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- Hawking radiation in fluid flows

The emission of thermal radiation by black holes, discovered by Hawking, is now a broadly

accepted and major prediction of quantum

huge redshift that occurs near the horizon connects the low energy semiclassical physics to

some unknown high energy physics where the assumption of a free field on a smooth manifold can certainly be questioned. Hence, the Hawking process seems to depend on the ultraviolet

structure of gravity to be fully consistent.

In 1981, Unruh showed that sound waves in a moving fluid propagate exactly like the radiation

field in a curved geometry. When the velocity of the

fluid crosses the speed of sound, it behaves much like a horizon. This opens the possibility to mimic black hole geometries in

condensed matter systems.

To describe Hawking radiation in such fluids, one is forced to take into account the departure

from Lorentz invariance at short wavelengths. We establish under which conditions the Hawking

process is recovered in black hole flows, and what replaces the relativistic notion of horizon. In

white hole flows, despite the similarity of the scattering problem, a specific and new physical

phenomenon occurs. The large amplification of low frequencies through the Hawking effect

leads to the emission of a large, classical wave of zero frequency but nite wavelength. We

present the properties of this wave, and its birth, when it is triggered by quantum or thermal fluctuations.

Event Type:

Seminar

Collection/Series:

Scientific Area(s):

Speaker(s):

Event Date:

Jeudi, Octobre 9, 2014 - 14:30 to 16:00

Location:

Space Room

©2012 Institut Périmètre de Physique Théorique