What exactly does quantum immortality convey?

[KleinMoretti]

TL;DR Summary

does quantum immortality really imply immortality?

so I came across the wikipedia article for quantum immortality but after reading I still have some questions, does QI say that there is always a world where you are alive? also If I understood the article correctly the original claims was that if you committed quantum suicide and you died somehow your consciousness was trasnferred to another version of you?

some resources I found that talk about Quantum immortality.
https://iopscience.iop.org/article/10.1088/1742-6596/1936/1/012015/pdf

https://arxiv.org/pdf/2007.09847

https://www.researchgate.net/profile/Bartlomiej-Lenart/publication/345476949_Why_We_Shouldn't_Pity_Schrodinger's_Kitty_Revisiting_David_Lewis'_Worry_About_Quantum_Immortality_in_a_Branching_Multiverse/links/64ddb91d25837316ee1852b4/Why-We-Shouldnt-Pity-Schroedingers-Kitty-Revisiting-David-Lewis-Worry-About-Quantum-Immortality-in-a-Branching-Multiverse.pdf

https://physics.stackexchange.com/questions/429104/is-quantum-immortality-true

 

[Demystifier]

If I understood the article correctly the original claims was that if you committed quantum suicide and you died somehow your consciousness was trasnferred to another version of you?

No, your consciousness is split into all universes in which you are alive.

 

[KleinMoretti]

No, your consciousness is split into all universes in which you are alive.

right but does QI actually say a person is immortal as in living forever?

 

[PeterDonis]

Moderator's note: Thread moved to interpretations subforum since how QI is handled is interpretation dependent.

 

[KleinMoretti]

Moderator's note: Thread moved to interpretations subforum since how QI is handled is interpretation dependent.

doesn't it only work with MWI?

 

[Demystifier]

right but does QI actually say a person is immortal as in living forever?

No, it only says that a person will always survive a quantum version of "Russian roulette".

 

[pines-demon]

It remains unclear to me to what degree Everett believed in it, but the concept was clearly floating around. Note that some authors prefer to discuss quantum immortality as an inoffensive thought experiment, unrelated to the psychological consequences that it ensued on Everett. For the somber details see below:

From Wikipedia Quantum suicide and immortality (properly sourced):

Hugh Everett did not mention quantum suicide or quantum immortality in writing; his work was intended as a solution to the paradoxes of quantum mechanics.

Eugene Shikhovtsev's biography of Everett states that "Everett firmly believed that his many-worlds theory guaranteed him immortality: his consciousness, he argued, is bound at each branching to follow whatever path does not lead to death". Peter Byrne, author of a biography of Everett, reports that Everett also privately discussed quantum suicide (such as to play high-stakes Russian roulette and survive in the winning branch), but adds that "it is unlikely, however, that Everett subscribed to this [quantum immortality] view, as the only sure thing it guarantees is that the majority of your copies will die, hardly a rational goal."

From Paul Halpern (2015) Quantum Immortality, Medium:

Everett reportedly believed in this kind of “quantum immortality.” Fourteen years after his death in 1982, his daughter Liz took her own life, explaining in her suicide note that in some branch of the universe, she hoped to reunite with her father.

 

[gentzen]

Just like Newton's theory of light and colours doesn't say anything about colour-blindness or other topics related to the conscious experience of colour, the pure framework of QM doesn't say anything about philosophical zombies or other topics related to conscious experiences. If MWI would make specific predictions regarding the continued conscious experience of the abscence of death, this would contradict its claim to not add anything to the pure framework of QM.

Like the example of colour-blindness shows, it is possible to have testable theories concerning conscious experiences. But if a framework or theory stays silent on such matters, it is a mistake to attribute such statements to it, just because it relied on related experiences for the experiments testing it (i.e. of course Newton had to rely on his conscious perception of colour for his experiments).

 

[PeterDonis]

doesn't it only work with MWI?

As I understand it the MWI was the interpretation that inspired the concept. I don't know if that's the only interpretation that allows it, though. In any case the discussion of it belongs in this subforum.

 

[KleinMoretti]

does QI say that there is always a world where a version of you is alive?

From the physics stack link
One person said this: “
Quantum immortality is false because it fails to take into account the fact that if all versions of you in the multiverse need to be considered, then those versions with a larger amplitude should be more probable, precisely according to the Born rule.

If one assumes that the probability amplitude does not matter, then it won't matter in general, not just in processes that could lead to your death (from the point of view of other observers). It won't matter for processes that could lead to you appearing out of thin air, either. So, in many places in the universe you could fluctuate into existence with your exact memories you have here now. All these possibilities lead to sort-of Boltzmann brain versions of you, and they should all be equally likely versions of you, despite astronomically small amplitudes.

If we then correct for the flaw of not taking into account probability amplitudes, we can still stick to the assumption of always finding ourselves alive in some state in the multiverse, but now we should consider ourselves to be sampled from all states with a probability given by the Born rule. As you become older and older, versions of you that are not as old will come into play.”

The last part is what intrigues me, why would there be versions you that are younger?

 

[pines-demon]

The last part is what intrigues me, why would there be versions you that are younger?

I have no idea if this was the original meaning of that stackexchange comment, but according to relativity, even identical twins can have a different age. For the relative age to be different from zero, they just need to have a different trajectory in space-time. Meaning that if a twin moves faster with respect to Earth, it would be younger (with respect to the twin on Earth) and a twin that stays in space (far from massive gravitational fields but comoving with the Earth) will get older with respect to the twin on Earth. One could argue something like that for many-worlds but as far as I know we do not have such a clear relativistic interpretation.

Edit: for some reason I cannot reply on the comment of @Nugatory. My intention was not to expand the conversation into quantum gravity, but I tried to clarify OP question on why older-younger versions could co-exist. I modified my comment to reflect that.

 

[Nugatory]

I have no idea if this was the original meaning, but according to relativity, there would indeed be versions that do not have the same trajectory over space-time, meaning that versions of you that move fast with respect to Earth would be younger (with respect to the proper time of Earth) and version of you that stay in space (far from massive gravitational fields) will get older.

This attempt to extend an interpretation of non-relativistic QM into curved spacetime is off-topic for this thread and risks a major thread hijack. OP is asking about the alive/non-alive states and that can be discussed without bringing in any relativistic effects - please limit the discussion to that question.

 

[KleinMoretti]

putting aside QI, in MWI is there always a world where a version of you is alive? and if there are worlds where a younger version of me is present does that also mean the opposite(worlds where I'm older)?

also does MWI say every outcome that can happen will happen?

 

[pines-demon]

putting aside QI, in MWI is there always a world where a version of you is alive? and if there are worlds where a younger version of me is present does that also mean the opposite(worlds where I'm older)?

Let us put younger/older versions aside (that requires relativity), as said above that would lead to relativistic mechanics or to quantum gravity. It is unclear many-worlds interpretation can explain either of those.

also does MWI say every outcome that can happen will happen?

MWI says that every measurement that breaks a quantum superposition would lead to world branching. So (1) you cannot have outcomes that violate the laws of physics or that are not a consequence of the initial conditions (2) it does not say anything about classical events, rolling a classical die will in principle not necessarily result in world branching, there will be only one result. Most macroscopic events would not result in branching. (3) there is still some sense in which some events happen more than others but how to define frequency and probability in many-worlds is still a matter of debate.