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How do experts calculate and interpret large distances in the universe?
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May 16th, 2011
Lets say we are talking about this far-away galaxy A. We are say it is 13.2 billion light years away from us.
Are we saying that
the galaxy is 13.2billion light years away from us right now?
Or we are saying that
(2) the light from this galaxy as we see it now has traveled for 13.2 billion light years before reaching us.
If it is the latter case, that means we don’t know where that galaxy is right now(that is, of all things, we don’t know how far away it is right now, we only know it was 13.2billion light years away 13.2billion years ago, which then means that the universe was atleast 13.2 billion light years across in size. But that would mean that universe was 13.7billion light years across in size if we see something that we say is 13.7 billion light years away from us).
In any case, how did they (the experts) calculate this distance?
Using Fluther
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