You're unlikely to ever run into a black hole, but here's what it "looks" and "sounds" like when two black holes run into each other. The movie shows a simulation of the gravitational waves generated when two black holes collide and form a third, and the sound file shows what these waves would sound like if you cold hear them.
Over the last few years the words string theory have nudged their way into public consciousness. It's a theory of everything in which everything's made of strings — or something like that. But why strings? What do they do? Where did the idea come from and why do we need such a theory? David Berman has an equation-free introduction for beginners.
In the last issue Lewis Dartnell explained how chaos on the brain is not only unavoidable but also beneficial. Now he tells us why the same is true for our solar system and sends us on a journey that has been travelled by comets and spacecraft.