The twin paradox and time dilation have equivalents in polarization optics

Abstract

The phenomena known as the twin-paradox and time dilation, which are familiar effects in the special theory of relativity, have analogous counterparts in polarization optics. To show that, we present the concept of proper irradiance for a partially polarized lightwave. The analogous effect of the twin paradox is that the proper irradiance of the incoherent addition of two partially polarized lightwaves exceeds the sum of the proper irradiances of each individual lightwave. This effect does not pose a paradox in optics. The analog of time dilation is the increase in irradiance experienced by a lightwave as it propagates through a pure dichroic device.