The conversation usually goes like this:

Do you think we’re alone in the universe?

Answer A) :

No, absolutely not. It’s a huge universe, we’re not at the center or central in any way and it would be the height of vanity to think humans or Earth are in any way special or significant.

Answer B):

We might be. There’s never been any firm evidence of extraterrestrial life, and our galaxy is old enough that intelligent civilizations should have spread everywhere by now.

I’ve lost track of how many times I’ve had this exchange, with scientists, with family, with random people at pubs and (once) on a heavily forested hillside in Norway with a pair of slightly suspicious looking hikers who had probably just hidden a body somewhere. But the fascinating thing is how we tend to fall into either camp A or camp B, and how strongly we feel about our answers.

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