Center of the universe.

[Enforcer Productions]

I was thinking about it, and if the galaxies orbit the universe, then what do they orbit around? Has anyone found an answer?

 

[Alexa]

A huge black hole ?

 

[tinkerdan]

Whatever there might be at the center of a massive explosion.

Perhaps nothing more than a Pile of Bones.

 

[Venusian Broon]

If you believe the big bang theory then the mathematical centre of the universe (where the big bang first appeared) is currently non-existent.

An analogy to try and explain what the big bang theory says:

Think of the universe like a balloon with galaxies 'painted' on it, and imagine then a 2 dimensional creature that can only live on the surface of the balloon in one of these galaxies. By blowing the balloon up this 'universe' is expanding and the galaxies are getting further and further away. The centre, where we assume our balloon started out completely deflated (let's assume for the moment it's some sort of perfect mathematical balloon!) however is not part of the balloon therefore our 2 dimensional creature, being stuck on the surface can never reach this 'unphysical' spot as it no longer exists in the current universe. And note, it does not exist for our galaxies either.

In our case we are three dimensional creatures and our universe is like a three-dimensional 'balloon'. We too are seeing that most of the galaxies are moving away from us as they are being driven apart by an expansion. The expansion, analogous to 'blowing into the balloon' in the analogy was driven by the energy of the initial big bang and also, we believe, by something called 'dark energy' which has been measured accelerating this expansion. Which is a head scratcher and puzzling to all.

So to finally answer the OP question, galaxies don't orbit the 'centre'- they are all just taking a ride on the universes big expansion. However as the universe has patches of dense and less-dense matter, individual galaxies will happily orbit bigger centre of masses in the neighbourhood if 'it makes sense gravitationally'!

 

[tinkerdan]

I can't help but think if we are going to draw analogy from two dimensions we'd have a better chance using a Klein bottle.
Regardless though; however the big bang came about and from whatever dimension it might have erupted into ours we still have three and possibly four dimensions in this universe, so I can't help but guess that there might be some center to that if we could ever agree on the shape and scope of the universe we might even find it; however it may just remain something theoretical to discuss after a few drinks on an otherwise boring night.

 

[Venusian Broon]

I can't help but think if we are going to draw analogy from two dimensions we'd have a better chance using a Klein bottle.
Regardless though; however the big bang came about and from whatever dimension it might have erupted into ours we still have three and possibly four dimensions in this universe, so I can't help but guess that there might be some center to that if we could ever agree on the shape and scope of the universe we might even find it; however it may just remain something theoretical to discuss after a few drinks on an otherwise boring night.

Again with the proviso that we assume that the Big Bang is what occurred...

Yes there is a 'centre'. It's just not physical anymore. It does not exist and we can never visit it. But we can imagine it mathematically. Remember the Big Bang did not 'explode' in a pre-existing three-dimensional space, that is a common misunderstanding of General Relativity and the Big Bang. The theory states that there was no four-dimensional space-time before the big bang (as far as we know). The universe expanding from a point of infinite density created an expanding shell of four-dimensional space-time (centred around the completely inaccessible starting point)

However that means if you took the fourth dimension, time, then went down the 'time-axis' to t=0 you'd find your centre actually physically realised. You'd just need a time machine capable of doing that (although then, you'd likely be mashed into an extremely tiny space by the contraction of the universe, so I don't rate your chances of survival...)

Steady state theory would, I assume, have some sort of actual and real 'centre' sitting in space somewhere. However, as we have spent ~13.4 Billion years expanding away from it at pretty high speeds, again I think your chances of actually getting there, if this theory were correct, would essentially be zero.

 

[BAYLOR]

What is at the center? Its a excellent question and topic.

But how we find the exact center of the universe ?

 

[Mirannan]

Two answers here, and I'm not sure how correct one of them is:

One is that the entire universe is expanding uniformly in all directions with no unique centre; at the Beginning there was only a singular point (or as close to it as our mathematics can get) which comprised the entire universe and it started expanding - perhaps in a dimension outside 4D spacetime or at any rate outside 3D space. So the centre of the universe is in the same place as it always was - everywhere. Pick the end of your nose, or the centre of the Andromeda galaxy - all of them are the centre and/or none of them.

The second one I'm not so sure about. To my possibly naive mind, it seems that if the universe is expanding then the expansion has to be in a dimension not in the universe - much as in the often used balloon analogy. The centre of the expansion in the latter is outside the surface of the balloon; in the centre of it, in fact. So if there is a centre to the universe (assuming it has positive curvature) then the centre of the universe is actually outside the universe, in a 5th-dimension direction.

Not an exact analogy, I know.

 

[J Riff]

Scientists have discovered that everything keeps getting bigger and bigger, until this universe would fit inside a single molecule, which is part of an ant's leg, in a universe where things get bigger and bigger until even God has trouble keeping it clean.

 

[Foxbat]

So the centre of the universe is in the same place as it always was - everywhere. Pick the end of your nose, or the centre of the Andromeda galaxy - all of them are the centre and/or none of them.

So Hawkwind were right when they sung: I am the centre of the universe...
Who needs science when you've got Cosmic Rock

 

[Vladd67]

Well I’ve always known I am the centre of the universe.

 

[Cathbad]

I'm a pustule on an anterior leg of the universe.

 

[night_wrtr]

Someone needs to get PBS Space Time to do an episode about this.

 

[hitmouse]

Two answers here, and I'm not sure how correct one of them is:

One is that the entire universe is expanding uniformly in all directions with no unique centre; at the Beginning there was only a singular point (or as close to it as our mathematics can get) which comprised the entire universe and it started expanding - perhaps in a dimension outside 4D spacetime or at any rate outside 3D space. So the centre of the universe is in the same place as it always was - everywhere. Pick the end of your nose, or the centre of the Andromeda galaxy - all of them are the centre and/or none of them.

The second one I'm not so sure about. To my possibly naive mind, it seems that if the universe is expanding then the expansion has to be in a dimension not in the universe - much as in the often used balloon analogy. The centre of the expansion in the latter is outside the surface of the balloon; in the centre of it, in fact. So if there is a centre to the universe (assuming it has positive curvature) then the centre of the universe is actually outside the universe, in a 5th-dimension direction.

Not an exact analogy, I know.

There is no reason why spacetime should not be expanding in the commonly observed 4 dimensions. Indeed, experimental observation such as the Hubble red-shift suggest this is the case.

More esoteric dimensions may have been proportionately more significant immediately after the big bang.

 

[LordOfWizards]

I've read all of the modern scientific theory and wiki articles on this, and I'm not convinced by the statement that is most often quoted: The Cosmological Principle: " is the notion that the spatial distribution of matter in the universe is homogeneous and isotropic when viewed on a large enough scale, since the forces are expected to act uniformly throughout the universe, and should, therefore, produce no observable irregularities in the large-scale structuring over the course of evolution of the matter field that was initially laid down by the Big Bang...." Cosmological principle - Wikipedia

The reason I'm not convinced is two fold: 1) the W-MAP Image of the universe constructed from the echo of cosmic background radiation (here) looks like it should have a center.
2) The question I ask in the paper I wrote about this topic: "If the universe is expanding, then where is it expanding from?"

I interpret the Cosmological Principle (as stated above) to mean that wherever you are in the universe, you are in the center. The only way for that to be possible would be that the universe is indeed infinite, and we can only see 14 billion light years out no matter where we observe from in the universe.