For (1) the multiverse needs to be immensely larger than our universe, by a factor of at least 10^10^6 or so "instances". The exact double exponent depends upon how closely people have to match before it's reasonable to consider them to be essentially the same person. Perhaps on the order of millions of data points is enough, maybe more are needed. Evidence for MWI is nowhere near strong enough to justify this level of granularity in the state space and it doesn't generalize well to space-time quantization so this probably isn't enough. Tegmark's hypothesis would be fine, though.
You don't really need assumption (2). Simulations are not required, all it takes is any nonzero weight (no matter how small) of you not actually dying given each timeline of preceding experience. That includes possibilities like "it was all actually a dream", a physical mock-up of your life, drug-induced states, and no doubt unboundedly many that none of us can imagine.
(3) is definitely required. With (1) there are almost certainly enormous numbers of people essentially identical to you and your experiences, who have the experience of dying and then waking up and you don't know whether you're going to turn out to be one of them, but those are immensely outweighed by those who don't live on.
Sure, those who do live on will think "wow I wasn't expecting this!" and they will remember being you but without (3) they are actually someone else and their future will almost certainly be different from anything you would have experienced had you lived.
For (1) the multiverse needs to be immensely larger than our universe, by a factor of at least 10106 or so “instances”. The exact double exponent depends upon how closely people have to match before it’s reasonable to consider them to be essentially the same person. Perhaps on the order of millions of data points is enough, maybe more are needed. Evidence for MWI is nowhere near strong enough to justify this level of granularity in the state space and it doesn’t generalize well to space-time quantization so this probably isn’t enough.
Why? Even without unphysically ordering arbitrary point-states, isn't the whole splitting behavior creates at least all subjectively-distinguishable instances?
I'm not saying that it's impossible, just that we have no evidence of this degree of multiplicity. Even if the MWI interpretation was correct, the underlying state space could be very much coarser than this thought experiment requires without any effect on experimental observations at all. Or something even weirder! Quantum theories are an approximation, and pushing an approximation to extremes usually gives nonsense.
Saying that there are literally uncountably infinite many real states is going far beyond the actual evidence. We don't - and can't - have any evidence of actual infinity or indeed any physically existing entities of number anything like 10^million.
Unfortunately the nature of reality belongs to the collection of topics that we can't expect the scientific method alone to guide us on. But perhaps you agree with that, since in your second paragraph you essentially point out that practically all of mathematics belongs to the same collection.
What does it mean to "should expect" something, if your identity is transmitted across multiple universes with different ground truths?
The same way one "should expect" to wake up from sleep the next morning. "You" of this instant is a particular observer-moment that is being computed in a multitude of quantum branches or universes. Here the argument is that when you die, there will be quantum branches or other universes computing observer-moments of you being revived, and hence you are guaranteed to be "revived" after death from a subjective point of view.
Could you elaborate on the ground truth part? I'm not sure I understand.
1I'm not convinced that there is a single "way" one should expect to wake up in the morning. If we're talking about things like observer-moments and exotic theories of identity, I don't think we can reliably communicate by analogy to mundane situations, since our intuitions might differ in subtle ways that don't matter in those situations.
For instance, should I believe that I will wake up because that will lead me to make decisions that lead to world-states I prefer, or should I expect to wake up because it is true that I will probably wake up? If the latter, does that just mean that there will exist an observer-moment in my bed tomorrow that is a close match to my current self, or am I actually expecting to be the same as that observer-moment in some important sense that that would not apply to other observer-moments in the same epistemic state? Different answers to these questions will mostly add up to similar bedtime behavior, but they diverge if the situation gets far out of distribution.
If I just care about doing things that help similar observer-moments, the assumption that "I" am distributed across multiple worlds doesn't matter much. I'll just act under the assumption that I'll live another day (or eventually be revived), and in worlds I don't, there aren't any observer-moments I care about to complain I guessed wrong. In that sense, I "should" expect to continue to exist (But if you're selfish enough, this means you "should" expect to be immortal even in a single, deterministic universe. When you inevitably die, you aren't around to regret your expectation!) But if you only "should" expect things as much as they are likely to actually happen, being distributed over multiple universes is a big issue, since it is likely that in any given time period you will actually die in some universes AND actually survive in others. You could decide to weight your belief according to how many universes you expect to survive in, but only if you have a measure over universes. (this is also an issue for the first kind of "should"; once you decide to act like you'll live, you might find yourself facing decisions that incline you to weigh one set of worlds against another.)
This is quite similar to the "swampman" thought experiment (https://en.wikipedia.org/wiki/Donald_Davidson_(philosopher)).
My thoughts: Assuming there is no subjective experience after death (no afterlife or anything), then it is sort of trivial that subjective experience ends at death, so you don't ever experience it.
Now, my read on your argument is that in a sufficiently big universe or multiverse, there will be many "mes" with exactly the same subjective experiences so far, and that whenever one (or a large number) of "mes" die there will be some others who are narrowly saved at the last moment, just as they wheeze their last breath an alien turns up and heals them or whatever. Or they were in a simulation the whole time or similar.
However, it remains the case that before the death there were N copies, and afterwards there were N-1. Its not like you "merged with" or "snapped into" the surviving ones. You are not causally propagating yourself into them. Its just you have accepted a world view where it is possible to likely that there are people arbitrarily similar to you.
My feeling is that its like this analogy. Imagine that in the near future all records of the works of Shakespeare (all of them, including all quotes) are lost forever. But that, it just so happens that by complete coincidence there are pebbles on a beach in another galaxy, that can be read in binary (dark/pale pebbles 1/0) to symbolise the full works of Shakespeare to the letter. Does that make it any less of a loss that the works were lost here on Earth?
So, what's up with my apparent nonexistence in my past? It seems slightly weird that I had some starting point but wouldn't have ending point. Also I'm really confused by, like, subjective time being a thing, if you assume this post is correct description of the universe.
If "I" am dying, but the other supposed instances of "me" are not, then the similarity between us has already been lost. "I" am on my own and will die alone.
See the argument for quantum immortality, mine is similar to that but involves revival simulations in other worlds rather than just future branches.
The same argument refutes quantum immortality, or at least removes its attractiveness. Suppose I am facing imminent death. For example, I have a terminal illness and within a few days I am sure to expire. What hypothetical being differs from me in a single piece of quantum uncertainty resolving one way rather than another? Someone with that terminal illness who in a few days will expire almost as certainly as I will. You have to go very far from that person on the death ward to reach someone who is hale and hearty, and what does that person have to do with me? The most similar person to me who is still alive when I die is one who is just about to die. And there I will be stuck, endlessly dying until some other outcome rises to greater probability than my increasingly unlikely survival, and will that outcome be any more welcome? That is what quantum immortality would look like. I believe this point has been made by others, that QI should be considered horrifying rather than an escape from death.
The closest we have to coexisting but identical persons in this world is identical twins. I have never heard of anyone going to sleep as one of a pair of twins and waking up as the other.
3There is non-zero measure on a branch that starts with you terminally ill and gradually proceeds to you miraculously recovering. So if you consider normally recovered you to be you, nothing stops you from considering this low-measure you to also be you.
I have never heard of anyone going to sleep as one of a pair of twins and waking up as the other.
According to MWI everyone wakes up as multiple selves all the time.
To adapt Woody Allen, I don’t want to achieve immortality by imagining that someone else is me, I want to achieve immortality by not dying.
The point of the third assumption is that those revival simulations are not just similar to you, but actually "you". "You" of this instant is a particular observer-moment that is being computed in a multitude of quantum branches or universes.
Well, that is your third assumption. But it requires that the multiple instances are identical: if one is dying, all are. If one is revived, all are.
1What we want is orthogonal though, right? Unless you think that metaphysics is so intractable to reason about logically that the best we can do is go by aesthetics.
I believe this point has been made by others, that QI should be considered horrifying rather than an escape from death.
I agree, though this misses the point since I never rendered a value judgment on whether being immortal this way is "good" or "bad". I was simply stating a neutral argument as to why we are probably immortal if we accept the three assumptions I laid out.
Yes, this seems to be the implication from this assumptions.
This is one of the reasons why I'm very confident that assumption 3. is either wrong, or "not even wrong".
I'm not sure what (if any) action-relevant point you might be making. If this is supposed to make you less concerned about death, I'd point out that the thing to care about is your measure (as in quantum immortality), which is still greatly reduced.
E.g. choose (1% death, 99% totally fine) action instead of (0.1% paralyzed and in pain, 99.9% totally fine) action. Or something like that, your bad outcomes become not death but entrapment in suffering.
That leads you to always risk your life if there's a slight chance it'll make you feel better … Right? E.g. 2% death, 98% not just totally fine but actually happy, etc., all the way to 99.99% death, 0.01% super duper happy
Well, let's reason step by step. I certainly never died before*. This post proposes that i will never die in the future. But i certainly experienced quite bad states, really really repulsive ones. Not sure about happy ones, i think don't actually endorse pulling myself towards any state such described? I kinda want normal, neutral state. Like, it's as if i have states i strongly want to avoid, but no states i want to go into.
Alsooo, this post kind of doesn't explain why there is time or my apparent non existence in my past. Or what is the measure of me or why it's should be compelling to preserve it/expand it. Or maybe it's a force that should be a consideration in all tradeoffs, like, you want to be happy? But this thing pulling you towards to be smeared over large amount of branches. Or something. So you should think how it affects or trades off again things you want.
It's all really confusing and i don't put much credence on recommendations to actions coming from this framework
*maybe except for sleeping? and then got resurrected in my waking body?
Yea I'm not really trying to make any action-relevant point, just pointing out that if we accept three premises which are not that uncommonly held here on LessWrong we get something weird. Also if anything this makes me more scared of death since I would have no idea or control of how I am "respawned" and by whom.
And FWIW I'm skeptical of the reduced measure response to quantum immortality, it feels like cope to me. I don't intuitively see why I should not care about my anticipated experiences more than some mathematical construct.
Makes sense! And yeah, IDK, I think the concept of 'measure' is pretty confusing itself and not super convincing to me, but if you think through the alternatives, they seem even less satisfying.
It's not necessary to bring quantum physics into it. Isomorphic consciousness-structures have the same experience (else they wouldn't be isomorphic, since we make their experience part of them). The me up to the point of waking up tomorrow (or the point of my apparent death) is a such a structure (with no canonical language unfortunately; there are infinitely many that suffice), and so it has an elementary class, the structures that elementarily extend it, in particular that extend its experience past tomorrow morning.
+2 for brevity! A couple more explorations of this idea that I didn't see linked yet. They are more verbose, but in a way I appreciate.
- The mathematical universe: the map that is the territory. I'd love to meet the author of this. They also wrote the excellent If a tree falls on Sleeping Beauty.... Sadly they haven't used that account in many years.
- Simulation, Consciousness, Existence (Hans Moravec)
If you want to explore this idea further, I'd love you join you.
I think 1 and 2 are reasonable but I struggle to accept 3. I’m not sure that consciousness transfers that way at all, but there’s no way for anyone to realize this other then the consciousness that was not transferred. https://youtu.be/JMkrrjKf5AE is an excellent video by Jacob Geller on this exact idea.
This is similar to the quantum suicide thought experiment:
https://en.wikipedia.org/wiki/Quantum_suicide_and_immortality
Check out the Max Tegmark references in particular.
1
Epistemic Status: ~70% confidence, hoping to get some feedback.
I'm going to argue that if we accept three controversial (but not outlandish) assumptions to be true, then subjective death (the cessation of conscious experiences identifying themselves as "you") is impossible. I will keep this post as concise as possible.
Here are the three assumptions:
Given assumption 1, somewhere "out there" (e.g. in a different Everett branch), there will be worlds that contain "revival simulations" of you (simulations of you being revived and regaining consciousness after your death).
Given assumption 2, these simulations will be conscious and have subjective experience.
Given assumption 3, these revival simulations of you are technically "you" since "you" of this instant is a particular observer-moment that is being computed in a multitude of quantum branches or universes. Your identity is transmitted through the continuity of similar observer-moments since these simulations possess the same memories as you before you died (and hence connect with your last observer moment).
Similar to how the quantum immortality argument says that even though your "reality measure" is reduced after an experiment, you are guaranteed to survive from your perspective because you cannot subjectively experience the branches where you die. Here the argument is that when you die, there will be quantum branches or other universes computing observer-moments of "you" experiencing a revival. Hence you should always expect to be revived after death.
These conclusions sound pretty crazy to me intuitively, but if one accepts the assumptions (whether or not those assumptions are true is outside the scope of this post), these conclusions feel quite straightforward.