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Entropic Law of Force, Emergent Gravity and the Uncertainty Principle
The entropic formulation of the inertia and the gravity relies on quantum,
geometrical and informational arguments. The fact that the results are
completly classical is missleading. In this paper we argue that the entropic
formulation provides new insights into the quantum nature of the inertia and
the gravity. We use the entropic postulate to determine the quantum uncertainty
in the law of inertia and in the law of gravity in the Newtonian Mechanics, the
Special Relativity and in the General Relativity. These results are obtained by
considering the most general quantum property of the matter represented by the
Uncertainty Principle and by postulating an expression for the uncertainty of
the entropy such that: i) it is the simplest quantum generalization of the
postulate of the variation of the entropy and ii) it reduces to the variation
of the entropy in the absence of the uncertainty.Comment: 10 pages. Important discussion of the special relativistic case and
the newtonian limit of the general relativistic case added. The paper has
been reformatted. The authorship listing corrected. (It has been published by
mistake out of order in the first version. We have been adhering to the
Hardy-Littlewood Rule over the years.) Typos corrected. Four references adde
DSMC evaluation of the Navier-Stokes shear viscosity of a granular fluid
A method based on the simple shear flow modified by the introduction of a
deterministic non-conservative force and a stochastic process is proposed to
measure the Navier-Stokes shear viscosity in a granular fluid described by the
Enskog equation. The method is implemented in DSMC simulations for a wide range
of values of dissipation and density. It is observed that, after a certain
transient period, the system reaches a hydrodynamic stage which tends to the
Navier-Stokes regime for long times. The results are compared with theoretical
predictions obtained from the Chapman-Enskog method in the leading Sonine
approximation, showing quite a good agreement, even for strong dissipation.Comment: 6 pages, 4 figures; to appear in Rarefied Gas Dynamics: 24th
International Symposium (AIP Conference Proceedings
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