Gene Heskett wrote: > I've never heard of a massless photon,
That is unfortunate as it should be common knowledge by now. > and they do exert a push on the surface they are reflected from, […] Photons exert a force on surfaces because they carry *momentum* or, as it had been understood in terminology that is obsolete now, a non-zero “*relativistic* mass” (that had been distinguished from “rest mass”). <https://en.wikipedia.org/wiki/Mass#Mass_in_relativity> <https://en.wikipedia.org/wiki/Mass_in_special_relativity#Relativistic_mass> F'up2 sci.physics.relativity -- PointedEars Twitter: @PointedEars2 Please do not cc me. / Bitte keine Kopien per E-Mail. -- https://mail.python.org/mailman/listinfo/python-list
