par Frank da Cruz
et des choses qui ont eu une importance colossale sur l'histoire de notre planète.
Excellent et captivant.
Merci à Frank da Cruz
Enrico Fermi, Leo Szilard, Walter Zinn, Herbert Anderson, and others begin work on nuclear fission in Columbia's Pupin Hall. Within a few months this work would become the Manhattan Project, funded by President Roosevelt (Columbia Law, 1905-07) in response to Albert Einstein's letter warning of Nazi research in this area. After Pearl Harbor, the project moved to the University of Chicago (supposedly to make it less vulnerable to German attack) and spread to the University of California, Los Alamos, Oak Ridge, Hanford, and other locations. Fermi's lab was in the same building as Professor Eckert's Astronomical Computing Bureau. I don't know to what degree, if any, Eckert's computing machines were employed in the early Manhattan Project, but as noted below they played a key role in 1945 in the final preparations for the first A-bombs . A number of other Columbia scientists worked on the project, including I.I. Rabi, Edward Teller, John Dunning (who identified U-235 as the fissionable uranium isotope using the Pupin cyclotron in Feb 1940), Harold Urey (who later left the project on moral grounds), and George Pegram (who assembled the original Manhattan Project team), as well as junior faculty who would later become well-known physicists, such as C.S. Wu and Bill Havens (both of whom I worked for in my student days), James Rainwater, Eugene Booth, and Richard Present. The following is taken from a narrative, Evolving from Calculators to Computers on the Los Alamos National Laboratory History website (May 2003):
Calculations at Los Alamos were originally done on manually operated mechanical calculators, which was not only laborious and time-consuming, but the machines broke down frequently under heavy use. The only one who could fix them promptly was Richard Feynman (Nobel Prize in Physics, 1965), which some thought was not the best use of his time. "Dana Mitchell, whom Laboratory Director J. Robert Oppenheimer had recruited from Columbia University to oversee procurement for Los Alamos, recognized that the calculators were not adequate for the heavy computational chores and suggested the use of IBM punched-card machines. He had seen them used successfully by Wallace Eckert at Columbia to calculate the orbits of planets and persuaded [Stanley] Frankel and [Eldred] Nelson to order a complement of them.
"The new IBM punched-card machines were devoted to calculations to simulate implosion, and Metropolis and Feynman organized a race between them and the hand-computing group. 'We set up a room with girls in it. Each one had a Marchant. But one was the multiplier, and another was the adder, and this one cubed, and all she did was cube this number and send it to the next one,' said Feynmann. For one day, the hand computers kept up: 'The only difference was that the IBM machines didn't get tired and could work three shifts. But the girls got tired after a while.'"
Now that Germany's defeat was imminent, Leo Szilard — who, with Enrico Fermi, had initiated the Manhattan Project at Columbia in 1939 — did not believe the A-bomb should be used on Japan. He obtained a letter of introduction to President Roosevelt from Albert Einstein so he could present his case against dropping the bomb. A preliminary meeting with Eleanor Roosevelt was set up for May 8th, but the President died on April 12th and Szilard was blocked from contacting President Truman.
8 May 1945:
VE Day, Germany surrenders, the war in Europe ends.
Szilard wrote and circulated a petition among his fellow scientists at the University of Chicago against the use of atomic weapons and asking President Truman not to use them on Japan. He also sent copies to Oak Ridge and Los Alamos for circulation (the Los Alamos copy was buried by Groves and Oppenheimer). Szilard's petition went through several drafts; the first one (July 3rd) included the following text:
Atomic bombs are primarily a means for the ruthless annihilation of cities. Once they were introduced as an instrument of war it would be difficult to resist for long the temptation of putting them to such use. The last few years show a marked tendency toward increasing ruthlessness. At present our Air Forces, striking at the Japanese cities, are using the same methods of warfare which were condemned by American public opinion only a few years ago when applied by the Germans to the cities of England. Our use of atomic bombs in this war would carry the world a long way further on this path of ruthlessness.
Subsequent drafts were toned down a bit but made the same recommendations. The Oak Ridge petition urged that "before this weapon be used without restriction in the present conflict, its powers should be adequately described and demonstrated, and the Japanese nation should be given the opportunity to consider the consequences of further refusal to surrender". Watson Lab staff who were performing calculations for Los Alamos were unaware of the petitions or, indeed (with only two exceptions, Eckert and Grosch, the only ones with security clearances), that the calculations were for a bomb . In any event, the petitions never reached the President.
6 Aug 1945:
Hiroshima: "Now we knew what we had been working on" . A second A-bomb was dropped on Nagasaki August 9th. More than 200,000 people died from the two blasts."