large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_02_asimov_64kb_124
large/12904/worldswithinworlds_v1-3_1904_librivox_64kb_mp3/worldswithinworlds_02_asimov_64kb
English
12904
Uranium emitted gamma rays that we now know to be a hundred thousand times as energetic as ordinary light rays. What's more, alpha particles were being emitted at velocities of perhaps 30,000 kilometers per second, while the lighter beta particles were being shot off at velocities of up to 250,000 kilometers per second (about 0. URANIUM EMITTED GAMMARRAYS THAT WE NOW KNOW TO BE A HUNDRED THOUSAND TIMES AS ENERGETIC AS ORDINARY LIGHT RAYS WHAT'S MORE ALPHA PARTICLES WERE BEING EMITTED AT VELOCITIES OF PERHAPS THIRTY THOUSAND KILOMETERS PER SECOND WHILE THE LIGHTER BATEER PARTICLES WERE BEING SHOT OFF AT VELOCITIES OF UP TO TWO HUNDRED FIFTY THOUSAND KILOMETERS PER SECOND ABOUT Z
e maximum age of the earth was only 25 million years. Geologists and biologists found themselves disturbed by this. The slow changes in the earth’s crust and in the evolution of life made it seem very likely that the earth must have been in existence—with the sun delivering heat and light very much in the present fashion—for many hundreds of millions of years. Yet there seemed absolutely no other way of accounting for the sun’s energy supply. Either the law of conservation of energy was wrong (which seemed unlikely), or the painfully collected evidence of geologists and biologists was wrong (which seemed unlikely),—or there was some source of energy greater than any known in the 19th century, whose existence had somehow escaped mankind (which also seemed unlikely). Yet one of those unlikely alternatives would have to be true. And then in 1896 came the discovery of radioactivity. The Energy of Radioactivity It eventually became clear that radioactivity involved the giving off of energy.  OF THE EARTH WAS ONLY TWENTY FIVE MILLION YEARS GEOLOGISTS AND BIOLOGISTS FOUND THEMSELVES DISTURBED BY THIS THE SLOW CHANGES IN THE EARTH'S CRUST AND IN THE EVOLUTION OF LIFE MADE IT SEEM VERY LIKELY THAT THE EARTH MUST HAVE BEEN IN EXISTENCE WITH THE SUN DELIVERING HEAT AND LIGHT VERY MUCH IN THE PRESENT FASHION FOR MANY HUNDREDS OF MILLIONS OF YEARS YET THERE SEEMED ABSOLUTELY NO OTHER WAY OF ACCOUNTING FOR THE SUN'S ENERGY SUPPLY EITHER THE LAW OF CONSERVATION OF ENERGY WAS WRONG WHICH SEEMED UNLIKELY OR THE PAINFULLY COLLECTED EVIDENCE OF GEOLOGISTS AND BIOLOGISTS WAS WRONG WHICH SEEMED UNLIKELY OR THERE WAS SOME SOURCE OF ENERGY GREATER THAN ANY KNOWN IN THE NINETEENTH CENTURY WHOSE EXISTENCE HAD SOMEHOW ESCAPED MANKIND WHICH ALSO SEEMED UNLIKELY YET ONE OF THOSE UNLIKELY ALTERNATIVES WOULD HAVE TO BE TRUE THEN IN EIGHTEEN NINETY SIX CAME THE DISCOVERY OF RADIOA ACTIVITY THE ENERGY OF RADIOACTIVITY IT EVENTUALLY BECAME CLEAR THAT RADIOA ACTIVITY INVOLVED THE GIVING OFF OF ENERGY
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