A military term with origins in physics:

"Friction reflects possibilities, probabilities, and luck, all of which indicate conditions without logical reasoning. Due to the multitude of such factors it is difficult to gauge the resistance we face, and it is impossible to pair effects with causes.” ZOLTÁN JOBBÁGY

For CLAUSEWITZ friction was composed of seven elements: danger,physical exertion, imperfect information, structural resistance, chance events, physical and political limits, unpredictability of interactions, and disconnects between ends and means.

Globally, all aspects of military operations can be seen as an open series of possible and existent frictions. Understood in this way, friction is an essential part of deterrence, crisis management and peace operations. It is treated as a feedback loop, for example increasing or decreasing political friction militarily, military friction economically, or economic friction politically.