Chaos, thermodynamics and quantum mechanics: an application to celestial dynamics

We address the issue of the quantum-classical correspondence in chaotic sys tems using, as recently done by Zurek [Phys. Scr. T 76 (1998) 186], the sol ar system as a whole as a case study: this author shows that the classicali ty of the planetary motion is ensured by the environment-induced decoherenc e. We show that equivalent results are provided by the theories of spontane ous fluctuations and that these latter theories, in some cases, result in a still faster process of decoherence. We show that, as an additional benefi t, the assumption of spontaneous fluctuation makes it possible to genuinely derive thermodynamics from mechanics, namely, without implicitly assuming thermodynamics. (C) 1998 Published by Elsevier Science B.V.