On August second of the year 1939, Albert Einstein sent a letter, written by Leo Szilard, to President Franklin D. Roosevelt telling Roosevelt of the opportunity that nuclear power could be harnessed into a weapon, and also warning of the threat of Germany discovering how to make it first. Both this opportunity and this fear led to the development of the Manhattan project; a group of scientists dedicated to finding use for atomic power as a weapon. In the 1930's there were many interesting and intriguing discoveries on atomic power and fission. These discoveries excited some scientists, but most believed that nuclear power would never be able to be harnessed into use as a weapon. Later in that decade, Leo Szilard discovered that a chain reaction, called fusion, might be possible.
He went to the United States and asked for funding, but was laughed at and flatly rejected, several times. After petitioning through Albert Einstein, Szilard was finally granted the $100 to buy graphite, which was to be used to absorb the explosion from the chain reaction while testing. About a year later, under the leadership of Enrico Fermi at the metallurgical laboratory of the University of Chicago, scientists were successful in creating a chain reaction while not blowing up the campus. Soon after that, Roosevelt finally agreed to expand funding to the secret project later known as the Manhattan Project. The Jewish Physicists Szilard and Einstein originally started the idea of the Manhattan project, but there where many other Scientists that had a lot to do with the project. The responsibility of the project was assigned to the U.S. Army.
On August 13, 1942, the Manhattan Engineer District was established. About a month later, General Leslie R. Groves of the Corps of Engineers was put in complete charge of all the Army's responsibility relating to atomic-bomb development. At that time there were three government-supported laboratories in the country, Columbia University, University of Chicago and University of California; one site was used for the transformation from uranium into plutonium, and two for separating Uranium-235 through electromagnetism and gas diffusion. J. Robert Oppenheimer was appointed supervisor of the trinity site, the site of the plutonium testing. He also had much to do with the recruiting of many scientists. Neils Bohr was another man that worked on the project and helped develop the bomb. Bohr was important for the project, and also famous, because he developed the theory of fission and knew the subject better than anyone else.
Bohr had once stated that building an atomic bomb "can never be done unless you turn the United States into one huge factory". Years later, he told his colleague Edward Teller, "I told you it couldn't be done without turning the whole country into a factory. You have done just that". Enrico Fermi was the supervisor of the Chicago lab. He may have made the most important step to creating the bomb. At the University he created and sustained the first nuclear fission chain reaction, which was critical to creating an atomic bomb.
The only known type of atomic explosion at the time was fusion, or more commonly known as the hydrogen bomb. Fusion starts with a chain reaction, a nucleus of one atom splitting and releasing energy that causes more to split, and so on. This process is called fission. Neils Bohr paved the way for this discovery with his theory of fission. In less than one millionth of a second, fission produces about 100 million timed more energy than that of a chemical reaction, or the amount of energy used by the entire United States in half of a second. The first major challenge faced in the Manhattan project was the ability to find an acceptable and plentiful source of fuel for the bombs.
It was suggested by Bohr's theory that Uranium-235 could be used because it was unstable and could sustain a chain reaction. The problem with this was that U-235 was very hard to obtain, as was the only other candidate Plutonium-239. the only way the scientists could get enough of U-235 was by separating and refining it from U-238. There were three methods of separating the different uranium isotopes: magnetic, gaseous diffusion and gas centrifuge. Of the three methods, diffusion was the only one that was proficient and fast enough. The process of gaseous diffusion was used to separate the slightly lighter U-235 isotopes from the U-238. during this process the Uranium ore is sprayed with fluorine to form Uranium Hexafluoride gas. The gas is injected into a series of porous filters.
These filters are very fine and let the lighter gas pass through faster. Plutonium-239 was used as the fuel for another bomb, but this was also in short supply and there was no way to get this isotope from another and plutonium was more challenging to use because it was not as fissionable as uranium. There where many events that happened that would cause great controversy before the bomb could be tested. One major event was the death of President Roosevelt in April; President Truman would be taking office and would have to be updated. The project was so secret that President Truman knew nothing of its existence until he took the oath of office. Another event that affected the test was the surrender of Germany in May.
Even though the war with Japan was still continuing, many scientists did not believe it was necessary to use the bomb to end the war. The scientists were so wrapped up in the technical questions that they had to ignored the philosophical ones. The test would proceed as scheduled. The Manhattan project had three testing sites for developing the atomic bomb.
The one site used for creating the plutonium bomb was called the trinity site and it was located at Alamogordo, New Mexico. The valley, between the Rio Grande River and the Sierra Obscura mountains, was called the Jornada del Muertos. After years of hard work and theoretical calculations, the scientists were ready to see if their bomb would work. On the morning of 16 July 1945, the plutonium bomb was tested creating the first atomic bomb explosion. The explosion of the bomb was equivalent to about twenty thousand tons of TNT.
The plutonium bomb was code-named "fat man", simply because it was much rounder than the uranium bomb, which was called "little boy". The uranium bomb was easier to make than the plutonium bomb because Uranium is a much more fissionable isotope. But the bomb could not be tested because the resources where very rare, so a test bombing was not available. Therefore the bomb would have to be simple and guaranteed to work. The bomb needed about 50 kilograms of pure uranium, but the uranium obtained was hardly ever pure, so large amounts would be needed. So the required mass was about 100 kilograms, or 220 pounds.
Because uranium is more fissionable, the bomb would be based on a gun-type detonator. Basically, a section of uranium would be shaped with a center section missing. The center section would be place away from the uranium mass. An explosive would be used to propel the center section into the large section. The sections would then weld together and start the reaction. The destructions caused by this reactions were devastating.
On 6 August 1945, the first bomb was dropped on the city of Hiroshima by a B-29 Enola Gay piloted by Col. Paul Tibbetts. The bomb was "little boy", the uranium bomb. Three days later the second bomb, "fat man", was dropped on Nagasaki. The explosion of the uranium atomic bomb created overwhelming results.
About a half-mile radius from the point of where the bomb was detonated was called the vaporization point, which had 98 percent fatalities. Everything was destroyed in this area, nothing survived. Bodies were either missing pieces or burned so much that they could not be recognized. The temperature immediately rose to 3000 to 4000 degrees Celsius. About a one mile radius is called the destruction zone; every above ground building is destroyed. Up to a two mile radius from the hypocenter is the severe blast damage, it has 65% fatalities and 30% injury.
It destroys all large structures, damaging bridges, roads and even making rivers flow against the current. The severe heat damage area burns everything within two and a half miles. 50% of the people in this area die from suffocation, because the fires are using up the oxygen in the air. Up to a three miles from the initial point of the bombing is the severe fire and wind area.
15% of the people in this area die and half of the people are injured. People where blown around and suffered second and third degree burns, if they survived. The total amount of people killed in the first bombing was somewhere between 35,000 and 55,000. The affect of the bombs was powerful, but used in an inhumane and questionable way. The blow was too much for Japan. On 14 August 1945, five days after the second bomb had been dropped, Japan surrendered, ending the Second World War.
Ultimately, the United States got the result they wanted, which was to end the war; but many people question whether the bomb was necessary to end the war or that too many innocent lives were destroyed. President Truman was convinced that this was the only way to make the aggressive Japanese to surrender. The U.S. had made a choice; that choice was to protect their own soldiers, by not making them go into Japan, over the protection of Japanese Citizens. I believe that the bomb was not necessary to end the war, but the casualties of war would have been close to as many as was killed in the bombing, and the United States felt it necessary to protect its people.
The good thing about the Manhattan Project and the development of the atomic bomb was that they brought a quick end to the war, but also a new era in warfare.