The edge of space

[EWright]

If you take three stars many light years apart and measured the angles between the stars the three angles would either be equal to a80 degrees, less than 180 degrees or greather than 180 degrees. If the angles add up to 180 degrees the universe is what is called Euclidian. If the angles add up to more than 180 degrees the shape is that of the outside of a balloon. If the angles add up to less than 180 degrees the shape is that of a negative balloon which I can not visualize.

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If we measure a positive curvature in space using the three stars, say roughly 3 billion light years away.... would someone exactly opposite the central axis of that triangle by 3 billion years on the other side, not measure a negative curvature? :hyper: If so, how does this describe the shape of the universe? Is the perception relative? If not, why not?

[Bobby]

Another universe, ours may be only one of an infinite number.

It seems to me that, If the Law of Conservation of Energy and Mass is true, then it is hard for me to see any alternative to what you have posted.

[Bobby]

Relative to what? If others don't exist within our spacetime, do they even exist relative to us and our universe? And if they exist within our spacetime, are they not just an extension of our own universe? If not, then galaxies could be considered other 'universes'. There was a time when we thought all the stars in the sky belongs to just our galaxy. When we discovered others beyond our own, we still included them within our own universe. If we discovered another larger body beyond what we consider our universe, would we then include it as part of the whole?

 

Brane theory predicts two 3-branes that collieded as the method of the beginning of our existence. So does it then predict another universe or is this other brane part of our universe? It is supposedly "within" a millimeter from us, but separated by dimensional constraints. So does the theory then say there is another universe that infuences our own, or that there's an extention of our own universe that we are out of phase with?

 

 

If others don't exist within our spacetime, do they even exist relative to us and our universe? =====> No, not without something to tie them together as you suggest that brane theory does.

[EWright]

ignore what was here; i thought i was responding to a different post

[Bobby]

Hi

 

As far as I understand it, the Universe has been expanding at the speed of light ever since the Big Bang. Which means that Space itself is expanding at the speed of light. The extremities of the Universe defines space, so to ask what is lying outside of it is meaningless. There is nothing, not even space. And there is no way of reaching it, seeing as the speed of light is a barrier we can't cross. So, yes - it's curved in on itself, but don't even try to imagine a 2 dimensional analogy for a 3 dimensional reality. You'll just pop a vein in your brain!

 

 

As far as I understand it, the Universe has been expanding at the speed of light ever since the Big Bang. Which means that Space itself is expanding at the speed of light. The extremities of the Universe defines space, so to ask what is lying outside of it is meaningless. There is nothing, not even space. And there is no way of reaching it, seeing as the speed of light is a barrier we can't cross.

 

Either there is something into which our Universe is expanding or there is not. If the answer is not, then it would seem that our Universe is expanding into nothingness, and nothingness is defined as the absence of existence.

 

So, yes - it's curved in on itself, but don't even try to imagine a 2 dimensional analogy for a 3 dimensional reality.

 

 

I doubt that the Universe folds back on itself, but that's just my opinion. The Universe could fold back on itself only if the Universe is closed rather than being flat or open.

[Bobby]

If we measure a positive curvature in space using the three stars, say roughly 3 billion light years away.... would someone exactly opposite the central axis of that triangle by 3 billion years on the other side, not measure a negative curvature? :) If so, how does this describe the shape of the universe? Is the perception relative? If not, why not?

 

 

If the measurements were influenced by gravity, and I think they would be, then any measurements you make would only be local measurements. I think measurements like this is what Einstein called a geometry, so the geometry of spacetime would depend on location in spacetime and would be different at different spacetime locations.

[EWright]

If the measurements were influenced by gravity, and I think they would be, then any measurements you make would only be local measurements. I think measurements like this is what Einstein called a geometry, so the geometry of spacetime would depend on location in spacetime and would be different at different spacetime locations.

 

True. Except measurements would not be 'influenced' by gravity; they would be dependent on it. We have gotten off topic regarding the 'edge of space' though. But then again, the geometry of space defines its shape. (There, we're back on topic.)

[Bobby]

True. Except measurements would not be 'influenced' by gravity; they would be dependent on it. We have gotten off topic regarding the 'edge of space' though. But then again, the geometry of space defines its shape. (There, we're back on topic.)

 

 

OK, OK, Don't get picky, that's what I meant. LOL.

 

I think gravity is very much on topic. Folks ask what is the shape of the Universe, what's on the other side, etc. It seems to me that if you explain how the shape of the Universe depends on gravity, then they can visualize a Universe filled with a gravitational field that and understand that the shape of the Universe depends on the mass located with the Universe.

[EWright]

OK, OK, Don't get picky, that's what I meant. LOL.

 

I think gravity is very much on topic. Folks ask what is the shape of the Universe, what's on the other side, etc. It seems to me that if you explain how the shape of the Universe depends on gravity, then they can visualize a Universe filled with a gravitational field that and understand that the shape of the Universe depends on the mass located with the Universe.

 

But the mass per unit of distance is diminishing as the universe expands at an accelerated pace.

[Bobby]

But the mass per unit of distance is diminishing as the universe expands at an accelerated pace.

 

I'll believe that the expansion rate is accelerating when I see pigs fly.

[EWright]

I'll believe that the expansion rate is accelerating when I see pigs fly.

 

Then I guess it'll be pretty hard to get an agreed upon consensus any time soon. I'll keep checking the evolution forum for evidence that pigs are developing wings.

 

Until then,

 

Oink, oink, flutter, flutter...

[Bobby]

Then I guess it'll be pretty hard to get an agreed upon consensus any time soon. I'll keep checking the evolution forum for evidence that pigs are developing wings.

 

Until then,

 

Oink, oink, flutter, flutter...

 

 

Evolution? What's that? My parents didn't come from apes. they came from Kentucky.

[EWright]

Evolution? What's that? My parents didn't come from apes. they came from Kentucky.

 

LOL. OK, so you don't believe in *accelerated* expansion of the universe. But I take it you do believe the universe is expanding? Gravitational force of the universe is then still being diminished per unit of distance.

[Bobby]

LOL. OK, so you don't believe in *accelerated* expansion of the universe. But I take it you do believe the universe is expanding? Gravitational force of the universe is then still being diminished per unit of distance.

 

Yep. And if you used clocks in a gravity free region as a reference, the thinning out of the Universe would make clocks run faster and clocks in the past would have run slower. Put these together and you get (mathematically) an accelerating rate of expansion.

[EWright]

Yep. And if you used clocks in a gravity free region as a reference, the thinning out of the Universe would make clocks run faster and clocks in the past would have run slower. Put these together and you get (mathematically) an accelerating rate of expansion.

 

 

Mathematically, visually, and actually....

[sinewave]

How can an infinitely random space, at any scale, have an 'edge'?

 

illogical

[EWright]

How can an infinitely random space, at any scale, have an 'edge'?

 

illogical

 

Not everyone agrees that it's infinite, and there are good arguments against it being so. And what's so 'random' about it (considering it's amazing uniformity)?