SCIENCE, YESTERDAY, TODAY, TOMORROW — 3WANN 237 



And so, after a time, the man in the street learns to regard the be- 

 havior of the atomic bomb as something not too much to be marveled 

 at, and he accepts it as he has accepted radio or as, at an earlier time, 

 he had accepted the ordinary phenomena of electricity, the running of 

 streetcars as the result of something peculiar happening in copper 

 cables which, by some mysterious means, are said to transmit electric 

 power. He accepts these things as in a still earlier epoch he accepted 

 the motions of the heavenly bodies as phenomena not to be denied, 

 phenomena familiar in the experience of all, but j)henomena which 

 did not seem to weld together with the idea of action through contact, 

 which the naive intuition of the day seemed to regard as a natural 

 haven of contentment in the understanding of all things. 



Now, in spite of all I have said to persuade you that we live in a 

 world of miracles, you will perhaps be unhappy about my definition 

 of that term. You may prefer to regard a miracle as a thing of such 

 unusual occurrence, that the fact of its having occurred at all is open 

 to doubt. You may then maintain that atomic phenomena are not 

 miracles because they are always occurring, and their continual occur- 

 rence provides, in its totality, for the phenomena evident around us. 

 If you say this, I fear that the Lord hath delivered you into mine 

 hands ; for in this sense, practically all the phenomena of the atomic 

 world would indeed be miracles to any supposed inhabitants of the 

 atom. 



Consider the emission of an X-ray from an atom. Even if, in imag- 

 ination, you lived on one of the atoms which compose the part of the 

 X-ray tube from which the X-rays come, so rare would be the emission 

 of a ray from an individual atom that you would be put in an atomic 

 lunatic asylum if, as a resident of such an atom, you maintained that 

 any such phenonemon had ever occurred. Only because there are so 

 many atoms does the physicist observe a strong emission of X-rays 

 from the X-ray tube. And so, what is a miracle to the resident of the 

 atom is no longer a miracle to him who observes a multitude of atoms. 

 A similar remark applies to practically every phenomenon in atomic 

 physics. 



A cosmic ray, passing through this room, detaches an electron from 

 an atom here and there, and by observing this phenomenon we investi- 

 gate and measure the rays. Yet, to the individual atom, this theft of 

 an electron by a cosmic ray is such a rare event that the chance of its 

 happening to any particular atom in the period of, let us say a day, is 

 no more than the chance that one of you would be murdered in that 

 day if, with the earth at its present population, only one murder were 

 committed in 300 years. 



And so it is with all the happenings of atomic physics. And yet it 

 is these miraculous happenings which, in their totality, produce all 

 the interesting things which our coarse-grained senses observe. And 



