SCIENCE, YESTERDAY, TODAY, TOMORROW — SWANN 241 



from source to image. Later came the wave picture of light, and 

 later still the picture characteristic of the quantum theory. However, 

 even today, the optician who insisted on making spectacles with philo- 

 sophic regard to all the features of the quantum theory would soon 

 go out of business. No; the optician makes his spectacles with no 

 thoughts in mind other than those of his forerunners who thought en- 

 tirely in terms of rays for all optical phenomena 300 years ago. 



It becomes increasingly important that the physicist, who has 

 attained success in much of his specialized field by invoking certain 

 principles, should not fail to inquire as to the extent to which those 

 principles may play a leading role in other domains in which, perhaps, 

 as yet they have not been utilized. 



THE ROLE OF PATTERN 



The atomic physicist has been brought up to tliink in terms of par- 

 ticles with what he calls forces between them. He learned to do this 

 in the early birth of astronomy and has clung to the procedure. In the 

 beginning the procedure was to seek the laws of motion of the particles. 

 Thus, if, in astronomy, one gave the positions and velocities of the 

 heavenly bodies at some instant, the laws were such as to spell out step 

 by step how each of them moved ; and in terms of those positions and 

 velocities originally assigned, tell the inevitable story of what happens 

 subsequently. In terms of positions and velocities taken as starting 

 points, the system was one of predetermination. All motions calculable 

 in this way, and consistent with some initially assigned sets of positions 

 and velocities, were regarded as possible. Of course, different starting 

 points resulted in very different developments. In some cases we 

 should realize a body like a sun with other bodies traveling in circles or 

 ellipses around it. In other cases, we should have bodies coming in 

 from outer space, visiting the sun for a brief period, and returning to 

 infinity by other paths. In still other cases, bodies would interweave 

 their ways in complicated paths among their fellows. There were, in 

 fact, innumerable i^att-erns which could evolve from different starting 

 points, and each of these patterns had its own peculiarity mherent in its 

 own particular starting point. Thus, all sorts of different astronomical 

 universes were possible insofar as the motions of the bodies which con- 

 stituted them were concerned. However, the custom was not to con- 

 cern oneself too much with the patterns as fundamental, but rather to 

 regard them merely as the consequences of the particular positions 

 and velocities which, by chance, had been originally specified. 



When science came to regard atoms as groups of particles, the same 

 kind of procedures was envisaged ; althougli the laws of motion of the 

 particles were spelled out in different fashions when other things like 

 electromagnetic radiations became involved and claimed a place for 



