Why Symmetry? -- J-Pairing Interractions of Fermions in a Single-J Shell -- Supersymmetry in Nuclei -- The Relativistic Many Body Problem in Quantum Mechanics -- Gauge Invariance and the E1 Sum Rule in Nuclei -- The Heisenberg Group in Classical and Quantum Information Transmission -- Quantum Field Theory of Particle Mixing and Oscillations -- Two-Photon Interactions in Cavity QED -- Low-Dimens…