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

[Interpreter]

Personally, I believe in a modified version of the 'Big Bang' theory. I believe that there have been many 'Smaller Big Bangs' which is why everything is not expanding in the same direction.

There is no difference between energy and matter: it is just a different form of the same thing. You cannot destroy matter, only change it's form. Therefor matter/energy is forever.
Space expands and then contracts until it is converted back into pure energy at the maximum concentration possible. Then the capture of a single electron would push it over the edge and start the 'Big Bang' again. I have no idea how long this process takes, but I have been here since 1940 and it hasn't happened yet!

Another interesting point is that the average time taken for huge hits on the earth is one every 100 million years. Now it takes our solar system 200 million years to rotate. It looks like this would put us in the path of a stream of material once every 100 million years. Hmmm.....

Dodgy subject, but how can this be explaned without a creator? Nothing is ever formed spontaniously from nothing. Where did the original energy come from?

[jnb]

Originally Posted by Interpreter

Personally, I believe in a modified version of the 'Big Bang' theory. I believe that there have been many 'Smaller Big Bangs' which is why everything is not expanding in the same direction.

A reasonable picture if you look at space in terms of classical mechanics. One could have multiple explosions within space but that doesn't answer the question of where the space and time within which those explosions occur originated.

Originally Posted by Interpreter

There is no difference between energy and matter: it is just a different form of the same thing. You cannot destroy matter, only change it's form. Therefor matter/energy is forever.

Broadly true but there was a general separation of the two after the big bang. Energy and matter "decoupled" about 300000 years after the big bang up until that point the energy density was so high that there literally was no difference between the two. It isn't quite true that it is forever as there are various tricks at the quantum level and phenomena such as radiation from black holes (again not intuitive but can happen) which allow those rules to be broken to some extent.(NB those numbers could be wrong - it's been a few years since I read astrophysics)[/quote]

Originally Posted by Interpreter

Space expands and then contracts until it is converted back into pure energy at the maximum concentration possible. Then the capture of a single electron would push it over the edge and start the 'Big Bang' again.

Ah but if 'space' has contracted then from where does it capture that single electron. There is no outside from which to capture it.

Originally Posted by Interpreter

Dodgy subject, but how can this be explaned without a creator? Nothing is ever formed spontaniously from nothing. Where did the original energy come from?

Which of course just begs the question of where did the "creator" come from?

(NB I think we may have deviated somewhat from the forum topic of 'wild about Britain' )

[Interpreter]

Originally Posted by Interpreter

Then the capture of a single electron would push it over the edge and start the 'Big Bang' again.

This assumes that the total mass of all of the energy would not be stable. In it's maximum stable form the 'lump' of energy would consist of all of the energy less that single electron. Unless of course there are multiple examples of the 'Big Bang' in existance in different parts of space at the same time.

The simplified example that was often quoted when I was studying physics was that if you imagine a proton the size of a football sitting on your diningroom table, then there would be an electron the size of a small orange a hundred yards or so away, in orbit around it. In between the proton and the electron would be nothing. So solid material consists mainly of nothing.

[eeyore]

Originally Posted by Interpreter

So solid material consists mainly of nothing.

hemce the theoretical possibility for you to walk through a brick wall if your matrix of nothings was lines up exactly with the matrix of the walls matter. This must be an infintesibly small chance tho because I have tried it many times at closing time and never succeded yet

It is also apparently possible for a single electromn to be in two places at the same time - nowe that would be a useful ability to master , especially looking at the size of my in tray pile (of course another option would be to spend less time on wab .... but i mean come on thats just a ridiculous idea )

[Jolanta Zofia Nowak]

Most of the detailed science is beyond me but aren't we still in the debate of whether the universe is gravitationally 'open or closed'?

'Dark matter' is the dark horse in all of this, no?

[Jez]

eeyore you need need top quality trainers and run faster

[thunder]

Originally Posted by eeyore

hence the theoretical possibility for you to walk through a brick wall if your matrix of nothings was lined up exactly with the matrix of the walls matter. This must be an infinitely small chance tho because I have tried it many times at closing time and never succeded yet

But eeyore, have you never woken up and said to yourself "How did I get here?"? If you have, it's likely you just walked through a series of walls.

henrya

[jnb]

Originally Posted by Interpreter

This assumes that the total mass of all of the energy would not be stable. In it's maximum stable form the 'lump' of energy would consist of all of the energy less that single electron. Unless of course there are multiple examples of the 'Big Bang' in existance in different parts of space at the same time.

The simplified example that was often quoted when I was studying physics was that if you imagine a proton the size of a football sitting on your diningroom table, then there would be an electron the size of a small orange a hundred yards or so away, in orbit around it. In between the proton and the electron would be nothing. So solid material consists mainly of nothing.

Which is a simplified example as if it was really in orbit then you would have a charge spinning in a em field which means that it would have to radiate energy. If it radiates energy the atom would collapse as it loses energy. Of course if it was static then it would collapse as the EM field would drag the electron into the nucleus. It's perhaps more accurate to regard the electron as merely having a probability of being somewhere around the nucleus. So in the classical model the atom is a largely empty space with a few orbiting electrons while in a quantum model and atom is a grey fuzzy cloud of probabilty.

Of course at the astronomical scale space is largely empty anyway.

[Jolanta Zofia Nowak]

I liken space to my hubby's mind - dark, full of weird things and apparently inaccessible for the most part...

[Dogghound]

Where in a massive marble and two giants are having a game of playing marbles with us, i challenge anyone to prove me wrong ,

Seriously though i think its a question that is impossible to answer.

[Jez]

i think
mines very similiar

[newfie2007]

i got a lot of stuff of the earth and spaces i well look for it and post it on here some time tomorrow ok .

[Ambriel]

Originally Posted by Adam Cheeseman

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

Blancmange?

[C C]

I am probably like most, the more i try to grasp the idea of space, the more it blows my mind. Has anyone checked out the hubble ultra deep field, the one you can zoom in.
hubblesite.org/newscenter/archive/releases/2004/07

[Jolanta Zofia Nowak]

The answer to this one, actually, is quite simple and was worked out some fair time ago:

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