Back reaction observed for the first time in simulation of black hole in water tank

Scientists have revealed new insights into black hole behavior with research showing how to simulate a phenomenon called backreaction.

The team from the University of Nottingham has used their simulation of a black hole, with a specially designed water tank, for this latest study, published in Physical Review Letters. This study is the first to show that the evolution of black holes due to the fields around them can be simulated in a laboratory experiment.

The researchers used a water tank simulator consisting of a draining vortex, like the one created when you pull the plug into the bath. This mimics a black hole, since a wave that gets too close to the drain will be dragged through the plug hole and cannot escape. Systems like these have become increasingly popular over the past decade as a means of testing gravity phenomena in a controlled laboratory setting. In particular, Hawking radiation has been observed in an analog black hole experiment with quantum optics.

With this technique, the researchers showed for the first time that when waves are sent into an analog black hole, the properties of the black hole itself can change significantly. The mechanism underlying this effect in their particular experiment has a remarkably simple explanation. When waves come close to the drain, they effectively push more water through the plug hole, decreasing the total amount of water in the tank. This results in a change in the water level, which in the simulation corresponds to a change in the properties of the black hole.

Lead author, postdoctoral researcher Dr. Sam Patrick from the University of Nottingham School of Mathematical Sciences explains: “For a long time it was unclear whether the reverse reaction would lead to measurable changes in analog systems in which the fluid flow is driven, for example by using a water pump. We have shown that analog black holes, like their gravitational counterparts, are intrinsically reactive systems. We have shown that waves moving in a draining bathtub push water through the plug hole, significantly altering the discharge rate and the effective attraction of the analog. black hole.

What really stood out to us is that the back response is strong enough to cause the water level to drop across the system so far that you can see it with the eye! This was really unexpected. Our study paves the way to experimentally investigate interactions between waves and the spacetime through which they move. This kind of interaction is crucial, for example, for investigating the evaporation of black holes in the laboratory. “

Black hole research at the University of Nottingham has recently been awarded a £ 4.3 million grant for a three-year project that aims to provide further insight into the physics of the early Universe and black holes.

The research team will use quantum simulators to simulate the extreme conditions of the early Universe and black holes. The Nottingham team will use a new state lab to set up a new hybrid superfluid optomechanical system to mimic quantum black hole processes in the lab.