Quantum Mechanics (ongoing), Sturm-Lioville theory, Special Relativity (ongoing), Tensors (going towards General Relativity)
What finally clicked: Hermitian matrix, self-adjoint operators, quantum operators for energy and momentum, the Metric (for modeling spacetime curvature), etc.
What finally clicked: Hermitian matrix, self-adjoint operators, quantum operators for energy and momentum, the Metric (for modeling spacetime curvature), etc.