The Spin of the Photon.

RECENTLY a number of papers have appeared on the question as to whether the phenomena of polarisation of light can be explained by the assumption of a `spin' of the photon.¹ Kastler and Frisch deduce from their experiments that the photon possesses no spin, and Kastler argues further that the phenomena of polarisation should be explained on statistical grounds. Hainan and Bhagavantam, on the other hand, argue that the interesting results obtained by Bar and Hanle² on the reversal of the state of polarisation of Baman lines when observed in the direction of propagation of the primary beam can be explained only on the assumption that the photons possess spin. They seem to link circular polarisation definitely with a spin of the photon about the line of propagation.