The Universe Expanding ?

Question

If the universe is not infinity in size but comparable to walking on a sphere ie Earth as there in no end. How does this work as the Earth has mass below its surface so is the universe like the skin of a sphere if so whats under its sphere shape.

Or if im wrong explain to me how its meant when comparing the infinity of the expanding universe to a surface of a sphere.

Or if not that also explain to me the infinity of the universe expanding as because right now I simply think its expanding in all directions for infinity pointing to a center where the big bang occurred im sure there is no centre to the universe so my thought it wrong

Answer 1

A sphere's surface is two-dimensional; you can go left/right or back/forth (or any combination). But no other direction. The Universe is three-dimensional; you can go left/right, back/forth and up/down (or again, any combination). It can be a difficult shape to imagine, but it's like traveling on a sphere, but in any possible direction.

And since it's space itself that's expanding, there is no 'center'. The Big Bang literally occurred everywhere. Just as there is no center to the surface of the sphere, there is no center of the Universe.  

Answer 2

The universe is a three-dimensional space, but distorted by the mass in it so that the ends curve around and join up at the other side. This means that the universe is finite, but there's nothing outside of it.

It's like computer screen in some computer games (such as the classic Pacman). When the creature goes off the left side, they reappear on the right. When they go off the bottom, they reappear at the top. As far as that little creature is concerned:

1. The screen is finite but there are no boundaries. You can go on as far as you like in any direction.

2. There's no centre to the screen, as all points are the same.

Answer 3

Actually we don't even know enough about the shape of the Universe to affirm that the Universe is infinite or not.

Suppose we put an ant on a infinite sheet of paper. The ant is short-sighted and sees only that close to him his universe look pretty flat. If he starts walking he will never meet a boundary and never come back to the same place again. The two-dimensional plane is infinite and without bounds.

Next put the ant on a large sphere. Again our ant can not see far enough to observe any curvature. If he starts walking in one direction he will never come to a boundary, but this time he can make a roundtrip. The spherical universe is unbounded but finite.

We are in the same position as the ant, but in three dimensions. Locally our Universe seems flat and unbounded, but we don't know if we are in the 3 dimensional equivalent of the plane or the sphere. In the first case the Universe would be infinite, in the second place it would be finite.

Now the fun and speculation starts....

Even weirder shapes are possible. In two dimensions our ant has a third possibility, a universe shaped as a torus or a donut. We can make a torus by taking a sheet of paper, roll it up in a cylinder and then glue the two open ends together.

The torus also has a three dimensional equivalent. Take a cube and imagine the following rule: everytime we leave the cube-universe through a side, we immediately enter it again to the side opposite. It is as if the opposing sides are glued together.

Strange? Yes, but not excluded...

My current favourite shape for the Universe is the following. Think of *two* three dimensional spheres. We live inside one of the spheres. A spaceship that flies to the boundary of one sphere immediately reappears on the corresponding point on the boundary of the other sphere and continues its voyage there. It is as if the boundaries of the two spheres are somehow glued together.

Neat, isn't it?

Answer 4

'Scuse me while I kiss the sky.............

Answer 5

the only answer i know is that nobody knows how long space goes on for because if you get further then mars you're basically dead (by rocket ship) but the satellite has been going around for years but has not seen anything beyond our universe

Answer 6

the universe is sure expanding. the universe cannot be compared to a sphere. if you do, then walking all around the universe, you will come at the point you had started from, and that is not possible.

after big bang, the universe is expanding and some say that it will be expanding for ever.

speaking of centers, every thing does have a centre (that is the centre of mass), and so does the universe. using simple logic, we might say that the point where the big bang occured is the centre, but its a whole lot complicated.