>>513685213 (OP)as someone who has been privileged enough to directly encounter and confront elemental evil incarnated in human form multiple times, i can say that it's something like any other kind of mystical experience- ineffable, impossible to prove to any other being. you have to experience it for yourself, and once you do, and have fully internalized the experience, you have crossed a threshold and can never go back. meeting evil, as it possesses a person who has made the decision to give themselves up to it and allow themselves to act as a conduit for it, changes you and forces you to make a choice about which side you're on.
even Nye's version of "science" has language which can explain aspects of this phenomenon- entropy being my favorite, but also polarity, and some aspects of chaos and complexity theories, inertia, magnetism. but i think good and evil, like other metaphysical realities, live more in the informational metadata attached to these scientific phenomena. good and evil are related to the valence or direction of the phenomenon.
you can see it in the eyes, i think. what i remember most clearly about the times i encountered people who were unquestionably possessed by either the spirit of elemental evil or Good were the eyes. this is reported by other people as well. people who are fully in the grips of evil, their eyes look dark, there is a blackness overlaid on top of them. similarly when i have seen people who are directly experiencing God or functioning as conduits for the Light- speaking for it, or allowing It to use their hands to help or heal others- I have seen their eyes as being full of Light.
if you're interested in scientific proofs for metaphysics, one of my favorite things to read about is the connection between genius- scientists at the very top of their field- and spontaneous inspiration. a huge number of scientific breakthroughs come from inspiration- ideas arriving fully formed, or in dreams, or visions.