عنوان مجله
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INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS
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چکیده
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Observational data (Supernovae type I a data) indicate that the rate of the universe
expansion is increasing, which means that, in the framework of General Relativity, the
current phase of the expansion is due to an unknown source of energy. Therefore, the nature
of dominated fluid in cosmos, as the source of energy, is mysterious. Here, by considering
this property of current accelerating phase along with the concept of thermodynamics equilibrium
we try to find possible values for the state parameter (ω) of the dominated fluid in
a (n + 1)-dimensional Friedmann-Robertson-Walker universe. Our results are compatible
with previous work for Gauss-Bonnet gravity and point to a universe which is so close to
its thermodynamic equilibrium state. By the evolution of the cosmos, the baryonic content
of the cosmos is participating in longer range interactions, including gravity and electromagnetism,
and structure formation is begun which leads to an increase in the complexity
content of the universe. Therefore, a true model for the cosmos should show this rise of
complexity and information. In order to achieve this goal, we introduce a simple model
including free particles in an expanding box and try to count the number of the states of
energy. This configuration shows that the entropy of these number of states as the measure
for complexity is increased when dominated fluid satisfies special condition (ω ≥ −1)
which is compatible with the results of the Supernovae type I a data and the thermodynamic
equilibrium conditions. Finally, We see that the rate of increase in the complexity content
of the universe increases in the ω→−1 limit.
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