Violation of the First Law of Thermodynamics in <i>f</i> ( <i>R</i> , <i>T</i> ) Gravity

In this Letter, we derived the first law of thermodynamics using the method proposed by Wald. Treating the entropy as Noether charge and comparing with the usual first law of thermodynamics, we obtained the expression of entropy explicitly which contains infinitely many non-local terms (i.e. the integral terms). We have proved, in general, that the first law of black bole thermodynamics is violated for $f(R,T)$ gravity. But there might exist some special cases in which the first law for $f(R,T)$ gravity is recovered.

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