[1veedo]

OP:

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i was recently reading a book called 'The Universe In A Nutshell' by: Steven Hawking. He said that the universe DOES end somewhere. He knows this because if the universe was infinit then that means everywhere we look there would be a star, and the night sky would be as bright as the sun.


so in other words if the universe went on forever then there would be a star EVERYWHERE we look. But there isnt. So the universe must end at some point

I don't know if anybody has answered this, but I remember reading exactally that in the book abut a year ago. He was talking about a static universe; one that is not inflating. In a static universe, the light from stars would be so intence that night would be as bright as day. This has nothing to do w/ weather or not space is infinite.

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If the universe was static and infinite in every direction, every line of sight would end in a star; which would make the night sky as bright as the sun.
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Sky is dark...Implies that the universe cannot have existed forever in the state we see today.

All this means is that the unvierse had a begining; if it were static, the night sky would be bright.

[Zeo]

Cadmus said:

The point is the linear dimension did not exist before the big bang, and did exist after the big bang. Therefore, it is possbile to consider that it, and other dimensions, came into existence with the big bang. This statement is contrary to your statement. My point is that I think that your statement in the earlier post is not necessary.

My argument on this saying that an explosion can create a dimension and whether or not the big bang can be used as a suitable reference to support that argument is this: No. What you're saying is indeed conceivable, but that's to say that the universe didn't exist at all, and that there was absolutely nothing before hand.

Which leads me into my next argument: The big crunch. Supposedly, when the universe reaches it's ultimate mass (size, volume, whatever), the sheer gravity of all of it's bodies will begin to draw in the universe and everything it is . . . including (I think), the edges. I might be wrong, but it's been hypothesized that our universe originated from a ball of energy that arose from a big crunch.

Maybe I'm wrong.

But Maybe I'm right.



In reference to the topic, my teacher was telling me about a space anomaly that was traveling through space that was recorded by Hubble. Hubble saw that the anomaly approaced the proposed "edge" of space, left space (the universe that is), and then came back, somewhere else. Which leads me to think: What if beyond the edge of this universe is another? But then, if our universe is spherical, what universe lays outside? What shape would that have?

Does the universe have a shape?
My head hurts.

[Comandante]

soulestada said:

I think that maybe if the universe is infinite, then maybe there are stars that are hundreds of billions or trillions of ly away, and that maybe their light has not reached us yet.

I say that if there were stars that far away there would probably be other stars in between, for example you wouldn't have an empty space of trillions of ly apart, there would PROBABLY be some stars in between; and IF there were then the number of stars we see over years would increase because the light emitted would start to reach us... Does this happen? Anyone kept track of exact number of visible stars ;) ?

[ed84c]

No, the stars and galixies are "patchy" so hence there are regions of empty spave and regions of not-so empty space.

The good example of that is that, galixies are arranged in "Branches" with nothingness in between (well the odd one or two stars in a bn square light years).

There is half a dozen hydrogen atoms in the size of a matchbox of this empty space, so its pretty damn empty.

[Newtonian]

One cannot fully comprehend how vast the universe is,there's alot of empty space.Distances of systems are so far away from each other they become irrelevant.Which has its benefits especially to our little planet.No other star system is near enough to supernova and render our planet a charcoal quarry for alien pencil manufacturers.

[Comandante]

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No, the stars and galixies are "patchy" so hence there are regions of empty spave and regions of not-so empty space.

The good example of that is that, galixies are arranged in "Branches" with nothingness in between (well the odd one or two stars in a bn square light years).

There is half a dozen hydrogen atoms in the size of a matchbox of this empty space, so its pretty damn empty.

interesting, so you think it is a high possibility that there is a bunch of stars, i.e. another globular star cluster too far away for its light to have reached us? I know you didnt' comment on that but I'm curious... I personally think there isn't...

[bascule]

I think certain individuals on this thread are really thinking about the problem incorrectly.

Our best information to date paints a picture of an extremely flat universe. That doesn't necessarily imply an infinite flat universe, but if the universe is closed (either in a positive sphere or a negative saddle) then it is very, very, very big, to the point that it appears to be flat. Figuring out why the universe seems so flat is a rather vexing problem in science today.

Note that if the universe truly is closed, it's impossible for an "edge" to exist as the curvature of spacetime would merely wrap back on itself. This is the anticipated behavior of the 6 "compactified" dimensions in string theory, they are simply curved so tightly in comparison with the three spatial dimensions of ordinary experience that they don't even seem to exist in our ordinary, everyday lives.

[reverse]

This is reminding me of the ancient sailors setting out over the Pacific ocean. Quite Sure that they were heading for the edge of the world.

They saw that the Earth was flat, their eyes told them that,
but can you imagine their surprise when they got to the edge of the world and it was the beginning again.

How would they understand (from what they knew) that sitting at home in their kitchen, they were already standing on the edge of the world - and the real exit door was straight up.

[island]

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I think certain individuals on this thread are really thinking about the problem incorrectly.

Our best information to date paints a picture of an extremely flat universe. That doesn't necessarily imply an infinite flat universe, but if the universe is closed (either in a positive sphere or a negative saddle) then it is very, very, very big, to the point that it appears to be flat. Figuring out why the universe seems so flat is a rather vexing problem in science today.

Maybe not so tough after all, if we don't run-off on every cutting-edge theoretical tangent that happens to be the flavor of pop physics writers following... "seekers of supersymmetry":

1) Without a perfect cosmic singularity, characteristics and traits of our universe, (like, flatness and the rest of the force parameters), can be inherent and cast-forth into our universe from a previous one, by a big bang... e.g. the metric that's set-up by the matter distribution during the initial conditions was pre-determined by that which existed in a previous universe.

2) Vacuum expansion is caused and counterbalanced by particle pair creation. e.g., the increase in negative pressure, (antigravity), that's inherent to an expanding universe, gets offset by proportional increases in gravity. This will hold the universe nearly flat as this finite closed near-flat spherical universe expands in accordance with General Relativity, with a cosmological constant.

3) Which also resolves the horizon problem without the inflationary "band-aid" scenario, because the offset increase between gravity and vacuum pressure means that tension between the vacuum and ordinary matter increases instead, so the forces will eventually be compromised and the universe will have volume when a big bang occurs... just like the last one... and the one before that...

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Note that if the universe truly is closed, it's impossible for an "edge" to exist as the curvature of spacetime would merely wrap back on itself. This is the anticipated behavior of the 6 "compactified" dimensions in string theory, they are simply curved so tightly in comparison with the three spatial dimensions of ordinary experience that they don't even seem to exist in our ordinary, everyday lives.