wien: recent theories of heat and radiation 277 



theory of quanta, but we do not yet know how to use this theory 

 to calculate the velocity of molecular vibrations thru the solid. 

 In considering Planck's new theory, we assume an amount of 



energy >, independent of temperature. To find the true law of 



radiation,, one must adopt a definite law of emission, and so obtain 

 a relation between the probability of emission and the rate of 

 increase of energy to the critical value hv. It would be freer from 

 objection to consider the law of radiation as determined by the 

 considerations offered by Debye, and then to derive inversely the 

 law of emission. 



The now well-known theory of electrons was founded on the 

 hypothesis that electric conductivity in metals is determined by 

 free electrons moving in the metal with complete irregularity. In 

 this form the theory can not hold, for H. A. Lorentz has shown 

 that such free electrons must yield a radiation following the law 

 of Rayleigh and Jeans. This radiation, especially for short waves, 

 would be many times greater than is found by observation. The 

 theory of specific heat also shows that only the molecules, not the 

 electrons, possess heat energy. 



One might perhaps hope to find a way out of the difficulty by 

 assuming that the number of electrons is small in comparison with 

 the number of atoms, but for low temperatures one would be 

 forced to apply Planck's formula, not only to the atoms but to the 

 electrons as well, and a new difficulty would at once result, since the 

 free electrons can not have a vibration frequency equal to v. If it 

 were possible to identify the v for an electron with the value for 

 an atom, the electrons could no longer be regarded as free and 

 there would be no difference between the free electrons and the 

 electrons fixed in the atom. All the electrons would take part 

 of the heat energy, and, their number being greater than the 

 number of atoms, the value of the specific heat for high tempera- 

 tures would be too high. There are many circumstances which 

 make it probable that the energy of the electrons is independent 

 of temperature. All emissions of electrons by radiation are inde- 

 pendent of temperature, and the electrons coming from hot bodies 

 can be emitted bv radiation. 



