Why haven’t we found aliens? A physicist shares the most popular theories. | Brian Cox

Chances are, we’re not alone in the universe. But if that’s true — why can’t we seem to find our neighbors? This question is known as the Fermi paradox, and it continues to go unsolved. However, some theories could offer potential solutions. Physicist Brian Cox explains the paradox and walks us through our best guesses as to the reason for our quasi-isolation. 0:00 Who is Enrico Fermi? 0:22 What is the Fermi Paradox? 1:29 Rare Earth Hypothesis 2:41 Extinguished Civilizations 3:51 Technological Singularity 4:34 Vast Distances 5:14 Cosmic Quarantine 7:31 The Great Filter 9:51 The Great Silence ---------------------------------------------------------------------------------- Go Deeper with Big Think: ►Become a Big Think Member Get exclusive access to full interviews, early access to new releases, Big Think merch and more.