Does Space really go on forever?

[Birchy]

hi there, its my first new thread and my first post on the astonomy forum. Normally I'm browsing the bird forum.

Am interested in space, planets, ufo's etc. But don't really have a brillant knowledge of this subject. I just wondered, even though nobody actually knows, if space just goes on forever?
I know that space is MASSIVE!!!!!! But how can something go on and on and on without there been an end. When I think about it, I just end up getting head ache becuase I don't get it.

If there's any experts out there, if you don't know the answer, could you make suggestions at to how space might possibly end.

I probably reckon that this subject has been discussed before but I haven't been a member of the forum for that long.

[jnb]

The usual analogy is with the surface of the Earth. The surface of the earth goes on forever but it is finite.

The surface of the Earth is two dimensional but unbounded because it curves around a three dimensional sphere so one could travel in any direction across the surface of the earth forever without encountering an edge.

Similarly space is three dimensional but unbounded because it curves around a four dimensional "hypersphere" so one could travel in any direction through space forever without encountering an edge. (actually that's a simplification space is assumed to curve in all sorts of bizarre ways according to what's in it as stuff like black holes and so on deform space and it probably curves in about 11 dimensions but the analogy is good)

[Interpreter]

It will all be explained on the TV next week.

BBC2 7:30 Tuesday. The Cosmos: A beginners Guide. Family Choice in the Mail TV Magazine.

[Birchy]

Thanks alot guys.

That's very interesting jnb. I think I could get into this astonomy forum. I did know a little about the universe being sort of sphere like and also that it's forever expanding. I've seen a few programs on sky.

I will make sure I see THE COSMOS on tuesday, cheer's interpeter.

[Adam Cheeseman]

Similarly, if the universe is constantly expanding, what is it expanding into?

Cheers,

Adam

[SparklySarah]

Originally Posted by Adam Cheeseman

Similarly, if the universe is constantly expanding, what is it expanding into?

Cheers,

Adam

Now there's an interesting question! Doesn't seem posible for there to be anything for it to expand into, if it can go on forever! Maybe next weeks programme will shed a little light on this. Won't see it though, off on hols. Do tell what it says!

Sarah

[eeyore]

Originally Posted by Adam Cheeseman

Similarly, if the universe is constantly expanding, what is it expanding into?

Cheers,

Adam

i think the definitive answer is that its impossible to say because the edge of the universe is going away from us at the speed of light. some scientists speculate that eventually it will start to contract and evwentually we will all get squished like a particularly unfortunate hedgehog

also as i understand it beyond the edges of the universe nothing exists in a form we can understand because the laws of space and time do not aplly in undimensional N space - well you did ask

[Jez]

if space is constantly expanding then what is beyond space then? Just more space

[jnb]

"What's beyond space?" is a meaningless question in the same way that "what's north of the north pole?" is a meaningless question.

Broadly speaking the big bang is the point at which everything is created including all energy, all matter and all of space and time. As of the big bang space itself has been expanding and carrying all the matter and energy within it. It's not that its an area of space into which things expand instead it is all of space within which there are things.

If you want an analogy imagine a balloon on which are drawn tiny points representing all the galaxies. As the balloon expands all the galaxies rush away from one another but no one point on the balloon's surface is the centre from which they all rush away and there is no meaningful concept of what the balloon is expanding into (ignoring the fact that in the analogy the balloon expands into a third dimension but all analogies break down if pushed too far). There is no "beyond" space just as there is no "before" the big bang and there is no north of the north pole.

It might not be intuitive but it appears to be the way it works.

[Jez]

Just checking