Turbulent black holes

We show that rapidly-spinning black holes can display turbulent gravitational behavior which is mediated by a new type of parametric instability. This instability transfers energy from higher temporal and azimuthal spatial frequencies to lower frequencies — a phenomenon reminiscent of the inverse energy cascade displayed by 2 + 1-dimensional turbulent fluids. Our finding reveals a path towards gravitational turbulence for rapidly-spinning black holes, and provides the first evidence for gravitational turbulence in an asymptotically flat spacetime. Interestingly, this finding predicts observable gravitational wave signatures from such phenomena in black hole binaries with high spins and gives a gravitational description of turbulence relevant to the fluid-gravity duality. Black holes are fascinating objects. They play a funda-mental role in a plethora of energetic phenomena in our universe, for example as the engines of active galactic nuclei, X-ray binaries, and possibly even as regulators of galactic structure. In addition, they have become central tools in the study of field theories through the frame-work of holography [1]. This includes attempts to under