Photon interaction with gravity.

MathematicalPhysicist

I read this week in Schutz's description of Pound-Rebka experiment, which demonstrate that a photon also interacts with gravity, i.e measuring its redshift.

My question, is more from particle physics, I mean a photon is the interaction carrier of EM, its chargeless and massles, so how can it be affected by gravity which acts usually on objects which have mass?

You can move this thread if it's not the right place.

jtbell

http://www.physicsforums.com/showthread.php?t=511173

Passionflower

Stationary clocks do not run at the same rate at different heights so then obviously measured frequencies are different as well. So how can we say it is instead the photons that change?