 As a matter of historical fact, it is unclear whether this idea of many co-existing worlds accords with Everett’s own view: Everett stated that the wave function serves the purpose of providing us with a set of factual and counterfactual descriptions of the world we live in, and this suggests that he rather saw his relative-state interpretation as a theory about one single world. This would make Everett’s interpretation a modal interpretation (see for extensive discussion Dieks 2021).