191 research outputs found
Arrows of Time and the Anisotropic Properties of CMB
The relation between the thermodynamical and cosmological arrows of time is
usually viewed in the context of the initial conditions of the Universe. It is
a necessary but not sufficient condition for ensuring the thermodynamical
arrow. We point out that in the Friedmann-Robertson-Walker Universe with
negative curvature, k=-1, there is the second necessary ingredient. It is based
on the geodesic mixing - the dynamical instability of motion along null
geodesics in hyperbolic space. Kolmogorov (algorithmic) complexity as a
universal and experimentally measurable concept can be very useful in
description of this chaotic behavior using the data on Cosmic Microwave
Background radiation. The formulated {\it curvature anthropic principle} states
the negative curvature as a necessary condition for the time asymmetric
Universe with an observer.Comment: Revtex, to appear in the proceedings of the workshop THE CHAOTIC
UNIVERSE, Eds.V.G.Gurzadyan, R.Ruffini, World Sc
Free energy for non-equilibrium quasi-stationary states
We study a class of non-equilibrium quasi-stationary states for a Markov
system interacting with two different thermal baths. We show that the work done
under a slow, external change of parameters admits a potential, i.e., the free
energy. Three conditions are needed for the existence of free energy in this
non-equilibrium system: time-scale separation between variables of the system,
partial controllability (external fields couple only with the slow variable),
and an effective detailed balance. These conditions are facilitated in the
continuous limit for the slow variable. In contrast to its equilibrium
counterpart, the non-equilibrium free energy can increase with temperature. One
example of this is that entropy reduction by means of external fields (cooling)
can be easier (in the sense of the work cost) if it starts from a higher
temperature.Comment: 8 pages, 2 figure
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