[James]

Fermi paradox questions why we have no evidence of alien intelligence given the universe is billions of years old, and it would only take a fraction of that time for a sufficiently advanced civilisation to traverse, say, the Milky Way galaxy. Maybe we are the only instance in the universe of life or intelligence starting? We can't rule that out.

Generation ships or Self-replicating machine ships might be the best hope of travelling to other galaxies if faster-than-light type travel is not possible.