when did democritus discovered the atom?
6129 Demokritos
neutral
 Fears of a fizzle led to the construction of a steel containment vessel called Jumbo that could contain the plutonium , allowing it to be recovered , but Jumbo was not used . A rehearsal was held on May 7 , 1945 , in which 108 long tons ( 110 t ) of high explosive spiked with radioactive isotopes were detonated . The Gadget 's detonation released the explosive energy of about 22 kilotons of TNT ( 92 TJ ) . Observers included Vannevar Bush , James Chadwick , James Conant , Thomas Farrell , Enrico Fermi , Richard Feynman , Leslie Groves , Robert Oppenheimer , Geoffrey Taylor , and Richard Tolman . 

neutral
 Fears of a fizzle led to the construction of a steel containment vessel called Jumbo that could contain the plutonium , allowing it to be recovered , but Jumbo was not used . A rehearsal was held on May 7 , 1945 , in which 108 long tons ( 110 t ) of high explosive spiked with radioactive isotopes were detonated . The Gadget 's detonation released the explosive energy of about 22 kilotons of TNT ( 92 TJ ) . Observers included Vannevar Bush , James Chadwick , James Conant , Thomas Farrell , Enrico Fermi , Richard Feynman , Leslie Groves , Robert Oppenheimer , Geoffrey Taylor , and Richard Tolman . 

neutral
 The most optimistic search project to date was Project Ozma , which was intended to " search for extraterrestrial intelligence " ( SETI ) by examining selected stars for indications of artificial radio signals . It was run by the astronomer Frank Drake , who selected Tau Ceti and Epsilon Eridani as the initial targets . Both are located near the Solar System and are physically similar to the Sun . No artificial signals were found despite 200 hours of observations . Subsequent radio searches of this star system have also turned up negative . 

contradiction
 News of the discovery of nuclear fission by German chemists Otto Hahn and Fritz Strassmann in 1938 , and its theoretical explanation by Lise Meitner and Otto Frisch , was brought to the United States by Niels Bohr . Based on his liquid drop model of the nucleus , he theorized that it was the uranium @-@ 235 isotope and not the more abundant uranium @-@ 238 that was primarily responsible for fission with thermal neutrons . To verify this Alfred O. C. Nier at the University of Minnesota used a mass spectrometer to create a microscopic amount of enriched uranium @-@ 235 in April 1940 . John R. Dunning , Aristid von Grosse and Eugene T. Booth were then able to confirm that Bohr was correct . Leo Szilard and Walter Zinn soon confirmed that more than one neutron was released per fission , which made it almost certain that a nuclear chain reaction could be initiated , and therefore that the development of an atomic bomb was a theoretical possibility . There were fears that a German atomic bomb project would develop one first , especially among scientists who were refugees from Nazi Germany and other fascist countries . 

contradiction
 News of the discovery of nuclear fission by German chemists Otto Hahn and Fritz Strassmann in 1938 , and its theoretical explanation by Lise Meitner and Otto Frisch , was brought to the United States by Niels Bohr . Based on his liquid drop model of the nucleus , he theorized that it was the uranium @-@ 235 isotope and not the more abundant uranium @-@ 238 that was primarily responsible for fission with thermal neutrons . To verify this Alfred O. C. Nier at the University of Minnesota used a mass spectrometer to create a microscopic amount of enriched uranium @-@ 235 in April 1940 . John R. Dunning , Aristid von Grosse and Eugene T. Booth were then able to confirm that Bohr was correct . Leo Szilard and Walter Zinn soon confirmed that more than one neutron was released per fission , which made it almost certain that a nuclear chain reaction could be initiated , and therefore that the development of an atomic bomb was a theoretical possibility . There were fears that a German atomic bomb project would develop one first , especially among scientists who were refugees from Nazi Germany and other fascist countries . 
