Is there a centre to the universe

[rollcast]

I understand that the universe is very large, possibly infinite, let's not get into that one, but does it have a definite calculated centre, ie if we start at the big bang with a very small point of massive density which then expands surely we could calculate where this point is by looking at what way the galaxies are moving away from each other and just find the centre of this movement

 

[mhenriday]

Rc1102, your analogy is tempting, but any comparison of the Big Bang with an explosion in space is misleading. Rather, what we are talking about here is an expansion of space, which, according to the observations which have hitherto been made, seems to show us nothing which would correspond to a centre. You might want to take a look at the discussion found http://math.ucr.edu/home/baez/physics/Relativity/GR/centre.html" ...

Henri

 

[rollcast]

Thanks so the universe is expanding like polyurethane foam not like a balloon.

Strange analogy but think this is right

 

[phinds]

Thanks so the universe is expanding like polyurethane foam not like a balloon.

Strange analogy but think this is right

I have a hard time with this one myself, but I don't think "expanding like polyurethane foam" is at all right because that would STILL be an expansion from a center and that has edges and the U just isn't like that. It's expanding everywhere at once and it has no edges. I'm not sure the human brain is even wired to think about this in a physical sense. I know mine isn't

 

[mjacobsca]

Even if there were a center, some inflation theories estimate the size of the universe to be orders of magnitude bigger than what we actually see (like 10^100 times bigger). We might only see a tiny filament in an intricate web-like structure encompassing all space. There's just no way to pick anyone point in our minuscule field of view and assume it's the center of everything when it might not even be the center of our branch that we can't fully see.

 

[mhenriday]

I think the point is that, so far as we - i e, astronomers, astrophysicists, experts on general relativity - know, it is not possible to calculate the trajectories of all the fleeing supra-galatic structures that we can observe in order to find a unique point in space from which all the others are receding. But after all, what we know about the universe in which we live compares to what we don't know about it, as the planet on which we live compares to the immensity which we can detect around it...

Henri

 

[phinds]

I think the point is that, so far as we - i e, astronomers, astrophysicists, experts on general relativity - know, it is not possible to calculate the trajectories of all the fleeing supra-galatic structures that we can observe in order to find a unique point in space from which all the others are receding. But after all, what we know about the universe in which we live compares to what we don't know about it, as the planet on which we live compares to the immensity which we can detect around it...

Henri

You are completely missing the point here. There IS NO POINT from which they are receding, so no reputable scientist is going to waste time looking for one.

 

[mhenriday]

No doubt, phinds, you know ever so much more about the universe than I do or, for that matter, than cosmologists like Philip Gibbs, who published the article to which I linked above. And, moreover, you seem to know a priori, just how «reputable scientists» choose to spend their time ! Despite your great knowledge, however, you express yourself with such delicacy and an utter lack of dogmatism. Admirable !...

Henri

 

[DaveC426913]

No doubt, phinds, you know ever so much more about the universe than I do

It would appear so, yes. He is correct.

or for that matter, than cosmologists like Philip Gibbs, who published the article to which I linked above.

Not sure what article you refer to but my guess is it's been deleted as not being a reputable source.

Despite your great knowledge, however, you express yourself with such delicacy and an utter lack of dogmatism. Admirable !...
Henri

I don't know why you're miffed at him for bolding the part you missed the first time around.

 

[mhenriday]

Well, my dear «science advisor», had you taken the trouble to read my first reply to rc1102's query above, you would have noticed that I did not claim that our universe has a centre from which expansion has taken place, - quite the contrary «... what we are talking about here is an expansion of space, which, according to the observations which have hitherto been made, seems to show us nothing which would correspond to a centre», and that, moreover, the http://math.ucr.edu/home/baez/physics/Relativity/GR/centre.html" to Philip Gibbs' article (which, by the way, ends as follows :

In other words, although the standard Big Bang models describe an expanding universe with no centre, and this is consistent with all observations, there is still a possibility that these models are not accurate on scales larger than we can observe. We still have no real answer to the question "Where is the centre of the universe?".)​

had, indeed, not been removed. But posting before investigating the matter at hand is ever so much more amusing, is it not ?...

Henri

 

[DaveC426913]

Well, my dear «science advisor», had you taken the trouble to read my first reply to rc1102's query above...

I did take the time to read it. And there was nothing wrong with it - which is why no one said boo. It was your next post, where you seem to miss the point. That is the one that myself and phinds are correcting.

But posting before investigating the matter at hand is ever so much more amusing, is it not ?...

I looked several times but missed it. My bad.

Moving forward, you can minimize this problem. You'll notice that most people avoid linking single words, especially here. They are small, easily missed and say nothing about what's under them. Instead, they put informative link text such as Where is the centre of the universe?.

Also, it makes no sense why you would link to that article to make your second point, since it actually refutes it.


As for your delivery, if you have a case, argue it - it should stand on its own. All this frosty sarcasm makes it hard to take you seriously.

 

[mrspeedybob]

This topic was recently discused in another thread. Rather then re-posting my thoughts on the matter I will provide a link to the other thread.

https://www.physicsforums.com/showthread.php?t=494903

 

[Odysseuz]

The question "Is there a centre to the universe" cannot be answered. The corollary to the question "Is everywhere local" might have an answer in the sub-atomic world. Does anyone know of any findings on this from the latest research?

 

[phinds]

The question "Is there a centre to the universe" cannot be answered.

Actually, it can and has been and there is no center.

 

[manojr]

Actually, it can and has been and there is no center.

And other answer is "You are at the center of your observable universe".

 

[exfret]

Phinds, you state so definitely that their isn't a center of the Universe, but how can we/you know? Is there a scientific proof on the matter? I don't understand how you can come to such a conclusion in such an absolute manner.
Also, there is a way to think of the Universe (that could be wrong, though is still an interesting idea) in which the Universe has no edge(s) or center, yet still is of finite size. First, imagine that we lived in one dimension. Now, imagine that we live on the 'surface' of a circle. It is important to remember that the Universe isn't curved from our viewpoint, because we live in one dimension, so we can't observe a curve (this is also because we live inside of the curve). Now, if you were to move continuously in one direction, you would still get back to where you started, because you would have moved completely around the circle, but you would be completely unable to deduce that this is because you are on the 'surface' a circle, because circles are two-dimensional, and you only exist in one dimension, so the idea of a circle would be completely abstract and unimaginable to you (just as we can't image living in four dimensions). Just as in this imagined universe, we could be living on the 'surface' of a four-dimensional hyper-sphere, and just as there wasn't really a center of the one-dimensional universe, there wouldn't be a center in our three-dimensional (in spatial dimensions that is) universe. Finally, just as a circle's 'surface' (its circumference) is of finite length, our real three-dimensional universe could be of finite 'volume' as well, which is how it could have no center, yet a definite/finite size.
Hmm, the word finite is in definite... I wonder if anyone else has ever noticed that before...

 

[phinds]

Phinds, you state so definitely that their isn't a center of the Universe, but how can we/you know? Is there a scientific proof on the matter? I don't understand how you can come to such a conclusion in such an absolute manner.

Google "Cosmologic Principle"

Also, there is a way to think of the Universe (that could be wrong, though is still an interesting idea) in which the Universe has no edge(s) or center, yet still is of finite size. First, imagine that we lived in one dimension. Now, imagine that we live on the 'surface' of a circle. It is important to remember that the Universe isn't curved from our viewpoint, because we live in one dimension, so we can't observe a curve (this is also because we live inside of the curve). Now, if you were to move continuously in one direction, you would still get back to where you started, because you would have moved completely around the circle, but you would be completely unable to deduce that this is because you are on the 'surface' a circle, because circles are two-dimensional, and you only exist in one dimension, so the idea of a circle would be completely abstract and unimaginable to you (just as we can't image living in four dimensions). Just as in this imagined universe, we could be living on the 'surface' of a four-dimensional hyper-sphere, and just as there wasn't really a center of the one-dimensional universe, there wouldn't be a center in our three-dimensional (in spatial dimensions that is) universe. Finally, just as a circle's 'surface' (its circumference) is of finite length, our real three-dimensional universe could be of finite 'volume' as well, which is how it could have no center, yet a definite/finite size.
Hmm, the word finite is in definite... I wonder if anyone else has ever noticed that before...

Yes, I haven't followed your exact details but a finite universe is one of the well known hypotheses and does not violate the Cosmological Principle (which DOES still imply no center and no edge). It is unknown whether the universe is finite or infinite and I have never suggested otherwise.

 

[Flatland]

Thanks so the universe is expanding like polyurethane foam not like a balloon.

Strange analogy but think this is right

You can think of the Universe as an expanding hypersphere. That's the best analogy I can come up with.

 

[Tea Jay]

I was wondering about the way we report red shifts, etc, and that we can see objects traveling away from us, etc...and was taught about the big bang as, well, a big bang...and concluded that we could then calculate where everything was going, and interpolate where they came from, and plot back to "where" this explosion was.

A brief look at this all made it look like we were at the center of this mess, and, remembering the whole Earth at center of solar system debacle, decided I was probably wrong...and looking at it wrong.

That lead me to this thread...and, EUREKA...this balloon thing makes so much more sense.

So, its like all things inflated, rather than there being an explosion, so of COURSE we all SEE things traveling relative to us that way.

I WISH in school the Big Bang was NOT presented the way it was...as the "garbage in/garbage out" collateral damage was (is) extensive.

-------------

So, NOW, my main concern is that: I can wrap my head around an infinite amount of space, as, after all, what would be past it...so, I don't think it CAN be finite. I can wrap my head around an infinite amount of time, as, well, what was before it, or after it...so, it has to be infinite as well.

What I have a LOT of trouble with, is why there is ANYTHING ELSE?

I have a feeling that there are no particles, and that everything will be some form of harmonic (I am sure I am using the wrong terms)...as matter/energy seem to be interchangeable.

So I read about quarks and so forth, and my head spins too. I think we will just keep breaking these things down and it will be like those russian dolls or something, with no end...as far as particles go.

The problems is that I can't figure out where the initial energy would come from. SOMETHING had to move or SOMETHING to make the motion that became or was energy...

...I can't get from infinite time in infinite space, to STUFF IN that space.

I don't buy the "well god made it" type explanations, as frankly, that's an even more bizarre concept...as then you'd have to ponder where HE came from, and what was he doing BEFORE that, etc...merely adding to the confusion...so it HAS TO be something else.So, just like I had no clue what I was doing about "The center" and most of this other stuff, and I am not equipped to even understand all I read about this...I'm betting that someone here can actually point me in the right direction.

:D

PS - In case I am misreading even worse...To me, time is a concept we use to describe chronology...but, to me, it can't "start" or "stop", because just before it started...is just BEFORE that start...so there was time before, etc. IE: If the big bang started xxxx gazzilion years ago, time didn't start then...as there was a time before that too.

If by "time" you guys mean the time that started at the big bang, and not my idea of time...some of what I read makes more sense. If you are saying there was no time before the bang, I don't get that at all.

 

[Xyooj]

the center of the universe is where you're at, because you're measuring from there to whatever you want.

 

[phinds]

the center of the universe is where you're at, because you're measuring from there to whatever you want.

No, the center of the OBSERVABLE universe is wherever you are. The universe as a whole does not HAVE a center.

 

[exfret]

To me, time is a concept we use to describe chronology...but, to me, it can't "start" or "stop", because just before it started...is just BEFORE that start...so there was time before, etc. IE: If the big bang started xxxx gazzilion years ago, time didn't start then...as there was a time before that too.

If by "time" you guys mean the time that started at the big bang, and not my idea of time...some of what I read makes more sense. If you are saying there was no time before the bang, I don't get that at all.

Something I like to imagine is a ray. The "start" of that ray is a point. You can't go to a place "before" that point on the ray, just like you can't go to a time before the Big Bang in the Universe, because there is no place on the ray "before" that point.

So, NOW, my main concern is that: I can wrap my head around an infinite amount of space, as, after all, what would be past it...so, I don't think it CAN be finite.

As previous posts have pointed out, the Universe doesn't have to have an edge to be finite, so it is possible for it to have a finite amount of space in it, yet have no way for it to be possible to travel "past" it. Basically, you could be stuck inside of the Universe, but have a finite amount of space to move around in. If your confused about this, than you may want to read previous people's posts in this topic on this idea.

The problems is that I can't figure out where the initial energy would come from. SOMETHING had to move or SOMETHING to make the motion that became or was energy...

A theory many scientists have believe in is the idea that the Universe has equal amounts of matter and antimatter. Basically, if you count the antimatter as having 'negative' mass, and the matter as having 'positive' mass, then they will add up to get zero, so in a way, the Universe's net amount of stuff in it is zero. An analogy that I saw on Through the Wormhole that really helped me visualize this was digging a hole. The dirt can be imagined as the matter, and the hole as the antimatter. You aren't forming more dirt, you're just making a pile of dirt and a hole. This could happen in the Universe, except the matter was "dug" out of nothing, which created antimatter. Also, if you think about it, "stuff" is just things that cause forces. Physical things can be thought of simply forces that change the world around them. Your hand has gravity, a magnet acts on the world using the electromagnetic force, both of which change the centers of some of the forces in the world (ex.- your hand pulls the center of the Earth's gravitational force towards your hand, a magnet pushes the center of another magnet's electromagnetic force (if they both have the the same poles near each other) away from it), and so on. The illusion of physical things is just a world constructed by your brain to make the world more useful for human-friendly interaction.

 

[Flashbond]

In my opinion, yes, there is a center. And, the Big Bang may not be the "point zero" because I think there is no reason for expanding "should be uniform".
Can we define the center now? I think no, because you can define something's coordinates acoording to another thing. So, it will be always a subjective, a relative center.
If we know the exact borders of the space can we define a center for this balloon? I see no reason to be negative. It won't be a constant point, but changing simultaneously.

 

[phinds]

In my opinion, yes, there is a center.

Personal speculation, ESPECIALLY unsupportable speculation, is not allowed on this forum.

 

[Flashbond]

Personal speculation, ESPECIALLY unsupportable speculation, is not allowed on this forum.

Ok, don't take me wrong but there is nothing can be caculatable or absolute about this. Every assumption about this topic, will be personal. The space expands faster than light and it is 72 billion light-years wide and I am sure nobody has a clear data where it begins and ends and again personally, never will. So I am sure every idea or "theory" will highly be "speculative" about this subject. If you want to ban me then, you'll be my guest but this is how I am thinking and I can't help it.
What are you expecting for? Should I script down an algorithm to build a chaotic space-time model to prove the expansion can be nonuniform? Or should I use cool theory names which are alredy known by %90 here?

 

[phinds]

Every assumption about this topic, will be personal.

No, it will not. The fact that the universe does not have a center is NOT an assumption, it is part of the standard Cosmological Model, which you might find interesting to look into.

 

[sodaboy7]

A line is 1-dimensional object. You can imagine a line as part of huge 2-dimensional circle of infinite radius. Likewise a 2-D surface (an infinite plane) is a part of surface of a 3-D sphere of infinite radius. Similarly, an 3-D space is a part of surface of 4-D sphere (only for visualization purpose). Assume that Earth is a perfect sphere. If you ask ,where on the surface is the center of Earth ? The answer is every point on surface acts as a center or there is no center at all. The same question when asked to 3-D surface of a 4-D sphere gives the same answer - EVERY POINT IS A CENTER OR THERE IS NO CENTER AT ALL.

 

[exfret]

If we know the exact borders of the space can we define a center for this balloon?

You are using the balloon analogy wrongly. It does not imply edges or borders to the Universe. In fact, you are imagining a universe that is almost the complete opposite of the one in the balloon analogy. The surface of the balloon is the Universe imagined. In the balloon analogy, there is no center and there are no edges. (This does not mean, though, that the universe of the balloon is infinite). The Universe you are proposing is probably one of the least accepted ones in the scientific community. If the Universe has an edge, then that leads to the question of what is past those edges, and that creates a problem.

Ok, don't take me wrong but there is nothing can be caculatable or absolute about this. Every assumption about this topic, will be personal.

"Nothing" is quite an absolute statement that I believe you are wrong about. How do you know that there is absolutely no way whatsoever to calculate even an approximation of the center of the Universe and if it exists. Also, you don't have to bring personal assumptions into science just because you don't know enough about something yet, though you can make hypotheses and predictions. This is what I believe you were trying to do, albeit without much ground to support your belief. My point is we don't have to get our knowledge of a topic completely out of personal belief just because we don't know enough about something yet. Also, not being able to calculate an absolute center to the Universe does not make it so that nothing is calculable. Scientists can calculate chances and use the mathematics of probabilities and statistics to sort things out. In fact, scientists do this all the time, and not just in quantum mechanics. So, even though we can't yet know doesn't mean we can't yet come up with a likely theory.

If you want to ban me then, you'll be my guest but this is how I am thinking and I can't help it. What are you expecting for?

I do believe that your speculation/prediction/personal opinion was okay to have, but you were purely speculating. You should probably think about why you think a certain way and put that in before you post next time. If there is no reason why you think a certain way, then you should probably consider thinking from another viewpoint that is more likely. This may be hard, but one of the demands of being a scientist is to be open-minded, and science is what these threads are all about. Also, you probably shouldn't be talking back to a member of the physics forum community, especially an honored one with over 4,000 posts (and, in my personal opinion, whose posts are very accurate and well-written, albeit forceful). Phinds was only suggesting that you leave in some evidence. If you have a problem with the way someone words something, then you should probably message them, not post onto the topic saying that you want to get banned from the physics forums community, because that is, quite literally, asking to get banned from these great forums. That is probably not something you want.

Should I script down an algorithm to build a chaotic space-time model to prove the expansion can be nonuniform? Or should I use cool theory names which are alredy known by %90 here?

Actually, both of those would be a very nice addition to this topic. I would especially look forward to the chaotic space-time model, but I realize that you are being sarcastic, and sadly won't offer this to the readers of this thread. You don't have to write a scientific paper. You can, though, offer why you think the way you do. You shouldn't be mad at the fact that you should evaluate upon your ideas. If you don't like to think about that sort of stuff, then this forum probably isn't right for you. I hope that you do actually enjoy to think, because then your ideas would be a valuable contribution to this discussion.

 

[Chronos]

Logic is not a substitute for science. You are ignoring the contribution of many dedicated researchers. If you have an issue with that, you need to show the math.

 

[Delong]

I'm sorry but I remain unconvinced. Any volume if space will have have a geometric center this is just basic geometry. Even if space itself is expanding rather than just matter/energy that space has a center throughout the expansion. It's just geometry. The only way it wouldn't have a center is if space were infinite or it looped back on itself. I don't think either of these scenarios are supported by evidence but I could be wrong.

 

[Ger]

Another approach: the impossibility to find a centre of mass point in (hyper)space. To triangulate such point one needs at least a point at 'the other side' of hyperspace. Getting there by traveling over the surface isn't do-able, as you have no way of knowing where that other side may be. Even if we have contact with other civilisation through a hyperspace communication channel (neutrino's?) beyond our horizon both do not know where we are on the surface. Take at least 6 other communication channels (at least more than the 4 dimension we know of + 1 for the hyperspace + possible 1 communication dimension). Hyperspace we can construct, imagine. But never enter. Communication dimensions we can construct but its medium isn't hyperspace.
Leaves us with one lacking dimension, actually 2 dimensions so a solution would always describe a infinite plane where the centre might be. But your centre is there to pinpoint, infinite number of possibilities.

It's all relativity said the farmer chasing his wife round the table, you think you are chasing me, I think I am chasing you.

 

[phinds]

I'm sorry but I remain unconvinced. Any volume if space will have have a geometric center this is just basic geometry. Even if space itself is expanding rather than just matter/energy that space has a center throughout the expansion. It's just geometry. The only way it wouldn't have a center is if space were infinite or it looped back on itself. I don't think either of these scenarios are supported by evidence but I could be wrong.

The universe doesn't care whether you are convinced or not. You might think about learning some basic topology before making unsupportable statements such as the one in red.

 

[Delong]

The universe doesn't care whether you are convinced or not. You might think about learning some basic topology before making unsupportable statements such as the one in red.

Psh and I thought I would not impolite jerks in science. The statement I made makes total sense unless you can provide a counter example. The burden of proof is on you as far as I see. As long as the universe has some kind of finite shape it has a center, I repeat that is just basic geometry.

 

[WannabeNewton]

Give your mathematically rigorous definition of the center of a 3-manifold and we can move on from there.

 

[phinds]

As long as the universe has some kind of finite shape it has a center, I repeat that is just basic geometry.

And I say, again, you might think about learning some basic topology before making unsupportable statements.

And by the way, I should have added that the universe doesn't care what I think either. I did not mean anything personal by that I was just pointing out that you are expressing an opinion (an incorrect one as it happens) where you think you are stating a fact.