Question about simultaneity..

Discussion in 'Physics & Math' started by Quantum Quack, Sep 19, 2006.

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  1. Quantum Quack Life's a tease... Valued Senior Member

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    We have a star that has been shining for a few millions of years of so and we have two ships traveling at different velocities relative to each other and the star with in this light field emmitted by the said star.
    They are also at differing distances from the star.

    At all times the ships are reflecting the light from the star.

    Is the ongoing moment of continuous reflection simultaneous for both ships as experienced by those ships.

    Thanks in advance for clarifying this issue for me.....
     
    Last edited: Sep 19, 2006
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  3. James R Just this guy, you know? Staff Member

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    What's an "ongoing moment"?
     
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  5. Quantum Quack Life's a tease... Valued Senior Member

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    I am not sure why it is so hard to describe in physics terminology, but maybe if I expand the scenario a little:

    Two ships docked with each other, their hulls are reflecting the light of a near by star. If we assume that a light event has zero duration, that is to say that the time involved in reflecting the light is zero [ light having no rest frame] one could conclude that both ships experience an ongoing moment of reflecting as time passes.
    sorry if this sounds convoluted....

    So, our ships undock and whilst one stays relatively stationary with the star the other accelerates away, at all times continuing to experience that ongoing moment of reflecting.

    The question I want to ask is relatively simple yet for me hard to put in the language needed to be concise.

    As the ships separate is that ongoing moment of reflection sustained as simultaneous?
    I understand that from an observational point of view this would appear not to be the case when observing the reflection of the other ship due to light info delays. However I am not to concerned about what the other observer witnesses [ about the other ship] but more about the actual ongoing zero duration moment of reflecting by both ships.

    Possibly someone would care to show how this question could be asked in a more productive manner?

    For example both ships could be fitted with light sensitive panels that constantly generate a steady electrical current. Is the moment of ongoing generation simultaneous when comparing both ships now at relative velocities. [ assuming no delays in between reflection and electrical generation within the panels.]
     
    Last edited: Sep 20, 2006
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  7. James R Just this guy, you know? Staff Member

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    Light from the star comes in individual photons. At any instant, only some of the photons will be reflecting. Thus, there is no "ongoing moment of reflection". Instead, there are many many "moments of reflection" as different photons are individually reflected.

    By the way, an "event" in physics always has zero duration. A good way to picture an event is to think of it as like taking a photograph of something, which "freezes" things in a particular moment in time. Time itself contains series of events, like photographs strung together to make a film.
     
  8. Quantum Quack Life's a tease... Valued Senior Member

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    Is it appropriate to use the words "event potential" when discussing a photon in transit?
     
  9. James R Just this guy, you know? Staff Member

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    No.

    The presence of a photon at a particular point in space at a particular moment in time is an event the same as any other.
     
  10. Quantum Quack Life's a tease... Valued Senior Member

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