So conventional by comparison Pasieka/Getty

The black holes in our universe may seem like bizarre, voracious beasts – but stranger ones are possible. Simulations of black holes have revealed the first superfluid specimen.

Superfluids are a form of matter that take mere melting one step further. When a solid turns to a liquid, what was once sturdy and inflexible begins to flow. Superfluids have zero stickiness or viscosity: they can even flow uphill. They also have completely uniform temperature.

But superfluids are extremely difficult to create. Only liquid helium has been coaxed into going superfluid, and then only at temperatures close to absolute zero. The stuff is even harder to study or model: many of the important calculations are ones that nobody knows how to do yet.


Now, Robert Mann at the University of Waterloo in Canada and his colleagues have modelled a theoretical black hole that changes in a way that’s mathematically identical to what liquid helium does when it turns superfluid.

These model black holes are exotic, existing in a higher-dimensional space-time with properties very different from our own. Given certain conditions for gravity’s interaction with matter, the switch to superfluidity could potentially happen in a wider set of black holes – but probably not ones in our universe.

“It’s thinkable that these conditions could be satisfied in our universe, but they’re probably not,” says Mann.

Even so, simulating them is potentially illuminating. “This could tell us something about superfluids which we can’t calculate by other methods, so that’s part of the excitement,” says Jennie Traschen at the University of Massachusetts Amherst.

The other part is exactly the reverse: studying superfluids could teach us about how black holes behave at different temperatures and pressures. “You can see these thermodynamic things happening on the black hole side, and you can learn about them by knowing how thermodynamics works in the everyday world,” says co-author Robie Hennigar, also at the University of Waterloo.

By using one enigma to model another, researchers are inching closer to an understanding of both.

Journal reference: Physical Review Letters, DOI: 10.1103/PhysRevLett.118.021301