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Do anti-stars absorb photons?

  1. May 31, 2007 #1
    Do antistars absorb photons?

    I read Feynman's Book, "QED - The Strange Theory of Light and Matter", there a while back.

    With reference to Feynman's book, "QED",
    He said,... "Every particle in Nature has an amplitude to move backwards in time, and therefore has an anti-particle."
    So, from this I think an anti-photon would look like a photon, but a photon is traveling forward in time, whereas an anti-photon is like a photon traveling backwards in time.

    Just wondering, althought an antistar may not exist.
    And the CP violation sure does seem to put a spanner in the works for time reversal symmetry...

    If an anti-star did exist, would it be emitting anti-photons.
    As far as I know, an anti-photon is like a photon going backwards in time.
    Therefore, I reckon, from our perspective the anti-matter star, would seem to be absorbing photons.

    If this is so then an anti-star would be a bit similar to a blackhole in the sense that they are not directly visible.
    However a blackhole is different as it is the result of the collapse of regular matter due to its gravity.

    What do you's reckon? When viewed with time moving forward as we experience it, would the antistar seem be absorbing photons?

    I haven't a clue is there any known anti-matter star, or if such a thing as an anti-supernova has ever occurred (like a supernova happening backwards in time). Probably unlikely because of the CP violation.
    Last edited: May 31, 2007
  2. jcsd
  3. May 31, 2007 #2
    The Feynmann statement that antiparticles can be viewed as particles is just an expression of certain mathematical analogy. You can either view antiparticles as antiparticles moving forward in time or as particles moving backwards in time.

    A star made of antimatter will emmit antiparticles, in particullar antiphotons. Since antiphotons are the same particles as photons, the antistar will emmit photons in the usual way.
  4. May 31, 2007 #3


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    Photons do not travel in time. It sounds strange but that is what relativity tells us. As a rough handwaving explanation, you may have heard that as your relative velocity increases the rate at which time 'ticks' on your watch compared to the stationary reference observer decreases. The closer you get to the speed of light (relative to the other observer) the slower it gets by comparison. For light which, obviously, travels at the speed of light this rate goes to zero. Time does not 'tick' at all. So photons don't 'experience' time 'ticking' and hence they don't have a time reversed anti-particle.

    For an explanations of why we don't expect to find anti-stars see https://www.physicsforums.com/showthread.php?t=172131"
    Last edited by a moderator: Apr 22, 2017
  5. Jun 1, 2007 #4


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    No anti-stars, nor anti-photons. They do not exist in this universe. An anti-photon is paradoxical to begin with. Think zero spin.
  6. Jun 4, 2007 #5

    This is a quote from this interesting link about Retrocausality...


    It said that Feynman employed retrocausality to provide a proposed model of the positron, electrons moving backward in time would appear to possess a positive electric charge.

    And then goes on to say, further understanding of antimatter has rendered this model largely obsolete.

    This suggests antistars are not stars going backwards in time from our perspective.

    Any suggestions to what the largest anti-matter object would be?

    Would it be just anti-particles, or would it be anti-hydrogen, or larger anti-atoms, or multiple anti-atom object, or anti-one_kilogram object, or anti-planet,
    or antistar, or anti-galaxy, or anti-cluster, or anti-universe?
    Last edited: Jun 5, 2007
  7. Jun 4, 2007 #6


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    No it doesn't. Anti-matter things such as stars or gas clouds would interact with light exactly as the equivalent matter objects would. They would be indistinguishable from a distance.
  8. Jun 5, 2007 #7
    I meant...

    This suggests antistars are not stars going backwards in time from our perspective.
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