Photon in the box is very poorly written  Please   a delete  b correct in order to contain a correct explanation of what is going on  The correct explanation of the photon in a box issue is that the trajectory of the photon inside the box gets slightly curved in the gravitational field such that there is a vertical component of the photon momentum ptangentialpsintheta where pEc is the momentum and theta is a very small angle At each collision with the vertical walls of the box the photon transmits a downward force dpdptangentialdt to the box that can be misconstrued as an increase of mass equal to dpg where g is the gravitational constant Please remove any misleading references to m  Ec Such ridiculous stuff can only further the misconception that the photon has nonzero mass that can be measured  Thank you