I Physicists disagree wildly on what quantum mechanics says about real…

[DrChinese]

You’re probably thinking “duh”. But that’s actually the title of the article that was published yesterday.

Physicists disagree wildly on what quantum mechanics says about reality, Nature says​

If there was any confusion in your mind about the confusing nature of physicists’ viewpoints… this should affirm that.

Respondents (out of 1,101) that were “confident” in their preferred interpretation:

Copenhagen 6%
Epistimic/Information-based 4%
MWI 3%
Bohmian 3%

All others (retrocausal, superdeterminism, etc.) were 1% or less.

-DrC

 

[.Scott]

I just read the article.

First off, it's encouraging to know that so many Physicists can do anything "wildly".
... The next step for me is clear - reread it and respond to the questions.

Q1: My "favored explanation" of QM:
The 10 choices (excluding "other") are actually a mixture of theories, interpretations, and outlooks. Clearly, you can mix and match - and with a true quantum mind, you should be able to hold a superposition of almost any combination. ;)
The article continues with descriptions of numerous choices.
Here are my reactions:

* Multiworld - I dislike this because I see it as a distraction from the problem at hand. Are some worlds more likely than others? Is this time symmetric - if worlds continuously divide, do they also continuously rejoin? And there is an information problem: The set of all letters is less information that 26 sets each containing 1 letter - the location of any spot in the universe goes from something like x,y,z,t to x,y,z,<a whole history of path decisions>,t.

* Bohemian - I don't immediate dispose of this. It serves as a good example of the kind of thing you need to do to make the pieces (ie, experimental results) fit into what we always hope for in a Newtonian universe. Occam suggests picking the simplest explanation - but in this case, the simplest "explanation" is pretty klutzy.

* Epistemic - I view this as a kind of foggy, ill-defined side road of Physics. Here's what the article says: "Nature’s survey suggests that ‘epistemic’ descriptions, which say that quantum mechanics reveals only knowledge about the world, rather than representing its physical reality ...". There's definitely some ambiguity in that definition. Whether something "represents" something else is entirely context-dependent. Nothing "inherently" represents anything else. Or perhaps it is only claiming that the information is incomplete - which, of course, it generally is. But I do have a use for this side road. Over the years, I've described my views and arguments on consciousness - but at its core, I see it as a fundamental reality tightly bound to entanglement - but not in any way "represented" by information.

* Spontaneous collapse - Even though I'm not crazy about the "collapse" part, I still hold a fondness for these lines of thought. I favor the notion that particles, molecules, etc. hang onto their wavelike character until it gets whittled down to minimal states by interference and probabilities. And even then - never say collapse. In time, some odd state that started out as unlikely could persist as a lead contender.

* Copenhagen interpretation - Certainly, if you're an engineer, this is a very pragmatic view. It's useful, but really, this is the non-explanation explanation. It's good to hear that only 36% of the Physicists "favor" this - and only 12% of those are "confident".

... I think they would have put me down for "other".

I was going to do all the questions - but life interrupts me.

 

[phinds]

I thought it would be informative to post the full chart from the article:

 

[Swamp Thing]

In superdeterminism, it's already fixed what everyone is going to believe, right?

 

[PeroK]

In superdeterminism, it's already fixed what everyone is going to believe, right?

Not necessarily. SD only determines the necessary correlations to make it look like QM is right. There are no macroscopic correlations. If you and a colleague each pick a sequence, then the choices appear uncorrelated. If, however, you use your respective choices to determine angles in a Bell experiment, then your choices are correlated with the particles involved.

Straight SD, where everything is predetermined, isn't enough to make it look like QM is correct. SD has to work precisely to undermine QM!

 

[bob012345]

Any theory which causes more confusion than clarity after a century of use should probably be junked.

 

[phinds]

Any theory which causes more confusion than clarity after a century of use should probably be junked.

You have missed the point. The theory, that is the "shut up and calculate" math theory does NOT cause confusion and in fact is, as the article says, "one of the most successful theories in science". It's how we choose to INTERPRET, in English, the results, that differ.

 

[MrRobotoToo]

In superdeterminism, it's already fixed what everyone is going to believe, right?

That's right: a superdeterministic model would be completely deterministic in the classical sense. However, no one knows how to construct a deterministic, causally local hidden variable model that is able to generate the non-local correlations observed in Bell experiments without resorting to some kind of conspiratorial fine-tuning of the model's initial conditions.

 

[bob012345]

You have missed the point. The theory, that is the "shut up and calculate" math theory does NOT cause confusion and in fact is, as the article says, "one of the most successful theories in science". It's how we choose to INTERPRET, in English, the results, that differ.

All I can say in my defense is that when I took it, the math caused a lot of confusion!

 

[martinbn]

You have missed the point. The theory, that is the "shut up and calculate" math theory does NOT cause confusion and in fact is, as the article says, "one of the most successful theories in science". It's how we choose to INTERPRET, in English, the results, that differ.

It is not any better in other languages either.

 

[sbrothy]

I still like the Montevideo Interpretation, which I doubt is even taken seriously. There's just something that intuitively makes sense to me. (As clocks have to be more and more precise more energy is expended until they become black holes.)And yes, I know intuition is a very bad measure

 

[syed]

You have missed the point. The theory, that is the "shut up and calculate" math theory does NOT cause confusion and in fact is, as the article says, "one of the most successful theories in science". It's how we choose to INTERPRET, in English, the results, that differ.

the theory doesn't tell you to shut up and calculate though, that itself is an interpretation :) but otherwise, agreed

 

[phinds]

the theory doesn't tell you to shut up and calculate though, that itself is an interpretation :) but otherwise, agreed

No, that is not an interpretation, it is how you use math to describe reality. How you describe it in English is an interpretation.

 

[bhobba]

Actually, over the years, I have changed my view on QM interpretations. I still hold to the Ensemble interpretation. However, I no longer tend to worry about it. It comes as no surprise, since we only know the math and have no direct contact with the quantum realm, different views abound. I consider a much more important question is: knowing the math (which everyone agrees on), how does the world of common sense emerge? Advances in that area are not opinion, but follow from QM, see
https://www.sciencenews.org/blog/context/gell-mann-hartle-spin-quantum-narrative-about-reality.

I have a mathematical modelling hand-wavy type argument for the foundations of QM, built around Gleason's important theorem. It serves a psychological crux, making it seem less weird. But at rock bottom, I don't know what it is, just a reasonable argument for its mathematical structure. I think too many (including me in the past) get caught up in what has progressed historically at a snail's pace, e.g., things like Bell's Theorem, etc, but with no end in sight. Also, it must be mentioned we know ordinary QM is wrong (it can't account for particle creation and destruction), for that you need Quantum Field Theory (QFT). Wienberg has what he refers to as a folk theorem. At large enough distances, any theory will look like a QFT. We may be stuck with what are called Effective Field Theories (EFTs) that, from the start, recognise this.

We sometimes hear that QM and GR are incompatible. EFT has modified that view:
https://websites.umass.edu/donoghue/research/quantum-gravity-and-effective-field-theory/

Maybe it is too gloomy a picture, but it must be remembered that every theory has assumptions, every single one. It could be different in QM in that the assumption is that all paths lead to Rome, but we don't know where we came from. Astrophysics and cosmology may shed some light on this; only time will tell.

Thanks
Bill

 

[syed]

No, that is not an interpretation, it is how you use math to describe reality. How you describe it in English is an interpretation.

"shut up and calculate" is often related to the Copenhagen interpretation. The term comes from David Mermin and he coined it to literally summarize Copenhagen-type views:

https://hsm.stackexchange.com/questions/3615/who-was-the-first-to-say-shut-up-and-calculate
https://en.wikipedia.org/wiki/Copenhagen_interpretation

 

[PeroK]

In my opinion, soundbites like "shut up and calculate" or "spooky action at a distance" are ultimately meaningless. They represent the negation of thought. Rational analysis is replaced by a single clever phrase that undermines an idea or even settles the debate.

The question, put in more sober terms, is whether mathematics is sufficient to describe nature at a fundamental level. Several centuries ago, mathematics itself was held back by the idea that things must be "real" or "pure"; or, that mathematics had to represent God's will in some way. Complex numbers were not immediately embraced because mathematicians didn't accept that mathematics might go beyond human intuition.

In the 20th century, Godel's theorem destroyed the illusion of the perfection of mathematics - mathematicians knew enough by this stage to accept it. Or, they were forced to accept it, because it had been proved!

The question is whether physicists (and philosophers) have to accept a similar conclusion for fundamental physics. It can probably never be proven, in the way that Godel proved that mathematics must be incomplete, so there will always be people who do not accept mathematics itself as the fundamental description of nature.

It's all very well to criticise physicists for the failure to agree on a single interpretation of QM. But, if it's impossible (like proving Euclid's 5th postulate and establishing the one true geometry), then all the interpretational arguments are a waste of time.

PS note that developing different interpretations is not a waste of time, as they can give key insights into what the mathematics is telling us.

 

[martinbn]

I am not sure how useful these surveys are. There isn't enough clarification about the meaing of terms in the questions and answers. So everyone has to interpret them in some way. Do they all interpret them the same way! I am not sure. It is very possible that people who hold the same view gave different answers and people who hold differetnt views gave the same answer to a given question. I have seen mathematicians discusing platonism or formalism or some other -isms, and disagreeing untill they explained to each other what they meant by those -isms.

 

[bhobba]

The question, put in more sober terms, is whether mathematics is sufficient to describe nature at a fundamental level.

All experience says it is.

What Wigner said still holds:
https://webhomes.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf

In my opinion, that is the 'real' mystery - not quantum mechanics.

Thanks
Bill

 

[physika]

That's right: a superdeterministic model would be completely deterministic However, no one knows how to construct a deterministic, causally local hidden variable model that is able to generate the non-local correlations observed in Bell experiments without resorting to some kind of conspiratorial fine-tuning of the model's initial conditions.

A block universe theory/model


....

 

[iste]

In my opinion, that is the 'real' mystery - not quantum mechanics.

I don't find that a mystery at all to be honest; to me, its like asking about the unreasonable effectiveness of language in describing things, which I think can be easily deflated.

 

[MrRobotoToo]

A block universe theory/model


....

If you were to make it relativistic, then arguably yes!

 

[gentzen]

I don't find that a mystery at all to be honest; to me, its like asking about the unreasonable effectiveness of language in describing things, which I think can be easily deflated.

Not sure what you mean: It could be:

• If current language(s) would not be good enough for the job, we would keep inventing new language concepts until it starts working. Which gets even more obvious with math, because the math that can describe quantum mechanics is completely different from the math available to the ancient greeks.
• Mathematics is just a sort of language, and obviously language is able to desribed anything, in principle.
• ...

 

[PAllen]

I still like the Montevideo Interpretation, which I doubt is even taken seriously. There's just something that intuitively makes sense to me. (As clocks have to be more and more precise more energy is expended until they become black holes.)And yes, I know intuition is a very bad measure

I’d never seen that one. At first glance, I like it. Now, I have dig in to determine whether I can believe it …

 

[sbrothy]

It's generally not taken very seriously. It may even have been refuted(?). Still, I like it's "arguments" on an intuitive level, which - as I know - is a bad measure for determining what is right and wrong. Like saying this or other theory is "correct" because it's "beautiful".

EDIT: Also, it doesn't even make any difference to the actual outcomes, but I guess that interpretations for you.

I think this one: The Montevideo Interpretation of Quantum Mechanics: a short review, is a better start.

 

[.Scott]

@bhobba responding to @PeroK 's:
"The question, put in more sober terms, is whether mathematics is sufficient to describe nature at a fundamental level. "

All experience says it is.

What Wigner said still holds:
https://webhomes.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf

In my opinion, that is the 'real' mystery - not quantum mechanics.

Thanks
Bill

So, @PeroK says "fundamental level", and @bhobba then describes it as a "real mystery".
In both cases, they seem to be imagining some kind of Physics "end game". And then, perhaps with @PeroK but certainly with @bhobba, it is an end game where nothing is left on the table.

Perhaps I have no patience for "mystery", but I see things differently - or perhaps only more explicitly.

There are the rules of Physics which we are working to uncover - a task that may well outlast our species.
We use Math to assimilate and model our observations. I have no doubt that Math is up to the task. After all, all we are trying to do is model the observed results of the mechanics and it's hard to imagine a situation where we fail to come up with a working model because of limitations in Math rather than limitations in Mathematicians.

But then there is this "reality" thing:

First, let me show you what I see as the connection between "consciousness" and "reality". And by "consciousness", I am referring to a very basic Physical element - not necessarily to a "human consciousness" with all of its brain-based "animal", "self", "social", etc attachments.
In my view, reality and this basic kind of consciousness are very tightly bound. A universe without any form of consciousness is just an uninstantiated version of Physics. And if the rules of that universe have never been contemplated in a "conscious" world such as ours, it isn't even a dream - it is nothing.

So, I view "consciousness" as a kind of substrate to a universe.
For the case-in-point, (ie, our universe), I have posted on this before. Based on my observation of my own consciousness and discussions with others on the nature of theirs, human consciousness has the capacity to hold well more than a few bits of information in a single state. Given the known Physics, this is entanglement.

And that makes QM entanglement as a tie-point between the observable mechanics of our universe and its conscious substrate.

That tie-point is my boundary of Physics. That substrate is consciousness and I see absolutely no potential to uncovering any further information about it. We can still create further models of entanglement - and perhaps refine the exact role of the tie point(s), but there is no observation that would discern the differences between "reality" and "nothing" beyond what is immediately apparent.

So, when I use the term "fundamental" in Physics, I am only referring to the mechanics down to the tie-points and no further - because I see no reason to expect that the reality substrate itself is "explainable" or even by its nature could be explainable.

 

[Fra]

What Wigner said still holds:
https://webhomes.maths.ed.ac.uk/~v1ranick/papers/wigner.pdf

In my opinion, that is the 'real' mystery - not quantum mechanics.

In the perspective of evolution of law, an answer was proposed here by Smolin

"The view I will propose answers Wigner’s query about the ”unreasonable effectiveness of mathematics in physics” by showing that the role of mathematics within physics is reasonable, because it is limited. In particular, there is no mathematical object which is isomorphic to the universe as a whole, and
hence no perfect correspondence between nature and mathematics."
-- https://arxiv.org/abs/1506.03733

I see this is related to that every particular mathematical model typically describes an "effective theory", meaning it is limited to a particular domain. It's effectiveness is not a coincidence.

/Fredrik

 

[sbrothy]

@bhobba responding to @PeroK 's:
"The question, put in more sober terms, is whether mathematics is sufficient to describe nature at a fundamental level. "



So, @PeroK says "fundamental level", and @bhobba then describes it as a "real mystery".
In both cases, they seem to be imagining some kind of Physics "end game". And then, perhaps with @PeroK but certainly with @bhobba, it is an end game where nothing is left on the table.

Perhaps I have no patience for "mystery", but I see things differently - or perhaps only more explicitly.

There are the rules of Physics which we are working to uncover - a task that may well outlast our species.
We use Math to assimilate and model our observations. I have no doubt that Math is up to the task. After all, all we are trying to do is model the observed results of the mechanics and it's hard to imagine a situation where we fail to come up with a working model because of limitations in Math rather than limitations in Mathematicians.

But then there is this "reality" thing:

First, let me show you what I see as the connection between "consciousness" and "reality". And by "consciousness", I am referring to a very basic Physical element - not necessarily to a "human consciousness" with all of its brain-based "animal", "self", "social", etc attachments.
In my view, reality and this basic kind of consciousness are very tightly bound. A universe without any form of consciousness is just an uninstantiated version of Physics. And if the rules of that universe have never been contemplated in a "conscious" world such as ours, it isn't even a dream - it is nothing.

So, I view "consciousness" as a kind of substrate to a universe.
For the case-in-point, (ie, our universe), I have posted on this before. Based on my observation of my own consciousness and discussions with others on the nature of theirs, human consciousness has the capacity to hold well more than a few bits of information in a single state. Given the known Physics, this is entanglement.

And that makes QM entanglement as a tie-point between the observable mechanics of our universe and its conscious substrate.

That tie-point is my boundary of Physics. That substrate is consciousness and I see absolutely no potential to uncovering any further information about it. We can still create further models of entanglement - and perhaps refine the exact role of the tie point(s), but there is no observation that would discern the differences between "reality" and "nothing" beyond what is immediately apparent.

So, when I use the term "fundamental" in Physics, I am only referring to the mechanics down to the tie-points and no further - because I see no reason to expect that the reality substrate itself is "explainable" or even by its nature could be explainable.

Math has been very successful in describing our world and letting us manipulate it. I expect that to continue even though we seem to be at an impasse. I'm not sure math or even quantum mechanical interpretations have anything to say about consciousness per se. I think that's a completely different problem. An important one mind, but not a study I'd expect clear answers from in the near, or even remote, future.

But perhaps, just perhaps, philosophy based on actual science could offer some hints as to the nature of existence. Ontology is it?

 

[sbrothy]

"shut up and calculate" is often related to the Copenhagen interpretation. The term comes from David Mermin and he coined it to literally summarize Copenhagen-type views:

https://hsm.stackexchange.com/questions/3615/who-was-the-first-to-say-shut-up-and-calculate
https://en.wikipedia.org/wiki/Copenhagen_interpretation

This is a little disappointing from where I stand. First I find out that H. C. Ørsted isn't all he's hyped up to be, and now it's Niels Bohr's turn? (I realize that's not the only thing he's known for though.)

 

[gentzen]

This is a little disappointing from where I stand. First I find out that H. C. Ørsted isn't all he's hyped up to be, and now it's Niels Bohr's turn? (I realize that's not the only thing he's known for though.)

Thanks, your comment made me notice that the wikipedia article "implicitly proposes" a solution to the whole conundrum surrounding the Copenhagen interpretation:

In a 1960 review of Heisenberg's book, Bohr's close collaborator Léon Rosenfeld called the term an "ambiguous expression" and suggested it be discarded.[22] However, this did not come to pass, and the term entered widespread use.[16][19] Bohr's ideas in particular are distinct despite the use of his Copenhagen home in the name of the interpretation. [23]

Instead of trying to fit Bohr's ideas into the Copenhagen interpretation, or distinguishing between Heisenberg's and Bohr's variant of the Copenhagen interpretation, simply take the ideas of Heisenberg and his pupils as the Copenhagen interpretation, and let Bohr's ideas find a better home.

The survey didn't do this. If you adhere to the ideas of Niels Bohr or Asher Peres, your only reasonable choices were "Copenhagen Interpretation" or "Other - non-categorized".

 

[sbrothy]

Thanks, your comment made me notice that the wikipedia article "implicitly proposes" a solution to the whole conundrum surrounding the Copenhagen interpretation:

Instead of trying to fit Bohr's ideas into the Copenhagen interpretation, or distinguishing between Heisenberg's and Bohr's variant of the Copenhagen interpretation, simply take the ideas of Heisenberg and his pupils as the Copenhagen interpretation, and let Bohr's ideas find a better home.

The survey didn't do this. If you adhere to the ideas of Niels Bohr or Asher Peres, your only reasonable choices were "Copenhagen Interpretation" or "Other - non-categorized".

Well, I’m glad to be of help. However little or indirect it may be.

 

[Ben vdP]

It seems to me that the root of the problem or issue is that it is tried too much to
see quantum particles as semi-classical objects or as particles\waves.
The message would then be to abandon those ideas or see those as approximations or illusions.
It is more modern to view a quantum particle as a field.

Is there an interpretation that is based on quantum particles as being fields?

Assumptions that are made at the measurement level can make perfect sense and be fruitful or even vital for all kinds of calculations. And yet, at the quantum level they can turn out to be false.

For example, if you assume that a quantum particle qp must be at a certain spot or occupies an amount of space with a certain shape and size, then already you have made a false assumption.

There is no necessity for a qp to have a certain size or shape. If you would be able to shrink to the size of a proton then there will be nothing there that you would be able to hold in your hand. There does not exist any tangible substance. A wall looks massive or solid but on a smaller scale it turns out to be an illusion.

What there is, is getting described as a field. A field has no shape and size. A galaxy hasn't either.
In the large it appears to have some disk shape. But when looking closer at it there are no sharp boundaries.
The solar system doesn't either. Here you have a tug of war between the radiation and fields of the sun versus interstellar space. But what defines the shape and size of the solar system, it's fuzzy.

A field inherently has a non-local aspect, so does a force that works at a distance. I think Bohm captured this the most but I do not expect Bohm to be right. If there is an issue with propagation faster then the speed of light, well, energy cannot go faster. But if there is no energy involved like with classical group waves then there might be a door open.

So, are there existing interpretations that does more justice to the field concept?

A bit silly, but try, for a change, to view a qp as a disturbance in space, an excitation, a resonance, an agglomerate of (group) waves, a peace of spacetime that has gotten itself into a knot, a cluster of adjacent virtual particle pairs constantly getting created and destroyed, a node in a large dynamic network showing collective behaviour , a fluidium, the exact nature is tbd.

 

[bhobba]

A field inherently has a non-local aspect, so does a force that works at a distance.

You need to become acquainted with Wigner's No-Interaction Theorem.

It explains both why fields must exist and why they most definitely are local.

The correct setting to discuss all this stuff is QFT, and it is a fruitful area of active research - but difficult and complex with several open questions:

https://arxiv.org/abs/2410.19101

Intuitively, in QFT, when particles are entangled, they become a single 'double knot' in the field. When observed, it is like cutting the knot. Think of a rubber band that is stretched further and further. When cut, it becomes two pieces of rubber. Was locality violated? I don't mean Bell Locality - we know it surely is - but the everyday common sense locality that SR is built on.

IMHO, the root of the endless discussions of Bell and its implications is tied up with not distinguishing Bell locality from our usual conceptions of locality. Bell locality (or IMHO a much better name - factorizability) is the condition that any correlations between distant events be explicable in local terms. Note that it concerns correlations—a statistical concept—not locality in SR.

Thanks
Bill

 

[elias001]

I am a fan of the "shut up and calculate" approach. I mean i expect it of engineers when they have to make use of it.

 

[weirdoguy]

Is there an interpretation that is based on quantum particles as being fields?

That is why I think that all those "foundations of quantum mechanics" and interpretational stuff are total waste of time at the moment. We know that QFT is in a sense more fundamental than non-relativistic QM. And we know it works differently. So even if one finds intepretation that most physicists would be ok with, what is the chance that it would survive going into full relativistic mode?

 

[bob012345]

I’d like to see an AI trained only on the accumulated experimental data and ask it to come up with a logical and consistent theory of nature from scratch.

 

[PeroK]

I’d like to see an AI trained only on the accumulated experimental data and ask it to come up with a logical and consistent theory of nature from scratch.

It will be fascinating to see what AI eventually comes up with. My guess is that we won't understand what it's doing, or how it comprehends the universe. In fact, my guess is it will be free of the philosophical hang-ups that bedevil human thinking.

 

[gentzen]

That is why I think that all those "foundations of quantum mechanics" and interpretational stuff are total waste of time at the moment. We know that QFT is in a sense more fundamental than non-relativistic QM.

So your guess is that there is no interpretation of non-relativistic QM that is comparable to Einstein's solution of the riddles of Maxwell's equations, namely that simultaneity is relative to the state of motion of the observer.

And we know it works differently. So even if one finds intepretation that most physicists would be ok with, what is the chance that it would survive going into full relativistic mode?

On the other hand, you guess that the interpretational riddles do have a "nice solution" for QFT. Who knows, maybe you are right. But Heisenberg&co believed that interpreting QFT (especially nuclear/particle physics) would be even more challenging than interpreting QM. Especially, there won't be a return to classical concepts, only to concepts even less intuitive than those required for understanding QM.

 

[ohwilleke]

You have missed the point. The theory, that is the "shut up and calculate" math theory does NOT cause confusion and in fact is, as the article says, "one of the most successful theories in science". It's how we choose to INTERPRET, in English, the results, that differ.

Shut up and calculate, of course, isn't truly just a math theory. In real life, scientists have to deal with what we called "story problems" in grade school, not bare equations and numbers.

To do quantum physics, one still has to make the part of the math that relates to real world observables correspond to things in the real world, and everyone who uses quantum physics still has to be able to operationally define concepts like what a "measurement" that collapses the wave function is, in a consistent and correct manner. In other words, even the "shut up and calculate" folks still have to interpret the math.

And, while there are lots of safe harbor circumstances in which the way that the math corresponds to real life observables is clear, there are indeed circumstances, like the precise definition of a "measurement", where there are gray area circumstances in which a scientist doing quantum mechanics won't be sure about how to apply the math to real world experiments in advance and the scientists just have to do the experiments to find out. This isn't a huge area of research, but there is definitely a subset of physicists who are working on those questions.

What the various "interpretations of quantum mechanics" are interpreting is not really the results. Instead, it is a non-mathematical description of the mechanism that gives rise to the observable results.

"Shut up and calculate" is a slogan for being deliberately incurious and agnostic about the physical reality of, and mechanism associated with, the part of the math in quantum physics calculations that does not correspond to real life observables.

Part of the reason that we feel that we need such interpretations is that we and all of our ancestors and ancestor species for as far back as animals have had brains (with the exception of small numbers of scientists in the last century and a half), have lived in circumstances where classical physics explains everything that they encounter and have to interact with in their entire lives, and any more complex quantum understanding of the world, even though it was more accurate, would have been selective fitness reducing because it would have taken more brain power without producing any different results.

In other words, we are hard wired to conceptualize the world that we encounter in a classical physics kind of way. But, in circumstances where quantum physics predicts things that are different from what classical physics predicts, our hard wiring gives us strong intuitions that are simply wrong. Learning that this intuition is wrong is rather distressing at first. It is the kind of thing that people earnestly trying to understand the world in the context of a comprehensive world view about the physical world can lose sleep over.

Understanding quantum physics requires us to abandon this hard wired intuition, reinforced by almost all of an entire lifetime of experience, in favor of a different, more accurate understanding of how the world works, arising from formal instruction and from experimental observation of the way that the world works in the highly specialized circumstances in which quantum physics makes different predictions about what we will observe than classical physics does.

This isn't to say that there couldn't be some interpretation that is heuristically more natural feeling than "shut up and calculate", which makes it easier to have the correct intuition about what quantum physics predicts in a particular situation accurately without actually doing all of the calculations. But none of the prevailing "interpretations of quantum physics" do this in a particularly satisfactory way that sets it apart from the alternatives as the clearly superior choice. There are interpretations out there that are clearly wrong or unhelpful, but as the survey at the start of the thread demonstrates, there are several alternatives that aren't manifestly incorrect in the eyes of well-informed scientists. And, there is no decisive consensus favorite.

 

[bob012345]

I think of shut up and calculate as more of an inside joke among physicists rather than some dogmatic statement. It mades a point with humor.

 

[ohwilleke]

I think of shut up and calculate as more of an inside joke among physicists rather than some dogmatic statement. It mades a point with humor.

You aren't wrong. But the point that is being made can be easily misunderstood if you aren't living it on a daily basis.

Since the word "interpretation" is slippery, it is useful to be specific and concrete about what it means in this context by demonstrating that "shut up and calculate" isn't literally true in the way that many people misunderstand it to be. This is useful because this narrows and clarifies what is really at issue when we talk about interpretations of quantum physics. The hope is that this clarity, in turn, will produce more enlightened thinking about the subject.

 

[syed]

Shut up and calculate, of course, isn't truly just a math theory. In real life, scientists have to deal with what we called "story problems" in grade school, not bare equations and numbers.

To do quantum physics, one still has to make the part of the math that relates to real world observables correspond to things in the real world, and everyone who uses quantum physics still has to be able to operationally define concepts like what a "measurement" that collapses the wave function is, in a consistent and correct manner. In other words, even the "shut up and calculate" folks still have to interpret the math.

And, while there are lots of safe harbor circumstances in which the way that the math corresponds to real life observables is clear, there are indeed circumstances, like the precise definition of a "measurement", where there are gray area circumstances in which a scientist doing quantum mechanics won't be sure about how to apply the math to real world experiments in advance and the scientists just have to do the experiments to find out. This isn't a huge area of research, but there is definitely a subset of physicists who are working on those questions.

What the various "interpretations of quantum mechanics" are interpreting is not really the results. Instead, it is a non-mathematical description of the mechanism that gives rise to the observable results.

"Shut up and calculate" is a slogan for being deliberately incurious and agnostic about the physical reality of, and mechanism associated with, the part of the math in quantum physics calculations that does not correspond to real life observables.

Part of the reason that we feel that we need such interpretations is that we and all of our ancestors and ancestor species for as far back as animals have had brains (with the exception of small numbers of scientists in the last century and a half), have lived in circumstances where classical physics explains everything that they encounter and have to interact with in their entire lives, and any more complex quantum understanding of the world, even though it was more accurate, would have been selective fitness reducing because it would have taken more brain power without producing any different results.

In other words, we are hard wired to conceptualize the world that we encounter in a classical physics kind of way. But, in circumstances where quantum physics predicts things that are different from what classical physics predicts, our hard wiring gives us strong intuitions that are simply wrong. Learning that this intuition is wrong is rather distressing at first. It is the kind of thing that people earnestly trying to understand the world in the context of a comprehensive world view about the physical world can lose sleep over.

Understanding quantum physics requires us to abandon this hard wired intuition, reinforced by almost all of an entire lifetime of experience, in favor of a different, more accurate understanding of how the world works, arising from formal instruction and from experimental observation of the way that the world works in the highly specialized circumstances in which quantum physics makes different predictions about what we will observe than classical physics does.

This isn't to say that there couldn't be some interpretation that is heuristically more natural feeling than "shut up and calculate", which makes it easier to have the correct intuition about what quantum physics predicts in a particular situation accurately without actually doing all of the calculations. But none of the prevailing "interpretations of quantum physics" do this in a particularly satisfactory way that sets it apart from the alternatives as the clearly superior choice. There are interpretations out there that are clearly wrong or unhelpful, but as the survey at the start of the thread demonstrates, there are several alternatives that aren't manifestly incorrect in the eyes of well-informed scientists. And, there is no decisive consensus favorite.

This is not an accurate way of viewing things. It is not that we have a true quantum explanation of the world that is complete and that our intuitions are wrong. It is rather that we simply don't know what is going on. For you to say that our intuitions are wrong implies that there is no clear, coherent picture of reality under the equations in current quantum mechanics. But there is no evidence behind this claim, and that would immediately rule out any interpretation that does claim to say there is more going on under the hood, like the many worlds interpretation or bohmian mechanics or whatever else may arise.

Equations alone never explain everything: they just restate patterns we observe. Schrödinger’s equation, for instance, tells us how the wavefunction evolves, but it does not tell us how and why we get particular measurement outcomes rather than others. This is true across physics: Newton’s laws didn’t explain what gravity “is,” they described the fact that masses influence each other, not how. Many were baffled as to how masses separated far apart from each other could affect each other at a distance. This is a classic case of a conflict with intuition. And their intuitions ended up being right: there was no action at a distance. Relativity and quantum field theory, for all their mathematical power, still need an ontological picture to make sense of what the math is describing: whether it’s curved spacetime, fields, or particles.

Historically, progress has come not just from better equations but from finding concepts that make those equations intelligible. Thermodynamics made sense once we understood molecules; relativity became intuitive once we saw spacetime as a geometric entity. So, to say that our classical intuitions are “wrong” in quantum physics misses the point. Our intuitions reflect the best ontological pictures we’ve had so far, shaped by the classical world. Quantum mechanics hasn’t provided a comparable picture yet. Without that, calling our intuitions wrong is premature.

 

[Herman Trivilino]

Any theory which causes more confusion than clarity after a century of use should probably be junked.

You'd be junking the most successful theory ever constructed. What would you have the tens of thousands of scientists, engineers, and technicians who use it every day to make contributions to society do? And do you propose we junk all the devices whose inventors made use of it? Or keep them but put a stop to the development of any new ones? And have the metrologists discard all the precision it has provided?

 

[ohwilleke]

This is not an accurate way of viewing things. It is not that we have a true quantum explanation of the world that is complete and that our intuitions are wrong.

Our intuitions are absolutely wrong, because our hard wired intuitions are based upon classical physics and classical physics are inconsistent with quantum physics.

It is rather that we simply don't know what is going on. For you to say that our intuitions are wrong implies that there is no clear, coherent picture of reality under the equations in current quantum mechanics.

It doesn't imply that. It implies that the true nature of, for example, electromagnetism is QED and not Maxwell's equations.

The reality of the equations is inconsistent with our classical physics intuition.

But there is no evidence behind this claim, and that would immediately rule out any interpretation that does claim to say there is more going on under the hood, like the many worlds interpretation or bohmian mechanics or whatever else may arise.

You are misstating the claim. There may or may not be a coherent picture of reality "under the hood" so to speak. "Reality" itself is arguably an inherently classical physics concept, although defining it is challenging.

Equations alone never explain everything: they just restate patterns we observe. Schrödinger’s equation, for instance, tells us how the wavefunction evolves, but it does not tell us how and why we get particular measurement outcomes rather than others. This is true across physics: Newton’s laws didn’t explain what gravity “is,” they described the fact that masses influence each other, not how. Many were baffled as to how masses separated far apart from each other could affect each other at a distance. This is a classic case of a conflict with intuition. And their intuitions ended up being right: there was no action at a distance. Relativity and quantum field theory, for all their mathematical power, still need an ontological picture to make sense of what the math is describing: whether it’s curved spacetime, fields, or particles.

Why does there have to be an ontological picture?

You "need" a way to operationalization how to turn equation results into observables. But, an ontological picture is a "want" not a "need". It is an unnecessary luxury that would be nice if we could get it.

Historically, progress has come not just from better equations but from finding concepts that make those equations intelligible.

Maybe we've hit the end of that history.

Thermodynamics made sense once we understood molecules; relativity became intuitive once we saw spacetime as a geometric entity.

Thermodynamics makes sense because deep down, it is just classical physics.

Relativity is, and always will be, contrary to our hard wired physical intuition. Even the leading researchers in the field struggle to really understand it outside some idealized special cases. One can overcome the drag down provided by intuition with grit, experience doing calculations with GR, and by rigorously overcoming one's natural intuitions, but it will always be a second language.

So, to say that our classical intuitions are “wrong” in quantum physics misses the point. Our intuitions reflect the best ontological pictures we’ve had so far, shaped by the classical world. Quantum mechanics hasn’t provided a comparable picture yet. Without that, calling our intuitions wrong is premature.

Our intuitions are wrong, without a doubt. There are half a dozen ways, at least, that quantum mechanics is flabbergastingly defiant of our lived experience and our wiring.

Whether our brains are even capable of intuitively groking quantum mechanics, as opposed to merely knowing how to use the equations that have been worked out, remains to be seen. Maybe we can, maybe we can't.

Nature has no obligation to work in a way that some evolved apes on a planet in an insignificant solar system at the fringe of a pretty ordinary galaxy in a vast universe are capable of understanding.

You can't teach a worm to understand English no matter how hard you (and the worm) try. There are many animals that are fundamentally incapable of understanding what their picture in a mirror is. We will never be able to truly appreciate the colors that butterflies can see, or what it feels like to have the sense of smell that a tracking dog does.

It could be that the ontological picture that is necessary to deeply and truly understand quantum mechanics is more than the 2025 model of Homo sapiens brain can process.

It could be that our brains our running on the metaphorical equivalent of Windows XP with a 256 KB memory card, and the "ontological picture of quantum mechanics" program requires Windows 11 and a 4 MB memory card to run. So, we may never be able to do this unless we can find a way to upgrade our brains, either through genetic engineering, or cyborg style part-machine enhancements. Indeed, we already rely on computers to grasp it and calculate it as it is.

If we're lucky, we can find some clever way to fit that kind of understanding with a very efficient "program" (i.e. interpretation of quantum mechanics) that can be understood by particularly intelligent people with the right mental bent. But, there is no guarantee that this is possible.

 

[bhobba]

So your guess is that there is no interpretation of non-relativistic QM that is comparable to Einstein's solution of the riddles of Maxwell's equations, namely that simultaneity is relative to the state of motion of the observer.

It is simply that we know standard QM is wrong, eg it predicts the hydrogen states are stationary, so can't jump between them. Yet they do. Interpreting it may be fun and help with interpreting the correct theory (which, as far as we can tell these days, is QFT that explains why the hydrogen states are not stationary), but is ultimately a dead end.

The modern situation is referred to as Effective Field Theory. This is based on what Wienberg refers to as a folk theorem. This states that any theory at sufficiently large distances will appear to be a QFT. The idea then is to accept our theories as approximations. One must then ask why try to interpret approximations? We know it is the only approximation from Wienberg's Folk Theorem - so there is no other choice. That there is no other choice is in itself an interpretation.

Also, surprisingly, usual QT is not a limiting case of QFT:
https://arxiv.org/abs/1712.06605

One must then ask, other than as mentioned, as an interesting exercise, the value of ordinary QM interpretations.

Thanks
Bill

 

[syed]

Our intuitions are absolutely wrong, because our hard wired intuitions are based upon classical physics and classical physics are inconsistent with quantum physics.

It doesn't imply that. It implies that the true nature of, for example, electromagnetism is QED and not Maxwell's equations.

The reality of the equations is inconsistent with our classical physics intuition.

You are misstating the claim. There may or may not be a coherent picture of reality "under the hood" so to speak. "Reality" itself is arguably an inherently classical physics concept, although defining it is challenging.

Why does there have to be an ontological picture?

You "need" a way to operationalization how to turn equation results into observables. But, an ontological picture is a "want" not a "need". It is an unnecessary luxury that would be nice if we could get it.

Maybe we've hit the end of that history.

Thermodynamics makes sense because deep down, it is just classical physics.

Relativity is, and always will be, contrary to our hard wired physical intuition. Even the leading researchers in the field struggle to really understand it outside some idealized special cases. One can overcome the drag down provided by intuition with grit, experience doing calculations with GR, and by rigorously overcoming one's natural intuitions, but it will always be a second language.

Our intuitions are wrong, without a doubt. There are half a dozen ways, at least, that quantum mechanics is flabbergastingly defiant of our lived experience and our wiring.

Whether our brains are even capable of intuitively groking quantum mechanics, as opposed to merely knowing how to use the equations that have been worked out, remains to be seen. Maybe we can, maybe we can't.

Nature has no obligation to work in a way that some evolved apes on a planet in an insignificant solar system at the fringe of a pretty ordinary galaxy in a vast universe are capable of understanding.

You can't teach a worm to understand English no matter how hard you (and the worm) try. There are many animals that are fundamentally incapable of understanding what their picture in a mirror is. We will never be able to truly appreciate the colors that butterflies can see, or what it feels like to have the sense of smell that a tracking dog does.

Again, this just isn't describing the issue correctly and is a common misunderstanding. You literally cannot even test QM's truth without some sort of intuitions that inevitably relate to classical physics. As just one quick example, when physicists say that they've measured the momentum of a particle, they never measure the momentum of a particle directly. They're basically measuring the time of flight and then use classical mechanics, not quantum mechanics, to calculate a momentum. The amount that people use classical physics unknowingly when trying to explain anything in quantum physics is phenomenal.

To this day, all tests of QM rely upon the concept of a measurement, and those measurement outcomes are locally and classically defined. As John Bell said, "The word ‘measurement’ should be banned altogether in quantum mechanics. It has no place except perhaps in discussions of experimental practice." See this link for a more detailed discussion on this.

In regards to the worm analogy, it is true that they are incapable of understanding certain things that we can, but this is not because their intuitions are different. It is because the very notion of understanding, especially conscious understanding, requires a certain type of brain that only we and possibly very few other animals have. So it is not that the worms have a different understanding. They have little to no conscious understanding of anything at all.

Last but not least, you cannot escape intuitions. You are using intuitions that you think are reasonable to even make your case that QM defies our historical intuitions, which again, given the current state of understanding of QM, is a very premature conclusion

 

[PeroK]

Last but not least, you cannot escape intuitions.

You have to if you study mathematics or modern physics. Although your main target is QM, the general theory of relativity entails curved spacetime. Not just curved space, but curved time. That is not intuitive. It also rests on the Lagrangian principle of maximal proper time, as the equivalent of Newton's second law, in order to describe timelike geodescics as the natural paths through spacetime for massive objects. Meanwhile, light travels along null geodesics, paths of zero spacetime distance. None of this is intuitive.

In fact, one could argue that Newton's law of gravity is unintuitive. This is what Newton had to say about his own theory:

“It is inconceivable, that inanimate brute matter should, without the mediation of something else, which is not material, operate upon and affect other matter without mutual contact…That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance, through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking, can ever fall into it. Gravity must be caused by an agent, acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers.”

— Sir Isaac Newton (Third letter to Bentley, 25 Feb 1693. Quoted in The Works of Richard Bentley, D. D. (1838), Vol. 3, 212-3.)

"Intuition", by definition, is a subjective collection of ideas that you have developed from ad hoc experiences as a human, living on planet Earth. That is not something that, in my opinion, can seriously be taken as the basis on which to reject all modern physics.

 

[Fra]

It is simply that we know standard QM is wrong, eg it predicts the hydrogen states are stationary, so can't jump between them. Yet they do. Interpreting it may be fun and help with interpreting the correct theory (which, as far as we can tell these days, is QFT that explains why the hydrogen states are not stationary), but is ultimately a dead end.

The modern situation is referred to as Effective Field Theory. This is based on what Wienberg refers to as a folk theorem. This states that any theory at sufficiently large distances will appear to be a QFT. The idea then is to accept our theories as approximations. One must then ask why try to interpret approximations? We know it is the only approximation from Wienberg's Folk Theorem - so there is no other choice. That there is no other choice is in itself an interpretation.

Also, surprisingly, usual QT is not a limiting case of QFT:
https://arxiv.org/abs/1712.06605

One must then ask, other than as mentioned, as an interesting exercise, the value of ordinary QM interpretations.

Thanks
Bill

I can't speak for others, but when I worry about "foundations of QM" it does not refers to non relativistic models of the atom, it refers to the foundations and constructing principles such as non commutative information and the measurement problem etc. All these issues are still in qft.

I rather see QFT (ie poincare invariant theory of measurements) as a special case of the applying some general yet unknown onstructing principles. As I think alot suggests at least to me that spacetime must somehow be emergent, it is a big mistake to think that qft in 4d space is a good startiing point.

I would expect that qft would follow as effective descriptions from a generalized qm principles along with spacetime in certain limits involving relationa betwwen system and context.

Its these deeper principles i seek when talking about qm foundations as they transcend 4d spacetime.

Yes QFT is a better bigger theory than nrqm but it has the same conceptual problems incoporating gravity.

/Fredrik

 

[weirdoguy]

This is not an accurate way of viewing things.

And what is your basis for that claim? Have you studied physics? I mean like 5 years of hard work at Uni, or something equivalent? Or are you just someone who knows some QM and thinks it's enough to tell physicists how they should think? Somehow QM interpretations draw the second type of people in here a lot. And I don't think it's fair to tell me what should I think if one hasn't been through the same hell blessing of studing theoretical physics as I was. Just like you don't go to a doctor and tell them how they should cure their patients.

 

[gentzen]

It is simply that we know standard QM is wrong, eg it predicts the hydrogen states are stationary, so can't jump between them. Yet they do. Interpreting it may be fun and help with interpreting the correct theory (which, as far as we can tell these days, is QFT that explains why the hydrogen states are not stationary), but is ultimately a dead end.

I guess this is mostly a mathematical artifact in this situation, caused by a continuum modeling in time, combined with a "discrete"/finite Hilbert space modelling in space: If couplings like those to the photon-field are neglected, then the state space of a bound electron becomes a finite dimensional Hilbert space.

The issue of this slight modeling mismatch came up recently (17. Juli 2025):

The shift in perspective has a lot to do with the prominent position of time and with physics as a description of "objects." For TomS, it seems a necessary thought that every physical "system" must be in a certain "state" at every point in time. The very concept of "point in time" is questionable in a non-local theory.

Well, a continuum modeling in time actually fits quite well with a continuum modeling in position space. On the other hand, if one believes that one should only work with finite Hilbert spaces, then continuum modeling in time is probably misguided. Therefore, I would be rather cautious about conclusions or paradoxes that follow from this "discrete space" + "continuous time" modeling. So if Sean Carroll were to conclude that the dimension of the Hilbert space is invariant from the beginning of time, assuming it is finite, then he has probably fallen into a trap.
But both quantum computers and consistent histories actually work with discrete time.
And as long as you model spacetime continuously in QFT, you essentially have to model time as continuous as well. If you consider it at all, and not just calculate scattering matrices between asymptotic states.

I later (21. Jul 2025) emphasised that (currently existing) quantum computers work with discrete time:

My main concern is that a quantum computer is discrete in time, even its identity.

in an unrelated question, but for other reasons: I tried to avoid/reduce misconceptions caused by over-idealized models of (currently existing) quantum computers:

The quantum gates are indeed applied sequentially. But a quantum computer usually also has a kind of "operating frequency." So the gates are not only applied sequentially, but their application is also perfectly choreographed.

The final measurement of the "output register" must also be just as perfectly choreographed. If this measurement didn't occur at the only right time, then of course one can still philosophize a lot about what it would have measured had it not been missed. And if one wants, one can simply repeat the experiment and actually measure this time.

 

[syed]

And what is your basis for that claim? Have you studied physics? I mean like 5 years of hard work at Uni, or something equivalent? Or are you just someone who knows some QM and thinks it's enough to tell physicists how they should think? Somehow QM interpretations draw the second type of people in here a lot. And I don't think it's fair to tell me what should I think if one hasn't been through the same hell blessing of studing theoretical physics as I was. Just like you don't go to a doctor and tell them how they should cure their patients.

I have a degree in physics. Secondly, contrary to what you might think, many physicists don't really think about these issues as much since it's just not practical for most day to day things, so being a physicist doesn't necessarily imply that you understand certain interpretations of QM better than others, since quite literally no-one knows what's going on under the hood behind these equations.

Secondly, claiming that someone's intuitions are wrong is also making a claim about physics and in turn reality, yet I don't see you questioning the expertise of the other person I was responding to. Is it only because his views happen to align with yours?

While we're at it, what are your credentials?