This book presents the two foundational pillars of modern physics, quantum mechanics and general relativity, in a coherent form aimed primarily at upper-level undergraduate students. It provides a unified picture of the underlying field of mathematical physics and the fruitful interactions between different methods and applications. To help students navigate both topics, the book takes a systematic, pedagogical and uniform approach to the underlying theories and applications. This includes detailed discussions of applications, such as in atomic and particle physics, measurements of space and time, black holes and cosmology. Fundamental Physics: A Guide to Relativity and Quantum Theory is essential for upper-level undergraduate students looking to develop a cohesive understanding of the ways in which quantum mechanics and general relativity are central not only to the challenges and approaches to quantum theories of gravity but also to gravitational implications on sensitive quantum effects. Worked examples and homework problems are available throughout. Key Features:This class-tested textbook combines two fundamental topics in modern physics: quantum mechanics and general relativityDetailed conceptual discussions of physics insights are combined with careful mathematical constructionsWorked examples are available throughoutChapter-end homework problems are also included