Einsteinwrote a letter to President Franklin D.
Roosevelt. Urged byHungarian-born physicists Leo Szilard, Eugene Wingner, and EdwardTeller, Einstein told Roosevelt about Nazi German efforts to purifyUranium-235 which might be used to build an atomic bomb. Shortly afterthat the United States Government began work on the Manhattan Project. The Manhattan Project was the code name for the United States effortto develop the atomic bomb before the Germans did. “The firstsuccessful experiments in splitting a uranium atom had been carriedout in the autumn of 1938 at the Kaiser Wilhelm Institute inBerlin”(Groueff 9) just after Einstein wrote his letter. So the racewas on.
Major General Wilhelm D. Styer called the Manhattan Project”the most important job in the war . . . an all-out effort to build anatomic bomb. “(Groueff 5) It turned out to be the biggest developmentin warfare and science’s biggest development this century.
The mostcomplicated issue to be addressed by the scientists working on theManhattan Project was “the production of ample amounts of ‘enriched’uranium to sustain a chain reaction. “(Outlaw 2) At the time,Uranium-235 was hard to extract. Of the Uranium ore mined, only about1/500 th of it ended up as Uranium metal. Of the Uranium metal, “thefissionable isotope of Uranium (Uranium- 235) is relatively rare,occurring in Uranium at a ratio of 1 to 139. “(Szasz 15) Separating theone part Uranium-235 from the 139 parts Uranium-238 proved to be achallenge. “No ordinary chemical extraction could separate the twoisotopes.
Only mechanical methods could effectively separate U-235from U-238. “(2) Scientists at Columbia University solved thisdifficult problem. A “massive enrichment laboratory/plant”(Outlaw 2)was built at Oak Ridge, Tennessee. H.
C. Urey, his associates, andcolleagues at Columbia University designed a system that “worked onthe principle of gaseous diffusion. “(2) After this process wascompleted, “Ernest O. Lawrence (inventor of the Cyclotron) at theUniversity of California in Berkeley implemented a process involvingmagnetic separation of the two isotopes. “(2) Finally, a gas centrifugewas used to further separate the Uranium-235 from the Uranium-238.
TheUranium-238 is forced to the bottom because it had more mass than theUranium-235. “In this manner uranium-235 was enriched from its normal0. 7% to weapons grade of more than 90%. “(Grolier 5) This Uranium wasthen transported to “the Los Alamos, N.
Mex. , laboratory headed by J. Robert Oppenheimer. “(Grolier 5) “Oppenheimer was the major forcebehind the Manhattan Project. He literally ran the show and saw to itthat all of the great minds working on this project made theirbrainstorms work.
He oversaw the entire project from its conception toits completion. “(Outlaw 3) Once the purified Uranium reached NewMexico, it was made into the components of a gun-type atomic weapon. “Two pieces of U-235, individually not large enough to sustain a chainreaction, were brought together rapidly in a gun barrel to form asupercritical mass that exploded instantaneously. “(Grolier 5) “It wasoriginally nicknamed ‘Thin Man'(after Roosevelt, but later renamed’Little Boy’ (for nobody) when technical changes shortened theproposed gun barrel. “(Szasz 25) The scientists were so confident thatthe gun-type atomic bomb would work “no test was conducted, and it wasfirst employed in military action over Hiroshima, Japan, on Aug. 6,1945.
“(Grolier 5) Before the Uranium-235 “Little Boy” bomb had beendeveloped to the “point of seeming assured of success,”(Grolier 5)another bomb was proposed. The Uranium-238 that had been earlier ruledout as an option was being looked at. It could capture a free neutronwithout fissioning and become Uranium-239. “But the Uranium-239 thusproduced is unstable (radioactive) and decays first to neptunium-239and then to plutonium-239. “(Grolier 5) This proved to be usefulbecause the newly created plutonium-239 is fissionable and it can “beseparated from uranium by chemical techniques,”(6) which would be farsimpler than the physical processes to separate the Uranium-235 fromthe Uranium-238.
Once again the University of Chicago, under EnricoFermi’s direction built the first reactor. “This led to theconstruction of five large reactors at Hanford, Wash. , where U-238 wasirradiated with neutrons and transmuted into plutonium. “(6) Theplutonium was sent to Los Alamos. The problem to overcome in thedevelopment of the plutonium bomb was an isotope of plutonium.
Thescientists feared this isotope would cause premature detonation andmost of the plutonium would blow apart before it could all fission. “To overcome this so-called ‘defect of nature, ‘ the plutonium had tobe brought into a supercritical mass far faster than conventionalballistics could achieve. “(Grolier 6) Physicist Seth Neddermeyer andmathematician John von Neumann devised the theory of “implosion. ” Asubcritical sphere of plutonium was surrounded by chemicalhigh-explosives. The 5,300 pounds of explosives were all “carefullyshaped as ‘lenses.
‘ When these were detonated, they focused the blastwave so as to compress the plutonium instantly into a supercriticalmass. “(Szasz 25) This was much more complex, and many people doubtedthat it would work. There was a debate at Los Alamos about whether totest the new plutonium ‘implosion’ bomb before it was actuallydropped. “Harvard explosives expert George B. Kistiakowsky andOppenheimer both argued for such a test, but initially Groves wasopposed. He was afraid that if the test failed, the precious plutoniumwould be scattered all across the countryside.
“(Szasz 26) BrigadierGeneral Leslie R. Groves, the man the army placed in charge, waseventually persuaded. Hanford’s plutonium production was increasingfast enough so that a test would cause little delay in time. Theyfeared that if they dropped the untested plutonium bomb and it failedto work, “the enemy would find themselves owners of a ‘gift’ atomicweapon. “(Szasz 26) The final agreement for the test was that the bombwould be placed in “a gigantic, 214-ton, cylinder-shaped tank (called’Jumbo’). “(Szasz 26) If the plutonium correctly fissioned, the tankwould be vaporized.
If it did not work correctly, the conventionalexplosives would be contained in the tank and the plutonium would stayin the tank. After further development of the implosion design andfears that “Jumbo” would dramatically distort all “their complicatedinstrumentation-the raison d’tre for the test,”(Szasz 36) theworld’s largest pressure tank was not used. On Monday, July 16, 1945,at 5:29:45 A. M. , Mountain War Time, the plutonium bomb ignited at theTrinity site, a remote site in the New Mexico desert.
“The explosioncreated s brilliant flash that was seen in three states. “(Szasz 83)There were many reports from civilians from all over that describedthe experience. People who saw it said it looked like the sun hadrisen for a few minutes and then went back down. Others thought theyhad seen a large plane or meteor crash. A sheep herder who was layingsleeping on a cot fifteen miles away was blown off. “The SmithsonianObservatory on Burro Mountain confirmed a shock but noted that thevibrations were unlike any earthquake ever recorded.
“(Szasz 84) Aneight year-old boy was awakened and ran for his Methodist parents, andthey considered if this might be the end of the world. The mostpowerful statement that has been cited in practically every coverageof the atomic bomb is Georgia Green’s experience. She was being drivento Albuquerque. “What was that?” she asked her brother-in-law, who wasdriving. This was very unusual because Georgia Green was blind. Brigadier General Farrell wrote a letter for the Secretary of War.
“‘No man-made phenomenon of such tremendous power had ever occurredbefore . . . Thirty seconds after the explosion came, first, the airblast pressing hard against people and things, to be followed almostimmediately by the strong, sustained, awesome roar which warned ofdoomsday and made us feel that we puny things were blasphemous to daretamper with forces heretofore reserved to the Almighty. Words areinadequate tools for the job of acquainting those not present with thephysical, mental and psychological effects. “(Groueff 355) Uponwitnessing the explosion, reactions among the bomb’s creators weremixed.
Their mission had been successfully accomplished, however, theyquestioned whether “the equilibrium in nature had been upset — as ifhumankind had become a threat to the world it inhabited. “(Outlaw 3)Oppenheimer was ecstatic about the success of the bomb, but quoted afragment from Bhagavad Gita. “I am become Death, the destroyer ofworlds. ” Many people who were involved in the creation of the atomicbomb signed petitions against dropping the bomb. The atomic bomb hasbeen used twice in warfare. The Uranium bomb nicknamed “Little Boy,”which weighed over 4.
5 tons, was dropped over Hiroshima on August 6,1945. At 0815 hours the bomb was dropped from the Enola Gay. It missedGround Zero at 1,980 feet by only 600 feet. “At 0816 hours, in theflash of an instant, 66,000 people were killed and 69,000 people wereinjured by a 10 kiloton atomic explosion. “(Outlaw 4) See blast rangesdiagram Nagasaki fell to the same treatment as Hiroshima on August 9,1945.
The plutonium bomb, “Fat Man,” was dropped on the city. Itmissed its intended target by over one and a half miles. “Nagasaki’spopulation dropped in one split-second from 422,000 to 383,000. 39,000were killed, over 25,000 were injured. That blast was less than 10kilotons as well.
Physicists who have studied the atomic explosionsconclude that the bombs utilized “only 0. 1% of their respectiveexplosive capabilities. “(Outlaw 4) Controversy still exists aboutdropping the two atomic bombs on Japan. Arguments defending theJapanese claim “the atomic bomb did not win the war in the Pacific; atbest, it hastened Japanese acceptance of a defeat that was viewed asinevitable. “(Grolier 8) Other arguments state that the United Statesshould have warned the Japanese, or that we should have invited themto a public demonstration.
“In retrospect that U. S. use of the atomicbomb may have been the first act of the cold war. “(Grolier 8) On theother side, advocates claimed that the invasion of the Japaneseislands could and would result in over one million military casualtiesplus the civilian losses based on previous invasions of Japaneseoccupied islands.
