1 I
APRIL. 1848
239
a description of the experimental confimrution by Heinrich Hertz, in 1887, of the "highly mathematical theory concerning light, electricity, and magnetism proposed twenty-three years before hy the Scottish ohvsicist. James Clerk Maxwell." In order to transmit the elec&o-gne'tic waves, physicists assumed the existence of a "luminiferous ether," whose only reason for existing was to function as subject far the verb "undulates!' The struggle between the dart theory proposed hy Sir Iswe Newton and the wave theory suggested by Huygens finally ended apparently in a complete victory for the adherents of the latter. In Chapter 11, which is presentea by the author as the fist Bcene of Act I of the drama, the story is told of the manner in which Planck was led to conceive the quantum hypothesis. Thus was introduced into nhvsics the mvsterious constant "h!' Whereas Planck was somewhat apologetic in expressing his ideas, Einstein (1905) boldly went the whole way and "developed the startling idea of a definite atomicity of energy." This is the topic of Chapter 111. Is light a wave or particle? In Chapter IV, entitled "Tweedledumand Tweedledee," there are described the results obtained by C. T. R. Wilson, A. H. Compton, and R. A. Millikan. The physicists "could but make the best of it, and went around with woebeeone faces sadlv comnlainine that on Mondws. Wednesdays, ind Fridays they must lookon light as a. waye;' an Tuesdays, Thursdays and Saturdays, as a particle. On Sundays they simply prayed." Meantime Rutherford had ~roposedhis nuclear model of the atom and Niels Bohr combined this model dong withthe quantum hypothesis and classical dynamics to formulate a theory of energy levels for atomic systems which yielded not only s n interpretation of the oriein of soectra lines but also a value for the Rydberg. constant based sd~elyon values of e, m, and h) in excellentagre& ment with the value observed by spectroscopists. To determine the electron orbits Bohr introduced a quantum condition and to account for the relative brightness of spectral lines he added another rule which he called the correspondence principle. These developments and the Pauli exclusion principle are discussed in Chapters V and YT. Chaprrr VII is entitled, "Inttrmczzo, Aurhor'n Warning to the Hwdcr." This is folloa~dIn. ".ict 11." c o n s i r t i n ~ dsewn chapters on the new Quantum ~ i c h a n i c ks t h which
