Sentynel wrote:Also, as it happens the universe isn't infinite.

Bwah? Really?

Yeah,
I watched a thing of parallel universes, then read for an hour on the net.
And nope.
Well.
Probably not.
Can't be proven.
Yet, or ever, pick a side.

But but but... what happened to Einstein? =P

Einstein said "there are only two things which are infinite, the universe and human stupidity, and I'm not sure about the former." To clarify, it is possible that the universe is infinite, but by no means certain. It's not bounded, but that doesn't imply infinite volume. (It could also be infinite in some directions but not others.) Whether the universe is infinite or not depends on its average curvature (this also determines the final fate of the universe) and the precise topology. (No, it doesn't make much intuitive sense that the universe could have started 13.7 billion years ago and be infinite in extent, but it is possible..)
On a slight tangent, it's easy to show that the universe cannot be infinite in both time and space, because if it was, the night sky would be as bright as the surface of the sun. Of course, as we know the universe is not infinite in time, it could be or could not be infinite in space. Or both, as I mentioned earlier.

Thanks. Is it at all possible to eventually know for sure?

Well, if we're still around in a few billion years we'll know for sure. It's entirely possible we could work it out long before that, of course.

Yep.
Course, that assumes the Universe is in fact curved (and so just subtly enough so as to be unmeasurable), and not flat.
The eight year old in me likes the idea of a flat universe, just cuz.
I personally think it's just curved enough that we can't see.

It doesn't matter what curvature the universe has; if we wait long enough we'll know about it. If the universe does indeed have 0 curvature (i.e. is flat), it'll be just as clear as if it's got positive or negative curvature in a few billion years' time.

Sentynel wrote:Well, if we're still around in a few billion years we'll know for sure. It's entirely possible we could work it out long before that, of course.

If everybody stopped being "normal", became "weridos" and started thinking for themselves, that time frame could be decreased by a few million years.

In a few billion years it'll be obvious. Depending on how close our theories are and how lucky we get advancing them, we could conceivably know to a reasonable degree of certainty within our lifetimes.

With luck, we will.

I dunno about that. It's going to be pretty tough to prove the universe isn't never-ending. And with the technologies we have, I would say-no hope! Heck, we don't know for sure if water is present in Mars & we havn't found a cure for AIDS in decades! I agree with Sent's previous statements-it might take a few billion years. And with luck, thousands, if not millions. We just don't have the technology to study universe in that much detail.

nathanielandbartimaeus wrote:Heck, we don't know for sure if water is present in Mars

Objection: we do now. It is.

Yeah, haven't we known Mars has ice caps for ages now?

We have indeed. The Phoenix lander confirmed a few months ago that water ice is present below the surface well beyond the ice caps.

A collection of Calvin and Hobbes

And Terraforming is awesome

Sentynel wrote:We have indeed. The Phoenix lander confirmed a few months ago that water ice is present below the surface well beyond the ice caps.

Ouch. I remember now reading in the newspapers about that. But somehow it never registered. Water hasn't been found in the moon, right?

It's known there is water on the Moon, but not whether there are useful quantities of it.

Yep.
Useful quantities could be very useful indeed: seperate H and O and there ya go, rocket fuel.