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Thread: Photons and time

  1. #1 Photons and time 
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    So we've gone over the theory of relativity (the special) in school this week.
    Was sitting here and looking over my notes when a question popped in to my mind.

    So the premise is that the faster you go the slower "your" time will be. So how will a object like a photon that travels at the speed of light perceive it's own time?

    Does it or doesn't it?

    Regards

    Eric


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  3. #2  
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    For photons time stands still.


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  4. #3 Re: Photons and time 
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    Quote Originally Posted by skogis
    So we've gone over the theory of relativity (the special) in school this week.
    Was sitting here and looking over my notes when a question popped in to my mind.

    So the premise is that the faster you go the slower "your" time will be. So how will a object like a photon that travels at the speed of light perceive it's own time?

    Does it or doesn't it?

    Regards

    Eric
    What special relativity says NOT that "the faster you go the slower "your" time will be".

    What special relativity deals with is the difference in measurements between two separate inertial frames of reference in uniform motion with respect to one another.

    So it says that if you are moving very rapidly with respect to me that I will see your clock as being slow with respect to my clock. Your clock will seem perfectly normal to you. My clock will seem slow to you.

    Similarly your ruler will be short to me and my ruler will be short to your. But your ruler will be perfectly normal to you and mine will be normal for me.
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  5. #4  
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    Yes, thanks for clearing that up *remembers not to post physics questions late at night*, so to me (a photon) your clock would stand still?

    Regards

    Eric
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    As I understand it, photons are subject to the laws of quantum mechanics, and not to the laws of our macro universe. So the laws of physics and time dilation may not apply to them as they would to us.

    Furthermore, photons are travelling at the speed of light, because they are particles of light, so even if they were bits of normal matter subject to the laws of the macro universe, time may stand still.
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  7. #6  
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    Quote Originally Posted by LegalEagle
    As I understand it, photons are subject to the laws of quantum mechanics, and not to the laws of our macro universe. So the laws of physics and time dilation may not apply to them as they would to us.

    Furthermore, photons are travelling at the speed of light, because they are particles of light, so even if they were bits of normal matter subject to the laws of the macro universe, time may stand still.
    Ostensibly ALL particles and objects are subject to ALL laws of physics, including relativity. Similarly all particles and objects are subject to quantum mechanics.

    However, gravity is generally not important with regard to subatomic processes, at least at the usual scales involved. An quantum effects are not important for macroscopic objects, at least under normal circumstances.

    That is fortunate, since the known major theories of physics, general relativity and quentum field theories, are not compatible. There is a lot of ongoing research to attempt to formulate a theory that would incorporate both gravity and quantum processes, but as yet no such theory has been successfully formulated. We do have successful quantum field theories that include special relativity (a major reason for the existence of those theories) but not general relativity.

    Photons are most certainly subject to special relativity. The fact that photons propagate at a fixed speed in all intertial reference frames is one of the two major axioms of special relativity. But you cannot just naively apply the Lorentz transformation to photons since the equations are singular at the speed of light.
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  8. #7  
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    In the twins paradox the twin that went out in space does in fact age less. So his clock did in fact tick slower because he was moving fast. It did not seem slower to him so to him everything else was ticking faster, right, because they aged more?
    Some particles take longer to decay when they are accelerated to relativistic speeds, so to us there clock has indeed slowed. so is it not true that the faster you go the slower you clock actually ticks. You get to the future faster the faster you go?
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  9. #8  
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    if the speed of light is 10. you have 2 objects traveling past each other. each object is traveling 7. accumulatively they will pass each other at 14. but because light can only travel at 10 they will appear to travel slower when in fact they are not. we are getting to caught up in the mechanisms we use to see things. time does not change. it is the most stubborn law in existence.
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