Sonic black holes produce “Hawking radiation,” may confirm famous theory

Enlarge / Simulated view of a black hole in front of the Large Magellanic Cloud. (credit: Wikimedia Commons/Alain r)

Israeli physicists think they have confirmed one of the late Stephen Hawking's most famous predictions by creating the sonic equivalent of a black hole out of an exotic superfluid of ultra-cold atoms. Jeff Steinhauer and colleagues at the Israel Institute of Technology (Technion) described these intriguing experimental results in a new paper in Nature.

The standard description of a black hole is an object with such a strong gravitational force that light can't even escape once it moves behind a point of no return known as the event horizon. But in the 1970s, Hawking demonstrated that-theoretically, at least-black holes should emit tiny amounts of radiation and gradually evaporate over time.

Blame the intricacies of quantum mechanics for this Hawking radiation. From a quantum perspective, the vacuum of space continually produces pairs of virtual particles (matter and antimatter) that pop into existence and just as quickly annihilate away. Hawking proposed that a virtual particle pair, if it popped up at the event horizon of a black hole, might have different fates: one might fall in, but the other could escape, making it seem as if the black hole were emitting radiation. The black hole would lose a bit of its mass in the process. The bigger the black hole, the longer it takes to evaporate. (Mini-black holes the size of a subatomic particle would wink out of existence almost instantaneously.)

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