The Expanding Universe: Quick question

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Sanjuricus
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The Expanding Universe: Quick question

Postby Sanjuricus » Wed Oct 26, 2011 11:09 am UTC

Hi All,
Had a thought the other day while listening to the full length theme song from Big Bang Theory...

I know its almost impossible to do in real terms and with current understanding...these questions are hypothetical really....but anyway, supposing you were able to go out into space and simply stop. By stop I mean to hold your present absolute position relative to the rest of the universe, the only dimension you move through is time. If you were able to do this, how fast would nearby objects appear to move? I would imagine that it would be pretty quick.

Now imagine that whatever absolutely stationary vehicle you are in exists in a universe where the big crunch is the way its all gonna end...that means that at some point in the distant future, the universe will, at the very least for an instant, be absolutely still. I'm not on about the stuff within the universe...but the universe itself. How would that look to an observer aboard this stationary craft? I assume red shift and blue shift would be eliminated (ignoring for the moment the time it would take the light to get there) and it would be kinda eerie and creepy, possibly with some atmospheric music playing in the background...

Just a whimsical question. :)
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Re: The Expanding Universe: Quick question

Postby thoughtfully » Wed Oct 26, 2011 11:28 am UTC

Sanjuricus wrote:I know its almost impossible to do in real terms and with current understanding...

Not almost, entirely impossible. There is no preferred reference frame for you to park in.

a universe where the big crunch is the way its all gonna end...that means that at some point in the distant future, the universe will, at the very least for an instant, be absolutely still.

Nope. Spacetime does the expanding and contracting, the matter in the Universe will keep moving merrily along. To do otherwise would be a violation of Conservation of Momentum.
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Re: The Expanding Universe: Quick question

Postby Tass » Wed Oct 26, 2011 1:00 pm UTC

Let me elaborate on thoughtfully's answers. Nothing in the universe is moving as a direct result of the big bang (sure things are moving here and there with relatively small velocities, that is called that things peculiar velocity). Big bang was not an explosion. It didn't happen at a particular point, with everything moving away from that point. It happened everywhere. You could say it still happens everywhere. Everywhere is simply getting bigger. There is becoming more and more space in between things, without anything actually moving. So if you move to some other place in the universe and then stop relative to the big bang (or the next best thing, which we can actually measure the cosmic microwave background) then it would look pretty much like it looks here: Stars and galaxies, the far away ones redshifted and getting further away by the second.

Same thing with the big chrunch. You won't be able to stand somewhere and watch every thing crash together to a point over there. Everywhere is the point it converges on.

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Re: The Expanding Universe: Quick question

Postby Bears! » Wed Oct 26, 2011 3:04 pm UTC

Tass wrote:Same thing with the big chrunch. You won't be able to stand somewhere and watch every thing crash together to a point over there. Everywhere is the point it converges on.


*head explode*

Can you give me a way to visualize this? It sounds so crazy, but I suspect that it isn't as head-explodey as it seems.
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Re: The Expanding Universe: Quick question

Postby LaserGuy » Wed Oct 26, 2011 3:32 pm UTC

Bears! wrote:
Tass wrote:Same thing with the big chrunch. You won't be able to stand somewhere and watch every thing crash together to a point over there. Everywhere is the point it converges on.


*head explode*

Can you give me a way to visualize this? It sounds so crazy, but I suspect that it isn't as head-explodey as it seems.


Here's the 2-D version. The 3-D version isn't as intuitive to visualize, but the basic principles are the same.

Suppose that you're an ant standing on a balloon. You want to move from point A to point B. While you are walking from one point to the other, taking a rest at Point C, when somebody starts inflating the balloon without your knowledge. What do you see? Well, nothing is happening to point C where you're standing, as far as you can tell. But both point A and point B are moving away from you. If you look in all directions, you'll see that everything is moving away from you simultaneously. But there's nothing special about the point C. If you were standing at point A, everything would appear to be moving away from you in all directions. Ditto if you were at point B. The Big Crunch works basically the same, except that the balloon is being deflated.

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Re: The Expanding Universe: Quick question

Postby Sanjuricus » Wed Oct 26, 2011 3:51 pm UTC

Can someone call an ambulance...my brain has just exploded....seriously, it's all over my monitor!!!
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Re: The Expanding Universe: Quick question

Postby Anaphase » Wed Oct 26, 2011 5:10 pm UTC

LaserGuy wrote:
Bears! wrote:
Tass wrote:Same thing with the big chrunch. You won't be able to stand somewhere and watch every thing crash together to a point over there. Everywhere is the point it converges on.
*head explode*Can you give me a way to visualize this? It sounds so crazy, but I suspect that it isn't as head-explodey as it seems.
Here's the 2-D version. The 3-D version isn't as intuitive to visualize, but the basic principles are the same.

Suppose that you're an ant standing on a balloon.

Sorry, that's not head-explodey enough. :P
Last edited by Anaphase on Wed Oct 26, 2011 7:38 pm UTC, edited 1 time in total.

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Re: The Expanding Universe: Quick question

Postby Xanthir » Wed Oct 26, 2011 7:12 pm UTC

Thanks for that, Anaphase! That's a really awesome page. It explains really well (as it summarizes at the very end) the difference between "we consider space as curved because that happens to be how we measure the coordinates" and "space is curved because of gravity, that's that".
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Sanjuricus
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Re: The Expanding Universe: Quick question

Postby Sanjuricus » Wed Oct 26, 2011 8:02 pm UTC

Xanthir wrote:Thanks for that, Anaphase! That's a really awesome page. It explains really well (as it summarizes at the very end) the difference between "we consider space as curved because that happens to be how we measure the coordinates" and "space is curved because of gravity, that's that".

Ditto from me. page bookmarked for digestion later. :)
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Re: The Expanding Universe: Quick question

Postby Aelfyre » Wed Nov 02, 2011 3:39 pm UTC

LaserGuy wrote:
Bears! wrote:
Tass wrote:Same thing with the big crunch. You won't be able to stand somewhere and watch every thing crash together to a point over there. Everywhere is the point it converges on.


*head explode*

Can you give me a way to visualize this? It sounds so crazy, but I suspect that it isn't as head-explodey as it seems.


Here's the 2-D version. The 3-D version isn't as intuitive to visualize, but the basic principles are the same.

Suppose that you're an ant standing on a balloon. You want to move from point A to point B. While you are walking from one point to the other, taking a rest at Point C, when somebody starts inflating the balloon without your knowledge. What do you see? Well, nothing is happening to point C where you're standing, as far as you can tell. But both point A and point B are moving away from you. If you look in all directions, you'll see that everything is moving away from you simultaneously. But there's nothing special about the point C. If you were standing at point A, everything would appear to be moving away from you in all directions. Ditto if you were at point B. The Big Crunch works basically the same, except that the balloon is being deflated.


OK there are alot of universe expanding threads out there so rather than start another I will use this example to ask my question. :)

The balloon example is a perfect way to visualize my idea.. it basically deals with The Holographic Principle.

If we were to assume for a minute that the universe really was a 3 dimensional representation of occurances on a 2 dimensional boundary lair, would it then be logical to conclude that it might be possible for space to appear to expand in all directions if the membrane itself were vibrating or pulsing?

We see it expanding now and accelerating but perhaps that is because we have such a small data set to work with of past observations.. just a few decades in a time frame of trillions of years..

perhaps we are in an accelerating phase of the universe but it will in fact slow at some point as the membrane reaches the peak or trough of its frequency and then reverse itself and everything will come rushing together again regardless of its relative velocity until it is all squeeze back into a singularity and then ripped apart again into another quark-gluon mixture which then reforms into matter-antimatter, annihiliates, ashes are left over which condense into matter which becomes hydrogen which collapses and forms other elements etc etc and the whole process begins again with the slate wiped clean and a brand new universe full of hydrogen gas clouds?

I guess the question is, in a holographic universe could the "space" of the representation be affected by changes in the "shape" of the membrane?
Xanthir wrote:To be fair, even perfectly friendly antimatter wildebeests are pretty deadly.

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Re: The Expanding Universe: Quick question

Postby Anaphase » Wed Nov 02, 2011 10:25 pm UTC

The membrane is a mathematical idea, it isn't a physical thing. The idea as I understand it is that the mostly empty three-dimensional space we inhabit can be mapped consistently onto a much more crowded two dimensional space.

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Re: The Expanding Universe: Quick question

Postby Aelfyre » Thu Nov 03, 2011 12:44 pm UTC

Anaphase wrote:The membrane is a mathematical idea, it isn't a physical thing. The idea as I understand it is that the mostly empty three-dimensional space we inhabit can be mapped consistently onto a much more crowded two dimensional space.



I think calling it an idea vs a physical thing is just semantics really. My question still stands that if we were to assume that this membrane (real or conceptual) is vibrating or oscillating in some manner could it possible cause perceived expansion/contraction of physical space in our universe?
Xanthir wrote:To be fair, even perfectly friendly antimatter wildebeests are pretty deadly.


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