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I was reading The Black Hole War, by Leonard Susskind, when I came across a section describing the moving and relative bending of time. If time is a property of the movement of all matter in relation to one another, would time cease to exist if all movement stopped? Is this absolute zero?

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  • $\begingroup$ In Minkowski space, there is no matter, hence no movement of matter. Do you want to conclude that there is no time (whatever, precisely, you mean by that)? $\endgroup$ – WillO Dec 20 '17 at 21:37
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    $\begingroup$ possible duplicate/opposite of physics.stackexchange.com/q/242709 $\endgroup$ – kpv Dec 20 '17 at 22:37
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    $\begingroup$ Possible duplicate of Can there be motion without the flowing of time? $\endgroup$ – sammy gerbil Dec 21 '17 at 1:38
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    $\begingroup$ The downvotes seem unkind. This is a perfectly reasonable question from anyone who doesn't know GR. $\endgroup$ – John Rennie Dec 21 '17 at 8:45
  • $\begingroup$ @JohnRennie: I did not downvote, but in view of the fact that SR provides the obvious counterexample, you'd have not-know a lot more than GR for this question to be reasonable. $\endgroup$ – WillO Dec 21 '17 at 21:02
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The question is a classical one in philosophy of time, whether time is only due to events happening (the reductionist view) or independently of events (the Platonist view).

In modern physics (or at least general relativity) the answer is presumably close to the Platonist view, in that space-time is regarded as a primary "thing". There are points of space-time forming a manifold regardless of the presence of matter or its changes. Time is after all just another direction in this framework.

At absolute zero most but not all motion is gone: everything is at its ground state, but there are processes like quantum tunnelling that can happen anyway: some change is possible.

The real time-freeze would be moving at the speed of light: no change seems to be possible for a system moving along a null-geodesic (until it hits something).

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If time is a property of the movement of all matter in relation to one another, would time cease to exist if all movement stopped?

Consider the Schwarzschild (exterior) solution to Einstein's field equations.

(1) there is no matter anywhere, anywhen so literally nothing is moving.

(2) the geometry is static (independent of time)

Yet, in this spacetime, time exists and there is a causal structure, i.e., time-like, light-like, and space-like geodesics.

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