The basic behavioral hypothesis that an organism will choose a course of action that appears to require the smallest amount of effort or expenditure of energy. Also called law of least action.

The simulation hypothesis or simulation theory is the proposal that all of reality, including the Earth and the rest of the universe, could in fact be an artificial simulation, such as a computer simulation. Some versions rely on the development of a simulated reality, a proposed technology that would be able to convince its inhabitants that the simulation was "real". The simulation hypothesis bears a close resemblance to various other skeptical scenarios from throughout the history of philosophy. The hypothesis was popularized in its current form by Nick Bostrom. The suggestion that such a hypothesis is compatible with all of our perceptual experiences is thought to have significant epistemological consequences in the form of philosophical skepticism. Versions of the hypothesis have also been featured in science fiction, appearing as a central plot device in many stories and films.