Why do some people take “quantum immortality” so seriously?

Miscellaneous and Personal Stuff I Must Share
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Quantum immortality is basically an assertion that “If I haven’t died yet, then nothing’s killed me.” At any given time there is a theoretical alternate version of you that happened to get itself killed off, possibly by random wombat attack or spontaneous human combustion. That’s a version of you that didn’t happen to you, because you lasted long enough to read this sentence.

The argument that if you somehow kept dodging death you could be literally immortal, living trillions of years, obviously ignores the fact that sometimes there’s no possible world where you survive - and no possible alternate sequence of prior events that led to you lasting this long either. Eventually the final branch will be pruned.

Of course, the thing that differentiates quantum immunity from literal immunity (aside from that final-branch-pruning issue) is that the premise is not that you live longer, but that some other person you once had something in common with lives longer. The fact that the ‘you’ that adopted a policy of murder and human sacrifice managed to gain regeneration powers in the post-nuclear hellscape that President Nader caused isn’t going to help you out any when that piano falls out the window tomorrow. There’s literally nothing about this model that helps you out at all - in fact it’s all downsides. If you’re currently alive it means that millions of other versions of you managed to get themselves slaughtered by stupidity and misfortune and ill-timed turtle shells, and if you’re currently looking up and seeing that Steinway plummetting towards you, your only consolation is that if you weren’t such a loser you’d still be alive.

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Band name!

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You are going to need to provide a citation if you are going to call that a fact.

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We’re in Great Debates now?

It’s trivially obvious that “anything’s possible” is a false statement. The observed universe respects causality and object permanence and such, and thus it is not the case that anything imaginable is possible. This means that some things are impossible.

For example, I’m willing to hazard that no human being can be considered “alive” while frozen solid. Thus, the heat death of the universe represents the guaranteed death of all humans.

Once we’ve accepted that physical phenomena can guarantee your death in all possible worlds, it becomes clear that in an infinite universe, given infinite time, every possible timeline-verison of you will encounter a scenario where no outcome leads to survival. Such scenarios occur, and you can’t dodge them forever - any of you.

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Some speculations hold that the most fundamental laws of physics are not necessarily the same in all universes. Thus, could there be a branch of existence where, for example, entropy doesn’t happen like it does here, and the ultimate heat death of the universe is not guaranteed?

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It’s well known that if you invoke the word “quantum”, it automatically confers respectability on whatever woo you’re trying to sell. Take for instance homeopathy:

“(Weak quantum theory) predicts entanglement, which in (Quantum Mechanics) is known as Einstein-Podolsky-Rosen (EPR) correlatedness within quantum systems. According to WQT, this entanglement is not only tied to quantum systems, but is to be expected whenever a global and a local variable describing a system are complementary. This idea is used here to reconstruct homeopathy as an exemplification of generalized entanglement as predicted by WQT. It transpires that homeopathy uses two instances of generalized entanglement: one between the remedy and the original substance (potentiation principle) and one between the individual symptoms of a patient and the general symptoms of a remedy picture (similarity principle). By bringing these two elements together, double entanglement ensues, which is reminiscent of cryptographic and teleportation applications of entanglement in QM proper. Homeopathy could be a macroscopic analogue to quantum teleportation.”

http://karger.com/Article/PDF/73475

If you have no idea what the hell this person is talking about, well then you are hopelessly tangled in rational thought and have no right to dismiss homeopathy as (quantum) bullshit.

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I submit that since homeopaths are prohibited from practicing medicine due to their quackery on the subject, that new age lunatics should also be prohibited from using quantum physics terms due to their quackery on the subject.

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I think my brain just turned to mush reading that thing you posted.

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Brought to you by the great minds of: Institut für Umweltmedizin und Krankenhaushygiene

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The cure for homeopathy is less of it.

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Or none of it.

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That’s enough to kill a horse.

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Yikes

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If you liked that, I’ve got a “robust scientific hypothesis” that’ll really create perturbations in your geodynamo.

Read the paper before you scoff. It’s got it all.*

*Funded by NIH grants, so it’s gotta be science.

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^^Thanks. Good reading!

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How is it that you, uniquely, know the ultimate reality of things?

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Quantum immortality, while obviously speculative, is a legitimate scientific notion, at least to the degree that all questions about the interpretation of quantum mechanics are. It’s definitely not some sort of Deepak Chopra-woo. Serious scientists have seriously debated this issue—one of the more famous ones being Max Tegmark. Indeed, he’s proposed it as a way to test the many worlds interpretation, since it’s the only issue on which it gives different predictions from other mainstream interpretations.

This wouldn’t help: there’s a nonzero chance that somewhere in the universe, at some point, some particles spontaneously assemble into a copy of yourself. Now, it depends somewhat on your philosophical predilections of whether you consider a perfect copy of yourself with contiguous experience to yours ‘you’, but that’s nothing but the old Star Trek teleporter argument—if you’re happy being teleported, you should be happy being ‘resurrected’.

Likewise, the heat death won’t stop you: there’s always a nonzero chance that a local fluctuation in entropy provides enough usable energy to carry on for just an instant longer. As long as that’s true, there’ll always be a branch in the wave function where you continue to exist.

But the conclusion of the quantum immortality argument still can’t be correct. For one, there’s a simple way to kill any given observer: say |Ψ0> is the state of the universe before they were born, and |Ψ1> is the state of the universe today. Then, both are related by a unitary transformation: |Ψ1> = U|Ψ0>. But then, since unitary evolution is deterministic, there exists a unitary transformation U-1 such that U-1U = UU-1 = Id (the identity transformation), and hence, we only need to apply U-1 to the entire universe at the current moment, and get U-1|Ψ1> = |Ψ0>; in other words, a future state of the universe where the observer is absent. Hence, the logic of the quantum immortality idea can’t be correct: there are ways to remove a conscious observer from the universe. That much must be clear, simply because there are ways to create conscious observers (some of them quite fun), and physics, at least if the MWI is correct, is overall time-reversal invariant—whatever you can do, you can also undo.

Now, it’s quite hard to undo these things, to the great chagrin of many who thought that forgetting a condom just this once won’t be such a big deal. The above example involves recoherence: the rejoining of branches that previously split apart. This is a fantastically unlikely process—but it does have a non-zero likelihood of occurring. And the quantum immortality idea depends on the notion that the probability of surviving can be arbitrary small; but any non-zero likelihood of death dooms the quantum immortality argument: it’s not the case that there will always be a surviving copy of the observer.

However, this still means that you might expect a quite long life, narrowly escaping death again and again. But there’s no reason to believe that the ‘re-setting’ of the universe is the only way to snuff out somebody for good. If consciousness can ‘fade in’, with a new child being born, there must exist some mechanism for it to ‘fade out’—in the extreme, just taking that particular individual brain through whatever steps it took to become conscious in the reverse. Consciousness isn’t on-off, isn’t a binary thing; we can be less conscious now than we were just the moment before (if you doubt that, various substances are available for experimentation; I recommend a good scotch).

It’s a sort of sorites paradox: when does a conscious being cease to be conscious? And I don’t think there’s any hard-and-fast line. And that means, there’s also no hard-and-fast point at which consciousness must travel down another branch, so to speak. But there will, eventually, be a point where there’s no conscious experience to speak off anymore. So there will, eventually, be a point where any branching off is too late. Hence, while there’s no cul-de-sac, no circumstances such that death is guaranteed by some contrivance, there are roads to nowhere—continuous descents into states of ever-diminishing consciousness, where at some, unsharply defined point, there just isn’t any you within you anymore.

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Which fallacy is this?

No, spontaneous copies of me appearing everywhere aren’t me. If a copy of you appeared in front of you right now, you wouldn’t really think that they’re the same entity as you, no matter how good the copy is. -Unless they claimed to be a time traveler or something, anyway. Because while all it takes for an individual to think they’re the same entity is contiguous experience. for anybody else to agree with them that requires continuous existence.

…or a sort of societal acceptance/ignorance. The continuity of existence across transporters is only uncontested until something goes wrong and two of you pop out - at that point it becomes a philosophical debate.

Also, speaking of philosophical debates, this is the Theseus’s ship paradox. And since I lean to the side of “Oh, we call it the same ship, but it really isn’t. Also I’m really not the same person I was when I was in college”, I’m not really a good recipient of the sorts of arguments you’re making anyway.

Given that being conscious consumes energy, doesn’t this break the laws of thermodynamics?

Hold on a tick - nobody’s proposing that there’s no way for a person to die. They’re proposing that even though there are mechanisms to off people, the point of quantum immortality is that there’s some alternate universe where they never quite get around to happening.

Well, some people are saying this. I’m saying that for quite a lot of people there are some busses that you can’t dodge. Though I should probably note that I’m not saying that everyone will be hit by a bus. Some people could theoretically be quantumly immortal. But I don’t think that we can be confident everyone is. Quantum immortality is not just positing that you might have a version of yourself that ends up in a random bubble of warmth that breaks the laws of physics (and provides burritos and sprite) forever; it’s saying that it’s guaranteed that there’s some not-impossible causality path that leads to this for everyone.

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Sure, but that’s not the situation. Rather, it’s that an identical copy of you at the point where you were snuffed out spontaneously arises somewhere else—i. e. like a Star Trek teleporter. Failing that, you may always appeal to quantum tunneling—just in the instant you were about to be killed by whatever method you devised, you spontaneously tunneled out of harm’s way. (Of course, quantum mechanically speaking, there’s no difference between the two scenarios.)

There will always be a state where such a thing happens with a non-vanishing amplitude; hence, there’s no guaranteed killing scenario.

No. The second law is statistical; entropy increases on average. Spontaneous fluctuations to lower entropy are possible, just vanishingly unlikely—and that’s all that’s needed.

No, but the proposal is that there’s nothing that kills you with 100% certainty. Every death scenario has some ludicrously unlikely possibility of survival. Strapped to a nuke? Well, you tunnel to a habitable world 50 light years away at the moment of explosion. Or, for people who believe consciousness can be simulated, in the far future, somebody sets up a simulation of you at exact the point of death. If you want to claim that’s not you, well, then you’ll have trouble explaining how whatever wakes up tomorrow after you go to sleep today is you, as well.

Point is: you can always come up with some story, the proponents of quantum immortality allege, where consciousness continues. It might be a ludicrously unlikely story, but that’s fine—it merely need not be impossible.

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Quantum mechanically speaking there’s no difference between a copy of you appearing in front of you right now, and that copy appearing elsewhere after you’ve been hit by a bus. And since the copy randomly appearing in front of you now isn’t the same person as you are, then neither is the person who randomly appears elsewhere. (And nether is the person who quantum tunnels, according to you.)

Nobody’s contesting that copies of a person can’t be created - that’s just a matter of getting the right matter together and arranging it into an exact copy of the original person. That’s a strictly mechanical process and happens all the time. But the issue here is whether the copy and you are the same single entity. And there are two ways of looking at this question:

  1. “Of course not - the words ‘the same entity’ have a meaning, and while it’s difficult to describe that meaning in a sound byte, we all pretty much know what it means, and carbon copies aren’t it.”

  2. “Eh, who cares if original Fred is dead - copy Fred is just as fun at parties! Transporters rock! Woot!”