Corpuscular Theory of Light and Gravitational Shift

Usually the prediction of spectral shift in the light coming from regions of higher gravitational potential is derived by considering the emitting atom as an oscillating mechanism, and the shift is connected with retardation of clocks. In this paper the question is considered from the point of view of the corpuscular theory of light in the form which it takes in the relativity theory. In the special theory the light ray is considered as given by a vector freely movable along the line of its direction. It follows that all rays of light are absolutely equal, the difference in color is due to the difference in position with respect to the reference system (Doppler effect). In the general theory motion of a vector along a curve leads to a geodesic; colors of different rays cannot be compared unless some universal time is introduced; this introduction is easy in the centrosymmetric case; in this case the discussion is completed and leads to the usual result.