How Can a Star Be Older Than the Universe?

That is we see red-shifts when we observe distant objects. And comparing that to other distance estimates, we see that far away things are more red-shifted. As if they are moving away from us.

When we build cosmological models to explain this, we could choose reference coordinates for time and space in different ways. But if we choose to define time and distance in the usual way then we get a picture in which the distances between all galaxies is increasing with time.

> All you are doing here is disagreeing with the conclusion; you have not offered any refutation of the argument that leads to it. The reason for me saying "the relevant differences must be causally dependent on what form the expansion takes" is that if they were not, then they would not be the sort of differences that could be used to choose between the alternatives. And if they were so dependent, then the mapping from what we observe from here to what would be observed there also has that dependency.

It's circular if we assume the form of the expansion. If the real form influences our measurements, and we use that to figure out what telescopes would show, which lets us calculate the real form, then nothing is circular.

> Actually, Swebs' original claim was pretty much that, as it could accurately be paraphrased as "we have seen, with our telescopes, that, when observed from a different galaxy, the expansion also seems to have originated there." You seem to have put yourself into the position of defending a claim that you do not actually believe in.

No, those are very different statements. "We can tell from here what telescopes would show" could be part of a valid argument. "We need to go there to know" is not necessary.

> There is something very confused here, but I cannot figure out what it is. I can say that my point does not have anything to do with "how our telescopes would differ from a distant galaxy."

I'm talking about the "none of our telescopes have observed the universe from the perspective of a distant galaxy" stuff.

Okay, look, this is clearly not working. If you want to format your argument as a numbered chain of logical statements, I can probably give you a response you'll understand. Otherwise I'm giving up. Big blobs of paragraphs are not conducive to debating whether there "must" be certain assumptions.

Basically, ignoring wormholes and black holes and assuming that spacetime is locally flat everywhere and it's mathematically a manifold, my question is: what's the shape of the (global) universe?

Global as opposed to observable. So we might have a hard time answering that question. How would you be able to distinguish between the (n-dimensional equivalent of) a torus vs a flat infinite space, if you can't see the repetition?

You'd even have a hard time distinguishing a hypersphere from a flat infinite space, if the hypesphere was big enough so that we can't tell it's curvature apart from no curvature.

Or the universe might be weirdly shaped, and we just happen to live in the flat part.

So I guess the question comes down to:

* assuming no edges * assume Copernicus at least for space (we might have a special position in time) * What's the simplest theory about the shape of the global universe that satisfies our observations?

I suspect general relativity toys around with such questions, because I know that they sometimes look at cosmological (toy) models for the whole universe, and not just what's in the light cone of one particular observer.

Because measurements are not assumptions.

If we use assumptions about UEOS/UEIS to figure out what telescopes show, and use that as evidence for UEOS/UEIS, that's a circular argument.

If we use measurements to figure out what telescopes show, without any assumptions about UEOS/UEIS, and then use that as evidence for UEOS/UEIS, that's not a circular argument.

(And obviously there are always some assumptions when being sufficiently pedantic. It's an assumption that the sun still exists, etc. That's why I'm specifically saying "assumptions about UEOS/UEIS".)

Quantum mechanics limit the spread of information to the speed of light, most wave functions including the fundamental forces propagate at the speed of light and acceleration requires increasing amounts of energy the close your come to the speed of light.

I guess one way to look at where this comes from is to look at Conway's Game of Life. A cell in this game spawns if enough neighbors are present and with some trickery you can make things that move. But due to the rules of the game, nothing moves faster than 1 square per round.

There is no explicit rule that the speed of light in that game is 1 square per round, it's just that the way the rules work, the fastest thing could only possibly be that fast. Everything is limited to this speed that doesn't exist in the game.

If you changed the rules to allow cells to die or spawn depending on cells up to 1 square inbetween in distance, the speed of light would be 2 squares and none of the rules will explicitly state this limit.