Ask Ethan: How Close Could Two Alien Civilizations Get To One Another?
“What’s [the] closest two, independent intelligent civilizations could be, ignoring interstellar travel and assuming they develop in different star systems and follow roughly what we know as ‘life’? Globular clusters can have a high density of stars, but does too high a density rule out habitability? An astrophysicist in a dense cluster would have a much different view of the universe and the search for exoplanets.”
Okay, so you have a planet that has the right ingredients for life, and everything has worked out according to your wildest dreams. We’ve developed life, it’s thrived for billions of years, and now we’ve reached the point where we’ve got an intelligent, technologically advanced civilization, just like we do here on Earth. Let’s imagine we’ve got multiples, now, throughout the Universe. What’s the closest two independent ones could possibly be? Should we look in the same solar system? In a globular cluster? In the galactic center? In a spiral arm? In an open star cluster? Or should we just wait for another one to pass close by in interstellar space?
The science is open to all of these possibilities, but some of them are strongly disfavored based on the evidence we have. Come find out how close two alien civilizations could get to one another on this edition of Ask Ethan!