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If MWI is correct, should we expect to experience Quantum Torment?

3 Post author: Furcas 10 November 2012 04:32AM

If the many worlds of the Many Worlds Interpretation of quantum mechanics are real, there's at least a good chance that Quantum Immortality is real as well: All conscious beings should expect to experience the next moment in at least one Everett branch even if they stop existing in all other branches, and the moment after that in at least one other branch, and so on forever.

However, the transition from life to death isn't usually a binary change. For most people it happens slowly as your brain and the rest of your body deteriorates, often painfully.

Doesn't it follow that each of us should expect to keep living in this state of constant degradation and suffering for a very, very long time, perhaps forever?

 

 

 

 

I don't know much about quantum mechanics, so I don't have anything to contribute to this discussion. I'm just terrified, and I'd like, not to be reassured by well-meaning lies, but to know the truth. How likely is it that Quantum Torment is real?

 

 

Comments (69)

Comment author: ArisKatsaris 12 November 2012 10:35:36AM *  5 points [-]

Doesn't it follow that each of us should expect to keep living in this state of constant degradation and suffering for a very, very long time, perhaps forever?

No. One can't have it both ways. If your consciousness can persist in some infinitesimal state, then one of the things it will have lost on its way to that state is the ability to feel suffering, or boredom, or a sensation of passing time or anything of the like. The ability to feel suffering isn't any more intrinsically a part of us than the ability to see colors or hear sounds.

Besides (though this a rather more far-fetched argument), at the infinitesimal state what is there to meaningfully distinguish your "degraded" dying consciousness from an as-yet-non-upgraded consciousness being born? Instead of Quantum Hell, consider the possibility of Quantum Reincarnation. ;-)

Comment author: Furcas 12 November 2012 08:39:35PM 0 points [-]

Good points!

Comment author: Mestroyer 10 November 2012 08:32:23PM 4 points [-]

If in one bazillionth of worlds, right now, you are being tortured even though in every other world you are both alive and well, and you don't care about that world because it's only one in a bazillion, there's no reason to care about that one branch more if all the rest of the branches get changed so that you're dead. The amount you care about it should be independent of the amount you care about all the other branches.

The question "Which branch will I go down?" does not specify different ways-the-world-could-be, depending on whether the answer is yes or no. It's meaningless. There is no unique part of you that goes down only one of the branches. Your brain goes down every branch. There is no ghostly essence that is funneled into the branches where you die slowly. Your brain goes into every branch, and in most of them, it dies at the most probable speed.

Comment author: CarlShulman 10 November 2012 06:22:45AM 4 points [-]

If the many worlds of the Many Worlds Interpretation of quantum mechanics are real, there's at least a good chance that Quantum Immortality is real as well

Have you read these counterarguments?

Comment author: Furcas 10 November 2012 08:28:42AM 1 point [-]

I have now, thanks.

Comment author: wedrifid 10 November 2012 06:48:21AM *  12 points [-]

If the many worlds of the Many Worlds Interpretation of quantum mechanics are real, there's at least a good chance that Quantum Immortality is real as well: All conscious beings should expect to experience the next moment in at least one Everett branch even if they stop existing in all other branches, and the moment after that in at least one other branch, and so on forever.

Yes, Quantum Immortality is "real", as far as it goes. The problem is that it is inappropriately named and leads to inappropriate conclusions by misusing non-quantum intuitions. So yes, if you plan to put yourself in a 50% quantum death-box and keep doing so indefinitely you can expect there to be a branch in which you remain alive through 100 iterations. The mistake is to consider this intuitively closer to "immortality" rather than "almost entirely dead".

Doesn't it follow that each of us should expect to keep living in this state of constant degradation and suffering for a very, very long time, perhaps forever?

No. Don't do a count on branches, aggregate the amplitude of the branches in question. We should expect to die. There happen to be an infinite (as far as we know) number of progressively more 'improbable' branches in which we are degrading but they still aggregate to something trivial. It is like a zeno's paradox.

I have no idea whether these brief expressions of intuitions that I find useful are at all helpful for you. If not then, like Carl, I recommend this post that explores related concepts with diagrams and examples. (But I'm biased!)

Comment author: Vladimir_Nesov 10 November 2012 01:12:03PM 9 points [-]

(But I'm biased!)

(How do you know? People keep saying it, seriously or not, but when one is aware of a source of a bias, it seems as easy to overcompensate as to undercompensate, at which point you no longer know that you are biased.)

Comment author: wedrifid 11 November 2012 05:09:46AM *  2 points [-]

(How do you know? People keep saying it, seriously or not, but when one is aware of a source of a bias, it seems as easy to overcompensate as to undercompensate, at which point you no longer know that you are biased.)

I don't, and I'm sufficiently confident regarding the relevance of said post that a little doubt regarding under or over confidence matters little. On top of that I'm no more biased regarding what I wrote in the past than what I write in any comment I am writing now so additional warnings of bias for a reference call rather than inline text is largely redundant.

That was a colloquial usage not a lesswrongian one. It is sometimes appropriate to lampshade self-references so that it does not appear that one is trying to double-count ones own testimony.

Comment author: Vladimir_Nesov 11 November 2012 05:28:33AM *  1 point [-]

Certainly (hence "seriously or not"). It just irks me when people say things whose literal interpretation translates into wrong or meaningless statements, particularly when those statements are misleading or wrong in a non-obvious way. So my issue is with (the use of) such statements themselves, not the intent behind their usage, which in most cases doesn't take the literal interpretation into account. (It's usually possible to find a substitute without this flaw.)

Comment author: wedrifid 11 November 2012 05:41:29AM 0 points [-]

Certainly. It just irks me when people say things whose literal interpretation translates into wrong or meaningless statements

This example fits into a third category. That is, the colloquial meaning is valid, the lesswrong/OvercomingBias connotations are misleading but it is in fact technically true. I am, after all, biased about my own work and that is something that a reader should consider when I link to it. Assuming no difference in prior impressions of Carl and I Carl_Shuman's link should be weighted slightly differently than my own.

I agree that I'd be best served to use different wording due to the potentially distracting connotations (do you have suggestions?) but I disagree regarding the actual technical wrongness of the statement.

Comment author: Vladimir_Nesov 11 November 2012 01:53:26PM *  0 points [-]

Wait, what did you mean by "I don't" in the previous comment then? I understood that comment as confirming that you don't know that you are biased, but in this comment you say "I am, after all, biased about my own work".

To clarify: by "biased", I mean a known direction of epistemic distortion, a belief that's known to be too strong or too weak, a belief that's not calibrated, and is on the wrong side in a known direction. If the direction of a bias is unknown, it doesn't count as a bias (in the sense I used the word).

By this definition, knowing that you're biased means knowing something about the way in which you're biased, that can be used to update the belief until you no longer have such actionable information about its updated state. For example, if you expect that you estimate the quality or relevance of your own post as higher than its actual quality or relevance, this is actionable information to adjust your estimation down. After you do that, you will no longer know whether the adjusted estimation is too high or too low, so you are no longer biased in this sense.

(I guess the confusion/disagreement comes from the difference in our usage of the world "bias". What do you mean by "biased", such that you can remain biased about your own work even after taking that issue into account?)

(I wasn't able to unpack the statement "That is, the colloquial meaning is valid, the lesswrong/OvercomingBias connotations are misleading but it is in fact technically true.", that is I don't know what specifically you refer to by "colloquial meaning", "LW/OB connotations".)

Comment author: wedrifid 11 November 2012 02:16:06PM 1 point [-]

Wait, what did you mean by "I don't" in the previous comment then? I understood that comment as confirming that you don't know that you are biased, but in this comment you say "I am, after all, biased about my own work".

"I can not reliably state the nature or direction of whatever biases I may have. Even if I was entirely confident regarding the bias I should and in fact do expect others to bear that potential bias in mind."

Comment author: Furcas 10 November 2012 08:13:54AM *  3 points [-]

I've just finished reading your post. Basically what is says is, if I care about reality I should care about all future branches, not just the ones where I'm alive (or have achieved some desired result, like a million dollars). Okay, I get that. I do care about all future branches (well, the ones I can affect, anyway). But here's the thing: I care even more about the first-person mental states that I will actually be/experience.

Let's say that a version of me will be tortured in branch A, while another version of me will be sipping his coffee in branch B. From an outside perspective, it's irrelevant (meaningless, even) which version of me gets tortured; but if 'I' 'end up' in branch A, I'll care a whole lot.

So yeah, if I don't sign up for cryonics and if Aubrey de Grey and Eliezer slack off too much, I expect to die, in the same sense that I don't expect to win the lottery. I also expect to actually have the first-person experience of dying over the course of millenia. And I care about both of these things, but in different ways. Is there a contradiction here? I don't think there is.

Comment author: Vladimir_Nesov 10 November 2012 01:27:07PM *  1 point [-]

The two senses of "care" are different, and it's dangerous to confuse them. (I'm going to ignore the psychological aspects of their role and will talk only about their consequentialist role.) The first is relevant to the decisions that affect whether you die and what other events happen in those worlds, you have to care about the event of dying and the worlds where that happens in order to plan the shape of the events in those worlds, including avoidance of death. The second sense of "caring" is relevant to giving up, to planning for the event of not dying, where you no longer control the worlds where you died, and so there is no point in taking them into account in your planning (within that hypothetical).

The caring about the futures where you survive is an optimization trick, and its applicability depends on the following considerations: (1) the probability of survival, hence the relative importance of planning for survival as opposed to other possibilities, (2) the marginal value of planning further for the general case, taking the worlds where you don't survive into account, (3) the marginal value of planning further for the special case of survival. If, as is the case with quantum immortality, the probability of survival is too low, it isn't worth your thought to work on the situation where you survive, you should instead worry about the general case. Once you get into an improbable quantum immortality situation (i.e. survive), only then should you start caring about it (since at that point you do lose control about the general situation), and not before.

Comment author: MugaSofer 10 November 2012 07:09:43PM *  0 points [-]

What about anthropics? Should we care more about the worlds where we exist?

EDIT: Wait, that's nonsense.

Comment author: wedrifid 11 November 2012 03:58:34AM 3 points [-]

What about anthropics? Should we care more about the worlds where we exist?

EDIT: Wait, that's nonsense.

I'd say "ridiculous", not "nonsense". An agent certainly could care about said worlds and not about others. Yvain has even expressed preferences along these lines himself and gone as far as to bite several related bullets. Yet while such preferences are logically coherent I would usually think it is more likely that someone professing them is confused about what they want.

Comment author: MugaSofer 12 November 2012 03:57:36PM 1 point [-]

I would usually think it is more likely that someone professing them is confused about what they want.

Indeed. I was thinking about subjective probabilities, without noticing that what I expect to observe isn't what I expect to happen when dealing with anthropics.

I was pretty tired ...

Comment author: Pentashagon 11 November 2012 07:55:14PM 0 points [-]

Yes, Quantum Immortality is "real", as far as it goes. The problem is that it is inappropriately named and leads to inappropriate conclusions by misusing non-quantum intuitions. So yes, if you plan to put yourself in a 50% quantum death-box and keep doing so indefinitely you can expect there to be a branch in which you remain alive through 100 iterations. The mistake is to consider this intuitively closer to "immortality" rather than "almost entirely dead".

As far as I know I am already "almost entirely dead" in all possible worlds, so playing with the scant epsilon of universes I exist in doesn't seem like too much of a problem. If there were a way to narrow my measure of existence down to only a single universe in which only the very best things ever happened it seems like that would have the highest utility of any solution. If such a best universe exists it is very, very unlikely. My expected value from its existence is consequently very, very little unless I can prevent my experience in lesser universes.

The questions are twofold: Can quantum suicide select such a best universe (is there a cause of the very best things happening that involves continually trying to kill myself; it seems contradictory) and if so, is it the most likely or quickest way to experience such a universe? Clearly an even better goal would be a future where all universes are the best possible universe, but the ability to accomplish that does not seem likely. I lack a sufficient understanding of quantum mechanics (and the real territory) to answer these questions.

No. Don't do a count on branches, aggregate the amplitude of the branches in question. We should expect to die. There happen to be an infinite (as far as we know) number of progressively more 'improbable' branches in which we are degrading but they still aggregate to something trivial. It is like a zeno's paradox.

This is something of a paradox because my dead branches won't experience anything, leaving my experience only in the branches where I live. I should expect to experience near-death, but I should never expect to experience being dead. So a more useful expectation is what my future self will experience in 100 years, 1,000 years, or 1,000,000 years. Probably I will have died off in all but an epsilon of future possible universes, but what will those epsilon be like? They are the ones that matter.

Comment author: Mitchell_Porter 10 November 2012 09:30:55AM 8 points [-]

How likely is it that Quantum Torment is real?

The more conventional perspective on QM is of a single nondeterministic world or of a single world in which events have subquantum causes. From this perspective "quantum torment" - lingering indefinitely in a near-death state - is logically possible but inconceivably improbable, something that wouldn't happen even if you reran the history of the cosmos a googol times, because it involves the quantum dice (whether deterministic or nondeterministic) repeatedly coming up just the right way to prevent your body from finally giving up the ghost.

In a many-worlds theory all logical possibilities are supposed to happen, but the empirically validated probabilities still have to be respected. That is, we don't see all possible events occurring with equal probability, we see them occurring with probabilities given by the Born rule of QM. How to justify this within MWI is a major problem, one of several that the theory faces. But assuming that it is resolved, then the frequency with which quantum torment is realized in the multiverse must be the same as the probability with which it is expected in single-world QM, i.e. it represents a vanishingly small fraction of worlds. In the vast, vast majority of worlds you just die.

Comment author: lukstafi 10 November 2012 02:38:28PM 2 points [-]

If someone is an "identity freak", they need to condition the distribution on "person X is alive" (where "X" -- the person of interest). And now the question is whether the average health deteriorates "as time goes to infinity" -- it probably deteriorates to some minimum livable floor and then bounces up once we cross singularity. (I'm not an "identity freak" BTW.)

Comment author: lukstafi 12 November 2012 11:47:00PM 0 points [-]

To explore some possibilities, have a look at http://www.fanfiction.net/s/5389450/1/The-Finale-of-the-Ultimate-Meta-Mega-Crossover -- where MWI is generalized to what I call "Universal Distribution Metaphysics".

Comment author: Oligopsony 12 November 2012 03:33:23PM 2 points [-]

Aside from all the other reasons for relief offered in this thread, the fact that you're not in Quantum Hell right now is anthropic evidence that QI isn't true in the sense you should be worried about.

(You may note that this is a generalized argument against most possible forms of immortality.)

Comment author: tim 10 November 2012 04:44:12AM *  3 points [-]

What makes you privilege the experience of dying over other, more positive experiences? That is, even if there's a very large number of branches where we experience this suffering, wouldn't there also be very large numbers of a branches containing positive experiences? It's the ratio of positive to negative experiences that matter, not the raw quantity of one or the other.

ETA: That is to say, the reasoning "when I'm close to dead, no matter how likely I am to die in the next instant, at least one branch of me continues on suffering" is symmetric to "man this hot shower is amazing, good thing there at least one branch of me that continues to enjoy it indefinitely."

Comment author: Furcas 10 November 2012 04:53:31AM *  1 point [-]

Well, if I didn't know about MWI, I would believe it to be much more likely that I'll die (in some number of years) than that I'll become a happy immortal.

Since I do know about MWI, this translates into a really high Quantum Torment/Quantum Happiness ratio.

ETA a response to your ETA: I don't think it's symmetric. There's a next moment for your consciousness whether or not you stay in the hot shower, but there is only a next moment for the consciousness of a dying and suffering person if he keeps living (and most likely suffering). That's the whole point.

Comment author: tim 10 November 2012 05:06:15AM 1 point [-]

But your (main) concern doesn't seem to be death per se, rather the possibility of existing for an extremely long time in the state of almost-being-dead. It is not at all obvious to me why such a possibility carries more weight than the possibility of existing for an extremely long time in the state of being perfectly healthy. In fact it seems like most observer moments over all branches would be biased toward a state of health rather than illness.

Comment author: Furcas 10 November 2012 05:33:59AM 0 points [-]

As I alluded to in my ETA above, the whole point of quantum immortality is that we'll end up in a really unlikely branch because we won't exist in all the other branches.

Are you asking why, once I'm in a state of almost-being-dead, it's likely that the branch I'll be in at the next moment will be one in which I'm still almost-dead, rather than healthy? It's because even if MWI is true, the next moment is caused by the current moment. If my body is deteriorating now and nothing happens to change that, it will be deteriorating in a moment too.

Or are you asking why it's more likely I'll end up in a state of almost-being-dead than not in the first place? I've answered that one above.

Comment author: tim 11 November 2012 12:20:59AM 2 points [-]

Hm, I think my confusion is over the idea of quantum immortality in general rather than specific to the torment scenario.

If I understand it correctly, QI says that at some point in time there will exist a single branch containing a "me" that, against all odds, never dies. The idea of quantum torture comes from noting that continuing to exist in a state of right-about-to-die would likely be extremely unpleasant.

So, what makes this single branch so important? Why is the me in that branch more "me" than a me any given branch that exists with temporally concurrence to other branches? For example, there is probably a branch out there where I am existing in horrible agony at this point in time. I don't see why we should worry about the quantum torture branch and not this branch. They both contain "me."

Basically, QI gives more importance to a "me" in a branch that is temporally isolated from "me's" in other branches. I don't see why this is the case or why time should be a factor at all.

Comment author: Decius 12 November 2012 10:24:20PM 0 points [-]

What makes the consciousness of the next moment the same consciousness as this moment?

Comment author: Luke_A_Somers 12 November 2012 02:50:09PM 0 points [-]

Because the subjective observability constraint doesn't cut off cases where the shower ends badly.

Not saying I entirely buy QI - measure clearly means something - but that's how the argument goes.

Comment author: Nominull 10 November 2012 07:27:47AM 3 points [-]

If you're prepared to say you're immortal because even if you die you're still alive in some other branch, it seems like you shouldn't even need quantum mechanics. You're immortal because even if you die, you're still alive in the past.

Comment author: Furcas 10 November 2012 08:18:19AM 4 points [-]

Sure, but the subjective experience of being my past self will never causally follow from my subjective experience of being the current me, so I don't care.

Put another way, you're talking about timeless immortality. I'm talking about real immortality.

Comment author: Nominull 10 November 2012 06:15:00PM 2 points [-]

The difference between "never" and "with order epsilon probability" is of order epsilon, I wouldn't worry your head about it.

And you're not talking about real immortality, that's my point. Quantum immortality is no more real than timeless immortality, and arguably less.

Comment author: Vladimir_Nesov 10 November 2012 01:08:11PM 1 point [-]

Put another way, you're talking about timeless immortality. I'm talking about real immortality.

You're talking about a different notion of immortality. As it ignores probability, it doesn't seem to capture the usual concept very well.

Comment author: wedrifid 11 November 2012 02:50:51AM *  1 point [-]

You're talking about a different notion of immortality. As it ignores probability, it doesn't seem to capture the usual concept very well.

For sure, whatever kind of "immortality" it is it certainly isn't something I would tend to describe as "real"!

Comment author: Eliezer_Yudkowsky 10 November 2012 06:16:14AM 1 point [-]

If you're worried about it, just sign up for cryonics.

Comment author: Furcas 10 November 2012 06:47:35AM *  1 point [-]

If you're worried about it

You mean you're not?

Seriously Eliezer, without you and Max Tegmark I probably wouldn't even take MWI seriously. You gotta help me. :)

just sign up for cryonics.

Okay.

Comment author: Eliezer_Yudkowsky 10 November 2012 06:32:12PM 14 points [-]

You mean you're not?

I'm signed up for cryonics. I'm a bit worried about what happens to everyone else.

Going on the basic anthropic assumption that we're trying to do a sum over conditional probabilities while eliminating Death events to get your anticipated future, then depending on to what degree causal continuity is required for personal identity, once someone's measure gets small enough, you might be able to simulate them and then insert a rescue experience for almost all of their subjective conditional probability. The trouble is if you die via a route that degrades the detail and complexity of your subjective experience before it gets small enough to be rescued, in which case you merge into a lot of other people with dying experiences indistinguishable from yours and only get rescued as a group. Furthermore, anyone with computing power can try to grab a share of your soul and not all of them may be what we would consider "nice", just like if we kindly rescued a Babyeater we wouldn't go on letting them eat babies. As the Doctor observes of this proposition in the Finale of the Ultimate Meta Mega Crossover, "Hell of a scary afterlife you got here, missy."

The only actual recommendations that emerge from this set of assumptions seem to amount to:

1) Sign up for cryonics. All of your subjective future will continue into quantum worlds that care enough to revive you, without regard for worlds where the cryonics organization went bankrupt or there was a nuclear war.

2) If you can't be suspended, try to die only by routes that kill you very quickly with certainty, or (this is possibly better) kill almost all of your measure over a continuous period without degrading your processing power. In other words, the ideal disease has a quantum 50% probability of killing you while you sleep, but has no visible effects when you wake up, and finally kills you with certainty after a couple of months. Your soul's measure will be so small that almost all of its subjective quantity will at this point be in worlds simulated by whatever Tegmark Level IV parties have an interest in your soul, if you believe that's a good thing. If you don't think that's a good thing, try to die only by routes that kill you very quickly with certainty, so that it requires a violation of physical law rather than a quantum improbability to save you.

3) In other words, sign up for cryonics.

Comment author: Furcas 12 November 2012 08:41:03PM 1 point [-]

Thanks Eliezer. I'll let you know when I've signed up, if you're interested.

Comment author: gwern 12 November 2012 10:26:15PM 2 points [-]

Don't forget to claim your Hanson hour, either.

Comment author: ciphergoth 15 November 2012 02:43:26PM 0 points [-]

I keep remembering mine but am totally daunted by the prospect of claiming it. I feel like I should have some really good stuff lined up to ask about first.

Comment author: gwern 15 November 2012 05:12:12PM 0 points [-]

You could always sell it.

Comment author: ciphergoth 15 November 2012 06:37:45PM 0 points [-]

No, it's precisely because I want to use it a lot that I don't use it :)

Anyway, Robin might reasonably feel that all other things being equal, he prefers to spend time talking to the sort of person who does sign up than the sort of person who doesn't.

Comment author: gwern 15 November 2012 07:02:40PM 2 points [-]

Robin was the one who suggested selling it in his original post http://www.overcomingbias.com/2009/03/my-cryonics-hour.html (and I think most people would not have thought of selling at all), so apparently he disagrees - talking to a person who would pay for an hour of conversation may also be interesting.

Comment author: FeepingCreature 25 July 2016 08:04:41AM 0 points [-]

"Hell of a scary afterlife you got here, missy."

! ! !

Be honest. Are you prescient? And are you using your eldritch powers to troll us?

Comment author: Eitan_Zohar 08 July 2015 06:14:32PM *  0 points [-]

Sign up for cryonics. All of your subjective future will continue into quantum worlds that care enough to revive you, without regard for worlds where the cryonics organization went bankrupt or there was a nuclear war.

Doesn't this mean that you should deliberately avoid finding out whether cryonics can actually preserve your information in a retrievable way, because if it can't it would eliminate the vast majority of the worlds that would have brought you back? Whereas if you don't know it remains undetermined. Am I getting this right?

Comment author: Eliezer_Yudkowsky 14 July 2015 06:35:16PM 2 points [-]

You're confusing subjective probability and objective quantum measure. If you flip a quantum coin, half your measure goes to worlds where it comes up heads and half goes to where it comes up tails. This is an objective fact, and we know it solidly. If you don't know whether cryonics works, you're probably still already localized by your memories and sensory information to either worlds where it works or worlds where it doesn't; all or nothing, even if you're ignorant of which.

Comment author: Eitan_Zohar 15 July 2015 04:52:30AM *  -1 points [-]

How far do "memories and sensory information" extend? I'm worried about what happens during sleep. It's been argued that dreams are a stability mechanism that prevent self-change, but I don't know if that applies to the external world.

Following this line of argument, our memories could change while we are awake if we aren't actively remembering them.

Comment author: Dorikka 10 November 2012 06:23:36PM 1 point [-]

I'm afraid that I don't understand. Can you (or someone else) explain?

Comment author: Eliezer_Yudkowsky 10 November 2012 10:54:53PM 3 points [-]

If you sign up for cryonics, your "last" moments should have causal continuity with a much larger measure of futures than the QTI ones, so it should be prophylactic against quantum immortality. I hope.

Comment author: pragmatist 10 November 2012 07:21:00AM *  1 point [-]

Quantum immortality as you describe it is not a consequence of MWI. It's not true that every single change in an MWI universe is accompanied by branching. Branching occurs when microscopic quantum superpositions decohere, i.e. when interactions magnify microscopic superpositions into macroscopic superpositions. So branching is the consequence of a particular type of physical process: the "measurement" of a microscopic superposition by its macroscopic environment. Not all physical processes are of this type, and its not at all obvious to me that the sorts of processes usually involved in our deaths are of this sort. When someone gets run over by a bus, for example, what we're dealing with is an already decohered macroscopic system (the bus) interacting with another decohered macroscopic system (the unfortunate victim). We're not dealing with a microscopic superposition getting kicked up to the macroscopic scale. Now it may be the case that the actual processes that go on in the victim's brain after the accident and determine whether she dies or not are "measurement"-type processes, but I'd need to hear an argument that this is usually the case.

Even if one's death can be directly attributed to a measurement-type event, quantum immortality doesn't follow. Say a person gets cancer from a single radiation event (not sure if this is possible, but I'm postulating that it is), and subsequently dies from this cancer. The radiation event is a microscopic quantum process, and his body acts as a macroscopic detector. In this case, one would get branching. One one branch he would get cancer and eventually die from it. On the other he wouldn't get it. But even on the branch in which he dies, death is not instantaneous. He experiences both branches, not just the one in which he lives longer. So this is not a quantum immortality type situation.

One might be able to set up an artificial situation in which quantum immortality is real, but it would have to be a very carefully constructed scenario, one in which the moment of death coincides with the moment of decoherence (of course, neither of these are literal moments). I don't think the circumstances under which most of us die are of this sort.

Comment author: Furcas 10 November 2012 08:27:53AM 2 points [-]

Okay, this is the kind of argument that, if true and correct, would actually convince me that quantum torment is not real.

My extremely limited, incomplete, and non-mathy understanding of QM makes me suspicious of your explanation because it talks about things like macroscopic measurements affecting the fundamental level of reality, and about fundamental events only happening sometimes in special circumstances.

But since my understanding is so incomplete, I don't actually trust it. I'll have to rely on other people who understand QM, or give Eliezer's sequence and my physics books another shot! Since this has become such an important topic to me, I don't think I have a choice anymore, anyway.

Thanks for the reply.

Comment author: pragmatist 10 November 2012 08:37:06AM *  3 points [-]

My extremely limited, incomplete, and non-mathy understanding of QM makes me suspicious of your explanation because it talks about things like macroscopic measurements affecting the fundamental level of reality, and about fundamental events only happening sometimes in special circumstances.

World-splitting in MWI is not a fundamental event. "Worlds" themselves aren't fundamental objects in the theory. They are imprecisely defined macroscopic entities that emerge from decoherence. So nothing I say involves macroscopic processes affecting the fundamental level of reality.

ETA: Perhaps you're thrown off by my use of the word "measurement" because it suggests something vaguely Copenhagish. All I mean by a measurement-type interaction is an interaction between the system and its environment that leads to einselection.

Comment author: pragmatist 10 November 2012 03:43:45PM 1 point [-]

Hmmm... this post has received at least three downvotes at this point. I'm pretty confident that everything I've said here about the MWI is correct, but if someone thinks it isn't, I'm very interested to hear why. So if the downvoting is attributable to perceived factual inaccuracy, could you let me know what you think the inaccuracy is? Thanks.

Comment author: The_Duck 11 November 2012 01:54:13AM 2 points [-]

I have an objection to this:

So branching is the consequence of a particular type of physical process: the "measurement" of a microscopic superposition by its macroscopic environment. Not all physical processes are of this type, and its not at all obvious to me that the sorts of processes usually involved in our deaths are of this sort.

I think that essentially all processes involving macroscopic objects are of this type. My understanding is that the wave function of a macroscopic system at nonzero temperature is constantly fissioning into vastly huge numbers of decoherent sub-regions, i.e., "worlds." These worlds start out similar to each other, but we should expect differences to amplify over time. And, of course, each new world immediately begins fissioning into vast numbers of "sub-worlds."

So, while in one world you might get run over by a bus, there is e.g. another world that separated from that one a year ago in which the bus is late and you survive. Plus huge numbers of other possibilities.

In this vast profusion of different worlds, for any given death there's essentially always another branch in which that death was averted.

Comment author: Armok_GoB 11 November 2012 07:43:10PM 1 point [-]

And then there's the branch with extremely small amplitude that separated 30 seconds ago where the bus explodes form proton decay.

Comment author: Oscar_Cunningham 10 November 2012 06:01:01PM 0 points [-]

I don't think you have any factual inaccuracies.

Comment author: wedrifid 11 November 2012 03:29:47AM 1 point [-]

I don't think you have any factual inaccuracies.

Most of his premises are approximately correct but applied incorrectly to reach an incorrect conclusion (that is the first sentence). It could be restored by injecting caveats like "for all practical purposes" and "virtually" here but the thing is the whole "Immortality" notion is already ridiculously impractical to begin with. Quantum tunneling through the bus and leaving your arm behind is only a few gagillion orders of magnitude more unlikely than winning Quantum Roulette ten times a day every day for 1,000 years. It is stupid to consider those improbable outcomes as privileged but not wrong.

Comment author: philh 10 November 2012 09:02:08PM 1 point [-]

All conscious beings should expect to experience the next moment in at least one Everett branch even if they stop existing in all other branches, and the moment after that in at least one other branch, and so on forever.

I don't think this is quite true. Rather, if there is precisely one Everett branch in which a conscious being still exists, they should expect to experience it. If there is no such Everett branch, the conscious being will still be conscious in this moment but will not experience any future moments. If there are multiple, the conscious being should expect to experience one of them.

Comment author: Armok_GoB 10 November 2012 08:23:33PM 1 point [-]

Since others have already covered the physics side of things:

Your problem here is mostly with using confused notions of things like "conciousness", "real", "expect" and "self". As you level up starts grokking thinking in terms of the measure of computations across the tegmark multiverse and the like, these kind of problems will naturally dissolve. (and be replaced by new arguably much worse unrelated ones)

Comment author: Conscience 14 April 2016 12:14:22PM 0 points [-]

In thought experiment (https://en.wikipedia.org/wiki/Quantum_suicide_and_immortality) it says: "Barring life after death, it is not possible for the experimenter to experience having been killed, thus the only possible experience is one of having survived every iteration". QM IMHO does not say about afterlife, so afterlife takes care of Quantum Torment.

Comment author: Heighn 05 March 2014 07:11:45PM *  0 points [-]

I was thinking about this post and thought up the following experiment. Suppose, by some quantum mechanism, Bob has a 50% probability of falling asleep for the next 8 hours and a 50% probability of staying awake for the next 8 hours. By the same logic as QI, should Bob expect (with 100% certainty) to be awake after 2 hours, since he cannot observe himself being asleep? I would say no. But then, doesn't QI fail as a result?

Comment author: IlyaShpitser 11 November 2012 03:46:30AM 0 points [-]

I don't know much about quantum mechanics, so

http://www.smbc-comics.com/?id=2475

Comment author: Giles 10 November 2012 07:10:50PM *  0 points [-]

It sounds like this is a question that you really, truly need to know the correct answer to because you have something to protect. I can sympathise here, because my own journey into rationalism really started when I realised that something extremely bad might happen - something so important that I needed to be sane about it.

When faced with a question that you need the correct answer to, there's some agreement on LW that the right attitude is one of curiosity. Having too much fear can get in the way of clear thinking - and you'll need a lot of clear thinking here because even established philosophers struggle with these kinds of topic. You just need to get better at it than they are. But my advice is that the more immediate project is to try and move yourself from a position of terror to one of curiosity.

(Feeling like you're doing the most sensible thing might also help with the terror, I'm not sure).

I don't know whether it's best to try and ramp up curiosity on the quantum immortality topic or whether it would be better to approach related topics first. UDT, the anthropic principle and possibly infinite ethics are all very relevant (and active) areas of research.

Anyway, you're welcome to PM me, either about any of the topics I've mentioned (I've thought about them a bunch but I shouldn't be considered an expert), or on the meta-problem of how to get less terrified and more curious.