The fine folks at BBC’s Horizon series have previously explored such intriguing topics as the nature of reality, the age-old tension between science and religion, how music works, the volatile history of chemistry, and what time really is.

In How Long is a Piece of String?, they enlist standup-comic-turned-physics-enthusiast Alan Davies in answering the seemingly simple question of the film’s title, only to find in it a lens — a very blurry lens — on the very fabric of reality. Along the way, Davies asks some of the world’s top scientists to measure his piece of string, gets repeatedly discombobulated by mathematician Marcus du Sautoy (he of The Number Mysteries fame), and turns to quantum mechanics to try to work out where the individual atoms and particles that make up the string actually are. The result is as enlightening as it is entertaining.

Your string does not actually possess a length. Somehow, by measuring it, we create a length for the string.

The matter of everybody in the world, the whole of the human race, amounts to a sugar cube. The rest is just space.

Reality, in some sense, does not exist unless we’re actually observing it. And it’s our act of observation that makes things real.

For a deeper dive into these most fascinating frontiers of human thought, you won’t go wrong with Brian Cox’s The Quantum Universe: Everything That Can Happen Does Happen.

↬ @kirstinbutler