As luck would have it, Hahn and Strassman were opponents of the regime. Hahn wrote to the Austrian chemist Lise Meitner, who had worked with him in Berlin until she fled to Sweden after the Nazis occupied Vienna in Meitner wrote back explaining that the uranium nucleus was splitting into two roughly equal parts. The next piece of the puzzle came when Italian physicist Enrico Fermi, who had fled Fascism and was working at Columbia University in New York, discovered that uranium fission released the secondary neutrons that were needed to make the chain reaction happen.
Szilard soon joined Fermi in New York. Together they calculated that a kilogram of uranium would generate about as much energy as 20, tonnes of TNT. Szilard already saw the prospect of nuclear war. Others did have doubts, however. In the Danish physicist Niels Bohr — who was actively helping German scientists escape via Copenhagen — poured cold water on the idea. While some scientists feared a dud, others feared the end of the world. At a. The bomb was dropped. There was a forceful flash, a wave of heat, a stupendous shock wave, and a mushroom cloud extending 40, feet into the atmosphere.
The tower from which the bomb was dropped disintegrated, and thousands of yards of surrounding desert sand was turned into a brilliant jade green radioactive glass.
The bright light from the Trinity test stood out in the minds of everyone within hundreds of miles of the site that morning. Residents in faraway neighborhoods said the sun rose twice that day.
A blind girl miles from the site said she saw the flash. The men who created the bomb were astonished. Physicist Isidor Rabi expressed worry that mankind had become a threat to upset the equilibrium of nature. The test brought to Oppenheimer's mind a line from the Bhagavad Gita: "Now I am become death, the destroyer of worlds. The unease among many witnesses led some to sign petitions arguing that this terrible thing they had created could not be let loose in the world. Their protests were ignored.
Germany surrendered on May 8, , two months before the Trinity test. Japan refused to surrender, despite threats from Truman that terror would fall from the sky. The war had lasted six years and involved most of the globe, resulting in the deaths of 61 million people and the displacement of countless others. The last thing the U. Robert Lewis, co-pilot of the B bomber, wrote in his journal moments later, "My God, what have we done? At that morning the bomb was dropped, and by over 66, people near ground zero were dead.
Some 69, more were injured, most burned or suffering from radiation sickness, from which many would later die. This single atomic bomb produced absolute devastation.
It left a "total vaporization" zone of one-half mile in diameter. The "total destruction" area extended to one mile, while the impact of a "severe blast" was felt for two miles. Anything flammable within two and a half miles was burned, and blazing infernos were seen up to three miles away.
The bomb's target was the city of Nagasaki, Japan. The following year, Italian physicist Enrico Fermi unknowingly split neutrons within uranium while conducting his own experiments. On the heels of these developments, Austrian-Swedish physicist Lise Meitner, working with German chemist Otto Hahn, was among the first to achieve the successful fission of uranium. However, the antisemitism of the Nazi party forced Meitner, who was Jewish, to flee and settle in Sweden.
While in Sweden, Meitner identified and named the process of nuclear fission. While Hahn chose to remain in Germany and continued to develop his research throughout World War II, scientists across Europe steadily fled.
Szilard, a Jewish man, migrated to the United States in to avoid persecution. Fermi and his wife, Laura Capon, also left Europe at the end of to escape growing Fascism in Italy. Capon, who was also Jewish, traveled with Fermi to New York City where both applied for permanent residency. Although formed in , the Advisory Committee on Uranium moved slowly at first. With the United States formally at war, the question of uranium development and the potential construction of an atomic bomb gained renewed interest.
This interest rose even higher as a report issued by British scientists in March confirmed the possibility of building a uranium-based bomb, giving American scientists the validation they sought. In spite of this enthusiasm, the limitation of resources quickly became evident and prompted committee leaders to turn to the military for help.
As the United States began its island-hopping campaign in the Pacific, the Army Corps of Engineers took over the effort to produce atomic weaponry on the Home Front.
The following month, on September 17, Colonel Leslie R. Groves was appointed to head the project and received a promotion to Brigadier General. Within two days of his appointment, Groves made quick decisions to move the project forward, selecting three primary sites for the manufacture of an atomic bomb.
Groves first selected Oak Ridge, Tennessee, as the site for uranium enrichment. Also among the primary project sites was Los Alamos, New Mexico. This Los Alamos site would become the location for the construction of the atomic bombs.
The gaseous diffusion process employed a porous barrier through which uranium hexaflouride gas would be pumped; the lighter molecules of U would pass through more readily than the heavier ones of U and could be collected via a chemical process. Construction by the contractor experienced no unusual difficulties, but a nationwide shortage of copper for the massive magnets for the electromagnetic system had to be solved by using silver, which came from the U. Treasury Depository in huge quantities.
By October the system was ready for testing. However, it soon became apparent that the magnets were plagued by numerous electrical shorts, caused by faulty design and manufacture. All of the 48 magnets had to be rebuilt. Finally the system was ready for operation in January Thousands of diffusion tanks for the gaseous-diffusion process would be required. Selection of a suitable barrier material was a difficult problem, causing a dispute among adherents of competing approaches.
Groves finally decided to submit the matter to a British-American committee, who ratified a decision that he had already made to use a new but superior design that would further delay production. The date of Groves' decision was in early January In early Oak Ridge began shipping weapon-grade U to Los Alamos, where weapon development was taking place.
In early Groves had selected Hanford, Washington, as the site for plutonium production. The selection of Hanford over Oak Ridge was based on the former's remote location, which militated against disastrous results if a nuclear accident occurred. Major design, recruiting, and construction problems existed, but the principal buildings were ready for installation of the first nuclear pile by February Plutonium production in quantity began in December The next major problem, which surfaced in late , was the establishment of a laboratory for work on bomb design.
General Groves favored Robert Oppenheimer as the director, although Army counterintelligence objected because of Oppenheimer's former friends who had been Communist Party members. Groves was able to convince Vannevar Bush, the head of the Office of Scientific Research and Development, that no one else could be a better choice.
The site was on the grounds of a boys' school located on a rugged mesa thirty-five miles northwest of Santa Fe. Manning and construction started in early The remoteness of the site made recruiting of qualified personnel difficult, but Oppenheimer was able to appeal to most candidates' patriotism.
There were two possible approaches to bomb design. The first was to achieve a critical mass and the resulting nuclear explosion by very rapidly joining two sub-critical halves and initiating a neutron source. This approach was called the "gun type" since the system used a tube in which the two halves were fired toward each other. The other, newer approach used a ball called core of fissionable material surrounded by a number of lenses of explosive which when detonated squeezed the ball into a critical mass.
The neutron initiator was located in the center of the core. This approach was called the implosion method. The gun-type was considered the more reliable; the implosion method required simultaneous detonation of the lenses and was relatively risky. In early the Army Air Forces started its program to develop a delivery capability using the B aircraft.
The B was the logical choice in view of its long range, superior high-altitude performance, and ability to carry an atomic bomb that was expected to weigh to 10, pounds. In August seventeen Bs entered a modification program at the Glenn L. Martin plant in Omaha, Nebraska, to apply the lessons learned at Muroc.
That month the decision was made to train a special group to deliver the first atomic bombs; and a squadron then based at Fairmont, Nebraska, in training for assignment to Europe, was selected to form the nucleus of the new organization, which was designated the th Composite Group.
Tibbetts to command the th. Tibbets was highly qualified for the position. An intensive training program for the th took place, designed specifically to prepare the crews for a high altitude release of the bomb, including an escape maneuver that would avoid the shock wave that could damage or destroy the aircraft.
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