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

Main Question or Discussion Point

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
 
Last edited:

Answers and Replies

pam
455
1
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.
 
so it's possible that two electron collided and bounched off......
 
by the way what do you mean by the word "other particle"? What is a particle?
 
jtbell
Mentor
15,398
3,183
"Photon collisions" have been discussed in a recent thread here:

https://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.
 
140
0
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
Mentor
15,398
3,183
Photons can interact with each other via a process that involves virtual electrons and positrons. I included a diagram of it in this post in the thread that I referred to earlier. This process has a very small cross-section (probability) and is difficult to observe.
 

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