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2 Dimensions

  1. Jan 2, 2014 #1
    Does a photon, or any particle that travels at c, believe the universe to be 2 dimensional?
     
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  3. Jan 2, 2014 #2

    ShayanJ

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    At first we should know exactly what you mean by a photon's belief!!!
    And next,I know how such questions come up.You're thinking about something and at the middle of that you think you have understood something else which is also important and you start thinking about that and drawing conclusions from it.So I think if you tell us the line of thought which led you to this question,we can help you better.
     
  4. Jan 2, 2014 #3
    Lorentz contraction at c would be infinite right? So the photon sees infinite contraction in it's direction of travel?

    Forgive me but i am a middle aged man intrigued by physics with no background at all.
     
  5. Jan 2, 2014 #4

    ZapperZ

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  6. Jan 2, 2014 #5

    ShayanJ

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    No,its OK.Relativity is confusing when you're first learning it and such questions are natural to come up.
    The point is that,you shouldn't struggle that much with such confusing things in physics.At least not until you're really good at physics.
    Let's think about that more carefully.Anything which travels at c,travels at c w.r.t. to everything else and is going to continue to do that.So anything else for it should be length contracted to zero and also everything else should stop evolving because of the time dilation.So it looks like that time stops and because the space is contracted to zero length in its direction of travel,it has no space to move!So it can't move!
    But its not that bad.because nothing moves in its own reference frame and we have as yet no way of experimenting in a frame moving at c so there is no problem here.But yes,its puzzling,confusing and maybe non-sense!
    The point is that the speed of light is a singularity for us,one of the edges of science,something we don't understand fully yet.So we still should wait for other things that help us understand it better.Although I think some people would argue its OK.I can't say I oppose them.Let's just wait till we know more physics and know the physics better!

    EDIT:Ooops...thanks Zz, looks like I fell in the same trap!I should keep reminding that to myself because I remember understanding it once!!!
     
  7. Jan 2, 2014 #6
    Which brings me to my next question Shyan. Because a photon will not experience time, or direction of travel, it simply cannot exist until it is absorbed, or am i completely missing something?

    Can you see how i arrived at this? It doesn't travel though space because of lorentz contraction, it dosent experience time, and it is guaranteed to be absorbed because everything in the universe is moving and so sooner or later it will be absorbed. So it exists for eternity, and doesn't exist at all?

    Am i really missing something?
     
  8. Jan 2, 2014 #7

    ZapperZ

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    You missed the link I gave you to the FAQ that explains the fault in your logic! You are applying concepts of physics that are not valid in the photon's reference frame! Thus, saying "photon will not experience time or direction of travel" is not a valid statement!

    We cannot try to explain to you the faulty concepts of physics that you are using. That's like asking us to explain why unicorns only fly at night!

    Zz.
     
  9. Jan 2, 2014 #8
    Zapper, I understand reference frames and the paradoxes that arise. But i cannot comprehend some things and came here to see if you (or anyone else) could explain. Pointing me to a FAQ that i can read anywhere is not really in the spirit of a forum.

    "The faulty concepts of physics you are using" I hope that statement makes you feel good about the completely sound and bulletproof concepts you employ, that you seem to be unable or unwilling to explain.
     
  10. Jan 2, 2014 #9

    PAllen

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    Pointing to an FAQ for a question asked hundreds of times is exactly what this or any sensible forum should be doing. Now, if you have a further question after reading the FAQ, that is fine; but ask it in such a way as to show you've attempted to understand the FAQ.

    The FAQ explains extremely simply that 'rest frame of a photon' is a logical contradiction in SR, so asking about what it would be like is exactly equivalent to asking what would arithmetic be like if 1 = 0 (you could prove any statement and its contradiction).

    If you ask in terms of a limiting process, then you find no problems:

    - However close to c A moves relative to B, light still moves at c relative to A; the universe has 3 spatial and 1 time dimension.

    Thus there is no physically meaningful limiting process that leads to loss of a spatial dimension or a time dimension.
     
  11. Jan 2, 2014 #10

    ZapperZ

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    Your are applying the physics of Special Relativity. That physics has an implicit assumption that the speed of light is invariant in all reference frame! Yet, you are applying that physics in a frame in which you are at rest with the light!!!! In this frame, the assumption and foundation of Special Relativity are no longer valid, yet you continue to USE those very same equations and conclusions!

    You don't need to know physics to be able to see why you are using something where it wasn't meant to be used!

    Zz.
     
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