288 ANNUAL REPORT SMITHSONIAN INSTITUTION, 193 3 



With the disappearance of matter as a basic entity the funda- 

 mentals of physics can best be described as disembodied ghosts mas- 

 querading under mathematical formulas, 



" Hindsight is better than foresight." We could hardly expect 

 this crash to have been foreseen, yet it is now clear that the concept 

 of matter was doomed from the time that the trend set in against it. 

 The progress of human thought is like that of some mighty glacier, 

 slow but irresistible. 



The atom has always been a subject of interest to physicists, and 

 many speculations as to its nature have been advanced. When mat- 

 ter was an unquestioned axiom, the atom was explained on a ma- 

 terial basis. Newton says in his " Opticks " : 



All things considered, it seems probable to me that God in the beginning 

 formed matter in solid, massy, hard, impenetrable, movable particles, of 

 such sizes, figures, and with such other properties, and in such proportion 

 in space as most conduced to the end for which He formed them, and that 

 these primitive particles, being solids, are incomparably harder than any 

 porous bodies compounded of them ; even so very hard as never to wear or 

 break to pieces ; no ordinary power being able to divide what God himself 

 made one in the first creation. 



With the growth of the concept of the ether there was a parallel 

 tendency to explain atoms as ethereal phenomena. Kelvin suggested 

 that an atom might be a vortex ring in the ether, something like a 

 smoke ring in air. With the merging of matter into energy the 

 difficulty of explaining the nature of the atom increased greatly, yet 

 the interest in the subject has shown no sign of diminution. 



Twentieth-century experiment indicates that the atom is built up 

 in some way of positive and negative charges of electricity. The 

 present tendency is to regard the atom as electrical in its essence 

 without committing ourselves to any definite hypothesis as to the 

 nature of electricity. This electrical structure has taken several 

 forms. Bohr's " solar sj^stem " model of the atom has " had its day 

 and ceased to be." As far as our present ideas are capable of non- 

 mathematical expression, the atom is to be considered as a collection 

 of probabilities that an electric charge will be found here or there 

 at points in a definite space pattern. 



Nebulous and hazy as are our present ideas of the atom, it is 

 evident that this condition is but a corollary to the parallel change 

 that has taken place in our concept of matter, for if we have no clear 

 idea of the whole, how can we know more about its parts ? We have 

 seen that this change has come as the consequence of an attempt to 

 apply the principle of simplicity and economy in thought as laid 

 down by Occam and Newton. We physicists submit therefore that 

 as far as matter and the atom are concerned the present state of 

 physical theory is not our fault, but is the result of attempting to 

 apply to our subject the most approved rule of philosophy. 



