It’s a challenge to see into the ground, but high resolution gravity measurements could be a way to reveal underground structures – caves, tunnels or even water bodies.

Physicists from the Department of Quantum Sciences and Technology tried out this hypothesis at Wee Jasper, near Canberra, well-known for its limestone caves.

Using a commercial gravimeter they could clearly detect caves from above ground; this is a stepping stone to moving to a new-generation of quantum gravimeters, based on ultracold atoms

Quantum gravimeters surpass the classical gravimeter because they have no drift – in the lab the team already have one in development – but not portable yet...