Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gamma photon wavelength: Is there a limit?

  1. Oct 30, 2014 #1
    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?
     
  2. jcsd
  3. Oct 30, 2014 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    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.
     
  4. Oct 30, 2014 #3
    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...;)
     
  5. Oct 30, 2014 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    The velocity is always the speed of light.
    The frequency and therefore the energy (yes, they are exactly proportional) depends on the observer.

    Well that is just a naming convention.
     
  6. Oct 30, 2014 #5
    Is that exclusively due to frequency shift from gravitational, doppler and cosmological differences or are there other factors?
     
  7. Oct 31, 2014 #6

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    In the setup I described (as an example), just doppler effect.
     
  8. Oct 31, 2014 #7
    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Gamma photon wavelength: Is there a limit?
  1. Gamma and photons (Replies: 7)

Loading...