February 2, 2006
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December 8, 2008
This is a short analysis of the changes in the concept of entropy as applied to physics of the present-day and Early Universe. Of special interest is a leading role of such a notion as deformation of a physical theory. The relation to a symmetry of the corresponding theory is noted. As this work is not a survey, the relevant author's works are mainly considered. This paper is to be published in special issue "Symmetry and Entropy" of journal SYMMETRY: Culture and Science
May 15, 1996
A pair of symmetric expressions for the second law of thermodynamics is put forward. The conservation and transfer of entropy is discussed and applied to problems like biology, culture and life itself. A new explanation is given to the cosmic expansion with the concept of diversity in this theory. The problem of contingency and necessity is also discussed.
January 3, 2005
Even after over 150 years of discussion, the interpretation of the second law of thermodynamics continues to be a source of confusion and controversy in physics. This confusion has been accentuated by recent challenges to the second law and by the difficulty in many cases of clarifying which formulation is threatened and how serious the implications of a successful challenge would be. To help bring clarity and consistency to the analysis of these challenges, the aim of this p...
February 18, 2019
The second law of thermodynamics is known to hold at small scales also when gravity plays a leading role, as in the case of black holes and self-gravitating radiation spheres. It has been suggested that it should as well at large scales. Here, by a purely kinematic analysis \textemdash based on the history of the Hubble factor and independent of any cosmological model \textemdash , we explore if this law is fulfilled in the case of homogeneous and isotropic universes regardle...
May 22, 2012
Temperature is an outsider in the laws of motion given by Newton and Einstein and this oversight is the source of the predictions of time-reversal-invariance made by these two great systems of motion. By taking into consideration Planck's law of blackbody radiation and the Doppler effect, in thinking about Maxwell's electromagnetic wave equation, I have shown that photons, in the environment through which any charged particle moves, act as a source of temperature-dependent fr...
September 26, 2017
We pointed out that the generalized second law of thermodynamics on a de Sitter universe whose energy density stochastically fluctuates due to quantum fluctuations is seemingly violated. We have shown that even in such a case, the generalized second law is unviolated by taking cosmological decoherence into account. It has been well known that the decoherence is necessary to give a reasonable reason why our universe looks classical. Our proposal can support the importance of d...
November 9, 2023
In this work, we address the thermodynamical evolution of the universe in the context of Loop Quantum Cosmology by considering the conditions for the existence of a time arrow in this approach. We find out that, for the existence of a time arrow in our universe, in terms of its obedience to the Generalized Second Law of Thermodynamics, the initial state of the cosmos must correspond to a negative entropy one.
September 9, 2010
The second law and the generalized second law of thermodynamics in cosmology in the framework of the modified Gauss-Bonnet theory of gravity are investigated. The conditions upon which these laws hold are derived and discussed.
March 5, 2021
In the standard model of cosmology, the Universe began its expansion with an anomalously low entropy, which then grew dramatically to much larger values consistent with the physical conditions at decoupling, roughly 380,000 years after the Big Bang. There does not appear to be a viable explanation for this `unnatural' history, other than via the generalized second law of thermodynamics (GSL), in which the entropy of the bulk, S_bulk, is combined with the entropy of the appare...
April 2, 2013
We discuss the evolution of the universe in the context of the second law of thermodynamics from its early stages to the far future. Cosmological observations suggest that most matter and radiation will be absorbed by the cosmological horizon. On the local scale, the matter that is not ejected from our supercluster will collapse to a supermassive black hole and then slowly evaporate. The history of the universe is that of an approach to the equilibrium state of the gravitatio...