New research has revealed that the accepted wisdom about spacetime not being turbulent could be wrong.
Perimeter Faculty member Luis Lehner explains why it might make sense to treat gravity as a fluid. "There's a conjecture in physics - the holographic conjecture - which says gravity can be described as a field theory," he says. "And we also know that at high energies, field theories can be described with the mathematical tools we use to describe fluids. So it's a two-step dance: gravity equals field theory, and field theory equals fluids, so gravity equals fields equals fluids. That's called the gravity/fluids duality."
Lehner said for many years, the folklore among physicists was that gravity could not be turbulent, adding that the belief was that gravity is described by a set of equations that are sufficiently different from fluid dynamics equations, such that there would not be turbulence under any circumstances.
Lehner highlights the emerging paradox: "Either there was a problem with the duality and gravity really can't be fully captured by a fluid description, or there was a new phenomenon in gravity and turbulent gravity really can exist."
A team of researchers - Lehner, Huan Yang (Perimeter and the Institute for Quantum Computing), and Aaron Zimmerman (Canadian Institute for Theoretical Astrophysics) - set out to find out which.
The team decided to study fast-spinning black holes, because a fluid-dynamics description of such holes hints that the spacetime around them is less viscous than the spacetime around other kinds of black holes. Low viscosity increases the chance of turbulence - think of the way water is more swirly than molasses.
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The team also decided to study non-linear perturbations of the black holes. Gravitational systems are rarely analyzed at this level of detail, as the equations are fiendishly complex. But, knowing that turbulence is fundamentally non-linear, the team decided a non-linear perturbation analysis was exactly what was called for.
They were stunned when their analysis showed that spacetime did become turbulent.