Yes. Do you see a problem? — Mongrel

That would seem to be the same problem afflicting the idea of displacing the whole of space. You can shift a house 100 feet to the North. Can you move the whole of space in the same direction? What would such a hypothetical displacement be relative to?

That would seem to be the same problem afflicting the idea of displacing the whole of space. You can shift a house 100 feet to the North. Can you move the whole of space in the same direction? What would such a hypothetical displacement be relative to? — Pierre-Normand

There is no need for God to wind the clock back, because there is no clock. The state of the universe that correlates with the clock position of 4hrs ago, is still there.

This experiment demonstrates what god sees:

https://medium.com/the-physics-arxiv-blog/quantum-experiment-shows-how-time-emerges-from-entanglement-d5d3dc850933

It's not "undetectable to us." It's undetectable even in principle. Then apply Leibniz's Law. — Mongrel

If God moves time back, then God knows that time is moved back. If God knows this, then it is in principle "detectable". We need to allow for the possibility of things which are undetectable to us, but are detectable by means which are not available to us. This would not negate the absoluteness of time, because we allow for absolutes within different categories, just like different infinities. So time would be absolute, but not the absolute absolute because we've allowed God into this scenario, and God takes that place.

That would seem to be the same problem afflicting the idea of displacing the whole of space. You can shift a house 100 feet to the North. Can you move the whole of space in the same direction? What would the displacement that would have hypothetically occurred be relative to? — Pierre-Normand

Right. Leibniz shows the problem of absolute space by imagining the universe is finite and sitting in a void. Assuming absolute space, the void is empty space waiting to contain something. We might imagine xyz axes expanding out from the center of the universe and continuing on beyond it.

It's only when we imagine the universe moving within the void that the logic of it breaks down. We have proposed motion that even in principle can't be observed.

Einstein also takes us to a void in special relativity. Again, we're looking at the meaninglessness of trying to travel around in a void.

Trying to adapt the thought experiment to address time is a little confusing to me.

I don't think God would be able to detect the change either. Think about the question Pierre asked: what is the change relative to?

Right. Leibniz shows the problem of absolute space by imagining the universe is finite and sitting in a void. — Mongrel

Which is not what the universe is like. It's infinite.

Trying to adapt the thought experiment to address time is a little confusing to me. — Mongrel

Can't you ask essentially the same question about time? Anything that occurs (e.g. the construction of a house) could have occurred four years earlier (or later). But could everything that is occurring (and occurred, and will occur) in the whole universe occur four years earlier? Relative to what event would everything have occurred four years earlier?

Can't you ask essentially the same question about time? Anything that occurs (e.g. the construction of a house) could have occurred four years earlier (or later). But could everything that is occurring (and occurred, and will occur) in the whole universe occur four years earlier? Relative to what event would everything have occurred four years earlier? — Pierre-Normand

The entropy of the visible universe for example.

No. Totally legit. Complete sense. [Backs away nervously, feeling for the door...]

The entropy of the visible universe for example. — tom

Well, I was assuming all the micro-physical "events" to be shifted as well, not just the macroscopic ones. Since the entropy of a physical system supervenes on its micro-physical state, then the entropy of all the systems (including local cosmic background radiation) would be shifted back in time by the same amount.

I don't think God would be able to detect the change either. Think about the question Pierre asked: what is the change relative to? — Mongrel

The change is relative to God. That's the issue, the proposition assumes a God to carry out this act, so we cannot just dismiss God now, to claim that the change is not relative to anything. Now God is understood as an immaterial being, so the change is relative to an immaterial existence. The change is undetectable to us, because we gauge time by judging material changes, but now we've assumed an immaterial existence, and this immaterial existence must have some other means of gauging time.

Can't you ask essentially the same question about time? Anything that occurs (e.g. the construction of a house) could have occurred four years earlier (or later). But could everything that is occurring (and occurred, and will occur) in the whole universe occur four years earlier? Relative to what event would everything have occurred four years earlier? — Pierre-Normand

The possibility that time and space are limitless is confusing me. But is that a problem? Can the thought experiment just say that for every E, E happens 4 hours earlier? And not address whether time is finite or infinite?

this immaterial existence must have some other means of gauging time. — Metaphysician Undercover

It's a reductio ad absurdum argument. God's decision to move the universe is not a premise, it's the object of analysis. Does it make sense for God to move the universe?

Which is not what the universe is like. It's infinite — tom

Could be.

The possibility that time and space are limitless is confusing me. But is that a problem? Can the thought experiment just say that for every E, E happens 4 hours earlier? And not address whether time is finite or infinite? — Mongrel

The same question arises. Relative to what is everything happening four hours earlier? You have to imagine some undetectable framework of time (rather in the way one might want to picture empty space, metaphorically, as an empty stage) relative to which events are dated extrinsically. But if that's the case, then there would have occurred a shift in the time of occurrence of all the empirical events, all right. But time itself would not have shifted since it would have been externalized, as it were, to this inobservable framework.

Let us get back to the space analogy. We could imagine "space itself" being externalized in a manner somewhat analogous to the luminiferous aether of pre-relativistic physics; with the proviso that such an aether would be physically undetectable in principle. Can then everything in the universe be conceivably shifted 100 feet in one determinate direction? This can be conceived. But you still would not have shifted space itself, since on that account, space would have been externalized. It has been identified with the absolute spatial "positions" of the aether "stage". And this aether still would not have moved. If you were to imagine that the aether (space itself) also moved, then that must be a movement relative to some external spatial framework. You need another aether to identify "space itself" with. You are led to an infinite regress.

It's a reductio ad absurdum argument. God's decision to move the universe is not a premise, it's the object of analysis. Does it make sense for God to move the universe? — Mongrel

If you believe in God, yes. If you do not, no. God is an immaterial existence, so if time is relative to God, then a change in time does not necessitate a change in material existence. But if you do not believe in God, then there cannot be a change in time without a change in material existence.

Well, I was assuming all the micro-physical "events" to be shifted as well, not just the macroscopic ones. Since the entropy of a physical system supervenes on its micro-physical state, then the entropy of all the systems (including local cosmic background radiation) would be shifted back in time by the same amount. — Pierre-Normand

You asked what time could be reversed relative to. Total entropy is one measure.

Anyway, not even God cand wind back something that doesn't exist. All she needs to do to observe the state of the universe that correlates with my clock 4hrs ago, is index the space-time.

You asked what time could be reversed relative to. — tom

Maybe someone else, not me. I didn't touch on the issue of the arrow of time. I was only considering the intelligibility of the idea of shifting the temporal scale (or all events) four hours in the past (or in the future), in analogy with the idea of a uniform translation of space itself.

Maybe someone else, not me. I didn't touch on the issue of the arrow of time. I was only considering the intelligibility of the idea of shifting the temporal scale (or all events) four hours in the past (or in the future), in analogy with the idea of a uniform translation of space itself. — Pierre-Normand

If it's a "scale" it just needs renaming.

That would be the word of God? Could we trust God's word, that it really happened?

Meh. Put it in a lab. What do you do?

You use a clock.

I think you're right. I've developed a head cold.. need to come back to it when I can see straight. :)

Did we agree or disagree that Leibniz's argument for relative space works for relative time?

Did we agree or disagree that Leibniz's argument for relative space works for relative time? — Mongrel

Yes, if what is being denied under the label "relative time" is the intelligibility of the idea of an absolute positioning of events in time, then the argument against the idea of an absolute positioning of events in space works just the same for time, it seems to me.

Cool. So there could be no passage of time in a void. Picking a point in time is actually picking an event. The assignment of a temporal point says something about how our event is related to other events. Is that about all we can glean from Leibniz?

Cool. So there could be no passage of time in a void. Picking a point in time is actually picking an event. The assignment of a temporal point says something about how our event is related to other events. Is that about all we can glean from Leibniz? — Mongrel

I don't know; I'm not familiar enough with Leibniz's metaphysics.

I wouldn't go as far as saying that picking a point in time is actually picking an event. (I assume you mean "event" to refer to something more substantive than what physicists call events: i.e. mere space-time points). But it does require there being a substantive framework (e.g. an actual set or rulers and clocks) relative to which temporal (as well as spatial) locations are defined.

A clock is a continuous sequence of events (I didn't mean physics events, just regular ones).

If you put a clock in a void, you will have injected time into it. True?