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Jan30-10, 11:11 PM
P: 5
Perhaps we can offer an easier explanation. Using the most powerful telescopes, we are capable of observing galaxies 10 to 13 billion light years away. But the "horizon" of visibility in the cosmos streches more than just some 20 to 26 billion light years because space itself is expanding. So the edge of the observable universe must be at least 46 billion light years away from us (called the comoving distance or the partical horizon). The visible universe, however, is most likely a sphere of 93 billion light years.