Again, all of these interpretation are consistent with all available evidence, and all of them can reproduce the predictions of QM. QM therefore does not implies any one of them.
Fair enough. However, this can be said from any scientific theory that includes non-directly observable (by your sensory apparatus) entities. It isn't only the wavefunction that can be "unassumed" into becoming a useful formalism for practical calculation purposes but neither more nor less. You can do it to classical atoms, fields and molecules, up to and including the DNA, plus everything at the macroscopic scale that isn't a pure direct human experience. It's a philosophical position called Instrumentalism that certainly has its uses in times when the very meaning of those entities is under dispute, so it doesn't surprise that it gets adopted among so many QM physicists. The alternative of Realism, i.e. affirming the existence as is of those entities, is just... more interesting, I guess. And from what you summarize of the different positions it seems to me that MWI does indeed fit well into the position of baseline QM position. Everything else proposes that those entities aren't, or are but not quite, or almost are, or are in some other way than they seem to be etc., while MWI just takes things at face value and goes with them.
My, aren't we angry? Relax, man. Nothing in this conversation is going to change anything for anyone. I guess next we should start talking about Wolfgang Smith's anti-MWI, anti-Copenhagen, Catholic-Scholastic-Aristotelian-based interpretation of QM as describing the operations of form upon prime matter's pure potentiality so as to generate the first level of secondary matter. Also, God. Maybe that'll make you enjoy these unpretentious conversations more.:-)
Talking about how many difficulties one has to over come to come up with and/or use the concept of wavelength collapse asinine to anyone having actually applied it to problems where it makes a lot of things easier. (...) what you did teach yourself is still rather distant from the actual nuts and bolts of quantum mechanics.
And the fun thing about knowing the overall picture is reading an observation like the above and immediately associating it to those of pragmatic users of the easier Ptolemaic epicycles when confronted with the more difficult Copernican ones. So yeah, I don't doubt it makes things easier. But is it true, or at least "truer"?
You're not actually anywhere close to applying the Solomonoff definition by just assuming that wave function collapse is harder to program into a Turing machine than world line splitting, when neither is anywhere near the point of being described by a Turing machine.
You're making this more difficult than it needs to be. The collapse adds an extra "if" block:
if ( measurement ) {
for ( i = 0; i < probabilities; i++ ) {
if ( i != measurement ) {
drop( &state[i] );
}
} }
Nope, autodidact here. My formal training is in Philosophy of Science: deduction, induction, falsifiability, reductionism, different formal logics etc. The tool set all hard sciences use.
You conveniently left out the other half, that someone starting from QM alone could not assume MWI because it appears unneeded and conclude, "Oh, this implies there is wavefunction collapse."
Them that someone has to deal with that list of 8 difficulties, and solve each one.
those pushing for other interpretations are just as convinced the concept of splitting worlds and the postulated existence of multiple worlds makes Many-Worlds the more complex one
I'm using a somewhat precise definition of complexity, based on Solomonoff. If others see differently then either they're using another definition, or one of us is mistaken on how we use the concept. Let's suppose it's the former. What's the formal definition of complexity they're using?
But they are assumptions. MW asserts that all the other realities we don't observe (all the rest of the white noise) is part of ontological reality. And it doesn't present any evidence to justify that assertion. You may find it a plausible assumption, or a completely implausible one, but it certainly is an assumption.
I'd say it can be taken both ways. You can either start with QM alone and not assume the collapse postulate because it's unneeded, then conclude: "Oh, this implies there's a multiverse out there. Interesting." Or you can start assuming: "Hey, a multiverse existing is neat, let me search a sciencey-something that supports it!" and arrive at Many-Worlds because it provides you the conclusion you already wanted. The first one has no assumption other than "Let's see what the equations say when I don't artificially restrain them", while the second one is basically composed of assumption. So I guess it's a matter of checking with every MWI defender what he himself is going for.
Notice that the same can work in reverse for the Copenhagen interpretation. Someone who started from a collapse-less QM might well find the MWI implications abhorrent and seek something that'd make him comfortable with only one world existing. Yudkowsky has a small piece of fiction in which he imagines a world where MWI is dominant, taught in schools, and as a result religious-based "One Christer" political movements appear insisting that schools should "teach the controversy".:-)
You didn't provide any such algorithm here, you only assume that it would agree with your current views.
Because we're simplifying. But the idea is indeed simple. If I put the QM equations in a computer and make it run then in principle, given enough time, it should (at least it's expected) start showing galaxies, planets etc. Sure, a few pieces are still missing such as Quantum Gravity, but the gist of it is that the set of all fundamental laws of physics are the algorithm. So we have at least two candidates: one with this set of laws, and one that has this same set plus an additional one: the collapse postulate. So the question is: as far as what's observable goes, do they produce different results? If not, if the smaller set is enough, then why opt for the bigger set? Notice: "because of unobservable consequence x" shouldn't have weight either way.
In any case, thanks for the observations about size. I'll look further into it.
Instead of reading web pages from charlatans and uneducated non-physicists like Eliezer Yudkovski, you should read what actual physicists have to say about MW:
I don't think an article that makes analogies about Many-Worlds with political egalitarianism and inserts Hitler and Stalin in the mix should count as particularly well balanced, but I admit the text and the comments below it were quite very interesting, although not for the reasons you state, but because it shows a clear cut contemporaneous case of soft Instrumentalism. Soft because the author doesn't reach the more hardcore levels of refusing the reality of any theoretical entity, but when he reaches down far enough he stops and, as every classical Instrumentalist before him, on a variety of fields, says what basically amounts to: "these, they don't mean anything, they're just tools". In fact he says it many, many times, so I'll limit myself to show just four examples:
a) From the text: "Physics isn't obliged to answer physically meaningless questions and indeed, one may use quantum phenomena to show that all such questions whether "something was real before it was seen" are meaningless and can't have objective answers."
b) From an earlier comment: "(...) the wave function is not butter. It is not any other objectively real object, either. It is a collection of probability amplitudes and they have no other meaning than that they're building blocks in calculable probabilities."
c) From an intermediate comment: "You may mean many things by an 'idealist' but in all interpretations of the word, I may be classified as a 'proud idealist', not a closet one. (...) it's true that the only exact meaning of the wave function is a tool to encode all information about the subjective knowledge."
d) From a later comment: "Realism is an assumption that was true in classical physics - approximate theories used until the 19th century. This assumption was proved not to hold in this world in 1925-1926 and anyone who hasn't managed to notice yet is an imbecile."
Now, don't get me wrong. Instrumentalism has its purposes, one of which is relativising (in the sociological meaning of the word) competing explanations of the world when a single one hasn't yet become dominant so as to make everyone comfortable in openly discussing them. After all, those theories are "just" meaningless conceptualizing, mere "useful" tools in the toolset of those occupied with "real" world but not "actual" descriptions of reality.
However there always arrive a point when doing this stops being useful and a return to Realism becomes mandatory otherwise things don't advance. For at a later time, upon many conflicting new theoretical frameworks, Instrumentalism again returning in force.
And thus the pendulum swings.
Let's see how much time it takes for QM to complete the transition.
All arguments in favor of MW basically seem to come down to, "Assume standard QM is a complete and accurate description of reality, assume the wavefunction is the most fundamental ontological object, then remove the collapse of the wavefunction, and you're left with MW." Which isn't very convincing and involves a lot of unjustified assumptions.
I don't think they're assumptions really. Many-Worlds is understood by its defendants basically as the default option. Absent anything else, it's what everyone should take as their baseline, unless experimentally proven otherwise. Copenhagen happens to affirm that there's a something else, the collapse, so for "many-worlders" it's the obligation of "copenhagers" to show there's such an additional effect in reality, not for MW to show there isn't. Now, if some more complex interpretation has testable stuff, and it happens to be repeatedly tested and not-falsified, then sure, by all means let's adopt it. Until then however the baseline (and its logical consequences) should remain.
The problem with Occam's Razor in such situations, is that there is no objective definition of what "simpler" means.
Actually, there is. It's called Solomonoff's Induction", the mathematically formalized version of Occam's Razor. What it says in practical terms is roughly that you must be able to convert your competing hypotheses into their shortest algorithmic form runnable in a given Turing machine so that running all these algorithms will output that phenomenon. The simpler theory is the shortest of them all, measured in bits.
Notice that this formalization doesn't care on the size of the output, only that the algorithm is shorter and outputs the phenomenon. Copenhagen and Many-Worlds may both provide the same observed output, and Many-Worlds can have lots of additional output that Copenhagen doesn't have, but by being algorithmically shorter, literally equal to Copenhagen minus the collapse postulate, it "wins".
This is completely unrelated to different interpretations. QM, using any of the popular interpretations or not, allows entanglement and quantum effects on any scale and also can be reduced down to classical physics.
I don't know whether the Copenhagen interpretation has been updated to allow for superposition at macroscopic scales, but as far as I remember its defendants were very adamant in that at some scale the collapse caused all the weird quantum phenomena to disappear and classical physics to hold as something different from QM for everything above it. Has this changed?
That's a philosophical argument, one based on reductionism. Reductionism is no more provable physically than mathematics, logics or Occam's razor, but try doing science without any of them and I'll be pretty certain that you won't get far.
MW violate other physic principle anyway. Like parity.
I've replied to another post saying the same in this thread. But even if that's the case, it still violates much less pretty settled stuff than Copenhagen, and as such remains a superior, as in "Occam-simpler", alternative.
it seems to jump from "we don't understand uncertainty" to "let's explain why we can't understand it"
No, that's incorrect. Many-Worlds come from a simple realization: Quantum Mechanics works the same without the collapse postulate of the Copenhagen interpretation. So, by Occam's Razor, we take the simpler, collapse-less version, and see what it says, without prejudging. And what it says is this: there is no "size" above which entanglement ends and classical, non-QM physics begins. As such, the whole of QM, superposition include, also applies to the whole of the Universe. Hence, many-worlds superimposed. QED.
That science fiction predicted this, or before it religion (Hinduism and to a minor extent Buddhism both have the concept of infinite parallel worlds), has no weight on the matter. It's no more an argument against the Many-Worlds concept than the fact that the Ancient Greek thought of atoms would be an argument against the Standard Model.
Your link provides this objection but also the response: "The splitting is time asymmetric; this observed temporal asymmetry is due to the boundary conditions imposed by the Big Bang". Yudkowsky explains this in a comment in the thread in next paragraph's first link: "If you took one world and extrapolated backward, you'd get many pasts. If you take the many worlds and extrapolate backward, all but one of the resulting pasts will cancel out! Quantum mechanics is time-symmetric." (emphasis mine) So the violation is apparent. In fact, if the laws of physics lead to a Big Crunch, then the same cancellation happens forward in time, with alternate futures canceling out until only only one remains at the crunch point. As far as I know however the consensus seems to be that there won't be a Big Crunch, so the branching continues, perhaps without reality ever reaching a point were cancellations start occurring. Or not.
But the Less Wrong folk go further than Many-Worlds. They also consider Barbour's Timeless physics as most probably correct, what entirely removes time from the equation (literally as is the case). As such what we subjectively experience as time flow, time-dependent causality and entropy increasing, not to mention what we conceptually picture as universes branching, wouldn't be a proper description of what goes on at reality's base level. On the contrary, all states of reality, from the point of zero entropy / one world towards the other extreme of maximum entropy / whatever-worlds would form a static plenum, with causality reframed as a set of mathematical relations between static states.
So, no, not disingenuous at all. Maybe wrong, yes, but still a valid counterpoint.
It's the belief that we have no choice, make no choices
No, it's the "belief" that our choices are physics. No more and, most importantly and fundamental, no less. "Choice" is a function a physical brain executes upon physical information, it's the name we do to our subjective perception (another physical function) of our brain doing a bidirectional search between our set of initial conditions, the things we subjectively call "can", and our set of goals, the things we subjectively call "should". When paths between our several "cans" and "shoulds" are finds, we weight them and "chose" the one with the most weight.
So, yes, it's deterministic, but no, it is no less a choice that if we had that magic undefined and undefinable something people confusedly call "free will", which in turn, in fact and physically is but the fact of having a huge set of "cans" and "shoulds" and thus "choices".
That contradicts everything we know about human psychology,
No, it doesn't. What it contradicts are naive, unscientific "knowledges" of human psychology which every day gets more and more refuted by advances in evolutionary psychology, cognitive psychology and neuroscience.
as well as every possible evolutionary account for the advantage of consciousness. It contradicts evolution itself, since according to many worlds every possibility going forward is realized in one universe or another, even the possibilities which are, in a Darwinian sense, less fit.
Also no. Unfit species continue being non-viable no matter how many branches exist. The process of natural selection doesn't stop working just because you have an infinite set of parallel universes. It'll still happen in all of them.
In fact, many-world is one of the most powerful arguments against creationist arguments based on the "improbability" of consciousness appearing "by pure randomness". If you have infinite parallel universes going through natural selection, yes, you'll have infinitely many where life never emerged, infinitely many where it never reached the unicellular stage, infinitely many where it never reached the multicellular stage, and so on and so forth up to infinitely many where it never reached consciousness, but also infinitely many where all the selective pressures aligned just so as to allow cognition to conscience to emerge. We, being born in one of such universes, are lucky enough to be able to look back and find ourselves developing in a mere 4 billion or so years of nice events that lead to us, but that's neither exceptional nor rare, because any probability, infinitesimal as it might be provided it isn't 0, when multiplied by infinity becomes 1.0 and is guaranteed to happen somewhere, infinitely many times.
But even if your interpretation was correct, it would be meaningless. Science is reductionist. Natural selection is a by-product of more fundamental laws. If those laws were to state that some universes are, so to speak, "gentler" and hence allowing for less fit species to thrive despite the odds, then in those universes you'd have a slightly different high level law in place of natural selection, which maybe included "our" natural selection as a special case. But that's neither here nor there. The multiverse we and our future branchings live in isn't of the gentler kind, so let's focus on things as they actually are and on how we can improve them starting from where we in fact are. That's all the "choice" we have, and it's plenty, for infinitely many universes depend on it.:-)
If collapse actually worked the way its adherents say it does, it would be:
1. The only non-linear evolution in all of quantum mechanics. 2. The only non-unitary evolution in all of quantum mechanics. 3. The only non-differentiable (in fact, discontinuous) phenomenon in all of quantum mechanics. 4. The only phenomenon in all of quantum mechanics that is non-local in the configuration space. 5. The only phenomenon in all of physics that violates CPT symmetry. 6. The only phenomenon in all of physics that violates Liouville's Theorem (has a many-to-one mapping from initial conditions to outcomes). 7. The only phenomenon in all of physics that is acausal / non-deterministic / inherently random. 8. The only phenomenon in all of physics that is non-local in spacetime and propagates an influence faster than light.
Given the above considerations, whatever the experiment detected is most certainly not collapse.
Not quite an adherent, but thankful to them for having turned me towards materialism and atheism. But in regards to the quotes I'd suggest you read the texts linked. Any conclusion to a complex deduction will seem weird if it: a) doesn't fit nicely with the current common sense; b) you don't follow the reasoning that lead to it. I have my own criticisms of the Less Wrong community in general and Yudkowsky in particular, but I arrived at them after reading the whole thing, and they go beyond what's in that list mind you.:-)
As for the math, maybe, but I'll reserve any judgment until someone actually shows some actual problem.
I notice that you haven't addressed that article's use of statements of probability, despite me drawing specific attention to it.
There are two ways in which probabilities are talked about in that site. One is as Bayesian probability, which is a statement about our subjective ignorance (Bayesian probability is the general mathematical framework of which the scientific method, including falseabilism, Occam's Razor etc. are specific applications). Another, this one directly related to QM-proper, is as a distribution of branching worlds within the Many-Worlds interpretation. In this the "probabilities" are a description of the way the system spreads over different worlds, entangling in very predictable ways with the gigantic entangled system that are you and the even more gigantic entangled system that is the branch of reality you occupy. See the Decoherence post and the ones linked from it for details, although, as I said before, it's better to read the whole thing in sequence.
If collapse actually worked the way its adherents say it does, it would be:
1. The only non-linear evolution in all of quantum mechanics. 2. The only non-unitary evolution in all of quantum mechanics. 3. The only non-differentiable (in fact, discontinuous) phenomenon in all of quantum mechanics. 4. The only phenomenon in all of quantum mechanics that is non-local in the configuration space. 5. The only phenomenon in all of physics that violates CPT symmetry. 6. The only phenomenon in all of physics that violates Liouville's Theorem (has a many-to-one mapping from initial conditions to outcomes). 7. The only phenomenon in all of physics that is acausal / non-deterministic / inherently random. 8. The only phenomenon in all of physics that is non-local in spacetime and propagates an influence faster than light.
WHAT DOES THE GOD-DAMNED COLLAPSE POSTULATE HAVE TO DO FOR PHYSICISTS TO REJECT IT? KILL A GOD-DAMNED PUPPY?
And, for an even more humorous take on the subject, see this small fictional piece by him: If Many-Worlds Had Come First.
And the *physical* meaning of that is? / (...) that really doesn't buy it in something that's supposed to be explicatory.
That's the physical meaning. The whole series of texts has a simple purpose: to teach Quantum Mechanics from the simple perspective that it is what it is, without any appeal to naive "common sensical" attempts to interpret what actually goes on down there through the lens of evolutionarily conditioned subjective ways of perception whole purpose isn't apprehending reality as it is, but barely enough of it as to avoid dangers and to pursue reproductive opportunities. As such you won't find in it almost any comparison to waves, balls or the like, but rather the much simpler explanation that goes like this: "here's a particle, this is what it is, this is how it works, and please stop trying to think of if it as if it were what it isn't, or as if it did what it doesn't, or as if it didn't do what it does". Once one overcomes that subjective need of associating Quantum phenomena to some or all of those things we (partially and most of the time incorrectly) notice about the world, it starts being what it always was: simple, intuitive, deterministic and most definitely non-magical.
I think your best bet is to click the link to the TOC to the sequence of texts and read them in order. Once you reach the conclusion (namely: Everett's Many-Worlds couped Barbour's Timelessness) you'll see QM stopping being mysterious and stopping to be in need of further "meanings" beyond those it already has, and thus very differently from what happens with those who adopt the older, Occam-weak and most certainly incorrect Copenhagen interpretation.
Shit, you may have just given me the plot of a new sci-fi book (I'm working on "Whores In Space" right now).
LOL, glad to be of help!:-)
By the way, the part about cryo-preservation was factual. If you haven't signed for it maybe you still can. See here for details. I myself don't because I cannot, it isn't available here in Brazil (that I know), but if I lived where it is available I'd have signed for it long ago, and I still hope I'll be able to.
Slashdot Mirror
Again, all of these interpretation are consistent with all available evidence, and all of them can reproduce the predictions of QM. QM therefore does not implies any one of them.
Fair enough. However, this can be said from any scientific theory that includes non-directly observable (by your sensory apparatus) entities. It isn't only the wavefunction that can be "unassumed" into becoming a useful formalism for practical calculation purposes but neither more nor less. You can do it to classical atoms, fields and molecules, up to and including the DNA, plus everything at the macroscopic scale that isn't a pure direct human experience. It's a philosophical position called Instrumentalism that certainly has its uses in times when the very meaning of those entities is under dispute, so it doesn't surprise that it gets adopted among so many QM physicists. The alternative of Realism, i.e. affirming the existence as is of those entities, is just... more interesting, I guess. And from what you summarize of the different positions it seems to me that MWI does indeed fit well into the position of baseline QM position. Everything else proposes that those entities aren't, or are but not quite, or almost are, or are in some other way than they seem to be etc., while MWI just takes things at face value and goes with them.
My, aren't we angry? Relax, man. Nothing in this conversation is going to change anything for anyone. I guess next we should start talking about Wolfgang Smith's anti-MWI, anti-Copenhagen, Catholic-Scholastic-Aristotelian-based interpretation of QM as describing the operations of form upon prime matter's pure potentiality so as to generate the first level of secondary matter. Also, God. Maybe that'll make you enjoy these unpretentious conversations more. :-)
Talking about how many difficulties one has to over come to come up with and/or use the concept of wavelength collapse asinine to anyone having actually applied it to problems where it makes a lot of things easier. (...) what you did teach yourself is still rather distant from the actual nuts and bolts of quantum mechanics.
And the fun thing about knowing the overall picture is reading an observation like the above and immediately associating it to those of pragmatic users of the easier Ptolemaic epicycles when confronted with the more difficult Copernican ones. So yeah, I don't doubt it makes things easier. But is it true, or at least "truer"?
Beware the instrumentalist trap.
You're not actually anywhere close to applying the Solomonoff definition by just assuming that wave function collapse is harder to program into a Turing machine than world line splitting, when neither is anywhere near the point of being described by a Turing machine.
You're making this more difficult than it needs to be. The collapse adds an extra "if" block:
Nope, autodidact here. My formal training is in Philosophy of Science: deduction, induction, falsifiability, reductionism, different formal logics etc. The tool set all hard sciences use.
You conveniently left out the other half, that someone starting from QM alone could not assume MWI because it appears unneeded and conclude, "Oh, this implies there is wavefunction collapse."
Them that someone has to deal with that list of 8 difficulties, and solve each one.
those pushing for other interpretations are just as convinced the concept of splitting worlds and the postulated existence of multiple worlds makes Many-Worlds the more complex one
I'm using a somewhat precise definition of complexity, based on Solomonoff. If others see differently then either they're using another definition, or one of us is mistaken on how we use the concept. Let's suppose it's the former. What's the formal definition of complexity they're using?
Many worlds is just one way to resolve the problem. There are others one that do effectively, without resorting to consciousness
Thanks, I've added them to my reading queue.
But they are assumptions. MW asserts that all the other realities we don't observe (all the rest of the white noise) is part of ontological reality. And it doesn't present any evidence to justify that assertion. You may find it a plausible assumption, or a completely implausible one, but it certainly is an assumption.
I'd say it can be taken both ways. You can either start with QM alone and not assume the collapse postulate because it's unneeded, then conclude: "Oh, this implies there's a multiverse out there. Interesting." Or you can start assuming: "Hey, a multiverse existing is neat, let me search a sciencey-something that supports it!" and arrive at Many-Worlds because it provides you the conclusion you already wanted. The first one has no assumption other than "Let's see what the equations say when I don't artificially restrain them", while the second one is basically composed of assumption. So I guess it's a matter of checking with every MWI defender what he himself is going for.
Notice that the same can work in reverse for the Copenhagen interpretation. Someone who started from a collapse-less QM might well find the MWI implications abhorrent and seek something that'd make him comfortable with only one world existing. Yudkowsky has a small piece of fiction in which he imagines a world where MWI is dominant, taught in schools, and as a result religious-based "One Christer" political movements appear insisting that schools should "teach the controversy". :-)
You didn't provide any such algorithm here, you only assume that it would agree with your current views.
Because we're simplifying. But the idea is indeed simple. If I put the QM equations in a computer and make it run then in principle, given enough time, it should (at least it's expected) start showing galaxies, planets etc. Sure, a few pieces are still missing such as Quantum Gravity, but the gist of it is that the set of all fundamental laws of physics are the algorithm. So we have at least two candidates: one with this set of laws, and one that has this same set plus an additional one: the collapse postulate. So the question is: as far as what's observable goes, do they produce different results? If not, if the smaller set is enough, then why opt for the bigger set? Notice: "because of unobservable consequence x" shouldn't have weight either way.
In any case, thanks for the observations about size. I'll look further into it.
Instead of reading web pages from charlatans and uneducated non-physicists like Eliezer Yudkovski, you should read what actual physicists have to say about MW:
I don't think an article that makes analogies about Many-Worlds with political egalitarianism and inserts Hitler and Stalin in the mix should count as particularly well balanced, but I admit the text and the comments below it were quite very interesting, although not for the reasons you state, but because it shows a clear cut contemporaneous case of soft Instrumentalism. Soft because the author doesn't reach the more hardcore levels of refusing the reality of any theoretical entity, but when he reaches down far enough he stops and, as every classical Instrumentalist before him, on a variety of fields, says what basically amounts to: "these, they don't mean anything, they're just tools". In fact he says it many, many times, so I'll limit myself to show just four examples:
a) From the text: "Physics isn't obliged to answer physically meaningless questions and indeed, one may use quantum phenomena to show that all such questions whether "something was real before it was seen" are meaningless and can't have objective answers."
b) From an earlier comment: "(...) the wave function is not butter. It is not any other objectively real object, either. It is a collection of probability amplitudes and they have no other meaning than that they're building blocks in calculable probabilities."
c) From an intermediate comment: "You may mean many things by an 'idealist' but in all interpretations of the word, I may be classified as a 'proud idealist', not a closet one. (...) it's true that the only exact meaning of the wave function is a tool to encode all information about the subjective knowledge."
d) From a later comment: "Realism is an assumption that was true in classical physics - approximate theories used until the 19th century. This assumption was proved not to hold in this world in 1925-1926 and anyone who hasn't managed to notice yet is an imbecile."
Osiander would approve. :-)
Now, don't get me wrong. Instrumentalism has its purposes, one of which is relativising (in the sociological meaning of the word) competing explanations of the world when a single one hasn't yet become dominant so as to make everyone comfortable in openly discussing them. After all, those theories are "just" meaningless conceptualizing, mere "useful" tools in the toolset of those occupied with "real" world but not "actual" descriptions of reality.
However there always arrive a point when doing this stops being useful and a return to Realism becomes mandatory otherwise things don't advance. For at a later time, upon many conflicting new theoretical frameworks, Instrumentalism again returning in force.
And thus the pendulum swings.
Let's see how much time it takes for QM to complete the transition.
All arguments in favor of MW basically seem to come down to, "Assume standard QM is a complete and accurate description of reality, assume the wavefunction is the most fundamental ontological object, then remove the collapse of the wavefunction, and you're left with MW." Which isn't very convincing and involves a lot of unjustified assumptions.
I don't think they're assumptions really. Many-Worlds is understood by its defendants basically as the default option. Absent anything else, it's what everyone should take as their baseline, unless experimentally proven otherwise. Copenhagen happens to affirm that there's a something else, the collapse, so for "many-worlders" it's the obligation of "copenhagers" to show there's such an additional effect in reality, not for MW to show there isn't. Now, if some more complex interpretation has testable stuff, and it happens to be repeatedly tested and not-falsified, then sure, by all means let's adopt it. Until then however the baseline (and its logical consequences) should remain.
The problem with Occam's Razor in such situations, is that there is no objective definition of what "simpler" means.
Actually, there is. It's called Solomonoff's Induction", the mathematically formalized version of Occam's Razor. What it says in practical terms is roughly that you must be able to convert your competing hypotheses into their shortest algorithmic form runnable in a given Turing machine so that running all these algorithms will output that phenomenon. The simpler theory is the shortest of them all, measured in bits.
Notice that this formalization doesn't care on the size of the output, only that the algorithm is shorter and outputs the phenomenon. Copenhagen and Many-Worlds may both provide the same observed output, and Many-Worlds can have lots of additional output that Copenhagen doesn't have, but by being algorithmically shorter, literally equal to Copenhagen minus the collapse postulate, it "wins".
This is completely unrelated to different interpretations. QM, using any of the popular interpretations or not, allows entanglement and quantum effects on any scale and also can be reduced down to classical physics.
I don't know whether the Copenhagen interpretation has been updated to allow for superposition at macroscopic scales, but as far as I remember its defendants were very adamant in that at some scale the collapse caused all the weird quantum phenomena to disappear and classical physics to hold as something different from QM for everything above it. Has this changed?
That's a fallacy, not a physic argument.
That's a philosophical argument, one based on reductionism. Reductionism is no more provable physically than mathematics, logics or Occam's razor, but try doing science without any of them and I'll be pretty certain that you won't get far.
MW violate other physic principle anyway. Like parity.
I've replied to another post saying the same in this thread. But even if that's the case, it still violates much less pretty settled stuff than Copenhagen, and as such remains a superior, as in "Occam-simpler", alternative.
it seems to jump from "we don't understand uncertainty" to "let's explain why we can't understand it"
No, that's incorrect. Many-Worlds come from a simple realization: Quantum Mechanics works the same without the collapse postulate of the Copenhagen interpretation. So, by Occam's Razor, we take the simpler, collapse-less version, and see what it says, without prejudging. And what it says is this: there is no "size" above which entanglement ends and classical, non-QM physics begins. As such, the whole of QM, superposition include, also applies to the whole of the Universe. Hence, many-worlds superimposed. QED.
That science fiction predicted this, or before it religion (Hinduism and to a minor extent Buddhism both have the concept of infinite parallel worlds), has no weight on the matter. It's no more an argument against the Many-Worlds concept than the fact that the Ancient Greek thought of atoms would be an argument against the Standard Model.
Actually, many worlds violates CPT symmetry - worldlines divide only forward in time, not backwards.
Your link provides this objection but also the response: "The splitting is time asymmetric; this observed temporal asymmetry is due to the boundary conditions imposed by the Big Bang". Yudkowsky explains this in a comment in the thread in next paragraph's first link: "If you took one world and extrapolated backward, you'd get many pasts. If you take the many worlds and extrapolate backward, all but one of the resulting pasts will cancel out! Quantum mechanics is time-symmetric." (emphasis mine) So the violation is apparent. In fact, if the laws of physics lead to a Big Crunch, then the same cancellation happens forward in time, with alternate futures canceling out until only only one remains at the crunch point. As far as I know however the consensus seems to be that there won't be a Big Crunch, so the branching continues, perhaps without reality ever reaching a point were cancellations start occurring. Or not.
But the Less Wrong folk go further than Many-Worlds. They also consider Barbour's Timeless physics as most probably correct, what entirely removes time from the equation (literally as is the case). As such what we subjectively experience as time flow, time-dependent causality and entropy increasing, not to mention what we conceptually picture as universes branching, wouldn't be a proper description of what goes on at reality's base level. On the contrary, all states of reality, from the point of zero entropy / one world towards the other extreme of maximum entropy / whatever-worlds would form a static plenum, with causality reframed as a set of mathematical relations between static states.
So, no, not disingenuous at all. Maybe wrong, yes, but still a valid counterpoint.
Edits: that -> than; finds -> found; gets -> get etc. Lack of editing, the bane of ./ ... :-(
It's the belief that we have no choice, make no choices
No, it's the "belief" that our choices are physics. No more and, most importantly and fundamental, no less. "Choice" is a function a physical brain executes upon physical information, it's the name we do to our subjective perception (another physical function) of our brain doing a bidirectional search between our set of initial conditions, the things we subjectively call "can", and our set of goals, the things we subjectively call "should". When paths between our several "cans" and "shoulds" are finds, we weight them and "chose" the one with the most weight.
So, yes, it's deterministic, but no, it is no less a choice that if we had that magic undefined and undefinable something people confusedly call "free will", which in turn, in fact and physically is but the fact of having a huge set of "cans" and "shoulds" and thus "choices".
That contradicts everything we know about human psychology,
No, it doesn't. What it contradicts are naive, unscientific "knowledges" of human psychology which every day gets more and more refuted by advances in evolutionary psychology, cognitive psychology and neuroscience.
as well as every possible evolutionary account for the advantage of consciousness. It contradicts evolution itself, since according to many worlds every possibility going forward is realized in one universe or another, even the possibilities which are, in a Darwinian sense, less fit.
Also no. Unfit species continue being non-viable no matter how many branches exist. The process of natural selection doesn't stop working just because you have an infinite set of parallel universes. It'll still happen in all of them.
In fact, many-world is one of the most powerful arguments against creationist arguments based on the "improbability" of consciousness appearing "by pure randomness". If you have infinite parallel universes going through natural selection, yes, you'll have infinitely many where life never emerged, infinitely many where it never reached the unicellular stage, infinitely many where it never reached the multicellular stage, and so on and so forth up to infinitely many where it never reached consciousness, but also infinitely many where all the selective pressures aligned just so as to allow cognition to conscience to emerge. We, being born in one of such universes, are lucky enough to be able to look back and find ourselves developing in a mere 4 billion or so years of nice events that lead to us, but that's neither exceptional nor rare, because any probability, infinitesimal as it might be provided it isn't 0, when multiplied by infinity becomes 1.0 and is guaranteed to happen somewhere, infinitely many times.
But even if your interpretation was correct, it would be meaningless. Science is reductionist. Natural selection is a by-product of more fundamental laws. If those laws were to state that some universes are, so to speak, "gentler" and hence allowing for less fit species to thrive despite the odds, then in those universes you'd have a slightly different high level law in place of natural selection, which maybe included "our" natural selection as a special case. But that's neither here nor there. The multiverse we and our future branchings live in isn't of the gentler kind, so let's focus on things as they actually are and on how we can improve them starting from where we in fact are. That's all the "choice" we have, and it's plenty, for infinitely many universes depend on it. :-)
the 'conciousness' part of Copenhagen is an anthropic bias
It's worse than that. According to defenders of the Many-Worlds interpretation (of which I consider myself one), Copenhagen's collapse has several problems. Less Wrong's Eliezer Yudkowsky has written an extensive introduction to QM from the perspective of the Many-Worlds Interpretation and as part of the series he's extensively criticized the collapse postulate, summarizing its problems thus:
Given the above considerations, whatever the experiment detected is most certainly not collapse.
Not quite an adherent, but thankful to them for having turned me towards materialism and atheism. But in regards to the quotes I'd suggest you read the texts linked. Any conclusion to a complex deduction will seem weird if it: a) doesn't fit nicely with the current common sense; b) you don't follow the reasoning that lead to it. I have my own criticisms of the Less Wrong community in general and Yudkowsky in particular, but I arrived at them after reading the whole thing, and they go beyond what's in that list mind you. :-)
As for the math, maybe, but I'll reserve any judgment until someone actually shows some actual problem.
I notice that you haven't addressed that article's use of statements of probability, despite me drawing specific attention to it.
There are two ways in which probabilities are talked about in that site. One is as Bayesian probability, which is a statement about our subjective ignorance (Bayesian probability is the general mathematical framework of which the scientific method, including falseabilism, Occam's Razor etc. are specific applications). Another, this one directly related to QM-proper, is as a distribution of branching worlds within the Many-Worlds interpretation. In this the "probabilities" are a description of the way the system spreads over different worlds, entangling in very predictable ways with the gigantic entangled system that are you and the even more gigantic entangled system that is the branch of reality you occupy. See the Decoherence post and the ones linked from it for details, although, as I said before, it's better to read the whole thing in sequence.
As for Copenhagen, here's how the author of describes the issues with believing in the collapse postulate:
And, for an even more humorous take on the subject, see this small fictional piece by him: If Many-Worlds Had Come First.
Edit: "couped" -> "coupled with".
And the *physical* meaning of that is? / (...) that really doesn't buy it in something that's supposed to be explicatory.
That's the physical meaning. The whole series of texts has a simple purpose: to teach Quantum Mechanics from the simple perspective that it is what it is, without any appeal to naive "common sensical" attempts to interpret what actually goes on down there through the lens of evolutionarily conditioned subjective ways of perception whole purpose isn't apprehending reality as it is, but barely enough of it as to avoid dangers and to pursue reproductive opportunities. As such you won't find in it almost any comparison to waves, balls or the like, but rather the much simpler explanation that goes like this: "here's a particle, this is what it is, this is how it works, and please stop trying to think of if it as if it were what it isn't, or as if it did what it doesn't, or as if it didn't do what it does". Once one overcomes that subjective need of associating Quantum phenomena to some or all of those things we (partially and most of the time incorrectly) notice about the world, it starts being what it always was: simple, intuitive, deterministic and most definitely non-magical.
I think your best bet is to click the link to the TOC to the sequence of texts and read them in order. Once you reach the conclusion (namely: Everett's Many-Worlds couped Barbour's Timelessness) you'll see QM stopping being mysterious and stopping to be in need of further "meanings" beyond those it already has, and thus very differently from what happens with those who adopt the older, Occam-weak and most certainly incorrect Copenhagen interpretation.
Shit, you may have just given me the plot of a new sci-fi book (I'm working on "Whores In Space" right now).
LOL, glad to be of help! :-)
By the way, the part about cryo-preservation was factual. If you haven't signed for it maybe you still can. See here for details. I myself don't because I cannot, it isn't available here in Brazil (that I know), but if I lived where it is available I'd have signed for it long ago, and I still hope I'll be able to.
What to you is the physical meaning of the "amplitudes"?
Configurations and Amplitude