Light travels through empty space at just under three hundred thousand kilometers per second, fast enough to circle the Earth seven times in a single second. Nothing carrying information can move faster, and this limit is built into the structure of the universe as described by Einstein's theory of relativity. Even at such speed, the distances of space are vast enough to humble it. Sunlight takes about eight minutes to reach us, light from the nearest star beyond the sun needs more than four years, and the glow of the Andromeda galaxy set out two and a half million years ago.
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