I Quantum Immortality without MWI?

[PeroK]

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.

Without MWI, that's true of our universe: that a random character generator could produce Hamlet, but it is absurdly unlikely. And we can run an experiment to confirm/justify that claim.

You claim that if MWI is true then there must be a random character generator somewhere that generates Hamlet (and nothing but Hamlet).

What I ask is at least a description of an experiment that would test that claim. If you cannot provide at least an outline of how you would test that (to see whether it's true of not), then I claim that statement is physically meaningless and metaphysics, rather than physics.

We can all wave our hands and say there must be this and there must be that, but unless you can propose an experiment to confirm what you're saying, then it's not physics.

Believing MWI doesn't give anyone the right to abandon the principles of confirming claims by experimental evidence. This is my challenge to all your claims: that you are using a blind belief in MWI to avoid actually thinking about the universe from an experimental point of view and claiming things to be true that cannot be confirmed experimentally.

Further, I suggest that if MWI is true and even if you could somehow investigate more than one branch of the wavefunction, then (in any experiment constrained by the speed of light, and the lifetime of the universe) the chance of finding such a machine is still absurdly unlikely. So, from a physics standpoint it is still absurdly unlikely that you can show such a thing to exist.

 

[PeterDonis]

You claim that if MWI is true then there must be a random character generator somewhere that generates Hamlet (and nothing but Hamlet).

What I ask is at least a description of an experiment that would test that claim.

If you agree that without the MWI, a random character generator would have an extremely tiny, but not zero, probability of producing Hamlet and nothing but Hamlet, then it must be the case, because all QM interpretations use the same underlying math, that in the MWI, there would be a branch in which a random character generator produced Hamlet and nothing but Hamlet. You don't need an experiment to test that.

Bear in mind that the MWI is an interpretation of QM. That means it makes all of the same experimental predictions as any other interpretation of QM, including whichever one you are using to make the claim that without the MWI, there would be an extremely tiny, but not zero, probability of a random character generator producing Hamlet and nothing but Hamlet. So you can't distinguish between those two interpretations by any experimental test. All you can do is observe that they both use the same underlying math; the only difference between "there is an extremely tiny but nonzero probability of X occurring" and "there will be a branch in which X occurs" is which QM interpretation you choose.

 

[PeroK]

If you agree that without the MWI, a random character generator would have an extremely tiny, but not zero, probability of producing Hamlet and nothing but Hamlet, then it must be the case, because all QM interpretations use the same underlying math, that in the MWI, there would be a branch in which a random character generator produced Hamlet and nothing but Hamlet. You don't need an experiment to test that.

The adoption of the idea where we do not need experimental evidence for these claims, I suggest, is allowing metaphysical wool to be pulled over our eyes.

I'm drawing a distinction between the mathematics and the physics. Mathematically, you have an infinite sequence of worlds. But, once you introduce the need for experimental confirmation of these claims, you can't process an infinite sequence. I would like to insist that:

Everything that is claimed to exist has at least a theoretically plausible experiment that could find it.

This would ultimately allow us to assign some sort of probabilities to events in MWI according to the maximum practical probability of finding it - given certain fundamental constraints, such as the speed of light, the amount of available energy in the observable universe and the lifetime of the universe.

In other words: if we hypothetically dedicated all the available resources in the observable universe for the lifetime of the universe to finding out Hamlet machine, then the probability of finding it is still absurdly small. And that would allow us to say - with some well-defined physical meaning - that's it's absurdly unlikley that there is one. And to claim the definite existence of something we will (almost certainly) never find is metaphysics.

In a nutshell, my argument against blindly accepting the existence of everything that MWI may produce is to impose at least some measure of experimental verifiability. You could argue with my methodology, but I suggest some experimental methodology (that goes beyond hand waving) is necessary for us to be discussing physics at all.

 

[Jarvis323]

What I ask is at least a description of an experiment that would test that claim. If you cannot provide at least an outline of how you would test that (to see whether it's true of not), then I claim that statement is physically meaningless and metaphysics, rather than physics.

We can all wave our hands and say there must be this and there must be that, but unless you can propose an experiment to confirm what you're saying, then it's not physics.

If this is true, then quantum interpretations are not in the realm of physics.

Believing MWI doesn't give anyone the right to abandon the principles of confirming claims by experimental evidence. This is my challenge to all your claims: that you are using a blind belief in MWI to avoid actually thinking about the universe from an experimental point of view and claiming things to be true that cannot be confirmed experimentally.

Who has said they believe in MWI? Personally, I don't.

Further, I suggest that if MWI is true and even if you could somehow investigate more than one branch of the wavefunction, then (in any experiment constrained by the speed of light, and the lifetime of the universe) the chance of finding such a machine is still absurdly unlikely. So, from a physics standpoint it is still absurdly unlikely that you can show such a thing to exist.

If MWI is true, then the mathematics implies Hamlet machines. If what it implies is false, then MWI would have been false in the first place. We've assumed it was true as a thought experiment already.

 

[Jarvis323]

In other words: if we hypothetically dedicated all the available resources in the observable universe for the lifetime of the universe to finding out Hamlet machine, then the probability of finding it is still absurdly small. And that would allow us to say - with some well-defined physical meaning - that's it's absurdly unlikley that there is one.

You can argue that it's not worth discussing since it's just mathematics we're discussing. But the argument you've given is self contradictory. If we discuss mathematics, then we should be consistent.

If experimentally you find it extremely unlikely for a Hamlet machine to exist, that is fine.

But if you claim that a world where all quantum random number generators are Hamelet machines doesn't exist, and you've assumed many worlds interpretation is true, then all you've done is contradict your assumption.

In other words, even if we do some hand waiving and assume you could disprove a Hamlet machine exists, then all you could hope to do is disprove the assumption (MWI).

Physics is based on math. If we can't discuss the math itself (because in your opinion mathematics is just hand waiving), then we can't do any kind of physics in the first place. In other words, you're claiming physics isn't physics.

 

[akvadrako]

In a nutshell, my argument against blindly accepting the existence of everything that MWI may produce is to impose at least some measure of experimental verifiability. You could argue with my methodology, but I suggest some experimental methodology (that goes beyond hand waving) is necessary for us to be discussing physics at all.

Testing MWI might be possible if it implies QI and the other interpretations don't. QI can be tested because it assigns different probabilities to "living to 200" and "living to 1M" than there not being QI. So each time you find yourself living longer than you expected, seemingly by being lucky to be in the right world, it should increase your credence of QI and hence of MWI.

 

[PeroK]

If this is true, then quantum interpretations are not in the realm of physics.

I think it's generally accepted that taking an interpretation literally is metaphysical. But, an interpretation is a practical way of making sense of the theory.

In the case of MWI, there is a possibility that it might in future be experimentally verifiable.

Who has said they believe in MWI? Personally, I don't.

Okay, fair enough.

If MWI is true, then the mathematics implies it. If what it implies is false, then MWI would have been false in the first place. We've assumed it was true as a thought experiment already.

I'm saying you still need to make physical sense of the mathematics. In a way, I'm defending MWI by saying you can have it as a mathematical framework and then impose an experimental methodology which means you can (in a physically meaningful way) assign probabilities to things - in terms of some sort of maximum probability of such a things ever being "found" - assuming you can simulate looking through as many worlds as possible, for example.

Alternatively, you could take MWI with a finite branching - that's perhaps a simpler way to achieve the same thing.

 

[PeroK]

(because in your opinion mathematics is just hand waiving), then we can't do any kind of physics in the first place. In other words, you're claiming physics isn't physics.

There's no way to argue with such a nonsensical misrepresentation of what I've said.

 

[Jarvis323]

There's no way to argue with such a nonsensical misrepresentation of what I've said.

I apologize. I am coming around to understanding your point better I think. If I'm not mistaken, you're disagreement seems to be in making the assumption.

 

[mattt]

As others pointed out earlier, the existence of a Hamlet machine does not depend on the many-worlds interpretation of QM.

In the many-worlds interpretation of quantum mechanics, it exists as a branch of the wave function of the universe, whereas in type 1 scenario of Tegmark, it exists in some bubble.

In both cases, the probability of finding it experimentally, it's almost zero.

On the other hand, I see no problem in discussing about what the mathematics of quantum mechanics imply.

 

[votingmachine]

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

OK. I was seeing Tegmark's argument as requiring predetermined conditions and a deterministic path ... I see the difference now. It's an infinite number of multiverse's with every path taken for everything from each and every initial starting condition. I thought that each multiverse was being called determinist. All 6 of my parallel multiverses had indeteminate potential.

So there is no contradiction.

 

[PeterDonis]

The adoption of the idea where we do not need experimental evidence for these claims, I suggest, is allowing metaphysical wool to be pulled over our eyes.

As @Jarvis323 points out, this argument would apply to any interpretation of QM, not just the MWI. None of them are experimentally testable as compared with other interpretations, because they all make the same predictions for all experimental results (since they all use the same underlying mathematical machinery to make those predictions).

One of the reasons we spun off this subforum is to allow discussion of QM interpretations in spite of the above fact. We can't stop people from wanting to discuss the topic, but we also can't resolve discussions of it the way we can resolve discussions of things that are experimentally testable--i.e., the way we resolve disagreements in other forums here at PF.

So while your statement is true, it is (rather ironically) off topic in this particular subforum, because it's already understood that no claims that anyone makes about QM interpretations are experimentally testable.

Further, as I've already pointed out in this thread, discussion of the MWI is off topic because the thread is specifically supposed to be about what the possibilities are for quantum immortality without the MWI.

 

[onqm]

Yes, I know the concept. Boltzmann Brains are usually dismissed saying that if you were one, it would be more probable to don't observe a coherent world. Mallah makes a similar objection to QI: if it was true and you could be live indefinitely, since there are more "survival" observer moments, it would be more probable to you being experiencing one of these than one of the few "normal".

A doubt I have is if the important thing here is the number of observers or observer-moments, I mean, if there are 100 versions of you, 99 drinking water and 1 drinking coke, since the 99 observer are same observer-moment, what are the chances? 99-1 or 1-1?

Hello. I'm Jacques Mallah, and was invited to join this conversation. (I'm not sure which member here emailed me.)

The 'doubt' raised in the above quote is important to the topic. If the effective odds of drinking the water were 1-1 instead of 99-1, then all types of conscious observations (among those that do actually exist somewhere in the wavefunction) would have equal effective probability. Our observations would then be very atypical, for reasons that should be obvious (such as seeing a lot of regularities around us). So we can dismiss that and conclude that the observers that are more physically numerous (or in the MWI, have more amplitude) are in fact more "probable" and not equally "probable".

So by the same reasoning, observations within a lifespan than does not require rare events to continue would be more "probable" than those outside of that. Thus, FAPP, no immortality or unusual longevity.

 

[Physicuser]

Hello. I'm Jacques Mallah, and was invited to join this conversation. (I'm not sure which member here emailed me.)

The 'doubt' raised in the above quote is important to the topic. If the effective odds of drinking the water were 1-1 instead of 99-1, then all types of conscious observations (among those that do actually exist somewhere in the wavefunction) would have equal effective probability. Our observations would then be very atypical, for reasons that should be obvious (such as seeing a lot of regularities around us). So we can dismiss that and conclude that the observers that are more physically numerous (or in the MWI, have more amplitude) are in fact more "probable" and not equally "probable".

So by the same reasoning, observations within a lifespan than does not require rare events to continue would be more "probable" than those outside of that. Thus, FAPP, no immortality or unusual longevity.

Hello.
I misunderstood your paper, then, I thought you were arguing the opposite.

 

[onqm]

Physicsuser,

I would like my writings to be clear, so would appreciate it if you could explain what was not clear in there.

In the post I quoted, you correctly noted that I was making an objection to "QI", and that I was saying that if it were true than our actual observations would be of low "probability" as one argument against it. So I actually thought that you had understood what I was saying.

To be clear, in the language used in this thread, I argue that "identity of indiscernibles" (plus MWI or sufficiently many similar planets of the appropriate sort in a large universe) would have commonly observable consequences that already show it to be false with high Bayesian probability. The paper also includes other arguments against "QI".

 

[Anixx]

However, could this work even if MWI is not true?

I had a e-mail conversation with Max Tegmark on this issue. He agreed that not only MWI, but other interpretations also imply quantum immortality.

 

[Anixx]

all of those branches will have the same classical dynamics

Wrong. There are branches which are highly improbable.

 

[PeroK]

I had a e-mail conversation with Max Tegmark on this issue. He agreed that not only MWI, but other interpretations also imply quantum immortality.

I guess that's the case closed then.

 

[PeterDonis]

There are branches which are highly improbable.

Highly improbable in the sense of very finely tuned initial conditions, yes. But the dynamics from the initial conditions, whatever they are, is the same in every branch.

 

[PeterDonis]

I guess that's case closed then.

No, the fact that Tegmark makes the claim doesn't necessarily mean it's correct. I would like to see an actual paper laying out the argument.

 

[PeroK]

No, the fact that Tegmark makes the claim doesn't necessarily mean it's correct. I would like to see an actual paper laying out the argument.

If the man says he has an email, how can you argue with that?

 

[PeterDonis]

If the man says he has an email, how can you argue with that?

An email isn't a textbook or peer-reviewed paper.

 

[Anixx]

Highly improbable in the sense of very finely tuned initial conditions, yes. But the dynamics from the initial conditions, whatever they are, is the same in every branch.

No. There are branches with improbable dynamics as well. There are branches with all possible dynamics.

 

[Anixx]

If the man says he has an email, how can you argue with that?

Of course, he just expressed his opinion.

 

[PeterDonis]

There are branches with improbable dynamics as well.

Why? The laws of physics are the same in all the branches.

 

[Anixx]

Why? The laws of physics are the same in all the branches.

Not probabilistic laws though. A "weight" of a branch is proportional to its probability, but even for the least-probable outcomes there are branches.

 

[PeterDonis]

Not probabilistic laws though.

Please read the thread. These issues have already been discussed.

 

[akvadrako]

I had a e-mail conversation with Max Tegmark on this issue. He agreed that not only MWI, but other interpretations also imply quantum immortality.

This is not what he has said publically and without seeing his exact words it's hard to reconcile with his quotes on the wikipedia page, where he says QI is not real even given MWI.

But it doesn't matter much since neither is a rigorous argument but more of a casual opinion.