Where Is The Center Of The Big Bang Universe?

[mijopaalmc]

Good point. Perhaps gluing grains of sand onto the balloon would be even better.

There's always the raisin bread cosmology.

 

[Olowkow]

I wonder if this works, I am open to a flat out "NO":

Imagine a really huge airplane hangar which is undergoing a gas explosion. There are 10 ton lead blocks (galaxies) sitting around in the hangar. The space inside the hanger increases as the walls are blown out, but the lead blocks pretty much stay in place, but may move slightly, because of their mass, and they do not come apart like less massive objects in the hangar. Further, the floor also expands slightly due to the explosion, so the lead blocks that are far apart to begin with, are now separated more than than the ones that had been closer to each other before, because the floor expands at a constant rate.

The lead blocks are not greater in volume after the explosion, but they may be slightly further apart in the case of those that were far apart to begin with, than those that were right next to each other.

One really needs to remind onself that the universe is really, really, big.

 

[Tubbythin]

I wonder if this works, I am open to a flat out "NO":

Imagine a really huge airplane hangar which is undergoing a gas explosion. There are 10 ton lead blocks (galaxies) sitting around in the hangar. The space inside the hanger increases as the walls are blown out, but the lead blocks pretty much stay in place, but may move slightly, because of their mass, and they do not come apart like less massive objects in the hangar. Further, the floor also expands slightly due to the explosion, so the lead blocks that are far apart to begin with, are now separated more than than the ones that had been closer to each other before, because the floor expands at a constant rate.

The lead blocks are not greater in volume after the explosion, but they may be slightly further apart in the case of those that were far apart to begin with, than those that were right next to each other.

One really needs to remind onself that the universe is really, really, big.

I might have misunderstood what you mean, but your analogy seems to lack the necessary isotropy.

 

[Skeptic Ginger]

I have to chime in with my revelation. Of course it will be a while before my genius is recognized.

The past is the center and the future is the edge. After all, we are supposed to understand this as a 4 (at least) dimensional Universe. Of course you can't find the center and edge if you only look at 3 dimensions.

 

[Olowkow]

I might have misunderstood what you mean, but your analogy seems to lack the necessary isotropy.

I'm still working on that.... though a "gas" explosion sort of woofs in all directions at the same time, I think. I was trying to address the problems some are having with "space" expanding, but galaxies and smaller massive structures don't, being gravitationally bound.

 

[articulett]

Sol's answer is a good one, but here's a way to illustrate it for yourself.

Get a balloon and a marker. Place some dots on the outer surface of the balloon. The balloon's outer surface represents the spacetime fabric of our universe, and the dots represent galaxies and galaxy clusters. You can even mark one dot with MW for Milky Way (our galaxy).

Now, slowly inflate the balloon and observe what happens. From the point of view of MW, all the other galaxies and clusters appear to move away -- likewise, from the point of view of another galaxy, the MW and all others would appear to move away. So, the idea is that no matter where you are in the universe, you will observe everything to be stretching away from you and could easily conclude that you're at the "center".

This is an illustration of what's known as the Cosmological Principle.

Two important points to note about this example:

1. People will often ask, "What's inside the balloon? Isn't that where the 'center' is?"

The answers are "nothing" and "no." Remember that in this model the entire universe is the stretched fabric of the outer surface of the balloon. The question of what's "inside" isn't relevant, unless you wish to speculate about hypothetical extra dimensions of space, etc.

2. Note that the dots on your balloon do not actually move along the surface of the balloon; rather they move with the balloon's surface as it stretches. In addition, dots further from the MW dot will appear to stretch away faster than nearby ones.

This points out a common misconception about big bang cosmology: that galaxies and galaxy clusters are actually moving through space. They aren't (for the purposes of an expanding universe, that is), instead they are being carried along with the spacetime fabric of the universe as it is undergoing an expansion or stretching.

Lastly, about the further points moving faster as compared to the closer ones: this is an illustration of Hubble's Law, which was one of the first ways we quantified the age of the universe to be many billions of years (roughly 13.7 billion years by current estimates).

I hope this helps. Have fun with your balloons!

Most excellent explanation! Thanks.

 

[Skeptic Ginger]

Here everyone is using a 2 dimensional model, the balloon surface, because they cannot describe no center and no edge in a 3 dimensional model, yet we are not in a 2 dimensional space and we are not certain that, if you went in one direction forever you'd pass by the place you left or not.

Of course, what do you do with the 3 dimensions in my 4 dimensional model of past time being toward the center and future time being the edge?

The problem with both models is we cannot answer how the large scale Universe theory fits the small scale 3 dimensional world we observe.

 

[articulett]

Well you can always do what woo do and use this lack of understanding as proof that your woo is true.

 

[MattusMaximus]

Most excellent explanation! Thanks.

You're welcome. I must say that this has been a particularly productive thread, with much good science represented by those posting, and (so far) a distinct lack of woo

 

[INRM]

So it's like a bubble, but it's expansion is sort of "inverted". It expands from the outside, forcing the inside to expand within the outside? Why does that happen, and not from a central point?

Is this expansion pattern indicative of the universe expanding as a result of a vacuum-quantum fluctuation? (It would defy the conservation of mass/energy law as it's definetly existed long enough to be observed, to my knowledge and wouldn't other fluctuations have occured as well? I mean generally doesn't it generally work that if one particle disappears another one appears somewhere else?)
Also, how does something not violate the mass energy law if two particles of equal mass appear, and disappear and a single particle of the same mass as one of the two previous particles appear within planck time? I mean they did exist right?

Most modern theories point to the universe being mostly planar? How does this happen? Generally the natural shape things tend to take in nature is a sphere or a flattened sphere (not quite a ball, but not quite a pancake either)

Regarding the statement of the universe reaching a peak size and then imploding. Would that be it and existance would just end? Or would that end up resulting in a big-bang and so on?


INRM

 

[baron]

That's the best analogue anyone has come up with - to be more precise, we would need math.

Yep, that's probably the issue. The balloon analogy works up to a point. Pity I don't have the maths experience!

 

[sol invictus]

So it's like a bubble, but it's expansion is sort of "inverted".

No.

It expands from the outside, forcing the inside to expand within the outside?

Inside? Outside?

Remember, the surface of the balloon is the universe. There's no inside or outside.

Is this expansion pattern indicative of the universe expanding as a result of a vacuum-quantum fluctuation?

No.

Also, how does something not violate the mass energy law if two particles of equal mass appear, and disappear and a single particle of the same mass as one of the two previous particles appear within planck time? I mean they did exist right?

Energy is always conserved. Temporary quantum fluctuations can produce pairs of particles, but one always has negative energy and so the total energy is zero.

People have speculated about the universe beginning as a quantum fluctuation of various sorts, but there is no theory that can really handle that.

Most modern theories point to the universe being mostly planar?

Observations plus general relativity tell us that our part of the universe is pretty flat (meaning the three dimensional spatial curvature is close to zero).

How does this happen? Generally the natural shape things tend to take in nature is a sphere or a flattened sphere (not quite a ball, but not quite a pancake either)

Inflation. http://en.wikipedia.org/wiki/Cosmic_inflation

Regarding the statement of the universe reaching a peak size and then imploding. Would that be it and existance would just end? Or would that end up resulting in a big-bang and so on?

No one knows. Probably the former.

 

[INRM]

Sol Invictus,

What evidence suggests that if the universe imploded into a big crunch existence would end and there would be nothing?

 

[MattusMaximus]

Energy is always conserved. Temporary quantum fluctuations can produce pairs of particles, but one always has negative energy and so the total energy is zero.

Something lurkers should note is that this business of quantum fluctuations, vacuum energy, and virtual particles has been experimentally confirmed. Check out this link on the Casimir Effect for more info.

 

[MattusMaximus]

I can't remember who it was, but someone on the thread was asking about where the universe is going in reference to expanding spacetime. As has already been mentioned, one possible outcome is a closed (or bound) universe, which would probably lead to a Big Crunch.

There are two other possibilities that I know of:

1. Heat Death -- this is where the universe basically continues to expand, with the internal gravity slowing down the rate of expansion but never overcoming and reversing it. Essentially, as the universe continues to expand, matter slowly gets more and more spread out, with galaxies no longer being able to see one another because they're beyond each other's Hubble limit. At a ludicrous amount of time in the future, even stars wouldn't be able to see one another anymore; stellar formation would eventually cease and everything would cool down to an equilibrium, thereby maximizing the entropy of the universe. This would occur in a flat or open (unbound) geometry.

2. Big Rip -- in this scenario, the dark energy which is now driving the universe expansion more than gravity is fighting it would continue to drive galaxies and clusters further apart. Much of what follows would be like Heat Death, except that (depending upon the value of the cosmological constant) eventually the repulsion of dark energy would get so strong that galaxies, stars, planets, and even atoms would be ripped asunder by the enormous acceleration of expanding spacetime.

I'm not sure exactly which scenario is most likely at this stage, but with the information that we currently have I think the Big Crunch is out.

 

[edd]

Something like the heat death you describe is the most likely one, and your description of the big rip is a bit off. The big crunch is pretty much out (you'd have to come up with some weird variety of dark energy that ultimately vanished or went negative or something, and we've no reason to think that would ever be the case).

Big rip scenarios only happen with phantom energy, a variety of dark energy that grows in density as the universe expands. It can't happen with a cosmological constant which stays constant as the universe expands - that never becomes strong enough to rip apart bound systems.

In the cosmological constant case the universe continues to expand ever faster, and you get what happens in your heat death description except that the rate doesn't slow, it speeds up.

Also, the geometry is not related to the ultimate fate of the universe. It is only related in the specific case of a universe with no dark energy. Closed universes with dark energy can have a heat death and never recollapse.

 

[AkuManiMani]

Where Is The Center Of The Big Bang Universe?

Everywhere.

 

[Yllanes]

I can't remember who it was, but someone on the thread was asking about where the universe is going in reference to expanding spacetime. As has already been mentioned, one possible outcome is a closed (or bound) universe, which would probably lead to a Big Crunch.

There are two other possibilities that I know of:

John Baez has a very interesting page (non technical) on the fate of the universe at really long time scales.

 

[RecoveringYuppy]

For some reason I was expecting that page to be very interesting because it would all be explained in folk songs.

 

[shadron]

OK, guys. What does this add to the discussion?

http://apod.nasa.gov/apod/ap080309.html