infinite space

Infinite space? Why not?

How are you so sure this infinite space exists in the first place? It could just as well be finite.

An infinite universe would have infinite mass, but that mass would be distributed throughout an infinite volume of space. So the average density (plus initial conditions) will determine if the universe will collapse.Now, what are some of the other so called contradictions associated with infinite space?

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Ok, so you get infinity over infinity. That's one, isn't it?

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No, there is nothing logically inconsistent about that. An infinite volume of space (cosmological principle assumed to be correct)has an infinite amount of galaxies, which in turn have an infinite amount of stars, etc. That's what you get from infinity. Counter intuitive, but consistent.

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Well, why would the universe be infinite in every direction in space, but only infinite in one direction of time (the future)? That seems weird to me.

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Well it would seem odd to have a bunch of infinites in continuous space and 3 other dimensions but not time. But that is still just an arbitrary choice, ie. imposing human preferences on the universe. There's also no guarantee that time did in fact have a beginning. That is because we already know the standard model is wrong.

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Just to be sure, we're clear on the fact that there's no way to tell who's right here, right?

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Yes. Both an infinite universe and a finite one are logically consistent. Cosmological models based on GR also allow for both possibilities, given enough intital assumptions.

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There's no conclusive evidence for either an infinite or finite universe. So, does it really matter? Honestly the reason I believe in a finite universe is that it just seems, I dunno, simpler.

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Believe it or not, an infinite universe is the simplest solution for a flat universe. In order for it to be finite, it must have a multiply connected topology, ie. a shape with a hole(s) in it. And since infinities show up in so many other places, an infinite volume of space doesn't seem so odd. I think time is the lone hold out right now.

Cyclic models are hard to rule out, however. Without a good way to know anything about quantum gravity, there is a lot of speculation around the really doesn't amount to much. For example, the cosmological constant that is now causing the universe to accelerate could reverse to have positive pressure and cause space to contract.As I said, it's all speculation but we'll need to know something about quantum gravity to describe the earliest moments of the universe in the first place.

What does infinite space explain that finite space cannot? Either finite or infinite space brings up the issue of a beginning.

I meant a beginning of time. An infinite universe still gets stuck with that problem. As well, a finite universe also has no edges or ends.

And a universe of infinite volume also has a beginning. We're back to where we started.[This message has been edited by Beercules, 11-10-2003]

This is not a claim based on any science. The "void" described has never been observed, is not required by any current cosmological models and there is reason to believe such a thing even exists at all. You might as well argue the universe is expanding into heaven where Jesus and friends dwell.[This message has been edited by Beercules, 03-24-2004]

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Yep, this is true, but the plain fact that the models work, the absolute vacuum model explains too much to not be right.

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You'll have to clarify. What pheomena can the "absolute vacuum" explain even in the slightest? If the "void" is not part of the observable universe, then I don't see how it can offer an explanation to any physical processes that take place within it.

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There is a problem tho, you can never see it, because until the edge expands to occupy more of the void, and as things become observable the void remains beyond our physical perception.

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Modern cosmology suggests a finite universe has no edge. A universe where space is curved to the extent that there are no boundaries (and no center) simply cannot be embedded in a flat 3D vacuum. The only way to save the concept is to propose that our universe is embeded in a 4 dimensional (spatial) void. That ad hocery, along with a lack of explanatory power makes me wonder why anyone would find such an unscientific idea appealing. My guess is, it's just a matter of intuition and not any actual rational thought.

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It is expanding without decay, nothing else we have experience of does this, the 'bang' has need of some 'power' to keep doing what it is doing

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The energy provided at the big bang is enough for the expansion of space to continue forever, gravity pending. In the same way that an object hurling through space will never stop unless acted on by a force, space does not need to be constantly pushed.

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the power is the endless void, but only because it is the perfect nothing, there is no way to measure the extent of nothing, it is the one true infinity.

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What is this supposed to mean? Why would a "void" provide power? Have you put any thought into this??

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The void has no dimensions

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Ok, so the void has zero volume which means it has no size. IOW, there cannot be an infinite void, because you've just said it has zero volume.

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No dimensions can be imposed on it as it simply does not exist only as we expand into and occupy it does it take shape and form.

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IOW, the void does not exist at all.

Sadly, I've come across many individuals who post very similar unintelligent drivel who are in fact, dead serious. I'm afraid it is no longer possible to tell the trolls from the hurting individuals.

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I simply don't believe that's the view of science. Spacetime is a very real participant in interactions in the universe. It's not just an empty stage for matter and energy.

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The problem that I find to come up with the discussion of whether or not spacetime actually is a "thing" is that it ultimately comes down to semantics. Einstein's general relatvity reveals that spacetime and the gravitational field are equivalent. One could take this finding and conclude that spacetime has no existence independent of the gravitational field. And the source of gravity is energy. No energy means no sources, no gravitational field and no spacetime. On the other hand, one could just as well claim that there is ultimately no gravitational field - only curved spacetime. Semantics, and more of an ontological matter than scientific.However, science does agree that spacetime is not an empty arena in which events take place. Matter effects the curvature of spacetime and the geometry of spacetime effects the behavior of matter. That is why the absolute vacuum proposed by V-bird is a completely useless and irrelevant concept for physics.[This message has been edited by Beercules, 03-25-2004]