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For obvious reasons, Dr. Smyth's description of the bomb is incomplete. But he gives some hints. U-235 and plutonium do not have to be exploded by a detonator like TNT. They explode automatically whenever gathered together in large quantities. Therefore a main problem in an atomic bomb is to design a mechanism which will bring small masses to the explodable "critical size." Until the explosion is well started, they should be held together by a heavy-material "tamper." A possible source of heavy material: the hoarded gold of Fort Knox.
About the Future. Dr. Smyth's War Department report breaks off at the end of June 1945, shortly before the fearful test on the desert which proved the bomb a smash-hit (TIME, Aug. 13). Dr. Smyth was sure of success before the test was made, but he was not completely happy about it: "Initially, many scientists could and did hope that some principle would emerge which would prove that atomic bombs were inherently impossible. This hope has faded gradually. . . ."
For the future, rapid improvement in the technique of atom fission is foreseeable. For science this will be progress but, says Dr. Smyth: "Should a scheme be devised for converting to energy even as much as a few per cent of the matter of some common material, civilization would have a means to commit suicide at will."
-Named for the planet Pluto, which is beyond Uranus and Neptune in the solar system. Pluto was also the god of the underworld.