If you're a fan of lucid explanations of tricky scientific concepts, it's hard to go wrong with theoretical physicist Brian Cox. But when you mix in physicist Jim Al-Khalili and Simon Pegg, you've got yourself a recipe for pedagogic gold. Also: thinly veiled sex jokes.

In this clip from BBC's A Night With the Stars, Cox recruits Pegg and Al-Khalili to demonstrate the principle of a standing wave in a quantum mechanical context, what this principle can tell us about the discrete nature of atomic energy levels, and why electrons — small as they are — require so much space, when bound to the nucleus of an atom. [BBCHeadlineNews]

Hat tip to Arya!