Why a tiny gravity measurement may be a leap forward for physics Premium

In a clever experiment, scientists measured a force of around 30 attonewtons on a particle with just under half a milligram of mass.

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 researchers say the work could “unlock more secrets about the universe’s very fabric” and may be an important step toward the next big revolution in physics.

But why is that? It’s not just the result: it’s the method, and what it says about a path forward for a branch of science critics say may be trapped in a loop of rising costs and diminishing returns.

From a physicist’s point of view, gravity is an extremely weak force. This might seem like an odd thing to say. It doesn’t feel weak when you’re trying to get out of bed in the morning!

Still, compared with the other forces that we know about – such as the electromagnetic force that is responsible for binding atoms together and for generating light, and the strong nuclear force that binds the cores of atoms – gravity exerts a relatively weak attraction between objects.

And on smaller scales, the effects of gravity get weaker and weaker.