What Is Space, Exactly?

We inhabit a 3D world with space all around us: I’m here, you’re there and there’s a distance separating us. But what really is is that seperates us?

Think a little more deeply about it, and you’ll realise that the distances certainly aren’t fixed — travel fast enough, and they appear smaller. This video explains how three competing theories for the theory of everything describe exactly what space is. [YouTube]