In the years since, astronomical observations have provided substantial support for the cosmological principle, but only if you examine space on scales at least 100 million light-years across (which is about a thousand times the end-to-end length of the Milky Way). If you take a box that’s a hundred million light-years on each side and plunk it down here, take another such box and plunk it down way over there (say, a billion light-years from here), and then measure the average overall properties inside each box—average number of galaxies, average amount of matter, average temperature, and so
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