The simulation hypothesis proposes that all of our existence is a simulated reality, such as a computer simulation.

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 human 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. The hypothesis popularized by Bostrom is very disputed, with, for example, theoretical physicist Sabine Hossenfelder, who called it pseudoscience and cosmologist George F. R. Ellis, who stated that "[the hypothesis] is totally impracticable from a technical viewpoint" and that "protagonists seem to have confused science fiction with science. Late-night pub discussion is not a viable theory."