Derivation of the Einstein Equivalence Principle in a Class of Condensed Matter Theories

Abstract

We consider a class of condensed matter theories in a Newtonian framework with a Lagrange formalism related in a natural way with the classical conservation laws \partial_t \rho + \partial_i (\rho v^i) = 0 \partial_t (\rho v^j) + \partial_i (\rho v^i v^j + p^{ij}) = 0 We show that for an algebraically defined ``effective Lorentz metric'' g_{\mu\nu} and ``effective matter fields'' \phi these theories are equivalent to material models of a metric theory of gravity with Lagrangian L = L_{GR} + L_{matter} - (8\pi G)^{-1}(\Upsilon g^{00}-\Xi (g^{11}+g^{22}+g^{33}))\sqrt{-g} which fulfils the Einstein equivalence principle and leads to the Einstein equations in the limit \Xi,\Upsilon\to 0.