Gamma photon wavelength: Is there a limit?

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Discussion Overview

The discussion revolves around the limits of photon energy, particularly in the context of gamma photons and their wavelengths. Participants explore theoretical limits, the implications of observer-dependent energy measurements, and the distinctions between gamma rays and x-rays.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants inquire whether there is a known limit to the energy of a photon, referencing pair production thresholds and cosmic photon energies.
  • Others argue that, according to current physics, a maximal energy limit for photons is not feasible due to relativistic effects and observer perspectives.
  • One participant expresses confusion regarding the relevance of wavelength to energy, noting the proportional relationship and the origins of gamma rays versus x-rays.
  • It is mentioned that the velocity of photons remains constant at the speed of light, while frequency and energy are observer-dependent.
  • Questions arise about whether the variations in observed energy are solely due to frequency shifts from different effects, such as gravitational or Doppler shifts.
  • A later reply specifies that the example discussed pertains to the Doppler effect.
  • Participants acknowledge the constant nature of photon velocity while recognizing that energy is variable based on the observer's frame of reference.

Areas of Agreement / Disagreement

Participants generally agree that the energy of photons can vary depending on the observer, but there is no consensus on whether a theoretical limit exists for photon energy.

Contextual Notes

Discussions include assumptions about observer perspectives and the implications of relativistic effects on energy measurements, but these remain unresolved.

jerromyjon
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Is there any known limit to the energy of a photon? I've seen a reference to pair production in the highest bracket over 1.02 MeV and I've seen references to energies from cosmic sources in the TeV range which aren't very well understood but is there any theoretical limit?
 
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At least with current physics, such a limit is impossible. Imagine a photon would have a "maximal energy" in our lab frame. Then another observer, moving in the opposite direction, would observe a higher than maximal energy.
 
Thank you for your reply! I don't see how that makes a difference though, observation doesn't affect its maximal velocity. I am trying to grasp wavelength relevance which is exactly proportional to energy if I am not mistaken. I've read that the wavelength ranges overlap to some degree but generally gamma rays originate in the nucleus of atoms and x-rays originate from electrons in the shell. The wavelengths are roughly the scale of an atom and shorter for gamma, longer for hard x-rays. I'm just trying to get it into a reasonable perspective...;)
 
The velocity is always the speed of light.
The frequency and therefore the energy (yes, they are exactly proportional) depends on the observer.

jerromyjon said:
I've read that the wavelength ranges overlap to some degree but generally gamma rays originate in the nucleus of atoms and x-rays originate from electrons in the shell.
Well that is just a naming convention.
 
Is that exclusively due to frequency shift from gravitational, doppler and cosmological differences or are there other factors?
 
In the setup I described (as an example), just doppler effect.
 
Thank you very much, I get your point. Velocity is a constant because it is the same for all observers, but energy varies with respect to the observer.
 

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