In currently understood physics, does the universe have a centre?

[DaveC426913]

A simple question. No tricks here. Yes or no.

 

[marcus]

Dave I hope everybody realizes that in currently understood cosmology the observable portion is distinguished from the whole universe. The "observable universe" is one thing, and the "universe" is something else. You learn that in your first General Astro course in college.

The observable obviously has us and the Milkyway galaxy as center because it extends out in all directions to the farthest matter that we have so far gotten light from. Since it doesn't make sense to ask---obviously it is a big ball with us at the center---I assume your question is about the universe proper, not just what we so far have gotten signals from.

How you picture that depends on which version of the standard cosmo model you use, but in no case does it have a center.

 

[Scrufuss]

I don't think that a universe that is infinite could have a center. The observable universe is to vast and randomly scattered to have a center.

Just sayin'

 

[Chaos' lil bro Order]

I would reckon an infinite # of centers given the current models.

Question: As marcus points out, the Universe as we know it is comprised of the observable and hyper universe. Personally I think this is a stupid idea to envisage a hyper universe beyond what is observable, but I can understand the need to create such a hyper universe considering that the observable horizon decreases in size as, distant quasars with co-moving velocties with respect to Earth exceeding C, wink out of the observable universe every year. You may be tempted to say they enter the hyper universe, but I think its more correct to say the observable universe merely shrinks. What evidence is there for a hyper universe?

Furthermore, have astronomers really seen the fringes of the universe in all vectored directions outwards from Earth? Sure we see the Abell quasars nearly 13billion L.Y. away and every year we find a new 'object' closer and closer to the theoretical observable time horizon of 13.7B L.Y., but do we have enough data to say with at least some degree of certainty that this horizon is uniform in time distance?

I cannot accept any mathematical theory that tackles physics problems without a geometrical model written by the author that is supported by their math. Geometry is what is valuable. Physics is physical.

 

[matt.o]

What the heck is the Abell quasar?

The furthest we've seen is the CMB.

 

[cristo]

I'm not really sure the point of this poll. As has been discussed here many times, the universe does not have a centre.

 

[DaveC426913]

I'm not really sure the point of this poll. As has been discussed here many times, the universe does not have a centre.

To show poor https://www.physicsforums.com/showpost.php?p=2302074&postcount=153" that it's not merely my opinion.

 

[nicksauce]

Well played.

 

[humanino]

I'm not really sure the point of this poll. As has been discussed here many times, the universe does not have a centre.

Can I use this thread to request about privileged direction ? Is there an axis of evil in WMAP data on the CMB ? Will Planck's polarization data help resolve this question ?

 

[Phrak]

I would reckon an infinite # of centers given the current models.

Question: As marcus points out, the Universe as we know it is comprised of the observable and hyper universe. Personally I think this is a stupid idea to envisage a hyper universe beyond what is observable, ...

If you re-read marcus, rejecting a greater universe--beyond what is observable--requires that you accept the solar system as uniquely centered in the universe.

 

[apeiron]

If you re-read marcus, rejecting a greater universe--beyond what is observable--requires that you accept the solar system as uniquely centered in the universe.

I think the light cone view moves the discussion nicely from a 3D perspective to a 4D one. So a centre would have to be a locale in both space and time.

Then we would say that every point in the universe is its own centre. So the centre is both everywhere and nowhere. And this is a positive fact about the universe which gives it that essential quality of locality (and makes troublesome the aspects which are nonlocal or un-centred in this sense).

 

[Chaos' lil bro Order]

Dave I hope everybody realizes that in currently understood cosmology the observable portion is distinguished from the whole universe. The "observable universe" is one thing, and the "universe" is something else. You learn that in your first General Astro course in college.

The observable obviously has us and the Milkyway galaxy as center because it extends out in all directions to the farthest matter that we have so far gotten light from. Since it doesn't make sense to ask---obviously it is a big ball with us at the center---I assume your question is about the universe proper, not just what we so far have gotten signals from.

How you picture that depends on which version of the standard cosmo model you use, but in no case does it have a center.

Ok, but if we stand on a planet in Andromeda the same view applies. Wherever you are standing, you are at the center of the observable universe. I think apieron gives the truest description and the one myself and the general public hate the most :) There is no center and we are not conclusively located in a spherical universe. We can't visualize this and its bothersome. But we are making progress and its fun to continue along our way to clearer and clearer pictures of our lovely universe (observable or otherwise).

 

[TalonD]

If it is infinite and flat then there would be no center. If it is closed then it would be an analog of a 2d surface of a sphere and there would still be no center anymore than you could say that the surface of the Earth has a center. The volume does but not the surface. Or perhaps you could say that every point is a center since it is equidistant from a point on the opposite side of the spherical surface. Or you could say that every point is a center because it is equidistant from it's maximum observable horizon. It all depends on your definition of 'center' doesn't it?
Every observer is at the center of his or her observable universe. My center is offset from yours by so many miles depending on where we each live so my observable universe overlaps yours. In a way.. that almost seems holographic. However, if we are sufficiently far apart then our individual observable universe horizons would not overlap.

What confuses the average layperson. Is that what we directly observe is a three dimensional volume and all of our everyday experience tells us that three D volumes are finite and have a center. But the universe doesn't necessarily have to be that way, and that isn't something that is obvious to the average joe, it is counterintuitive.

 

[Galteeth]

Ok, this may be a dumb question, but hypothetically, if it was found that the entire universe was rotating, would the axis along which it was rotating constitute a center?

 

[TalonD]

rotating relative to what?

two rotational axes would be needed to define a center

 

[DaveC426913]

Ok, this may be a dumb question, but hypothetically, if it was found that the entire universe was rotating, would the axis along which it was rotating constitute a center?

There has been much discussion and research about a rotating universe. Not sure what the general consensus is these days.

 

[ViewsofMars]

Dr. Marc from the National Aeronautics and Space Administration (NASA) said, "Now we know that not only are we humans not at the center of the universe, but there is no center of the universe!"
http://spaceplace.nasa.gov/en/kids/phonedrmarc/2003_june.shtml

 

[chronon]

Ok, this may be a dumb question, but hypothetically, if it was found that the entire universe was rotating, would the axis along which it was rotating constitute a center?

Gödel's rotating universe model doesn't have a specific axis of rotation.

 

[ray b]

the universe can do what ever it wants
we know far too little currently to limit it

we here are unable to tell if there is a center or edge
if the universe rotates or has proper motion
that is not to say does or doesnot
we just can not tell yet

but almost every thing in the universe moves and rotates

 

[petm1]

I think that the center connection of mass is the direction to the universe's beginning, this makes every point particle the center of its own universe, but not "a" single center to be found in space only in time.

 

[JnWaco]

Pardon me, I'm nowhere near as smart as the dumbest one of you guys, being I'm not a scientist, but is Hubble's "constant" (Ho) uniform in every direction from the Earth?

I'd like to point out that physics and cosmology are a recent interest in mine, though I have no scientific training beyond college calculus II and the basic physics courses (I'm a CPA). Thanks for letting a novice participate.

 

[Chaos' lil bro Order]

Its a good question. As far as I recall from about 5 years ago the constant was 71km/hr/mpc and the plot of galaxies used held to this quite well for all directions. But maybe and expert can give a better answer here.

Pardon me, I'm nowhere near as smart as the dumbest one of you guys, being I'm not a scientist, but is Hubble's "constant" (Ho) uniform in every direction from the Earth?

I'd like to point out that physics and cosmology are a recent interest in mine, though I have no scientific training beyond college calculus II and the basic physics courses (I'm a CPA). Thanks for letting a novice participate.

 

[JnWaco]

Its a good question. As far as I recall from about 5 years ago the constant was 71km/hr/mpc and the plot of galaxies used held to this quite well for all directions. But maybe and expert can give a better answer here.

Thanks!