Do photons collide with each other like any other massive object?

[Ahmed Abdullah]

If they do:
-Do the collisions obey newton's law of motion.
If they don't, why?
What is the difference between a real particle and photon ?
-We know that they both got mass ( photons have relativistic mass E/c^2).
What is the significance of this mass? What does it imply?

Any help will be highly appreciated. Thx

[pam]

1. Photons obey the laws of relativistic quantum field theory, including photon-photon scattering.
2. The photon is as real as any other particle, but has zero mass.
3. Photons do not "have relativistic mass E/c^2". That is an archiac notion, inappropriate in relativistic quantum field theory.
4. That mass has no significance. Its only implication is confusion.

[Ahmed Abdullah]

so it's possible that two electron collided and bounched off......

[Ahmed Abdullah]

by the way what do you mean by the word "other particle"? What is a particle?

[jtbell]

"Photon collisions" have been discussed in a recent thread here:

http://www.physicsforums.com/showthread.php?t=219619

Photons are about as non-Newtonian as one can imagine. After all, they originated in quantum theory, and are fully described only in relativistic quantum field theory.

[faen]

A collision on a micro perspective are just forces bouncing eachother off. I dont think photons have any such forces which can make them bounce, otherwise it would be easily observed by letting two light rays cross eachother. Hence they only act like a superposition of waves when in the same space. Also according to pauli exclusion principles, there's no limit to how many photons may occupy the same state.

[jtbell]

Photons can interact with each other via a process that involves virtual electrons and positrons. I included a diagram of it in this post (http://www.physicsforums.com/showpost.php?p=1634625&postcount=8) in the thread that I referred to earlier. This process has a very small cross-section (probability) and is difficult to observe.