Though physicists have competing ideas of what quantum gravity could be like, they have yet to definitively determine whether the gravity that we experience is quantum at all. A new proposal lays out a way to dispute or affirm this by observing whether a quantum object’s state is affected when its gravity is measured.

Physicists have repeatedly shown that tiny objects are subject to quantum effects, but for large objects whose behaviour is highly affected by gravity – with black holes being the most extreme example – the same…