B What is the center of the universe?

[KylieVegas]

I read in a book that there is no center of the universe because for example, you put dots around a balloon, and when you put air into the ballon, the dots will separate from each other, and each dot will see themselves as the center of the balloon, depending on the dots' perspective. That only applies if our universe is spherical, like a balloon. But the accepted shape of our universe is flat, in that case, what is the center of our universe? Please tell me if i miss out something, and i am open to any other theories/facts. Thank you and have a nice day!:)

 

[Drakkith]

There is no center of the universe that we know of.

 

[jaormsby]

There is no definitive center of the Universe. The only center we can define is the center of the observable Universe but the Universe itself extends far beyond that. Exactly how far can't be determined.

 

[Chronos]

The 'center' of the universe is an observer dependent illusion, just like the 'edge' of the universe. Wherever you may be in the universe it appears you are both at its 'center' and at its most ancient point. See any logical disconnects with that?

 

[phinds]

I read in a book that there is no center of the universe because for example, you put dots around a balloon, and when you put air into the ballon, the dots will separate from each other, and each dot will see themselves as the center of the balloon, depending on the dots' perspective. That only applies if our universe is spherical, like a balloon. But the accepted shape of our universe is flat, in that case, what is the center of our universe? Please tell me if i miss out something, and i am open to any other theories/facts. Thank you and have a nice day!:)

You would do well to read the link in my signature

 

[tfr000]

The balloon thing is meant to be a 3-d model of 4-d space. In other words, the inhabitants of the balloon universe are trapped in the thin skin of the balloon. If they go in any direction, they end up back where they started, hence, no center that they can detect. Extrapolate to the real universe...

 

[phinds]

The balloon thing is meant to be a 3-d model of 4-d space.

No, it is essentially a 2D model of 3D space. We don't live in 4D space. I suggest that you too read the link in my signature.

 

[SteamKing]

I read in a book that there is no center of the universe because for example, you put dots around a balloon, and when you put air into the ballon, the dots will separate from each other, and each dot will see themselves as the center of the balloon, depending on the dots' perspective. That only applies if our universe is spherical, like a balloon. But the accepted shape of our universe is flat, in that case, what is the center of our universe? Please tell me if i miss out something, and i am open to any other theories/facts. Thank you and have a nice day!:)

Everybody knows it's Boston, Massachusetts. After all, Boston is nicknamed "The Hub", as in "the Hub of the Universe".

https://en.wikipedia.org/wiki/Boston_nicknames

 

[newjerseyrunner]

How would you define the center? If you are on a line, the center would be defined as the point where you have the exact same amount of distance in front of you and behind you. If both ends go off to infinity, no matter at what point in the line you are, you always have infinity in front and behind you, therefore you can not define a location where you have the same distance in front and behind you. infinity does not equal itself.

 

[KylieVegas]

Thanks for the reply guys! I did some research and i understand it now :)

 

[KylieVegas]

Anybody who ask this question should be instant perma-banned from this forum. Damn these people are annoying!

You don't have to be rude, i asked because i didn't understand :)

 

[phinds]

You don't have to be rude, i asked because i didn't understand :)

I agree. Just so you know, if you object to a post, you can report it using the report button that exists in each post. The moderators have a low tolerance for rude behavior, as I know very well 'cause I get called on the carpet every now and then when I forget to bite my tongue

EDIT: sometimes people come here and ask very basic questions, clearly without having made the slightest attempt to figure things out for themselves. This can be annoying, but you clearly did not do that (and even if you had, the moderators still ban rudeness).

 

[Chronos]

Phinds, don't be put off by naive questions - we all have suffered that disorder. Cosmology is complicated. I like them, they are the easiest to answer with any sense of confidence.

 

[phinds]

Phinds, don't be put off by naive questions - we all have suffered that disorder. Cosmology is complicated. I like them, they are the easiest to answer with any sense of confidence.

Oh, I have NO problem with naive questions. I was full of them when I first decided a few years back to start learning a bit about cosmology and quantum mechanics. What I object to is people who make no effort on their own. The OP had clearly made an attempt to figure it out and was understandably puzzled, which is the perfect time to come here to PF for help.

 

[Joe Ciancimino]

Not exactly accepted theory, but I tend to think of the center of the universe as the past and the universe expands into the future. Works well in a 4D model, even better in a 5D model of Hugh Everett's many worlds interpretation so long as the universe is not flat.

 

[Drakkith]

Not exactly accepted theory, but I tend to think of the center of the universe as the past and the universe expands into the future. Works well in a 4D model, even better in a 5D model of Hugh Everett's many worlds interpretation so long as the universe is not flat.

Unfortunately this is likely to cause even more confusion than the standard analogies.

 

[DHF]

I had similar questions on the Center of the universe a while back. I found it difficult to grasp the concept of no center but then someone here (I am sorry I can't remember who posted) asked "where is the center of the surface of the Earth?" That helped me get my head around the idea that there is no center to the universe.

 

[nuwanda]

Thanks for the reply guys! I did some research and i understand it now :)

OK, perhaps you could share your understanding since your beginner perspective would help someone like me. Others here may join in, of course.

I have this image of a starting point expanding outwards in the form of the ballooning surface. At that moment a center ceases to exist and becomes a surface with the matter of the original center on it, each bit of that matter expanding away from each other as the surface of the balloon expands.

If that's not a reasonable image, albeit simplistic, by what description can the universe be said to have had a starting point from which matter originated?

Further, does this mean that, in the balloon model, that the balloon is empty and all that exists is on the surface?

Further again, I may be having a problem with this idea that a void, an emptiness, now exists within this balloon upon which the surface rests, and a void into which the surface is expanding. I guess this goes to the perhaps mistaken idea that something existed outside the origin into which things are expanding.

By the way, if there's a beginner's forum I should use, please let me know.

 

[Drakkith]

I have this image of a starting point expanding outwards in the form of the balloon surface. At that moment a center ceases to exist and becomes a surface with the matter of the original center on it, each bit of that matter expanding away from each other as the surface of the balloon expands.

If that's not a reasonable image, by what description can the universe be said to have had a starting point from which matter came?

It can't be said to have a starting point at all. That's the entire point (pun not intended).

 

[Bandersnatch]

@nuwanda it's easier to start from the present time and go backwards, rather than the other way around.
Working some more with the analogy at hand, if you have this balloon's surface, and start deflating the balloon, then the surface will become more and more compact, and points on it closer and closer together, but no matter how small you'll make the balloon, it'll never stop having a surface and will not turn into a point.
Even an infinitely small balloon is still a balloon.

 

[nuwanda]

Certainly we can say that a thing compressed will always be a smaller version of itself. But at a certain point, conceptually, is that the singularity from which the universe originated?

Conceptually it's easy to imagine infinitely small versions of a thing. Just as it's easy to consider an infinitely long series of numbers. But that's not what I'm asking. Going to the discussion point of a center I can see that a balloon surface expanding means that the matter on the surface of the balloon has no center, although it certainly seems to have an origin within the balloon from which it expanded.

Is it a matter of confusing the terms origin (singularity) and center? Because I can certainly see that our current position on the surface of the balloon in relation to other locations on that surface doesn't need any reference to an original origin point.

@nuwanda it's easier to start from the present time and go backwards, rather than the other way around.
Working some more with the analogy at hand, if you have this balloon's surface, and start deflating the balloon, then the surface will become more and more compact, and points on it closer and closer together, but no matter how small you'll make the balloon, it'll never stop having a surface and will not turn into a point.
Even an infinitely small balloon is still a balloon.

 

[Bandersnatch]

The balloon analogy requires you to discard the concept of anything beyond its 2-dimensional surface. The 3D 'centre' of the balloon is not supposed to represent anything about our universe.

You're right, the singularity shouldn't be confused with the centre. The singularity is what you get when you do try and get the 'balloon' to an infinitely small size. Much like with a function of the form $1/x$, if you try to get it to zero, it stops being defined. I.e.: the function has a singularity at x=0, same as the BB theory ends up with a singularity at scale factor a=0 (scale factor is the fraction of current distances, so at a=0 everything is on top of everything).

The singularity is commonly taken to mean that the theory is unfit to describe a regime where it appears, not that it represents anything physical.

 

[nuwanda]

OK, I may need to reset here.

In what way is our universe different than a firework that has exploded, we the sparks, and the original firework no longer in existence?

We have a singularity, conceptually, the origin of our universe. Is the term expansion invalid? That is, what did matter and energy expand into? And if expansion is valid as a cosmological term, then the expansion must have occurred away from something and into something else.

I think I'm reasonably good at abstractions being a programmer by trade. But analogies help when concepts are too abstract. Are there more helpful analogies than the expanding balloon?

The balloon analogy requires you to discard the concept of anything beyond its 2-dimensional surface. The 3D 'centre' of the balloon is not supposed to represent anything about our universe.

You're right, the singularity shouldn't be confused with the centre. The singularity is what you get when you do try and get the 'balloon' to an infinitely small size. Much like with a function of the form $1/x$, if you try to get it to zero, it stops being defined. I.e.: the function has a singularity at x=0, same as the BB theory ends up with a singularity at scale factor a=0 (scale factor is the fraction of current distances, so at a=0 everything is on top of everything).

The singularity is commonly taken to mean that the theory is unfit to describe a regime where it appears, not that it represents anything physical.

 

[Bandersnatch]

You should not think of the BB as an explosion into a pre-exising empty space.

Perhaps these articles will help you wrap your head around better than I can:
http://www.phinds.com/balloonanalogy/
http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf

These both talk about the balloon analogy. There's also the raisin-bread analogy, but maybe give those two a read first.

 

[nuwanda]

OK. My idea of expanding into something is not right. I get that. I was wrong to suggest something out there existed.

But the idea of expanding away from an origin surely must be valid. I think that's what most amateurs conceive as a center.

You should not think of the BB as an explosion into a pre-exising empty space.

Perhaps these articles will help you wrap your head around better than I can:
http://www.phinds.com/balloonanalogy/
http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf

These both talk about the balloon analogy. There's also the raisin-bread analogy, but maybe give those two a read first.

 

[Bandersnatch]

The second link opens into a blank screen.

scroll down, it's just a page or two

 

[phinds]

Besides, the first link should be enough.

 

[DHF]

your 100% unbiased opinion from Phinds :D

 

[phinds]

your 100% unbiased opinion from Phinds :D

I am a paragon of objectivity

 

[Drakkith]

But the idea of expanding away from an origin surely must be valid. I think that's what most amateurs conceive as a center.

Nope. There is no origin. The nature of things is such that every observer sees themselves as stationary with the rest of the universe expanding away from them. And every observer is correct.

 

[Wanted]

It depends entirely upon your notion of the meaning of the word center... and some understanding of what the universe potentially is.

If you're defining center as a point in which everything moves away from in any direction then there is no center. In this case everywhere would fit the definition Unless you're on the edge of moving into never explored empty area of the universe. This would mean you appear to be at the center since no matter where you are everything moves away from you in all directions... unless you were observing from the 'expanding edge'.

If you're defining center as the origin from which everything started moving from then it'd be in the origin of where the singularities expansion would be assuming it is equal in all directions since it wasn't an explosion in an empty space but rather everywhere at all once exploding. But this is more of a geometric center like below

If you're defining the center as the midway point between all 'expanding edges' then it would be indeterminable by us (our and probably any possible technology) by geometrically on a XYZ 3 dimensional plane (Left Edge + Right Edge)/ 2, (Front Edge + Back Edge)/ 2, (Top Edge + Bottom Edge)/ 2... or some other ambiguous means of taking indeterminable XYZ 3 dimensional plane coordinates and averaging them... one such other way would be to take the x,y,z coordinate of every proton (or whatever have you) in the universe and averaging it together.

You know theory shouldn't be limited just because communication, language, and definitions are. I'm sure this is a lot more helpful to understand than 'there is no center'.

When the real question is what does center even mean, and is it useful to know... probably not.

 

[Drakkith]

If you're defining center as a point in which everything moves away from in any direction then there is no center. In this case everywhere would fit the definition Unless you're on the edge of moving into never explored empty area of the universe. This would mean you appear to be at the center since no matter where you are everything moves away from you in all directions... unless you were observing from the 'expanding edge'.

There is no edge. No matter where you are in the universe, everything will appear to be expanding outwards, moving away from you at an increasing velocity as the distance between you and the object.

If you're defining center as the origin from which everything started moving from then it'd be in the origin of where the singularities expansion would be assuming it is equal in all directions since it wasn't an explosion in an empty space but rather everywhere at all once exploding. But this is more of a geometric center like below

Again, there is no point of origin.

If you're defining the center as the midway point between all 'expanding edges' then it would be indeterminable by us (our and probably any possible technology) by geometrically on a XYZ 3 dimensional plane (Left Edge + Right Edge)/ 2, (Front Edge + Back Edge)/ 2, (Top Edge + Bottom Edge)/ 2... or some other ambiguous means of taking indeterminable XYZ 3 dimensional plane coordinates and averaging them... one such other way would be to take the x,y,z coordinate of every proton (or whatever have you) in the universe and averaging it together.

Since there is no expanding edge, there is no absolute center.

Some links:
http://www.talkorigins.org/faqs/astronomy/bigbang.html#misconceptions
http://www.astro.ucla.edu/~wright/cosmolog.htm (see the FAQ)

 

[Wanted]

There is no edge. No matter where you are in the universe, everything will appear to be expanding outwards, moving away from you at an increasing velocity as the distance between you and the object.

You can't have things moving away from you in a direction in which things are not occupied. If you happened to be there. Sure you'd have things moving away from you in one direction... but not every. Edge simply means you are ahead of anything else in the direction you are traveling and will cease to see anything new in the direction you're traveling because you have already passed everything or were already ahead to begin with.

Again, there is no point of origin.

I don't describe the origin as a 'point' .There is no point of origin since it encompasses everything, however there is a geometric average from the expanding edges assuming expansion is equal in all directions.

Since there is no expanding edge, there is no absolute center.

There has to be an expanding edge because the universe is constantly expanding in unoccupied space. There is no absolute center because center has many definitions and fulfilling these definitions requires indeterminable data or doesn't have a center.

Some links:
http://www.talkorigins.org/faqs/astronomy/bigbang.html#misconceptions
http://www.astro.ucla.edu/~wright/cosmolog.htm (see the FAQ)

The first link explains why the TBB is not a point, which is not a claim I am making.
The second links explains a list of things only a few of which I can find directly relevant (would help if you were specific). The relevant section I found was http://www.astro.ucla.edu/~wright/nocenter.html which states there is no center based on the predication that center is defined as a point in which everything moves away from which I agree it does not have.

 

[phinds]

You can't have things moving away from you in a direction in which things are not occupied. If you happened to be there. Sure you'd have things moving away from you in one direction... but not every. Edge simply means you are ahead of anything else in the direction you are traveling and will cease to see anything new in the direction you're traveling because you have already passed everything or were already ahead to begin with.

I don't describe the origin as a 'point' .There is no point of origin since it encompasses everything, however there is a geometric average from the expanding edges assuming expansion is equal in all directions.

There has to be an expanding edge because the universe is constantly expanding in unoccupied space. There is no absolute center because center has many definitions and fulfilling these definitions requires indeterminable data or doesn't have a center.

The first link explains why the TBB is not a point, which is not a claim I am making.
The second links explains a list of things only a few of which I can find directly relevant (would help if you were specific). The relevant section I found was http://www.astro.ucla.edu/~wright/nocenter.html which states there is no center based on the predication that center is defined as a point in which everything moves away from which I agree it does not have.

This stuff about the edge is nonsense. There is no edge. You need to re-read Drakkith's post #32 and study cosmology until you understand that what he said is correct.

 

[Wanted]

This stuff about the edge is nonsense. There is no edge. You need to re-read Drakkith's post #32 and study cosmology until you understand that what he said is correct.

There is potential for falsity in any argument, however I cannot locate any in post #32.

It's easy, and entirely pointless, to just say something is nonsense with absolutely no counter argument.

Edge as in a boundary is not what I mean at all... there is obviously no physical edge wall in unlimited open void space.

Universe as in empty space is infinite but the matter, energy, and other non-void components that occupies it is not.

If your model for the universe is a spherical one then if you traveled in one direction long enough you would end up where you started similar to as if you sailed around the world, but this is an assumption... it's much more rational that the void of the universe expands endlessly in all directions and traveling in a single direction could never bring you back to where your voyage began.

Edge refers to expansion of nonvoid into the void.

 

[Drakkith]

You can't have things moving away from you in a direction in which things are not occupied. If you happened to be there. Sure you'd have things moving away from you in one direction... but not every. Edge simply means you are ahead of anything else in the direction you are traveling and will cease to see anything new in the direction you're traveling because you have already passed everything or were already ahead to begin with.

Again, there is no edge. You can travel as far as you like but you will never find an edge. You will only keep finding matter in all directions.

There has to be an expanding edge because the universe is constantly expanding in unoccupied space. There is no absolute center because center has many definitions and fulfilling these definitions requires indeterminable data or doesn't have a center.

The universe is not expanding into unoccupied space. The distance between all unbound objects is simply growing larger over time.

The first link explains why the TBB is not a point, which is not a claim I am making.
The second links explains a list of things only a few of which I can find directly relevant (would help if you were specific). The relevant section I found was http://www.astro.ucla.edu/~wright/nocenter.html which states there is no center based on the predication that center is defined as a point in which everything moves away from which I agree it does not have.

What you claimed, and what you claim that you've claimed, do not match. Your explanations require that the universe expanded outwards from a single point, whether you realize they do or not.

 

[Wanted]

Again, there is no edge. You can travel as far as you like but you will never find an edge. You will only keep finding matter in all directions.

In order for this to be true the amount of matter in the universe would have to be infinite. Something for which there is no verifiable/observable evidence to suggest.

The observable universe is 46.6 billion light years across with a finite amount of matter.

The universe is not expanding into unoccupied space. The distance between all unbound objects is simply growing larger over time.

Based on the previous predication for which there is no verifiable/observable evidence.

What you claimed, and what you claim that you've claimed, do not match. Your explanations require that the universe expanded outwards from a single point, whether you realize they do or not.

Only if based on the predication of universe with infinite mass which for which there is no verifiable/observable evidence.

Imho, and many others, finite matter is more rational than infinite matter. In which case the previous claims would not be invalidated by the assumptions in the context of infinite matter.

 

[Drakkith]

In order for this to be true the amount of matter in the universe would have to be infinite. Something for which there is no verifiable/observable evidence to suggest.

That is another incorrect statement. It is entirely possible for the universe to be unbounded yet finite, which would still mean that there is no edge and no center despite there being a finite amount of matter. In any case, I know of no accepted cosmological models where the universe is infinite and unbounded yet doesn't have an infinite amount of matter.

Imho, and many others, finite matter is more rational than infinite matter. In which case the previous claims would not be invalidated by the assumptions in the context of infinite matter.

You opinion on the rationality of infinite vs finite is irrelevant. The models that are most accepted by cosmologists are those where the matter in the universe is homogeneous at the largest scale. Models in which matter is not homogeneous (as required by any model with an 'edge') are, generally, not looked upon favorably, as they lack both evidence and rigorous theories to support them.

 

[Drakkith]

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