2025/04/01 by Tanmoy Paul, Paul, Tanmoy · 4 citations
Physics and Astronomy · #Advanced Mathematical Theories and Applications #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #General Relativity and Quantum Cosmology (gr-qc)
paper · pdf · doi:10.48550/arxiv.2504.00422
openalex publication_date 2025/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The purpose of the present work is two folded: (1) we propose a new mechanism for the origin of bulk viscosity in cosmological context, and then, (2) we address the thermodynamic implications of viscous cosmology based on the thermodynamics of apparent horizon. In particular, we show that the velocity gradient of the comoving expansion of the universe (along the distance measured from a comoving observer) in turn leads to a viscous like pressure of the fluid inside the apparent horizon. This points the importance of the bulk viscosity of fluid during the cosmological evolution of the universe, as the comoving expansion itself generates the viscosity. Therefore the thermodynamic interpretations of viscous cosmology becomes important from its own right. In this regard, it turns out that the cosmological evolution of the universe with a bulk viscosity naturally satisfies the first and the second laws of thermodynamics of the apparent horizon, without imposing any exotic condition and for a general form of the coefficient of viscosity. This in turn affirms the thermodynamic correspondence of viscous cosmology.