Lecture Notes in Cosmology

This book provides a comprehensive and pedagogically oriented introduction to modern cosmology, bridging the gap between introductory textbooks and the research literature. Developed from graduate courses and advanced schools, it combines physical insight with a solid mathematical foundation and is suitable for both self-study and classroom use. The second edition expands the historical account of cosmology, including translated excerpts from seminal papers, and offers updated discussions of cosmological distances, the Hubble tension, and thermal distributions in an expanding Universe. The opening chapters are structured to support a basic course in cosmology. Beginning with the observational foundations of the expanding Universe and its principal components, the book develops the theoretical framework from Newtonian arguments to the Friedmann–Lemaître–Robertson–Walker geometry, the Friedmann equations, and the ?CDM model. It then examines the microphysics of the early Universe, including kinetic theory, particle decoupling, relic abundances, nucleosynthesis, and recombination. Further chapters provide a self-contained treatment of cosmological perturbations, inflation, structure formation, and Cosmic Microwave Background anisotropies and polarization. Numerous explicit derivations, intermediate steps, and selected exercises guide readers through the subject and connect fundamental theory with modern cosmological observations.