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

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Discussion Overview

The discussion centers on whether photons collide with each other like massive objects, exploring the implications of such interactions within the framework of physics. It touches on concepts from relativistic quantum field theory, the nature of particles, and the significance of mass in this context.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that photons obey the laws of relativistic quantum field theory, including photon-photon scattering.
  • Others argue that photons are real particles but possess zero mass, challenging the notion of "relativistic mass" as outdated and confusing.
  • One participant questions the definition of "other particle" and what constitutes a particle.
  • Another participant notes that collisions at a micro perspective involve forces, but suggests that photons do not exhibit such forces, leading to the idea that they behave as a superposition of waves instead.
  • It is mentioned that photons can interact through processes involving virtual electrons and positrons, although these interactions have a very small probability and are difficult to observe.

Areas of Agreement / Disagreement

Participants express differing views on the nature of photon interactions and the significance of mass, indicating that multiple competing views remain without a consensus.

Contextual Notes

There are unresolved questions regarding the definitions of particles and the implications of mass in the context of photons, as well as the limitations of observing photon interactions.

Ahmed Abdullah
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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
 
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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?
 
"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.
 
A collision on a micro perspective are just forces bouncing each other off. I don't think photons have any such forces which can make them bounce, otherwise it would be easily observed by letting two light rays cross each other. 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.
 
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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