First observation of Hawking radiation?

Hawking radiation

In 1974, Stephen Hawking predicted that black holes would emit radiation.

So-called Hawking radiation is produced when pairs of virtual particles pop into existence near the event horizon of a black hole (as they do all over the universe). Usually these pairs simply annihilate each other and disappear. But Hawking predicted that in some cases, one of the pair would sucked into hole while the other escaped. When that happened, the black hole would appear to emit radiation.

Nobody has actually observed Hawking radiation because it is too weak to see with our current gear. But perhaps scientists have been looking in the wrong place.

Iacopo Carusotto from the Universita di Trento in Italy and colleagues say they have spotted Hawking radiation in their lab on Earth.

Here’s what they did: the team created a mathematical model of an experiment with a Bose Einstein Condensate. The condensate flows along a waveguide with a particular speed, v. This sets up a kind of sonic horizon: any sound wave with speed less than v travelling back along the condensate can never cross this horizon.

Seems simple enough. But because BECs are no ordinary objects, it turns out that the physics of this situation is exactly analagous to what goes on at the event horizon of a black hole. So Hawking radiation could form at the horizon.

And sure enough, in their simulation, Carusotto and co observed the emission of a particular kind of sound wave called Bogoliubov phonons from the horizon, just as Hawking predicted.

Given that this is a numerical simualiton, the team’s claim that: “our observations can be considered as a first independent proof of the existence of Hawking radiation,” might be a little over-optimistic. But we get the idea.

Anybody got a BEC machine that could do this for real?

Ref: Numerical Observation of Hawking Radiation from Acoustic Black Holes in Atomic BECs

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