When one thinks of psychology, very few would think to associate it with physics. Yet, the origins of Sigmund Freud’s elaborate theories in human dynamism and motivation stem from late 19th century progress in applying principles of energy conservation to thermodynamics, electromagnetism and nuclear physics. Bit of a stretch, you may think, but not so when one considers the very early considerations of Freud’s work, before his work on sexuality and childhood repression. This is the stuff of dynamic physiology and subsequent ‘psychic energy’ which Freud considered the means by which the human personality is transformed, and eventually upon which he would eventually found psychoanalytic theory.
(full thoughts at the link)