This is the 2nd edition of a highly successful title on this fascinating and complex subject. Concentrating primarily on the theory behind the origin and the evolution of the universe, and where appropriate relating it to observation, the new features of the this addition include: An overall introduction to the book Two new chapters: Gravitational Lensing and Gravitational Waves Each part has a collection of exercises with solutions to numerical parts at the end of the book Contains a table of physical constants The addition of a consolidated bibilography