Quantum chromodynamics, the theory of the strong nuclear force, is notoriously intractable. An alternative approach brings gravity to bear, and produces fairly accurate predictions of some physical quantities.

Pluto is no lone ranger in the farthest expanses of the Solar System — its travelling companions now number three. And if Pluto can have so many, why shouldn't other objects in the distant, icy Kuiper belt?

To remain hidden from its host's immune system, the malaria parasite must vary the proteins on the surface of the infected cell. The genes encoding these proteins are very similar, so how does the parasite express just one at a time?