In philosophy of mind, epiphenomenalism is a form of dualism (the view that the body and the soul are made of two different substances), where it it said that the physical fully dictates the constitution and behavior of the mental, but not vice versa (the other way around).
One rough analogy would be that between fire and smoke. The configuration of the smoke is dictated by the configuration of the fire, but the configuration of fire is not dictated by the configuration of smoke. However, this doesn't hold up since the fire will be affected by the smoke (as long as the fire in question is within the smokes light cone), although to a very (very, very) small degree. So, this can't be a case of genuine epiphenomenalism.
My question is: Are there, or could there theoretically be, any confirmed cases of epiphenomenalism (not necessarily having anything to do with philosophy of mind)?
Here, a tentative (more or less), formalized definition of epiphenomenalism would be:
Epiphenomenalism := when the state and/or postion of an object a, at any point in time at or after time t (at which b gets affected by a), is different from the state and/or position it would have if b wasn't affected by a's action
To me, the statement that there could be confirmed cases of epiphenomenalism sounds like a contradiction. If x affects y (but not the other way around), an observer confirming the changes of y would have to be isolated from x (as in not part of the universe since everything affects everything to a very small degree), otherwise there would be a causal chain from y to x.
One example I can think of is that of quantum entanglement. Let's say that particle a and b are entangled and that we keep particle a on earth and transport particle b to the sun. If I were to measure particle a, particle b would instantaneously be affected, right? (Sorry if my knowledge in physics lets me down here. I don't know if it is correct to say that particle a affects particle b when a measurement is made on particle a, this question would suggest it isn't but in that case we can redefine quantum entanglement, so that it works in the way we want it to, and think of it as a made up concept that still is relevant to the question of the theoretical possibility of ever detecting epiphenomenalism). Also, particle b wouldn't affect particle a back. This would then seem like a case of epiphenomenalism. However, the epiphenomenalism would only be temporally true since after 8 minutes (the time it takes to travel between the sun and earth with the speed of light), particle a would lie within the light cone of particle b in its new, measured state, right?