Physicists disagree wildly on what quantum mechanics says about reality

[John Clark]

In today's issue of the journal Nature is a report of a survey of physicists that Nature conducted about the meaning of Quantum Mechanics, it's interesting that even after a century there is not something even close to a consensus. Even two physicists who won a Nobel prize for performing an experiment that explores the qualities of quantum reality disagree with each other over what their experiment is trying to tell us.  Another physicist says "The implication [of the survey] is that many quantum researchers simply use quantum theory without engaging deeply with what it means — the ‘shut up and calculate’ approach."

Physicists disagree wildly on what quantum mechanics says about reality

John K Clark    See what's on my new list at  Extropolis

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[Brent Allsop]

It's great that people are at least trying to measure theoretical scientific consensus.

But this type of snapshot survey is the worst.  You have the same issues with people trying to do surveys about what people believe about consciousness. And ultimately, there is a lot about both fields that most people just don't understand, even though there is likely a clear, progressing, scientific consensus on many important beliefs about reality and consciousness.

With this horrible method you have one, or a few people that design the questions, and select the possible answers people can select, which never works at all.  As it says in the article: "Some baulked at the set-up of our questions"  You can tell that almost everyone wanted to say something slightly different from what the possible responses were.

I don't understand why there is not more effort to build and track consensus on this kind of critically important scientific theory in an ongoing way, not just a snapshot.  Rather than just 'peer review' publishing papers, people should be tracking how many people change their beliefs because of such publications/discoveries, and so on, and how many people think published papers are junk, and so on.

We should be able to track the various interpretations, over time, both via the popular consensus, and be able to compare this to the expert consensus.

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[Stuart LaForge]

On Wednesday, July 30, 2025 at 10:45:24 AM UTC-7 johnk...@gmail.com wrote:

In today's issue of the journal Nature is a report of a survey of physicists that Nature conducted about the meaning of Quantum Mechanics, it's interesting that even after a century there is not something even close to a consensus. Even two physicists who won a Nobel prize for performing an experiment that explores the qualities of quantum reality disagree with each other over what their experiment is trying to tell us.  Another physicist says "The implication [of the survey] is that many quantum researchers simply use quantum theory without engaging deeply with what it means — the ‘shut up and calculate’ approach."

Wouldn't the "shut up and calculate" school of thought be covered by the 2% of respondents who who answered "No need for an interpretation"?

Stuart LaForge

[John Clark]

On Wed, Jul 30, 2025 at 3:40 PM Brent Allsop <brent....@gmail.com> wrote:

> You can tell that almost everyone wanted to say something slightly different from what the possible responses were.

Exactly, and that fact tells us something very important. If you conduct a detailed interview with 10 world class physicists on the nature of quantum reality you will find they have 13 entirely different opinions on the subject, most of them unclearly stated, so the scientific community is nowhere near forming a consensus. But they are closer to forming a consensus on that than they are for consciousness! A consciousness "researcher" has nothing equivalent to Bell's Inequality, all he has is the Turing Test and that benchmark became saturated about two years ago, so it is no longer of much use.  I don't think we're ever going to do better than "consciousness is the way data feels when it is being processed intelligently".  

John K Clark  

[Brent Allsop]

Hi John,

You are making a falsifiable claim:  "I don't think we're ever going to be able to do better than that",

While I'm making a different prediction: that there are fundamental qualities out of which subjective experience is "built" or "painted" with neural ponytails which is what computation is.  I'm predicting there will be neural ponytails (like the corpus callosum, not like abstracting senses or communication) which do this subjective building/binding/painting allowing you to directly apprehend redness, which is what computation is.

For example, they will discover which of all our descriptions of stuff in the brain is a description of redness, and nobody will be able to experience that elemental quale without whatever that is, and that whatever that is will always result in the same elemental redness (even though other information bound to that elemental redness may be different, making each person's composite redness experience unique to them)  Experimentalists reliably demonstrating what elemental redness is, and that it is fundamental, using neural ponytails, will falsify your claim to the contrary.

Oh, and there is a significant consensus (evidence for this in Canonizer) that redness is a quality of something in the brain (not a quality of the strawberry) but most lay people aren't getting that message, and idiots are still accepted for publication because nobody is tracking that expert consensus.

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[John Clark]

On Mon, Aug 4, 2025 at 1:00 PM Brent Allsop <brent....@gmail.com> wrote:

Hi Brent:

>> I don't think we're ever going to do better than "consciousness is the way data feels when it is being processed intelligently".  

 

> Hi John,

You are making a falsifiable claim:  "I don't think we're ever going to be able to do better than that", While I'm making a different prediction: that there are fundamental qualities out of which subjective experience is "built" or "painted" with neural ponytails which is what computation is. 

If a particular arrangement of biological neurons (or presumably a corresponding arrangement of semiconductor logic gates) is what generates the redness qualia and is what computation is, then what you are saying is not that far from what I am saying. The major difference between us is that you think a proof is possible but I think that, although true, a proof of it does not exist. We really shouldn't be surprised that in a lofty subject like philosophy there exists true statements that have no proof, after all Kurt Gödel showed that even in a subject as mundane as arithmetic there exists true arithmetical statements that have no proof.  

> I'm predicting there will be neural ponytails (like the corpus callosum, not like abstracting senses or communication) which do this subjective building/binding/painting allowing you to directly apprehend redness, which is what computation is.

I've explained before why I think that would not allow Brent Allsop or John Clark to know what qualia the other apprehended when they observed a ripe strawberry; they both called it "red" but that's just a word in one out of thousands of different human languages. But suppose for the sake of argument we assume somehow that works. Then what? Would your curiosity be satisfied and claim that the thing that turns objective into subjective and vice versa is now fully understandable? Before you made such a bold claim, wouldn't you want to know the details of how the objective is turned into subjective, wouldn't you want to see that marvelous process broken down into a series of small steps that are each as simple as possible before you could say you really understood it?  I remind you that there is no process simpler than the process of turning off to on, or the difference between 0 and 1.

 

> For example, they will discover which of all our descriptions of stuff in the brain is a description of redness, and nobody will be able to experience that elemental quale without whatever that is, and that whatever that is will always result in the same elemental redness

Even if you could prove that a certain arrangement of neurons always produces the same red qualia (and I don't see how that would be possible even in theory, much less in practice) you still haven't proven that arrangement is the only way that red qualia can be produced. 

 

> (even though other information bound to that elemental redness may be different, making each person's composite redness experience unique to them) 

Unique to them? I don't know what you mean by that. Isn't the redness problem solved in your thought experiment?  

> Oh, and there is a significant consensus (evidence for this in Canonizer) that redness is a quality of something in the brain (not a quality of the strawberry)

I would've been very surprised if there wasn't a consensus on that!  Are there really a minority of philosophers that think qualia is in the strawberry and not in the brain?! 

John K Clark

[Brent Allsop]

Hi John,

On Mon, Aug 4, 2025 at 1:51 PM John Clark <johnk...@gmail.com> wrote:

On Mon, Aug 4, 2025 at 1:00 PM Brent Allsop <brent....@gmail.com> wrote:

Hi Brent:

>> I don't think we're ever going to do better than "consciousness is the way data feels when it is being processed intelligently".  

 

> Hi John,

You are making a falsifiable claim:  "I don't think we're ever going to be able to do better than that", While I'm making a different prediction: that there are fundamental qualities out of which subjective experience is "built" or "painted" with neural ponytails which is what computation is. 

If a particular arrangement of biological neurons (or presumably a corresponding arrangement of semiconductor logic gates) is what generates the redness qualia

This is your prediction.  But even if redness is "generated" by neurons or semiconductor logic gates, this will be a verifiable physical fact about physical reality.  In other words, it is just as much a falsifiable claim about fundamental reality as my prediction that the reason glutamate behaves the way it does in a synapse, is because of its redness quality.  We are both simply making competing predictions waiting to be verified by experimental science about what redness is.

Also, you seem to be conflating what I think about qualia and computation.  physical qualities are just physical properties that can represent information "0 and 1"  Physical qualities, alone, can't do computation.   It is the computational binding, which allows a system to be aware of multiple representations at the same time.  Logic gates do this computational binding in a cause and effect way utilizing brute force logic gates, between multiple registers (represented by physical voltages).  Subjective binding computation is different, allowing us to be aware of multiple physical qualities at the same time, and these united gestalt qualities we are aware of are like something.

 

and is what computation is, then what you are saying is not that far from what I am saying. The major difference between us is that you think a proof is possible but I think that, although true, a proof of it does not exist. We really shouldn't be surprised that in a lofty subject like philosophy there exists true statements that have no proof, after all Kurt Gödel showed that even in a subject as mundane as arithmetic there exists true arithmetical statements that have no proof.  

> I'm predicting there will be neural ponytails (like the corpus callosum, not like abstracting senses or communication) which do this subjective building/binding/painting allowing you to directly apprehend redness, which is what computation is.

I've explained before why I think that would not allow Brent Allsop or John Clark to know what qualia the other apprehended when they observed a ripe strawberry; they both called it "red" but that's just a word in one out of thousands of different human languages. But suppose for the sake of argument we assume somehow that works. Then what? Would your curiosity be satisfied and claim that the thing that turns objective into subjective and vice versa is now fully understandable?

Your statement about "turns subjective into objective" seems to be communicating to me that I'm still failing to communicate what we're predicting 'subjective' is.   Think about what a quality like redness is.  Cause and effect based observation can 'detect', 'describe', 'name' qualities, but since all of that is abstract "0 and 1" it's all just another name, as you say.  It's not like anything.  Abstract communication/detection can only describe the qualities.  In order to know what a redness quality is like, you need some other mechanism that will enable you to directly apprehend multiple qualities at the same time - something different from cause and effect based observation.  We observe the causes and effects of how the neurons are doing this binding, we just don't yet realize what those qualities are like we are observing.  Subjective isn't different from objective, it is all the same thing.  The only important part is how you are observing what is going on, subjective binding or cause and effect base detection (with the required dictionary).

 

Before you made such a bold claim, wouldn't you want to know the details of how the objective is turned into subjective, wouldn't you want to see that marvelous process broken down into a series of small steps that are each as simple as possible before you could say you really understood it?  I remind you that there is no process simpler than the process of turning off to on, or the difference between 0 and 1.

 

> For example, they will discover which of all our descriptions of stuff in the brain is a description of redness, and nobody will be able to experience that elemental quale without whatever that is, and that whatever that is will always result in the same elemental redness

Even if you could prove that a certain arrangement of neurons always produces the same red qualia (and I don't see how that would be possible even in theory, much less in practice) you still haven't proven that arrangement is the only way that red qualia can be produced. 

 

> (even though other information bound to that elemental redness may be different, making each person's composite redness experience unique to them) 

Unique to them? I don't know what you mean by that. Isn't the redness problem solved in your thought experiment?

Yes, you still seem to be conflating elemental qualities with gestalt composite qualities.  The prediction is that there are fundamental qualities which can be subjectively bound into unified gestalt composite experiences.  Brent Allsop can't know what John Clarks composite redness qualia experience is like, as you say.  because a composite redness experience is very complex and must be composed of many different memories and such represented by different physical things all bound together.  But there is a fundamental level (simple and similar to "0 and 1") which can be represented by one thing.  Elemental redness is like that, a particular elemental redness, like a 1, is very simple, one thing, and the same for everyone.   If you have a dictionary (i.e. you know the true color qualities of things) then you can eff the ineffable nature of an alemental quale with abstract communication.  There is no difference between subjective and objective there is just two different ways to observe physical reality.  One that tells you, directly, what it is like, and the other which requires a dictionary to know what we are observing.

 

> Oh, and there is a significant consensus (evidence for this in Canonizer) that redness is a quality of something in the brain (not a quality of the strawberry)

I would've been very surprised if there wasn't a consensus on that!  Are there really a minority of philosophers that think qualia is in the strawberry and not in the brain?! 

John K Clark

 

> You can tell that almost everyone wanted to say something slightly different from what the possible responses were.

Exactly, and that fact tells us something very important. If you conduct a detailed interview with 10 world class physicists on the nature of quantum reality you will find they have 13 entirely different opinions on the subject, most of them unclearly stated, so the scientific community is nowhere near forming a consensus. But they are closer to forming a consensus on that than they are for consciousness! A consciousness "researcher" has nothing equivalent to Bell's Inequality, all he has is the Turing Test and that benchmark became saturated about two years ago, so it is no longer of much use.  I don't think we're ever going to do better than "consciousness is the way data feels when it is being processed intelligently".  

John K Clark  

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[John Clark]

On Mon, Aug 4, 2025 at 5:07 PM Brent Allsop <brent....@gmail.com> wrote:

>> If a particular arrangement of biological neurons (or presumably a corresponding arrangement of semiconductor logic gates) is what generates the redness qualia

> This is your prediction. But even if redness is "generated" by neurons or semiconductor logic gates, this will be a verifiable physical fact about physical reality. 

I'm about 99% certain a fact about physical reality is that redness is generated by neurons or semiconductor logic gates, but I'm 100% certain it is NOT a verifiable physical fact about physical reality. I don't see any way, even in theory, it could ever be proven or disproven. And I'm curious why you felt the need to use scare quotes in the above.
 

In other words, it is just as much a falsifiable claim about fundamental reality as my prediction that the reason glutamate behaves the way it does in a synapse, is because of its redness quality. 

Suppose for the sake of argument you somehow (I can't imagine how) proved that glutamate caused the redness quality, I don't think that would satisfy your curiosity concerning the objective/subjective divide, it certainly wouldn't satisfy mine. It's an objective fact that glutamate is a simple amino acid composed of just 19 atoms, I'd want to understand all the steps in the process that enable it to jump over the objective/subjective gap and produce such a vivid subjective effect. And what does it mean to "understand" something? 

I think if you can break down something that is complex and mysterious into parts  that are less complex and less mysterious then you have gained some understanding. The ultimate in understanding would be if the parts were as simple as it's possible to be, and there is nothing simpler than a part that can change it only one way, like off to on, or 0 to 1.

 

> We are both simply making competing predictions waiting to be verified by experimental science about what redness is.

The only prediction I'm making is that during the next thousand years consciousness research will make the same amount of progress that it has made during the last thousand years, and that would be zero. Meanwhile, intelligence research has made a gargantuan amount of progress in just the last two years, and there's no signs of that rate of progress slowing down. 

 

> Physical qualities, alone, can't do computation. 

I strongly disagree. Physical qualities are the only thing that can do computations because information is physical; it takes physical energy to erase information and information has entropy, both thermodynamic entropy and Shannon information entropy have the same mathematical form.

 

 > Logic gates do this computational binding in a cause and effect way utilizing brute force logic gates, between multiple registers (represented by physical voltages).  Subjective binding computation is different,

Different? Not very different! To change one into the other all I need to do is change the words "logic gates" to "connected neurons" in the above. That's it.  I wouldn't even need to change "physical voltages" because physical voltages also play a key part in the operation of neurons. 

 

> Cause and effect based observation can 'detect', 'describe', 'name' qualities, but since all of that is abstract "0 and 1" it's all just another name, as you say.  It's not like anything.

If electrical engineering knowledge is "just abstract" why isn't biological knowledge also "just abstract"?

 

 > Abstract communication/detection can only describe the qualities.  In order to know what a redness quality is like, you need some other mechanism that will enable you to directly apprehend multiple qualities at the same time - something different from cause and effect  

 If something didn't happen because of cause and effect then there is only one conclusion you can make if you value logic and the scientific method, it was random. But I don't think going down that path is going to help you understand the fundamental nature of consciousness. And that is exactly why consciousness research has made zero progress over the last century, or even the last millennium for that matter, but intelligence research is radically changing the world. 

 

>>> (even though other information bound to that elemental redness may be different, making each person's composite redness experience unique to them) 

 >>Isn't the redness problem solved in your thought experiment?

> Yes, you still seem to be conflating elemental qualities with gestalt composite qualities. The prediction

A prediction is a statement that can be proven or disproven after a finite amount of time, but you are not doing that, you are making a statement not a prediction. 

 

> is that there are fundamental qualities which can be subjectively bound into unified gestalt composite experiences.  Brent Allsop can't know what John Clarks composite redness qualia experience is like, as you say.  because a composite redness experience is very complex and must be composed of many different memories and such represented by different physical things all bound together. 

So regardless of what the fundamental qualities are, what we apprehend when we look at a ripe strawberry is a "gestalt composite experience" and thus your red qualia is NOT the same as my red qualia, and the word "glutamate" is never going to be the key to understanding. 

 > If you have a dictionary (i.e. you know the true color qualities of things)

So glutamate is the true color of the redness qualia? I don't know what that means. I also don't know how you could ever derive such a dictionary, even in theory.

John K Clark

[Will Steinberg]

Lol yes, what that guy doesn’t realize that what he is really saying is just “people who disagree with me are wrong.”

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[Lawrence Crowell]

This survey illustrates that the Copenhagen interpretation is most popular. I have sympathies with that as well, though I am not devoted to it. Niels Bohr advanced the idea that there is a correspondence between classical observables and quantum observables and their outcomes. This is a dualist world perspective, which some people dislike because it rankles with the idea that all is quantum. However, string theory has quantum gravitation on a classical background, while loop quantum gravitation has a putative all quantum spin-net approach that so far appears unworkable. I tend towards the more ψ-epistemic interpretations but have some interest in the many worlds interpretation that is ψ-ontological.

It has been my thinking the apparat quantum interpretations are auxiliary postulates or physical axioms that are imposed on quantum mechanics. I think a good interpretation is one that is not derivable from basic quantum physical postulates and is then only falsifiable with quantum theory. Such quantum interpretations are then unobservable or undecidable based on both experimental outcomes and formal derivations with quantum theory. This means quantum interpretations are at best only useful with preferably a minimal amount of excess baggage. They may serve as explanatory heuristics for certain problems or in certain presentations.

Copenhagen interpretation involves the concept of complementarity. Bohr stated that the world is a dualism between the quantum world and the classical world. This dualism extended to how operators in quantum mechanics acted on quantum state vectors to define eigenvalues, easily constructed in matrix form via diagonalization, that are reflected in the classical world as what is observed. A measurement, or in more modern construction decoherence and einselection, the outcome is defined classically with a macroscopic system or apparatus. This is dualism between the quantum operator or observable and the classical observable that has a correspondence with action S = Nħ, for N →∞. The actual limit to infinity is a fiction, such as the onset of superconductivity needs not an infinite number of electrons, as spelled out in theory, to occur. Einselection is a large number limit for quantum numbers to become stable against quantum and thermal noise. In this quantum observables are only real according to their classical correspondence and their occurrence in a classical context, such as with a measurement by a macroscopic or classical apparatus.

A related ψ-epistemic interpretation is information based and framed around updates on information. This dispenses with complementarity or relegates it to a minor role. Quantum measurements are then a process of “20 questions,” where the act of measurements informs the experimenter on the nature of the quantum system, but there is nothing intrinsic to the quantum wave or reality. There is then in effect no reality to quantum states, which is shared by the Copenhagen interpretation. In the Copenhagen interpretation reality is classical or the decoherent/measurement outcome of a quantum state reduction. With this QuBism approach without appealing to a classical world the only frame is the observer itself. In the end everything is utterly subjective and considered to be in a Bayes theorem sense. The difficulty though is that this leads to a sort of solipsism. In a world where the quantum state is unreal, if there is no complementarity there is then no ontological stance for classical observables or the macroscopic world. Reality is then purely a matter of the subjective judgment of the observer.

The dominant ψ-ontological interpretation is the Everettian or Many Worlds Interpretation (MWI). This says that there is no collapse or reduction of a wave function. The superposition of states continues, but an observer can only report one of those eigenstates, and the world splits into branches correspond to the set of possible outcomes. This replaces the reduction or collapse of a state with a phenomenological interpretation of an observer of only one outcome with the entire world ultimately in a superposition of entangled states with the apparatus or needle state. There is no “here” where the world splits. This has the advantage of a sort of nonlocality that would be good for quantum gravitation. However, this still just replaces a mysterious collapse with a split. It also means the world splits into a Yggdrasil set of outcomes that exponentially grows.

People have been trying to derive Born rule with WMI, and so for the effort is inconclusive. Sean Carroll has been pursuing this effort, and it is becoming snagged into a growing briar patch of difficulties. In the end the problem is that with this branching approach to ontology the number of branches increases exponentially. Suppose a 2-state system, then if you make n measurements then there are N = 2^n possible branchings. Then consider this sequence of branched outcomes as a binary code. As n becomes large these binary strings increase. Further, if we want an accounting or computing system, think a Turing machine that can enumerate all of these within a single algorithm, this runs into Chaitan’s Turing probability. This is an incomputable system.

This would not mean many worlds is false, but rather that it is not a workable system to solve certain problems. I do not think it solves the Born rule as some consequence of QM plus MWI.

These are the interpretations I will look at closely here. There are others and quantum interpretations have begun to populate the theoretical landscape like a population boom of bunnies. I will conclude by saying that largely we can do physics with a minimum of these considerations. I think most work on physics leans on “shut up and calculate and measure.” The problem is that we cannot say at all what the physical state of a system is prior to a measurement. Outside of the quantum Zeno effect, where measurements are taken in rapid succession, there is no meaning to say that a quantum wave is in any such state, but rather a summation of probability amplitudes. The quantum Zeno effect skirts this issue by measuring on a time scale T << 1/ν, for ν the frequency of the system. The wave function has little time to evolve after any measurement, so we have a near unit probability of knowing what the state is prior to a measurement for a measurement take a time T >> 1/ν after preparation of a quantum state or prior measurement it is meaningless to say the quantum wave for state can be specified.

The matter may have less to do with outcomes as answers given by nature, but the sort of questions we ask. Certain questions are simply meaningless.

LC

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[John Clark]

On Wed, Aug 6, 2025 at 5:34 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> quantum interpretations are at best only useful with preferably a minimal amount of excess baggage [...] Bohr stated that the world is a dualism between the quantum world and the classical world.

Yes, Bohr thought there were two sets of fundamental laws of physics, one set works for things that have been measured, and the other set of fundamental laws works for things that have not been measured, and he was very vague about exactly what this all powerful thing called a "measurement" actually is. But Hugh Everett disagreed, he said things were simpler than that, there is only one set of fundamental physical laws and they can be found in Schrodinger's equation, and that equation contains nothing about collapsing. Many Worlds is bare bones, no nonsense quantum mechanics. 

> However, this [Many Worlds] still just replaces a mysterious collapse with a split. 

The difference is the Copenhagen postulated collapse really is mysterious, but the Many World's split is not, there is even an equation that describes it EXACTLY. The Copenhagen and Bayesian interpretations work fine if you're only interested in predicting what number the needle on your voltmeter is going to point to, but if you want to find something new in quantum mechanics you're going to need to form some sort of mental picture of what's going on, and neither of those two things could do that, but Many Worlds can.

> In the end the problem is that with this branching approach to ontology the number of branches increases exponentially.Suppose a 2-state system, then if you make n measurements then there are N = 2^n possible branchings. Then consider this sequence of branched outcomes as a binary code. As n becomes large these binary strings increase. Further, if we want an accounting or computing system, think a Turing machine that can enumerate all of these within a single algorithm, this runs into Chaitan’s Turing probability. This is an incomputable system.

If Many worlds is correct then any change, no matter how small, causes the universe to split, but the vast majority of those changes have a negligible effect on the conscious experience of a scientist doing a quantum mechanical experiment to investigate the nature of reality. The only difference between two universes might be that in one a micrometeorite smaller than a bacteria hits the planet Pluto, but in the other it does not; Pluto is very slightly different but the conscious experience of the scientist in both universes is identical.

So even though there are an infinite number of branches we could group them together into a finite number of sets of universes such that even though all the elements of that set are slightly different they all produce the same conscious state for a scientist conducting the experiment. After all they are an infinite number of points in a foot but you can group all those infinite points into a finite number,12. The first set of points all have the property of being in the first inch, the second set of points all have the property of being in the second inch, and so on all the way to 12.    

 

> This would not mean many worlds is false, but rather that it is not a workable system to solve certain problems.

Many Worlds works as well as Copenhagen or Bayes on most problems and better on some. 

>  I think most work on physics leans on “shut up and calculate and measure.”

That could change if quantum computers become practical because if you're going to write a long complicated program that is made to run on a quantum computer  you're going to need to form some sort of mental picture about what's going on, and "shut up and calculate" can't do that.  

John K Clark

 

[Lawrence Crowell]

On Wed, Aug 6, 2025 at 12:22 PM John Clark <johnk...@gmail.com> wrote:

On Wed, Aug 6, 2025 at 5:34 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> quantum interpretations are at best only useful with preferably a minimal amount of excess baggage [...] Bohr stated that the world is a dualism between the quantum world and the classical world.

Yes, Bohr thought there were two sets of fundamental laws of physics, one set works for things that have been measured, and the other set of fundamental laws works for things that have not been measured, and he was very vague about exactly what this all powerful thing called a "measurement" actually is. But Hugh Everett disagreed, he said things were simpler than that, there is only one set of fundamental physical laws and they can be found in Schrodinger's equation, and that equation contains nothing about collapsing. Many Worlds is bare bones, no nonsense quantum mechanics. 

The MWI has this problem with the phenomenology of a single path experienced by an observer. This splitting of amplitudes into local classical-like, according to any observer "frame dragged" along one path, is external to the postulates of QM. This is a feature of all quantum interpretations; they all involve ancillary postulates added onto QM in order to make the issue of quantum decoherence conform to our "classical brain" understanding of things. 

 

> However, this [Many Worlds] still just replaces a mysterious collapse with a split. 

The difference is the Copenhagen postulated collapse really is mysterious, but the Many World's split is not, there is even an equation that describes it EXACTLY. The Copenhagen and Bayesian interpretations work fine if you're only interested in predicting what number the needle on your voltmeter is going to point to, but if you want to find something new in quantum mechanics you're going to need to form some sort of mental picture of what's going on, and neither of those two things could do that, but Many Worlds can.

The idea is that on some global level, that is honestly unobservable, quantum superpositions or entanglements remain. There is no loss of quantum phase. This is something I tend to agree with, but this does not require MWI. Decoherence can just mean that a quantum phase is distributed from a known system into a reservoir of other states not well specified. As a result there is for an observer with limited resources a coarse grained and stochastic phenomenology. Further, the density matrix for the known system with the loss of its quantum phase and the attenuation of off-diagonal elements is reduced to a diagonal set of entries that describe a classical probability distribution. This is a part of the idea of a measurement being the transduction of a quantum system into a classical system with coupling to an apparatus or a large number of statistically mixed states. This does not predict what the actual outcome will be. The actual observation or the phenomenology of the classical-like world based on an actual outcome is not predictable. You can invoke collapse or MWI splitting, but in both cases this is just an ancillary assumption.

 

> In the end the problem is that with this branching approach to ontology the number of branches increases exponentially.Suppose a 2-state system, then if you make n measurements then there are N = 2^n possible branchings. Then consider this sequence of branched outcomes as a binary code. As n becomes large these binary strings increase. Further, if we want an accounting or computing system, think a Turing machine that can enumerate all of these within a single algorithm, this runs into Chaitan’s Turing probability. This is an incomputable system.

If Many worlds is correct then any change, no matter how small, causes the universe to split, but the vast majority of those changes have a negligible effect on the conscious experience of a scientist doing a quantum mechanical experiment to investigate the nature of reality. The only difference between two universes might be that in one a micrometeorite smaller than a bacteria hits the planet Pluto, but in the other it does not; Pluto is very slightly different but the conscious experience of the scientist in both universes is identical.

You are using a coarse grain argument to brush over the problem. By doing that you are breaking the unitarity of QM, even if slightly. The branching of quantum superpositions according to all possible locally observable outcomes is uncomputable as a form of Chaitin's halting probability. 

 

So even though there are an infinite number of branches we could group them together into a finite number of sets of universes such that even though all the elements of that set are slightly different they all produce the same conscious state for a scientist conducting the experiment. After all they are an infinite number of points in a foot but you can group all those infinite points into a finite number,12. The first set of points all have the property of being in the first inch, the second set of points all have the property of being in the second inch, and so on all the way to 12.    

 

> This would not mean many worlds is false, but rather that it is not a workable system to solve certain problems.

Many Worlds works as well as Copenhagen or Bayes on most problems and better on some. 

>  I think most work on physics leans on “shut up and calculate and measure.”

That could change if quantum computers become practical because if you're going to write a long complicated program that is made to run on a quantum computer  you're going to need to form some sort of mental picture about what's going on, and "shut up and calculate" can't do that.  

The only reason for this mental picture, one that cannot be empirically tested, is to make one feel better. It is a sort of crutch or training wheel set to assuage a level of uncertainty or loss of ontological groundedness.

LC

 

John K Clark

 

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[John Clark]

On Thu, Aug 7, 2025 at 9:59 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> The MWI has this problem with the phenomenology of a single path experienced by an observer.

I agree it would be inconsistent with experimental results if there was only one path and only one observer, but not if there were as many paths as there were that did not violate Schrödinger's Equation, and an equal number of observers to observe them. 

 

> This splitting of amplitudes into local classical-like, according to any observer "frame dragged" along one path, is external to the postulates of QM.

Nobody is being dragged to the one true path, instead there is an astronomical, possibly infinite, number of paths that are all equally real and a real observer to observe everyone of them.   

> You can invoke collapse or MWI splitting, but in both cases this is just an ancillary assumption.

Schrodinger's equation says nothing about the wave collapsing so if you want to have that you've got to tack on an additional assumption, but that's not the case for splitting, that comes about naturally. An electron can have many different positions and have many different velocities but the equation does not say that one particular position or one particular velocity is more real than the others, and I know what "real" is supposed to mean from everyday experience therefore, assuming only that Schrodinger's equation is correct, the only way those two facts can be reconciled is if there is a John Clark observing that electron having every position and velocity that is not forbidden by the laws of physics. The only assumption Many Worlds makes is that Schrodinger's Equation means what it says.

>> If Many worlds is correct then any change, no matter how small, causes the universe to split, but the vast majority of those changes have a negligible effect on the conscious experience of a scientist doing a quantum mechanical experiment to investigate the nature of reality. The only difference between two universes might be that in one a micrometeorite smaller than a bacteria hits the planet Pluto, but in the other it does not; Pluto is very slightly different but the conscious experience of the scientist in both universes is identical.

> You are using a coarse grain argument to brush over the problem. By doing that you are breaking the unitarity of QM, even if slightly.

But I'm lumping universes together such that, although they're all slightly different, the conscious state of the experimenter is exactly identical in all of them, therefore if it does violate unitarity then that violation is so small as to be completely unobservable even in theory, much less in practice. 

>>>  I think most work on physics leans on “shut up and calculate and measure.”

>> That could change if quantum computers become practical because if you're going to write a long complicated program that is made to run on a quantum computer  you're going to need to form some sort of mental picture about what's going on, and "shut up and calculate" can't do that.  

> The only reason for this mental picture, one that cannot be empirically tested, is to make one feel better.

I think a mental picture can do more than make you feel good, even if they are not precise. Many of the greatest physicists in history thought in pictures. Faraday's lines of force is not completely correct but it was good enough for Maxwell to come up with his equations. And Einstein came up with both Special and General relativity by first forming a mental picture in his mind, the equations came later. The same is true for Richard Feynman, you can do quantum mechanical calculations without his diagrams but it makes life a lot easier if you use them.  

John K Clark

 

[Lawrence Crowell]

On Thu, Aug 7, 2025 at 1:08 PM John Clark <johnk...@gmail.com> wrote:

On Thu, Aug 7, 2025 at 9:59 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> The MWI has this problem with the phenomenology of a single path experienced by an observer.

I agree it would be inconsistent with experimental results if there was only one path and only one observer, but not if there were as many paths as there were that did not violate Schrödinger's Equation, and an equal number of observers to observe them. 

 

> This splitting of amplitudes into local classical-like, according to any observer "frame dragged" along one path, is external to the postulates of QM.

Nobody is being dragged to the one true path, instead there is an astronomical, possibly infinite, number of paths that are all equally real and a real observer to observe everyone of them.   

This all begins to sound the same as Bohm's active vs inactive channels. The observer is in a sense frame dragged along a path in Hilbert or Fubini-Study space corresponding to a certain outcome. Somehow, by the magic of consciousness or something, the observer only experiences one path. This really is not that different from collapse.

 

> You can invoke collapse or MWI splitting, but in both cases this is just an ancillary assumption.

Schrodinger's equation says nothing about the wave collapsing so if you want to have that you've got to tack on an additional assumption, but that's not the case for splitting, that comes about naturally. An electron can have many different positions and have many different velocities but the equation does not say that one particular position or one particular velocity is more real than the others, and I know what "real" is supposed to mean from everyday experience therefore, assuming only that Schrodinger's equation is correct, the only way those two facts can be reconciled is if there is a John Clark observing that electron having every position and velocity that is not forbidden by the laws of physics. The only assumption Many Worlds makes is that Schrodinger's Equation means what it says.

All that Schrodinger's equation tells you is there is an evolution of superposed amplitudes that correspond by modulus square to a probability. It does not tell you which outcome happens. There is nothing one can glean from such data whether there is an actual objective state to the system prior to the measurement. To ask why an outcome occurs, or how it is that a measurement is what it is, is to ask an irrelevant question. This is a metaphysical issue and not something appropriate to physics.

 

>> If Many worlds is correct then any change, no matter how small, causes the universe to split, but the vast majority of those changes have a negligible effect on the conscious experience of a scientist doing a quantum mechanical experiment to investigate the nature of reality. The only difference between two universes might be that in one a micrometeorite smaller than a bacteria hits the planet Pluto, but in the other it does not; Pluto is very slightly different but the conscious experience of the scientist in both universes is identical.

> You are using a coarse grain argument to brush over the problem. By doing that you are breaking the unitarity of QM, even if slightly.

But I'm lumping universes together such that, although they're all slightly different, the conscious state of the experimenter is exactly identical in all of them, therefore if it does violate unitarity then that violation is so small as to be completely unobservable even in theory, much less in practice. 

I generally do not bring consciousness into physics problems and theory. 

Given n measurements of a 2-state system, there are 2^n possible sets of outcomes. This Markov branching set of possibilities means the local operators in classical computation (LOCC), sometimes called Stochastic LOCC or SLOCC, computes this as an outcome. Prior to a measurement there is no actual computation, contrary to what we often naively think with quantum computers, or computation output and so this problem is in effect removed as a "logarithm" of this with a set of n configurations.We might consider measurements as an entanglement and all this would entail in a purely quantum setting in an n-tanglement. Yet with or without MWI outcomes are LOCC, and within MWI there is effectively a computation output according to an observer. For the universe at large with n → ∞, there is an implicit power set realization. By Chaitin's incomputable halting probability this is undecidable by Godel's first theorem. 

 

>>>  I think most work on physics leans on “shut up and calculate and measure.”

>> That could change if quantum computers become practical because if you're going to write a long complicated program that is made to run on a quantum computer  you're going to need to form some sort of mental picture about what's going on, and "shut up and calculate" can't do that.  

> The only reason for this mental picture, one that cannot be empirically tested, is to make one feel better.

I think a mental picture can do more than make you feel good, even if they are not precise. Many of the greatest physicists in history thought in pictures. Faraday's lines of force is not completely correct but it was good enough for Maxwell to come up with his equations. And Einstein came up with both Special and General relativity by first forming a mental picture in his mind, the equations came later. The same is true for Richard Feynman, you can do quantum mechanical calculations without his diagrams but it makes life a lot easier if you use them.  

Feynman diagrams have a one to one correspondence to a scattering amplitude. The branching of the universe into a Yggdrasil tree of outcomes has no correspondence with something that is measurable. 

LC 

 

John K Clark

 

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[Stuart LaForge]

On Wed, Aug 6, 2025 at 2:34 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

This survey illustrates that the Copenhagen interpretation is most popular. I have sympathies with that as well, though I am not devoted to it. Niels Bohr advanced the idea that there is a correspondence between classical observables and quantum observables and their outcomes. This is a dualist world perspective, which some people dislike because it rankles with the idea that all is quantum. However, string theory has quantum gravitation on a classical background, while loop quantum gravitation has a putative all quantum spin-net approach that so far appears unworkable. I tend towards the more ψ-epistemic interpretations but have some interest in the many worlds interpretation that is ψ-ontological.

 

My problem with an epistemic wavefunction is that it makes quantum mechanics weirder and spookier than it needs to be. If the wavefunction is just some mathematical tool that allows people to predict probability distributions that particle states are drawn from, then that necessarily entails some mysterious physical mechanism, including memory and information processing, by which particle states are coordinated and constrained to follow those probabilities. When any given quantum state is measured for a particle, that particular state has to somehow "know" about the probabilities of all the other possible, but counterfactual, particle states that were not measured. It is like the measured state is entangled with all the counterfactual states, but how is that possible if the counterfactual states are merely imaginary figments of an epistemic wavefunction that only exists in your head? It would mean that particles would have to be able to access the epistemic wavefunction in your head and that would imply that particles have telepathy and are able to do abstract math which seems to me at best like panpsychism, and at worse like superdeterminism in the sense the entire universe is acting like Descartes's Evil Demon and trying to con you into believing that you have such a thing as a choice that was not predestined since the moment of the big bang.

Let me give a classical example to illustrate what I mean. When you roll a normal six-sided die, the probability that you roll a 6 is 1/6. The physical mechanism by which the 6 knows how often to come up is that the die is ontological and has six faces of equal area, so the frequency of observation of 6s is physically constrained by the geometric fact that the counterfactual faces 1-5 exist and shape the probability distribution even when they are not the number that gets rolled. Now imagine how weird it would be if you had an epistemic die where one and only one face somehow came into existence the moment you rolled it. And yes, a simulated die running on your phone could do that, but we are using dice as a model of what are supposed to be the wave functions of  actual ontologically existent particles. Epistemic wave functions are parsimonious so they act like simulations under tight resource constraints of computability. The moon is a mathematical abstraction that does not waste resources becoming real until you happen to look at it, just like a video game.

On the other hand, if you accept the extravagance of the infinity that an ontological wave function affords, then when your favorite electron is spin up in this universe, then its wave function is in phase with the you that measures it be up and out of phase with the you that measures it to be spin down.

It has been my thinking the apparat quantum interpretations are auxiliary postulates or physical axioms that are imposed on quantum mechanics. I think a good interpretation is one that is not derivable from basic quantum physical postulates and is then only falsifiable with quantum theory. Such quantum interpretations are then unobservable or undecidable based on both experimental outcomes and formal derivations with quantum theory. This means quantum interpretations are at best only useful with preferably a minimal amount of excess baggage. They may serve as explanatory heuristics for certain problems or in certain presentations.

My research into the hypothesis I discussed earlier that the Hubble tension might be caused by a double rotation of the Hubble sphere in 4-D Euclidean space, the SO(4) group, resulted in some very interesting insights. I have concluded that even classical physics in the form of special and general relativity both predict multiverses in distinct ways. That means that the only extant physical theory that does not directly or indirectly imply or predict a multiverse, at least in some "interpretation", is Newtonian mechanics. Take the following examples:

1. Special Relativity:

All of SR and can be can be recapitulated by the hypothesis that matter are those particles that go at the speed of light along worldlines that are more or less locally parallel to the axis that 4th dimension of Euclidean space, with the angle made by the worldline or 4-vector of the particle to the W or proper time axis is θ = arcsin(β). These matter particles move at the speed of light along the W axis, while photons go at c in the familiar X,Y, and Z of 3-space. Lorentz transformations between IRFs can be performed with the additional step of a Wick rotation, but time dilation and length contraction can be directly demonstrated without WIck rotation. Essentially the proper time from the Minkowski space-time invariant becomes the time coordinate of a particle's 4-vector, and the Euclidean invariant sum of squares is treated as a universal cosmic time like the comoving proper time from the FLRW metric.

If you accept that a Wick rotation maps Minkowski 3+1 space-time to 4-D space with a 1:1 function then it becomes apparent There are at least 4 or if you count antimatter universes, 8 parallel universes, because the symmetry of the space is such that there is no reason why the X, Y, and Z axes cannot each host their proper time axis for the particles going at c along each of those spatial axes. Of course as usual, for me, someone has already figured this out.

https://arxiv.org/abs/physics/0410054

But yeah, the Euclidean or Proper Time "interpretation" of Special Relativity, predicts a multiverse composed of universes with orthogonal proper time axes.

2. General Relativity:

The maximal analytic extension of the Penrose diagram for any black hole metric gives rise to several parallel universes separated by event horizons or wormholes.

https://jila.colorado.edu/~ajsh/insidebh/penrose.html

3. Inflation Theory

Eternal Inflation predicts that the infinite inflaton field eternally decays or undergoes a phase change into local big bang bubble universes each complete with their own space-times all over what can only be called a multiverse. https://arxiv.org/abs/hep-th/0702178

4. Standard Model of Particle Physics

The Standard Model cannot adequately explain the fine-tuning of Higg's field and fine structure constant necessary to allow for matter that is capable of giving rise to complex intelligent life to form except through the anthropic principle which implies a multiverse replete with a massive population of all manner of universes of which this universe seems to be a highly unlikely sample.

5. String Theory:

I am not really a huge fan of it, but it also predicts the existence of a multiverse composed of more than 10^120 universes.

 

Copenhagen interpretation involves the concept of complementarity. Bohr stated that the world is a dualism between the quantum world and the classical world. This dualism extended to how operators in quantum mechanics acted on quantum state vectors to define eigenvalues, easily constructed in matrix form via diagonalization, that are reflected in the classical world as what is observed. A measurement, or in more modern construction decoherence and einselection, the outcome is defined classically with a macroscopic system or apparatus. This is dualism between the quantum operator or observable and the classical observable that has a correspondence with action S = Nħ, for N →∞. The actual limit to infinity is a fiction, such as the onset of superconductivity needs not an infinite number of electrons, as spelled out in theory, to occur. Einselection is a large number limit for quantum numbers to become stable against quantum and thermal noise. In this quantum observables are only real according to their classical correspondence and their occurrence in a classical context, such as with a measurement by a macroscopic or classical apparatus.

Well, yes. Copenhagen is a very dualistic interpretation where particles exist in a spirit realm of invisible superposition, until summoned into existence somewhere by measurement or observation. Trillions upon trillions of galaxies extending out further than we can ever see, even in theory, and the universe is too stingy to give a particle a position or a momentum until you look at it, and even then only one of those at a time.

 

A related ψ-epistemic interpretation is information based and framed around updates on information. This dispenses with complementarity or relegates it to a minor role. Quantum measurements are then a process of “20 questions,” where the act of measurements informs the experimenter on the nature of the quantum system, but there is nothing intrinsic to the quantum wave or reality. There is then in effect no reality to quantum states, which is shared by the Copenhagen interpretation. In the Copenhagen interpretation reality is classical or the decoherent/measurement outcome of a quantum state reduction. With this QuBism approach without appealing to a classical world the only frame is the observer itself. In the end everything is utterly subjective and considered to be in a Bayes theorem sense. The difficulty though is that this leads to a sort of solipsism. In a world where the quantum state is unreal, if there is no complementarity there is then no ontological stance for classical observables or the macroscopic world. Reality is then purely a matter of the subjective judgment of the observer.

I consider myself a Bayesian, but the evidence from all the physical theories that predict a multiverse gives MWI more weight than Qubism in my posterior distribution.

 

The dominant ψ-ontological interpretation is the Everettian or Many Worlds Interpretation (MWI). This says that there is no collapse or reduction of a wave function. The superposition of states continues, but an observer can only report one of those eigenstates, and the world splits into branches correspond to the set of possible outcomes. This replaces the reduction or collapse of a state with a phenomenological interpretation of an observer of only one outcome with the entire world ultimately in a superposition of entangled states with the apparatus or needle state. There is no “here” where the world splits. This has the advantage of a sort of nonlocality that would be good for quantum gravitation. However, this still just replaces a mysterious collapse with a split. It also means the world splits into a Yggdrasil set of outcomes that exponentially grows.

But Yggdrasil never splits, it only ever branches. From trunk to twig, it is only ever one connected tree or Directed Acyclic Graph (DAG). It might be uncomputable but that would not make it any less true.

People have been trying to derive Born rule with WMI, and so for the effort is inconclusive. Sean Carroll has been pursuing this effort, and it is becoming snagged into a growing briar patch of difficulties. In the end the problem is that with this branching approach to ontology the number of branches increases exponentially. Suppose a 2-state system, then if you make n measurements then there are N = 2^n possible branchings. Then consider this sequence of branched outcomes as a binary code. As n becomes large these binary strings increase. Further, if we want an accounting or computing system, think a Turing machine that can enumerate all of these within a single algorithm, this runs into Chaitan’s Turing probability. This is an incomputable system.

How so? It seems to me that the Born rule is the natural and intuitive result of frequentist statistics being applied to all the various Everrett branches of the multiverse. ok, so exponential growth is hard to compute. Why does it matter that the infinite multiverse is an incomputable system? The smallest positive real number is incomputable too, but that does not make real numbers any less real or any less useful. Epistemic ψ- theories, might be computable, but that implies the universe is a parsimonious simulation and that the simulator is trying to save RAM and compute cycles.

 

This would not mean many worlds is false, but rather that it is not a workable system to solve certain problems. I do not think it solves the Born rule as some consequence of QM plus MWI.

These are the interpretations I will look at closely here. There are others and quantum interpretations have begun to populate the theoretical landscape like a population boom of bunnies. I will conclude by sayin

 

The quantum Zeno effect skirts this issue by measuring on a time scale T << 1/ν, for ν the frequency of the system. The wave function has little time to evolve after any measurement, so we have a near unit probability of knowing what the state is prior to a measurement for a measurement take a time T >> 1/ν after preparation of a quantum state or prior measurement it is meaningless to say the quantum wave for state can be specified.

The matter may have less to do with outcomes as answers given by nature, but the sort of questions we ask. Certain questions are simply meaningless.

I believe that rather than looking for evidence for the MWI inside the formalism of quantum mechanics, one should do a meta analysis by asking why, out of all the currently accepted physical theories, QM should be the only theory, apart from Newtonian mechanics, which we know is wrong outside of a narrow range of mass-energies, that does NOT predict a multiverse?

Stuart LaForge

 

On Wed, Jul 30, 2025 at 12:45 PM John Clark <johnk...@gmail.com> wrote:

In today's issue of the journal Nature is a report of a survey of physicists that Nature conducted about the meaning of Quantum Mechanics, it's interesting that even after a century there is not something even close to a consensus. Even two physicists who won a Nobel prize for performing an experiment that explores the qualities of quantum reality disagree with each other over what their experiment is trying to tell us.  Another physicist says "The implication [of the survey] is that many quantum researchers simply use quantum theory without engaging deeply with what it means — the ‘shut up and calculate’ approach."

Physicists disagree wildly on what quantum mechanics says about reality

John K Clark    See what's on my new list at  Extropolis

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[John Clark]

On Thu, Aug 7, 2025 at 4:49 PM Lawrence Crowell <goldenfield...@gmail.com> wrote:

>> Nobody is being dragged to the one true path, instead there is an astronomical, possibly infinite, number of paths that are all equally real and a real observer to observe everyone of them.   

> This all begins to sound the same as Bohm's active vs inactive channels.

There are similarities. David Deutsch said Bohm's Pilot Wave theory is just Everett's Many Worlds in denial, you have just as many branches of the wave function as Everett does, the only differences in addition to Schrödinger's Equation Bohm adds extraneous mathematical machinery that does nothing but point to one of those branches and say "this is the real one". This additional mathematics does not improve on the ability to make predictions at all, in fact nobody has yet found a way to make it compatible with special relativity. That's why Many Worlds is bare-bones no-nonsense quantum mechanics, it has no extraneous bells and whistles.

> The observer is in a sense frame dragged along a path in Hilbert or Fubini-Study space corresponding to a certain outcome. Somehow, by the magic of consciousness or something, the observer only experiences one path. This really is not that different from collapse.

But if Many Worlds is correct then there's no such thing as "THE observer", there is only "AN observer", one for every path that is not forbidden by the laws of physics. And I don't claim that Many Worlds is definitely correct, I only claim that, at least so far, it is the least bad quantum interpretation. And if it's not true then reality must be some bizarre thing even stranger than Many Worlds. 

 

>>> You can invoke collapse or MWI splitting, but in both cases this is just an ancillary assumption.

>> Schrodinger's equation says nothing about the wave collapsing so if you want to have that you've got to tack on an additional assumption, but that's not the case for splitting, that comes about naturally. An electron can have many different positions and have many different velocities but the equation does not say that one particular position or one particular velocity is more real than the others, and I know what "real" is supposed to mean from everyday experience therefore, assuming only that Schrodinger's equation is correct, the only way those two facts can be reconciled is if there is a John Clark observing that electron having every position and velocity that is not forbidden by the laws of physics. The only assumption Many Worlds makes is that Schrodinger's Equation means what it says.

 

> All that Schrodinger's equation tells you is there is an evolution of superposed amplitudes that correspond by modulus square to a probability.

If you want to get a probability out of a quantum wave then modulus square is the only way to do it, and the only reason physicists think a quantum wave is interesting and is worth studying is because the probability it produces corresponds with experimental results. 

 

> It does not tell you which outcome happens.

Actually it does, it tells you that an astronomical, possibly an infinite, number of outcomes happen, and Lawrence Crowell is in every one of them. The only question Schrodinger's equation can't answer is, are you the Lawrence Crowell that is in the world (or worlds) where the cat is alive, or are you the Lawrence Crowell that is in the world where the cat is dead? You can't obtain that information by making a calculation, the only way to answer that question is by making an observation.

> To ask why an outcome occurs, or how it is that a measurement is what it is, is to ask an irrelevant question. This is a metaphysical issue and not something appropriate to physics.

Depending on particulars, a "why" question might be inappropriate for physics, but a "how" question never is. 

>>>> If Many worlds is correct then any change, no matter how small, causes the universe to split, but the vast majority of those changes have a negligible effect on the conscious experience of a scientist doing a quantum mechanical experiment to investigate the nature of reality. The only difference between two universes might be that in one a micrometeorite smaller than a bacteria hits the planet Pluto, but in the other it does not; Pluto is very slightly different but the conscious experience of the scientist in both universes is identical.

 

>>> You are using a coarse grain argument to brush over the problem. By doing that you are breaking the unitarity of QM, even if slightly.

>> But I'm lumping universes together such that, although they're all slightly different, the conscious state of the experimenter is exactly identical in all of them, therefore if it does violate unitarity then that violation is so small as to be completely unobservable even in theory, much less in practice. 

> I generally do not bring consciousness into physics problems and theory. 

In a way you sort of have to because experimental results are of vital importance in the study of physics. and that involves a conscious observation. 

 

> Given n measurements of a 2-state system, there are 2^n possible sets of outcomes. This Markov branching set of possibilities means the local operators in classical computation (LOCC), sometimes called Stochastic LOCC or SLOCC, computes this as an outcome. Prior to a measurement there is no actual computation, contrary to what we often naively think with quantum computers, or computation output and so this problem is in effect removed as a "logarithm" of this with a set of n configurations.We might consider measurements as an entanglement and all this would entail in a purely quantum setting in an n-tanglement. Yet with or without MWI outcomes are LOCC, and within MWI there is effectively a computation output according to an observer. For the universe at large with n → ∞, there is an implicit power set realization. By Chaitin's incomputable halting probability this is undecidable by Godel's first theorem. 

Perhaps that's why you can't calculate if you're in a dead cat world or in a live cat world, to make that determination you've got to open the box and look at the cat. 

John K Clark 

[Lawrence Crowell]

On Thu, Aug 7, 2025 at 11:52 PM Stuart LaForge <stuart....@gmail.com> wrote:

On Wed, Aug 6, 2025 at 2:34 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

This survey illustrates that the Copenhagen interpretation is most popular. I have sympathies with that as well, though I am not devoted to it. Niels Bohr advanced the idea that there is a correspondence between classical observables and quantum observables and their outcomes. This is a dualist world perspective, which some people dislike because it rankles with the idea that all is quantum. However, string theory has quantum gravitation on a classical background, while loop quantum gravitation has a putative all quantum spin-net approach that so far appears unworkable. I tend towards the more ψ-epistemic interpretations but have some interest in the many worlds interpretation that is ψ-ontological.

 

My problem with an epistemic wavefunction is that it makes quantum mechanics weirder and spookier than it needs to be. If the wavefunction is just some mathematical tool that allows people to predict probability distributions that particle states are drawn from, then that necessarily entails some mysterious physical mechanism, including memory and information processing, by which particle states are coordinated and constrained to follow those probabilities. When any given quantum state is measured for a particle, that particular state has to somehow "know" about the probabilities of all the other possible, but counterfactual, particle states that were not measured. It is like the measured state is entangled with all the counterfactual states, but how is that possible if the counterfactual states are merely imaginary figments of an epistemic wavefunction that only exists in your head? It would mean that particles would have to be able to access the epistemic wavefunction in your head and that would imply that particles have telepathy and are able to do abstract math which seems to me at best like panpsychism, and at worse like superdeterminism in the sense the entire universe is acting like Descartes's Evil Demon and trying to con you into believing that you have such a thing as a choice that was not predestined since the moment of the big bang.

Let me give a classical example to illustrate what I mean. When you roll a normal six-sided die, the probability that you roll a 6 is 1/6. The physical mechanism by which the 6 knows how often to come up is that the die is ontological and has six faces of equal area, so the frequency of observation of 6s is physically constrained by the geometric fact that the counterfactual faces 1-5 exist and shape the probability distribution even when they are not the number that gets rolled. Now imagine how weird it would be if you had an epistemic die where one and only one face somehow came into existence the moment you rolled it. And yes, a simulated die running on your phone could do that, but we are using dice as a model of what are supposed to be the wave functions of  actual ontologically existent particles. Epistemic wave functions are parsimonious so they act like simulations under tight resource constraints of computability. The moon is a mathematical abstraction that does not waste resources becoming real until you happen to look at it, just like a video game.

On the other hand, if you accept the extravagance of the infinity that an ontological wave function affords, then when your favorite electron is spin up in this universe, then its wave function is in phase with the you that measures it be up and out of phase with the you that measures it to be spin down.

I do not think that quantum mechanics has any axiomatic decision or derivable way to determine whether QM is epistemic or ontological. This is a part of my insistence that quantum interpretations are what in set theory we might call "forcings" of a set theory into a more general set theory with new conditions. Whether these ancillary axioms are true or false has no bearing on the truth of the bare set theory, which in this case is quantum mechanics. 

We are arguing primarily here over MWI, where I have outlined what I see as serious difficulties with it. If we were arguing over QuBism, almost the antithesis of MWI as almost the ultimate epistemic interpretation. I would be similarly calling out problems with that. Curiously, this has difficulties with uncomputability and Godelian incompleteness. It leads to a sort of self-referential solipsism. This discussion has centered around MWI, which is why most of my arguments have been there. That this involves uncomputability is a part of my argument that physics has unobservable aspects, where if we consider quantum states as computations or information that is processed, then there is domain of undecidable propositions. 

If there were a switch that turned on at time = 0, off at time = 1 unit, back on at time = 1/2 unit, then off at 1/4 unit of time in this Zeno process we might ask what would happen at time = 2 units. Is the switch on or off? Well, that switch is going to asymptotically approach infinite speed and energy required to do this. Ignoring the practical problem of holding this switch together, the mass-energy of this switch will become a black hole before time = 2 units is reached. This leads to problems with the Malement-Hogarth spacetimes that are able to serve as hyper-Turing machines. However, this all can only occur in a region concealed by an event horizon or in a black hole. The mass-inflation singularity of the Kerr-Newman black hole is a MH hyper-Turing machine of this sort. However, we cannot observe this from the exterior position. Hidden variables have this feature as well, where for quantum mechanics to be consistent these are nonlocal without any signalling or causal influence. We might within the construct of quantum geometry consider this to be a sort of quantum black hole. In fact in quantum geometry there are emergent light-cone-like conditions. The causal incompleteness of black holes and quantum physics are then categorically equivalents under a functor condition.

There is then another domain that is less evident and that is cosmology. Quantum cosmology is a very different domain.

 

It has been my thinking the apparat quantum interpretations are auxiliary postulates or physical axioms that are imposed on quantum mechanics. I think a good interpretation is one that is not derivable from basic quantum physical postulates and is then only falsifiable with quantum theory. Such quantum interpretations are then unobservable or undecidable based on both experimental outcomes and formal derivations with quantum theory. This means quantum interpretations are at best only useful with preferably a minimal amount of excess baggage. They may serve as explanatory heuristics for certain problems or in certain presentations.

My research into the hypothesis I discussed earlier that the Hubble tension might be caused by a double rotation of the Hubble sphere in 4-D Euclidean space, the SO(4) group, resulted in some very interesting insights. I have concluded that even classical physics in the form of special and general relativity both predict multiverses in distinct ways. That means that the only extant physical theory that does not directly or indirectly imply or predict a multiverse, at least in some "interpretation", is Newtonian mechanics. Take the following examples:

The Hubble tension appears to have been solved. This appears to be solved, see here https://arxiv.org/abs/2501.17934v1 , by considering the fact that the local group of galaxies is in a relative cosmic void, which allows for the local Hubble parameter to be larger. 

LC

 

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[John Clark]

On Fri, Aug 8, 2025 at 10:39 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> If there were a switch that turned on at time = 0, off at time = 1 unit, back on at time = 1/2 unit, then off at 1/4 unit of time in this Zeno process we might ask what would happen at time = 2 units. Is the switch on or off? Well, that switch is going to asymptotically approach infinite speed and energy required to do this. Ignoring the practical problem of holding this switch together, the mass-energy of this switch will become a black hole before time = 2 units is reached.

That would only be a problem if time is continuous, but not if time is composed of a finite number of chunks, and nobody knows if it is or isn't. It's food for thought that although pure mathematics has discovered many things that are infinite, science has never discovered an infinite number of anything.  

John K Clark

[Lawrence Crowell]

Space and time may be continuous, at least on the IR. The Planck scale is just a scale limit to localizing a qubit, not that space or time are segmented into finite elements.

LC

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[Will Steinberg]

I definitely have the feeling that there is no smallest or largest possible length, Wolfram be damned.  It just doesn’t make sense to me personally.  

Speaking of scale, I get tired of people saying how small we are compared to the universe.  Even comparing our largest and smallest finite distances, we’re right about in the middle.

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[Lawrence Crowell]

On Mon, Aug 11, 2025 at 9:30 AM Will Steinberg <steinbe...@gmail.com> wrote:

I definitely have the feeling that there is no smallest or largest possible length, Wolfram be damned.  It just doesn’t make sense to me personally.  

Speaking of scale, I get tired of people saying how small we are compared to the universe.  Even comparing our largest and smallest finite distances, we’re right about in the middle.

If you try to measure space with extremely high energy approaching the Planck scale various quantum exciton physics prevents one from measuring at smaller scales. Those excitons are quantum black holes with a small number of Planck masses. Quantum gravitation physics prevents closer measurements and if you slam particles together at higher energy you just get bigger black holes, which in a T-duality sense corresponds to larger mass-energy at a larger scale. At the low energy scale the simultaneous arrival time of photons from billion light year distant high energy events means there is no dispersion that a cut-off in the scale of spacetime would imply. In fact space appears smooth down to .01 Planck lengths.

LC

 

On Sun, Aug 10, 2025 at 8:18 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

Space and time may be continuous, at least on the IR. The Planck scale is just a scale limit to localizing a qubit, not that space or time are segmented into finite elements.

LC

On Sun, Aug 10, 2025, 5:17 AM John Clark <johnk...@gmail.com> wrote:

On Fri, Aug 8, 2025 at 10:39 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> If there were a switch that turned on at time = 0, off at time = 1 unit, back on at time = 1/2 unit, then off at 1/4 unit of time in this Zeno process we might ask what would happen at time = 2 units. Is the switch on or off? Well, that switch is going to asymptotically approach infinite speed and energy required to do this. Ignoring the practical problem of holding this switch together, the mass-energy of this switch will become a black hole before time = 2 units is reached.

That would only be a problem if time is continuous, but not if time is composed of a finite number of chunks, and nobody knows if it is or isn't. It's food for thought that although pure mathematics has discovered many things that are infinite, science has never discovered an infinite number of anything.  

John K Clark

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[Will Steinberg]

I agree thag no cutoff makes sense, though I would caution against declaring what’s happening so confidently (“these excitons are…”) versus “in my reckoning, these excitons are…” or some such.  There may be a lot of unknowns in physics but one real constant so far is that everybody, eventually, ends up being wrong.

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[Lawrence Crowell]

On Mon, Aug 11, 2025 at 11:44 AM Will Steinberg <steinbe...@gmail.com> wrote:

I agree thag no cutoff makes sense, though I would caution against declaring what’s happening so confidently (“these excitons are…”) versus “in my reckoning, these excitons are…” or some such.  There may be a lot of unknowns in physics but one real constant so far is that everybody, eventually, ends up being wrong.

The Planck mass is m_p = √(ħc/G) and the Planck length is ℓ_p = √(Għ/c^3). If you probe space at the Planck scale you produce a unit of Planck mass. This is a black hole and it conceals a tiny region you cannot causally interact with or observe. If you apply more energy you create a quantum black hole with N such Planck masses and a larger radius and horizon area. As you probe into smaller regions with higher energy you reach a point where your greater energy is confined in a larger region. This is an aspect of T-duality, where the momentum that scales as p ~ 1/r is equivalent to a scaling that is r or where 1/r ~ α'r. This is a reduced form of the linear fractional transformation that defines modular forms and symmetries.

LC

 

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[John Clark]

On Mon, Aug 11, 2025 at 11:42 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> In fact space appears smooth down to .01 Planck lengths.

If it turns out that both space and time are continuous wouldn't that mean that developing a quantum theory of gravity is impossible because gravity is not a quantum force? And wouldn't that mean that before a wavelength of light reaches the Planck scale some new currently unknown property of quantum mechanics kicks in and prevents that super energetic super small photon from turning into a black hole?  

John K Clark

[Lawrence Crowell]

It means the sort of quantum gravity promoted by loop quantum gravitation is wrong.

LC

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[John Clark]

On Mon, Aug 11, 2025 at 10:30 AM Will Steinberg <steinbe...@gmail.com> wrote:

> I definitely have the feeling that there is no smallest or largest possible length,

If light had a wavelength that was longer than the diameter of the observable universe then how could we detect it? 

> Speaking of scale, I get tired of people saying how small we are compared to the universe.  Even comparing our largest and smallest finite distances, we’re right about in the middle.

I agree. I also get tired of that old cliché "we live in an average part of the universe". We don't. An average part of the universe only contains one atom per cubic meter. And it's true that the Earth is much much smaller than the sun, but it's also much much more complex, in fact it's by far the most complex object in the known universe. 

 

The Copernican Principle, asserts that Earth is not in a special or privileged location in the universe and some people give it the same respect they give the second law of thermodynamics, but I don't because it's not a law of nature at all, it's just an aphorism with no more cosmic significance than "The early bird catches the worm."

John K Clark

[John Clark]

On Mon, Aug 11, 2025 at 7:52 PM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> It means the sort of quantum gravity promoted by loop quantum gravitation is wrong.

If space and time are continuous I don't understand how ANY quantum theory of gravity could be right.  

John K Clark

[Lawrence Crowell]

In standard quantum mechanics the wave functions are smooth, in fact C^\inty, and observables are differentiable. The Planck scale is not about space, time or spacetime being sliced up into pieces. It defines the smallest area that can contain a quantum bit or qubit.

LC

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[Stuart LaForge]

Gravitational waves do not obey the Planck relation. If gravity is quantized, then it would seem to be at much larger scales than the Planck length. I mean black holes seem very particle-like in that they only have three properties of mass, charge, and spin. I mean since a black hole is a bound system, those properties should correlate with very large integer-valued quantum numbers. Maybe entire Everett branches are the quanta of gravity.

Stuart LaForge

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[Stuart LaForge]

So if space-time is continuous, then why do think that space-time had a beginning? If the cosmic scale factor 

needs to be multiplied by a reference distance, then how could you go from zero space to some space? What does it even mean to have zero space whether its empty or full? What if time is endlessly asymptotic on both ends due to infinite curvature?

Why would we think that the time t lies on a closed interval? How do we know that t, and therefore a(t), does not lie on (0, infinity) instead of [0, infinity)?

An argument could be made against the existence of singularities in the Schwarzschild metric based on similar logic. Maybe there is no beginning or end to space-time because of length contraction, time dilation, and Zeno's paradox.

I am questioning what seems like an unspoken axiom that there was a t=0 instead of a universe that has been expanding and will expand forever.

Stuart LaForge

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[John Clark]

On Wed, Aug 13, 2025 at 1:03 AM Stuart LaForge <stuart....@gmail.com> wrote:

> Gravitational waves do not obey the Planck relation. If gravity is quantized, then it would seem to be at much larger scales than the Planck length. I mean black holes seem very particle-like in that they only have three properties of mass, charge, and spin.

Black Holes look that way when we observe them from several thousand light years away, but if we got close up and personal with one of them we might find that they have hair after all. Some people think that might solve a problem that Black Holes have with the second law of thermodynamics. If I throw a high entropy object into a Black Hole and then, after several trillion years, the Black Hole evaporates due to Hawking radiation, was that entropy destroyed in violation of the second law of thermodynamics? Maybe not. Maybe if we looked very closely we'd find that 3 numbers are not enough to describe a Black Hole and Hawking radiation is not pure blackbody radiation as was previously thought but also contains information about that high entropy object.  

John K Clark

[John Clark]

On Tue, Aug 12, 2025 at 1:20 PM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> In standard quantum mechanics the wave functions are smooth, in fact C^\inty, and observables are differentiable.

That's what quantum mechanics says and all our observations are consistent with that, but all our observations are made at scales much much larger than the Planck scale. So is quantum mechanics right about that? If gravity can be quantized (and I don't pretend to know if it can be or not) then I don't see how quantum mechanics could be right about space and time being continuous.

 

> The Planck scale is not about space, time or spacetime being sliced up into pieces. It defines the smallest area that can contain a quantum bit or qubit.

If an area is too small to contain a qubit then I don't see how it would be possible, even in theory, to tell the difference between one such tiny area and another. And I don't see how such a tiny area could have any effect on quantum mechanics or on General Relativity. And so I don't see in what sense you could say that such tiny areas exist. 

John K Clark 

[Lawrence Crowell]

A quantum form of a gravitational wave is a graviton, and it can occur with  wavelengths far larger than the Planck scale.

LC

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[Lawrence Crowell]

The origin of a deSitter spatial surface is as an instanton, which is quantum mechanical.

LC

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[Lawrence Crowell]

I published a paper on this and how this results in gravitons. This would have a signature in gravitational radiation. https://arxiv.org/abs/2007.01106

LC

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[Stuart LaForge]

Yes, I remember coming across your paper when I was researching my double rotation of the universe as a supertranslation from the BMS-symmetry group in the asymptotically flat space-time at extremely large scales. Of course the idea that the locally measured Hubble parameter should be bigger than the CMB H because we are in a void does strike me as the simpler explanation. Plus it agrees with my earlier observations that Friedmann's critical density applies locally as well as cosmologically. Local mass densities even a little larger than the critical density should contract while local densities lower than the critical density should collapse. In this way, small overdensities should contract evolving into filaments and membranes, while small underdensities should expand eventually evolving into voids.

BTW, I asked GPT5 to explain how instatons relate to De Sitter space and its answer was very clear and succinct at less than a page. It even drew me this nifty graph:

Needless to say I was impressed with GPT5. I am still thinking about instantons though, and I can't help but think that the equatorial point at t=0 is acting like some kind of event horizon where time and space are switching roles. In my mind imaginary time is space and imaginary space is time just as imaginary circles are hyperbolas and imaginary hyperbolas are circles.

Stuart LaForge

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[Lawrence Crowell]

It is the de Sitter hyperboloid, clipped at the middle that is replaced with a cap that has a Euclidean signature. This is seen on the right of the image below. The de Sitter spacetime is seen on the left, and the flat spatial verse has the patch marked by the green p =  ±∞ lines and then the Euclidean patch is the rest of the hyperboloid turned into a strip.

LC

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