Desktop Black Holes

Description

Black holes are among the most fascinating predictions of Einstein's theory of gravity. Their main characteristic is a "surface of no return" or "event horizon", from behind which even light cannot escape to an outside observer. When combined with quantum mechanics, the event horizon leads to one of the deepest puzzles in theoretical physics today, known as the "information paradox". But even though black holes are known to exist in the universe, it is clearly not easy to do experiments with them.

However, various scientists have argued that many aspects of black holes have an analogue in ordinary fluids and other relatively simple systems, such as Bose-Einstein condensates! In these systems, sound waves or electromagnetic waves get trapped in certain regions of space, much like the way in which light gets trapped behind the black hole event horizon. Many aspects of black hole physics, for instance Hawking radiation and quantum black hole evaporation, can thus be studied directly, in a much simpler setup than that of gravitational physics.

Although doing experiments with such "desktop black holes" is still quite a challenge, several groups around the globe have in recent years made substantial progress with them.

In this project, you will get to learn how these "laboratory black holes" resemble real gravitational black holes, how they differ from them, and study several aspects of their fascinating physics.

Prerequisites

You must have taken General Relativity last year, or take it this year as a co-requisite for this project. You do not absolutely need Quantum Mechanics III, but it will certainly make your life a lot easier if you have some quantum mechanics under your belt too.

Resources and references

There is by now quite a substantial literature on "black holes in the lab", from the purely experimental side (which will concern us less) to numerical simulations and purely theoretical analysis. Some starting points are given below.

• Experimental black-hole evaporation?, the original paper in which William Unruh first worked out the theoretical possibility of seeing the analogue of black hole evaporation in fluid flow.
• Acoustic black holes: horizons, ergospheres, and Hawking radiation, a good introduction to the theoretical/mathematical analysis of desktop black holes.
• Hawking radiation mimicked in the lab, a recent Nature article about an experiment by Jeff Steinhauer at Technion who claims to have observed the analogue of Hawking radiation in a Bose-Einstein condensate.
• Simulated black hole yields Hawking radiation, reporting on a numerical simulation of black holes in Bose-Einstein condensates by the group of Iacopo Carusotto.
• Fibre-optical analogue of the event horizon, on the experiments with horizons in optical fibres, done by the group at St. Andrews.