things to Come: a fleet of aeroplanes dropping thousands of bombs, buildings toppling, millions fleeing…’1 Wells, the idealistic visionary of science, was appalled by the role that scientists were going to play in this destruction and by the idea that ‘thousands of clear and active minds, each indisputably sane, could, in an atmosphere obsessed by plausible false assumptions about patriotic duty and honour, cooperate to produce a combined result fantastically futile and cruel.’
Readers of H. G. Wells’s fiction were familiar with mad scientists – Griffin or Moreau, for example – as well as those who hoped to improve the world, men like Holsten and Karenin. But who, asked Wells in The Shape of Things to Come, were these faceless scientists working in secret laboratories to develop weapons of mass destruction?
The people engaged in this business were, on the whole, exceptionally grave, industrious and alert-minded. Could they revisit the world to-day individually we should probably find them all respectable, companionable, intelligible persons. Yet in the aggregate they amounted to an organization of dangerous lunatics. They inflicted dreadful deaths, hideous sufferings or tormented lives upon, it is estimated, about a million of their fellow creatures.2
Building the atomic bombs that devastated two Japanese cities in 1945 was the result of an enormous industrial, military and scientific effort. It could perhaps be argued that, like General Ishii’s Unit 731, it was an ‘organization of dangerous lunatics’. But the scale of the enterprise and the speed with which it was completed remains breathtaking, even today. Almost certainly America was the only country that could have achieved this while fighting a world war. Fear marshalled the talents of the greatest scientists and engineers in the world, and, overseen by the brusque and bullying General Groves, they translated pure science into military reality.
Niels Bohr had told colleagues that to separate uranium–235 from natural uranium on an industrial scale, a country would have to transform itself into a vast factory. When Bohr eventually arrived at Los Alamos at the end of 1943, Edward Teller anticipated a satisfying moment of Schadenfreude. ‘I was prepared to say, “You see…” But before I could open my mouth, he said: “You see, I told you it couldn’t be done without turning the whole country into a factory. You have done just that.’ ”3
The Manhattan Project had four main sites. As well as the Met Lab at Chicago, there was Oak Ridge, near Clinton, east Tennessee, where uranium– 235 was separated from uranium-238 ; and Hanford, near the town of Richland, Washington, the site of the reactors that created plutonium, and the facilities to separate this from the uranium fuel. The fourth, top-secret site in the superweapon project was Los Alamos, the laboratory where the bombs were designed and made.
The atomic bombs were known by the innocuous code name ‘the gadget’. It was a name that could have come straight from the pages of a science fiction pulp, or one of Hugo Gernsback’s technology magazines. Indeed, with an average age of 25, many of the scientists and technicians on the Manhattan Project had been weaned on a diet of sci-fi and gadget pulps. The atomic bomb owed its existence to this technophile culture, with its saviour scientists and superweapons, as much as it did to the individual genius of its scientists and engineers.
Indeed, the Manhattan Project scientists sometimes described their work as being straight out of a science fiction story. The Hungarian mathematician Peter Lax, the nephew of Szilard’s friend Albert Korodi, had arrived in America in 1941, aged just 15. While studying at New York University in 1945, he received his call-up papers for the army. But the front line for Lax turned out to be the Neutron Department at Los Alamos, working on the development of the first plutonium bomb. ‘It was like a piece of science fiction,’ he said, ‘working with an element which was not to be found in the Periodic Table.’4
The Manhattan Project employed up to 130,000 people at any one time. Many thousands more were involved indirectly, working for big corporations such as Union Carbide and Du Pont, a company which had also produced chemical weapons during World War I. By the end of the war there were 6,000 people working on the ‘magic mesa’ at Los Alamos. The majority of the scientists at Los Alamos, or the Hill as they called it, found the work stimulating and indeed great fun. Hans Bethe said that for many of the scientists, the 27 months they spent there building superweapons was the best time of their lives.
Laura Fermi arrived at Los Alamos in August 1944 with her two young children, Nella and Giulio. By this time, Los Alamos was a thriving community:
Into that city went scientists from all parts of the United States and England, to disappear from the world. For two and a half years the city was not marked on the maps, had no official status, was not part of New Mexico, its residents could not vote. It did not exist. That city was Los Alamos to those living there, Site Y to the few outsiders who knew about its existence, Post Office Box 1663 to correspondents and friends of the inhabitants.5
The Fermis were assigned Apartment D in building T-186. Below them, in Apartment B, lived Rudolf and Genia Peierls. As Teller said, everyone on the Hill became ‘one big, happy family’.6
Enrico Fermi had worked first at Met Lab, then at Hanford, where Du Pont was constructing the huge reactors for plutonium production. In common with the other top atomic scientists, he had a personal bodyguard. But such was the secrecy surrounding the project that he was unable to tell Laura what he was working on. One scientist announced to his wife the news that they were going to New Mexico with the words: ‘I can tell you nothing about it. We’re going away that’s all.’7 Like most of the other spouses, Laura did not know the lethal nature of her husband’s work until the news broke about the destruction of Hiroshima.
The Manhattan Project began and ended with two crucial scientific experiments: one in 1942 when the Chicago atomic pile went critical, and the second in 1945 when the first atomic bomb was detonated. The Trinity test, as Robert Oppenheimer rather cryptically named it, demonstrated beyond doubt the terrible explosive power of the new element, plutonium.
In April 1943 Oppenheimer convened an inaugural conference at Los Alamos for the key bomb scientists. Its purpose was to bring everyone up to speed on the current state of knowledge about the bomb and to establish what problems remained to be solved. For some of them, the opening lecture by Robert Serber was a revelation. The policy of compartmentalization – something Szilard constantly criticized – meant that their knowledge had been restricted to the specific area in which they were working. Now the true scale of the endeavour became clear. ‘The object of the project,’ said Serber, ‘is to produce a practical military weapon in the form of a bomb in which the energy is released by a fast neutron chain reaction in one or more of the materials known to show nuclear fission.’8
Serber told them in 1943 that they now believed the critical mass for uranium–235 was 33 lb, in the form of a core about the size of a cantaloupe melon. For plutonium it was just 12 lb, or about the size of a tennis ball. Both would need to be enclosed in a heavy tamper, or shell, of uranium. The uranium would reflect the neutrons back into the heart of the bomb, increasing the number of potential fission reactions and thus the explosive yield of the bomb. According to Bethe, ‘relatively little nuclear physics’ was needed at Los Alamos.9 They were there to engineer a military weapon. But problems remained. Devising a way of rapidly bringing together a critical mass so as to avoid a premature and thus inefficient detonation caused by stray neutrons was one major hurdle.
Eventually two different bomb designs were developed, one for uranium–235 and the other for plutonium. The former used a gun barrel to fire a plug consisting of tamper and core into the subcritical mass, thereby bringing it to explosive criticality. For plutonium this method would not work. The critical mass had to be brought together much more rapidly in order to avoid predetonation. As an alternative, Seth Neddermeyer came up with the
ingenious yet technically difficult idea of using chemical explosives to create an implosion, instantly compressing a sphere of plutonium into a critical mass.
John von Neumann was called in to work on this promising solution, as well as the complex hydrodynamics of explosions. The brilliant Princeton mathematician was already working for the military designing the specially shaped charges used in the armour-piercing bazooka. In October 1943, together with Teller, he applied his knowledge on the dynamics of shock waves to the problem of how to use conventional explosives to implode the sphere of plutonium. The plan was for the explosives to squeeze the plutonium at pressures greater than those at the centre of the earth, instantly compressing the core into criticality and setting off the nuclear explosion. It was a revolutionary design, but because of its complexity a full-scale test was needed. No one wanted to drop an atomic bomb that did not explode, thus delivering years of research into the hands of an enemy. By contrast, the scientists were now so certain that the uranium bomb would explode, that it was never tested – at least not until it was dropped on the city of Hiroshima.
There had never been a physics experiment quite like Trinity. The bomb was winched up a hundred-foot wooden tower at the location that would become known as the original Ground Zero. A series of reinforced concrete bunkers had been built to house cameras and scientific instruments, from seismographs to ionization chambers, which would record every aspect of the explosion. The data would travel down some five hundred miles of heavy cabling. The gadget consisted of a five-foot sphere containing shaped charges of high explosives around a core of plutonium no bigger than a tennis ball. The plutonium had been created in reactors like the one Fermi and Szilard had built in Chicago in 1942. As the scientists gingerly inserted the plutonium into the bomb casing, the new element felt warm to the touch, as if it were alive.
Physicist Norris E. Bradbury sits next to ‘the gadget’, the code name for the atomic bomb exploded in the Trinity test, July 1945. Bradbury was in charge of assembling the high-explosive charges (known as lenses) which surrounded the plutonium core of the superweapon.
The initial date of the test had been set for 4 July, but it was delayed until the 16th. Truman responded by postponing the Potsdam Conference with Churchill and Stalin. More than just scientific reputations depended on the outcome of this scientific experiment. The fate of nations was at stake.
The piece of arid land where the test was conducted had been named the Jornada del Muerto by the first Spanish explorers who passed through the area. The Journey of the Dead was a fitting name for a landscape that was to witness the detonation of the most destructive device yet constructed. In the early hours of 16 July, well before sunrise, staff were bussed in from Los Alamos. The sleepy audience gathered in the dark, twenty miles north of Ground Zero, on Compañia Hill. They included Hans Bethe, Edward Teller and the young physicist Richard Feynman. James Chadwick had come along in order to see just how powerful the neutron he had discovered thirteen years ago really was.
At Base Camp, about ten miles from Ground Zero, Enrico Fermi resurrected the nightmare scenario that had so frightened Compton three years earlier. He annoyed both his colleagues and General Groves by offering to take wagers on whether the bomb would ignite the atmosphere ‘and, if so, whether it would merely destroy New Mexico or destroy the world’.10 It was a theoretical possibility that haunted many people that morning. Meanwhile, Robert Oppenheimer waited nervously in the concrete control bunker nearly six miles south of Ground Zero, the closest observation point to the bomb.
At the last minute, the test had to be delayed again because of a violent thunderstorm. A new detonation time was set for 5.30 a.m. As lightning flickered in the sky, the scientists and the generals became increasingly edgy. Up on Compñia ia Hill was William Laurence, the only journalist allowed to witness ‘the first fire ever made on earth that did not have its origin in the sun’.11 He recalled how they were told to lie down, facing away from the blast with their faces turned to the ground. Dark welder’s glass was handed out to protect their eyes from the blinding flash. Edward Teller advised him to rub suntan lotion on his exposed skin as protection against the dangerous UV radiation. ‘It was an eerie sight,’ said Laurence, ‘to see a number of our highest-ranking scientists seriously rubbing sunburn lotion on their faces and hands in the pitch blackness of the night, 20 miles away from the expected flash.’12
At 5.25 a.m. a green flare was fired from Oppenheimer’s control bunker and a siren wailed into the night. At Base Camp the scientists and soldiers lay down in shallow trenches that looked like graves. One minute before detonation, another warning flare was fired and again a siren sounded, echoing across the desert. These warnings were repeated at zero minus ten seconds. For Isidor Rabi, waiting anxiously at Base Camp, those final ten seconds lying in the darkness lasted an eternity. Then suddenly, said Rabi,
there was an enormous flash of light, the brightest light I have ever seen or that I think anyone has ever seen. It blasted; it pounced; it bored its way right through you. It was a vision which was seen with more than the eye. It was seen to last forever. You would wish it would stop; altogether it lasted about two seconds. Finally it was over, diminishing, and we looked toward the place where the bomb had been; there was an enormous ball of fire which grew and grew and it rolled as it grew; it went up into the air, in yellow flashes and into scarlet and green. It looked menacing. It seemed to come toward one.
As Rabi stared at the fireball, mesmerized, he realized that ‘a new thing had just been born; a new control; a new understanding of man, which man had acquired over nature.’13
Alongside him at Base Camp was Fermi’s colleague Emilio Segrè. When he saw the ‘unbelievable brightness’ burning through the dark glass, for a sickening moment he too feared ‘the explosion might set fire to the atmosphere and thus finish the earth’.14 Philip Morrison, also at Base Camp, was astonished by the heat of the explosion on that cold, dark desert morning: ‘It was like opening a hot oven with the sun coming out like a sunrise.’15
Enrico Fermi felt the shock wave strike him forty seconds after the blast. True experimentalist that he was, Fermi had prepared a test to estimate the strength of the blast. He dropped small pieces of paper from a height of six feet. They travelled about eight feet in the blast wave. Using his trusty slide-rule, he calculated the yield at 10,000 tons of TNT. Later his wife joked that ‘he was so profoundly and totally absorbed in his bits of paper that he was not aware of the tremendous noise’.16
On Compañia ia Hill, moments before the explosion, Laurence could see the ‘first faint signs of dawn’ in the east:
And just at that instant there rose from the bowels of the earth a light not of this world, the light of many suns in one. It was a sunrise such as the world had never seen, a great green super-sun climbing in a fraction of a second to a height of more than 8,000 feet, rising ever higher until it touched the clouds, lighting up earth and sky all around with a dazzling luminosity.
It was, Laurence thought, like ‘an elemental force freed from its bonds after being chained for billions of years.’ He also described the ‘great cloud’ that formed, ‘a giant column, which soon took the shape of a supramundane mushroom’.17
The Trinity atomic test. At 5.30 a.m. on 16 July 1945, just before dawn, an artificial sun rises from the desert of the Jornada del Muerto, New Mexico.
For a ‘very short but extremely long time’, the landscape around Laurence and the others on the hill was completely and eerily silent as they gazed in awe at the expanding fireball. It was like ‘a vibrant volcano spouting fire to the sky’. Thirty years before, Wells too had imagined an atomic explosion as being like a volcano. Then, about a hundred seconds after the flash, came the ‘first cry of a newborn world’. ‘The thunder reverberated all through the desert, bounced back and forth from the Sierra Oscuro, echo upon echo. The ground trembled under our feet as in an earthquake.’ Prometheus, as Laurence said, ‘had broken his bonds and brought a new fire
down to the earth’.18
The chemist George B. Kistiakowsky had fought with the White Russian Army before he came to America. The explosives expert had made the gadget’s specially shaped charges (‘lenses’) which focused the force of the implosion onto the plutonium core. Unlike the physicists, he had a fairly low expectation of the power of the bomb. He left the safety of the concrete control bunker seconds before detonation to watch the explosion. Kistiakowsky was knocked off his feet by the blast at a distance of 10,000 yards. As he said afterwards, the explosion at Trinity was ‘the nearest thing to doomsday that one could possibly imagine. I am sure that at the end of the world – in the last millisecond of the earth’s existence – the last man will see what we have just seen!’19
Brigadier General Thomas F. Farrell, Groves’s deputy, was also in the control bunker. In his official report to the War Department of what he saw that July morning, the experienced soldier struggled to find words to express the enormity of the moment:
The effects could well be called unprecedented, magnificent, beautiful, stupendous and terrifying. No man-made phenomenon of such tremendous power had ever occurred before. The lighting effects beggared description. The whole country was lighted by a searching light with the intensity many times that of the midday sun. It was golden, purple, violet, grey and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined. It was that beauty the great poets dream about but describe most poorly and inadequately. Thirty seconds after the explosion, came, first, the air blast, pressing hard against the people and things; to be followed almost immediately by the strong, sustained, awesome roar which warned of doomsday and made us feel that we puny things were blasphemous to dare tamper with the forces heretofore reserved to the Almighty.20