JEREMIAS PFAFF: THE BOUNDARIES OF QUANTUM PHYSICS

Jeremias Pfaff speaks to All About Space about what it takes to measure gravity on such a minute scale. The next step? To go even smaller

- Daisy Dobrijevic

Why can’t physics describe how gravity works at a subatomic scale?

It might be able to, we just don’t know yet. That’s why we did this experiment, because it’s mainly an experimental issue. Firstly, it’s just really difficult to measure gravity. It’s such a small force; you can imagine the gravity between the two spheres that we measure is 30 billion times smaller than the gravity that Earth pulls on one of the spheres. Just measuring that small force is tricky because you also have to shield it from all the other forces, such as magnetic and electrostatic, that are much stronger. If you can imagine a paperclip, the whole Earth is pulling on it, but just a little magnet is able to pull it up against the gravity of Earth – that’s how much stronger the other forces are. It’s just really difficult to measure on a small scale, so nobody has done it yet.