The Universe

[DooMBoy]

So, what do you think? Is the Universe infinite, or is there an end somewhere?

[fraggle]

There is a fourth option: the closed Universe. In this space is finite but bent round itself, so there is no edge or "center". It is like the surface (not the inside of) an expanding balloon.

[stphrz]

The universe is open. It does have a finite size, but that size is increasing constantly. Galaxies are flying away from each other and the closer they are to the edge of the universe the faster they are moving.

So there is an edge to the universe, but that edge is expanding.

[CyRaptor]

Infinite in the sense the if you start at point A and travel in a straight line you will end up back at point A eventually. It's sort of like a loop. Or something.

[Opulent]

stphrz is right, IMO.
although, I disagree with the notion that the universe will cascade and shrink after expanding.
I think it will always expand.
there is no gravimetric reason it would collapse to an anti-bigbang.
if you could somehow teleport to near the edge of the cosmos, I'm sure there is an impassible "wall" that is the outer edge of the universe. Just like the environment of a blackhole, you can't even force light to the actual edge. There is no evidence of the universe being bent around itself.
lastly, I don't think humans will ever be able to transport physical objects beyond, say..., 2/3rds the speed of light. so we may never know the answers to these questions.

[Epyo]

Ahhhh... I just dont want to think about it

[Coopersville]

It has an end to it that is slowly expanding. I don't wanna be around when it snaps back and shoots everybody's eyes out.

[DooMBoy]

As for me, I personally think that even if there were an end to the Universe, how would we possibly ever find it?
Will we ever now for sure?

[stphrz]

DooMBoy said:

As for me, I personally think that even if there were an end to the Universe, how would we possibly ever find it?
Will we ever now for sure?

Well it all depends really what you define the universe to be. If you are talking in terms of the "volume" or extent of the the three dimensions we are familiar with then you could say it is infinite (no boundary). If you are talking about the space occupied by all the matter in the universe then it's size is finite (probably). I don't think we can ever be sure.

[Y2theJ]

This topic is far too advanced for me. And my head hurts. :P
Umm... I am my universe and have absolute control over it/me. ;)

[AndrewB]

Moron. The universe is ever-expanding. It's only as big as matter and light have spread. It's not enclosed but it's not infinite either.

[Disorder]

stphrz said:

The universe is open. It does have a finite size, but that size is increasing constantly. Galaxies are flying away from each other and the closer they are to the edge of the universe the faster they are moving.

So there is an edge to the universe, but that edge is expanding.

AMEN. Scientists already know this..

[Fredrik]

Stphrz - you're wrong. It's like fraggle and AndrewB said. The universe is finite in size but it doesn't have any edges or center.

Perhaps you've considered the fact that a 2D surface can be finite but still not have any edges? Look at the Earth or any sphere for proof. The 2D surface is wrapped around a 3D object. The same actually applies to 3D space. You could picture the universe as a 3D surface around a 4D sphere (or balloon). The space is finite but it doesn't have any edges, and it doesn't have a center either. The expansion of the universe is identical to the expansion of the said balloon.

If you are talking in terms of the "volume" or extent of the the three dimensions we are familiar with then you could say it is infinite (no boundary). If you are talking about the space occupied by all the matter in the universe then it's size is finite (probably).

Wrong again. There is nothing such as empty dimensional space outside the boundaries of the universe. All dimensional space - virtual as well if you like - is restricted to the scope of the universe itself.

And there's no indication whatsoever that the universe will ever collapse due to gravity - in fact, it appears that the rate at which the universe is expanding is accelerating.

[GS-1719]

The universe is finite in size, but the speed at which it is increasing in size is decreasing.

Now how would you define an edge? In Euclidean or relativistic geometry? Edges do not have to be visible.

[stphrz]

Fredrik said:

Stphrz - you're wrong. It's like fraggle and AndrewB said. The universe is finite in size but it doesn't have any edges or center.

Perhaps you've considered the fact that a 2D surface can be finite but still not have any edges? Look at the Earth or any sphere for proof. The 2D surface is wrapped around a 3D object. The same actually applies to 3D space. You could picture the universe as a 3D surface around a 4D sphere (or balloon). The space is finite but it doesn't have any edges, and it doesn't have a center either. The expansion of the universe is identical to the expansion of the said balloon.

Wrong again. There is nothing such as empty dimensional space outside the boundaries of the universe. All dimensional space - virtual as well if you like - is restricted to the scope of the universe itself.

And there's no indication whatsoever that the universe will ever collapse due to gravity - in fact, it appears that the rate at which the universe is expanding is accelerating.

Like I said before: "If you are talking in terms of the "volume" or extent of the the three dimensions we are familiar with then you could say it is infinite (no boundary). If you are talking about the space occupied by all the matter in the universe then it's size is finite (probably)." I never once said there was a universal center.

I also never said anthing about the universe collapsing in on itself, in fact I said the opposite.

Let me claify: The universe has a finite "age." Therefore we can only see so far (somewhere about 14 billion light years). However the three dimensions we exist in don't stop there. The balloon analogy you and Fraggle mentioned is a possible explanation as to how this can be. However, visualizing that is impossible. Three dimensional space does not "wrap around" like two dimensions around a sphere. If you fly off in a spaceship in a straight course at a speed far faster than the universe is expanding you will not eventually "wrap around" and end up at the same place again.

[dsm]

dsm: *yawn* Hmm, I wonder if the Religion and Politics has anything interesting in it today *browses through the forum mumbling to himself* hmm, more gun control shit, Christianity bashing, Scientific nerd talk, a shitload of articles proving US government conspiracy theories, *mumble mumble* wait! What's this? The Universe!? *browses through thread* Bah, same stuff as always, there doesn't seem to be anything really original here today, guess I'd better get my ass back to doing some writing..
*dsm logs off*

[Opulent]

No.
the "Ultimate Horizon", although physically viewed is wrong because of the gross timeshift for light to travel 14 billion light years, still obeys the laws of physics. the universe is a contorted ballon-spherical shape that is expanding. there is an outer 'edge' -- we are talking about physical space.
there is no empirical evidence that the universe wraps back upon itself.
if you could throw a rock at impossible speeds, it would stop moving at the ultimate horizon, about 15 billion light years from us.
to think differently is purely conjecture that there is a "fourth" dimension or that the laws of physics is different at the 'edge' or even outside the known universe.
We simply don't know enough about the creation of the universe to know what exists beyond what we can see. (meaning, perhaps the universe if even larger than we can see and older than 15 billion years)

[stphrz]

if you could throw a rock at impossible speeds, it would stop moving at the ultimate horizon, about 15 billion light years from us.

It would not stop moving. It would not "wrap around" and eventually end up at the point from which it was thrown. It would just keep going.

Actually you need at the very least five dimensions to explain the unverse, possibly more. There is no way as 3d creatures we could ever "visualise" such a thing.

[Fredrik]

Stphrz, you're more or less saying that the universe is an expanding three-dimensional sphere placed in a three-dimensional cartesian virtual space. This is a very intuitive way to picture the universe, but not necessarily true.

As far as we know, the universe could either be spherical, Euclidian-wrapped or superspherical. In the case of the last two, it'd have to wrap around itself. Most cosmologists and physicists today believe that the universe is of that nature. Why not? The concept of the universe having boundaries is absurd in my eyes.

I never once said there was a universal center.

I also never said anthing about the universe collapsing in on itself, in fact I said the opposite.

No, I should have made clear that that wasn't directed at you.

The universe is finite in size, but the speed at which it is increasing in size is decreasing.

The speed is increasing, this has been observed.

[DooMBoy]

Here's a good one: if through some miracle you could move at 40 times the speed of light and not even a black hole could suck you in, and you managed through another miracle to actually go past the boundary of the universe (assuming the universe has a boundary), what do you think you would see?

[Fredrik]

DooMBoy said:

Here's a good one: if through some miracle you could move at 40 times the speed of light and not even a black hole could suck you in, and you managed through another miracle to actually go past the boundary of the universe (assuming the universe has a boundary), what do you think you would see?

Seeing assumes there are photons around. And since there aren't any outside the universe, you wouldn't see anything at all.

[Y2theJ]

Seeing assumes there are photons around. And since there aren't any outside the universe, you wouldn't see anything at all.

Is this a theory. Or can you prove it?

[Fredrik]

Y2theJ said:

Is this a theory. Or can you prove it?

If there were photons, you wouldn't be outside the universe.

[Opulent]

Fredrik: Why do you think that the concept of the universe having boundaries is absurd?
that is the physical universe as we know and understand it.
You say that the universe is expanding(which I agree with), but how can it be in your eyes if there is no outer boundary? If the universe is not finite, then it is not expanding.
to think there is anything beyond the ultimate horizon is not science.

[Psyonisis]

The human mind simply cannot comprehend nothingness, which is why thinking about this stuff hurts my brain. Which is why it's strangely intriguing!

[Fletcher`]

It seems that everything that relates to the universe, and existance keeps reminding me of the Matrix. My head hurts.

[mmnpsrsoskl]

You there are probably more dimensions than humans have discovered yet and this is what keeps the fabric of space together.

Or I am just an idiot. Anyhow the fact that we are debating about something which will probably never be fully understood is absurd. Just accept the fact that the universe exists and we are living in it.

[Joe Doom]

Wow you people really know your stuff! I think that the universe is just like a baloon in that it has a finite size, but it is expanding.
By the way, do you think mankind will ever find intelligent life other than what is on the Earth? And I'm not talking about that crap in the tabloids either. I mean like for them to visit and settle on the Earth.

[Fredrik]

Why do you think that the concept of the universe having boundaries is absurd?

It's just not elegant. The theory assumes that there is some kind of virtual unused space outside the universe - with the closed-but-finite theory, you get a universe with no virtual unused space outside.

You say that the universe is expanding(which I agree with), but how can it be in your eyes if there is no outer boundary? If the universe is not finite, then it is not expanding. to think there is anything beyond the ultimate horizon is not science.

Just like with surface of the balloon, it's finite, it's expanding, there's no boundary. And no, there is nothing beyond the ultimate horizon.

[mmnpsrsoskl]

Heh, doesn't the Doom map have a finite size? like 32768 x 32768? or something? and when you exit one side you are at the other? heh, it's like the theorey mo bob Fredrik is talking about.