Reasoning in Physics “the most influential theories advocated by physicists lie beyond the reach of extant experimental methods, and are therefore extremely difficult to test empirically”

Feynman, R. P., Leighton, R. B., and Sands, M. (1965). The feynman lectures on physics; vol. i. American Journal of Physics, 33(9):750–752. “Physics, as a scientific discipline, is divided into different sub-disciplines”