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  1. Aug 13, 2004 #1


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    We speak of time quite frequently in science.

    What is time? Anyone have any idea?
  2. jcsd
  3. Aug 13, 2004 #2
    According to modern physics, it is a relativistic phenomenon. In other words, whether or not you perceive time depends upon your point of view.
  4. Aug 13, 2004 #3
    I believe this question belongs more to the Special & General Relativity forums, you will find some interesting discusions about it there.

    In any case, indeed it seems that the passage of time is just a perception due to the perspective we see the universe from.
    Time is relativistic so it's a kind of perspective which unfolds more or less depending on our velocity relative to the other material things in the universe.

    It's like when you watch from the front at 2 cars driving behind eachother, you see them at the same place (at least if you look with only one open eye to neglect the stroboscopic effect for depht perception), yet if you move sideways you can perceive that there is some distance between them.

    This strongly suggests that what we call past and future "already exist" if we consider the issue free from the limitations of our perception abilities (as the time interval we may measure between 2 events is just depending on the perspective we look from).
    Wheter past and future are unique (uncertain but with no freewill) or not (many-worlds theory) is a deep open debate.

    And by the way, it's still somehow comprehensible what time may mean for material objects, but I still didn't hear an understandable reasoning of "what time may be" for radiation ("travelling" at the speed of light relative to any material observers regardless of their motion). Time flow is expected to be frozen, yet points distant from eachother in spacetime are connected (without any "time interval" between them).
    I have 2 threads posted in Relativity to ask for some light about this puzzle, I'm just an afficionado ........
  5. Aug 14, 2004 #4


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    another topic already going with this exact same subject matter...
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