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 p_tangential=p*sin(theta) where p=E/c 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 dp=dp_tangential/dt to the box that can be (mis)construed as an increase of mass equal to dp/g where g is the gravitational constant. Please remove any misleading references to Δm = E/c². Such ridiculous stuff can only further the misconception that the photon has non-zero mass that can be measured.

Thank you