A brake made of light slows a molecule's spin 300,000 times over

Inside every molecule, parts jitter and spin at random, driven by heat — and building tiny machines means learning to control that motion. At IOCB Prague, scientists built a molecule with two parts: a light-driven motor and a rotor that spins freely. Shine light, and the motor changes shape, physically blocking the rotor — a brake. Previous systems could change a rotation rate by at most a factor of 100; this one slows it about 300,000-fold, reported in Angewandte Chemie International Edition. At very low temperatures, a braked rotor that would spin once a second unbraked would take some 350 billion years to turn once — about 25 times the age of the universe. 'Having a motor alone is not enough,' said researcher Kaleta. 'You also need elements that can regulate the motion.' Now they exist.

SDG 9 · Industry, innovation and infrastructure — Mechanism: tech innovation