In quantum field theory, it is equivalent to one-loop Feynman diagrams. The idea is originally attributed to Lord Rayleigh, who used it to analyze the propagation of an optical disturbance in a nonuniform medium. In his version, he assumed that the wave number was proportional to the index of refraction. The rigorous mathematical theory of this app
In quantum field theory, it is equivalent to one-loop Feynman diagrams. The idea is originally attributed to Lord Rayleigh, who used it to analyze the propagation of an optical disturbance in a nonuniform medium. In his version, he assumed that the wave number was proportional to the index of refraction. The rigorous mathematical theory of this approximation for linear second-order differential equations was developed by Harold Jeffreys. For 10 points, name this approximation valid when the potential varies slowly compared to the wave function, a truncated asymptotic series named after three physicists.
In quantum field theory, it is equivalent to one-loop Feynman diagrams.
{W}entzel-{K}ramers-{B}rillouin-Jeffreys approximation [accept any permutation of the names or letters that contains the required/underlined information]