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Reverted edits by ByronCavanaugh123 (Talk) to last revision by Jpatt
The size, shape, and age of the universe, as well as how it began, are, however, all points of contention.
The size, shape, and age of the universe, as well as how it began, are, however, all points of contention.
== Shape ==
The common view among [[cosmology|cosmologists]] is that the universe is a four dimensional Riemannian [[manifold]] whose spatial part of the metric is increasing over time. This is interpreted as an expansion of the universe.
Imagine you are at a random spot on a spotted balloon, when someone inflates the balloon you'll see the spots moving away from you, so it would seem you are at the center of the expansion.
Furthermore, the further away the spots are the faster they move away from you.
This is also true for the universe: the more distant a [[galaxy]] is, the faster it moves away from us.
Further imagine that you are a creature that only exists in two dimensions.
That is, you have width and depth, but no height.
So living on the surface of the balloon, you cannot see the shape of the balloon itself.
If you went for a walk in a straight line, you would actually go around the balloon and end up where you started, despite not being aware that you were travelling in a circle.
The theory goes that the three dimensions of our universe that we can see are like the two dimensions of the surface of the balloon, which wraps around on itself in another dimension, so that if we travelled through space in a straight line, we would eventually return to our starting point. The fourth dimension is [[time]] and [[String theory]] holds the universe exists right up to [[The Tenth Dimension|ten dimensions]].
One consequence of this idea is that the universe therefore has no edge (just like there is no edge to the surface of a balloon) and therefore no center.
Thus for any location in space, it would appear that that location is at the center of the expansion of the universe.
Thus for any location in space, it would appear that that location is at the center of the expansion of the universe.
==External Links==
*[http://www.relativitycalculator.com/models_universe.shtml Early Models of the Universe]
==References==
==References==
{{reflist|2}}
{{reflist|2}}
[[Category:Astronomy]]
[[Category:Astronomy]]