Hawking Radiation in a Solid-State analog of a Black-Hole

The standard derivations of Hawking's radiation rely on the theory of a free quantized field on curved space-time, and describe the radiation as originating from vacuum fluctuations on scales exponentially smaller than the Planck scale. On such scales, free field theory is unlikely to be a valid description, and quantum-gravity effects should become important.  This is sometime know as the ``trans-Planckian puzzle".

The question is then, to what extent does the Hawking radiation dependent on the details of the short distance structure of quantum gravity?

In the absence of a full theory of quantum-gravity, guiding toy models, which are based on the well established physics, can be helpful. 

We have studied the trans-Planckian problem in the context of a solid-state inspired black-hole analog. We showed that an effective black-hole-like horizon occurs, for electromagnetic waves in matter, at a surface of singular electric and magnetic permeabilities. We then utilized the fact that in a physical dispersive medium, the effective curved geometry and the horizon disappear for short enough wave numbers.  Nevertheless, we have shown that Hawking radiation is still emitted if free field modes are initially in their ground state.

For the article on the "solid-state" black-hole see:

B. Reznik,  Origin of the Thermal Radiation in a Solid-State Analog of a Black-Hole,  Phys. Rev.  D 62, 44044 (2000). PRD.

and a colloquium  on  "Laboratory" Black-holes delivered on May 2000  at Tel Aviv.