I think your sibling poster has it right: lack of evidence. All the speed of light problems can be ameliorated. The entire galaxy could be visited (if not colo

I think your sibling poster has it right: lack of evidence. All the speed of light problems can be ameliorated. The entire galaxy could be visited (if not colonized) in a relatively short amount of time by something like a Von Neumann probe at even 0.01c. The 'aliens' needn't be biological.