Relativity and Cosmology: From First Principles to Interpretations provides a high-quality and highly relevant astrophysics grounding for senior undergraduate students. This comprehensive textbook emphasizes an illustrative, pedagogical approach and aims to strike a balance between the breadth and depth of the material presented, frequently tying new material – relativistic mechanics and gravity – to the classical mechanics and gravity with which readers are more familiar. It includes robust content and corresponding exercises, figures, and appendices on many exciting developments, including relativistic mechanics; Newtonian classical mechanics; relativistic spacetime; special relativity; general relativity; tensor calculus; cosmology; Einstein’s field equations; dark matter; dark energy; and black holes. This accessible edition delivers helpful and engaging additions to the role and importance of physics in cosmology and relativity. It is ideal for courses in physics, astrophysics, astronomy, and related subjects.