Physics from Symmetry This is a textbook that derives the fundamental theories of physics from symmetry. It starts by introducing in a completely self contained way all mathematical tools needed to use symmetry ideas in physics. Thereafter these tools are put into action and by using symmetry constraints the fundamental equations of Quantum Mechanics Quantum Field Theory Electromagnetism and Classical Mechanics are derived. As a result the reader is able to understand the basic assumptions behind and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations