PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



WASHINGTON ACADEMY OF SCIENCES, PHILOSOPHICAL, 

 AND BOTANICAL SOCIETIES 



A joint meeting of the Philosophical Society with the Washington 

 Academy of Sciences was held October 28, 1911. President Clarke 

 of the Academy introduced Prof. Arthur Schuster, who spoke on 

 The foundations of physics. 



This subject is one that affects the whole of physical science. There 

 is at the present moment a general feeling of unrest which has definitely 

 altered some of our scientific beliefs and shaken our belief in others. 

 The great discoveries of recent years have revolutionized our ideas of 

 matter and force which we had considered settled. We must often 

 accept revolutions when they are accomplished, tho we may not like 

 them, but we may also bear in mind the warning of Kepler, and in the 

 words of a German proverb, be careful when emptying the bath-tub not 

 to turn out the baby with the dirty water. 



The science most of us have learned in our youth was based on the 

 laws of motion, established by Galileo, Huygens and Newton. Its 

 fundamental principles were : Constancy of Mass ; Action and Reaction, 

 involving Constancy of Momentum; to these was added later Conserva- 

 tion of Energy. The consideration of these together led to the view that 

 they could explain all physical phenomena, giving the materialistic sys- 

 tem of which we may take Kelvin as the most typical exponent. The 

 phenomena of light added the ether as a definite substance being able 

 to contain energy and therefore possessing mass. To Kelvin the ether 

 could have no properties not inherent in ordinary matter. The third 

 law of Newton in the past was true affecting matter only, but if necessary 

 ether may contain momentum; this requires a revision of our ideas con- 

 cerning the laws of motion. 



There has always been a concurrent stream of metaphysics as illus- 

 trated in some of the writings of Kirchhoff, Hertz, Mach and others. 

 But independently, the idea of the Conservation of Energy introduced 

 quasi-metaphysical ideas such as Potential Energy, Energy Paths, and 

 the Atomic Constitution of Energy. Physical science must get rid of 

 the metaphysics, and a good deal of unnecessary trouble existing in our 

 ideas on physics is due to the tendency to mix physics and metaphysics. 



( Joncerning the question of cause and effect, the doctrine of Kirch- 

 hoff that in physical science it is only necessary to describe things as they 

 are and not to explain them, is not sufficient nor is it physics. 



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