Lasers Simulate Black Hole Radiation
COLLEGE PARK, Md., Nov. 10, 2010 — A team of Italian scientists has fired a laser beam into a chunk of glass to create what they believe is an optical analogue of the Hawking radiation that many physicists expect is emitted by black holes. Although the laser experiment superficially bears little resemblance to ultradense black holes, the mathematical theories used to describe both are similar enough that confirmation of laser-induced Hawking radiation would bolster confidence that black holes also emit Hawking radiation.
Experimental layout produces a detectable analogue of Hawking radiation. The input laser pulse is focused into a sample of fused silica (FS) using an axicon or lens (F). An imaging lens (I) collects the photons emitted at 90 degrees and sends them to an imaging spectrometer coupled to a cooled CCD camera. (Image: F. Belgiorno, S.L. Cacciatori, M. Clerici, V. Gorini, G. Ortenzi, L. Rizzi, E. Rubino, V.G. Sala, D. Faccio)
When Stephen Hawking first predicted the radiation bearing his name in 1974, he hypothesized that photons could be spontaneously generated from the vacuum at the edge of a black hole. However, Hawking radiation emitted from a black hole would be so weak that many scientists believe it to be nearly impossible to detect.
Scientists have turned to lasers before in attempts to create Hawking radiation, but have had difficulty isolating Hawking radiation from other forms of light emitted during experiments. Franco Belgiorno and his team combined a tunable laser beam with a bulk glass target, which allowed them to limit the Hawking radiation to certain wavelengths of infrared light and to capture the apparent Hawking radiation with an infrared sensitive digital camera.
A paper describing the possible production of a laser-induced analogue of Hawking radiation appears in the Physical Review Letters, and is the subject of a Viewpoint article by John Dudley (CNRS, France) and Dmitry Skryabin (University of Bath, England) in Physics (physics.aps.org). Physics is a publication of the American Physical Society that provides expert written commentaries and highlights of papers appearing in the Society's journals
For more information, visit: www.aps.org
- digital camera
- A camera that converts a collected image into pixels that are black or white digital or shades of gray. The digital data may then be manipulated to enhance or otherwise modify the resulting viewed image.
- fused silica
- Glass consisting of almost pure silicon dioxide (SiO2). Also called vitreous silica. Frequently used in optical fibers and windows.
- The emission and/or propagation of energy through space or through a medium in the form of either waves or corpuscular emission.
- A kind of spectrograph in which some form of detector, other than a photographic film, is used to measure the distribution of radiation in a particular wavelength region.
- tunable laser
- Any form of laser; e.g., a dye laser, having an output that can be adjusted over a wide range of wavelengths. Normally the range is about 70 nm wide.
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