For you and me, the question is relatively straightforward—it’s what keeps our feet on the ground, computers on our laps, and water in our glass. But for physicists, it’s not that simple.

Gravity forms the foundation of general relativity, the theory that much of modern physics is built on. It warps spacetime and allows galaxies, stars, and planets to form. It’s helped us make sense of the universe, but it’s also hard to reconcile with quantum mechanics, the leading theory that describes most of what general relativity doesn’t—the really small stuff.

Physicists have been searching for years for ways to get gravity to agree with quantum mechanics. That search has produced string theory, causal dynamical triangulation, and others which seek to break gravity down into its component parts. Now, Stefano Liberati of the International School for Advanced Studies and Luca Maccione of Ludwig Maximilian University think they have a better approach.

Spacetime, they say, can be understood as a liquid. A superfluid, really, composed of fundamental objects we may not have discovered yet. Spacetime’s properties then emerge, like water, which has emergent properties like fluidity and cohesion when H 2 O molecules are grouped together at the right temperature and pressure.

Clara Moskowitz, reporting for Scientific American: