There is a quantum mechanical property which you may not be aware of. It is incredibly hard, if not impossible to cause two worlds to merge. (Clarification: It may be possible when dealing with microscopic superposed systems, but I suspect it would take a god to merge two worlds which have varied as much as you describe.) There is regular merging of “worlds”, but that occurs on the quantum level between “worlds” that don’t differ macroscopically.
This is because any macroscopic difference between two worlds is sufficient for them to not be the same, and it’s not feasible to put everything back the way it was.
However, this does not apply to merging people. I suspect that most theories of personhood that allow this are not useful, though. (Why are the two near-copies not the same person, but you remain the same person after losing the small memory? That’s a strange definition of personhood.) That is, you can define personhood any way you like, and you can hack this—for example, to remove “yourself” from bad worlds. (Simply define any version of you in a bad world to not be a person, or to be a different person.) But that doesn’t mean that you can actually expect the world to suddenly become good. (Or you can, but at that point everyone starts ignoring you.)
You right—I didn’t mean the merge of quantum worlds, but mean the merge of personhoods, which could happen even in classical but infinitely large universe. I wanted to show that assuming the possibility of such merger has absurd consequences. However, this absurdity is also applicable to other calculations where the “measure of an observer” changes, as it happens in the one of important objections to the quantum immortality.
In the other words, we can’t kill the quantum immortality idea by saying “the measure will decline to infinitely small values”, as in fact, the measure could even grow if we properly calculate it.
What could be done to resolve this conundrum? We could ignore changes of absolute measure, and look only on relative measure, that is relation between shares of the different outcomes where observer is alive. For example, if QS thought experiment has 3 outcomes: a) non existence 0.9, b) winning 1000 usd with 0.09 с) losing 100 000 with 0.01 probability (e.g. injury) , we should in that case ignore (a) and compare expected utility of (b) and (c), which are +90 and −1000, so the game in this case has negative utility of −910.
Another solution is to accept that we could change our measure in the world by forgetting things, and to build something like a magic based on it. (This idea was discussed on LW as “flux universe” on a series of posts where a person had panic attacks based on idea that if he forgets parts of his personality before sleep, he would be never able to return back to his initial self.) This “magic” may look like: (1) a person learns that he has rare deadly disease. (2) he meditates and remove from his mind all clues about this fact (3) his observer-moment becomes so simple that it is equal to zillions of observer-moments of other peoples (4) if human mind is only numbers, they “merge”, (5) now he returns to awake state, but his probability to be in the world-line where he has the rare disease is equal to the level of incidents of the disease in the population, that is very low. (6) Profit. But this thing seems more absurd than quantum immortality.
Another possible solution is to get rid of the idea of identity in favor of some form of open individualism. The problem here is that most human preferences are formulated in the way that they assume existence of the some form of identity: “I want a cake”
There is a quantum mechanical property which you may not be aware of. It is incredibly hard, if not impossible to cause two worlds to merge. (Clarification: It may be possible when dealing with microscopic superposed systems, but I suspect it would take a god to merge two worlds which have varied as much as you describe.) There is regular merging of “worlds”, but that occurs on the quantum level between “worlds” that don’t differ macroscopically.
This is because any macroscopic difference between two worlds is sufficient for them to not be the same, and it’s not feasible to put everything back the way it was.
However, this does not apply to merging people. I suspect that most theories of personhood that allow this are not useful, though. (Why are the two near-copies not the same person, but you remain the same person after losing the small memory? That’s a strange definition of personhood.) That is, you can define personhood any way you like, and you can hack this—for example, to remove “yourself” from bad worlds. (Simply define any version of you in a bad world to not be a person, or to be a different person.) But that doesn’t mean that you can actually expect the world to suddenly become good. (Or you can, but at that point everyone starts ignoring you.)
You right—I didn’t mean the merge of quantum worlds, but mean the merge of personhoods, which could happen even in classical but infinitely large universe. I wanted to show that assuming the possibility of such merger has absurd consequences. However, this absurdity is also applicable to other calculations where the “measure of an observer” changes, as it happens in the one of important objections to the quantum immortality.
In the other words, we can’t kill the quantum immortality idea by saying “the measure will decline to infinitely small values”, as in fact, the measure could even grow if we properly calculate it.
What could be done to resolve this conundrum? We could ignore changes of absolute measure, and look only on relative measure, that is relation between shares of the different outcomes where observer is alive. For example, if QS thought experiment has 3 outcomes: a) non existence 0.9, b) winning 1000 usd with 0.09 с) losing 100 000 with 0.01 probability (e.g. injury) , we should in that case ignore (a) and compare expected utility of (b) and (c), which are +90 and −1000, so the game in this case has negative utility of −910.
Another solution is to accept that we could change our measure in the world by forgetting things, and to build something like a magic based on it. (This idea was discussed on LW as “flux universe” on a series of posts where a person had panic attacks based on idea that if he forgets parts of his personality before sleep, he would be never able to return back to his initial self.) This “magic” may look like: (1) a person learns that he has rare deadly disease. (2) he meditates and remove from his mind all clues about this fact (3) his observer-moment becomes so simple that it is equal to zillions of observer-moments of other peoples (4) if human mind is only numbers, they “merge”, (5) now he returns to awake state, but his probability to be in the world-line where he has the rare disease is equal to the level of incidents of the disease in the population, that is very low. (6) Profit. But this thing seems more absurd than quantum immortality.
Another possible solution is to get rid of the idea of identity in favor of some form of open individualism. The problem here is that most human preferences are formulated in the way that they assume existence of the some form of identity: “I want a cake”