Editing Quantum suicide and immortality (section)

=== Analysis by other proponents of the many-worlds interpretation ===

Physicist [[David Deutsch]], though a proponent of the many-worlds interpretation, states regarding quantum suicide that "that way of applying probabilities does not follow directly from quantum theory, as the usual one does. It requires an additional assumption, namely that when making decisions one should ignore the histories in which the decision-maker is absent....[M]y guess is that the assumption is false."<ref>{{cite book |last=Deutsch |first=David |year=2011 |chapter=The Beginning|title=The Beginning of Infinity |publisher=Penguin Group}}</ref>

Tegmark now believes experimenters should only expect a normal probability of survival, not immortality. The experimenter's [[probability amplitude]] in the wavefunction decreases significantly, meaning they exist with a much lower measure than they had before. Per the [[anthropic principle]], a person is less likely to find themselves in a world where they are less likely to exist, that is, a world with a lower measure has a lower probability of being observed by them. Therefore, the experimenter will have a lower probability of observing the world in which they survive than the earlier world in which they set up the experiment.<ref name="Tegmark2014"/> This same problem of reduced measure was pointed out by [[Lev Vaidman]] in the ''[[Stanford Encyclopedia of Philosophy]]''.<ref>{{cite web |last1=Vaidman |first1=Lev |date=2018 |title=Many-Worlds Interpretation of Quantum Mechanics |url=https://plato.stanford.edu/entries/qm-manyworlds/ |website=The Stanford Encyclopedia of Philosophy |publisher=Metaphysics Research Lab, Stanford University |publication-place=Stanford, California}}</ref> In the 2001 paper, "Probability and the many-worlds interpretation of quantum theory", Vaidman writes that an agent should not agree to undergo a quantum suicide experiment: "The large 'measures' of the worlds with dead successors is a good reason not to play." Vaidman argues that it is the instantaneity of death that may seem to imply subjective survival of the experimenter, but that normal probabilities nevertheless must apply even in this special case: "[i]ndeed, the instantaneity makes it difficult to establish the probability postulate, but after it has been justified in the wide range of other situations it is natural to apply the postulate for all cases."<ref>{{cite arXiv |last1=Vaidman |first1=Lev |title=Probability and the Many-Worlds Interpretation of Quantum Theory |date=13 November 2001|eprint=quant-ph/0111072 }}</ref>

In his 2013 book ''The Emergent Multiverse'', Wallace opines that the reasons for expecting subjective survival in the thought experiment "do not really withstand close inspection", although he concedes that it would be "probably fair to say [...] that precisely because death is philosophically complicated, my objections fall short of being a knock-down refutation". Besides re-stating that there appears to be no motive to reason in terms of expectations of experience instead of expectations of what will happen, he suggests that a [[decision theory|decision-theoretic]] analysis shows that "an agent who prefers certain life to certain death is rationally compelled to prefer life in high-weight branches and death in low-weight branches to the opposite."<ref name=wallace>{{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 |pages=369–372 |url=https://books.google.com/books?id=mqfnu1o26cEC |language=en}}</ref>

Physicist [[Sean M. Carroll]], another proponent of the many-worlds interpretation, states regarding quantum suicide that neither experiences nor rewards should be thought of as being shared between future versions of oneself, as they become distinct persons when the world splits. He further states that one cannot pick out some future versions of oneself as "really you" over others, and that quantum suicide still cuts off the existence of some of these future selves, which would be worth objecting to just as if there were a single world.<ref>{{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>