EINSTEIN'S NEW THEORY — INFELD 197 



Although Einstein's new theory has many attractive features, we 

 do not yet know whether it is a successful unitary field theory ; we do 

 not know whether it contains solutions that can be interpreted as 

 elementary particles. We know that the old Maxwell and Einstein 

 theories did not give solutions of field equations that could be re- 

 garded as particles. In the old theories, the existence of matter had 

 to be assumed independently. Will the new theory succeed where 

 the old theories failed ? This is a crucial question, and we do not as 

 yet know the answer. 



But the situation is still more complicated. The modern develop- 

 ment of physics concerns quantum laws which are valid inside the 

 atom. It is not clear whether, and in what way, such laws could be 

 deduced from Einstein's field theor3\ Yet one should not be too 

 skeptical. Einstein's work has always met temporarily with skep- 

 ticism because his genius was ahead of his times. This happened 

 twice, and it may have happened again at the turn of our half- 

 century. 



