THE UNIVERSE AND MATTER — LOUIS- JARAY 131 



The new physics differs essentially from the old in other respects: 

 The old mechanics had its dogmas; no velocity could be greater than 

 that of light; no temperature could be less than zero degrees absolute; 

 matter could not be destroyed, etc.; this last law is no longer recog- 

 nized. Most of the outstanding physicists, such as Eddington, admit 

 "the annihilation of matter" though it seems apparently supernatural. 

 One experiment shows that pairs of positive and negative electrons 

 are destroyed and produce pairs of photons of light, and in the opposite 

 sense the photons 6 produce pairs of positive and negative electrons ; 

 the first case appears to be a "dematerialization" and the second case 

 a "materialization," if the electrons are very small corpuscles but 

 material parts of the atom and if the photons, that is the radiations, 

 are not material corpuscles. Thus, says Einstein, in place of the 

 principle of the conservation of matter and of the conservation of 

 energy, it is necessary to substitute a simple principle of equivalence, 

 that of the "conservation of something," but permitting the con- 

 version of matter into energy and energy into matter. An example 

 shows this new conception in concrete fashion: An atom of helium 

 is formed from four atoms of hydrogen ; but the mass of the helium is 

 less by a small quantity than the sum of four atoms of hydrogen; 

 this small quantity of matter has changed into energy and the clamp- 

 ing together of the four atoms has liberated, it is said, 27 millions of 

 volts; thus the loss of mass, or loss of matter, is compensated, accord- 

 ing to the principle of equivalence, by the creation of energy. 



Thibaud interprets the results of such experiments as just described 

 by conceiving that it is the continuous destruction of matter in the 

 sun which liberates the luminous radiation. 7 In any case one can 

 imagine throughout the universe the transformation of atoms of 

 sidereal bodies into radiation, as in radioactivity, or the transforma- 

 tion of radiation ho to matter as in the experiment with photons of 

 gamma rays. 



One difficulty remains: We do not know with certainty what the 

 "photons" are, i. e., what light is. Louis de Broglie some 10 years 

 ago conceived, and soon the new physics adopted, his "wave mechan- 

 ics," applied first to light and then to all forms of energy. Newton 

 asserted that light consisted of an emission of corpuscles, Fresnel 

 that it consisted of waves in a tenuous medium, the ether, the existence 

 of which modern physicists doubt, Louis de Broglie reunited the two 

 theories and declared that what happens is wave motion and emission 

 at the same time, light waves and the projection of corpuscles of light, 

 called photons. Passing from light to matter, he asserted that it is 

 necessary to link together the idea of a wave with the movement of 

 material particles of the atom; the displacement of the material 



« In the experiment, the photons are produced by a radiation called gamma rays. 

 ' Vie et transmutation des atomes, p. 55. 

 11472S— 39 10 



