The Quantum Theory of the Emission and （辐射的量子理论）.pdf

P.A.M. Dirac, Proc. Roy. Soc., A114, 243 1927 The Quantum Theory of the Emission and Absorption of Radiation. P. A. M. Dirac, St. John’s College, Cambridge, and Institute for Theoretical Physics, Copenhagen. (Communicated by N. Bohr, For. Mem. R.S. – Received February 2, 1927.) — — ♦ — — Reprinted in “Quantum Electrodynamics”, edited by Julian Schwinger — — ♦ — — § 1. Introduction and Summary. The new quantum theory, based on the assumption that the dynamical variables do not obey the commutative law of multiplication, has by now been developed sufficiently to form a fairly complete theory of dynamics. One can treat mathematically the problem of any dynamical system com- posed of a number of particles with instantaneous forces acting between them, provided it is describable by a Hamiltonian function, and one can interpret the mathematics physically by a quite definite general method. On the other hand, hardly anything has been done up to the present on quantum electrodynamics. The questions of the correct treatment of a sys- tem in which the forces are propagated with the velocity of light instead of instantaneously, of the production of an electromagnetic field by a mov- ing electron, and of the reaction of this field on the electron have not yet been touched. In addition, there is a serious difficulty in making the theory satisfy all the requirements of the restricted principle of relativity, since a Hamiltonian, function can no longer be used. This relativity question is, of course, connected with the previous ones, and it will be impossible to 1 answer any one que