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The Question

(Submitted March 28, 1997)

It seems that it doesn't make sense to think of the Universe as having either a center or an edge, but does it then make at all sense to think of it as having any kind of dimension or size? Perhaps the Universe contains all sizes and therefore has no sizes. Perhaps I've been reading too much about Richard Gott and this very bizarre de Sitter space.

The Answer

You are right that it doesn't make sense to think of the Universe as having an edge. It is better to think of the Universe as the surface of a balloon, with the stars and galaxies on the that surface.

However, we can still think of the Universe as having size and dimension. Indeed, the Universe does contain all sizes, but it too has a size, just as the balloon has a size. Physicists raise questions about the number of dimensions, and have theories for the Universe consisting of 11 dimensions. This, plus more familiar concepts such as the curvature of space-time, may make it difficult to think about the Universe having a size. But none the less, we consider that it does.

Jim Lochner
for Imagine the Universe!

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