I think this is an interesting thought experiment. Given the sheer number of stars, and by extension, planets in the galaxy (much less the universe), it seems probable that life exists elsewhere. How common it is, who knows? That is of course an important unknown variable in Drake's equation.
With the theoretical problems with FTL travel, and the practical issues of subliminal spaceflight, it's probably safe to say that any ET's visiting earth would be far more advanced than we are. Better hope they are benevolent, or that we have nothing they want. As to their possible motivations for visiting, it would likely be the same as ours: curiosity. Were we to detect ET life, would we not want to investigate it?
With all that said, until we gain a greater understanding of the frequency of planets with the capacity to support development of advanced life, the question is highly speculative, if interesting.
A related question that I think is equally interesting: Which is likely to occur first, an earthly visitation by ET life, or human discovery of extant ET life (even if it's microbial)? I think it's probably the latter, possibly even in our own solar system. I hope I live long enough to see us explore that possibility (Europa, for example). I'm not terribly optimistic on that one, considering the state of our space exploration programs, but one can hope.
With the theoretical problems with FTL travel, and the practical issues of subliminal spaceflight, it's probably safe to say that any ET's visiting earth would be far more advanced than we are. Better hope they are benevolent, or that we have nothing they want. As to their possible motivations for visiting, it would likely be the same as ours: curiosity. Were we to detect ET life, would we not want to investigate it?
With all that said, until we gain a greater understanding of the frequency of planets with the capacity to support development of advanced life, the question is highly speculative, if interesting.
A related question that I think is equally interesting: Which is likely to occur first, an earthly visitation by ET life, or human discovery of extant ET life (even if it's microbial)? I think it's probably the latter, possibly even in our own solar system. I hope I live long enough to see us explore that possibility (Europa, for example). I'm not terribly optimistic on that one, considering the state of our space exploration programs, but one can hope.
