does the univers have a special shape?

Question

does it have a center ?

Answer 1

There are two big bang universes: known and unknown, togther they make up the entire universe resulting from the BB. The known universe is 14-15 billion light years in radius and the hub of that radius is you. Well, maybe not you specifically, but Earth is at the hub, which makes it the center of the known universe.

[Note, there is a third universe as well. I call this the null universe which preexisted the BB and contained nothing (null). Presumeably the null universe still exists outside the BB universe. If we know nothing about the unknown universe, we really know nothing about the null universe.]

The reason we sit at the center of the known universe is because we see what light has been bringing to us from all around us since the big bang. The BB occurred 14-15 billion years ago and light (photons) occurred within a few seconds of the BB. So light has been coming to us for 14-15 billion years, which is why we can only see out to a "rim" 14-15 billion light years away.

It is true the known universe is expanding and accelerating in that expansion. The Hubble red shift shows that. But that does not mean the known universe has a central point around which it is expanding.

Think of the known universe as a circular area on the skin of an expanding balloon. Inside the area, imagine some dots representing galaxies. As the balloon expands, its surface area increases drawing the dots, the galaxies, apart. Thus, they are getting farther apart without moving away from some center in our known universe. But is there another place where a center exists?

If the balloon model has some validity, the center of the universe, where the BB occurred, lies outside our known universe. It lies in the unknown part of the universe...the center of the balloon so to speak. But, because it is unobservable, the universe outside our known universe remains unknown; so we can only guess what its real shape and size might be.

On the other hand, the expanding balloon model does help us explain what we can see. For one thing, although the known universe is flat like a pancake, and that seems to be the consensus nowadays, it is not perfectly flat. That is, it has a wee bit of a curve, just like the surface of a very very big balloon would have.

If the wee bit of curve is the arc of the entire universe, then the radius to the center of the whole universe (the entire balloon), including the known and unknown, would be at least 14-15 billion light years as well. Why...because that's when the BB occurred and the "balloon" has been expanding ourward every since.

Now here's the fun part. I wrote "at least" because, shortly after the BB, most astrophysicists agree, there was a so-called inflationary epoch. During this epoch, the universe actually expanded faster than light speed. In which case, the radius of the whole universe would be greater than 14-15 billion light years. How much greater I have no idea.

One final note, the balloon model is not mine. It is a commonly used model; so I have no idea who the first one of authority used it. But Greene [See source.] uses it and it seems to explain a lot of the mysteries so we can grasp them.

But it does not explain one mystery: why is the known universe flat? Another way to put this, why can we not see into the center of the entire universe, or close to it?

Light has been traveling since the BB (or close to it); so the light near the big bang should have arrived on Earth. But apparently it hasn't since our known universe is flat and not conical shaped with the tip of the cone reaching back to the source of the BB. And that mystery is not explained by the balloon model.

Answer 2

Nobody really knows. Contrary to popular belief, Hubble's observations DO NOT mean that there must be a centre of the universe that everything is receding from. Rather, he observed that on a global level, everything is moving away from everything else, and the greater the distance between two objects, the faster they were receding from one another.

While at first this may seem impossible, it is not necessarily so. In particular, it suggests that the Universe has more than 3 spatial dimensions. In order to understand why, consider a balloon with dots on the surface to represent galaxies. As the balloon inflates, the dots move away from one another, but not do not move away from a single point on the surface. Instead, the move away from a single point in the centre of the balloon.

This shows that a global recession of objects in two dimensional space can be explained by a recession in three dimensional space. This can then be expanded to show that a global recession in three dimensional space may be caused by a recession in a higher dimension.

The balloon model also illustrates another point about the possible shape of the universe. In particular, the surface of the balloon is unbounded, but finite. This means that even though the balloon does not have an infinite surface area, there would be no sudden end to the surface if you were to travel along it. Similarly, this may be the same in the Universe.

Various physical theories give different numbers of dimensions and shapes for the Universe, but as of yet, nobody knows which is correct. It may be that we can never know for certain.

Answer 3

Just because the universe is expanding does not imply things are flying out from a central point. It's more like a continuously increasing enlargement of a photograph. Everything is getting farther away from everything, not just from one point.

All I've heard about the shape is that matter seems to be clumped up as if on giant sheets like bubbles with tremendous empty voids between them. Does that count as a 'shape'?

Answer 4

well as far as we know it has a center, as Hubble observed that all objects are traveling away from a central point. It should be spherical if this is the case, but some conjecture that it is a hyperbole. What we know about out universe is kind of like trying to figure out the shape and size of the ocean with only being able to obseve it from a fixed point on the ocean floor.

Answer 5

The universe is an abstract form; it has no shape or center.

A good example that I've read is that the universe is like the surface of a ball. The surface has no center. The ball itself has a center, but its surface alone has no middle.

Answer 6

The Universe ,according to Einstein ,is a Finite structure hav
ing a particular volume in its contaiment.
In accordance to the laws of Geometry all volumes irespective of their shape have a center of mass as well as a geometrical Center.
If someone tells you that the Universe has no center ,he would be talking out of the top of his hat.

Answer 7

Freidmann equations describe universe as homogeneous and isotropic. there's a factor of Gaussian curvature in the eqn that refers if the factor is positive, universe is hyperspherical, factor be 0 for universe is flat, factr be negative for universe is hyperbolic.