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Physical Background 

 of Evolution 



The fundamental unity of the universe has become more 

 and more apparent since the turn of the century. Quantum 

 mechanics and relativity with its concepts of the equiva- 

 lence of matter and energy and the indivisibility of space 

 and time have given physicists a description of this unity in 

 terms of mathematical relationships. In spite of the definitely 

 limited senses of perception with which man is equipped, a 

 picture of the universe, however tenuous and wraithlike, is 

 beginning to appear; and the order that runs through this 

 picture is something on which all minds can concur. 



From relatively few, fundamental subatomic particles the 

 great variety of physical substance is built up, first into the 

 92 natural elements, hydrogen to uranium, then into molec- 

 ular combinations of greater and greater complexity. We 

 know that the basic theories of the evolution of the elements 

 are sound since it has already been possible to duplicate 

 some of the processes involved. The splitting of the uranium 

 atom and the synthesis of helium from hydrogen in the fire 

 of this explosion, however menacing it may be to man, is 

 nevertheless incontestable proof of his assumptions. The na- 

 ture of the subatomic microcosm is now partially revealed, 

 and Einstein's unified field theory is expected, along with 

 other attacks on the problem, to reveal still more. This 



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