A Private View of Quantum Reality

Quantum theorist Christopher Fuchs explains how to solve the paradoxes of quantum mechanics. His price: physics gets personal.

Katherine Taylor for Quanta Magazine

Christopher Fuchs is the developer and main proponent of QBism, an alternative interpretation of quantum mechanics that treats the quantum wave function as a reflection of ignorance.

Christopher Fuchs describes physics as “a dynamic interplay between storytelling and equation writing. Neither one stands alone, not even at the end of the day.” And indeed Fuchs, a physicist at the University of Massachusetts, Boston, has a radical story to tell. The story is called QBism, and it goes something like this.

Once upon a time there was a wave function, which was said to completely describe the state of a physical system out in the world. The shape of the wave function encodes the probabilities for the outcomes of any measurements an observer might perform on it, but the wave function belonged to nature itself, an objective description of an objective reality.

Then Fuchs came along. Along with the researchers Carlton Caves and Rüdiger Schack, he interpreted the wave function’s probabilities as Bayesian probabilities — that is, as subjective degrees of belief about the system. Bayesian probabilities could be thought of as gambling attitudes for placing bets on measurement outcomes, attitudes that are updated as new data come to light. In other words, Fuchs argued, the wave function does not describe the world — it describes the observer. “Quantum mechanics,” he says, “is a law of thought.”

Quantum Bayesianism, or QBism as Fuchs now calls it, solves many of quantum theory’s deepest mysteries. Take, for instance, the infamous “collapse of the wave function,” wherein the quantum system inexplicably transitions from multiple simultaneous states to a single actuality. According to QBism, the wave function’s “collapse” is simply the observer updating his or her beliefs after making a measurement. Spooky action at a distance, wherein one observer’s measurement of a particle right here collapses the wave function of a particle way over there, turns out not to be so spooky — the measurement here simply provides information that the observer can use to bet on the state of the distant particle, should she come into contact with it. But how, we might ask, does her measurement here affect the outcome of a measurement a second observer will make over there? In fact, it doesn’t. Since the wavefunction doesn’t belong to the system itself, each observer has her own. My wavefunction doesn’t have to align with yours.

Olena Shmahalo/Quanta Magazine

A quantum particle can be in a range of possible states. When an observer makes a measurement, she instantaneously “collapses” the wave function into one possible state. QBism argues that this collapse isn’t mysterious. It just reflects the updated knowledge of the observer. She didn’t know where the particle was before the measurement. Now she does.

In a sea of interpretations of quantum weirdness, QBism swims alone. The traditional “Copenhagen interpretation” treats the observer as somehow standing outside of nature, imbued with mysterious wave-function-collapsing powers, governed by laws of physics that are different from those that govern what’s being observed. That’s all well and good until a second observer comes along to observe the first observer. The “many worlds” interpretation claims that the universe and all of its observers are described by a single, giant wave function that never collapses. Of course, to make that work, one must insist that at every fork in the road — every coin toss, every decision, every moment — the wave function branches and so do we, splitting into countless versions of ourselves who have collectively done and not done everything we’ll ever do or not do. For those to whom a set of infinite parallel realities is too high a price to pay to avoid wave-function collapse, there’s always the Bohmian interpretation, which seeks to restore a more concrete reality to the world by postulating the existence of a guiding force that permeates the universe and deterministically governs everything in it. Unfortunately, this new reality lies forever out of reach of scientific probing.

Those interpretations all have something in common: They treat the wave function as a description of an objective reality shared by multiple observers. QBism, on the other hand, treats the wave function as a description of a single observer’s subjective knowledge. It resolves all of the quantum paradoxes, but at the not insignificant cost of anything we might call “reality.” Then again, maybe that’s what quantum mechanics has been trying to tell us all along — that a single objective reality is an illusion.

QBism also raises a host of new and equally mysterious questions. If the wave function describes an observer, does the observer have to be human? Does that observer have to have consciousness? Could it be a dog? (“Dogs don’t use wave functions,” Fuchs said. “Heck, I didn’t collapse a wave function until I was 34.”) If my wave function doesn’t have to align with yours, do we live in the same universe? And if quantum mechanics doesn’t describe an external reality, what does?

Fuchs struggles with these questions, often working through his thoughts in the form of emails. His missives have become legendary. For two decades Fuchs has compiled them into huge documents — he calls them his samizdats — which have made the rounds among quantum physicists and philosophers as a kind of underground manuscript. After Fuchs lost his Los Alamos home to a fire in May 2000, he decided to back them up by posting them on the scientific preprint site arxiv.org as a massive paper, which was later published by Cambridge University Press as a 500-page book. A second samizdat was released 13 years later with an additional 2,300 pages. The emails reveal both Fuchs’ searching mind and his colorful character. As the physicist David Mermin puts it, “If Chris Fuchs did not exist then God would have been remiss in not inventing him.”

So how will the QBism story end? Ultimately, Fuchs wants to answer a single question, one famously asked by the eminent physicist John Archibald Wheeler, who was Fuchs’ mentor: Why the quantum? That is, why should the world be built in such a way that it can only be described by the strange rules of quantum mechanics?

In the meantime, Quanta caught up with Fuchs at a coffee shop in Cambridge, Massachusetts, to ask him some questions of our own. An edited and condensed version of our conversation follows.

QUANTA MAGAZINE: You’ve said, “I knew I had to become a physicist, not for the love of physics, but for the distrust of it.”

CHRISTOPHER FUCHS: I was a big science fiction fan when I was a kid. I grew up in a small town in Texas and I really enjoyed the idea of space flight. It seemed inevitable — we were going to the moon, that was just the first step, science is limitless and eventually we’d be doing the things they do in Star Trek: go to planets, find new creatures, have adventures. So I started reading books about physics and space travel, and it was there that I first learned that space travel would be difficult because of the great distances between stars. How do you get around this? I learned about John Wheeler and black holes and wormholes, and that possibly wormholes could be a way to get around the speed-limit problem, or we could get past the speed limit using exotic particles called tachyons. I ate the stuff up. Most of it turned out to be pretty improbable; wormholes had proven to be unstable and nobody really believed in tachyons. Overall, the message to me was that physics wouldn’t allow us to get to the stars. As a bit of a joke, I would tell my friends, if the laws of physics won’t allow us to go to the stars, the laws of physics must be wrong!

Probability does not exist! It will go the way of phlogiston, witches, elves and fairies.

You ended up studying with John Wheeler.

The first time I went to the University of Texas, it dawned on me that the guy I’d read about years before, John Wheeler, was actually a professor there. So I went and read some of his newer papers, in which he was talking about “law without law.” He’d say things like, “In the end, the only law is that there is no law.” There’s no ultimate law of physics. All the laws of physics are mutable and that mutability itself is a principle of physics. He’d say, there’s no law of physics that hasn’t been transcended. I saw this, and I remembered my joke about how the laws of physics must be wrong, and I was immensely attracted to this idea that maybe ultimately there actually are no laws of physics. What there is in place of laws, I didn’t know. But if the laws weren’t 100 percent trustworthy, maybe there was a back door to the stars. It was all youthful romanticism; I hadn’t even had a physics course yet.

In one of your papers, you mention that Erwin Schrödinger wrote about the Greek influence on our concept of reality, and that it’s a historical contingency that we speak about reality without including the subject — the person doing the speaking. Are you trying to break the spell of Greek thinking?

Schrödinger thought that the Greeks had a kind of hold over us — they saw that the only way to make progress in thinking about the world was to talk about it without the “knowing subject” in it. QBism goes against that strain by saying that quantum mechanics is not about how the world is without us; instead it’s precisely about us in the world. The subject matter of the theory is not the world or us but us-within-the-world, the interface between the two.

It’s so ingrained in us to think about the world without thinking of ourselves in it. It reminds me of Einstein questioning space and time — these features of the world that seemed so absolute that no one even thought to question them.

It’s said that in earlier civilizations, people didn’t quite know how to distinguish between objective and subjective. But once the idea of separating the two gained a toehold, we were told that we have to do this, and that science is about the objective. And now that it’s done, it’s hard to turn back. I think the biggest fear people have of QBism is precisely this: that it’s anthropocentric. The feeling is, we got over that with Copernicus, and this has got to be a step backwards. But I think if we really want a universe that’s rife with possibility with no ultimate limits on it, this is exactly where you’ve got to go.

How does QBism get you around those limits?

One way to look at it is that the laws of physics aren’t about the stuff “out there.” Rather, they are our best expressions, our most inclusive statements, of what our own limitations are. When we say the speed of light is the ultimate speed limit, we’re saying that we can’t go beyond the speed of light. But just as our brains have gotten bigger through Darwinian evolution, one can imagine that eventually we’ll have evolved to a stage where we can take advantage of things that we can’t now. We might call those things “changes in the laws of physics.” Usually we think of the universe as this rigid thing that can’t be changed. Instead, methodologically we should assume just the opposite: that the universe is before us so that we can shape it, that it can be changed, and that it will push back on us. We’ll understand our limits by noticing how much it pushes back on us.

Let’s talk about probability.

Probability does not exist! Bruno de Finetti, in the intro to his two-volume set on probability theory, writes in all-capital letters, “PROBABILITY DOES NOT EXIST.” He says it will go the way of phlogiston, witches, elves and fairies.

When the founders of quantum mechanics realized that the theory describes the world in terms of probabilities, they took that to mean that the world itself is probabilistic.

In Pierre-Simon Laplace’s day, probability was thought of as a subjective statement — you don’t know everything, but you can manage by quantifying your knowledge. But sometime in the late 1800s and early 1900s, probabilities started cropping up in ways that appeared objective. People were using statistical methods to derive things that could be measured in the laboratory — things like heat. So people figured, if this quantity arises because of probabilistic considerations, and it’s objective, it must be that the probabilities are objective as well. Then quantum mechanics came along. The Copenhagen crowd was arguing that quantum mechanics is a complete theory, finished, closed, which was often taken to mean that all of its features should be objective features of nature. If quantum states give probabilities, those probabilities should also be objective features of nature. On the other side of the fence was Albert Einstein, who said quantum mechanics is not complete. When he described probabilities in quantum mechanics, he seemed to interpret them as statements of incomplete knowledge, subjective states.

So when you say that probability doesn’t exist, you mean that objective probability doesn’t exist.

Right, it doesn’t exist as something out in the world without a gambling agent. But suppose you’ve convinced yourself that the right way to understand probability is as a description of uncertainty and ignorance. Now there’s a spectrum of positions you could take. According to the Bayesian statistician I.J. Good, there are 46,656 varieties. When we started working on quantum Bayesianism, we tried to take a stance on probability that was like E.T. Jaynes’ stance: We’ll admit that probabilities are in our heads — my probabilities are in my head, your probabilities are in your head — but if I base my probabilities on the same information that you base yours on, our two probability assignments should be the same. Conditioned on the information, they should be objective. In the spectrum of 46,656 varieties, this stance is called “objective Bayesianism.”

At the other end of the spectrum is Bruno de Finetti. He says there’s no reason whatsoever for my probabilities and yours to match, because mine are based on my experience and yours are based on your experience. The best we can do, in that case, if we think of probabilities as gambling attitudes, is try to make all of our personal gambling attitudes internally consistent. I should do that with mine, and you with yours, but that’s the best we can do. That’s what de Finetti meant when he said probability does not exist. He meant, let’s take the extreme stance. Instead of saying probabilities are mostly in my head but there are some extra rules that still anchor them to the world, he got rid of the anchor.

Eventually my colleague Rüdiger Schack and I felt that to be consistent we had to break the ties with Jaynes and move more in the direction of de Finetti. Where Jaynes made fun of de Finetti, we thought, actually, that’s where the real solution lies.

Is that when the name changed from quantum Bayesianism to QBism?

Quantum Bayesianism was too much of a mouthful, so I started calling it QBism. As soon as I started calling it QBism, people paid more attention to it! But my colleague David Mermin started complaining that QBism really shouldn’t be short for quantum Bayesianism because there are a lot of Bayesians out there who wouldn’t accept our conclusions. So he wanted to call it quantum Brunoism, for Bruno de Finetti. The trouble with that is that there are parts of the metaphysics of QBism that even de Finetti wouldn’t accept!

But then I found the perfect B. The trouble is, it’s so ugly you wouldn’t want to show it off in public. It’s a term that comes from Supreme Court Justice Oliver Wendell Holmes Jr. He described his own philosophy as “bettabilitarianism.” It’s the philosophy that, as Louis Menand said, “the world is loose at the joints.” The best you can do is gamble on the consequences of your actions. [The portmanteau comes from bet and ability.] I think this fits it perfectly, but I don’t want to say that QBism stands for quantum bettabilitarianism, so I think it’s best to do what KFC did. It used to be Kentucky Fried Chicken; now it’s just KFC.

If quantum mechanics is a user’s manual, as you’ve called it, who’s the user? Einstein talked about observers, but an observer in quantum mechanics is different from an observer in relativity.

The other day I was talking to the philosopher Rob DiSalle. He said that the observer is not so problematic in relativity because one observer can, so to speak, “look over the shoulder of another observer.” I like that phrasing. In other words, you can take what one observer sees and use transformation laws to see what the other observer will see. Bohr really played that up. He played up the similarities between quantum mechanics and relativity, and he couldn’t understand why Einstein wouldn’t accept quantum theory. But I think the problems are different. As QBism understands a quantum measurement outcome, it’s personal. No one else can see it. I see it or you see it. There’s no transformation that takes the one personal experience to the other personal experience. William James was just wrong when he tried to argue that “two minds can know one thing.”

Does that mean that, as Arthur Eddington put it, the stuff of the world is mind stuff?

QBism would say, it’s not that the world is built up from stuff on “the outside” as the Greeks would have had it. Nor is it built up from stuff on “the inside” as the idealists, like George Berkeley and Eddington, would have it. Rather, the stuff of the world is in the character of what each of us encounters every living moment — stuff that is neither inside nor outside, but prior to the very notion of a cut between the two at all.

So eventually objectivity comes in?

I hope it does. Ultimately I view QBism as a quest to point to something in the world and say, that’s intrinsic to the world. But I don’t have a conclusive answer yet. Quantum mechanics is a single-user theory, but by dissecting it, you can learn something about the world that all of us are immersed in.

Treating quantum mechanics as a single-user theory resolves a lot of the paradoxes, like spooky action at a distance.

Yes, but in a way that a lot of people find troubling. The usual story of Bell’s theorem is that it tells us the world must be nonlocal. That there really is spooky action at a distance. So they solved one mystery by adding a pretty damn big mystery! What is this nonlocality? Give me a full theory of it. My fellow QBists and I instead think that what Bell’s theorem really indicates is that the outcomes of measurements are experiences, not revelations of something that’s already there. Of course others think that we gave up on science as a discipline, because we talk about subjective degrees of belief. But we think it solves all of the foundational conundrums. The only thing it doesn’t solve is Wheeler’s question, why the quantum?

Why the quantum?

I wish I had more of a sense. I’ve become fascinated by these beautiful mathematical structures called SICs, symmetric informationally complete measurements — horrible name, almost as bad as bettabilitarianism. They can be used to rewrite the Born rule [the mathematical procedure that generates probabilities in quantum mechanics] in a different language, in which it appears that the Born rule is somehow deeply about analyzing the real in terms of hypotheticals. If you have it in your heart — and not everyone does — that the real message of quantum mechanics is that the world is loose at the joints, that there really is contingency in the world, that there really can be novelty in the world, then the world is about possibilities all the time, and quantum mechanics ties them together. It might take us 25 years to get the mathematics right, but in 25 years let’s have this conversation again!

This article was reprinted on Wired.com.

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  • The subhead—“His price: reality becomes an illusion”—is just wrong. It’s even contradicted by the article itself. “His price: physics must deal with personal experiences” would be better, and not much longer at that.

  • Or, for a snappier statement, “His price: physics must get personal.” Simple, viable, and having the same word count as the original.

    If reality WERE an illusion, editing 2,349 pages of QBist samizdat would have been a lot easier.

    The person who edited 2,349 pages of QBist samizdat

  • There is an objective reality; it’s on a server somewhere. We each have our own copy to hack as we want. Why the quantum? Because pixels.

  • To me, QBism is no more troubling than MWI. Example: Although I have never observed or interacted with you and don’t even know that you exist, MWI suggests that everytime you make a choice you create an infinite number of universes where every possible outcome (however remote) is realized, and there’s always an outcome where I’m dead. I really don’t care for folks who don’t even exist to me according to Copenhagen having so great an influence over my destiny. And even less thanks that some hypothetical consciousness located a hundred billion light years away, whose spacetime light cone cannot intersect mine, can still collapse a wave functionthat will snuff me out.

  • Thanks, Blake, that feels a little more on the money, but then again that’s my personal experience of your comment and the article. Less facetiously, while each experience of say, the collapsed wave is highly personal and circumstantial, isn’t true that what I, as an avowed ignoramus, don’t know about physics is the same as what anyone doesn’t know? Most people don’t know anything about the quantum (mathematically speaking). The ignorance is not personal, it’s collective.

  • Thank you all for your thoughtful comments. Upon further consideration Blake Stacey is exactly right about the subtitle—we have changed it at your suggestion. Thank you for your input!

  • Science writing that’s clear, comprehensive, and concise. Thank you, Amanda Gefter, for asking the very questions that come to mind when trespassing into this thorny thicket.

  • I’ve spent my life reading the books of all these physicists and have concluded that they just *do not know* what’s going on. But I will continue.

  • It sounds like QBism has a lot in common with the “philosophy of organism” — now “process philosophy” — put forward by Alfred North Whitehead. Circa 1929 Whitehead broke with the materialistic view that’s been with us since Plato and which continues to haunt debates about quantum mechanics.

  • Older readers of science fiction will recall Alfred Bester’s “The Men Who Murdered Mohammed,” in which “it is the nature of time itself that confounds time travelers—history is personal, in Bester’s memorable metaphor it’s like a strand of spaghetti for everyone, and when you change history you become like the spaghetti sauce, detached from the world. So you can go back in time and change it, and it doesn’t change it for anyone except yourself.”

  • Could it be that what we are experiencing as this collapsed wave function (The Copenhagen interpretation), is really not that at all. Perhaps the wavefunction is there, still ripe with all of the superposition of possibilities. Perhaps the collapse (as it has become to be known) is really just a projection to our lower dimensionality, where we have been able to peer at a lower dimensional slice of a higher dimensional reality? Take a hypercube, for example – that is 10 dimensional. These degrees of freedom in the higher dimensional space (that we can’t observe, measure, or see) represent the superposition of all possibilities that is captured in the wave function. Now, all of these possibilities in the wave function are really just describing a real hyperdimensional object that exists in a singular state. If you existed in this higher state, you would just see a hypercube, not a combination of different possibilities. But, when a lower dimensionality observer tries to measure something about the hypercube, they must take some lower dimensional slice, or lower dimensional intersection of the object as the measurement (like a 2d plane intersection of a 3d cone). We now say it has collapsed into this one particular possibility – but that’s not true at all. The hypercube still exists in the higher dimensions. So in this sense, these measurements are completely observer-centric, in that the slice “you” get, may be different than the slice that “someone” else gets, but the hypercube is still the objective reality that hasn’t been altered in any way by either measurement.

  • The question according to Steven Goldman at Lehigh University is not just whether something is ‘true’, but is it true with a Capital ‘T’.
    This issue is cogently addressed in a Lecture Course entitled
    “Science Wars: What Scientists Know and How They Know It” (2006)

  • I like the subtitle change. What would be really cool is if I went back to the Quanta email I clicked through to get here, and found it had changed there too, but reality is apparently not that malleable.

  • The “wave function” of Quantum Mechanics (wherein the quantum system inexplicably transitions from multiple simultaneous states to a single actuality), does not describe the world — it describes the observer …
    For some it is a shortcoming of the theory, for some it is the beauty of it: it is what Quantum Mechanics has been trying to tell us all along — that a single fixed, finite, objective reality is an illusion, the real comes about when observed, that reality is not made but is in the making …
    If you are a physicist only you might quarrel with this interpretation, but if you are a physicist of philosophical bent like the architects of the Quantum Theory have been, you are fine. More than fine: you have un-covered the secret of co-creation …

  • Great article. Yet a lot of what we assume to be “subjective” experiences are actually universally shared phenomena of consciousness.

  • “The usual story of Bell’s theorem is that it tells us the world must be nonlocal.”

    That’s just wrong. The standard interpretation of Bell is that QM is nonrealist. Nonlocality is incompatible with relativity, which no competent physicist is willing to give up without good reason.

  • Here’s my problem with QBism: it’s observer-centric. It feels more like a way of thinking than a fundamental physical issue. The same rules ought to apply to vacuum as to observers. I like to think that the world is deterministic but that we simply have limits to our information which force us to consider issues in terms of probabilities. That is on us, not on the universe. Seems a shame to assume that the universe must work probabilistically simply because that is how our brains work.

    However, given that information is just a propagation of causes and effects, it stands to reason that no single piece of spacetime would receive “full information” about the universe, and so that space-pixel would only be capable of acting according to the information propagating to it.

    Such limits to information transfer could cause a sort of deterministic probability: things seem to behave probabilistically only because everything has limits to information.

    I guess I just feel like “observer” is a fairly arbitrary thing for us to base physics on. If a tree falls in the forest, it makes the air vibrate, but “sound” requires an observer. Similar principles ought to apply to quantum stuffs, dangit!!

  • Christine de Suede’s comment really jolted my world. Thank you Christine for giving me a new thought puzzle. I’m going to read that book!

  • Reality cannot be an illusion, because even as an illusion it is the only thing we got and illusion becomes the reality. Wavefunction collapse? What is it that collapse? A probablity? how can a probability collapse? To collapse it must be a physical wawe in a physical medium, and then we need an explanation for what medium ( a wave in what). Testable physichs please. Anyway this guy seems to have missed the last 15 years of physics development.

  • not buying it. each observer may have their own reality yet only one set of data reveals its own pertinence. under his system there would be as many as the mind can think of. and are not.

  • ‘….idea that maybe ultimately there actually are no laws of physics….’ I’m a interested layman but strangely enough I have thought something similar to this quote for a long time. I don’t believe the Universe (inclusive of extra dimension, compactified or not, etc) is a ‘mathematical machine’…although I do appreciate that some scientist do think it is based on Information… and it is we who decide that it follows certain patterns. Therein is the problem. We have to classify everything we see and if we can’t then we either dump it or begin a ‘new classification’. To me, the Universe functions as changing from one state to the next in the only way it can…by the properties it contains. For example, many find QM ‘duality’ a problem but as a Martial Artist of many years I have grown up ‘duality’ being all around us, in the physical sense. If duality is present on the macro scale why not on the micro scale? For example, e- and e+ produce gamma rays and vice versa so doesn’t that imply that e- & e+ are composed of certain formations of photons? Reality is more difficult and I know there is a lot of research going on about consciousness and QM. The camera doesn’t lie, I hear, but then we make a camera according to what/how our eyes/brain interpret the incoming signals. Wouldn’t other instruments follow the same road?

  • What is described here is a “hidden variable theory”, exactly what Einstein believed, and what was ruled out by Bell’s inequality. I am left with the impression that he just doesn’t understand the profound implications of Bell. If there is more than wishful thinking here, he needs to explain better what it is.

  • I’m glad I could offer a useful suggestion about the subhead!

    I had thought about commenting on the figure caption as well, but I figured that one complaint was enough. On further reflection, though, it’s a complaint that needs to be made.

    QBism is not a hidden-variable theory, although the figure caption is rather misleading on that point. The statement “A quantum particle can be in a range of possible states” implies that a “state” is a property of the quantum particle, whereas QBism actually maintains that a quantum state is a tool of an agent: states lie on the subject side of the subject/object divide. A particle is not “in” a state; a state is ascribed to a particle.

    “She didn’t know where the particle was before the measurement. Now she does.”

    This is similarly misleading. It would be better to say something like the following:

    “Before the measurement, she didn’t know what would happen to her when she interacted with the particle. After the measurement, she can update her expectations for her future experiences accordingly.”

    Really, I’d change the figure caption to something more like this:

    “In the textbook way of doing quantum physics, a quantum particle has a “wave function” that changes smoothly when no one is looking, but which makes a sharp jump or “collapse” when the particle is observed. QBism argues that this collapse isn’t mysterious. It just reflects the updated knowledge of the observer. Before the measurement, she didn’t know what would happen to her when she interacted with the particle. After the measurement, she can update her expectations for her future experiences accordingly.”

    There is in fact a great deal to be said about J. S. Bell’s no-go theorem in this regard (as well as the related theorems of Kochen, Specker and others). If quantum states are states of information (or expectation, or knowledge, or belief) then Bell–Kochen–Specker affects what they can be information about. See this by Fuchs, in particular section 5, for technical details:


    A shorter treatment is this by Fuchs and Schack:


  • Relatedly, it is interesting to see what phenomena can be described in terms of hidden variables and what phenomena cannot. This is a question that might well be relevant to understanding what resources are necessary to make quantum computers (i.e., if your “quantum computation” can be faked using mundane, classical resources, it’s not a great improvement). Rob Spekkens is the expert on this:


    Or, if you prefer video:


  • “I think the biggest fear people have of QBism is precisely this: that it’s anthropocentric.”

    That is one of the teachings of the ancients schools of mysteries [1] Another teaching is that the universe is anthropomorphic.

    [1] Booth, Mark (2008), The Secret History of the World, p.25.

  • “Now she does.”
    Or does she?
    It looks to me like (from a layman’s observation) that the particle collapses into two position and the measurment she has taken is a zero sum function of the osolation between the two position. so while her measurement has isolated the position in the “middle” of those osolation, at the particle’s greatest potential, I am not sure why the particle actually has to be there. Mass seems to distribute itself without force, from where it was to where it is, so to the observer the force in its potential in any position is unimportant, except as to stand out when the function collapses.
    It then seems likely that at the time of her measurement the particle could exist at any potential between the two position (where it was and where it is going to be).
    So she, as you suggested, has a very close guess as to where its postion really is, maybe enough to actually see the particle.
    At least one close enough for horseshoes and atom bombs.

  • This comes very close to the idea that we are actually living inside a simulation:

    Untestable? Maybe… but what if so?

  • A couple of questions:

    – does QBism lead to anything testable, especially any outcome different from the other interpretations? I suspect not, and so it too must be considered to be just another philosophical musing without any meaningful relationship to the real world (not unlike the multi-worlds interpretation).

    – If a dog doesn’t have enough consciousness to collapse the wave function, what was the state of the earth and the universe in the billions of years before a human level of consciousness evolved? And on similar lines, can a supercomputer collapse the wave function? Why not (since Fuchs’ answer is almost certainly no)?

  • Each of us is the center point of our own reference frame and three dimensional space is really just the xyz coordinate system. Which is a mapping device, like longitude, latitude and altitude. So multiple frames can be used to describe the same space.

    We also experience time as a sequence of events and so think of it as a vector from past to future and physics codifies this by treating it as measures of duration, but the actual reality is a changing configuration creating and dissolving these events, so that they go from future to past. For instance, the earth is not traveling some dimension from yesterday to tomorrow, but tomorrow becomes yesterday because the earth turns. Duration is just the state of the present, as these events come and go.

    So the reason different clocks can run at different rates is because they are separate actions and/or separate frames. It is just that since we function as a particular sequence, multiple sequences equate to noise and so to measure time, we isolate a particular action, from the rotation of the planet, to cycles of a cesium atom, as a signal extracted from this noise, but the overall effect is still cumulative. That is why there is no Newtonian absolute measure of time. Just activity in the state of the present.

    Given events are first in the present, before receding into the past, they have to occur, in order to be determined. Causality yields determination, not the other way around.

    We think of temporal sequence as causal, but only energy exchange is causal. Today doesn’t cause tomorrow, in the same way that a batter hitting a ball causes it to fly away. The sun shining on a spinning planet causes this effect called days. The sequence of time is like a tapestry being woven of strands pulled from what had been woven. In fact, this makes the past material we constantly reuse to create the present, as the energy that manifested it progresses to different forms. Since it was dependent on the frame when it occurred and the frame through which it is perceived continues to evolve, the perception of past forms is constantly changing.

    So perception does create our reality. Much as we still experience the sun as rising in the east and setting in the west. It is a matter of peeling away the layers creating this perception, to comprehend how it is created.

  • Nothing new here: qbism = copenhagen (see http://motls.blogspot.com/2014/09/bohr-heisenberg-landau-wouldnt-find.html). Copenhagen has always held that the wave equation is about what each “observer” can know, not a model of objective reality (about which it remains neutral). See the Motl blog for before thinking qbism is a revolutionary insight.

  • Why does every believe that wave functions collapse? “From chaos … find order.” Consider tranformation, even if it seems ridiculous.

  • Josh Mitteldorf, no you’ve misunderstood QBism. QBism is not a hidden variable theory and is perfectly compatible with the Bell theorems (both of them). The way it works is described in the article in fact: quantum states describe states of individual agent knowledge, not states of the world. Quantum states in QBism have no objectivist obligations so are freed of the responsibility of giving a causal explanation of Bell correlations (as a hidden variable theory has to do). I.e., QBism makes no attempt to “explain” the cause of any event in mechanistic terms. I recommend reading up on Bayesian probability if this doesn’t make any sense. It’s a well developed classical theory of probability (hundreds of years old), but applied for the first time to quantum systems in QBism.

  • To elaborate on Bell’s theorems:

    The two commonly stated assumptions of Bell theorems (locality and reality) are in fact part of a network of multiple assumptions or axioms which have been carefully teased out over the years, but are often left implicit in the discussion. This is nicely explained in http://arxiv.org/abs/1503.06413.

    Summary of Bell’s theorem: Quantum phenomena are incompatible with _at least one of_ the following (nomenclature explained in the above article):
    1. Macroreality
    2. Minkowski space-time
    3. Temporal order
    4. Causal arrow
    5. Free choice
    6. Relativistic causality
    7. Common causes
    8. Decorrelating explanation

    Typical hidden variable theories, like Bohmian mechanics (which does work!), throw out 6. I.e., hidden variable theories necessarily require faster than light causal influences (though these still cannot be used to transmit matter or information). The traditional (Copenhagen) interpretation throws out 8: there is no need for quantum correlations to have a cause. QBism takes a very different approach from all other attempts in quantum foundations: throw out 1! QBism says quantum states are states of _agent knowledge_, not states of the world. Quantum mechanics, according to QBism, has nothing yet to say about external objective reality (macroreality). It only describes how agents interacting with external reality create and take part in subjective experiences. That doesn’t mean that an objective external world doesn’t exist, only that it’s nature is still a mystery, one not addressed by quantum theory.

  • In it’s attempt to divorce itself from philosophical speculation, theoretical physics has lost its awareness of metaphysics, which is inquiry into the nature and workings of ultimate reality. The 2 branches of metaphysics are: ontology, which deals with the question, What is? What is there? What is real? What really exists? What is reality like in itself?; and epistemology, which deals with the question, How do we know? How do we know what is, what is there, what really exists? Heisenberg uncertainty is explicitly a measurement problem, our inability to “know” both the precise location and the precise momentum of a small fast particle (like an electron) at the same time. This is epistemological uncertainty — Heisenberg told us something about the limitations of our ability to know about the objective reality of the electron by measuring its behavior. It is not ontological uncertainty: Heisenberg told us nothing about how objective reality is in itself. It is not “the electron” that is uncertain. It is “the observer” who is uncertain. QBism is correct: probability is all about our lack of complete knowledge. We cannot “know” without “looking”. Our direct knowledge of reality is limited to the empirical, supplemented by whatever we can figure out about the causal/logical consequences of the empirical. We can’t “know” that our logical extrapolations will match objective reality, so we have to “look” again, to see if reality behaved the way we thought it would. Untestable extrapolations and unobservable outcomes are “speculations”, in the old tradition of philosophical rationalism of Plato, Descartes et al. The rationalist project of acquiring “certain knowledge” of “everything” crashes on the shoals of the very local and particular nature of our empirical/observational means of acquiring knowledge of “what is”. In this state of epistemological ignorance, it requires a logical leap of faith to conclude that just because “we” cannot know with hard rational certainty, means that objective reality in itself (ontology) is fundamentally and essentially probabilistic and uncertain rather than concrete and deterministic. To “believe” with hard certainty that your logical leap of faith transported you into Certain Truth and Objective Reality, is a religious act, not a scientific act. Metaphysical awareness can dissuade this kind of logical error.

  • “The Copenhagen Interpretation” is a rather ill-defined term, historically speaking. It implies that Bohr thought essentially the same as Heisenberg, Pauli, Rosenberg, Landau and Lifshitz, etc., but this was not the case. The historians of science who have dug into this write that the idea of a common opinion, a unified “Copenhagen Interpretation,” is a myth invented much later, largely by Heisenberg in the 1950s.

    D. Howard, “Who Invented the ‘Copenhagen Interpretation’? A Study in Mythology,” Philosophy of Science 71, 5 (2004): 669–82.

    K. Camilleri, “Constructing the Myth of the Copenhagen Interpretation,” Perspectives in
    Science 17, 1 (2009): 26–57.

    But if you pick an exemplar of Copenhagen, it’s not hard to see the difference between their interpretation and QBism. David Mermin does so here:


  • And yes, I’ve read Motl’s response to Mermin. It gets a significant amount of major points wrong. As best I can tell, he doesn’t really grasp the way QBism responds to the Wigner’s Friend paradox. For example, Bohr and Heisenberg disagreed about the “Heisenberg cut” [http://arxiv.org/abs/1502.06547].

    “First, you know, a new theory is attacked as absurd; then it is admitted to be true, but obvious and insignificant; finally it is seen to be so important that its adversaries claim that they themselves discovered it.”
    —William James

  • Argh! I forgot to include my favorite quip about “the Copenhagen Interpretation.” It’s something Asher Peres once said: “There seems to be at least as many Copenhagen interpretations as people
    who use that term, perhaps even more.”

    I’m happy to see that the SIC question got a little mention at the end of the interview. It’s exactly the sort of thing that discussions of quantum foundations so often lack: a fun mathematical investigation. QBism has motivated a reformulation of the mathematics of quantum theory, which brings out new interesting features, though the project is still incomplete. See the Reviews of Modern Physics paper at http://arxiv.org/abs/1301.3274 and the Quantum Information & Computation one at http://arxiv.org/abs/1312.0555 .

  • Does Qbism imply that rather than the cat being both alive and dead, or neither, until someone looks, that the uncertainty is only that the observer does not KNOW about its status? This seems to tie in with Qbism in that it’s our knowledge that’s limited, not that reality is unreal.

  • I belive that both QBism and Copenhagen are pretentious explanations of something much simpler.

    Nature randomly, microscopically, jumps with half-life ~10^-43 secs and then unitarily evolves the entire universe (state vector) so that the rest of the universe knows what has just happened.

    It is a rotation (unitary) because otherwise we’d get quantities tending to infinity.

    Free-will is just evolution’s 4 billion year attempt to interact with the random jumps

    God is subtle, but not malicious.

  • I have to say, my understanding of QM is limited, but when i see stuff like “non local”, “subjective”, “consciousness”, i think of Deepak Chopra! – And that is never a good sign for a hypothesis.

  • It’s a fun idea to think about and even just trying to disprove it makes you question all you’ve learned in physics. I’m happy quantum mechanics makes us question about reality, I always found it annoying that physicists rarely take a moment to doubt on the existence of reality. And undervalue philosophical and meta-philosophical questions. in general.
    I found the flavor of QBism somehow similar to the notion of space an time in Kant, in the sense
    that you need a ‘subjective space’ in which to place what you experience.

    A few questions :

    – So the outcome of the experiment will depend on who’s watching? Different ‘observers’ repeat the experiment big N times and get ‘statistically personal results’?
    – I don’t get how you will access information instantaneously about an experiment done remotely far away … How could communication between ‘observers’ be faster than light ?
    – Would the theory be capable of doing predictions at all?

  • QBism’s stance on “reality” sounds very close to oriental philosophies, in particular the Buddhist view that neither mind alone nor the object alone can exist in itself (this leads to absurd conclusions), but rather that only the interaction between them creates reality.

    I wonder if Chris Fuchs was inspired by this, or at least looked into possible links.

  • BTW Indian philosophy speaks of a construct called Maya. It subsumes mental models but also states that the observer creates the world around themselves by merely participating in it.

  • @Johanna Fuks

    The outcome of an experiment doesn’t depend on who is the observer, but EACH observer cannot know the outcome unless he/she makes a measurement.

    So one person can look to see if the cat is alive and update their subjective knowledge about the universe, but for people who have not looked (or asked someone who has looked) the state of the cat is still in superposition.

    In my (simplistic?) model of a universe evolving by random jumps, the entire universe is in superposition for ~10^43 secs at a time, but if there is no one to make an observation then the universe is effectively in superposition for ever (since we can’t know what evolution path the universe has taken without making a measurement)

    And even if one person makes a measurement, she/he only updates her subjective knowledge about the state of some finite part of the universe (some finite part of the wave-function/state-vector of the universe)

    The superpositions are a mathematical tool for making probabilistic predictions, QM is a mathematical framework, we only need a model where the superpositions exist mathematically for the model to describe nature (including quantum zeno experiments and similar) – in particular we do not need “real” superpositions or splitting many-worlds and the like.

    Nature can be real and also (fundamentally) probabilistic – but it is in superposition for each observer until an observation is made.

  • @Johanna Fuks

    “So the outcome of the experiment will depend on who’s watching? Different ‘observers’ repeat the experiment big N times and get ‘statistically personal results’?”

    An experiment repeated N times is, philosophically speaking, one experiment with a larger budget. QBism says that I can use quantum theory to manage my expectations for what might happen to me if I perform the cheap experiment, or if I perform the expensive one. Either way, my probabilities don’t have to be your probabilities, or vice versa.

    ” I don’t get how you will access information instantaneously about an experiment done remotely far away …”

    That’s the beauty of it: you don’t! If a physicist—let’s call her Alice—writes down a quantum state for a system far away from her, that state is nothing more (and nothing less) than an encoding of her expectations for what might happen to her if she were to go over to that system and interact with it.

    Suppose that Alice is planning an experiment on a system that breaks into two pieces. Both pieces start in her lab. One of them stays in the lab, and the other flies off into the distance. Alice writes a quantum state for the pair of them, which stores in mathematical form her expectations about what she might experience should she interact with one or both pieces. She can poke the nearby piece and stimulate an experience in consequence. As a result, she might update her catalogue of probabilities for what might happen to her if she were to travel over to the distant piece and poke it. But this is not a *physical* change for the distant piece. It’s just Alice, changing what she thinks about the answers the world might give her.

    The consequence of the interaction doesn’t exist before the interaction. (Slogans from a couple physicists who were influential upon QBism: “Unperformed experiments have no results,” to quote Asher Peres; “No question, no answer!” said John Wheeler.) Nothing physical changes in a faster-than-light way.

    “Would the theory be capable of doing predictions at all?”

    Well, that’s what it’s built to do: the key issue is that the subject matter of those predictions are personal experiences.


    The major philosophical input to QBism has been the movement known as pragmatism (or “American pragmatism”), associated with John Dewey, Charles Sanders Peirce and especially William James. Bits and pieces from other philosophers have showed up, too—Bergson, Renouvier…. I’ve heard the QBist interpretation of quantum measurements compared to Whitehead’s “throbs of experience” (evocative phrase!). These are all European and American thinkers, but the project of QBism is far from complete!

  • “The two commonly stated assumptions of Bell theorems (locality and reality) are in fact part of a network of multiple assumptions or axioms which have been carefully teased out over the years, but are often left implicit in the discussion.”
    So one assumption is that it is in our genes.
    So an assumption is aposition? One position of many?
    And maybe it is as I suggested: she doesn’t know the exact positon, but good enough.
    I mean what are we talking here, 15 decimal places as in AutoCAD?
    Or maybe 1/60?

  • “the stuff of the world is in the character of what each of us encounters every living moment — stuff that is neither inside nor outside, but prior to the very notion of a cut between the two at all.”


    The only way to theorize about the stuff of the world with any useful degree of accuracy is to make conceptual cuts in it. All that can be said of reality, absent such cuts, is tautologous: it is what it is.

    Cutting it into past, present and future looked harmless for a while, but Einstein showed us that getting even that seemingly easy cut right involves previously unsuspected subtleties.

    I can see no in-principle reason why reality as a whole should be expected to conform to any set of laws. There’s a long history of success at constructing lawful descriptions of parts of it to yield useful predictions, much of which comes down to judicious placement of conceptual cuts. However, the success of science as a method of inquiry does not, to me, imply that our finely tuned models of reality must constrain reality in some way. It just does what it does, whether or not we choose to use labels like “electron” and “photon” to identify recognizable parts of events we’re accustomed to recognizing.

    Reality is experiencable – we are all living, breathing parts of it – but acts of recognition and description must necessarily involve the use of conceptual models, and are therefore inherently subjective. What we think of as objectivity, therefore, is in fact consensual subjectivity: a method that yields predictions generally agreed to be useful, and whose accuracy depends on the care exercised in their use.

    Why the quantum? Because it works.

    Why do the physical constants have the precise values they do? Because those are the values that work. Make an arbitrary change in a physical constant, and the equation of which it is a part no longer models reality correctly.

    Why is there something rather than nothing? Category error. “Nothing” is by definition a word without a referent, a mere linguistic place-holder; “something” always refers to some part of reality. “Nothing” is something; nothing isn’t.

    Is nature fundamentally probabilistic? Category error. Our best available models of it certainly are.

    I don’t think QBism requires us to stop thinking of reality as real. I think it requires us to stop thinking of it as repeatable. I’m comfortable with that.

  • “Could it be a dog? (“Dogs don’t use wave functions,” Fuchs said. “Heck, I didn’t collapse a wave function until I was 34.”)”
    A dog doesn’t use wave functions?
    OK, so now I see where this is going.
    What we are talking about is faith-based research, i.e. a dog doesn’t collapse a wave function, because it doesn’t have a soul. The observer is in another kingdom, and to enter the kingdom not observed, you need a soul.
    And I am not saying that faith-based research is not legit. I am just saying that it has a bias, and that bias eats up research dollars that could go to Liberal researchers who would otherwise need and use capital that is not available to them, in such a way as it is to people like Fuch, i.e. people of faith.
    I appologise for lending my thought into the narative of this web site, as I am a person of little faith.

  • Not too sure I understood that. But in a universe where anything can happen, sooner or later it surely must. In possibilitist terms, hopefully we will be there to look over some objective observer’s shoulder as they try and tell us the story of what they think just happened.

  • The universe is inherently a timeless ,causeless ,changeless ,spaceless and static mathematical structure . Universe should be conceived and understood in different scales and eras ,in some low energy scales notions such as time ,change,dynamic ,causality ,evolution getting meaningful but not in deep down there . Reality simply exists without boundary ,it is only atemporal ,eternal thing and observes are just a part of it . for understanding of universe around us we need to invoke our minds but this is only a condition and restriction imposing to us not to universe , maybe universe even doesn’t need to be explained or understood by any observer . let’s suppose everything is just observation and exist only inside the mind of observers ,so I am really wonder someone tell me how universe can be explained in planck scale or in big bang singularity which surely no mind or observed can persist altogether ? Last remark : even information is made of mathematics ,without mathematics defining ,explaining and comprehending of universe is absolutely impossible ,in particular at the very beginning of universe s0-called initial singularity of big bang !!!

  • If a phenomenon cannot be measured and experiments performed on it by independent people, then the explanation for that phenomenon is not (established) science. Science is not defined as anything that scientists do or believe.

    In my opinion, Dr. Fuchs has taken quantum mechanics to its logical conclusion, and demonstrated that it is not science (as I defined it). At least not yet. Uncertainty means that we do not know — not that nature doesn’t know. The need to construct a Copenhagen Myth proves that physicists don’t agree, as well as their need to conceal their disagreements. That is not science, either.

    On the other hand, Dr. Fuchs has not offered science to replace quantum mechanics. After exposing it as philosophy, he simply offers a different philosophy in its place. Nature requires a physical explanation, and in my opinion QBism is not it.

  • I would be very curious to know if Mr. Fuchs has ever read Kant’s Critique of Pure Reason.

  • Dear Mr. Christopher Fuchs, Not to burst your bubble, but I came up with a similar realization last year on a facebook posts to my friends. I based my conclusion on the simple fact that we measure (i.e see, hear, taste, feel, etc.) is the effect, not the cause; and at best is an approximation (or representation, echo) of the nature of the cause. Take for example any elementary particle: what we infer about its nature or properties is glimpsed based on its interaction with our measurements/observations (i.e its effect), while its cause and nature remain hidden. Additionally, because each observation is unique (and we build a picture of our objective reality based on these unique measurements/observations) it stands to reason that each observer reality (or each measurement/observation) is also unique.

  • The way we interpret coherent superposition is wrong; or at least incomplete. To wit: We plot the wave function along two axis, (x) to represent position and (y) to represent probability. At any interval (collapsed state), x will contain a single value for position; and a single value for y, the value of the probability (1, or 100%). The problem with this is that we are expressing a three dimensional (or rather a multidimensional event as a two dimensional measurement. The third axis, let’s call it (z), represents at each interval the probability 1 (or 100%) of each alternate or parallel universe/reality. But because in our calculations and representations we ignore the (z) axis, or rather we measure it edge-on, the wave function “seems” to collapse into a finite value at each interval. Now if we could “rotate” along the (y) axis, so that each probability on the (z) axis is “visible”, then we would “see” that at any interval, while the (x) and (y) axis contain a single “collapsed” value, the (z) axis still contains all possible values. I suspect that since each one of us is embedded in a single universe/reality (we all view the z axis “edge-on”) it is beyond our capabilities to “rotate” the (y) axis and “observe” all the possible values of the (z) axis (such as x,y,z1; x,y,z2;…x,y,zn)

  • I liked the reminder about the Greek concept of excluding the subject from discourse – but many times it is important to avoid bad inferences eg “Broccoli is terrible”, vs “Broccoli is terrible to me”.

    I have often noted that “time” is also absent from much of our language.
    For example, in the author’s quote. “When we say the speed of light is the ultimate speed limit, we’re saying that we can’t go beyond the speed of light.”

    Compare this to: “When we NOW say the speed of light is the ultimate speed limit, we’re saying that we can’t go beyond the speed of light AT THIS TIME IN HISTORY”.

    This just makes the problem of induction central, and time takes center stage. (Can it be proven that a statement in Physics which is true now will always be so – seems close to what J.A. Wheeler was saying)

    I am curious as to whether the role of the subject in QBism could be replaced by the position of the subject in space-time together with the collection of all positions of the subject in space-time up to the point of measurement pus some corresponding set of measurements/information along those paths?
    Clearly making the subjective more “objective” is desirable, since there are good reasons for the split between objective and subjective.

    Yet another interesting article, Quanta magazine is the best!

  • QM is wrong; dark matter is distorting our observations, that’s why atoms work totally different than what we think to observe.

  • Everything we experience is an observation and observations by their very nature, are relative to the observer. As our ability to observe improves, new laws of Physics are developed to account for the new data. The interesting thing is that repeatedly concepts that helped us to understand at one stage become an impediment to understanding in the next.

  • I figured that sooner or later I’d come across a qualified someone who sees things the way I’ve gotten to. The guy is of course, brilliant! (Since I agree. ;))

  • Qbism sounds like crap. The Standard Model of Particle Physics is the MOST successful predictor of particle interactions. It is backed by years of experimental evidence from the likes of CERN . Fermi Lab and a few dozen other particle accelerators. It uses QFT consistent with both GR and QM. ( general relativity and quantum mechanics. ) Does he address this issue?

  • “Klavs Hansen says:

    If the wavefunction describes the observer, what describes the electron?”

    The observer describes the electron! Nothing in modern science calls for the concept of “particle”. We should try to free ourself from concepts inherited of classical physics and see if this helps moving forward in developing further reaching theories (in particular QM+GR)

  • Finally, we have something that makes sense. I have always been thinking on the same lines as QBism. Up until now, people have misunderstood the interpretations of quantum theory. They made the theory itself an objective reality.

  • Maybe we are in the entire universe – all of it, all at one time. This makes distant travel just an awareness. “There” could literally be right “here”. It’s an inspiring thought to be without time or gravity. Measurements, much like religion, box out the possibilities and trap our minds in cornered dimensions. Ask children how to get to Mars and they will tell you the truth (no formulas needed). If it is in our thoughts, it is attainable. Perhaps, if we set aside the laws, stop telling our minds that a=b then possibly, a=anything/everything. Perhaps, trusting the chaos just like we trust oxygen would expand possibilities exponentially. Please don’t tell the bumble bee that he is not able to fly…lest he like us, fall from the sky.

  • QBism might be a step in the right direction, but, so far as I can see, it conforms to the long tradition in physics of using probability as one of its ways to avoid facing up to the fact that human minds are much more than passive observers.

    It is obvious, isn’t it, that minds are responsible for much of what happens here on Planet Earth, and nowhere else that we know of? Twentieth Century physics chose to ignore minds in the fond hope that minds are either illusions (whatever that might mean) or will in due course be reduced (whatever that might mean) to a mindless physics. We have chosen to forget the clearly stated belief of John von Neumann that minds (the observers of quantum phenomena, the inventors of instruments, the designers and performers of experiments) are indispensable for our understandings of phenomena (understandings that are reached by minds arguing, experimenting and often agreeing).

    Unfortunately, the attempts, by Wigner and others, to realise von Neumann’s idea, failed to impress a professional world of physicists possessed by the belief that what we see out there is an objective reality, independent of our seeing it. That faith, called “realism” by philosophers, must be given up if we are to bring minds into physics, and giving it up is not easy. My Apple iBook MINDFUL PHYSICS — A NEW ACCOUNT OF WHAT HAPPENS introduces an alternative to “realism” called RADICAL EMPIRICISM. If radical empiricism had a slogan, it might be LOOK WHERE YOU CHOOSE TO, BELIEVE WHAT YOU SEE AND QUESTION WHAT YOU ARE TOLD. From that, a new extended physics emerges that takes account of minds and accounts for them, while rejecting next to nothing of the mind-ignoring physics of the 20th Century.

    The case for mindful physics is long and cumulative, and cannot be related in a few words. Let me just say this. Your mind is what you experience, and that experience is private; though you may talk about your experience, no-one else has your experience. That is what it is to be YOU. For every other individual mind it is the same. Your private ACTUALITY, greatly constrained but also somewhat free, happens in your private time, a time in which it is invariably NOW, with a past that is only remembered and a future that is only anticipated. Out of the private actualities of individual minds, agreements that are made produce a multiplicity of agreed REALITIES, of which the objective world of physics is just one, but the one that is most compelling and most useful. (Those agreements, I suggest, are down to the harnessing of quantum entanglement by/as our shared human Mind.) To recognise that the world physicists agree about is not independent of minds does not diminish that world, but opens the way to our seeing a timeless underlying geometry that is far more mysterious than we have imagined.

    That briefly summarises what I call TAKING ACCOUNT OF MINDS. As to ACCOUNTING FOR MINDS, mindful physics sees your individual brain/mind as an individual physical process sustained by your brain for so long as you live, of alternating coherence and decoherence. Your brain is an immensely complex physical system, different from all others, that generates the mind, different from all others, that you privately experience in those moments of decoherence.Yours is just one of the many brain/minds that have acquired this amazing ability, thanks to the very long evolution that serendipitously has produced a species that copes better than other species with the place where it finds itself. That place, increasingly is made, for better or for worse, by human minds.

    Mindful Physics opens up big opportunities in physics to whoever takes up the task of integrating it with the best of twentieth century physics (including Quantum Field Theory, relativity and string theory); big opportunities in philosophy to those who can bring themselves to figure out what follows from radical empiricism, and what is washed away; big opportunities for neuroscientists to discover how the neural circuits of each individual brain implement the individual quantum process that generates/is its associated mind; and big opportunities for quantum engineers to design and build toy brains/minds that better simulate human brains/minds.

  • rewrite the atomic theory and math
    instead of orbiting electrons think 3D…
    radial expansion …contraction
    iaw general relativity
    make a Bohr atom into a new model
    re work the math…keeping and updating the rules ..
    see what you come up with….i recon electrons pulse like this absorbing and emitting at each turn of tbe accelerated fieldthe mass comes from the change of accn.
    try it out see what you get

  • I agree with Dr. Fuchs ideas in that the collapse of a wave function may say more about the mathematics and approaches we use in QM than about the objective nature of exactly what is going on. Has anyone stopped to consider what a different mixture of "popular" mathematics might have produced if we had tapped the power of the atom at a different time? Instead of using statistical approaches (a la wave functions based on the math DISCIPLINE of probability, and not necessarily an objective feature of reality itself) what if we had been in a physical silicon-based computer phase and decided to describe reality in terms of waves instead of particles (which interestingly enough make the symbolic math a lot easier) such that we went the opposite path of particle-based physics, that of waveform based physics (interstingly enough something I did about 10 years ago using numeric analysis and automatic differentiation).

    So I agree with Dr. Fuchs. Maybe his insistance that the collapse of a wave form through observation shows, by reflection, an inherent weakness in the scientific context that QM evolved in, and is NOT an intrinsic feature of reality but comments more on our consciousness, our approaches, and even our mathematical systems.

    In lay man's terms (maybe even a dog's), all a collapse of a wave function means is here are the areas (volumes) in which there is a high probablity of finding the particle, and through observation, we indead find it there….most of the time lol. And here it is over here, in a low probability area…oooh, but wait, when we do the experiment over and over again, we find out that it wasn't founf there most of the time.

    In other words, we haven't made a great insite into reality….we've just proven the mundain principle of how posibility works: when there is a high-probability of something occuring, it happens most of the time, when low it hardly happens in reality.

    The point: the mathematics of wave-function collapse through observation says more about the math system of probability than it does about th reality of micro worlds.

    An interesting point of view….and horribly practical. Have to say.

  • As stated, "…it’s not that the world is built up from stuff on “the outside” as the Greeks would have had it. Nor is it built up from stuff on “the inside” as the idealists, like George Berkeley and Eddington, would have it. Rather, the stuff of the world is in the character of what each of us encounters every living moment -", as [good grief] Johann Gottlieb Fichte would have us believe; {8~(

  • Consciousness is the modulator for me..each individual view collapses the local wave so we can interpret it to inform our individual reality..it's only real inasmuch as it fits our design of the universe and it is anything but permanent..a mere flash in the pan. The fabric of space-time requires the illusion evolves into another experience, and another and another, until we, the perceiver, returns to pure consciousness through death leaving the physical/material world….

  • OK it sure seems strange to equate a mathematical tool with a personal belief. This must be some new math recently developed. I think I am going to win the lottery so I develop a mathematical tool which provides the prediction that I will win the lottery because this reflects my belief. I wonder how well that will work out.

    Putting this deep mathematical question aside , let's do a thought experiment. We have two different people , one in the United States and one in India. So as not to contaminate our experiment we insure both people are totally ignorant of quantum mechanics. However, we teach both of them how to perform a quantum measurement experiment. Now there is no reason to think these two people share the same belief that the quantum system they measure has a specific property. In fact they are so ignorant of quantum mechanics they almost certainly have no specific belief about any property at all. OK so they both perform the exact same experiment. Will their results agree? If yes ,since they shared no belief that the quantum system they measure has a specific property how could it be that their results agree? Remember the quantum state reflects a belief, not an objective fact about reality. What would a Qbist say about this?

    Bob Zannelli

  • Color me skeptical.

    1) Does QBism generate any testable hypotheses, and if so, have the relevant experiments been performed, and what were their results?

    2) Does QBism provide a better account of what we observe, than does the Standard Model? Here I'm not looking for a comprehensively better account: a few examples would suffice to demonstrate that there's something to this.

    3) How does QBism address the repeatability and observer-independence of classical phenomena?

    The point that subjectivity informs and alters our observations, has become more or less mundane in various contexts. Minds make a difference in translating raw observation to data and then to conclusions. But the idea that subjectivity is, at root, _all there is_, risks sliding down the slippery slope to solipsism.

    In the end, if QBism proves to be untestable, then to my mind it joins the ranks of other untestable theories as items of faith, that might be studied in a context of "comparative science," by analogy to comparative religion. That exercise wouldn't seek to ascertain which untestable theory is "correct" (any more than comparative religion can determine whose deity is real and whose is not) but would, as with comparative religion, examine the core beliefs, ancillary beliefs, societal implications, and so on.

    But in the end, what interests me more, are theories with empirical backing. Because in the end, I believe that reality exists.

  • It's all fine and well to read about but the anthropocentrism is just a big no no.

    It's surprising that such a question is so quickly evacuated. One can understand the narcissistic attraction from over thinkers who spend a lot of time trying to figure stuff out in one's brain.
    But I wish this was addressed properly as the big elephant in the room that it is.

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