Scientist proposes wild explanation for why we haven't discovered aliens yet

We know our galaxy is huge, and that there’s an untold number of other galaxies out there in the unimaginably large universe. We also know that there’s bound to be plenty of planets in those galaxies, and at least a portion of them are bound to be habitable by some form of life. So, why haven’t we detected, spotted, or at least heard the faint whispers of another intelligent civilization outside of Earth? A planetary scientist from Colorado’s Southwest Research Institute believes he might have the answer, and it’s literally chilling.