in reply to basic doubt
Please peruse the PerlMonks FAQ. In particular, I draw your attention to How do I compose an effective node title?.
There is no Extraterrestrial life
There aren't any suitably capable Extraterrestrials
Interstellar travel is too difficult
We're too uncool / not worth the trouble
What do you mean they haven't visited?
Results (560 votes). Check out past polls.