Реферат: Little Boy Essay Research Paper Little BoyOn
Little Boy Essay, Research Paper
On the morning of August 6, 1945, a B-29 bomber named Enola Gay flew over the industrial city of Hiroshima, Japan and dropped the first atomic bomb ever used in war. The city went up in flames caused by the immense power equal to about 20,000 tons of TNT. The project was a success. Hundreds of thousands died and still more were wounded. This was the final triumph that finally brought Japan to surrender. The effects of the bomb are still being seen but there is no doubt that the atomic bomb project was the greatest scientific feat of the 20th century. There was an unprecedented assemblage of civilian, military, and scientific, minds at work. Their pertinacious, intense, and theological ideas helped shape a new era. Unknowingly they also help shape what could have been the end of earth its self. This dim future was best described by Albert Einstein, the man responsible for starting the atomic bomb project in the US, “I know not with what weapons World War 3 will be fought with but I do know that world war 4 will be fought with sticks and stones.” As one can see begin serious controversies concerning its sheer power and destruction began as soon as the first bomb was used on Hiroshima.
The Manhattan Project was the code name for the US effort during World War II to produce the atomic bomb. It was appropriately named for the Manhattan Engineer District of the US Army Corps of Engineers, because much of the early research was done in New York City (Badash). Sparked by refugee physicists in the United States, the program was slowly organized after German scientists discovered nuclear fission in 1938. Many US scientists expressed the fear that Hitler would attempt to build a fission bomb. In theory this “fission bomb” would be more destructive than all the explosives they had in their hands (Rhode 340). Frustrated with the idea that Germany might produce an atomic bomb first, Leo Szilard and Eugene Wigner asked Albert Einstein, a famous scientist during that time, to use his influence and write a letter to president FDR. The letter pleaded for support to further research the power of nuclear fission and warned the president of the unfathomable destruction Hitler could cause (Badash). His letters were a success, and President Roosevelt established “The Fission Bomb Project” (Brown & Macdonald 140).
Physicists from 1939 onward, conducted much research to find answers to such questions as “how many neutrons were emitted in each fission?” “Which elements would not capture the neutrons but would moderate or reduce their velocity?” and “which element achieved the most powerful fission?” After their research the scientists found the Uranium was the most effective for their project. The next question was which isotope of the fissured more effectively, the lighter and scarcer isotope of uranium (U-235) or the common isotope (U-238). They also learned that each fission releases a few neutrons. A chain reaction, therefore, was theoretically possible, if not too many neutrons escaped from the mass or were captured by impurities. To create this chain reaction and turn it into a usable weapon was the ultimate goal of the Manhattan Project.
In 1942 General Leslie Groves was chosen to succeed Vannevar Bush as the head of “the Fission Bomb Project” During this changeover the project was renamed in army fashion to a code name, “the Manhattan Project”. Groves immediately purchased a site at Oak Ridge, Tennessee, for facilities to separate the necessary uranium-235 from the much more common uranium-238. Uranium 235 was an optimal choice for the bomb because of its unusually unstable composition. Thus, the race to separate the two began. During that time, the work to perfect the firing mechanism and structure of the bomb was also swiftly underway.
General Groves’ initial task had been to select a scientific director for the bomb project. His first two choices, Ernest O. Lawrence and Arthur H. Compton, were not available. Groves had some doubts regarding the next best candidate, J. Robert Oppenheimer (Brown & Macdonald 42). Finally, Groves gambled on Oppenheimer, a theoretical mathematician, as director of the weapons laboratory. For Oppenheimer’s fist task he built a factory to produce the gun-firing mechanism for the bomb. The location of the factory was on an isolated mesa at Los Alamos, New Mexico.
After much difficulty, an absorbent barrier suitable for separating isotopes of uranium was developed and installed in the Oak Ridge gaseous diffusion plant. Since there was no known substance to separate the isotopes at the time, scientists invented a new material that is still in use today, Teflon. Finally, in 1945, the pure uranium-235 was shipped to Los Alamos, where it was fashioned into a gun-type weapon. In a barrel, one piece of uranium was fired at another, together forming a supercritical, explosive mass. (Badash) To achieve chain-reaction fission, a certain amount of fissionable material, called critical mass, is necessary. The fissionable material used in the Hiroshima model was uranium-235. For Nagasaki and Alamogordo, plutonium-239. In the bomb, the uranium was divided into two parts, both of which were below critical mass. The bomb was designed so that one part would be slammed into the other by an explosive device to achieve critical mass instantaneously (Badash). When critical mass is achieved, continuous fission (a chain reaction) takes place in an extremely short period of time, and far more energy is released than in the case of a gunpowder explosion (Badash). On December 2, 1942, the first self-sustaining chain reaction took place; overseen by Enrico Fermi a refugee Italian physicist, in the University of Chicago squash fields (Rhodes 283).
Another type of atomic bomb was also constructed using the synthetic element plutonium. Fermi built a reactor at Chicago in late 1942, nicknamed the “Chicago Pile”. The prototype of five production reactors erected at Hanford, Washington. These reactors manufactured plutonium by bombarding uranium-238 with neutrons causing the uranium to decay to neptunium and finally decay to plutonium. At Los Alamos the plutonium was surrounded with high explosives to compress it into a super dense, super critical mass far faster than could be done in Oppenheimer’s model. The result was tested at Alamogordo, New Mexico, on July 16, 1945, and was the first explosion of an atomic bomb code-named Trinity (Beyer 55).
However, all was not that easy coming up to this milestone point. Security restrictions bound both workers and townspeople to absolute silence. Everybody had the same address where all mail was censored (Rhodes 124). Everybody was restricted to a 200-mile radius, and residents of Los Alamos were prohibited from telling friends and relatives where they lived. Names were not allowed to be mentioned outside of the laboratory. Everybody was a “sir” or “mister”(Grolier). Sadly, there were serious issues of security, due to a failure to lock the facilities properly (Rhodes 345). The one serious incident was the hiring of Klaus Fuchs. He was later found, and convicted, of obtaining secret documents and sending them to the Soviet Union. A competent and hardworking scientist himself, Fuchs enabled the Soviet Union to create their own atomic bomb (Beyer 45).
Decisions to drop the atomic bomb went through several personalities, yet ultimately rested upon the newly appointed president Truman. The man, whose decisions created the Manhattan Project, never lived to see the results of his labor. FDR died on April 12, three months before the first successful Trinity test (Beyer 56). The responsibilities were soon placed upon Truman. Truman knew nothing about the bomb and its effects yet hastily decided that the bomb be used on Japan. Considering Germany was no longer a target with the war in Europe over, Szilard, made a petition to offer the opinion that the bomb should be used only if Japan refused to surrender, even after being informed of the bomb’s destructive capabilities (Beyer 65). Nevertheless, the decision was made that the bombs would be used until Japan surrendered.
The Hiroshima model, or Oppenheimer’s bomb, is known as a gun-barrel-type atomic bomb. Due to its long and narrow shape, the Hiroshima model was called “Thin Man” at first, but during the manufacturing process the original plans were modified, shortening the length and giving rise to the name “Little Boy” (Beyer 48). The energy released from the Hiroshima A-bomb was originally thought to be equivalent to the destructive power of 20,000 tons of TNT. Later estimates, however, put the energy equivalent to approximately 15,000 tons of TNT, based on damage done to buildings and research on the bomb’s composition. Despite the release of such enormous energy, it is believed that less than one kilogram of the 10 to 30 kilograms of uranium-235 housed in the bomb achieved fission.
The fissionable material used in the Nagasaki bomb, or Fermi’s bomb, was plutonium-239. The plutonium-239 was divided into below-critical-mass units and packed into a spherical case. At the time of detonation, the units were compressed to the center with a gunpowder explosion to achieve fission. The Nagasaki model is known as an implosion-type atomic bomb. Compared to “Little boy”, the one used in Nagasaki was larger in diameter and round so it was called “Fat Man.” Only slightly more than one kilogram of the plutonium 239 is thought to have achieved fusion, but the energy released is estimated to be equivalent to the destructive power of about 20,000 tons of TNT (Grolier).
While the first atomic bomb was a roaring success, it raised many ethical and controversial issues. Most of the people in the United States of America supported the use of the atomic bomb, even President Truman called it, “the greatest thing in history” (Beyer 75). Many people, including the scientists that developed the bomb, opposed the bombings and felt that it was immoral to kill that many innocent people just to get an influence in the war. This feeling can be seen in Oppenheimer’s quote after the use of the first bomb, “…now I am become Death [Shiva], the destroyer of worlds…”
Controversy still exists on the reasons for destroying Hiroshima and Nagasaki. Killing over 100,000 people and wounding about the same did not win the war in the pacific. It at best hastened the Japanese acceptance of defeat (Grolier). Proponents claim the invasion that otherwise would have been required would have required an untold carnage and loose of American life. Those opposed argued in retrospect, the bomb might have been the first act of the cold war.
The Manhattan Project was one of the most important parts of American History. It was the first effort to create an atomic bomb that helped end the war in the Pacific. It also helped understand the sheer strength and power of what a small element can do. All of our lives have changed through the development and use of the atomic bomb. The cold wars, nuclear restrictions, nuclear energy, are all results of the first nuclear breakthrough. As well as a whole new line of plastics and more efficient gun mechanisms. However, the controversial issues will still rage on. Nuclear testing, nuclear power, and nuclear waste are still being debated for over 50 years, and the United States, the only country to actually use the bomb, is the leader. Perhaps Cicero had it right when he said, “No beast is more savage than man, when possessed with power answerable to his rage.