“Youth is the gift of nature, but age is a work of art.” –Stanislaw Jerzy Lec
You’ve heard it said many times here: the Universe, since the Big Bang, is 13.8 billion years old. But how do we know this to be true?
Image credit: Bock et al. (2006, astro-ph/0604101); modifications by me.
Moreover, how many different lines of evidence do we have that leads us to this conclusion? Is it like it is for dark matter, where we have a whole slew of them? Or are there only one or two...