THE SCIENTIFIC METHOD 115 



theory of probability, or the consensus of opinion of 

 the greatest number, working with the greatest care. 



The basic laws of physics are the laws of continuity 

 and conservation, and the law of cause and effect. 

 Unless we believe that something, matter, energy, or 

 both, remains unchanged in amount and has a continu- 

 ous existence however changed in appearance, and un- 

 less phenomena can be repeated, we have no certainty 

 of knowledge and no means of communicating ideas 

 to others. The discussion of the reality of these laws 

 may be left to the philosopher, but I dare say, however 

 he decides, they will continue to be accepted by man- 

 kind generally. 



The universality and application of these and other 

 laws should be rigidly limited to experience by the 

 physicist. The law of conservation requires that the 

 quantity of matter and energy is either infinite, which 

 means nothing, or that there is an exact interchange 

 in quantity in every action. This belief is expressed 

 in Newton's law that to every action there is an equal 

 and contrary reaction. But it is evident that conserva- 

 tion, as a scientific law which may be verified, is limited 

 to a very small category of observations and is only ap- 

 proximate for them. Thus we know nothing of the 

 total amount of energy radiated from the sun or where 

 it goes. Hypothesis here shows considerable vacilla- 

 tion. Some assert that the universe is infinite and so 

 the radiation never reaches a boundary; others say 



