Brian Cox explains the Fermi Paradox and the Great Filter Hypothesis, which could be a key solution to the Fermi Paradox. Brian Cox goes into great detail about the Fermi Paradox, offering explanations for why we have not yet seen evidence of intelligent alien civilizations, even though our galaxy, the Milky Way, contains billions of planets that could support life as we know it.

One possible explanation Brian Cox discusses is the Great Filter, a theoretical barrier that could drastically limit the number of civilizations capable of expanding beyond their home planets. This could mean that life itself is rare, intelligent life is even rarer, or that technological civilizations tend to self-destruct before they reach the stage of interstellar communication.