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Progression of time & entropy

  1. Dec 11, 2014 #1
    The directionality of time seems to be linked to the process of increasing disorder.

    Is the 'passage' of time similarly linked?

    If so, it would seem that the passage of time would generally slow down as the universe cools. And perhaps time should pass more slowly in cooler regions of the cosmos; and pass more quickly during times of rapid expansion.

    And, if true, could we even experience or measure it since our senses and instruments would be in sync with what we were trying to measure....unless we were looking into deep space....
  2. jcsd
  3. Dec 11, 2014 #2


    Staff: Mentor

    More precisely, this is one of several possible "arrows of time", the thermodynamic one. There is also a cosmological arrow (the "future" is the direction in which the universe is expanding) and the memory arrow (the "past" is the direction of time in which we can remember events, so the "future" is the other one). There are arguments for why two or even all three of these arrows must point in the same direction, but I don't think the question is settled.

    No, assuming that by "passage" you mean the "rate" at which time passes. The passage of time can be measured by periodic processes that are reversible and involve no entropy change, so there is no way to link the "rate of time flow" to entropy.
  4. Dec 13, 2014 #3
    Surely something must be changing to measure time. The clock must increment or the observer must accumulate memories of the past- these processes would involve entropy?
  5. Dec 13, 2014 #4

    Doug Huffman

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    Cause and effect are the arrow of time.
  6. Dec 13, 2014 #5


    Staff: Mentor

    Good point. The recording of the passage of time does require some entropy increase. However, the periodicity of the process being recorded is not affected by the increase in entropy. So the "tick rate" of the clock would not change as entropy increases. So this inference in the OP...

    ...is not correct.
  7. Dec 13, 2014 #6
    What periodic process (other than a perpetual motion machine) involves no transfer of energy? (ie entropy change)
  8. Dec 13, 2014 #7


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    Two clocks may keep the same time even though their mechanisms do different amounts of work in different ways ( steam vs wind-power say ).
  9. Dec 13, 2014 #8
    gravity; (coordinate acceleration) and certainly requires spacetime.

    I'd say Doug has it most "right" if we're to paint a geometric property as something of a "passing". It's via that "odd" geometric property that the properties of physical "entities" can "play out"....tick tick tick
    Last edited: Dec 13, 2014
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