139 Where is the center of the Universe?
Description
This article is from the Astronomy FAQ, by Joseph Lazio (jlazio@patriot.net) with numerous contributions by others.
139 Where is the center of the Universe?
Often when people are told that galaxies are receding from us, they
assume that means we are at the center of the Universe. However,
remember that the Universe is homogeneous and isotropic. No matter
where one is, it looks the same in all directions. Thus, all galaxies
see all other galaxies receding from them. Hubble's relationship is
compatible with a Copernican view of the Universe: Our position is not
a special one.
So where is the center? *There isn't one*. Although apparently
nonsensical, consider the same question about the *surface* of a
sphere (note the *surface*). Where's the center of a sphere's
surface? Of course, there isn't one. One cannot point to any point
on a sphere's surface and say that, here is the center. Similarly,
because the Universe is homogeneous and isotropic, all we can say is
that, in the past, galaxies were closer together. We cannot say that
galaxies started expanding from any particular point.
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