Where does the universe end?

lemonkettaz said:
What? so after 90million light years, things move faster than the speed of light?
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Sorry you are confused.

Outside the horizon, space is expanding faster than light speed. The distance to that horizon is 90billion light years (larger than age of universe btw)

sid
 
Doosht said:
Surely matter can not just be infinite and go on and on and on...........................................................................................................................and on and on !


(sits back with big bag of crisps and waits for OCUK'ers minds to implode) :D
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And if there's:
a) no time beyond the edge can you travel beyond it?
b) infinite time - is the universe static in size?
 
Stovies said:
what is space expanding into?
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Also if 0.999999... = 1 can a universe expanding be considered to be at it's full extent of expansion?

Actually we may have a static size of universe however everything in it could be shrinking instead. The illusion of expansion.
 
It doesn't, we simply don't have the capacity to understand infinity.

Also for all the "space expanding" questions, basicaly space is expanding INTO itself, not the universe, heres a good analogy:

I stretch a tape measure to the moon from earth, for the purpose of this explanation, it reads 100m.

I leave it for 100 years.

I then go back to the tape measre, it still reads 100m but when I real it in, the tape measure has stretched to 200m long.

Basicaly space itself is expanding, all of it, all the time, so rather than the universe expanding like a balloon, air is being put into the balloon, without it expanding.

I know my head hurts to.
 
sid said:
Sorry you are confused.

Outside the horizon, space is expanding faster than light speed. The distance to that horizon is 90billion light years (larger than age of universe btw)

sid
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If the space outside the horizon is expanding faster than light speed how dose space inside the horizon keep up? given that the horizon is the edge of known space already created. In theory you would the have a gap appear behind the advancing space as it left the horizon of known space behind, being that the horizon of known space was slower the the advancing space. If that created a new horizon of known space as the first sped away then the 2nd expansion would pull away from the 2nd horizon, and so on, repeat forever....................., so we are in a pool where a pebble was thrown and the ripples at the edge speed away from the ripples behind and a ripple behind can never catch a ripple in front....................I give up :confused:
 
I don't understand why people can't grasp nothingness/vacuums.

Surely it should be harder to comprehend that between your face and your monitor there are a billion particles of oxygen that are completely invisible. Nothing is easy in comparison.
 
rghjones said:
I don't understand why people can't grasp nothingness/vacuums.

Surely it should be harder to comprehend that between your face and your monitor there are a billion particles of oxygen that are completely invisible. Nothing is easy in comparison.
Click to expand...

I know where its going but its hard to see how its getting there with 1 horizon travelling slower than the space in front of it. If that was true the space would leave behind the horizon and create a new horizon, and so on, again and again until the universe stopped expanding and the horizon was no-longer left behind because space had stopped travelling faster than the horizon.

Yeh......................, ill have some headache tablets now............ :confused:
 
Whether the universe is finite (bound) in size depends on it's geometry, which is intrinsically linked to the density of the universe. If the universe is destined for a 'big crunch' then it has a bound geometry, this essentially means the 3d spatial universe we see is wrapped around a 4d sphere, if you go far enough you end up where you started. This is possible to imagine if you go down a dimension, ie imagine the 2d surface of a 3d sphere, it is finite and if you go in a straight line on the surface you can end up where you started. If the universe is destined to expand at a more or less constant rate then it has a flat (euclidean) geometry that goes on for ever, you can think of this as an infinitely large cubic grid (the energy contained within can still be finite). If the rate of expansion of the universe is increasing then it has a hyperbolic infinite geometry, this is the hardest to visualize. 3d space is being stretched through the 4th dimension, i've not really heard of a good way to visualize this.

Their is some interesting reading here, but it is quite mathematical;)

Essentially in answer to the thread title the universe doesn't have an end, it either carries on forever or folds back on itself.
 
When they talk about space expanding do they mean space like a kind of fabric that is expanding itself or space as an empty area dimension where the things in it are moving away from each other?

If space goes on forever in every direction wouldn't it be quite likely that the chances are other big bangs have happened out there far past the horizon we can see in our visible universe?

I don't think i've quite heard the multiverse theory put this way before, i've always taken it to mean universes existing in separate dimensions and not in our own space time, personally i don't believe multiverses existing in separate dimensions but i do think a small amount of dimensions exist in a sense as we have three dimensions of space, it's possible there's three dimensions of time, well time like at least.
 
Space expanding is the 'fabric' expanding, the distances between galaxies measurably increases. A good analogy is to think of baking bread with raisins in it, as the dough expands the raisins get further apart proportionally to their original distances.
 
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