For decades the Fermi Paradox has stipulated that unless life is unique to Earth, it must exist throughout the galaxy. And yet, so far there's been no word. Hence, paradox. A new theory, based on natural selection, might explain why.
According to paradox-smasher Adrian Kent of the Perimeter Institute in Waterloo, Ontario, aliens (should they exist) are probably competing for resources (viable planets) on a galactic scale, much like we earthlings do for mall parking spaces around the holidays.
If that violent theory is true, then natural selection would favour the quiet species, he says, as those aliens who "lay low" or lack ambition would probably skirt by unnoticed. Noisy species, like us for example, would attract the attention of a more advanced species, who would in turn arrive to conquer and pillage the spoils of war.
Personally, I think I'll just stick to the theory that vast distance, paired with the cosmic speed limit (speed of light) and cosmic microwave background radiation's knack for hiding interstellar comms signals all account for E.T.'s inability to be heard here on Earth. Much tidier that way. [New Scientist]