Dolan, Brian P.
Pressure and volume in the first law of black
Classical and Quantum Gravity, 28.
The mass of a black hole is interpreted, in terms of thermodynamic potentials,
as being the enthalpy, with the pressure given by the cosmological constant.
The volume is then defined as being the Legendre transform of the pressure
and the resulting relation between volume and pressure is explored in the case
of positive pressure. A virial expansion is developed and a van der Waals
like critical point determined. The first law of black hole thermodynamics
includes a PdV term which modifies the maximal efficiency of a Penrose
process. It is shown that, in four dimensional space-time with a negative
cosmological constant, an extremal charged rotating black hole can have an
efficiency of up to 75%, while for an electrically neutral rotating back hole
this figure is reduced to 52%, compared to the corresponding values of 50%
and 29% respectively when the cosmological constant is zero.
||General Relativity and Quantum Cosmology; High Energy Physics;
||Science & Engineering > Mathematical Physics
Dr. Brian Dolan
||27 Jan 2012 10:03
|Journal or Publication Title:
||Classical and Quantum Gravity
||Institute of Physics
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