The quantum-mechanical "Schrödinger's cat" paradox according to the many-worlds interpretation. In this interpretation, every quantum event is a branch point; the cat is both alive and dead, even before the box is opened, but the "alive" and "dead" cats are in different branches of the multiverse, both of which are equally real, but which do not interact with each other.
The many-worlds interpretation implies that there are most likely an uncountable number of universes.[13] It is one of a number of multiverse hypotheses in physics and philosophy. MWI views time as a many-branched tree, wherein every possible quantum outcome is realized. This is intended to resolve the measurement problem and thus some paradoxes of quantum theory, such as Wigner's friend,[4]: 4–6 the EPR paradox[5]: 462 [1]: 118 and Schrödinger's cat,[6] since every possible outcome of a quantum event exists in its own universe.
^Brown, Harvey R.; Christopher G. Timpson (2016). "Bell on Bell's Theorem: The Changing Face of Nonlocality". In Mary Bell; Shan Gao (eds.). Quantum Nonlocality and Reality: 50 years of Bell's theorem. Cambridge University Press. pp. 91–123. arXiv:1501.03521. doi:10.1017/CBO9781316219393.008. ISBN9781316219393. S2CID118686956. On locality:"Amongst those who have taken Everett's approach to quantum theory at all seriously as an option, it is a commonplace that—given an Everettian interpretation—quantum theory is (dynamically) local-there is no action-at-a-distance" on determinism:"But zooming-out (in a God's-eye view) from a particular branch will be seen all the other branches, each with a different result of measurement being recorded and observed, all coexisting equally; and all underpinned by (supervenient on) the deterministically, unitarily, evolving universal wavefunction"
^Cecile M. DeWitt, John A. Wheeler (eds,) The Everett–Wheeler Interpretation of Quantum Mechanics, Battelle Rencontres: 1967 Lectures in Mathematics and Physics (1968).
^Bryce Seligman DeWitt, The Many-Universes Interpretation of Quantum Mechanics, Proceedings of the International School of Physics "Enrico Fermi" Course IL: Foundations of Quantum Mechanics, Academic Press (1972).
^H. Dieter Zeh, On the Interpretation of Measurement in Quantum Theory, Foundations of Physics, vol. 1, pp. 69–76, (1970).
^Wojciech Hubert Zurek, Decoherence and the transition from quantum to classical, Physics Today, vol. 44, issue 10, pp. 36–44, (1991).
^Wojciech Hubert Zurek, Decoherence, einselection, and the quantum origins of the classical, Reviews of Modern Physics, 75, pp. 715–775, (2003).