Nonequilibrium Thermodynamics of Spacetime

Christopher Eling, Raf Guedens, Ted Jacobson
2006 Physical Review Letters  
It has previously been shown that the Einstein equation can be derived from the requirement that the Clausius relation dS = dQ/T hold for all local acceleration horizons through each spacetime point, where dS is one quarter the horizon area change in Planck units, and dQ and T are the energy flux across the horizon and Unruh temperature seen by an accelerating observer just inside the horizon. Here we show that a curvature correction to the entropy that is polynomial in the Ricci scalar
more » ... icci scalar requires a non-equilibrium treatment. The corresponding field equation is derived from the entropy balance relation dS =dQ/T+dS_i, where dS_i is a bulk viscosity entropy production term that we determine by imposing energy-momentum conservation. Entropy production can also be included in pure Einstein theory by allowing for shear viscosity of the horizon.
doi:10.1103/physrevlett.96.121301 pmid:16605892 fatcat:h6y54vfningyrfmqdr2eckfqna