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Hawking Radiation Claimed Created In a Lab
eldavojohn writes "In 1974, a young newcomer to the Royal Society named Stephen Hawking predicted that black holes emit Hawking Radiation. Researchers have been looking for it in space ever since. A new paper up for publication claims to have beaten searchers by observing it in a lab. Doing it wasn't easy. They say they brought light to a standstill by drastically increasing the refractive index of the material it was being fired at, creating a 'white hole.' This horizon, beyond which light cannot penetrate (event horizon), is the same between white and black holes, which caused the team to suspect they observed Hawking Radiation when light of a different uniform wavelength than the input laser was emitted. But, before you rejoice, the Tech Review article notes, 'Of course, the big question is whether the emitted light is generated by some other mechanism such as Cerenkov radiation, scattering or, in particular, fluorescence which is the hardest to rule out.'"
So when the virtual particle pair is created at the event horizon, one is trapped stationary beyond the horizon, and the other escapes (becoming real).
In this experiment obviously the event horizon doesn't persist indefinitely, so when the horizon collapses, do the 'trapped' photons escape? and hence is there a time delayed double emission of the hawking radiation? Would this provide a testable signature?
Any physicists know?
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By the way, even if this experiment and their conclusions hold water, it is not a proof of black hole evaporation or Hawking radiation. It would be more like a proof of concept.
In the experiment, they've created a pseudo-event-horizon from which light can't escape. It's only a light event horizon though. Shoot a bullet through their material and you will definately see it go through the event horizon without any problems.
The similarities to a real black hole is that photon pairs created on the pseudo-event-horizon should create radiation if Hawkings reasoning about real black holes is correct. So, it would show that Hawkings thought experiment had some merit but not that black holes necessarily radiate.
umm, is this what you're talking about?
weinersmith
Now, its creation is a quantum state transition which has a "magical" quality in the same way that, say, a photon escaping an atom's electron shell does. There is no extended energy transport process at all. The electron makes a quantum jump simultaneously with the photon field of the world gaining a new photon traveling away. Indeed, with visible light, the wavelength of the photon -- hundreds of nanometers -- can easily exceed the spatial scale of the atoms electron shell, usually a few nm. So, the photon kind of just "appears".
Not quite, i was referring to this. i couldn't look that up earlier because i was on a really bad connection that was dropping packets left right and center.
Why would the black hole diminish? Shouldn't the same amount of virtual particles and virtual anti-particles cross the event horizon?
- Raynet --> .
Although, the black holes that can currently evaporate due to this mechanism are (as I understand it) well below stellar mass. The amount of hawking radiation that larger black holes emit is below the amount of energy they receive from the cosmic microwave background, thus they cannot evaporate.
Leonard Susskind was the guy and the problem wasn't originally an "information" problem, but instead an entropy problem. The information questions came in after they sorted out the holographic principals of information representation along the surface area of the event horizon.
Sean M Carroll has a good book about what that means for time if you are interested...
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An electron's classical radius isn't zero, but more to the point, you can't use just classical physics at that scale.