The "Symmetrical Expansion" of Space

[Physman]

As research and collected data have confirmed the Universe is most likely in an expansion phase. When we imagine the expansion fo the Universe we see an origin or center and then an infinite expansion in all 3d (4d/ Space time). My question is: are all sides of the expansion of the universe symmetrical? To rephrase, Considering a 3d circle expansion (sphere) will the radius of the finite or infinite system be the same in all positions or vary?

[iNow]

I think your question is flawed, as it seems to assume that the universe has a center (I get this specifically from your mention of a radius). The universe is expanding in all directions, no matter from where you are looking. As you go out farther away from any spot (from any point whatsoever) the rate of expansion increases the further out you go.

 

Also, the universe is flat, not spherical, so there's always that.

 

I'm not sure if this helps or not. That's just what jumped out at me after reading your OP.

[toastywombel]

As research and collected data have confirmed the Universe is most likely in an expansion phase. When we imagine the expansion fo the Universe we see an origin or center and then an infinite expansion in all 3d (4d/ Space time). My question is: are all sides of the expansion of the universe symmetrical? To rephrase, Considering a 3d circle expansion (sphere) will the radius of the finite or infinite system be the same in all positions or vary?

 

The reason we know that the galaxies and super-clusters are moving apart from each other is because they are red-shifted and galaxies further apart are red-shifted even further, but we don't exactly know where the center is or if there is a center. I do not think we can pin point a center, all we know is that the other galaxies are moving away from our Milky Way Galaxy (there are some exceptions though, Andromeda is on a course for our galaxy), and the further away the galaxies are, the faster they are moving away from us.

 

As far as imagining the Universe as a 3d circle with a definite radius, that is not necessarily a good way of thinking of it. Stephen Hawking explains it well in his book a Brief History of Time and of course I am paraphrasing.

 

The Universe has no boundaries but is finite. Think of it being a two dimensional observer moving around the surface of a three dimensional sphere. You could never reach the end, and it would seem limitless but its really not, there is a finite amount of surface area.

 

Just like how the two dimensional observer is limited in what he/she can see in a three dimensional universe, we three dimensional observers are limited in what we can see in our four, ten, or twenty dimensional Universe.

 

The reason why I say four, ten or twenty is because there are different versions of string theory that theorize different values for how many dimensions our Universe is made up of.

 

Finally Mr. INow mentioned how the Universe is flat, that is correct and to expand upon it, It may not seem flat to us because we can look up, down, right, left, front, and back, but just like how a two dimensional object looks flat when viewing it from a three dimensional perspective a three-dimensional object might look flat when viewing it from a four, dimensional perspective and it may look like just a dot from even higher dimensions. Of course no-one knows for sure, but I find looking at it this way helps me understand these theories.

 

Stephen Hawking also said in his other book Universe in a Nutshell (which I liked a little more than the latter) that no single man can completely understand the implications of quantum mechanics. So don't feel discouraged if it is hard to grasp.

 

It is hard to imagine but I hope I helped .

Edited October 23, 2009 by toastywombel

[J.C.MacSwell]

All that said, there is a symmetry apparent in the expansion, even in all directions, measured from points at rest with respect to the CMBR.

 

This symmetry changes when moving with respect to the CMBR.

[Physman]

tell me this, did or did not, the Big Bang have a postion on space? If your answer is yes, then you have just named a "center." Even if the universe is flat it could still have a symmetrical expansion.

[toastywombel]

tell me this, did or did not, the Big Bang have a postion on space? If your answer is yes, then you have just named a "center." Even if the universe is flat it could still have a symmetrical expansion.

 

I assume you mean the point of singularity. No it did not have a point in space, all space was existent within that point, space expanded with universe after the big bang.

[iNow]

tell me this, did or did not, the Big Bang have a postion on space?

 

Physman... I hate to sound like a broken record, but this is yet another flawed approach. This question is entirely meaningless.

 

The BB did not have a "position on space." The BB was the expansion of space itself... Everywhere and everything was expanding... not merely some point within it as you seem to suggest.

 

Your question assumes something akin to a drop of ink into a pitcher of water. There is no pitcher of water. All that exists is the ink itself. It's not expanding into anything, and it had no position. The concept of position is meaningless in this sense since there is nothing by which to compare it. The universe is EVERYTHING. There is no "outside" the universe, and there is no center (or, conversely, all points within the universe are its center... whichever you prefer, they are essentially equivalent).

[toastywombel]

Physman... I hate to sound like a broken record, but this is yet another flawed approach. This question is entirely meaningless.

 

The BB did not have a "position on space." The BB was the expansion of space itself... Everywhere and everything was expanding... not merely some point within it as you seem to suggest.

 

Your question assumes something akin to a drop of ink into a pitcher of water. There is no pitcher of water. All that exists is the ink itself. It's not expanding into anything, and it had no position. The concept of position is meaningless in this sense since there is nothing by which to compare it. The universe is EVERYTHING. There is no "outside" the universe, and there is no center (or, conversely, all points within the universe are its center... whichever you prefer, they are essentially equivalent).

 

Nice analogy with the pitcher of water. Thank you for confirming what I said , I am always somewhat unsure of myself when it comes to explaining these concepts accurately .

[J.C.MacSwell]

I assume you mean the point of singularity. No it did not have a point in space, all space was existent within that point, space expanded with universe after the big bang.

 

I don't think it is currently accepted as being a point, or even finite. It may have been infinite in expanse, yet very, very dense, and expanded from that.

[iNow]

Just to add to that... Few (if any) serious cosmologists really think the universe ever existed in a singularity state. The predominant (AFAIK) viewpoint is that the singularity is merely an artifact of our math... That our models are not yet honed enough to adequately describe the situation. The same thing applies to the center of blackholes. Most people working on the idea don't think that the center is really a singularity. It's just that the math we use which works so well in other reference frames tends to break down at these levels (early universe, center of BH, etc.)... not that those points are truly singularities.

 

So, the math shows singularities, but most think that the math is limited and needs further work, not that the universe actually existed itself as a singularity.

[toastywombel]

Just to add to that... Few (if any) serious cosmologists really think the universe ever existed in a singularity state. The predominant (AFAIK) viewpoint is that the singularity is merely an artifact of our math... That our models are not yet honed enough to adequately describe the situation. The same thing applies to the center of blackholes. Most people working on the idea don't think that the center is really a singularity. It's just that the math we use which works so well in other reference frames tends to break down at these levels (early universe, center of BH, etc.)... not that those points are truly singularities.

 

So, the math shows singularities, but most think that the math is limited and needs further work, not that the universe actually existed itself as a singularity.

 

True but there is no way to prove it either way yet, I just used "point of singularity" because he was referring to that point as the center of the Universe. Good to point that out though

[asprung]

If the universe (not space) started as a singlularty and expands uniformly it must have a center or central point.

[Sorcerer]

I think your question is flawed, as it seems to assume that the universe has a center (I get this specifically from your mention of a radius). The universe is expanding in all directions, no matter from where you are looking. As you go out farther away from any spot (from any point whatsoever) the rate of expansion increases the further out you go.

 

Also, the universe is flat, not spherical, so there's always that.

 

I'm not sure if this helps or not. That's just what jumped out at me after reading your OP.

 

You can only assume this. All we can say is that from where we observe the universe is uniformally expanding. AND then assume that the universe is the same everywhere as from where we observe. Occams razor would have that be correct.

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All that said, there is a symmetry apparent in the expansion, even in all directions, measured from points at rest with respect to the CMBR.

 

This symmetry changes when moving with respect to the CMBR.

 

Sorry for being redundant. I should read b4 I post.

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Consecutive posts merged

Center in 3D or 4D?

Edited November 7, 2009 by Sorcerer
Consecutive posts merged.

[iNow]

You can only assume this. All we can say is that from where we observe the universe is uniformally expanding. AND then assume that the universe is the same everywhere as from where we observe. Occams razor would have that be correct.

 

Nonsense.

http://en.wikipedia.org/wiki/Metric_expansion_of_space#Observational_evidence

 

 

 

Sorry for being redundant. I should read b4 I post.

QFT

[j_rankin]

I don't see what the big question is.

 

If you drew a circle, and then drew a line coming out of the centre of the circle at 1 degree at the same time as you drew a line coming out at 2 degrees, then both lines would keep getting further and further apart, quicker and quicker. Thus each galaxy getting further and further away quicker and quicker (except the most local galaxies).

 

If the universe started with the big bang, then galaxies formed after the re-ionisation period and began their outward journey. Gravitic affects would have then come into play and kept galaxies in clusters as they moved out through space.

[radienx000]

Well this could only be true if the Big Bang did existed. But if everything started from one point, than wouldn't everything evolve into the same thing? Cause from one point in space, if it were to expand, then everything on the two ends of the point, would be symmetrical and so everything would end up being the same thing because it started from the same point. Understandable??

[j_rankin]

"" Well this could only be true if the Big Bang did existed. But if everything started from one point, than wouldn't everything evolve into the same thing? Cause from one point in space, if it were to expand, then everything on the two ends of the point, would be symmetrical and so everything would end up being the same thing because it started from the same point. Understandable?? ""

 

Well, that's where quantum physics comes in, because as soon as particles get created, they all behave in chaotic ways.

During the first few hundred million years after the big bang, it is believed that the universe was an intense flurry of superheated particles. Many of these particles would follow quantum rules, which would mean the universe would form with a random distribution and when many particles randomly got dumped near each other they began creating gravity.

Edited November 9, 2009 by j_rankin

[ponderer]

"" Well this could only be true if the Big Bang did existed. But if everything started from one point, than wouldn't everything evolve into the same thing?

 

No. As soon as you quantize energy into interacting particles, or wavicles, massive or otherwise, you have created a dynamic system.

 

Chaos theory, which has mathematics describing the behaviour of dynamic systems, has an unfortunate name. That is because clustering and structure arise according to the mathematics of dynamic systems, described by Chaos theory.

 

Chaos might be seen to be the antithesis of entropy.

 

While entropy tends to homogenize energy density, and errode structure, Chaos tends to localize energy density in a chaotically structured manner.

 

The structure you see around us is governed by chaos theory mathematics. The main themes are fractals, bifurcations, and strange attractors. Bifucations occur in population densities for example, where you get gradual change suddenly interrupted by an event, which causes a sudden dramatic increase or decrease in population. Strange attractors are things like galaxies, solar systems, the red spot on Jupiter, and closer to home, such things as the shapes of plants, turbulance, clouds, mountains, shorelines, errosion valleys, the course of rivers, etc.

 

The genernation of some strange attractors involves fractal math, and others involve phase space.

 

You immediately recognize the classification of the thing you are seeing, and can put a name to it, but no two are exactly alike.

Edited February 14, 2010 by ponderer