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Comment by dbvdh | Hacker News Reader

"This rather fanciful interpretation of Quantum Physics has now become accepted by many theoretical physicists as being more satisfactory than the Copenhagen interpretation, despite the fact that the mechanism which causes the splitting of the Universe is not explained in any more detail than wavefunction collapse. As you can probably tell, I am in the minority of physicists who finds the Many Worlds interpretation dificult to accept, and not particularly illuminating."

I think these lectures are a good intro to QM. This statement feels very emotional though. Many-worlds just states there is no such thing as wave function collapse. The many worlds are a logical conclusion following. Copenhagen simply refuses to elaborate to when wave-function collapse happens, which to me is not a complete theory.

You could have some critique of many-worlds in relation to statistics, although I think many people have given quite satisfactory explanations.

Many worlds is just bare bones QM.. If any other theory is proposed, it should be falsifiable (like pilot wave theory for example). Doesn't mean it won't be difficult to measure.

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FWIW (and it's not worth a lot, since I'm a layperson), I think the interpretation that makes the most sense to me is Quantum Decoherence (https://en.wikipedia.org/wiki/Quantum_decoherence).

My interpretation of the interpretation is that the universe is a giant constraint resolution system. Particles are free to be anywhere randomly as long as they do not randomly interact with other particles. As soon as they interact they have fewer "degrees of freedom", since now they interacted. When they interact with anything macroscopic they have no freedom left. Makes sense to me anyway.

Decoherence only hides entanglement by having the entire world go into a complex superposition. It's entirely compatible with MWI. Decoherence does not resolve the measurement problem on its own. It's not a separate interpretation. It only provides us a mathematical reason for why the world appears classical.

Specifically, decoherence provides a mathematical reason why we don't see self-interference and similar quantum phenomena on classical objects. It doesn't on its own explain why the single classical world arises from the infinitely many solution pairs to any quantum equation.

Decoherence is how you get from "Maybe the wave function never collapses" to "Maybe there are many parallel 'universes' in QM.".

Decoherence gets you a diagonal density matrix description of the world. It doesn't get you a single-state description of the world. Going from "There are many parallel universes" to "and we are in one of them" still takes a lot of handwaving.

But we're not in one of them. We're in all of them. Yours is a misunderstanding of how it feels to be in a quantum superposition. There's no component of the wave function in which Schrodinger's cat experiences anything other than being alive or being dead. There's no component in which it feels like it's in some ghostly combination of both outcomes. Both components of the wave function exist in superposition, and to the extent that they are decoherent, they do not interact and do not even notice that they have company. I don't mean this only as an academic statement; it's also true of you and me, at this very moment.

There's the handwaving.

If that isn't absurd, then I don't know what is.

I think the alternatives would be more absurd:

- That humans can't be put into quantum superpositions, or

- That a human being in a quantum superposition of two states A and B would feel at all to that human like being in a quantum superposition of two states A and B, when neither of those states is "a human feeling like they're in a superposition of two states A and B".

Follow this to its conclusion, and you end up with a superposition of A and B meaning: "the universe is in a superposition, containing a component where a human believes that they're in state A, and a component where a human believes that they're in state B. Within both branches, the human thinks their wavefunction collapsed in that state". This is exactly the way that all interpretations of QM already understand things to work with particles in superpositions.

It's a bit like:

"Doc, I feel pain in my toe."

"No, sorry, the math says you don't."

"Okay, but like... I do."

"Sorry, you're just not good at accepting math!"

Not a perfect analogy, of course, but people have competing intuitions of what to do when the map fails to match the territory. MWI abandons the latter, most prefer the former.

Every state is a superposition. Even eigenstates (of some operator, e.g. X) are superpositions (of eigenstates of some other operator, e.g. P). So everything is a superposition and being superposition or not is relative.

> There's no component of the wave function in which Schrodinger's cat experiences anything other than being alive or being dead.

The problem is that this is not what Schrodinger predicts, though. If |alive> and |dead> are valid solutions to the Schrodinger equation of some system, then so is any linear combination of them whose norm is one, such as 1/sqrt(2) |alive> + 1/sqrt(2) |dead>. So the math of QM predicts that there should be infinitely many cats that should feel partly alive and partly dead, many times more than the one live cat and the one dead cat. And yet you don't find this in any classical experiment.

Maybe I have to say it again.

1/sqrt(2) |alive> + 1/sqrt(2) |dead> is a valid solution to the Schrodinger equation. That cat is half alive and half dead.

That is different than |A cat that feels half alive and half dead>, which is its own completely different state. For a cat to feel like it is half alive and dead, or to notice that it is half alive and half dead, there are distinct things that happening in its brain that don't happen in either the |alive> or |dead> basis vectors, let alone any linear combination of the two.

We could even put all those states in a superposition!

1/sqrt(3) |alive> + 1/sqrt(3) |dead> + 1/sqrt(3) |half alive and half dead>.

But you can pick those other values as basis vectors, and they are just as good a choice as alive/dead. The only reason that you can say "the cat's brain doesn't experience those other states" is that you've presupposed a classical cat, that has some preferred basis. But this is just begging the question. We only get classical behavior when the wavefunction gets entangled with a classical object, but the math predicts you should also have non-classical "half-here" objects that would experience non-classical "half states" - and those are actually infinitely many.

So how did the classical world arise? Or how come we happen to be in the classical world, when there are infinitely many other non-classical observers? And note that the anthropic principle doesn't help here - all of the real laws of physics are the same for those other observers, you get the same chemistry etc, it's just the classical approximations that fail.

Decoherence isn't an interpretation, but an experimentally established fact. What makes interpretations interpretations is that they cannot be experimentally distinguished (or in some cases, can only be with great difficulty). That said, the study of decoherence has certainly made aspects of the measurement problem easier to come to terms with, which in turn has bearing on the intuitive draw of some interpretations over others. In particular, it helps answer when universes should be said to "split" in MWI (though, as many will rightly tell you, that's not a complete solution to the measurement problem, as decoherence is still unitary--i.e., there's no in-principle irreversibility there).

Many-worlds is an interpretation and not a theory. It makes no additional predictions beyond what QM does. Believing in any interpretation (or shutting up and calculating) is purely emotional; it has no scientific content.

(Disclaimer: I'm nowhere near truly knowledgeable about any of this)

Quantum computing was explicitly proposed as a way to prove the truth of many worlds. As far as we can tell, quantum computing appears to work.

I don't think most people believe QC truly proves many-worlds, but I think it is considered some evidence in its favor, and historically it was I think one of the reasons for the development of QC originally.

I've heard this claim, but I don't think it holds up. The idea is that supposedly the calculation is done in parallel across the different universes which allows you to see an exponential speedup in some calculations. But the whole point of many-worlds is that after a branch event the various branched portions of the wavefunction no longer interact. Even if it were true that quantum computing was really a bunch of parallel classical computations (which it is not), there would be no way for any of the other universes to communicate the result back to the universe you observe it in.

Many worlds doesn't really feature 'hard branches'. In fact the interpretation is pretty specific that quantum interactions becoming de-correlated and stopping to react is the mechanism by which you get the 'many worlds', and this is a soft and messy process not some global hard split.

OTOH, I don't think any of the other interpretations really struggle to explain quantum computing so I agree it's not much of a distinguishing factor.

I don't think there is anything in quantum computing that is specific yo the many worlds interpretation.

But if what you want is understanding, you want a good explanation. (Or to quote TheOtherHobbes from elsewhere in these comments, a reasonable metaphor: https://news.ycombinator.com/item?id=50220700)

If you only like predictions and disparage explanations, I might start calling you names, specifically instrumentalist.

What do call someone who wants good "Just So" story explanations that don't explain anything, but posit the existence of meaningless things?

Here you are taking "good explanation" and combining it with the term "just so story" which indicates a bad (arbitrary) explanation. So you cast doubt on the idea that explanations can be good. What's this, sabotage?

It has mathematical and philosophical content. People can be convinced for reasons other than empirical without it being emotional. Sean Carroll makes logical arguments for why he's convinced MWI is correct.

I'm not Sean Carroll. I'm interested in logical arguments for why I should be convinced that something completely impossible to ever test, not even in theory, is correct.

How do you test whether the dinosaurs once existed as living animals, vs as fossils that were embedded in the Earth when the universe began 6000 years ago?

Because I only believe one of these propositions, even though I can't imagine any test that would discriminate between the two.

Sure you can. There is no predictability and no fundamental laws in a purpose-built universe run by an omnipotent creator because ultimately the creator can do anything they please.

Not to get all reddit atheist here, but as far as we can tell, the universe is predictable and explainable by fundamental mathematical laws. (We don't see, for example, unexplainable violations of conservation as Michael Landon pops in and out of existence.)

This could mean there is no god or they don't interfere or whatever, but in any case it's pretty good evidence that we can reason about how the universe works.

That's about as good as you can know anything. Beyond that is the "Are you a brain in a jar" kinds of philosophical arguments that are fun when you're 21 and get old after.

...uh, by using the abundant evidence from radiometric dating, geology and archeology that the world is much older than 6000 years old?

Plus astronomical observations used in cosmology to model the state of the universe milliseconds after the big bang which eventually evolved into our locally observable region of space around 13.8 billion (not 6000) years later?

That doesn't prove the dinosaurs were in fact living beings but this isn't necessary to disprove the other assumptions of the alternative hypothesis. By parsimony that leaves the hypothesis that dinosaur fossils emerged by natural processes like everything else we've observed on Earth to date.

Am I missing a joke? Because this is definitely not a good example of a hypothesis impossible to disprove with available evidence.

(If the response is "how do you test whether all that evidence was faked 6000 of years ago to deceive scientists" then we're not actually doing science anymore but games of make believe)

That's exactly what we're doing. Obviously I don't believe the initial conditions of the universe were set 6000 years ago, and just look billions of years older by mere coincidence. My point -- directed at its parent comment -- is that we can scientifically prefer one hypothesis over the other, even though they're indistinguishable by any experiment because they make identical predictions.

Instead, we can use other forms of reasoning, such as probability and Ockham's razor. These are perfectly valid approaches.

You seem to agree with me on this point, so I direct your attention to the grandparent comment:

> I'm interested in logical arguments for why I should be convinced that something completely impossible to ever test, not even in theory, is correct.

This is the way! It is absolutely amazing that the supposedly "brilliant brains" at lesswrong and other similar outfits, have not learned about the difference between an interpretation and a theory.

Since QM goes beyond our material world intuitions, I am personally loathe to clothe nrs in words, until we have more and better experiments. I think prematurely translating it into material-level intuitions just leads to a waste of time and much confusion.

Does it not make any predictions? It states there is no such thing as wavefunction collapse. This means that if you entangle a state with a large system, in theory you could ‘disentangle’ it. Of course, this is no easy feat. But indeed quantum computing to me, is an example of this feat. We can entangle systems on a large scale, then use this feat to make calculations. Inspiration for quantum computing actually came from many worlds.

Many worlds is falsifiable, if you can show wave function collapse actually happens (not just decoherence). I believe that in the not so distant future we will get more and more proof that wave function collapse never happens. Quantum computing at scale to me is an indication that Everett was just right..

Nope it’s the opposite. The Copenhagen wavefunction collapse is untestable or unfalsifiable.

With many words, every postulate has been tested and very verified. What more can you ask from a theory?

Now objective collapse is a testable postulate but none expects that to pan out.

> This means that if you entangle a state with a large system, in theory you could ‘disentangle’ it.

This can be done in any other interpretation? Any unitary evolution on an isolated system can be reversed. This is a mathematical statement.

> Many worlds is falsifiable, if you can show wave function collapse actually happens

So, what experiments do you think would falsify it? How can you show that collapse actually happened?

In the Copenhagen interpretation, when I look at schrodingers cat, the wavefunction will collapse. After I have looked at it, no way to go back. Information is lost. In many worlds, I just become entangled with the system - and I could theoretically disentangle after. Like quantum computing going to a deterministic outcome in a certain basis.

Showing collapse happened is really tricky because of decoherence. Similar to unmixing coffee and milk. But all systems we have observed so far do not show wave function collapse (granted these systems are generally small, but otherwise decoherence starts messing about).

These are just fundamentally different theories. Not just an interpretation, physically different outcomes.

> In the Copenhagen interpretation, when I look at schrodingers cat, the wavefunction will collapse. After I have looked at it, no way to go back.

In the Copenhagen interpretation, there is a difference between measuring a system and entangling with it. There exists a unitary that entangles you with the cat, just like there exists a unitary that entangles the cat with the quantum device. By definition, unitary evolution is not a measurement in the Copenhagen interpretation.

> Showing collapse happened is really tricky because of decoherence. Similar to unmixing coffee and milk.

Unmixing would show the lack of collapse (in the specific case), though? To show collapse you'd need somehow experimentally prove that it is impossible to unmix. And to falsify collapse, you'd need to somehow experimentally prove that it is always possible to unmix. And if we go with your analogy, would you say the coffee with milk hasn't forgotten its initial state because it is technically possible to unmix them? Being able to manipulate the whole universe's wavefunction to unentangle particular subsystems is akin to having access to Maxwell's daemon, since decoherence increases entropy.

Pretty much all physics for since forever has been about the ontological explanation of what’s happening. If you don’t want to subscribe to an ontological interpretation then that’s something new and the opposite of how people have always done physics. It’s something that has only ever come about with qm.

In normal physics people often use occamz razor and subscribe to what the interpretation with the simplest postulates says.

So the reality is the opposite. You don’t like what the physics is saying so for emotional reasons you’ve come up with a completely new and novel framework to discount what the simplest set of equations is saying.

> You don’t like what the physics is saying so for emotional reasons you’ve come up with a completely new and novel framework to discount what the simplest set of equations is saying.

Nah, physics is not saying anything. I do physics because I enjoy discovering and modeling new phenomena. If someone wants to do philosophy and ask questions like "but what is __really__ happening when we measure an atom", it's his business, but I don't believe we'd be doing the same thing, because these questions are impossible to answer with empirical evidence and don't help us model reality in any way. I don't see any difference between QM interpretations; one of them might be "true"

Given we haven’t bridged quantum with gravity yet, my bet is the function collapses right at the boundary when gravity starts to play a meaningful role.

That’s a more physically plausible interpretation than ever “tick” of the universe actually creates infinitely more universes because every fundamental particle is quantum and each one is constantly interacting under the wave function every plank second. And the infinite number of possible events that a single particle would experience is multiplied by the joint combination of all particles in the entire universe. It doesn’t seem plausible.

How would you define exactly ‘when gravity starts playing a role’. It always plays a role, from photons to planets.

And on the ‘every tick creates more universes’: we are completely fine with superposition in nanoscopic systems. It’s just uneasy to follow that conclusion to the logical end. Just my two cents. I think just because the conclusion seems hard to grasp, the reasoning to get there is completely sound..

“Starts to play a role” means when the effect of gravity becomes significant to the quantum equations which currently don’t have any placeholder for gravity.

Just like Newton’s equations are accurate to describe gravity and motion but only because the full equations Einstein worked simplify to them at small speeds.

So similarly it would make more sense that quantum equations and relativity are two sides of the same coin and there’s some missing mathematical bridge where at small particle sizes it simplifies to quantum and at large particle scales gravity matters and we get Newton and then further relativity.

Using Occam’s razor that’s at least my prior vs some undefined mechanism of action where all possible interactions of every particle actually creates an infinite superposition of universes where that did happen and you get an infinite number of such superpositions ad infinitum. Much easier to believe the huge gaping hole between two very accurate theories explains how quantum mechanics turns into classical mechanics, especially since we know gravity exists, what it is, and quantum mechanics can’t explain gravity.

The place where quantum and gravitational effects are thought to become significant to one another is at energy levels that cannot be obtained in our experiments, either in the lab or through astronomical observation.

And so as a result there’s multiple worlds? That’s the simpler more testable prediction?

It's simple and elegant if you like it, overcomplicated if you don't.

Many worlds is a philosophical interpretation akin to god. It doesn’t add anything to our understanding and instead invokes some kind of supernatural untestable phenomenon.

The many worlds are a consequence, not a postulate. It is the Copenhagen interpretation that postulates that all branches but one disappear at measurement.

Both of them are interpretations. We have no reason to believe one over the other.

I'm just an old industrial physicist, but as I understand it, quantum gravity has yielded no testable predictions so far, and neither have multiple-worlds theories.

I never said anything about quantum gravity. String theory is also trying to bridge things. But many worlds is pointing to a gap in the math and claiming god. All I’m saying is we don’t have any model or math and many worlds is the more fantastical explanation.

This is more or less Roger Penrose's position: https://web.archive.org/web/20150327124054id_/http://image.s...

He argues that the wavefunction collapses on a timescale of h-bar / E_G, where E_G is the gravitational self-energy of the quantum system.

Didn’t know this but glad I’m in such distinguished company.

You haven't bridged. I have bridged. https://doi.org/10.5281/zenodo.18445925

The quantum world involves states that are a complex linear superposition of all possible states. It isn't just that the world bifurcates into one where the cat is |alive> or |dead>, but also all c1 |alive> + c2 |dead>, where c1^2+c2^2 = 1 and c1 and c2 are complex. The MWI has no explanation for how this other infinity of possible states disappears into just two states. You still wind up with the collapse of the wave function--involving a lot of hand-waving or appealing to some nebulous property of consciousness.

>The MWI has no explanation for how this other infinity of possible states disappears into just two states. You still wind up with the collapse of the wave function--involving a lot of hand-waving or appealing to some nebulous property of consciousness.

The real issue here is the preferred basis problem, not an infinity of worlds: a single state vector can be decomposed many ways, and the bare math doesn't say which decomposition counts as "the branches." Decoherence picks it out: once the cat is entangled with its environment, the alive/dead decomposition becomes effectively unique and stable, through ordinary unitary dynamics. No collapse, no consciousness (that's von Neumann–Wigner, not Everett). MWI does have an open problem, but it's a different one: the Born rule, i.e. why |c|^2 should count as probability when every branch is real. Also, the normalization is |c1|^2 + |c2|^2 = 1.

Sure, the MWI still has an open problem which is why it looks like there is a collapse of the wave function.

No, it explains that well enough, it just struggles to explain why you would expect to see the collapse with the probabilities that you do (though, to be fair, most other interpretations don't presume to explain this at all, it's just a rule. MWI just reframes it in a way that makes it odd that there is a rule).

AI comment

> The MWI has no explanation for how this other infinity of possible states disappears into just two states

They don't disappear. This is the entire point of MW.

When the future has multiple instances of you, it becomes problematic to define what the Born rule means.

For example, "Many Worlds, the Born Rule, and Self-Locating Uncertainty" notices that the rule doesn't mean anything, but it is rational to behave like it does. It's not a very satisfying position, I'd say.

Many worlds as real ontology are just as wild as saying their is a God. Physicists are thus making claims that just as wild as the theologians .. I find this fascinating.

Just like the AI nerds and the AGI singularity or Musk saying we are in simulation...

ie so many crazy ideas.. for the rationalist, its like being in an insane asylum and trusting one mental patient or another..

I suppose at some level its just not rational why we exist. We must accept some wild, fundamental metaphysical assumption

This has never not been true. There are always hand wavy axioms at the bottom.

I think a common mistake when approaching MWI is reading too much into it. These Other Worlds "exist" in similar sense to the number i. MWI does _not_ claim anything about there being infinite alternative equivalent planes of existence where these physically manifest or anything like that.

You make an extraordinary claim.

Where in MWI do you believe the preferred unique macroscopic reality is defined?

Is many worlds falsifiable?

Exactly.

Any good scientific theory must create falsifiable hypotheses.

Otherwise it’s just a nice story.

>Any good scientific theory must create falsifiable hypotheses.

For any behavior inside the world, this is good.

But for the world itself and what harbor's it, asking for falsifiability is like measuring the expansion of space using a ruler that inhabits the same space.

Even science, that works in terms of cause and affect, which implies space and time, cannot be used to describe space and time itself.

Vanilla "scientists" have been trying to do that, but that is a dead end.

> But for the world itself and what harbor's it, asking for falsifiability is like measuring the expansion of space using a ruler that inhabits the same space.

Which exactly is what general relativity is centrally about and the reason why general relativity is defined in terms of intrinsic properties of the Einstein manifold describing the space of the universe. Intrinsic properties are, colloquially, indeed properties that can be measured "using a ruler that inhabits the same space".

Gauß' Theorema Egregium [1] is an early predecessor of intrinsic properties of general manifolds, and says that the curvature of a surface can indeed be "be determined entirely by measuring angles, distances and their rates of change on a surface, without reference to the particular manner in which the surface is embedded in the ambient 3-dimensional Euclidean space" ([1]).

[1] https://en.wikipedia.org/w/index.php?title=Theorema_Egregium...

Also why LIGO works but Michelson-Morley failed: you can use the ruler distortion as a signal, with some caveats.

In LIGO, we detect the far away distortions propagating through our rulers and the differential effect of those waves.

But Michelson-Morley failed because the ruler distorted synchronously with the signal we tried to measure — since we mistakenly believed EM and matter were different fields.

How are general-relativistic effects relevant for the outcome of the Michelson-Morley experiment?

> How are general-relativistic effects relevant for the outcome of the Michelson-Morley experiment?

General-relativistic effects are relevant for the outcome of the Michelson-Morley experiment in the sense that the general theory of relativity is a generalization of the special theory of relativity. :-)

Otherwise: the additional predictions that the general theory of relativity makes about gravity, curvature of space etc. are not relevant for the outcome of the Michelson-Morley experiment.

I mean, if you're claiming that general relativity is relevant here, then you need to show that quantitatively.

What do you mean?

You seem to think I’ve said something very technical, while I’ve merely pointed out a well-known effect of Lorentz invariance and interferometry: you can’t detect an “aether” signal coincident with the detector, because the detector is distorted synchronously.

Michelson-Morley was never going to work because it relied on the assumption matter wasn’t subject to aether wind — which turned out to be wrong, as matter is subject to relativistic effects and fields unify. You needed that independence to generate the differential the interferometry amplified.

By contrast, LIGO measures an effect far removed and not co-moving with the detector. So it works.

> measuring the expansion of space using a ruler that inhabits the same space

We do that, routinely: that’s how we do cosmology.

> We do that, routinely:

Yea, that is why we are not getting any where...

> Yea, that is why we are not getting any where...

Which alternative way of doing measurements do you propose? As far as I know, measuring intrinsic properties, i.e. "using a ruler that inhabits the same space" is with our current technology the only possible way of doing measurements.

Assuming that we are trying to understand the ground truth about existence by doing these measurements, may be we can acknowledge the limitation and stop trying to do it. Then we can be open minded and stop being hung up of the idea of "falsifiability", and could come up with or give more consideration to radically different hypothesis that we might come up with alternative measurements that we could make, that can prove or disprove them.

So time extending into the future is not a useful hypothesis? Space continuing beyond the cosmic horizon is not a useful hypothesis? The past entropy of the past being arbitrarily low (vs what is essentially last tuesdayism) is not a useful hypothesis?

Time extending into the future is validated by direct experience.

A continuum of variants of myself is bought.

What is the value of assuming that literally every possible trajectory actually happens, but somehow I am only in one of them, while also being a continuum of other ones? If everything is true, than nothing is true.

If time did not continue into the future, it would not be observable. Therefore hypothesis that it will continue to do so is not disprovable.

As far as multiverse goes, there isn't any inherit value in assuming that the wavefunction as given actually happens, it's just a simpler explanation than trying to come up with (arguable unprovable) ways to cull the wavefunction.

Yes. Many worlds is just the Schrödinger equation without the wave function collapse. It makes less assumptions. Falsify the Schrödinger equation, and you have falsified many worlds. However, is the wave function collapse falsifiable? It's one postulate which many worlds doesn't make, and it cannot be confirmed or falsified by experiment.

This is not what falsifiability means in the Popperian sense. You are confusing falsifiability of a theory’s predictions with falsifiability of an additional claim of what those theories mean. We might as well say that the simulation hypothesis is falsifiable because the laws of physics govern our simulated universe, so if you can falsify those laws you can falsify the simulation hypothesis. That being said, the concept of falsifiability is not without its weaknesses.

> Many worlds is just the Schrödinger equation without the wave function collapse.

It is not, it is the Schrödinger equation plus an extra rule that says that classical observers are only certain kinds of quantum states. There's no explanation in the MWI for why a device never reads out that a particle is 1/sqrt(2) |here> + 1/sqrt(2)|there>, even though that is exactly as probable a state as being |here>. And it turns out that this is exactly equivalent to positing wave function collapse / the Born rule.

And no, decoherence has nothing to do with this. Decoherence explains why there is no observable interference at the classical level between these states, not why you can only observe some states.

This is known as the preferred basis problem, for anyone who wants to read more about it.

Doesn’t the structure of the Hamiltonian (local interactions) set what the preferred basis are?

Well, when we set an experiment up, we can measure in any basis we like, and get the corresponding results as probabilities per the Born rule, so I don't think there are any constraints on this. Plus, local interactions can't explain why the same classical basis arises globally - after all, when we investigate a distant star, it's never detected as being in some other basis then the local area.

Yes, and all the postulates have been evidenced and panned out.

> Many worlds is just bare bones QM.. If any other theory is proposed, it should be falsifiable

Many worlds isn't falsifiable, either. There's no reason to accept one over the other.

You look at if the postulates are falsifiable. All the postulates from me have been evidenced or are falsifiable.

The Copenhagen wavefunction collapse is unfalsifiable.

The Copenhagen interpretation doesn't even deserve to sit with the other interpretations because it's not well defined. It's protoscience, like alchemy.

It's "rules of thumb for a working physicist".

"Many-worlds just states there is no such thing as wave function collapse" is the emotional statement. The contempt for many-worlds is both principled and rational.

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