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The Milky Way Thinks It’s Been Alive for 22.5 Minutes
Light speed is agonizingly slow, but maybe for a galaxy that’s OK
As far as we can tell, light is the fastest thing in the universe. Indeed, it seems pretty quick to us humans. It might as well be instantaneous at sub-planetary scales.
Most of you probably know that light would circle the earth about 7.5 times per second (if it could curve like that), and that sunlight takes 8 minutes to reach Earth. That might not seem like a long time to travel such vast distances — but those distances aren’t actually vast at all.
If you were an organism the size of a galaxy, light might seem unbearably slow.
It’s not exactly clear what the diameter of the Milky Way is. The accepted value was 100,000 light years for a long time, but more recent studies have suggested it may actually be 150,000 or 200,000 light years across. The density of stars probably decreases gradually as you go farther out, so it might be a somewhat arbitrary distinction. For the purpose of my calculations, I’ll use…
