How Can Any Object Be 28 Billion Light Years Away?
by Scott Teresi
With the commonly-accepted age of the universe set at 14 billion years, though (give or take a few billion), how could light have ever reached us from an object 28 billion light years away? Heres what happened. When the quasar was less than a billion years old it emitted toward earth (or where earth would eventually be) the light were seeing now. In the intervening 13 billion years, space actually expanded between the earth and the quasar so much as to move the two objects apart at a rate of almost twice the speed of light. Now, after a total of 14 billion years, the quasars light has finally reached us and we find ourselves 28 billion light years from its source.
You may be puzzled as to how two objects can actually recede from each other at twice the speed of light. Nothing can travel faster than light, right? Well, the earth and the quasar were never actually traveling anywhere near the speed of light. Instead, the intervening space between the two objects was expanding so much as to make it seem like thats what was happening. The universe has been expanding since its birth at the Big Bang. To this very day, the space between galaxies everywhere is expanding. The objects arent being pushed or pulled apart; the actual fabric of space between them is expanding. Space can expand at whatever rate it wants, actually. Meanwhile, however, no object will ever move through that space at faster than the speed of light.
Sloan Digital Sky Survey web site.
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