I see lots of examples of what happens when laws of physics are over-interpreted, over-extrapolated, or basically just taken too seriously. It seems to me the net result is always some form of "magical thinking", of exactly the same type that scientists are normally skeptical. I find this such a curious phenomenon that I thought it might be interesting to explore a thread on it. Examples of magical thinking I have in mind include time travel and Shrodinger's cat, but it might be best to start with the most crystal clear example I can find: "quantum immortality". Consider this link on the related topic of "quantum suicide": http://science.howstuffworks.com/quantum-suicide.htm.

The idea is that in the many-worlds interpretation of quantum mechanics, there will always be one world where the gun doesn't fire even after any number of trials, and since consciousness (for some reason, don't ask me why) cannot end if there is some world where it doesn't end, the consciousness can never perceive the gun as firing so the gun never will-- and the person will perceive a miraculous number of failures of the gun to fire. (This is more generally called "quantum immortality"). I'd say this is a pretty obvious example of magical thinking on the part of mainstream physicists (it was developed by the brilliant Max Tegmark, but I don't know how seriously he takes it). To put this into better perspective, the link at one point expounds:

There you have it, it is apparently possible to exit the scientific method, yet still somehow be "rooted" in it. So, is this really an exploration of the ramifications of physical theory, or is it just a make believe fantasy inspired by physics? If the latter, from whence comes this penchant for replacing normal skepticism with magical thinking when the language, if not the substance, of physics can be applied? Or does anyone take this seriously enough to think it is either true, or false in such as way as to be evidence against the many-worlds interpretation?

Well, in other fields they use a reducto ad absurdum to find out when they've made a mistake.

To me, the value of a thought experiment lies in helping me to understand observations and to predict events. If it fails to do either it's not much use to me. I once had a chap tell me than when he looked at a wall he saw a wall, but when he looked away there was only a swirling malestrom of plasma. I didn't have the heart to tell him I could see that the wall was still a wall even when he wasn't looking at it.

this reminds me of the joke about the woman who, ever where she touched on her body, it hurt, so she thought that she must be really injured-but had she taken the time to study the situation, she might have realised, that it was her finger that was damaged.

a dumb blond joke, I think.
I hate dumb blond jokes, but it shows the value of looking for other explanations for experimental data.

My favorite magical thinking example is using quantum entanglement to advocate the non-locality of the consciousness.

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Just to be clear, are you saying that the many worlds theory itself is magical thinking, or just the interpretation quoted?

Yes, that's an excellent point, I feel much the same way. Indeed the Shrodinger's cat idea was originally intended as just such a reductio ad absurdum for the Copenhagen interpretation. The problem is, sometimes it is the argument in the reductio, not what it is trying to refute, that is absurd-- as in the Shrodinger's cat paradox.

The problem with the cat paradox that so few seem to appreciate is that "pure states" (or "state vectors") in quantum mechanics represent a state that the system is prepared in by some type of measurement (in the general sense of "known preparing influences", not necessarily a conscious observer). There are no exceptions, QM never uses state vectors in any other way, so to imagine they are something more than that is pure magical thinking. The cat/geiger-counter system is not prepared in such a state (due to untraceable noise modes in macro systems that cause decoherence and can never be reigned in), so it simply does not have a state vector. To assert otherwise is to leave science and enter the realm of magical thinking. Physics was never a promise that the universe had to conform to our philosophies of physics. Why does this staggeringly simple resolution of the "paradox" seem so sacrilegious to most physicist/magical thinkers?
I'm on your page. This particular thought experiment would be very informative if you could really sit in front of a gun set up that way and use the thought experiment to explain why you can go click, click, click..... over and over. Anyone wanna try that experiment? (Please don't.) Or it might be meant as a refutation of the many-worlds interpretation, but it fails at that too, because you (the consciousness) can't survive to say you refuted it (unless you didn't refute it), and no one else around sees it as distinguishing in any way. I'd say you both have a pretty valid point there-- and your anecdote is a marvelous demonstration of the difference between reality and how we choose to conceptualize it.

Yes, I find a lot of writing on quantum entanglement to be a leading source of semi-scientific magical thinking. It ranges from just plain wrong stuff, to stuff that really isn't supportable by experiment but is rather part of an arbitrary interpretation of experiment (like the role of "influences"). There's a thin line between interpretation and what might be termed magical thinking, and crossing that line is one of the main access points between science and magic.

I think many-worlds is one way of imagining what is going on, but it is not actually part of the science. What makes it magical thinking is taking it too seriously, until it is elevated to the level of "reality" despite a complete lack of evidence it can be thusly attached.

Yes, magical thinking does indeed result from off-kilter speculation and incomplete understanding of scientific concepts. But an important point to note is that not all speculation is off-kilter. Until the experimental evidence is in, you can't rule something out if it has a basis in an existing theory, any more than you can simply assume it's true.

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Actually, it'll fire about half the time, unless there is something specific about the nature of the particle source, giving the guy worse odds than Russian roulette.

It seems to me that a whole lot of needy solipsism and BS has attached itself to a few speculative interpretations of quantum physics.

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True-- you really can't rule anything out until the experimental evidence is in, and even then the "ruling out" is provisional to that general experimental context. But the same may be said about all magical ideas. There is nothing in the OP that distinguishes it, other than that it can be expressed in the language of quantum mechanics.

The idea is, it will only fire half the time for everyone else. But the consciousness cannot perceive its own end, so it must find itself in whatever "many-world" in which the consciousness continues (along with the infinity of other new consciousnesses that are spawned in every event that splits into all those possibilities). Indeed, how can any of us refute this-- have our consciousnesses ended? The claim is that many-worlds interpretations require that all consciousnesses perceive immortality (and only come to an end in universes that contain other consciousnesses). I can't say more about it because I do not maintain that this is saying something valid, I view it as taking physics into a realm where it does not belong and has not been established as useful (indeed, in this case it would be fatal!). But it does lead to the "magical thinking" that concludes that a consciousness might be able to tap into the many-worlds so as to "choose" whichever one allows it to continue, and this is not violated by any principle of physics (for the proponents of believing in everything that is not ruled out by our knowledge).I agree. I'm just saying that if you look around, you see that phenomenon in a lot more places than you might initially expect, often in the context of consciousness, or anthropic principles, or time travel, or superluminal transit. But I picked this because I think it is one of the clearer examples of what you are talking about.

Note also that my issue is not with the "speculative" character of the intepretations; that kind of suggests that one interpretation is right and we just don't know which one. I'm saying much more: that the whole idea of thinking that an interpretation is a description of reality is just a wrong application of physics in particular and the principles of science in general. An interpretation is whatever is in your head that allows you to do the physics, but the physics is defined only by what is done. Yes one interpretation might do a better job of finding new physics, but the process that establishes the new physics will be the scientific method-- until then it's pure magic, like all the rest.

I think that the same could have been said about any of the thought experiments, especially quantum entanglement experiments, before they were attempted. Calling them magical thinking is an unfair label, particularly in hindsight.

Why a quantum input to the trigger then? Why not plain old-fashioned gunpowder, primer, hammer? If one takes the many worlds interpretation, there are still worlds where the gun doesn't fire, there are just a heck of a lot fewer (orders and orders of magnitude...) of them compared to those that do when the two interacting objects are macroscopic systems rather than microscopic particles.

If you only count the misses and not the hits, why wouldn't doing the same thing with an ordinary gun be just as valid an example? Or is there some finite probability threshhold where these guys start assuming it's the only possible outcome (even though it's still far short of any reasonable confidence?)

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Entanglement is a perfect example of magical thinking, yes, but not in the way you mean here. The thought experiment, which is easily translated into predictions of perfectly feasible real experiments (without the dire consequences of quantum suicide), is a perfectly straightforward application of wave functions, the beating heart of quantum mechanical information processing. It relies on nothing other than a multiple-particle wave function-- a concept whose value has proven reliable over and over in seemingly more mundane circumstances that involve the manipulation of nonlocal information. The sole reason that the experiments had to be done is that they were counterintuitive, and all kinds of unsubstantiated interpretations have been given to those results.

To clarify, claiming that a result is mysterious simply because it is counterintuitive based on one particular expectation mode is a form of magical thinking-- it is over-extrapolating the lessons of classical experience. Then that is further compounded by the additional magical thinking that the straightforward multiple-particle wave function prediction for the experimental result corresponds to anything beyond a simple prediction.

In other words, there is additional magical thinking in the interpretation of that result as "spooky action at a distance". It is only "spooky" insofar as everything we have ever discovered about our universe is spooky (in the irony of ironies about Einstein's remark, what could be "spookier" than relativity!), and it is only "action" insofar as we partake in unsupported magical thinking that particles encode local information, even when quantum mechanics tells us that the information is encoded in the wave function: a nonlocal entity. But this is the point-- there is no nonlocal "action" or "influence" in entanglement, the nonlocal information was already embedded into the analysis by the use of a wave function, and that information reflects the knowledge of the person applying the wave function in ways that always respect causality. So at the end of the day, entanglement is tantamount to saying "multiple-particle wave functions make correct predictions for the person who uses them to summarize his/her information about the system". That last statement is the one way to emerge from the fray without doing anything outside the scientific method, i.e., without magical thinking. The magic to avoid is imagining that "there is" a wave function for a system, in some absolute sense (back to the cat again).

In short, you are claiming that my "blowing the whistle" on magical thinking would rule out predictions based on quantum mechanics, but I am saying just the opposite: predictions based on the empirical prescriptions of quantum mechanics are proper scientific use of what quantum mechanics is for: the processing of quantum mechanical information by a practitioner making a prediction. I am instead blowing the whistle on expecting quantum mechanical predictions to not work on the grounds that they don't agree with our preconceived philosophies about what constraints must apply on processing experimental information (to wit, that it must be extracted from local storage in the particles, as holds in classical physics). You see, when overinterpreted, classical physics can lead to magical thinking about how reality "has to be" just as much as can quantum mechanics.

Excellent question. The idea behind many-worlds starts with the supposition that "there is" a wave function for a macroscropic system (like the person/gun system). If there is such a wave function, and the system is closed, then the system should evolve according to the Shrodinger equation-- a deterministic evolution equation for that wave function. When measurements occur, there are complex couplings set up within that closed system that create correlations between certain outcomes and destroy the correlations between other outcomes (that's what interference does, the fundamental agent of evolution of a wave function). So you don't get particular outcomes, you get particular correlations between outcomes (a certain spin and a gun that fires, another spin and a gun that doesn't), each with an associated probability. This is what is known as a "mixed state" in regard to the state of the gun, even as we continue to imagine that the whole system has a pure-state wave function (which is completely unspecifiable, of course, which is why it is magical thinking).

But the point is, if all you get are correlations, you don't yet have a universe-- the universe has to "pick one". The many-worlds interpretation is an effort to do something that is completely scientifically unnecessary-- get around the problem that our physics has no way to tell us which possible outcome our universe will "pick". We just say they all happen, and we end up in one branch. Note that classical physics doesn't do that-- in a classical treatment, if you roll a die, there is only one outcome, you just may or may not know what it was. But a point I've tried to make before, and what you are saying as well here, is that this is actually no different from quantum mechanics, because the creation of a quantum mechanical mixed state is exactly the same as rolling a die and not looking at it. The universe's "pick" occurs after the quantum mechanics is already over, because quantum mechanics uses specifiable wave functions, not imagined ones for the "whole system". So I agree with you-- there's nothing different in the quantum suicide scenario whether or not a quantum system is used as the trigger.
Yeah... exactly. Expecting anything to be different if you hook up the trigger to a quantum system is a classic example of magical thinking-- and it is not a prediction of quantum mechanics (it's not even obviously a prediction of the many-worlds interpretation, for that matter).

I'm unsure about the relationship of magical thinking as you define the term to untested physics, for example, what about theories that have at present no experimental validation, (I'm thinking of string theory) yet extrapolation seem to be routinely carried out by physicists from the basic theory. I've just glanced at Brian Greene's "the Elegant Universe" where he describes string theory as being able to describe physical circumstances whereby the fabric of space can tear. The extrapolation is mathematical and so has potential to be a representation of reality, but equally may have no such representation. If there is no experimental basis for linking the mathematics of the actual string theory itself to physical reality then is this kind of "next level" extrapolation magical thinking? Or does the fact that formal rules of mathematics are used to produce such extrapolation make it much firmer than this?