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Q & A: size and age of the universe

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Most recent answer: 09/07/2009
Q:
Question about age and movement of universe. If the theory of the universe being 15 billion( or is it trillion) years old is correct than how is the universe 80 billion (or is it trillion) light years wide? Would this mean that matter can exceed the speed of light?
- John (age 13)
Cincinnati, Ohio
A:
The standard picture is that our universe descends from a Bang 13.7 billion years ago. There are many detailed lines of evidence which all lead to the same conclusion. Whether this event was unique or one of a sequence of Bangs, we don't know. Surprisingly, we expect to get good evidence on that question (from the statistics of the variations  in the left-over radiation and from its polarization fluctuations) over the next few years.

As for the size of the universe, we do not even know whether it is finite or infinite. The new evidence may point to a picture in which it is infinite, or to one where either possibility could occur. In General Relativity there is no speed limit on how fast distant regions can recede from us. The speed limit applies to local events.

Mike W.

(published on 09/07/2009)

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