# Time relative to the observer.

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I am not a physicist by any means; I am just any armaturewho has an interest in theoretical physics.

Since time and space are one and the same, would it not be the case that the standard time of the universe would be determined by the rate of expansion of space/time? I do not mean a standard time in an absolute sense;time is relative to the observer, as I understand it. What I mean is for objects in space, which are relatively stationary, or move slow enough that the relative time these objects experience is nearly identical to the relative time experienced by all other nearly stationary objects in space. If I understand correctly, that the speed of the observer (through space/time) relates to how they observe the passage of time, I think this is because when the observer changes their position is space; they are also changing their positionin time? Would this mean time is an actual physical dimension through which we are traveling ever forward, and the rate at which time is moving forward in the universe would be determined by the rate of expansion of space/time? Am Iway off on this?

If this is correct, and the universe is accelerating the rateof space/time expansion, this would mean time is expanding at an increased ratealso….so time would be passing relatively more quickly to an observer? Would thisalso mean that if the rate of space/time expansion has been accelerating at asteady rate, in the distant past, early universe, time would have passed relativelymore slowly. But what would this relative change in the rate of time passagehave on our physical reality. If you could have been an observer at the bigbang, and watched the universe expanding, would you have any perception of thechange in the increasing rate of space/time expansion? Since the universe wouldhave been expanding more slowly, time would have passed more slowly, would thismean that a billion early universe years would pass more slowly than a billionyears at our current rate of expansion?

Edit,

Im just asking in an attempt to understand, But rather than time speeding up due to the increase in the rate of expansion, since the speed of light is constant, would time need to pass more slowly since space is expanding more rapidly? If that is so, then time in the past would have passed more quickly?

Edited by cogito
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• 2 weeks later...

Well it's over my head, but...

As you mentioned, time is relative. If part of the universe is expanding away from you at a certain speed, that will affect the rate at which clocks tick in that area, as observed by you. The solar system for example is not expanding such that things are moving away from each other at a rate approaching c. So time anywhere in the solar system, viewed from anywhere else in the solar system, would not change much over a billion years due to expansion of the universe. It has expanded at most a light hour or whatever it is, in its history. Time as we know it... all clocks on Earth (including natural pre-man ones) should not be different over a billion years due to relativistic velocity of expansion.

Also... relativistic velocity only slows down clocks. At relative rest is their fastest; motion toward or away from a clock will slow it. So if expansion is increasing, time (at the furthest reaches of the universe relative to us) is slowing, not increasing its rate.

A smaller universe in the past should allow for greater density of matter and probably greater gravitational differences, which according to GR would mean slower time in the past (when viewing an area that's in a strong g field from an area with a weaker field).

If the entire universe is expanding, the solar system would have been smaller in the past (as would Earth, the galaxy, everything), and I'm not sure what kind of effect, if any, that would have on time within the solar system, viewed from within the solar system. Also not a physicist!

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