Feedback first seen in water tank black hole simulation

Scientists have revealed new knowledge about the behavior of black holes through research that demonstrates how a phenomenon called the reverse reaction can be simulated.

The University of Nottingham team used their simulation of a black hole, involving a specially designed water reservoir, for this latest research published in Physical examination letters. This study is the first to demonstrate that the evolution of black holes resulting from the fields surrounding them can be simulated in a laboratory experiment.

The researchers used a water tank simulator that consists of a draining vortex, like the one that forms when you pull on the bath cap. This mimics a black hole because a wave that comes too close to the drain is dragged into the intake hole, unable to escape. Systems like these have become increasingly popular over the past decade as a means of testing gravitational phenomena in a controlled laboratory environment. In particular, Hawking’s radiation was observed in an analog black hole experiment involving quantum optics.

Using 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 dramatically. The mechanism underlying this effect in their particular experiment has a remarkably simple explanation. As the waves get closer to the drain, they effectively push more water into the plug hole, which decreases the total amount of water in the tank. This results in a modification of the height of the water, which in the simulation corresponds to a modification of the properties of the black hole.

Senior author, postdoctoral researcher Dr Sam Patrick of the School of Mathematical Sciences at the University of Nottingham explains: “For a long time it was unclear whether the feedback would lead to measurable changes in analog systems where the fluid flow is driven, for example, by using a water pump. We have shown that analog black holes, like their gravitational counterparts, are inherently reverse-reacting systems. We have shown that waves moving through a draining tub push water into the plug hole, dramatically changing the rate of draining and therefore changing the effective gravitational pull of the analog black hole.

What was really striking for us was that the feedback is large enough that the water height throughout the system drops so much that you can see it with the naked eye! It was really unexpected. Our study paves the way for experimental research into interactions between waves and the space-times that they cross. For example, this type of interaction will be crucial for studying the evaporation of black holes in the laboratory. “

Black hole research at the University of Nottingham recently received a £ 4.3million raise for a three-year project that aims to provide additional insight into the physics of the early universe and black holes .

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