🚀 go-pugleaf

In article <l81lk0INNdu4@pollux.usc.edu> srobiner@pollux.usc.edu (Steven Robiner) writes:
>I think I've heard that if a photon hits an electron, it
>is absorbed (assuming it's off the right energy level), and
>the electron will recoil a bit, correct?

	No.  Free electron/photon collisions can only conserve energy
and momentum in a kind of elastic collision (Compton scattering).
A bound electron can have an 'energy level', but it's more a collision
between a photon and an ATOM in that case.  The atom recoils, not
the individual electron (which is constrained so that it is not
free to recoil).

>But what happens when a photon hits another photon?  Do they
>bounce off each other, or pass right through each other?

	They pass through each other, unless some material substance
is involved (which can complicate the matter by having a nonlinear
response...optical switches can be made that work this way).
That's what one expects; the light wave is an electric disturbance,
and will apply force on a charged particle (electron), but NOT
on an uncharged particle (like a photon).

	John Whitmore