We know what time is - it is change. If photons pass through then time exists. But the original question was fair. It's an interesting thought - a place without time. It's strange. Think about the fact that there is no time before the "big bang" - as it supposedly created this universe and all of it's dimensions, so there could be no time before that. But if there is no time before the big bang, then how did the big bang occur? It required time to occur - and a cause - which implies time (change always does). But if time existed before it, then the "big bang" occurred within a larger universe that preexisted. It's an interesting thought and paradox. If the Universe didn't exist before it, then how did it exist to make the Universe.
I have heard many prominent physicists say we don't really know what time is. Is it an emergent property of the Universe or something that flows? Is change simply something that happens within time, or time itself? This is actually a fairly fundamental question about the nature of time, and one we cannot actually answer. If I am wrong please school me. I might like it .
Well, it's a bit late for me...but I will provide food for thought. Time is not a dimension. It is a result of dimensions. In simplest terms it is change - or at least the ability of change (static systems can exist where time does even if they do not change). Dimensionality is thought to be required (I disagree personally - but that is a different matter) because distance is thought to be required for change to happen. We know that change is a definite indicator of time. But, lack of change does not mean there is no time. Make sense? And yes, a full definition of time is speculative, but the *possibility* of change within a system is required. So in a reference frame where there is true absolute zero - time does not exist (within that reference frame...it may outside of it). That is the best I can do right now - and apologies if it is not adequate. Does that help? EDIT: BTW - does time flow? I don't think anyone knows that, but since it can change relatively from one reference to another - maybe (me just guessing there - I am sure there are others with more insight)
In the other post you said time is change, which seems to be another way of saying it is an emergent property. Here you seem to say that change occurs within time, that time is more of a back drop or a real thing, not just the current state of change. I think it kind of has to be one or the other, but I could not say which.
If between two points in time, every particle in the universe occupies precisely the same state and position, then can those points in time be considered distinct?
Yeah - I saw that. I got loose. And I was tired. And in that last post I wandered. Strictly speaking, time does not equate to change. But it's so close I speak that way and get sloppy. Change is an indicator of time passing. But, all a system has to posses is the ability to change for time to exist. I can't really think of such a system (capable of change but totally static), because at the molecular level if everything is static you are at 0 K and there is no time passing. Keep in mind I am only parroting a description of time I was taught. And it is not the only one. Time can also be described as a consequence of dimentionality. The moment you are in a universe with "locations" (i.e. dimension) time exists because change is possible. In that case, time continues to exist even at 0 K which I am not sure I go for. Another description of time is "change over distance" - which I find kinda simplistic. But all of these involve "change" or the ability to change - so I think that is pretty standard. So sometimes I just think time = change. And you know - it actually might - because I can't think of a truly static system capable of change.
We know what time is - it is change. If photons pass through then time exists. But the original question was fair. It's an interesting thought - a place without time. Time exists whether or no photon's pass through an area. Time is the measurable distance between two points that an energetic bodies travels based upon that energetic bodies interaction with the medium that it is contained within. Even a place such as the "Really Big Hole In The Universe" that does not register like normal matter time still exists across the Hole because the energetic bodies surrounding the Hole can be measured from one point on one side of the Hole to the other side of the Hole without any energetic bodies in the Hole itself needing to be present in order to measure it. Strictly speaking, time does not equate to change. But it's so close I speak that way and get sloppy. Time does equate to change - Even though there might not be matter within the Hole that is measurable the energetic bodies on the perimeter of the Hole itself does in fact move along a timeline thus bringing about a state of change for the Hole itself as those energetic bodies will define the perimeter of the Hole that although it might be timeless on the interior the bodies on its perimeter actually define the Hole's time. Maybe the Hole is actually the space that exists on the outside of our own Universe where we would look out of our Universe from one side across the Void into another Universe on the other side of the Void.
It constitutes a non-cyclic time loop (in theory). In theory there are only so many combinations available. So it is possible (however improbable) for that to happen (though I fail to see how really since our Universe is expanding and all that). But since what led up to the two identical states was different, they would quickly diverge. EDIT: You can kinda draw this on a piece of paper. I think it would feel like Deja Vu. The cockroach theory. Those little critters reproduce at an amazing rate. However, there are only so many genetic combinations. Thus, at some point in time genetically identical roaches have existed. SO the next question was (and I have never seen an answer), has the same happened with humans (outside of twins et al.). It's a calculation that can be done - but I have not seen it done.
That's not what all physicists think (or most). The system need not change for time to exist. It only needs the ability to change. A system that is fully static but has location has the aspect of time. Though - I can't fathom such a situation. But Purplebudda has me thinking (even though this (time theory) is not my specialty). EDIT: This thread has moved a bit too "theoretical" for me. Nice to think about - but takes too much brain time. I think I will stick with planets - lol