Where is the center of the universe?

[JediSouth]

I have a question. I have been watching a lot of docs about cosmology and the origin of the universe, and seems that most agree that it began with inflation. I believe this, but what gets me is this. Where is the center of the beginning of this inflation? And, if the universe is expanding exponetionly, then how do we know that when we look far out in the sky, that we are looking in the right direction? If everything is moving away from everything else, then there has to be a point at which it all started...which would be the center of creation. Everything would have expanded away from that point.
That makes sense to me. The only thing I am asking is this. If we look in one direction, and supposely what we see, is what is at that vast distance, because of the time it took for that light to get here, would mean we are looking at the beginning of existence. But, what if we look in the opposite direction? Of course, things would always be moving away from each other, but what i can't figure out is this. We are lookiing at at those vast distances,and they show the beginning of creation, because of the distance it takes for that light to reach us, but how, the beginning of creation should only be seen by looking in the direction of the origin of creation, which would mean we would have to be looking towards some center of where it all started. How do we know that we are looking at the beginning of time when what are are analising at those millions of light years away is what has traveled AWAY from some center. It's a paradox to me. Why, just because the light we see took billions of years to get here, that that is the beginning of time, wouldn't the beging of time only be visible by lookin in the direction of the origin of it? There must be a center right? from which inflation began.
I don't know. I am not a physics prof but I am absolutely fascinated by these things and i understand the conceptual theories, just not the math. That gives me a disadvantage. But it defeinatly intrigues me
If anyone has a theory of this, I'd like to hear it please
thanks

New guy with lots of thoughts...lol

 

[russ_watters]

Welcome to PF. Imagine sitting on a high mountain. Turn around in every direction - in every direction, the Earth looks roughly the same. This is a good 2d analogy for the 3d space.

Everywhere we look in space, it looks about the same. This implies rather strongly that there is no center to the universe. And expansion need not require one: replace the Earth with a giant balloon, expanding, and the analogy still holds.

 

[Chronos]

The CMB [cosmic microwave background] intensity is virtually identical in all directions as viewed from earth. This would not be possible unless Earth happens to be very near the 'center' of the universe. Given Earth is not the center of the solar system, is vastly distant from the center of our galaxy, and not even close to the center of the local group of galaxies, the proposition appears hugely improbable. See, for example, http://www.astro.ucla.edu/~wright/cosmo_01.htm

 

[IanTBlack]

I'm going to have to agree with JediSouth. The implications are strong that there is not really a center of the universe. Imagine you are on a lake and if you look around you don't see any shore. How is it possible to know if you are in the center?

Also, when something is spinning, that doesn't mean that the object is spinning on its center axis. The point where the object is spinning is the spin center, but not the object center. What I'm trying to say is that you can't decipher an objects center through its spin.

Yet if we go with the Big Bang Theory and assume that during the moment when everything was at a single point and then it exploded, that the single point would have been the center of the universe and would still be. Although the expansion of the universe would beg to differ. Some parts probably expand faster than others. Therefore, the universe is more of and amoeba and does not have a center.

Just some thoughts.

 

[HallsofIvy]

I have a question. I have been watching a lot of docs about cosmology and the origin of the universe, and seems that most agree that it began with inflation. I believe this, but what gets me is this. Where is the center of the beginning of this inflation? And, if the universe is expanding exponetionly, then how do we know that when we look far out in the sky, that we are looking in the right direction? If everything is moving away from everything else, then there has to be a point at which it all started...which would be the center of creation. Everything would have expanded away from that point.

This argument is not correct. If every object in the universe got farther away from its nearest neighbot, that would be "expanding"- but there would not be, and there does not have to be a "center" of expansion.

Yet if we go with the Big Bang Theory and assume that during the moment when everything was at a single point and then it exploded, that the single point would have been the center of the universe and would still be. Although the expansion of the universe would beg to differ. Some parts probably expand faster than others. Therefore, the universe is more of and amoeba and does not have a center.

Just some thoughts.

As far as your "amoeba" analogy is concerned, I agree. But you are incorrect that the Big Bang occurred at a single point. There was no space before the big bang. It is correct to say, rather, that every point in the current universe was the point where the big bang occurred.

 

[IanTBlack]

So what you are saying is that every point is the center?

 

[Lok]

So what you are saying is that every point is the center?

Space does not need to have been created at the big bang, and we will never know. So this concept of every point being a center is a theory.

Just one of many theories that may or may not hold water. All try to explain a few unexplained things about or universe, mainly to this thread is the average matter density of our observable universe which is rather constant anywhere we look, and the accelerated expansion ( with mystical dark matter & energy theories).

 

[Nickelodeon]

Welcome to PF. Imagine sitting on a high mountain. Turn around in every direction - in every direction, the Earth looks roughly the same. This is a good 2d analogy for the 3d space.

Everywhere we look in space, it looks about the same. This implies rather strongly that there is no center to the universe. And expansion need not require one: replace the Earth with a giant balloon, expanding, and the analogy still holds.

I never feel comfortable with the expanding balloon analogy because in this case the centre of the balloon would be the origin of expansion.
Also, the thought occurs that more than likely we are not be able to see the entire universe (Hubble horizon??) and so are not in a position to determine if the receeding acceleration and direction (edit .. of the distant galaxies) points to a preferred area.

 

[russ_watters]

I never feel comfortable with the expanding balloon analogy because in this case the centre of the balloon would be the origin of expansion.

That's a misreading of the analogy: the center of the balloon is not a point on the surface of the balloon.

Also, the thought occurs that more than likely we are not be able to see the entire universe (Hubble horizon??) and so are not in a position to determine if the receeding acceleration and direction (edit .. of the distant galaxies) points to a preferred area.

The other galaxies we see and the CMB provide such a dreference.

 

[JediSouth]

This argument is not correct. If every object in the universe got farther away from its nearest neighbot, that would be "expanding"- but there would not be, and there does not have to be a "center" of expansion.


As far as your "amoeba" analogy is concerned, I agree. But you are incorrect that the Big Bang occurred at a single point. There was no space before the big bang. It is correct to say, rather, that every point in the current universe was the point where the big bang occurred.

Yeah, but how would that be possible? if every point was a center than that would mean we are in multiverses. maybe like a fabric of some kind resembling the way the physics of atoms work only in a larger scale.

 

[JediSouth]

This argument is not correct. If every object in the universe got farther away from its nearest neighbot, that would be "expanding"- but there would not be, and there does not have to be a "center" of expansion.


As far as your "amoeba" analogy is concerned, I agree. But you are incorrect that the Big Bang occurred at a single point. There was no space before the big bang. It is correct to say, rather, that every point in the current universe was the point where the big bang occurred.

I never feel comfortable with the expanding balloon analogy because in this case the centre of the balloon would be the origin of expansion.
Also, the thought occurs that more than likely we are not be able to see the entire universe (Hubble horizon??) and so are not in a position to determine if the receeding acceleration and direction (edit .. of the distant galaxies) points to a preferred area.

Exactly! There would have to be a center of that ballooon.

 

[russ_watters]

Exactly! There would have to be a center of that ballooon.

No.

Ignoring the meaning of the analogy does not make it go away. You must deal with the analogy as it is actually worded/defined. Otherwise, you're just arguing against a point that doesn't exist.

 

[CosmicCrunch]

idk i i think when people use the balloon analogy there stating that the universe is stretching, not expanding

 

[IanTBlack]

The balloon analogy also makes it seem as if the universe is expanding at roughly the same rate. It isn't. Some parts go faster than others.

 

[Fredrik]

Jedi, Ian, Nick...There must be hundreds of these threads already. If you do a search, you will find hundreds of answers to your questions. Some of them bad, but the ones given by people with science advisor or mentor status are almost always good.

Lok...You have the wrong idea about what a "theory" is. It's not a guess that may or may not be true. A theory is just a set of statements that can be used to make predictions about results of experiments. So it doesn't make much sense to say that something is "just" a theory.

 

[Chronos]

So what you are saying is that every point is the center?

Yes, that is what Halls of Ivy is saying, and I agree.

 

[russ_watters]

The balloon analogy also makes it seem as if the universe is expanding at roughly the same rate. It isn't. Some parts go faster than others.

Incorrect: it is expanding at the same rate everywhere.

 

[seto6]

think space as a balloon. before "big bang" think if the balloon has no air then blow it up then find the center...you can't find the center. if it has cent it would contradict infinite universe

 

[IanTBlack]

Why is it expanding at the same rate everywhere?

 

[Lok]

Why is it expanding at the same rate everywhere?

Because the overall density of the whole bigbang matter is thinning, and a relativistic view of this means time is accelerating and space is expanding. It is a twofold thing that results in acelerated expansion.

 

[Fredrik]

Why is it expanding at the same rate everywhere?

Because matter is distributed approximately the same everywhere. This is actually only true on large scales, but the same can also be said about the expansion. The solar system and the galaxy isn't expanding, at least not at the same rate as the cosmological expansion.

 

[Mikeral]

What my impression of the discussion of the location of the center of the universe, would be look at it from another point of view. As a man on balloon looks around him, all he sees is a 2 dimensional plane with no possible to center to it. But when we take a look from outside the system, in a 3 dimensional point of view it is easy to find the center. Now since the human mind, like the balloon man has the concept of 2 dimensions, knows of only the concept of 3 dimensions, it would take an extra dimension to comprehend the shape of the world he lives in, the universe in our case. So in order to find the center of the universe we would have to expand our concept of 3 dimensions to include time and that the universe has a physical location but only at a specific time in existence, by that i mean, when all dimensions are at 0, like the center of the Cartesian plane, x,y and z are zero and time must be zero, therefore, the center of the universe exists at the big bang and disappears afterward.

 

[Chronos]

This is a phishing expediton, imo. Either [A] Earth is at the center of the universe, or there is no center. Choose sides. Hint - [A] is indefensible.

 

[Fredrik]

...therefore, the center of the universe exists at the big bang and disappears afterward.

The original big bang theory is just the claim that the properties of "space" changes with "time" as described by a FLRW solution. In those solutions, the phrase "at the big bang" doesn't make sense. These solutions only talk about times t>0, and at every value of the time coordinate t, the universe is homogeneous and isotropic. The big bang is the limit t→0.

There are more complicated "big bang theories" than the original, but as far as I know, none of them suggest that there was a center.

 

[Donkeylip]

First time posting here. I'm by no means an authority on the subject, and my knowledge of physics is all in layman's terms, but here is my take on the question of a center of the universe.

First I think Mikeral was using the balloon metaphor correctly. I think it is more intended too explain the limitations of how we perceive the universe, not to explain how the universe actually works.

A better metaphor is a loaf of bread. Imagine you're baking a loaf of raisin bread. As you bake the bread the dough expands. The bread is the universe, and each raisin inside it is a galaxy/galaxy cluster. Now as the dough expands and the loaf gets bigger, every raisin would see all the other raisins moving away from it. It doesn't matter where the raisin is located, the effect is universal. This is why we see the universe expanding away from us, our cosmic loaf is expanding.

Now imagine that our loaf of bread started as an infinitely small ball of dough, just like the universe. If something is infinitely small then everything is at the center. This is the core of why it will be very hard to determine the physical center of the universe.

Because of the speed of light, the farther away from Earth we look, the farther back in time we are looking. We cannot look out into the present, we can only look out into the past. If the universe started as an infinitely small point where all of the matter in our universe was technically at the center, then if we look far enough away in ANY direction we will eventually see the "center" of the universe because 13+ billion years ago everything was at the center.

Assuming the universe is finite, we will never be able to see the "edge" of it because we can only look out into the past, not the present. Thus we will never be able to determine where the current physical center is. Since matter in the universe is spread out fairly evenly, my guess is that even if we could find the current center of the universe, there probably wouldn't be anything out of the ordinary going on there.

Sorry for the long post :)

 

[Chronos]

Reminds me of one of my favorites - we are the most ancient object in the observable universe - which means we must be at the very edge. Still, everything looks pretty much the same in every direction, just younger. This is true no matter where [or when] you are in the universe. Every observer is forced to conclude they are both at the edge and the center of the universe - and neither conclusion is logical or valid.

 

[Nickelodeon]

This is a phishing expediton, imo. Either [A] Earth is at the center of the universe, or there is no center. Choose sides. Hint - [A] is indefensible.

What about [C]?

[C] could be that the red shift is caused by something other than a distance galaxy speed of recession

 

[IanTBlack]

I suppose that on a larger scale it would make sense.

 

[Greylorn]

Welcome to PF. Imagine sitting on a high mountain. Turn around in every direction - in every direction, the Earth looks roughly the same. This is a good 2d analogy for the 3d space.

Everywhere we look in space, it looks about the same. This implies rather strongly that there is no center to the universe. And expansion need not require one: replace the Earth with a giant balloon, expanding, and the analogy still holds.

I do not believe that either the mountaintop or balloon analogy is applicable to the problem. Would not the analogy of an explosion be more appropriate, since the Big Bang was an explosion?

Explosions have centers of origin. They can be located after the fact.

 

[russ_watters]

I do not believe that either the mountaintop or balloon analogy is applicable to the problem. Would not the analogy of an explosion be more appropriate, since the Big Bang was an explosion?

No. The explosion analogy is not appropriate precisely because the Big Bang was not an explosion. That's a pop-media misconception.