13,110 research outputs found
Information Entropy in Cosmology
The effective evolution of an inhomogeneous cosmological model may be
described in terms of spatially averaged variables. We point out that in this
context, quite naturally, a measure arises which is identical to a fluid model
of the `Kullback-Leibler Relative Information Entropy', expressing the
distinguishability of the local inhomogeneous mass density field from its
spatial average on arbitrary compact domains. We discuss the time-evolution of
`effective information' and explore some implications. We conjecture that the
information content of the Universe -- measured by Relative Information Entropy
of a cosmological model containing dust matter -- is increasing.Comment: LateX, PRLstyle, 4 pages; to appear in PR
Information entropy in fragmenting systems
The possibility of facing critical phenomena in nuclear fragmentation is a
topic of great interest. Different observables have been proposed to identify
such a behavior, in particular, some related to the use of information entropy
as a possible signal of critical behavior. In this work we critically examine
some of the most widespread used ones comparing its performance in bond
percolation and in the analysis of fragmenting Lennard Jones Drops.Comment: 3 pages, 3 figure
Information entropy and dark energy evolution
The information entropy is here investigated in the context of early and late
cosmology under the hypothesis that distinct phases of universe evolution are
entangled between them. The approach is based on the \emph{entangled state
ansatz}, representing a coarse-grained definition of primordial \emph{dark
temperature} associated to an \emph{effective entangled energy density}. The
dark temperature definition comes from assuming either Von Neumann or linear
entropy as sources of cosmological thermodynamics. We interpret the involved
information entropies by means of probabilities of forming structures during
cosmic evolution. Following this recipe, we propose that quantum entropy is
simply associated to the thermodynamical entropy and we investigate the
consequences of our approach using the adiabatic sound speed. As byproducts, we
analyze two phases of universe evolution: the late and early stages. To do so,
we first recover that dark energy reduces to a pure cosmological constant, as
zero-order entanglement contribution, and second that inflation is
well-described by means of an effective potential. In both cases, we infer
numerical limits which are compatible with current observations.Comment: 12 pages, 1 figur
Information entropy and nucleon correlations in nuclei
The information entropies in coordinate and momentum spaces and their sum
(, , ) are evaluated for many nuclei using "experimental"
densities or/and momentum distributions. The results are compared with the
harmonic oscillator model and with the short-range correlated distributions. It
is found that depends strongly on and does not depend very much
on the model. The behaviour of is opposite. The various cases we consider
can be classified according to either the quantity of the experimental data we
use or by the values of , i.e., the increase of the quality of the density
and of the momentum distributions leads to an increase of the values of . In
all cases, apart from the linear relation , the linear relation
also holds. V is the mean volume of the nucleus. If is
considered as an ensemble entropy, a relation between or and the
ensemble volume can be found. Finally, comparing different electron scattering
experiments for the same nucleus, it is found that the larger the momentum
transfer ranges, the larger the information entropy is. It is concluded that
could be used to compare different experiments for the same nucleus and to
choose the most reliable one.Comment: 14 pages, 4 figures, 2 table
The information entropy of quantum mechanical states
It is well known that a Shannon based definition of information entropy leads
in the classical case to the Boltzmann entropy. It is tempting to regard the
Von Neumann entropy as the corresponding quantum mechanical definition. But the
latter is problematic from quantum information point of view. Consequently we
introduce a new definition of entropy that reflects the inherent uncertainty of
quantum mechanical states. We derive for it an explicit expression, and discuss
some of its general properties. We distinguish between the minimum uncertainty
entropy of pure states, and the excess statistical entropy of mixtures.Comment: 7 pages, 1 figur
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