At exactly 5:29 and 45 seconds on the morning of July 16, 1945, in Alamogordo, New Mexico, an immense fireball “at first as bright as the sun” suddenly rose from the desert floor. Moments later the blast wave and “a loud cracking noise” echoed in the surrounding mountains.
Small groups of nearby scientists and military officers felt a sense of awe, followed by relief, as the detonation validated the work they had been doing in secret laboratories across the country as part of an effort to end the Second War. World.
The event was the Trinity test, the first explosion in the history of an atomic bomb. That day, the era of nuclear war was launched.
Just over three weeks later, that fact would become known worldwide through the Hiroshima atomic bombing on August 6, followed by the Nagasaki bombing on August 9.
Now we are all motherfuckers.
Kenneth T. Bainbridge, Manhattan Project
Trinity’s 75th anniversary is worth celebrating, if not celebrated on Thursday as a scientific achievement and as a sign of the challenge mankind has since faced to manage its own capacity for self-destruction.
We can relive the moment thanks to the memories of many of those assigned to the Manhattan Project who worked to bring Trinity and who witnessed the event first hand. Many of those oral histories have been compiled by the Bulletin of the Atomic Scientists and extracted in a striking and stimulating article on its website.
In fact, the article doesn’t include the memories of the chief scientist of the Manhattan Project, Ernest Lawrence of the University of California at Berkeley, but a copy of them came into my possession during the investigation of my 2015 Lawrence biography, “Big Science” . (The quotes in the first paragraph above are from his documents.)
To start at the end and work backwards, if the test team’s immediate reaction was a relief that their work had paid off, it was very quickly followed by a grim introspection about what they had created.
Kenneth T. Bainbridge, who was the immediate supervisor at the test site, stood up after the blast wave had passed and congratulated J. Robert Oppenheimer, whose team of engineers and physicists at Los Alamos had designed what they called the device”. “
He said to Oppenheimer: “Now we are all sons of bitches.”
Oppenheimer recalled that a phrase from the Sanskrit Bhagavad Gita, which he had studied when he was young, jumped into his mind: “Now I am becoming death, destroyer of worlds.” But first he quoted the phrase many years later; no one on the scene heard him refer to that. (In any case, according to some accounts, this is a mistranslation of “Now I have become hour, destroyer of worlds “, perhaps a more subtle and even more sinister thought).
Lawrence, who had been a close friend of Oppenheimer but then broke up bitterly with him, recalled that “the explosion produced a kind of solemnity in everyone’s behavior immediately afterwards … a silent murmur bordering on reverence.” Still, “they shared the feeling that this day we have crossed a great milestone in human progress.”
The road that led to Trinity had started about three years earlier with the creation of the Manhattan Project as an allied effort to produce an atomic weapon. The project’s military commander, General Leslie Groves, had put Lawrence in charge of scientific development, and Lawrence had recommended his friend and Berkeley colleague, Oppenheimer, to run the secret laboratory to solve technical problems in weapon design. .
Designing the first bomb, which had enriched uranium 235 as the nucleus, was a relatively trivial challenge. The design was known as a “weapon”: a subcritical plug of U-235 was fired into a subcritical U-235 hollow cylinder. When the pieces came together, they created a supercritical mass of fissile explosive uranium.
The enriched uranium was produced at a plant Lawrence designed and built in Oak Ridge, Tenn. But its production was so slow and sparse that it only produced enough material for a single pump, not even a test. But the engineering of the bomb was so simple that it was deemed not to require testing, and the only uranium bomb was detonated over Hiroshima on August 6, 1945.
The preferred bomb material was Plutonium-239, which had been discovered and isolated at Berkeley by Glenn Seaborg. P-239 could be produced in quantity. The problem was that it was so fissile that a weapon design wouldn’t work: the material would detonate before the pieces came together, creating a mess.
The “gadget” before being hoisted to the top of the test tower.
(United States Department of Defense)
Most of the work at Los Alamos was devoted to creating a design for a plutonium pump. Finally, the laboratory decided on an implosion model. Plutonium would form in a hollow, subcritical sphere. To achieve detonation, an outer layer of charges shaped like pieces of watermelon rind would explode, forcing the sphere to compress into a solid, supercritical ball.
The design was so novel that no one could be sure it would work. Nor was anyone completely sure of the energy it would produce; There was even some conjecture that the explosion would be so powerful that it would set the atmosphere ablaze, a prospect that was discredited by painstaking physical calculations.
The final step in designing the pump was for a test, called Trinity.
Bainbridge chose the remote site about 200 miles south of Albuquerque, and oversaw the construction of a group of rudimentary shacks as the test site a few months in advance. “Scorpions and gila monsters abounded,” recalled physicist Emilio Segrè.
The team at the site worked under conditions of extreme secrecy and punitive pressure. There was nothing to do but work all day until the desert heat became unbearable, repair their cots and resume work in the cool of the morning.
Laura Fermi, whose husband Enrico was the most experienced physicist in Los Alamos, was surprised when he returned home after the test: “He looked shrunken and aged, made of old parchment, so completely dry and golden in the desert sun. Exhausted for the test.
Observers assembled for the test must have been the most distinguished group of scientists ever convened for what was essentially a laboratory experiment, including eight past and future Nobel laureates (not including Oppenheimer, widely regarded as the physicist brightest of his time). to win a Nobel).
In the center of the site was a 100-foot steel tower from which the “device” would be suspended. The nucleus arrived from Los Alamos through a guarded caravan on July 13 and was hoisted to the tower the following day.
The base camp, about 10 miles from the tower, was packed with scientists and luminaries. Most were sent to an observation post at Compania Hill, a rough 10-mile, three-hour drive. There, Lawrence encountered a group of colleagues, including a young Caltech physicist named Richard Feynman, who was playing on the publication’s radio.
Thunderstorms passed through the site. That night, Segrè recalled, “I was struck by an incredible noise whose nature completely escaped me. While the noise persisted … I went out with a flashlight and found hundreds of frogs in the act of making love in a large hole that had filled with water. “
The storms forced the test shot to be postponed from 4 to 5:30 am, and observers spent time making bets on his performance, covering his face with bronzer and fiddling with his goggles. At base camp, observers were instructed to lie face down in dug trenches to protect them from the blast, with their feet pointing toward the tower and covering their eyes with their hands.
“We were dealing with unknowns outside the realm of man’s experience,” Groves recalled, “and we just had to try to imagine everything that could happen.”
“Then came the last minute countdown,” recalled physicist Boyce McDaniel. “Finally, the bright flash of an ever-growing sphere was followed by the undulating flame of an orange ball rising above the plain.”
At the time of the detonation, Bainbridge “felt the heat at the nape of his neck, eerily warm. I was finally able to take off my glasses and watch the fireball rise rapidly. He was surrounded by a huge cloud of transparent purple air produced in part by the radiation from the bomb and its fission products. No one who has seen it could forget it, a dirty and amazing display. “
Val Fitch, a future Nobel laureate assigned to Trinity as a military technician, recalled, “Apparently no one had told the military police stationed at the bunker gate to control access, what to expect. He was absolutely pale and had an incredible expression of alarm when he left the bunker door to stand next to me and see the view. I simply said what I had in mind: “The war will soon end.”
J. Robert Oppenheimer (left) and the head of the Manhattan Project, General Leslie R. Groves, in the remains of the 100-foot tower that contained the test bomb at Trinity.
(US Department of Energy)
That was true, but the battle for nuclear weapons was not. President Truman received news of the successful test while meeting Winston Churchill and Josef Stalin in Potsdam, outside Berlin. He mentioned to Stalin that “we had a new weapon of unusual destructive force,” Truman recalled. “All he said was that he was glad to hear it and hoped we would make a ‘good use against the Japanese.'”
After the war, Oppenheimer led a campaign to bring nuclear technology under international control. It was an idea doomed to failure amid the postwar conflict between the West and the Soviets.
After Hiroshima and Nagasaki, American physicists were hailed as heroes. Over time, however, the gravity of her achievement began to sink. That was especially true after Truman agreed to launch a project to develop the hydrogen bomb, a truly unimaginable weapon of power.
The project divided the physical fraternity. Working on the Manhattan Project could be justified as part of the effort to defeat Hitler, and especially to keep an atomic bomb out of his hands by hitting him. (Actually, as the Allies discovered after the war, the much-feared Nazi nuclear weapons program never took off.)
The H-bomb was a different story. Promoted by Lawrence and Edward Teller, he was viewed by many of his former colleagues as fundamentally immoral. Too powerful to be deployed as a practical weapon in warfare, even according to Pentagon reasoning, “it becomes a weapon that is in effect almost one of genocide,” Fermi wrote in a public statement.
Oppenheimer’s firm opposition to the project led to his bitter rape with Lawrence, and even more sadly to the government’s campaign to revoke his security clearance amid all-fabricated indications that it was unfair to the US. against Oppenheimer darkened his later years, an undeserved end to a career that helped save civilization.
As Oppenheimer envisioned, the rampant development of astonishingly powerful weapons would poison international relations and oppress human destiny for an unlimited future. The path to the Trinity has been well examined. The path from Trinity is still being mapped. The 75 years we have traveled since then are only a beginning.
