We can argue that interstellar travel is slow and expensive, that ETCs haven’t reached us because there hasn’t been enough time for them to reach us. Equally, we can argue that interstellar travel is fast and cheap for a civilization with a sufficiently advanced technology. Personally, I’d like to think that our descendants would think of ways to explore the Galaxy under reasonable timescales. And if we were able to do that, so could others in the past.
