Lecture

Thermal History and Cosmic Microwave Background

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Description

This lecture covers the thermal history of the universe, focusing on the equilibrium state and the temperature of the Cosmic Microwave Background (CMB). The instructor discusses the Boltzmann equation and its relevance to understanding the behavior of particles in thermal equilibrium. The lecture emphasizes the significance of the CMB in cosmology, detailing how it provides insights into the early universe and the evolution of matter and radiation. The instructor explains the concept of luminosity distance and its connection to standard candles, which are essential for measuring astronomical distances. The relationship between the CMB temperature and the expansion of the universe is also explored, highlighting the implications for baryogenesis and the formation of structures in the cosmos. Throughout the lecture, the instructor presents mathematical formulations and physical principles that underpin these concepts, providing a comprehensive overview of the thermal dynamics that shaped the universe as we know it today.

Official source

Ontological neighbourhood

Astronomy

Astrophysics: Physical cosmology

Physics

Thermodynamics: Statistical mechanics

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The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, with an uncertainty of around 21 million years at the 68% confidence level. For the purposes of this summary, it is convenient to divide the chronology of the universe since it originated, into five parts.

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The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. According to this theory, space and time emerged together 13.787billion years ago, and the universe has been expanding ever since the Big Bang. While the spatial size of the entire universe is unknown, it is possible to measure the size of the observable universe, which is approximately 93 billion light-years in diameter at the present day.

Ultimate fate of the universe

The ultimate fate of the universe is a topic in physical cosmology, whose theoretical restrictions allow possible scenarios for the evolution and ultimate fate of the universe to be described and evaluated. Based on available observational evidence, deciding the fate and evolution of the universe has become a valid cosmological question, being beyond the mostly untestable constraints of mythological or theological beliefs.

Physical cosmology

Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood.

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