Gravity experiments on the kitchen table: why a tiny, tiny measurement may be a big leap forward for physics

Just over a week ago, European physicists announced they had measured the strength of gravity on the smallest scale ever. In a clever tabletop experiment, researchers at Leiden University in the Netherlands, the University of Southampton in the UK, and the Institute for Photonics and Nanotechnologies in Italy measured a force of around 30 attonewtons on a particle with just under half a milligram of mass. An attonewton is a billionth of a billionth of a newton, the standard unit of force. The...