What causes a single photon to propagate in an infinite spacetime?

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SUMMARY

This discussion centers on the propagation of a single photon in an infinite spacetime devoid of mass and curvature. It concludes that while the motivation for the photon’s propagation remains unanswerable, the vacuum energy does not influence its trajectory in a gravity-free universe. The photon’s state, particularly as a momentum eigenstate, results in its position being distributed across the universe. The uncertainty principle allows for energy fluctuations, leading to the creation of particle-antiparticle pairs that can result in gamma photon emissions.

PREREQUISITES
  • Understanding of quantum mechanics and the uncertainty principle
  • Familiarity with concepts of spacetime and vacuum energy
  • Knowledge of photon behavior and properties in physics
  • Basic grasp of particle-antiparticle pair production
NEXT STEPS
  • Research the implications of the uncertainty principle in quantum mechanics
  • Explore the role of vacuum energy in quantum field theory
  • Study the behavior of photons in various spacetime geometries
  • Investigate particle-antiparticle pair production and annihilation processes
USEFUL FOR

Physicists, quantum mechanics students, and researchers interested in the behavior of photons and the implications of vacuum energy in theoretical physics.

Loren Booda
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Imagine a massless, classically zero curvature, infinite spacetime in which propagates a single actual photon. What eventually motivated this photon to propagate, and does its trajectory or energy vary due to the spacetime vacuum energy?
 
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It's impossible to answer the first question. I believe the answer to the second is that the vacuum energy would be completely irrelevant in a universe without gravity. If the photon actually has a trajectory depends on the state it's in. If it's a momentum eigenstate, its position is smeared out over the entire universe.
 
Given an infinite time, we can use the uncertainty principle to argue that energy is borrowed from the vacuum, a particle-antiparticle pair for example is created and the particles then annihilate into 2 gamma photons which travel in opposite directions, instead of going back into the vacuum. Then, if you want, you can ignore one of them (I wonder if this makes sense?). I can't answer the second question.
 

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