Effective theories in classical and quantum mechanics
Ross H. McKenzie (noreply@blogger.com)
Working in quantum many-body theory, I slowly learned that many key concepts and techniques have predecessors and analogues in classical systems and one-body quantum systems. Examples include Green's functions, path integrals, cumulants, the linked cluster theorem, Hubbard-Stratonavich transformation (completing the square), mean-field theory, localisation due to disorder, and BBGKY hierarchy . Learning a full-blown quantum many-body version is easier if you first understand simpler analogues. T