[vankessel]

Thank you. I really like the point you are making, but I am unsure about a lack of cause and effect. When I think of cause and effect, I think of it as taking the state of the universe from state t+0 to t+1 using the laws of physics. All of it being deterministic, except for quantum mechanics. This indeterminism in QM creating the branches allowing one to escape death.

Couldn't believing in quantum immortality be compatible with this? You could do things like firing a gun to your head, and it would misfire every time. You could jump off a building and would land in a passing open-topped garbage truck full of soft material. You'd experience all sorts of crazy coincidences, but all of them plausibly deniable and within the framework of cause and effect as we know it.

With that said, I feel like what you are saying is true but can not fully formulate my thoughts on it yet. I agree completely that you can never have logical certainty of it's truth, but I'm not certain it's contingent on it being true. Perhaps we should instead say that QI is either true or false, but we can never prove which? This removes the implication but still makes sense in the context of Godel's first incompleteness theorem.

[Iv]

I find the whole QI following so weird... Do people really argue that QM can provide cartoon-like effects like a convenient truck under the bridge?

Do people really argue that conscience is so special that the universe refuses to end one?

The universe don't differentiate between a dead human and a living one. From a QM point of view, both body masses, correctly placed, can work as an "observer" to cause waveform collapse.

[vankessel]

Well, yes. Those examples were chosen to be cartoonish stereotypes. Extremely statistically unlikely events would look... strange, to say the least. Sort of like the flapping of a butterfly's wings resulting in a hurricane.

Also there has been some discussion about how quantum events would only affect the microscopic and the macroscopic would remain the same. This is false, quantum events can only occur in the microscopic, but their effects can propagate to the macroscopic in ways beyond our comprehension. Take the experiment itself, the outcome of a quantum event propagates to the life or death of a human being.

Lastly there have also been remarks about how death needs to be guaranteed because QI only promises consciousness not health or a lack of suffering. I will address that here too. That is a perfectly fine way of viewing QI but there is a distinction we should formalize to make it clear.

Greedy QI and Perfect QI.

Greedy QI just branches from the present moment to whichever consciousness will persist. This can result in a local optimum where you are maimed but alive.

Perfect QI always picks the best branch point of every present moment to account for all future possibilities. I argue this in assumption #2. Once the bullet has say, pierced the brain stem, there is no greedy choice from there that will save you. Perfect QI likely won't maim you as that would limit your survival possibilities. It's the global optimum.

There is still a problem with this though. What if there is more than one timeline where you always live? How is one chosen? My guess would be either it's randomly chosen, or there is only one timeline. Let me elaborate on the latter with a mathematical analogy.

You have an infinite list of real numbers. These numbers represent different timelines, the value being how long you survive. If you order them, you can always find a larger finite number looking at the next one, but none of them are infinite in value. Since QI assumes immortality not longevity we will assume the limit of this ordered list is infinity and not a finite number. Thus there is one reality in which you live infinitely, and that's the limit of this ordered set. The only chance for approaching this limit is through a mechanism like perfect QI.

[jerf]

"Do people really argue that conscience is so special that the universe refuses to end one?"

QI doesn't protect consciousness. Its argument applies to any quantum state, described by any arbitrarily complicated acceptance function of that state. The QI argument implies that you can pick up a rock, and that there exists some set of universes in which that rock will survive indefinitely, exactly as it is now, to any degree of accuracy you care to specify. It's just the more precise your specification gets, the lower the probability mass is.

That's why in my other message, I say QI only promises consciousness. Technically, there are universes in which by sheer quantum chance you are in fact healthy and happy indefinitely. It's just that "a healthy and happy body" is incomprehensibly more orders of magnitude more unlikely than being stuck in whatever constitutes the minimally conscious body. And in fact, the latter isn't a unique construct either. It's actually a function of the selectivity you apply to the acceptance function; you have the universes in which you are conscious enough to realize your plight, but they're dominated by the universes in which you are too minimally conscious to even realize that, which are in turn dominated by the universes in which you are just not conscious. But those are excluded from your consciousness' future states, which means your consciousness is left over with whatever else is left.

The distinctive thing that consciousness adds to the argument is merely that if you metaphorically drew out the future universes in which your consciousness survives, there is something meaningful (to us, anyhow!) "inside" that set. You can do the same thing to the rock as I described above, but there isn't really anything "inside" that set; it's just the rock and nothing else. Excepting of course that vanishing fraction of the universes in which quantum processes drive the rock to become conscious by any definition of your choice, of course.

(Another thing I'd point out is that for this discussion, I have no concern about what your definition of "consciousness" is. The argument works regardless of your definition, it just tweaks the exact non-zero numbers that come out.)

[Iv]

Why should it bring more comfort than knowing, e.g. that there are alternative universes where my deceased loved ones are alive?

There seems to be a belief that our consciousness will "jump" to an alive alternative. I think that's a strong misconception of what many-worlds interpretation says.

Talking about misconceptions, without having more than superficial background in QM, I doubt that being able to consider even very unlikely outcomes allows you to discard macroscopic causality altogether, which QI basically requires.

[jerf]

"Why should it bring more comfort than knowing, e.g. that there are alternative universes where my deceased loved ones are alive?"

I'm not sure you're reading my posts for what they say, rather than what you expect them to say. I think QI is horrible, as in, more suited to horror stories, than something that offers comfort. Nor do I discuss any sort of "jumping".

[jerf]

"Couldn't believing in quantum immortality be compatible with this? You could do things like firing a gun to your head, and it would misfire every time. You could jump off a building and would land in a passing open-topped garbage truck full of soft material. You'd experience all sorts of crazy coincidences, but all of them plausibly deniable and within the framework of cause and effect as we know it."

I think one of the several issues I have with this article is that you're measuring survival in human terms, not quantum terms. One of the secret constraints in the quantum suicide thought experiment is that your method of death must be literally 100% guaranteed, and ideally for the argument, instantaneous from the point of view of your consciousness. (That is, for our consciousness's sake, I don't think Planck time is particularly relevant; more human time frames are relevant.) Sometimes this is expressed as sitting next to an atom bomb rather than just a gun.

But, even then, as a pragmatic matter, a real person trying to perform this experiment would need to be concerned about the quantum probability that the bomb does indeed go off, but leaves them maimed because it didn't exactly explode fully, but the explosives half-detonate and the uranium goes only a bit critical, spraying you with radiation and seriously injuring you but not actually killing you. As you sit there next to your quantum number generator, you are indeed systematically pruning the quantum state space of the worlds in you do actually die, but the remaining quantum state space has a great deal more than just "you get up and turn off the quantum number generator once you are satisfied".

Similarly, a gun can do a lot more than just fire and kill you, or not fire and leave you harmless. It could fire, and put what should be a fatal hole in your head, but the bare minimum quantum events occur to keep you just barely conscious.

As you prune away all the likelihoods, you're amplifying the probably of everything other than what you pruned away, not just the human-conceivable events. The harder and more successfully you prune, the weirder what's left over gets. Given that you've set up a situation in which you've got a gun aimed at your head or an atom bomb or what have you, those "weird" situations are likely to be unpleasant.

Of course, if QI and the multiple worlds hypothesis is correct, this all happens anyhow all the time, and seeing our family or friends just suddenly explode for no reason is something we are literally experiencing all the time, just with such a low probability that it hasn't happened yet. But, somewhere in the great multiverse, there's a set of people who read this message and it is immediately followed by, say, their left hand just disintegrating. Take heart... for some yet smaller fraction of you, it will also immediately fix itself.