Wigner’s Friend Didn’t Invite Him To The Party

Wigner’s Friend Didn’t Invite Him To The Party

From reader Caleb Hansen comes this email:

I hemorrhaged brain cells while reading this article from “Interesting Engineering” and thought to share it with you.

[link to article]

The experts get so giddy when “disproving” objectivity with “the laws of quantum physics” aka: their poor understanding of potency and act.

-Ad Majorem Dei Gloriam

The article is typical breathless science journalism, but it’s useful enough for us to highlight the difference between a thing’s nature and our knowledge of a thing; i.e. between ontology and epistemology.

Wigner’s initial thought experiment was simplistic in principle, starting with a single polarized photon that can have either vertical or horizontal polarization, upon measuring. The laws of quantum mechanics hold that a photon exists in both states of polarization simultaneously, in what’s called superposition. In his thought experiment, Wigner imagined a friend measuring the state of a photon in a different lab, and recording the result while Wigner watched from afar. He has no clue what his friend’s measurement is, and is thus forced to assume that the photon and its measurement are in a state of superposition of every possible outcome for the experiment.

Wigner can say, however, that the “fact” of the superposition’s existence is real. And, strangely, this state of affairs suggests that the measurement can’t have taken place. Obviously, this stands in direct contradiction to Wigner’s friend’s point-of-view, who just measured and recorded the photon’s polarization. He can even call Wigner and tell him the measurement was taken, without revealing the results. This means there are two realities at odds with one another, and “calls into question the objective status of the facts established by the two observers,” explained Proietti and colleagues, in an MIT Technology Review report. And the new research reproduced Wigner’s thought experiment by using entanglement techniques for many particles at the same time.

“Calls into question” is equivalent to “questions raised”, a trope and trick used in journalism to create the illusion of objectivity.

Let that pass, and let’s do Wigner’s Friend Iterated. Wigner’s pal is in the lab doing the experiment, as described. Wigner is thinking about it from afar. Yet here are you, watching Wigner. Your presence created a batch of new superpositions, now including Wigner, and we now have an even farther flight from objective reality.

And so on. If we get enough people to watch each other, nothing can ever exist, all will endlessly exist in superposition and the universe will be an amorphous blob. Clearly, this is an undesirable situation, so we must stop Wigner’s friend from performing his experiment if we want to get on with life.

This paradox, if it can be given so glorified a name, is solved in two ways.

The first accepts the standard fuzzy explanations of “superpositions” and the like, and reminds Wigner that his knowledge of the state of the experiment is not equivalent with the essence or state of the experiment itself. He is not part of it because of or when he thinks of it.

That’s easy to prove, too, using my favorite example of interocitors. These are the communication devices used in This Island Earth. Imagine the interocitor can only have three states (A, B, or C), and must take one of them. Given this, and only this evidence, what is the probability it is in state C? We deduce 1/3.

The interocitor is not in a superposition, it is in a position, but we don’t know what it is. Same with the polarization when Wigner’s friend measured it. Wigner has nothing to do with it. Even stronger, interocitors don’t even exist! They can’t really take superpositions or even positions, not ontologically, not in Reality. But we can still express our uncertainty in their state, as we do with any logic puzzle. Epistemology does not need ontology, if you like.

Incidentally, this is the same first solution (with more detail) given by “The Information Philosopher”, whose article quotes Wigner at length.

The second solution is to suppose, as Hansen, Heisenberg, and Aristotle, do, that objects are composed of potentiality and actuality, and that the idea of “superpositions” express potentiality, a form of Reality. We discussed that at greater length here: Quantum Potency & Probability (links to Ed Feser in here, who explains it better than anybody).

Briefly, it’s easier for these fundamental almost singular objects to be comprised more of potentiality than actuality, to be fuzzier and less concrete. It’s the interactions, or “measurements”, that force objects to take on more actuality—while also retaining some potentiality. Even macros objects have potentiality. You, for instance, while being mostly actual have the potential to be somewhere else.

That’s all too short, so go to the other article for details.

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  1. Things like this are why I despise, hate, and loathe the damage done to science and the popular culture by the idiocies of the Copenhagen Interpretation of quantum physics.

    Reality is real. Our knowledge of reality is imperfect. Some real things are, and will remain, unknowable.
    The map is not the territory.

  2. MikeW

    The photon exists in a quantum superposition of multiple polarizations until a measurement or other disturbance causes the quantum state to decohere into a single fixed polarization. The quantum superposition cannot be observed. It is inferred from quantum theory. The final fixed polarization can be observed. The probability of its actual measured value is predicted by quantum theory.

    Once the measurement has been made, Wigner is not forced to assume that the photon and the measurement are in a state of superposition. Instead, Wigner can assume that the measurement caused decoherence to occur, and that he can learn of the results of the measurement when he receives that information.

  3. Sheri

    “created different realities that are irreconcilable” by you flaming idiots. There, I fixed the statement. Also, forget the study. Just watch the Voyager episode where 7 of 9 crates five or six “realities” out of the same set of “facts”. Maybe that’s where these ideas occur. Physics, at the quantum level, is science fiction anyway. (Magazine should be titled “Interesting fictional engineering garbage”)

    Does anyone drug test these people???? I beleive LSD usage yields the same outcome. Plus, only flaming morons think you can prove or disprove “reality” or that thought experiments count for anything other than brainstorming. Reality exists, but many could care less. These types USED to die young. Sadly, now they survive to reproduce and write idiot papers.

    PHYSICS IS PHILOSOPHY AND PHILOSOPHY HAS NO OBJECTIVE REALITY AND NEVER DID. Repeat this 1000 times a day and you’ll realize how idiotic the world is. Also, massive drug use is rampant or damage from rampant drug use in one’s youth. (NONE OF THESE PEOPLE IS SMART ENOUGH TO EXPLAIN WHAT THEY OBSERVED SO MAKE UP CRAP. We no longer admit we don’t know everything.)

    Someone should have “disposed of” that stupid cat in a box before Schrodinger wrote his fiction.

    These people are all living in a holodeck and there is no reality. Besides, if reality can contradict itself and you can have irresolvable observations, there is no reality and we should cut off ALL grants and rewards for these obvious lies.

  4. Pat Cusack

    If a photon can be described as a “massless particle”, how does that differ from an “invisible unicorn” – which CAN travel at the speed of light, in a vacuum (if it wants to)? Can anyone prove either exists?

    Serious responses will include coherent definitions of the nouns “particle” and “unicorn” and the adjectives “massless” and “invisible”.

  5. Rudolph Harrier

    This really is typical of pop science writing. The presentation of the problem is utterly incoherent unless you already agree with the Copenhagen interpretation, and beyond that the idea that the Copenhagen destroys the idea of objective reality. (If you accept all that the presentation becomes only somewhat incoherent.) But this is all treated like it would convince any reader, no matter how much he disagreed beforehand.

    It’s really “we all f***ing love science, so we have to agree with what SCIENCE says. Now that we agree, let’s do some handwaving to pretend like we reasoned ourselves into this conclusion.”

  6. Bulaoren(Brian)

    I don’t really care, and yet I do.

  7. Johnno

    This is completely off topic, but is so stupid it needs exposure, because these are the people that will be labelled “scientist” and “expert” in the near future.

    BEHOLD! THE lowercase MOVEMENT!




  8. Rudolph Harrier

    Hierarchy in letters is traditionally indicated by alphabetical ordering. That is, A rank is before B rank, etc. Thus if she wants to reject all hierarchies, she should refuse to use any letter but “z.”

    As a handy side effect once she does that her tweets should reflect the sounds we already make as we read them.

  9. Yancey Ward

    Sorry, Johnno- I am in the People’s Judea Font for Italicizing.

  10. Incitadus

    Copenhagen Interpretation of 1864 didn’t work out so well for them.

  11. Kneel

    ” If we get enough people to watch each other, nothing can ever exist,…”

    See? Science proves that black is white, and is then run over at the next pedestrian crossing.
    In short, this is The Science that shows men can be women.
    It’s the laws of fizzicks, doncha know? Can’t argue wiv dat, can ya?

  12. Beware of pop science writers, as someone above remarked. He/she who wrote shows that they didn’t read Wigner’s original article; Wigner wrote about spin 1/2 particles, not polarized photons in the original article. However, he/she (the writer of the article, not Wigner) are not alone in their ignorance. The quote (apocryphally attributed to Richard Feynman) “Anyone who tells you they understand quantum mechanics is either a liar or a fool.” (or something like that.) Moreover, interpretations of QM are metaphysics, not science–they can’t be falsified; the Wikipedia article lists (the last time I counted) at least 17 interpretations of QM, each consistent with experimental measurements. My favorite interpreter of QM is Bernard d’Espagnat, a philosopher/physicist who worked with the Aspect group on the Bell’s Theorem experiments. He posits a “veiled reality” that won’t ever be unravelled by science. See “Mathematical Undecidability, Quantum Nonlocality and the Question of the Existence of God.” (Driessen and Suarez, eds.)

  13. Hagfish Bagpipe

    Bob: ” He posits a “veiled reality” that won’t ever be unravelled by science.”

    It will be unraveled by Briggs. Watch this space.

  14. Codex

    A few days ago I saw one if those Occasional-Coetex Be So Dum memes: OC only uses lower case letters ‘cos of the need to fight capitalism.

    It doesn’t even take a week now. No wonder the funnies are dead

  15. @Bob Kurland – I’m glad you brought up Bell.
    Bell’s inequality is not just bunk, but hokum.
    It is a mathematical sleight of hand, equivalent to a straw man assuming the premise.
    “We define X = true and X ? Y. If X ? Y, then Y ? X. By substitution Y ? true.”

  16. Stupid internet. Replace “?” with “=/=” (does not equal).

  17. Hagfish Bagpipe

    Here’s an interesting OT; on September 20, 2019, well before the Covid Plandemic rolled out, this chick in Vermont posted a video foreseeing the whole damned thing.


    She put two and two together, came up with four, and thought to warn everyone what’s about to hit. And she was exactly right.

  18. Milton Hathaway

    When we studied magnetic fields in applied physic class, we learned the equations, of course, and they also threw in a concept called “magnetic lines of force”. The latter is a hand-waving visualization technique roughly analogous to drawing gradient lines on a topographic map (drawn everywhere perpendicular to the more familiar elevation lines). Useful, yes, but with limits. Because it is a useful technique to get a better grasp on complicated subject, people tend to try to push it too far, and the conjured lines-of-force become the reality in people’s minds. As Briggs would say, the model has become the reality. People start to say things that make my brain hurt, like the lines-of-force behave this way or that way, that they interact with each other in this way, etc.

    While it creates pretty pictures, I have always found the magnetic lines-of-force model deeply unsatisfying as a predictive tool. For example, when a piece of iron is brought nearby, the magnetic lines of force get sucked into the iron. If you form the piece of iron into a donut shape, then essentially all the magnetic lines-of-force are trapped inside the iron donut. This would seem to imply that the magnetic field can’t have any effect outside the donut, but that is definitely not the case. So you have to wave your hands even faster to make the lines-of-force model again match reality.

    Only after many years out of college did I stumble across another visualization of magnetism (https://www.youtube.com/watch?v=1TKSfAkWWN0) based on special relativity. Suddenly, the deep mysteries of magnetic fields became much clearer in my mind. (Yes, we were taught that electric and magnetic fields were opposite side of the same coin, but it never really sunk in.) I still use the magnetic field equations, since they are much simpler to deal with than the special relativity equations. But my intuitive feel has now switched from the unsatisfying magnetic lines-of-force model to the relativistic movement of charges model, and I now find magnetic fields much less mystifying overall.

    I want to see QM in the same light. QM is a fact, the physicists say, because it is so spectacularly successful at predicting behavior that it must be true. But I think it’s as likely as not that there is a simpler underlying explanation yet to be discovered that is much more intuitive, and that QM in the future might be viewed less as an explanatory theory and more of a mathematical shortcut.

  19. Eric Quinnell

    So where was the “Engineering” part of that “Interesting Engineering” article? Did the guy watching the other guy measure shit make something useful like a robot toothbrush or cheapen the price of electric distribution?

    Seems that piece belongs instead in the “Here Be Dragons Quarterly” along with “multiple infinities” and “dark matter”. Extrapolating from 6 photons to “reality doesn’t exist” is pretty bold, even for the undead cat crowd, but let’s not call it “engineering” plsnthx

  20. DMA

    Milton H says:
    “I want to see QM in the same light. QM is a fact, the physicists say, because it is so spectacularly successful at predicting behavior that it must be true. But I think it’s as likely as not that there is a simpler underlying explanation yet to be discovered that is much more intuitive, and that QM in the future might be viewed less as an explanatory theory and more of a mathematical shortcut.”
    Let me introduce Randall Mills and his “Grand Unified Theory of Classical Physics”
    https://brilliantlightpower.com/theory/. He has resolved most of the problems that required quantum mechanics by realizing the shape of the electron is spherical. His work allows full descriptions of atoms and molecules as well as binding forces and other parameters. His beginning point was an attitude much like that you express in the quoted paragraph

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