Editing Many-worlds interpretation (section)

== Speculative implications ==
{{see also|Parallel universes in fiction}}

DeWitt has said that Everett, Wheeler, and Graham "do not in the end exclude any element of the superposition. All the worlds are there, even those in which everything goes wrong and all the statistical laws break down."<ref name="dewitt71" /> Tegmark affirmed that absurd or highly unlikely events are rare but inevitable under MWI: "Things inconsistent with the laws of physics will never happen—everything else will&nbsp;... it's important to keep track of the statistics, since even if everything conceivable happens somewhere, really freak events happen only exponentially rarely."<ref name="TegmarkEverything">{{Cite web |last=Tegmark |first=Max |title=The Universes of Max Tegmark |url=https://space.mit.edu/home/tegmark/crazy.html |access-date=2023-08-26 |website=space.mit.edu}}</ref> [[David Deutsch]] speculates in his book ''[[The Beginning of Infinity]]'' that some fiction, such as [[alternate history]], could occur somewhere in the [[multiverse]], as long as it is consistent with the laws of physics.<ref name="beginning">David Deutsch. ''Beginning of Infinity'', Penguin Books (2011), {{ISBN|978-0-7139-9274-8}}, p. 294.</ref><ref name="GribbinSixImpossibleThings">[[John Gribbin]], ''Six Impossible Things'', Icon Books Limited (2021), {{ISBN|978-1-7857-8734-8}}.</ref>

According to Ladyman and Ross, many seemingly physically plausible but unrealized possibilities, such as those discussed in other scientific fields, generally have no counterparts in other branches, because they are in fact incompatible with the universal wave function.<ref name=ladymanross/> According to Carroll, human decision-making, contrary to common misconceptions, is best thought of as a classical process, not a quantum one, because it works on the level of neurochemistry rather than fundamental particles. Human decisions do not cause the world to branch into equally realized outcomes; even for subjectively difficult decisions, the "weight" of realized outcomes is almost entirely concentrated in a single branch.<ref name=deeplyhidden/>{{rp|214-216}}

''[[Quantum suicide]]'' is a [[thought experiment]] in [[quantum mechanics]] and the [[philosophy of physics]] that can purportedly distinguish between the [[Copenhagen interpretation]] of quantum mechanics and the many-worlds interpretation by a variation of the [[Schrödinger's cat]] [[thought experiment]], from the cat's point of view. ''Quantum immortality'' refers to the subjective experience of surviving quantum suicide.<ref name="mit_edu">{{cite web |url=http://space.mit.edu/home/tegmark/quantum.html#immortality |title=Quantum immortality |last=Tegmark |first=Max |date=November 1998 |access-date=25 October 2010 }}</ref> Most experts believe the experiment would not work in the real world, because the world with the surviving experimenter has a lower "measure" than the world before the experiment, making it less likely that the experimenter will experience their survival.<ref name=wallace2012>{{cite book |last1=Wallace |first1=David |title=The Emergent Multiverse: Quantum Theory According to the Everett Interpretation |date=2012 |publisher=Oxford University Press |isbn=978-0-19-954696-1 }}</ref>{{rp|371}}<ref name=vaidman_stanfordencyclopedia/><ref name=deeplyhidden>{{cite book |last=Carroll |first=Sean |url=https://books.google.com/books?id=f16IDwAAQBAJ |title=Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime |date=2019-09-10 |publisher=Penguin |isbn=978-1-5247-4302-4 |language=en }}</ref><ref>{{cite book |last=Deutsch |first=David |year=2011 |chapter=The Beginning |title=The Beginning of Infinity |publisher=Penguin Group }}</ref>