Astronomy/universe

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Question
how old is space

Answer
Our Universe was formed a little less than 14 billion years ago (calculations of the exact age involve some assumptions about the 'shape' of space, but it is certainly between 13.7 and 13.9 billion years old).

For a reasonably clear though somewhat dated discussion of the age, see The Expansion of the Universe (at http://cseligman.com/text/galaxies/universe.htm ). At the time it was written, 10 to 15 years ago, long-term efforts to pin down the age were just starting to go from "between 10 and 20 billion years" to "around or a little less than 15 billion years". Not long after that page's most recent update, the number was pinned down to the more specific numbers in the first paragraph. In fact, most discussions give very 'precise' ages similar to 13.73 or 13.84 billion years, implying an incredible improvement in accuracy; but as noted in the first paragraph the actual number depends upon some assumptions about exactly how the Universe works, so although individual numbers tend to be very exact, the correct number is uncertain by a few tens of millions of years. Still, to someone following the field since the mid 1900's (as I have), the current precision feels barely short of miraculous.

Though perhaps beyond the scope of your question, you might also find the brief notes about The Observable Universe (at http://cseligman.com/text/galaxies/expansion.htm ) of some interest.  

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Courtney Seligman

Expertise

I can answer almost any question about astronomy and related sciences, such as physics and geology. I will not answer questions about astrology and similar pseudo-scientific rubbish.

Experience

I have been a professor of astronomy for over 40 years, and am working on an online text/encyclopedia of astronomy, and an online catalog of NGC/IC objects.

Publications
Astronomical Journal, Publications of the Astronomical Society of the Pacific (too long ago to be really relevant, but you could search for Courtney Seligman on Google Scholar)

Education/Credentials
I received a BA in astronomy and physics and a MA in astronomy, both from UCLA. I was working on my doctoral dissertation when I started teaching, and discovered that I preferred teaching to research.

Awards and Honors
(too long ago to be relevant, but Phi Beta Kappa and Sigma Xi still keep trying to get me to become a paying member)

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