Technology keeps making things smaller, but this is ridiculous. Scientists at Rice University in Houston have just made a tiny submarine with a molecular motor. They call it a unimolecular submersible nanomachine (USN), because it is composed of a single molecule made up of 244 atoms. The really smart bit comes from how it is driven: when the molecule absorbs a photon of light, one of the bonds that holds it together becomes more flexible, and the tail spins a quarter of a rotation to attach to another atom and reach the preferred lower energy state. This motion moves the molecule, and the process repeats. This happens millions of times a second.

I wouldn’t put down a deposit on a nanosub quite yet, though: the motion is random, as there is no way to steer the molecule at present. The researchers figured out that it behaves this way by analyzing the way that the molecule diffuses, because these molecules diffuse 25 per cent quicker with the light source than without.  Nope, not very practical, but it is a neat bit of molecular hackery.