Scientists have come closer to creating a laboratory-scale imitation of a black hole that emits Hawking radiation.
Researchers created the black hole analogue by trapping sound waves using an ultra cold fluid.
In 1974, physicist Stephen Hawking proposed that black holes are not totally black, calculating that a tiny amount of radiation would be able to escape the pull of a black hole.
Hawking radiation relies on a basic tenet of quantum theory - large fluctuations in energy can occur for brief moments of time.
This means the vacuum of space seethes with particles and their antimatter equivalents.
When pairs of particles emerge near the event horizon - the boundary between a black hole and the rest of the Universe - the particle-antiparticle pair separates, and the member of the pair closest to the event horizon falls into the black hole while the other one escapes.
However, researchers are yet to detect Hawking radiation being emitted from an astrophysical black hole.
Jeff Steinhauer, a physicist at the Technion-Israel Institute of Technology in Haifa, used a collection of rubidium atoms chilled to less than 1-billionth of a degree above absolute zero, 'nature.Com' reported.
The cold temperature ensures that the fluid, known as a Bose-Einstein condensate, provides a silent medium for the passage of sound waves that arise from quantum fluctuations.
Using laser light, Steinhauer manipulated the fluid to flow faster than the speed of sound. Like a swimmer battling a strong current, sound waves travelling against the direction of the fluid become 'trapped'.
The condensate thus becomes a stand-in for the gravitational event horizon.
Pairs of sound waves pop in and out of existence in a laboratory vacuum, mimicking particle-antiparticle pairs in the vacuum of space. Those that form astride this sonic event horizon become the equivalent of Hawking radiation.
To amplify these sound waves enough for his detectors to pick them up, Steinhauer established a second sonic event horizon inside the first, adjusting the fluid so that sound waves could not pass this second event horizon, and are bounced back.
As the soundwaves repeatedly strike the outer horizon, they create more pairs of soundwaves, amplifying the Hawking radiation to detectable levels.
