Quantum Immortality without MWI?

[entropy1]

And that exposes a weakness of MWI, namely that you are certain to get beyond 200 years old. However, at the price of dying astronomically more often.

No, the MWI does not say this. The MWI does not say people don't age, or don't die of old age. The MWI only says that, if a particular event which might or might not kill you depends on quantum uncertainty, there will be a branch where you live and a branch where you die. But it is highly unlikely that all potentially fatal events that happen to people as they age depend on quantum uncertainty. If there is no quantum uncertainty about an event, and it is fatal, there is no branching according to the MWI; you just die.

Perhaps I should expand on this a little more. Many people seem to assume that the MWI means anything at all that they can imagine will occur in some branch. You seem to be assuming that, since you can imagine that a human could live to be 200 years old, there must be some branch in the MWI in which that occurs. But that assumption is not valid. The MWI does not guarantee that any outcome you can imagine will have a nonzero amplitude in the wave function (which is what is required for there to be some branch in the MWI in which it occurs). If you want to say that there will be a branch in which some outcome occurs, you have to actually make an argument for why there should be a nonzero amplitude for that outcome in the wave function. You can't just assume it.

Yes, I think then I was wrong about that and that I misunderstood the people I based my opinion on. I do not think I was assuming anything. I just misunderstood.

However, the probability of getting beyond 200 years old are (necessarily) equally improbable.

So aren't we in the same ballpark? (Meaning that is remains improbable to get to live to be two hundred) It occurs to me you are often saying "No" and then agreeing with me in some way. I must say I experience communication problems in my life and here we also have a language problem, and then of course the lack of knowledge on my side, which is why I am here. I confess I often act as if I know something while I am really not sure (at my peril of course). I should not continue doing that. This forum is the best forum about physics, so I need to stay here, but I intent to do know my limitations. So since this is not the chat area, I keep it with this.

 

[Jarvis323]

Yes, I think then I was wrong about that and that I misunderstood the people I based my opinion on. I do not think I was assuming anything. I just misunderstood.

So aren't we in the same ballpark? (Meaning that is remains improbable to get to live to be two hundred) It occurs to me you are often saying "No" and then agreeing with me in some way. I must say I experience communication problems in my life and here we also have a language problem, and then of course the lack of knowledge on my side, which is why I am here. I confess I often act as if I know something while I am really not sure (at my peril of course). I should not continue doing that. This forum is the best forum about physics, so I need to stay here, but I intent to do know my limitations. So since this is not the chat area, I keep it with this.

In the case of 200, that seems like a pretty easy number to reach for some branch in this day and age. It would hardly be surprising if within our life times, the technology to achieve that and more arrives, so that you or me could break that barrier with no branching required.

I would disagree with an argument that addressing the question of aging and MWI isn't a matter of physics. Biology is physical. Aging can be studied scientifically. We can do things like estimate the probability of damage to dna through mutation, cancer cells forming, damage from free radicals, etc. We can also study the dynamics involved in these things and the sensitives to initial conditions. We can make assumptions about how quantum uncertainty influences those initial conditions. A few assumptions later, we have some arguments that we can make using what we know about biology and dynamics, and randomness, and MWI, about whether someone is likely to reach 200 in some branch.

Whether the possible development of technology in some branch to make it happen can be supported with physics based arguments, I don't know. When we are as advanced as we are now, and rapidly experiencing breakthroughs, it wouldn't be surprising that there would be diverging histories in different branches, so that one might be a little ahead technologically than another, and if that is all it would take.

We are talking about a lot of histories here. And chaos means they likely diverge a lot. That means that we likely would have a whole lot of different histories. And the same type arguments made by Tegmark (effective randomness, ergodicity, chaos and mixing) apply as reasons to think that the space of histories we think are possible classically would be covered pretty well.

The valid point being made by Peter is that (assuming MWI) we cannot prove that it would happen. Also, we can't prove that dark matter exists, or that the universe is expanding, etc. There still may be strong evidence that someone can present as part of an argument in favor of quantum immortality given MWI.

Though physics at this level is inherently speculative and presumptuous, people can still publish papers about it. And PF supports discussion of such publications.

But at PF it's also against the rules to partake in such speculation yourself. In that sense, Peter is OK to claim that reaching 200 isn't provably guaranteed to occur in some branch, and end it there. So to further the discussion, maybe you need to find a peer reviewed paper making an argument in favor of quantum immortality. It shouldn't be too difficult to find such an argument in a peer reviewed paper. Then we voice our support for different arguments, and try to spot problems with others, and we can ultimately, subjectively pick which ones we agree with more individually.

 

[akvadrako]

So to further the discussion, maybe you need to find a peer reviewed paper making an argument in favor of quantum immortality. It shouldn't be too difficult to find such an argument in a peer reviewed paper.

It is quite difficult, actually. The Wikipedia article is nearly a complete review of the research out there and it isn't much. The most supportive paper is probably David Lewis' How Many Lives Has Schrödinger's Cat?. He argued MWI leads to QI, but he also thought MWI was wrong.

There are also few papers arguing against it.

 

[Jarvis323]

It is quite difficult, actually. The Wikipedia article is nearly a complete review of the research out there and it isn't much. The most supportive paper is probably David Lewis' How Many Lives Has Schrödinger's Cat?. He argued MWI leads to QI, but he also thought MWI was wrong.

There are also few papers arguing against it.

Actually, it looks like QI is not what I though it was. The thread has mostly been about just a version of you (presumably one with a common parent in the tree) survives for 200 years, or indefinitely. It looks like QI also concerns the concept of what makes you, you, and the soul, and everything. And it looks like it has become a contentious point whether MWI absolutely implies QI.

 

[Demystifier]

This assumes that such a fluctuation wouldn't also alter the structure of a human body to the point where it could not support life. I see no reason to believe this

The great majority of such fluctuations would not support life. But one very very small fraction of them will support life. In MWI it doesn't matter how small that fraction is, as long as it is not strictly zero.

 

[Physicuser]

Maybe I didn't understand well previous objections, but it seems that assuming physicalism, and an infinite universe in space or time, if Leibniz' Principle of the Identity of Indiscernibles is true and apply to conciousness (and then, a person exactly like you is you) and the Infinite Monkeys Theorem is true, if it is physically possible reach 200 years old, one way or another, you will do it.

But in this case, it's not necessary a physical continuity, since a random Boltzmann Brainexactly like you at 200 years old is you too, indistinguishable from an "evolutionary" you, and so a 300, 400, etc.

However, as I said in a previous post, in this case I guess the number of observer-moments above the natural life span would be bigger than the normal ones, so it will be more probable for you being experiencing one of them.

 

[Physicuser]

The thread has mostly been about just a version of you (presumably one with a common parent in the tree) survives for 200 years, or indefinitely.

But assuming physicalism and the identity of indiscernibles (I am not sure if mainstream theories on conciousness do it), it's not about a different version of you surviving: from a subjective perspective, you are the version who will survive.

I mean, there are, right now, infinite persons like you, all of them are "you", only became different people when they diverge and experience different things. Then, an infinite number of them will follow the same future path "you" does. At the moment of death, the vast majority of them will die, but some survive, since you can't experience nothingness, this is not a divergence, just physical observers disappearing, not a different observer-moment, so you will experience survival.

As I am understanding it right now, it's not that there are, for example, 1000 "yous", 999 will die an 1 survive, and you can't tell if you are the one who will survive or not, but the 1000 physical beings are only one and the same person, experiencing exactly the same and never diverge, so, subjectively, YOU are the one who will survive. And for this you don't need MWI, just the physical possibility of surviving and an infinite universe (if it's true that all possible happens with infinite time/space).This reasoning could be flawed (and I hope it to be flawed), but I am unable to see why.

 

[Physicuser]

It is quite difficult, actually. The Wikipedia article is nearly a complete review of the research out there and it isn't much

There are some papers on Subjective Immortality (not only Quantum, but involving infinite universes, Boltmann Brains, etc.), I think they are not peer-reviewed, but from my layman's vision the reasonings seems plausible.

Here they are, if somebody more expert wants to read them and tell us his opinion:

- Necessary conditions for Quantum Immortality
- https://www.researchgate.net/publication/308958767_Boltzmannian_Immortality

In this blog one of the autors talk about it:
https://www.lesswrong.com/posts/zh2vWuhgCRQN6M7AY/the-map-of-quantum-big-world-immortality.

 

[PeterDonis]

That is the way QI likely works though

I don't see any advocates of QI talking about how human technological innovations are going to increase the human lifespan. That's why I specifically excluded that possibility in my previous posts.

If we want to talk about possibilities for human technological innovations increasing the human lifespan, then of course there are many of them and it is extremely likely that, even if such things never get discovered in our Hubble volume, they will be discovered in some Hubble volume. But none of that reasoning depends on invoking astronomically improbable events and waving one's hands and saying they will make a person immortal but still leave them functioning just fine in all other respects.

 

[PeterDonis]

The great majority of such fluctuations would not support life. But one very very small fraction of them will support life.

Sorry, but I don't buy this claim, because it's just a bare assertion. Write down a plausible wave function and unitary evolution that shows this and I might pay attention. But no advocate of quantum immortality has ever done that. They just wave their hands and assert it. That's not a valid argument in my book.

 

[PeterDonis]

if it is physically possible reach 200 years old

Remember that I excluded human technological innovation in my previous posts, since that's what advocates of quantum immortality appear to me to be doing. It's one thing to say it's physically possible; it's quite another thing to say that there are chains of physical possibility that do not involve human technological innovation. The latter, much stronger claim is the one QI advocates appear to me to be making, and I don't think it's valid.

 

[PeterDonis]

I mean, there are, right now, infinite persons like you, all of them are "you", only became different people when they diverge and experience different things.

Then you are redefining "you". Instead of meaning "a unique full sequence of human experiences, however long it lasts", you are defining it to mean "a sequence of human experiences that is just like yours up to now, but can diverge afterwards". Which means there are an infinite number of different "yous" that just happen to share the same experiences up to a certain point. But then these "yous" are no longer indiscernible, and your invocation of Leibniz's identity of indiscernibles is wrong. Identity of indiscernibles only applies if the two things are exactly indiscernible, in their totality; it doesn't mean identity of things that are only indiscernible up to a certain point.

 

[Physicuser]

Then you are redefining "you". Instead of meaning "a unique full sequence of human experiences, however long it lasts", you are defining it to mean "a sequence of human experiences that is just like yours up to now, but can diverge afterwards". Which means there are an infinite number of different "yous" that just happen to share the same experiences up to a certain point. But then these "yous" are no longer indiscernible, and your invocation of Leibniz's identity of indiscernibles is wrong. Identity of indiscernibles only applies if the two things are exactly indiscernible, in their totality; it doesn't mean identity of things that are only indiscernible up to a certain point.

Yes, but if they are indiscernibles at the point of your death, and dying is not a divergence, because you won't experience a different things, just ceased to experience, the one who survive is indiscernible from the others (subjectively), so you are the same, so you are the one who survive, I guess (maybe I'm wrong).

 

[PeroK]

There are some papers on Subjective Immortality (not only Quantum, but involving infinite universes, Boltmann Brains, etc.), I think they are not peer-reviewed, but from my layman's vision the reasonings seems plausible.

Here they are, if somebody more expert wants to read them and tell us his opinion:

- Necessary conditions for Quantum Immortality
- https://www.researchgate.net/publication/308958767_Boltzmannian_Immortality

In this blog one of the autors talk about it:
https://www.lesswrong.com/posts/zh2vWuhgCRQN6M7AY/the-map-of-quantum-big-world-immortality.

There is a potential issue which is that to apply probability theory to something you effectively have to understand it completely. Unless and until you have tested MWI and established the probabilities, you have a significant IF about anything you conclude. And if, hypothetically, you could test out MWI in some way, who knows what you would find.

Another issue is the physical interpretation of an infinite experiment machine (this is my own terminology). Any experiment we can conduct is finite. You can run an experiment with ##N## possible outcomes ##m## times. You can't ever have run an experiment an infinite number of times. And, any experiment can only have a finite number of oucomes. You can sort of push it to a countable number, but (IMHO) only if you allow some unphysical assumptions - like always being able to do something faster and faster, or allowing unlimited time.

Theories based on an infinite universe or an infinite branching of the wave-function on the face of it do allow nature to do an infinite number of things. In other words, nature becomes an infinite experiment machine.

I'm not sure how to interpret that physically and what meaning can be given to the outcome of an experiment that has been conducted an infinite number of times. Perhaps that makes physical sense and perhaps it doesn't - and, it's not clear how we could ever "observe" such a thing, as we can only process a finite amount of information in any case.

That's my reservation anyway about all these things that rely on physically achieving an infinite number of outcomes.

PS If the MWI branching is finite, then you are back in the realm of finite experimental outcomes and the paradoxes like QI should go away!

 

[PeterDonis]

if they are indiscernibles at the point of your death, and dying is not a divergence, because you won't experience a different things, just ceased to experience

"Ceased to experience" doesn't mean "ceased to exist". In a branch where you die, your dead body is still there, and still discernible from the live body in the other branch. So no, dying is a divergence. Experience is part of what exists, but not all of it; and indiscernibility has to take into account all of what exists.

 

[akvadrako]

I don't see any advocates of QI talking about how human technological innovations are going to increase the human lifespan. That's why I specifically excluded that possibility in my previous posts.

Who are these advocates of QI? The only significant scientist I know of who seemed to give it credence was Everett, and that's only because of one second hand quote in a biography.

I do agree that what some people claim doesn't seem likely. Like David Lewis, who thought that you'll age normally then somehow escape death at the last moment.

The part about QI that does make sense (at least given the assumptions) is to say, at point X in the future, there will be some future versions of me in worlds that still exist and other worlds where I don't exist at all. And when X is 200 years, most of those surviving worlds will happen because of advances in technology.

 

[PeterDonis]

Who are these advocates of QI?

The ones discussed in the Wikipedia article linked to in the OP of this thread. (David Lewis, whom you mention, is one of them.)

 

[akvadrako]

The ones discussed in the Wikipedia article linked to in the OP of this thread. (David Lewis, whom you mention, is one of them.)

I think, based on discussions on that wiki talk page, that there are only two camps besides Everett. There are those that don't think MWI is real and those that don't think it implies QI. So there are not really advocates in the sense of people writing papers about how it would plausibly work.

 

[Physicuser]

"Ceased to experience" doesn't mean "ceased to exist". In a branch where you die, your dead body is still there, and still discernible from the live body in the other branch. So no, dying is a divergence. Experience is part of what exists, but not all of it; and indiscernibility has to take into account all of what exists.

That could be the fundamental question, and I am not sure... Objectively you die, but subjectively you are what you experience, so I don't know...
If the Principle of Indiscernibles is true, then, the next-second you and a Boltzmann Brain identical to him are the same person. And then, wouldn't this apply to a Boltzmann Brain experiencing having survived your death, so, from a subjective point of view, the same as if you had survived?

 

[PeterDonis]

If the Principle of Indiscernibles is true, then, the next-second you and a Boltzmann Brain identical to him are the same person.

No, they aren't, because a "person" is not a snapshot at one instant of time. A "person", as I have already described in previous posts, is a full sequence of experiences throughout an entire lifetime. A Boltzmann Brain is not. These two things are easily distinguishable.

 

[PeterDonis]

Objectively you die, but subjectively you are what you experience

We are talking about physics here, not philosophy or psychology. Yes, your physical body can no longer support having subjective, conscious experiences when you die. But your physical body is still a physical thing. It doesn't just stop existing if you stop having conscious experiences with it.

 

[Physicuser]

Despite some interesting remarks, unfortunately, it seems to me that some kind of Subjective Immortality is probably true, let's summarise and debate if there are flaws and try to debunk it.

I think, essentially this is required:

- Possiblity: it's possible to live indefinitely. There are some ways this could happen, not only through quantum miracles that keep you barely alive (Quantum Immortality), but medical advancement in life extension, crionics, or if physical continuity is not needed, Brain in a vat, Boltzmann brains, or Digital simulations (if this is possible)

- Infinites: the Infinite Monkeys Theorem, and the Poincaré Recurrence Theorem. All possible happens in an infinite universe. With current knowledge, the universe is most probable infinite in some way: if its shape is flat or hyperbolic, is infinite in space, and probably in time (Random fluctuations after the Heat Death, leading eventually to another Big Bang, or just infinites Boltzmann Brains); if spherical, it will collapse and probably, bounce again; if a 3-thorus, its cyclical... Even if it is finite, small and don't last forever, several mainstream theories imply a big or infinite multiverse (String Theory, MWI, Mathematical Universe...).

- Identity: the Principle of Identity of Indiscernibles. Conciousness is nothing special or unique, a person/brain exactly like you is you and have the same "conciousness".

So, if there are infinite "yous", and the universe is infinite, happening all possible, one way or another, one future version of you will survive, and he will be "you" with respect to "this-you" (and then, don't make sense ask who of them you will be, you are all, since they are different with respect each other, but not with you now).Objections:
- These means of immortality could fail: it's not clear if quantum effects can prevent death, if crionics works, if it's possible to simulate a person, etc.
- Infinite space/time does not necessarily imply that all possible happens.
- Conciousness and mind are not well known, it's not sure if the Principle of Identity applies to it, if another "you" is you, if it is required continuity of the body or experience, etc.

Let's see if this can be refuted.

 

[PeterDonis]

it's possible to live indefinitely

Physically, I think this is true, yes. I personally don't think it's possible by the "quantum miracle" route (because I don't think such "miracles" are actually possible), but it should be by technological advancement.

if physical continuity is not needed

I don't think this makes sense. A person is not a single snapshot at an instant of time. A person is a coherent sequence of experiences over a length of time. That requires physical continuity (although quite possibly not physical continuity in the sense of having a human brain like the ones we have now through the entire sequence of your personal experiences--technological advancement might make it possible to keep physical continuity of experience while changing the underlying substrate to something more reliable and less error prone than the current human brain).

All possible happens in an infinite universe.

Yes. This is one of the basic points of the Tegmark paper.

Conciousness is nothing special or unique, a person/brain exactly like you is you and have the same "conciousness".

This is true as long as you recognize how extremely strong the "exactly like" condition is. It requires the exact same entire sequence of experiences, which means the exact same entire sequence of physical events down to whatever level is required to ensure an identical sequence of experiences.

To put this another way: if it is possible for technological advancement to produce a future-infinite sequence of experiences that starts with the exact sequence of experiences that you have had up to now, then somewhere in the infinite multiverse there will be such a future-infinite sequence of experiences--a person who shares all of the experiences of "you" up to now. But that does not mean that you--the person here on Earth who is reading this post right now--are that person. The fact that there is some future-infinite sequence of physical events that instantiates a person whose experiences up to whatever age you are now are exactly the same as the ones you have had up to now, does not mean the sequence of physical events that underlie your experience here on Earth is such a future-infinite sequence.

In other words, even if there is an immortal person somewhere in the infinite multiverse who shares all of your experiences up to now, you don't know if that person is you, because "you" does not just mean the sequence of your experiences up to now: it means the entire sequence of experiences that the sequence of your experiences up to now, here on Earth, at this location in the multiverse, is the start of. And you don't know whether that sequence of experiences will be future-infinite or not. Nothing in Tegmark's paper or the Quantum Immortality literature can tell you that.

 

[Jarvis323]

Despite some interesting remarks, unfortunately, it seems to me that some kind of Subjective Immortality is probably true, let's summarise and debate if there are flaws and try to debunk it.

I think, essentially this is required:

- Possiblity: it's possible to live indefinitely. There are some ways this could happen, not only through quantum miracles that keep you barely alive (Quantum Immortality), but medical advancement in life extension, crionics, or if physical continuity is not needed, Brain in a vat, Boltzmann brains, or Digital simulations (if this is possible)

- Infinites: the Infinite Monkeys Theorem, and the Poincaré Recurrence Theorem. All possible happens in an infinite universe. With current knowledge, the universe is most probable infinite in some way: if its shape is flat or hyperbolic, is infinite in space, and probably in time (Random fluctuations after the Heat Death, leading eventually to another Big Bang, or just infinites Boltzmann Brains); if spherical, it will collapse and probably, bounce again; if a 3-thorus, its cyclical... Even if it is finite, small and don't last forever, several mainstream theories imply a big or infinite multiverse (String Theory, MWI, Mathematical Universe...).

- Identity: the Principle of Identity of Indiscernibles. Conciousness is nothing special or unique, a person/brain exactly like you is you and have the same "conciousness".

So, if there are infinite "yous", and the universe is infinite, happening all possible, one way or another, one future version of you will survive, and he will be "you" with respect to "this-you" (and then, don't make sense ask who of them you will be, you are all, since they are different with respect each other, but not with you now).Objections:
- These means of immortality could fail: it's not clear if quantum effects can prevent death, if crionics works, if it's possible to simulate a person, etc.
- Infinite space/time does not necessarily imply that all possible happens.
- Conciousness and mind are not well known, it's not sure if the Principle of Identity applies to it, if another "you" is you, if it is required continuity of the body or experience, etc.

Let's see if this can be refuted.

Here are some of my thoughts.

If you make the assumption that people are discrete and identified only by their discrete properties, then you don't necessarily have a model of consciousness that defines humans as conscious, but not rocks, or any discrete objects. So let's just simplify the problem to that of a rock. Maybe over time, it erodes, gets chipped at, things get cemented to it, maybe eventually it turns to sand, gets scattered around and mixed with other things, goes into a black hole. Where do we draw the line at it still being something that we can call an object that was that rock? If we say, after it splits in half, then we have to reconcile with the fact that you have also shed matter through time. Then there would be hardly any objectively defined continuation of you. Each iteration is someone else. If we say never, then you just need conservation of energy for you to go on forever as this you, even if that you has turned into gamma-rays.

If we include a definition of alive. Then we can say there are the yous that goes on forever, as energy, and there are the yous that live forever. But the you-ness we've defined doesn't distinguish the living you from the dead you. They are either both you or neither is.

If it's by assumption in the first place that we guarantee the discrete you will go on in a living form, then I guess that's all there is to say about an indefinitely surviving/living branch. It will be you as much as any other branch is you, including those that have long since mixed back into the environment.

So I guess in my opinion, it would be more interesting if there were some more special definition of consciousness and youness.

 

[PeterDonis]

it would be more interesting if there were some more special definition of consciousness and youness

This is the same general point I was trying to get at in the latter part of post #58, about how strong the "exactly like" condition is.

 

[votingmachine]

...

If the universe is infinite in space or time, or there are an infinite number of universes like ours (several mainstream theories imply it), is supposed that all possible happens, so there are infinite versions of you out there, and some of them will scape death miraculously.

There are different sizes to infinity. For instance is there ever an instance in all those infinities where you enumerate all the decimals of pi?

I am inclined to disbelieve the MW interpretation. But if you take that as a supposition, you cannot just blindly state all things must happen. There are things that cannot happen, like calculating every digit of pi.

This reminds me of the claims that the arrangement of air molecules in a room could be all on the left half, with the right half a vacuum, or some other highly improbable thing. The arrangement is one that can be considered in the infinite number of arrangements of the individual molecules and their individual properties.

Not all infinitely large sets are the same size. The set of Many-Worlds is infinite. But is still much smaller than the set of Imaginary-Many-Worlds (again just imagine calculating the infinite number of irrational numbers to completion). (Is there one with an infinite number of monkeys, all with typewriters, producing Shakespeare's plays flawlessly?)

 

[PeterDonis]

is there ever an instance in all those infinities where you enumerate all the decimals of pi?

If the universe goes on forever, then yes, in principle there would be.

There are things that cannot happen if the universe only exists for a finite time, like calculating every digit of pi.

See the insert in bold in the quote above.

The set of Many-Worlds is infinite. But is still much smaller than the set of Imaginary-Many-Worlds

What is this "set of Imaginary-Many-Worlds"? What physical theory is it based on?

 

[PeroK]

- Infinites: the Infinite Monkeys Theorem,
Let's see if this can be refuted.

The infinite monkey theorem has been refuted. There was a zoo that gave a monkey a typewriter. It typed out a few characters, got bored and defecated on the typewriter. No Shakespeare ever came out.

https://www.theguardian.com/uk/2003/may/09/science.arts

 

[PeroK]

Objections:
- Infinite space/time does not necessarily imply that all possible happens.

Here's an idea. Let's get rid of the monkey and have a typewriter produce the complete works of Shakespeare purely by "quantum fluctuations".

Somewhere in the infinite universe, there must be an old-fashioned typewriter producing the complete works of Shakespeare at normal typing speed purely by quantum fluctuations.

One possible approach to analysing this is to ask what we mean by "happens". In QM we can only say what happens as a result of a measurement. You can't say that an electron "must be somewhere"; you have to say that if you look for the electron you will find it somewhere.

You could apply this principle to some extent to these statements about what happens in an infinite universe: you have to devise an experiment to look for such a typewriter. You can't claim that such a typewriter exists until have a viable experiment to look for one. And, something like "look at the whole universe at once" is not a viable experiment.

And, if we have any sort of ultimate physical constraints on how much we can do in a given time, then we have a maximum finite probability of finding such a typewriter (in the lifetime of the universe). And, of course, that probability would be extremely small (*).

You end up with something like: given the optimal search capability within the laws of physics, the probability of finding a Boltzmann Brain or a "magic" typewriter is ##p##, where ##p## is very small. And, you would intepret that as being the maximum probability that there "is" such a thing. As opposed to concusing that an infinitude of such things "exists", you conclude that the overwhelmingly probability is that none exist in any meaningful experimental sense.

I'd be interested if anyone has explored this idea, as an antedote to the "everything must happen" ideas.

(*) As an example, suppose every atom in the observable universe could be made into a computer that generates 130,000 random characters every Planck time and this ran for the lifetime of the universe. Then, the probability of any of those computers ever randomly producing Hamlet (130,000 characters) is still almost zero. So, there appear to be basic practicalities in even simulating these rare events. In other words, you run the best simulation of the universe that you can and ask: did a Bolzmann Brain evolve. The answer is not only "no", but that nothing evolved that was remarkable in any macroscopic sense.

 

[Jarvis323]

If MWI is correct, I could set up a machine that generates binary strings based on quantum fluctuations, and interpret them as ASCII. Just by having done that, it would mean that some branches of me would watch the machine print out Hamlet on repeat over and over. Another would see complete proofs of long standing problems in mathematics. Others would see blueprints for advanced technologies. Some would see this exact thread. Some would see detailed instructions on how to develop the most advanced possible technology that could be developed to extend a persons life. Others would see messages telling to go and get lotto tickets with the winning numbers. One would appear to think they were you, and know things only you would know, and appear to be able to communicate with you.

I guess if you really want some "you" to do all of these things and more, and you believe in MWI, then you might want to set such a device up and watch it for a while.

 

[akvadrako]

This is true as long as you recognize how extremely strong the "exactly like" condition is. It requires the exact same entire sequence of experiences, which means the exact same entire sequence of physical events down to whatever level is required to ensure an identical sequence of experiences.

To put this another way: if it is possible for technological advancement to produce a future-infinite sequence of experiences that starts with the exact sequence of experiences that you have had up to now, then somewhere in the infinite multiverse there will be such a future-infinite sequence of experiences--a person who shares all of the experiences of "you" up to now. But that does not mean that you--the person here on Earth who is reading this post right now--are that person. The fact that there is some future-infinite sequence of physical events that instantiates a person whose experiences up to whatever age you are now are exactly the same as the ones you have had up to now, does not mean the sequence of physical events that underlie your experience here on Earth is such a future-infinite sequence.

I don't think the criteria is that strong and maybe in the next few centuries we'll be able to test it with experiments on AI or maybe even people. We could copy a brain, even a rough copy, and ask if it feels like a continuation of the original. The more essential elements copied and the more similar the body, probably the more it'll feel like the original.

Requiring an exact copy is too much; people are not even exact copies of themselves from moment to moment. Our memories change and our perspectives of them change. If you change someone's body or situation drastically, that's also enough to feel like someone else. Consciousness can also be discontinuous, say if the brain is shutdown for a while due to extreme cold.

I suppose the deeper question is: is there anything more to the expectation of a future experience than the existence (in all of reality) of an entity feeling like it's a future version of you now.

 

[PeroK]

If MWI is correct, I could set up a machine that generates binary strings based on quantum fluctuations, and interpret them as ASCII. Just by having done that, it would mean that some branches of me would watch the machine print out Hamlet on repeat over and over.

Of course you couldn't! That's the point. You have no capacity to process an infinite amount of data. And, the amount of data you need to collate to see Hamlet appear even once involves processing something like ##100^{130,000}## bytes of data, which you cannot do.

 

[entropy1]

Don't we have to be careful invoking infinities? Like the hotel that accommodates an infinite number of guests and that sort? Anything may be possible!

 

[PeroK]

Don't we have to be careful invoking infinities? Like the hotel that accommodates an infinite number of guests and that sort? Anything may be possible!

I agree. Hilbert's Hotel is well-defined mathematically, but it's at least unclear whether one could ever be built, and it may be physically impossible. Until such time as someone can give a plausible argument for how one might build Hilbert's Hotel, then it's meaningless to talk about it as something physical.

It's not enough, IMHO, to wave your arms and say "infinite universe" or "MWI". If someone says that somewhere in Hilbert's Hotel there is a monkey who has just randomly typed Hamlet, then that's a physically meaningless statement, IMO.

If you have a computer in every room that produces 130,000 characters at random, then mathematically there are an infinite number of rooms where those characters are precisely the full play Hamlet. That's a mathematical result that is not physically meaningful.

 

[votingmachine]

What is this "set of Imaginary-Many-Worlds"? What physical theory is it based on?

The two things I was thinking on were the sizes of infinite sets and Godel's incompleteness theorem.

The set of irrational numbers is infinite, but larger than the set of rational numbers. There are more irrational numbers than rational numbers, even though there are an infinite amount of both. If there is an infinite amount of time that allows one to conjecture it is sufficient to enumerate the rational numbers, it is insufficient to enumerate the irrational numbers.

Godel's incompleteness theorem is often hand-waved with the idea that one can take the set of all the complete and consistent things that follow from a mathematical system, that set is incomplete. I was doing a similar "hand-waving" statement that the set of all possible universes created by splitting universes at every quantum event (all outcomes happen) leaves out the impossible ones.

So if I consider an atom as a particle in a box, there are allowed solutions and unallowed solutions. Yet I can IMAGINE unallowed ones. I can imagine the electron disappears and never comes back.

That is "Hand-waving". But the underlying principle is still that infinite sets are not all the same size. If one takes the set of all possible "Many-Worlds" it is not definitive that much larger infinite sets are likely. Especially the ones based on wishful thinking.

EDIT: Another hand-wave: MWI is based on a quantum mechanics view of the things happening in the universe. It can never include a universe that is NOT based on quantum mechanics ... or a Newtonian one with faster than light rockets.