scholarly journals On a reverse isoperimetric inequality for relative outer parallel bodies

2020 ◽  
Vol 148 (11) ◽  
pp. 4923-4931
Author(s):  
Eugenia Saorín Gómez ◽  
Jesús Yepes Nicolás
Keyword(s):  
Isoperimetric Inequality ◽  
Reverse Isoperimetric Inequality

scholarly journals Instability of super-entropic black holes in extended thermodynamics

2020 ◽  
Vol 35 (13) ◽  
pp. 2050098 ◽  
Author(s):  
Clifford V. Johnson
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Specific Heat ◽  
Isoperimetric Inequality ◽  
Large Family ◽  
Constant Volume ◽  
Extended Thermodynamics ◽  
Charged Black Hole ◽  
Reverse Isoperimetric Inequality ◽  
Gravitational Thermodynamics

The charged black hole of Bañados, Teitelbiom and Zanelli is studied in extended gravitational thermodynamics where there is a dynamical pressure and volume. It is a simple example of a super-entropic black hole, violating the reverse isoperimetric inequality. It is proven that this property implies that its specific heat at constant volume is negative, signaling a new kind of fundamental instability for black holes. It is conjectured that this instability is present for other super-entropic black holes, and this is demonstrated numerically for a large family of known solutions.

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