Thermodynamics of the Primordial Universe

TL;DR

This review explores the thermodynamics of the early universe, integrating gravity, particle physics, and thermodynamics to understand its evolution and the laws governing its constituents during the primordial epoch.

Contribution

It provides a comprehensive analysis of thermodynamics within the Standard Cosmological Model, including equilibrium and out-of-equilibrium phenomena in the early universe.

Findings

Insights into the thermal history of the universe

Analysis of equilibrium thermodynamics in expansion

Study of out-of-equilibrium processes shaping early evolution

Abstract

This review delves into the pivotal primordial stage of the universe, a period that holds the key to understanding its current state. To fully grasp this epoch, it is essential to consider three fundamental domains of physics: gravity, particle physics, and thermodynamics. The thermal history of the universe recreates the extreme high-energy conditions that are critical for exploring the unification of the fundamental forces, making it a natural laboratory for high-energy physics. This thermal history also offers valuable insights into how the laws of thermodynamics have governed the evolution of the universe's constituents, shaping them into the forms we observe today. Focusing on the Standard Cosmological Model (SCM) and the Standard Model of Particles (SM), this paper provides an in-depth analysis of thermodynamics in the primordial universe. The structure of the study includes an introduction to the SCM and its strong ties to thermodynamic principles. It then explores equilibrium thermodynamics in the context of the expanding universe, followed by a detailed analysis of out-of-equilibrium phenomena that were pivotal in shaping key events during the early stages of the universe's evolution.