Evidence for Hawking radiation - radiation released by black holes due to quantum effects - from a black-hole laser is reported in a paper published online in Nature Physics. This is the first observation of self-amplifying Hawking radiation, providing an exciting system for probing astrophysical black holes in the lab.

In 1974, Stephen Hawking showed that, due to quantum effects, black holes are not completely black but actually emit a type of radiation, now known as Hawking radiation. As the amount of radiation emitted would be very small, astrophysical observations may not be possible. Scientists have attempted to observe this radiation using sonic black holes made with fluids - from which sound, rather than light, cannot escape. However, observations of Hawking radiation in these systems have also proved elusive as the effect is extremely small.

Jeff Steinhauer demonstrates how Hawking radiation can be amplified by building a black-hole laser in the lab. Using a quantum fluid, Steinhauer pairs a black-hole horizon (the point of no return for sounds entering a black hole) with a white-hole horizon (the opposite; a point where sound can’t pass and is ejected). Such a system acts as a laser for sound waves, amplifying the emitted Hawking radiation to detectable levels.