Editing Many-worlds interpretation (section)

=== Rejection ===

Some scientists consider some aspects of MWI to be [[unfalsifiable]] and hence unscientific because the multiple parallel universes are non-communicating, in the sense that no information can be passed between them.<ref name=Bunge>{{cite book |author1=Bunge, M. |year=2012 |title=Evaluating Philosophies |chapter=Parallel Universes? Digital Physics? |series=Boston Studies in the Philosophy and History of Science |volume=295 |pages=152–153 |publisher=Springer |location=New York |doi=10.1007/978-94-007-4408-0|isbn=978-94-007-4407-3 }}</ref><ref name=Ellis>{{cite journal |author1=Ellis, G. |author2=Silk, J. |year=2014 |title=Scientific method: Defend the integrity of physics |journal=Nature |volume=516 |issue=7531 |pages= 321–323 |doi=10.1038/516321a |doi-access=free |bibcode=2014Natur.516..321E |pmid=25519115 }}</ref>

[[Victor J. Stenger]] remarked that [[Murray Gell-Mann]]'s published work explicitly rejects the existence of simultaneous parallel universes.<ref name="stenger1995">{{cite book |last=Stenger |first=V. J. |title=The Unconscious Quantum: Metaphysics in Modern Physics and Cosmology |publisher=Prometheus Books |year=1995 |isbn=978-1-57392-022-3 |lccn=lc95032599}}</ref> Collaborating with [[James Hartle]], Gell-Mann worked toward the development of a more "palatable" ''post-Everett quantum mechanics''. Stenger thought it fair to say that most physicists find MWI too extreme, though it "has merit in finding a place for the observer inside the system being analyzed and doing away with the troublesome notion of wave function collapse".{{efn|"Gell-Mann and Hartle, along with a score of others, have been working to develop a more palatable interpretation of quantum mechanics that is free of the problems that plague all the interpretations we have considered so far. This new interpretation is called, in its various incarnations, '''post-Everett quantum mechanics''', alternate histories, consistent histories, or decoherent histories. I will not be overly concerned with the detailed differences between these characterizations and will use the terms more or less interchangeably."<ref name="stenger1995"/>{{rp|176}}}}

[[Roger Penrose]] argues that the idea is flawed because it is based on an oversimplified version of quantum mechanics that does not account for gravity. In his view, applying conventional quantum mechanics to the universe implies the MWI, but the lack of a successful theory of [[quantum gravity]] negates the claimed universality of conventional quantum mechanics.<ref name="penrose">{{cite web|last=Penrose |first=Roger |author-link=Roger Penrose |title=Roger Penrose Looks Beyond the Classic-Quantum Dichotomy |publisher=Sciencewatch |date=August 1991 |url=http://www.sciencewatch.com/interviews/roger_penrose2.htm |access-date=2007-10-21 |url-status=dead |archive-url=https://web.archive.org/web/20071023063403/http://www.sciencewatch.com/interviews/roger_penrose2.htm |archive-date=2007-10-23 }}</ref> According to Penrose, "the rules must change when gravity is involved". He further asserts that gravity helps anchor reality and "blurry" events have only one allowable outcome: "electrons, atoms, molecules, etc., are so minute that they require almost no amount of energy to maintain their gravity, and therefore their overlapping states. They can stay in that state forever, as described in standard quantum theory". On the other hand, "in the case of large objects, the duplicate states disappear in an instant due to the fact that these objects create a large gravitational field".<ref name="ball">{{Cite web|first=Philip |last=Ball |author-link=Philip Ball |date=2015-02-17 |access-date=2021-09-23 |title=Too many worlds|url=https://aeon.co/essays/is-the-many-worlds-hypothesis-just-a-fantasy|website=[[Aeon.co]]}}</ref><ref>{{Cite web|title=If an Electron Can Be in Two Places at Once, Why Can't You?|url=https://www.discovermagazine.com/the-sciences/if-an-electron-can-be-in-two-places-at-once-why-cant-you|website=[[Discover Magazine]]}}</ref>

Philosopher of science [[Robert P. Crease]] says that MWI is "one of the most implausible and unrealistic ideas in the history of science" because it means that everything conceivable happens.<ref name="ball"/> Science writer [[Philip Ball]] calls MWI's implications fantasies, since "beneath their apparel of scientific equations or symbolic logic, they are acts of imagination, of 'just supposing{{'"}}.<ref name="ball"/>

Theoretical physicist [[Gerard 't Hooft]] also dismisses the idea: "I do not believe that we have to live with the many-worlds interpretation. Indeed, it would be a stupendous number of parallel worlds, which are only there because physicists couldn't decide which of them is real."<ref>{{Cite news|last=Melinda|first=Baldwin|date=2017-07-11|title=Q&A: Gerard 't Hooft on the future of quantum mechanics|journal=Physics Today|issue=7 |url=https://physicstoday.scitation.org/do/10.1063/PT.6.4.20170711a/abs/|language=EN|doi=10.1063/PT.6.4.20170711a}}</ref>

[[Asher Peres]] was an outspoken critic of MWI. A section of his 1993 textbook had the title ''Everett's interpretation and other bizarre theories''. Peres argued that the various many-worlds interpretations merely shift the arbitrariness or vagueness of the collapse postulate to the question of when "worlds" can be regarded as separate, and that no objective criterion for that separation can actually be formulated.<ref>{{Cite book|last=Peres|first=Asher|title=[[Quantum Theory: Concepts and Methods]]|publisher=Kluwer Academic Publishers|year=1995|isbn=0-7923-2549-4|pages=374|author-link=Asher Peres}}</ref>