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The physical implications of Itô and Stratonovich stochastic calculi are analysed in terms of the transformation of a Poisson multiplicative stochastic process into a Gaussian process. [ABSTRACT FROM AUTHOR]

In the absence of experimental facts to support the study of the origins of the Universe and black holes, reliance must be shifted to theory, especially thermodynamics. To superstring theories, dealing with the unification of the four known forces during the evolution of the early Universe, and black holes, the end product of gravitational collapse, have been attributed rather peculiar thermodynamic properties such as lack of concavity, with the consequence of negative heat capacities, non-extensivity. It has been proposed that superadditivity rather than concavity constitutes the essence of the second law. Here we refute such claims and show that concavity determines the natural evolution of thermodynamic processes. [ABSTRACT FROM AUTHOR]