Fine ; Atlantic Ocean to stone age man. In hindsight, sure, boat development was coming along and it was only a matter of time. But you take the average stone

Fine ; Atlantic Ocean to stone age man. In hindsight, sure, boat development was coming along and it was only a matter of time. But you take the average stone age man, and tell him that you can sail (or fly) across the ocean one day to another land - that's the sort of leap of faith we require now to believe in interstellar travel. Sure the distances are bigger than any analogy, but distances are just a function of speed. At the moment, it can't be done, so we have to rely on some nebulous concept of 'in the future the technology will be developed'. I want to say 'can't be done' but such challenges continually get overcome by the relentless march of technology. So I have to say 'can't say can't'. Thus it messes with my head.