It's expanding in all directions - does that mean it's a sphere?

That is the conventional wisdom, yes.

Hi! JoeNormal, welcome to AMHD :)

Quote:

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Originally Posted by JoeNormal

It's expanding in all directions - does that mean it's a sphere?

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Not necessarily, it could be a lumpy sphere. There are struggles between the momentum of expansion and the pull of gravity that may determine its shape.

Such as:
A Hyperdodecahedron
http://lh5.ggpht.com/_80cGISOzOds/Sv...decahedron.jpg

Or a Hyper-toroid
http://lh5.ggpht.com/_80cGISOzOds/Sv...Hyperspace.jpg

Or Open or Flat
http://lh4.ggpht.com/_80cGISOzOds/Sv...esuniverse.jpg

Closed has been ruled out because the math proves that if it was closed, the Universe would have collapsed in on itself.
Curious About Astronomy: What is the shape of the universe?

No one is still sure.

If you can spare 29:12 relax, and enjoy this:
Podcast: What is the Shape of the Universe? | Universe Today ,
You can download and play on Win Media Player or save.

More visuals:
An Atlas of The Universe

More interestng conjecture:
We are in a Schwarzschild black hole--T or F?

I suppose the actual question is where to you define the edge of the universe?

The furthest galaxy out on a particular access?

A point equidistant from the center of the universe?

Map to each outside point where there is no galaxy or object further and connect the points with planes?

Personally, I would measure from the center of the universe to the furthest real object and form a sphere with a radius of that distance.

Or like KUXJ says... no one really knows. Yet.

Stevecg - you're thinking in 3 dimensions, and so are assuming that the galaxy is a shape that has an edge to it. But there is no such thing as "the furthest point out," nor "the center of the universe." Every place in the universe is at the center of the universe! No matter whch way you look in the sky you see approximately equal numbers of galaxies in all directions and at all distances, receding away from us at a rate that is dependent only on how far away they are (per Hubble's law), not which direction they are. Does that mean that the earth is at the center of the universe? In a sense it does. But it turns out that if you could travel to a galaxy that is 12 billion lihgt years away (about as far away from eart as anything could be), and looked around you would find that again you see equal number sof galaxies in all directions in the sky and all receding according to Hubble's Law. Conclusion: every place is at the "center" of the universe, and no place is at the "edge."

Well, that is subscribing to the theory that there is only one universe. I don't believe that.

Although, if you ask my kids, they are the center of the universe.

And your theory is a bit off. You are talking about perception, not actual distance. If you sit on a boat in the middle of the ocean and look in any direction it looks the same... but you aren't necessarily in the center.

I don't believe that the universe is infinite so therefor HAS to have a center.

Quote:

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Originally Posted by stevetcg

Well, that is subscribing to the theory that there is only one universe. I dont believe that.

Although, if you ask my kids, they are the center of the universe.

And your theory is a bit off. You are talking about perception, not actual distance. If you sit on a boat in the middle of the ocean and look in any direction it looks the same... but you arent necessarily in the center.

I dont believe that the universe is infinite so therefor HAS to have a center.

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It's hard to get your head around this, but I agree that the universe is not infinite in size, and yet it does not have a center, nor an edge. You are of the opinion that the universe is like a big football, and sits inside something that is even bigger (that's the only way it could have an edge). Which just begs the question, because now you have to ask yourself: what does that larger universe sit in, and does it have a center?

If its not infinite, it HAS to have a center. If it does not go on forever (real forever, not just what we can perceive) then it also has an edge.

The big bang theory has everything starting at a single point so therefor that 'should' be roughly the center.

I am of the opinion that the universe sits inside of something larger.

But stcg, there is no center to the Universe, and the Universe is more expansive than the farthest object.

See... but if the Big Bang was an explosion, at:
Where is the center of the universe?
It was an explosion of space, not an explosion in space. According to the standard models there was no space and time before the Big Bang. There was not even a "before" to speak of. So, the Big Bang was very different from any explosion we are accustomed to and it does not need to have a central point.

The Einstein field equations (EFE) leave each point in the universe equivalent to any other point; there's no center and as far as we can tell, this is how the universe behaves, the shape of the universe is the same wherever you stand.
With the non-linearity of the EFE, finding exact solutions is difficult, if not impossible because of human kind's inability to comprehend the subject matter.

For now I believe in a muti-verse, but not one designed like Russian Eggs.
It sure makes my head hurt when I think' about it too long...

The universe, said J. B. S. Haldane, is not only queerer than we suppose, but queerer than we can suppose.


Anybody see JoeNormal?

So the answer to this question:

The shape of the universe is Maybe.

This whole conversation reminds me of a book I read 20+ years ago. I think it was called Flatworld. It was a 2 dimensional world populated by geometric shapes. Everything went well until a sphere showed up. People simply could not comprehend 3 dimensions.

Like me and astrophysics.

Anybody see JoeNormal?[/QUOTE]

Hi KUXJ - I am here. Thanks for your thought-provoking reply - and to everyone else too. I'm new here and didn't realise I'd get such a wealth of material in such a short time! Let me check out that podcast before I give a proper response.