1,098 research outputs found
Dynamics of spinning test particles in Kerr spacetime
We investigate the dynamics of relativistic spinning test particles in the spacetime of a rotating black hole using the Papapetrou equations. We use the method of Lyapunov exponents to determine whether the orbits exhibit sensitive dependence on initial conditions, a signature of chaos. In the case of maximally spinning equal-mass binaries (a limiting case that violates the test-particle approximation) we find unambiguous positive Lyapunov exponents that come in pairs ± lambda, a characteristic of Hamiltonian dynamical systems. We find no evidence for nonvanishing Lyapunov exponents for physically realistic spin parameters, which suggests that chaos may not manifest itself in the gravitational radiation of extreme mass-ratio binary black-hole inspirals (as detectable, for example, by LISA, the Laser Interferometer Space Antenna)
Out of equilibrium dynamics of classical and quantum complex systems
Equilibrium is a rather ideal situation, the exception rather than the rule
in Nature. Whenever the external or internal parameters of a physical system
are varied its subsequent relaxation to equilibrium may be either impossible or
take very long times. From the point of view of fundamental physics no generic
principle such as the ones of thermodynamics allows us to fully understand
their behaviour. The alternative is to treat each case separately. It is
illusionary to attempt to give, at least at this stage, a complete description
of all non-equilibrium situations. Still, one can try to identify and
characterise some concrete but still general features of a class of out of
equilibrium problems - yet to be identified - and search for a unified
description of these. In this report I briefly describe the behaviour and
theory of a set of non-equilibrium systems and I try to highlight common
features and some general laws that have emerged in recent years.Comment: 36 pages, to be published in Compte Rendus de l'Academie de Sciences,
T. Giamarchi e
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