( it's still strange, to him, that people don't just know. first contact was well before his lifetime, and though marietta, georgia wasn't a beacon of diversity while he was growing up, aliens have always been normal to him. so his expression is rueful, when he says: ) Not on Mars, unless you count the colonies. We had to go a bit further out, and truth is they got to us before we got to them.

But, yeah. Lots of other civilizations, and species. Languages and sciences and god knows what else, all different for each kind of people.