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I realise that time perception can change but why does time in the physical sense pass at the fixed rate it does (1 second per second)? What governs that rate? Could time pass at a different rate in a different universe with different governing rules (maybe 1000s of times faster) such that light travels faster relative to its speed in our universe but the time perception within that universe being the same as in ours?

Deckie
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    It is possible for a question to simply be nonsense – hft Jun 03 '22 at 22:26
  • You might be referring to the speed at which human beings perceive reality. In which case you may want to research the concept of Critical Flicker Fusion Frequency – RC_23 Jun 03 '22 at 23:04
  • In a comment on an answer below, you talked about "a theoretical different universe...where we could perceive the different rate of time looking into it from our universe." In science, the word "theory" really is another way to say "explanation." What phenomenon that we can observe today would be explained by the existence of that other universe? If there is none, then it's more of a fantasy universe. Not that that's a Bad Thing. I'm just saying that you shouldn't call it "theoretical" if it doesn't explain something that's real. Maybe call it "hypothetical" instead. – Solomon Slow Jun 04 '22 at 01:15
  • Related: https://physics.stackexchange.com/q/291316/123208 – PM 2Ring Jun 04 '22 at 03:12
  • Possible duplicates: https://physics.stackexchange.com/q/52048/2451 and links therein. – Qmechanic Jun 04 '22 at 03:26
  • I don’t agree, I think it could be possible for time to pass at different rates in different universes with different physical constants. As I said below, the difference could only be seen when observed from outside the universe, relative to your own universe. The rate would always appear to be the same when experienced within those universes. It’s no more of a fantasy than Branes and Bubbles within the Multiverse, how are they observed? Reading the responses, I think the answer is beyond the realms of natural physics. – Deckie Jun 05 '22 at 11:45

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Time passing at any rate other than 1 second per second is a logical impossibility (not just a physical impossibility).

A second is currently defined as "$9192631770$ cycles of Cs-133 transition". To say something like "time is passing at 0.8 seconds per second" would be like saying for every $10$ cycles that have occurred, $8$ cycles have occurred."

such that light travels faster relative to its speed in our universe but the time perception within that universe being the same as in ours?

Time "perception" is not a universal physical quantity, but rather exists only in the head of observers and is governed by the time scale on which various biological processes operate (e.g. the time it takes for neurons to transmit signals to one another)

Señor O
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  • Thanks Señor O. If time passed at a different rate than 1 second per second then the cycles of Cs-133 would also be affected and we wouldn’t know the difference. It’s only noticeable with respect to a theoretical different universe with different governing rules where we could perceive the different rate of time looking into it from our universe. We would observe light travelling much faster or slower in that universe but yes, in the head of observers within that universe, time perception would be the exactly same as in ours. – Deckie Jun 03 '22 at 21:28
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    @Deckie "If time passed at a different rate than..." This has already been addressed in the answer where the answered stated: "Time passing at any rate other than 1 second per second is a logical impossibility..." – hft Jun 03 '22 at 22:22
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    @Deckie The questions you are asking do not make sense. It's like asking "what is the square root of birthday cake." It just doesn't make sense. – hft Jun 03 '22 at 22:23
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The question as formulated here does not quite make sense. Time, like any other value, can only be defined relative to something else- similarly to how it wouldn't make sense to ask why space is distributed at the scale of 1 meter per meter.

However, the second part of your question is sensible to ask. There is nothing in physics as we understand it now to prohibit us from imagining a different value of c- maybe 2.99 x 10^9 m/s rather than 2.99 x 10^8. This is because c, being a velocity, relates the passage of time to an interval of space, making it a useful quantity to talk about without having to refer to some other value it relates to.

Of course, we have to keep in mind that this wouldn't change the "speed" at which time passes, exactly, but rather change the value of other quantities relative to some arbitrary interval of time.

Leo
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  • Thanks Leo, please see my comments below (it’s about time relative to that in a theoretical different universe). I was talking about the speed of light possibly travelling faster in a different universe due to its different rules governing the passage of time, not those governing rules affecting its value of c as a constant. Or are the two inextricably linked somehow? Is c fixed to the rate time passes or the other way round? – Deckie Jun 03 '22 at 21:39
  • Changing the value of $c$ does not change the isomorphism class of the Minkowski metric, so how can it have physical consequences? – WillO Jun 03 '22 at 21:52
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    Yes, it is entirely possible to imagine a different universe with a value of c that is larger relative to our value. Although I would be careful about saying that "the passage of time" governs the value of c. In special relativity, it would make more sense to say that the passage of time for observer A relative to observer B is DEFINED by c. The relativity of time passage is a consequence of the fact that the speed of light is constant for all observers. So you can think of time's "speed" as being defined by c rather than the other way around. – Leo Jun 03 '22 at 21:53
  • I mentioned c only as a governing rule for the rate that time passes, rather than just imagining a different universe with a different value of c. If that’s true as you say, then that’s the answer I was after - the rate at which time passes in any universe is governed by it’s fixed value of c. Of course the value can only be seen to vary when observed from outside that universe, relative to your own universe. – Deckie Jun 03 '22 at 22:05