Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: JimBob on 07/03/2008 01:09:51
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From "Science" - Amer. Assoc. Advancement of Science weekly Magazine Notifications email
Test of Hawking's Prediction on the Horizon With Mock 'White Hole'
by Adrian Cho
Using an optical fiber and laser light, physicists have simulated a "white hole"--essentially a black hole working in reverse--as they report on page 1367 of this week's issue of Science. The model might soon mimic the "Hawking radiation" predicted to emanate from black holes.
Seeing Over the Optical Event Horizon
The event horizon of a gravitational black hole represents a point of no return--particles inside this boundary, including photons, cannot escape. However, the direct observation of the event horizon and the possibility of verifying the proposed theoretical properties appear remote. Looking to lab-based analogies that may describe the underlying physics, Philbin et al. (p.1367; see the news story by Cho) report to have found a connection between light propagation in optical fibers and black hole physics. They report on the observation of an optical event horizon and probe some of the expected properties, such as frequency shifting of probe light. The authors also propose a scenario for observing Hawking radiation.
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Have you got a link to the full article, or is that all there is?
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In order to read the full article you must be a member of the American Association for the Advancement of Science. I am not. So I go to the library to read these articles if the arouse my interest. I'll copy it the next time I am there and then scan and convert to document format - perhaps PDF and send it to you.
The magazine's name is "Science"
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OK. Thanks, Jim. It sounds like an interesting read.
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From http://www.newscientist.com/channel/fundamentals/quantum-world/mg19726434.800-black-hole-event-horizon-created-in-the-lab.html (http://www.newscientist.com/channel/fundamentals/quantum-world/mg19726434.800-black-hole-event-horizon-created-in-the-lab.html)
IMAGINE being able to peek inside a black hole and even perform experiments there. It may not be as far-fetched as it sounds, thanks to a team which claims to have simulated a black hole's event horizon in the lab.
Ulf Leonhardt at the University of St Andrews, UK, and his colleagues accomplished the feat by firing lasers down an optical fibre, exploiting the fact that different wavelengths of light move at different speeds within an optical fibre.
They first shot a relatively slow-moving laser pulse through the fibre, and then sent a faster "probe wave" chasing after it. The first pulse distorts the optical properties of the fibre simply by travelling through it. This distortion forces the speedy probe wave to slow down dramatically when it catches up with the slower pulse and tries to move through it. In fact, the probe wave becomes trapped and can never overtake the pulse's leading edge, which effectively becomes a black hole event horizon, beyond which light cannot escape.
This "laser black hole" could allow physicists to examine what happens to light on both sides of a event horizon - "a feat that is utterly impossible in astrophysics", the authors note in their paper (www.arxiv.org/abs/0711.4796).
Cosmologists have already worked out exactly how light should change frequency as it approaches an event horizon - from the outside or the inside of a black hole - and sure enough, the team observed exactly these shifts in their experiment.
It should also be possible to use the artificial event horizon to help test whether anything can escape from a black hole. In the 1970s, Stephen Hawking predicted that hot black holes could radiate particles, dubbed Hawking radiation, but it's tough to check this using telescopes, because they'd be swamped by noise. The team calculates that their laser black hole shares this property, and that it will "radiate" photons if it heats up to about 1000 °C.
Ray Rivers at Imperial College London is impressed by the work's potential to test astrophysical phenomena: "They've done some clever stuff to give us a chance of seeing Hawking radiation for the first time." Leonhardt presented the results at the Cosmology Meets Condensed Matter meeting in London last month.
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Do I need to send you the paper or does this assuage you curiosity?
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Consider my curiosity assuaged [:)]