J. J. Sakurai Quote

... we see a number of sophisticated, yet uneducated, theoreticians who are conversant in the LSZ formalism of the Heisenberg field operators, but do not know why an excited atom radiates, or are ignorant of the quantum theoretic deerivation of Rayleigh's law that accounts for the blueness of the sky.

Modern Quantum Mechanics, Second Edition, Addison-Wesley, 2011.