Undergrad Quantum Immortality without MWI?

[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.

 

[Physicuser]

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).

I am having troubles with this reasoning. It's seems that if you say "you will win the lottery in 2030", is true, but then this apply too if you say "next second you will tunnel into the moon", but well, you are still here...

 

[PeterDonis]

people are not even exact copies of themselves from moment to moment

You're misunderstanding my definition of a "person". As I have already emphasized, a person is not a snapshot at a single instant of time. A person is an entire sequence of experiences. Obviously for a sequence of experiences to be instantiated by any physical system, the state of that physical system must change from moment to moment. But to think of that as "the person changing" is a misunderstanding. The sequence of physical experiences, instantiated by a physical system that is changing from moment to moment to instantiate those experiences, is the person.

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.

Yes: the question is whether the particular person here on Earth is that entity--whether the sequence of experiences that is going on here on Earth is the one that is going to include that future experience at some point. The fact that some such sequence exists somewhere in the infinite multiverse does not prove that the particular sequence here on Earth is that sequence.

 

[PeterDonis]

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

Which are mathematical things, not physical things. We are not talking about abstract mathematics in this thread. We are talking about our actual universe and what is possible within it. So it's not enough to wave your hands and say "mathematically we know there are infinite sets with different cardinalities". Yes, we know that. But that says nothing about the cardinalities of the actual infinite sets (if there are any) that appear in our physical models, which is what we are talking about in this thread.

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.

Um, this isn't a "hand-waving statement", it's a tautology: obviously the set of possible universes does not include impossible universes.

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

This is not a hand-wave either: it's another obvious statement that contributes nothing useful to the discussion in this thread.

If you don't have anything useful to contribute to the discussion in this thread, please refrain from further posting.

 

[PeterDonis]

I am having troubles with this reasoning.

Because you're not thinking through the implications of what "you" actually means. I suggest re-reading my post #58 in response to you again, particularly the last part of it. (I reiterated some of the same points in post #72.)

 

[Physicuser]

Because you're not thinking through the implications of what "you" actually means. I suggest re-reading my post #58 in response to you again, particularly the last part of it. (I reiterated some of the same points in post #72.)

It seems a good point, thanks.

 

[Jarvis323]

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.

But there would be many worlds/yous. Every world would have a you, and a different message, and all of the possible messages would be seen by some you. One of them would see Hamlet.

This is one reason why MWI is disregarded by some people, because it implies absurdly statistically unlikely outcomes in some worlds.

 

[PeterDonis]

there would be many worlds/yous

Please, please be clear about exactly what you mean by "you". I have posted repeatedly about this already.

You, here and now on Earth, represent an initial portion (from your first experience up to now) of a particular entire sequence of human experiences--a particular person. But you, here and now on Earth, do not know exactly which entire sequence of experiences you are--which entire sequence the sequence of you here on Earth up to now is an initial portion of.

If Tegmark's reasoning is correct, whichever entire sequence of experiences your experience here on Earth up to now is an initial portion of, there are many other entire sequences of experiences elsewhere in the infinite multiverse that are identical. But that statement tells you nothing about which entire sequence of experiences your experience here on Earth up to now is an intial portion of. So it tells you nothing about what future experiences you, here and now on Earth, you should expect. Whichever future experiences you end up having, yes, there will be many other sequences of experiences, realized elsewhere in the infinite multiverse, that are the same; but that tells you nothing about which future experiences those will be.

In other words, there are many different possible entire sequences of experiences, all of which start with the same initial portion as your experience here on Earth up to now. Only one of those sequences is the one being instantiated here on Earth. So the term "you" is ambiguous: it can refer to just the particular entire sequence of experiences being instantiated here on Earth, or it can refer to the set of all possible entire sequences of experiences that have the same initial portion as the one being instantiated here on Earth--your experience here on Earth up to now. You seem to be using it with the latter meaning, but the latter meaning doesn't say anything about what the you here on Earth will experience. It is perfectly possible to formulate a notion of "probability" in which it is meaningful to say that the probability is absurdly tiny that you, here on Earth, will see Hamlet emerge from a series of random quantum fluctuations. Which is all we can actually establish from experiment.

 

[Jarvis323]

Please, please be clear about exactly what you mean by "you". I have posted repeatedly about this already.

You, here and now on Earth, represent an initial portion (from your first experience up to now) of a particular entire sequence of human experiences--a particular person. But you, here and now on Earth, do not know exactly which entire sequence of experiences you are--which entire sequence the sequence of you here on Earth up to now is an initial portion of.

If Tegmark's reasoning is correct, whichever entire sequence of experiences your experience here on Earth up to now is an initial portion of, there are many other entire sequences of experiences elsewhere in the infinite multiverse that are identical. But that statement tells you nothing about which entire sequence of experiences your experience here on Earth up to now is an intial portion of. So it tells you nothing about what future experiences you, here and now on Earth, you should expect. Whichever future experiences you end up having, yes, there will be many other sequences of experiences, realized elsewhere in the infinite multiverse, that are the same; but that tells you nothing about which future experiences those will be.

In other words, there are many different possible entire sequences of experiences, all of which start with the same initial portion as your experience here on Earth up to now. Only one of those sequences is the one being instantiated here on Earth. So the term "you" is ambiguous: it can refer to just the particular entire sequence of experiences being instantiated here on Earth, or it can refer to the set of all possible entire sequences of experiences that have the same initial portion as the one being instantiated here on Earth--your experience here on Earth up to now. You seem to be using it with the latter meaning, but the latter meaning doesn't say anything about what the you here on Earth will experience. It is perfectly possible to formulate a notion of "probability" in which it is meaningful to say that the probability is absurdly tiny that you, here on Earth, will see Hamlet emerge from a series of random quantum fluctuations. Which is all we can actually establish from experiment.

This is all true. But one being that shares your prefix up to this point, will experience a chain of experiences that includes setting up a device and seeing Hamlet printed. In fact one will experience being in a reality where experimentally, all quantum random number generators always print Hamlet and nothing else. Being one who experiences that will be absurdly unlikely. But it will happen according to MWI. For them, experimentally, they would appear to live in a quantum Hamlet universe.

 

[PeterDonis]

one being that shares your prefix up to this point, will experience a chain of experiences that includes setting up a device and seeing Hamlet printed

Yes. But among the set of all beings that share the same prefix (good shorthand term, btw!), only a very tiny fraction will have that experience.

one will experience being in a reality where experimentally, all quantum random number generators always print Hamlet and nothing else

Yes, but this will be a much, much tinier fraction than the subset above.

it will happen according to MWI. For them, experimentally, they would appear to live in a quantum Hamlet universe

Yes, this is one argument for being skeptical that the MWI is true. It probably needs to be discussed in a separate thread if you want to go into it in more detail, since this thread is supposed to be about QI without the MWI.

 

[votingmachine]

Which are mathematical things, not physical things. We are not talking about abstract mathematics in this thread. We are talking about our actual universe and what is possible within it. So it's not enough to wave your hands and say "mathematically we know there are infinite sets with different cardinalities". Yes, we know that. But that says nothing about the cardinalities of the actual infinite sets (if there are any) that appear in our physical models, which is what we are talking about in this thread.

I thought the original question was precisely about whether everything imaginable happens in a MWI. Maybe I focused on the wrong part:

... a person like you in another galaxy or a brain that popped out in the middle of space, so even if there is no causal connection between them, there is a subjective sensation of continuity...

I'm not sure of the cardinality of the set of MW, but it seems smaller than the set of MW we can imagine. And that might be impossible. I'm not sure why a brain is popping up in the middle of space, with the exact conscious history of another brain, on earth. I did mention impossible things because that seemed impossible.

 

[PeterDonis]

I thought the original question was precisely about whether everything imaginable happens in a MWI.

Please read the thread title. The OP does mention the MWI, but only to describe where the "quantum immortality" idea originally came from. The thread is specifically about whether something similar is possible if the MWI is not true.

Maybe I focused on the wrong part:

What the OP described there does not require the MWI. In fact, one of the rather counterintuitive points made in the Tegmark paper referenced earlier is that, in a spatially infinite universe with inflation at the start, anything that would happen in some branch under the MWI will also happen in some Hubble volume of the spatially infinite universe on a single-world interpretation of QM. The latter kind of scenario is what we are discussing in this thread.

 

[PeterDonis]

I'm not sure of the cardinality of the set of MW, but it seems smaller than the set of MW we can imagine.

This is off topic. Please start a separate thread if you want to discuss this.

 

[votingmachine]

What the OP described there does not require the MWI. In fact, one of the rather counterintuitive points made in the Tegmark paper referenced earlier is that, in a spatially infinite universe with inflation at the start, anything that would happen in some branch under the MWI will also happen in some Hubble volume of the spatially infinite universe on a single-world interpretation of QM. The latter kind of scenario is what we are discussing in this thread.

I see the link and paper now. But doesn't it also make the same point that I am after in discussing the cardinality? The Level-1 multiverse is a subset of the Level-4 multiverse. The cardinality of the two is different.

I see that an infinite spatial universe is likely to have infinitely many variations of 14 billion light-year spheres. But I think that infinite set of 14 billion light year spheres is incomplete. The cardinality is lower. There should be an infinite number of those 14 billion light year spheres with 1 hydrogen atom in them (placed at an infinite number of positions), Each with the atom somewhere slightly different. And another infinite set with 2 helium atoms.

If the cardinalities are different then we can say some things are not in there. Level-3 variations are not found in the Level-1 set.

"Level I: A generic prediction of cosmological inflation is an infinite “ergodic” space, which contains Hubble volumes realizing all initial conditions."

There needs to be proof that the infinite set of initial conditions can be mapped one-to-one to infinite space. Perhaps that proof is in one of the references, but none is presented in that paper.

 

[PeterDonis]

The Level-1 multiverse is a subset of the Level-4 multiverse.

Yes, but this does not prove that the cardinality of the latter is greater than the cardinality of the former. Remember that we are dealing with infinite sets: an infinite set can have a proper subset that has the same cardinality. (In fact that's the definition of an infinite set.)

 

[votingmachine]

Yes, but this does not prove that the cardinality of the latter is greater than the cardinality of the former. Remember that we are dealing with infinite sets: an infinite set can have a proper subset that has the same cardinality. (In fact that's the definition of an infinite set.)

True.

But I also find it difficult to swallow that a universe is determined by the initial conditions ... that seems to contradict the results we see in this section of the Multiverse. But I see the parallel between the "unitary" part of MWI and that of determinism set by initial conditions. And thus why it is possible to consider the two functionally equivalent.

It does seem like that requires hidden deterministic variables ... and I cannot resolve that with the contradiction of that assumption seen in Bell's Theorem experiments. But I suppose we could anthropically live in a subsector where the results of Bell experiments are confusing. Although I would argue that to be an identical me, there has to be that set of experimental data.

 

[PeterDonis]

I also find it difficult to swallow that a universe is determined by the initial conditions ... that seems to contradict the results we see in this section of the Multiverse.

How so?

 

[votingmachine]

How so?

If there is an identical me in an identical multiverse measuring the identical electron present, and I measure the spin in one and the position in the other then the spin and position are both knowable with infinite precision. I don't have to presuppose entanglement, I merely have to suppose multiverse identity to that moment.

Every experiment with entangled things says that the two conjugate variables CAN NEVER be known with infinite precision. The identical multiverses are Einstein's Princes.

You either have to hold that conjugate variables are knowable, or unknowable. The experimental results in this multiverse are only consistent with them being unknowable.

Put another way, the two variables can be shown to not coexist at a level beyond the uncertainty principle. But the existence of Multiverses creates a situation where even though a singular I does not know the two, the two measurements exist, on what is the same particle.

Or if there is FTL hidden variable communication, I would notice that the particle was measured for spin, and therefore, my measurement was impossible. Maybe FTL hidden variable swapping works ... it eludes me how though. The two particles are merely identical, not entangled.

 

[PeterDonis]

If there is an identical me in an identical multiverse measuring the identical electron present, and I measure the spin in one and the position in the other

Inconsistent. If the two "mes" make different measurements on the electron, they're not identical.

The rest of your post just builds on this initial error.

 

[votingmachine]

Inconsistent. If the two "mes" make different measurements on the electron, they're not identical.

The rest of your post just builds on this initial error.

Hmm. I'm stuck in a loop on that response. Of course they are not identical once they are measured, but they were before the measurement. And that seems to be the EPR objection to QM completeness.

But I'll have to think on it. It seems a circular argument.

Let me try the same thing stated another way:

6 identical Multiverses where I have entangled pairs of photons headed for the usual ABC detectors. Now the multiverses diverge and I put all 6 possible pairs of settings (AA, AB, AC, BB, BC, CC). The results of those measurements of the same pair create a requirement for a complete instruction set. And a complete hidden instruction set is incompatible with the experimental results.

That may be the same issue ... once the pairs are measured, they are non-identical. Now I can't KNOW that there was a complete instruction set, unless another multiverse has me reincarnated with the previous 6 bits of knowledge.

I could be being anthropic though ... Tegmark does warn against that trap.

 

[PeterDonis]

Of course they are not identical once they are measured, but they were before the measurement.

So what?

that seems to be the EPR objection to QM completeness

No, it isn't. The EPR objection has nothing to do with what you are saying.

The results of those measurements of the same pair create a requirement for a complete instruction set.

No, they don't. The fact that results occur for all 6 pairs of settings does not mean all of those results were predetermined.

a complete hidden instruction set is incompatible with the experimental results.

Only if it obeys Bell's locality condition.