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Entropy Production in the Expanding Universe
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1  Department of Physics, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran


The space-time is basically curved and dynamical. Thus our knowledge of universe must be extend to a dynamical curved space-time to understand the nature of the universe. The field theory in the curved space-time has shown that the evolution of space-time involving the field in the curved space-time leads to the particle creation. In other side, by employing thermodynamics to cosmology, we can learn about the source of current entropy content associated with the universe. From the quantum thermodynamics, one has been manifested that the inner friction stemming from the quantum fluctuations of field can produce the entropy. Using this approach, the particle creation due to the expansion of space-time beginning from the vacuum is shown as an entropic increase. considering an asymptotically flat Robertson-Walker space-time, the particle creation entropy is evaluated. Each special scale factor can be used to characterize the cosmic parameters. Thus, the dependence of particle creation entropy on the field parameters and the cosmic parameters allows us to recover information from the underling structure of the space-time. Also, by adding a difference function to this particle creation entropy, the well-known entanglement measure can obtained to investigate the entanglement of created particles.  The quantum fluctuations of vacuum stemming from dynamical space–time can be interpreted as the entanglement work. In fact, the entanglement entropy, measuring the mixedness of the primary state, is affected from the creation and the correlation of the particle.

Keywords: Entropy Production-Quantum Thermodynamics-Entanglement