rekastner

Recall that in Part I of this post, I discussed an option (ii) in which scientists make a non-scientific, metaphysical choice when they presume that scientific theories are only about the world of appearance (as opposed to a realm that may not be observable). Now, that is certainly a choice a scientist can make–but for it to be an intellectually responsible choice, the chooser must recognize that it is a metaphysical choice that goes well beyond anything mandated by the discipline of empirical science. This is because empirical science simply has nothing to say about whether there is any unobservable realm, and whether or not its theories refer to such a realm.

I’ll begin this second installment with a bad example of choice (ii) being made irresponsibly:

“The claim that the fields of modern physics have anything to do with the “field of consciousness” is false. The notion that what physicists call “the vacuum state” has anything to do with consciousness is nonsense. The claim that large numbers of people meditating helps reduce crime and war by creating a unified field of consciousness is foolishness of a high order. The presentation of the ideas of modern physics side by side, and apparently supportive of, the ideas of the Maharishi about pure consciousness can only be intended to deceive those who might not know any better. (Pagels).”

Not only does Pagels make a metaphysical (extra-scientific) assumption denying any possible understanding of physical theory as describing anything beyond the world of appearance, he even goes so far as to impute nefarious motives to those who do so. Let us return to Plato’s Cave to illustrate the problem with Pagels’ assertion. (The following is my own parable, of course.)

******

A Troublemaker in the Cave

Cast of Characters

Socrates

Bohrus

Suacus

Qbus

Pageles

Late evening, The Cave. The five prisoners are chatting.

Bohrus: Hey guys, I’ve come up with a theory that successfully accounts for what is happening on this wall with these moving shapes.

Suacus: Wow, great! Well done, Bohrus!

Bohrus: Hold on a minute, I’m not sure it’s good news. There are some strange discontinuities going on in these phenomena, at a level we can’t see clearly, and that doesn’t make sense to me. Also, the tiny shapes are not compatible with the big, spread-out shapes–we can never see them both at the same time.

Qbus: But when you apply your theory, it successfully describes our perceptions, doesn’t it?

Bohrus: Yes. I suppose we could just say that the shape world is Complementary.

Qbus: Great term, it has a nice ring to it. What do you think, Socrates?

Socrates: Well, looking at the mathematical structure of this theory, it has more than the 2 dimensions of this wall we’re looking at.

Suacus: So? It works, doesn’t it? Socrates, you are so annoying–always looking for trouble. Always stirring up the pot.

Socrates. Sorry. (Fiddles with chains.)

Same room in the Cave. The next morning.

Pageles: Hey, what were you guys chatting about last night? I dozed off early.

Suacus: You missed something great. Bohrus here developed a theory that successfully describes the behavior of these shapes on the wall. Now, if we want to predict what these shapes are doing, all we have to do is apply his theory. It’s awesome.

Bohrus: Aw Suacus, you’re too kind. I’m still a bit troubled by the perplexities of the theory. The formalism seems to involve invisible entities called Shuanta that seem to transcend the frame of this wall and give rise to mutually incompatible phenomena.

Qbus: But didn’t we decide to call that Complementarity? And isn’t your theory just about our perceptions? Isn’t that the whole lesson of your new theory, in fact? We should enlighten our colleagues with this new insight, and give it a name–maybe a combination of a great logician and a modern art movement, all wrapped up in one cool-sounding term.

Bohrus: Yes of course, you’re right. There is no Shuantum world. There is only my abstract Shuantum-Mechanical description.

Suacus: There ya go. It’s all good.

Pageles: Wow, I missed a lot. You guys are awesome. Count me in.

Bohrus: (Noticing dangling chains next to him) Hey, where’s Socrates?

Later that afternoon.

Socrates (rushing in breathlessly): Hey Bohrus! You know that theory you just came up with? Well I just saw the entities it’s describing! To see them, you have to go outside the Cave! There this bright light, I think it’s what the Mystics refer to as “Consciousness”– and all these huge, multidimensional objects that we can’t see in here. When the light shines on them, we see their shadows, but only one side at a time! That’s why you’re getting this ‘Complementarity’ thing!

Suacus: Goodness, Socrates! Sit down and get comfortable, put your chains back on, and stop talking nonsense.

Bohrus: We just decided there is no Shuantum World, so whatever you think you saw, you’re delusional.

Qbus: Yes, you’ve been talking to too many of those religious charlatans, and they’re messing with your head.

Pageles: We’ve all heard those stories about a strange invisible realm of higher beings and/or ‘consciousness’ that has somehow created all the phenomena we see here. But those are just superstitions and myths created by primitive, unscientific people. The claim that our scientific shadow-studies have anything to do with some domain outside this Cave is false. The notion that what we scientists call “shuanta” has anything to do with anything outside this wall is nonsense. The presentation of Bohrus’ theory side by side, and apparently supportive of, the ideas of the Mystics about a realm beyond the Cave can only be intended to deceive those who might not know any better. Now sit down and shut up, before we feed you hemlock.

*******

Now, of course, Socrates might be wrong. He might be deluded. He may simply have drunk one too many Cave-Cocktails. But the point is that his scientific colleagues cannot use empirical science to make that judgment, one way or the other. And when they try to do that, they misuse their scientific authority by extending it beyond its legitimate purview.

1. The Boundary: Scientific vs. Philosophical or Spiritual Inquiry

It might be said that religion begins where science ends. And it may be turning out that quantum theory has indeed taken us to that point. But first of all, let’s take a quick look at what science is. Science is fundamentally about the observable world — it’s about what we can collectively observe and measure, and about which we have some basis for supposing that we’re all looking at the same thing and seeing it in essentially the same way. Thus, it is fundamentally based on a clear subject-object distinction, where in general many inquiring subjects (theorists and experimenters) are analyzing and measuring the same object. However, as we move to smaller and smaller scales of observation, we find that this is not so easy or straightforward to do; and this is because we run into a fundamental problem with our usual assumption that we can separate our modes of detection (which is required for any observation) from what it is we are trying to observe.

At the quantum level, ‘objects’ behave in what is called a ‘contextual’ manner. That is, they exhibit different kinds of behavior based on how we choose to measure them. This is the well-known ‘wave-particle duality’, in which a quantum object such as an electron will exhibit wavelike interference in an experiment designed to measure its wavelike (extended, non-localized) properties, but it will exhibit particle-like behavior (such a spot on a detection screen) in an experiment designed to localize it. This tells us that the same underlying reality (electron as a quantum system) can give rise to very different phenomena, and that we can never ‘pin down’ that underlying reality to one unambiguous phenomenon. This is not just a pragmatic difficulty: the theoretical description of the underlying reality — the so-called ‘wave function’ that is the solution to the Schrodinger equation of quantum theory — has a mathematical property that literally says that the electron is neither a wave nor a particle, but potentially both.

“Potentially” is the operative word here. Werner Heisenberg, a key pioneer of quantum theory, had this to say about quantum objects described by this ‘wave function’ or ‘probability wave’: “The probability wave …was a quantitative version of the old concept of “potentia” in Aristotelian philosophy. It introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality. [1]

He also put it this way:

Atoms and the elementary particles themselves… form a world of potentialities or possibilities rather than things of the facts.”^[2]

By “things of the facts,” Heisenberg meant the empirically observable world–the world of appearance. Thus, he understood that quantum theory was pointing to something beyond the world of appearance, and in order to do that, he was allowing for the possibility that reality consists of more than the world of appearance. In doing so, he was of course venturing beyond empirical science and into philosophical territory. And of course, beyond the purely philosophical lies the domain of spiritual inquiry.

2. Appearance vs Reality

In the West, the ancient Greek philosopher Plato already had useful insights into this distinction between the observable and the unobservable levels of reality. He said that reality consisted of two different levels: (i) the level of appearance and (ii) the level of fundamental reality–the underlying, hidden reality, which he conceived of as a realm of “Perfect Forms.” His famous allegory of the The Cave was designed to illustrate this distinction. In this story, prisoners are chained deep in a cave, facing a wall on which shadows are cast. The wall is all that they can see, and the phenomena on the wall seem to them to be their entire reality. However, unbeknownst to the prisoners, just outside the mouth of the cave there is a bright light, and people are coming and going between the light and the prisoners, carrying various objects whose shadows are cast on the wall. For Plato, the exterior of the cave, the objects being carried by the people, and the bright light comprise the hidden world of perfect forms (the fundamental reality), while the wall upon which the prisoners gaze is our ordinary world of experience.

We encounter the same contrast between a fundamental, unmanifest reality and an emanated, manifest world of appearance in the Vedic concept of ‘Maya’. While this term has been used in various ways throughout the Easten world, one of its chief uses is to denote the world of appearance as distinct from–and even as obscuring–the underlying, hidden reality. As mythologist Wendy Doniger observes, “to say that the universe is an illusion (māyā) is not to say that it is unreal; it is to say, instead, that it is not what it seems to be, that it is something constantly being made. Māyā not only deceives people about the things they think they know; more basically, it limits their knowledge.”[3] This is very similar to Plato’s allegorical warning that we are deceived when we take the phenomenal ‘shadow play’ as the final story about reality.

The 18th century German philosopher Immanuel Kant also distinguished two fundamental aspects of objects: (1) the object of appearance and (2) the ‘thing-in-itself’, apart from its appearances, which he stated was unknowable. Kant used the Greek term ‘noumenon’ for this second unseen aspect of an object, which translates roughly as ‘object of the mind’. Kant also proposed that there are ‘categories of experience’ that make knowledge of the world of appearance possible. But, unlike Plato and the Eastern philosophers and theologians, Kant assumed that “knowledge” was only about the world of appearance–he held that the world of noumena was unknowable. Kant’s ‘categories of experience’ consisted of concepts like space, time, and causality. But we should take note that Kant proclaimed that Euclidean space was an ‘a priori’ category of understanding, meaning a necessary concept behind any knowable phenomenon—an assertion which has since been decisively falsified by relativity’s non-Euclidean accounts of spacetime. This error illustrates the danger of making categorical assumptions about what principles are required (or conversely, are to be excluded) in order for gaining knowledge about reality, whether at the level of appearance or otherwise.

Twentieth century philosopher Bertrand Russell also had some interesting things to say about the distinction between appearance and reality. In the first chapter of his book, The Problems of Philosophy, he takes us on an exploration of an ordinary table, which leads to an unexpected puzzle. He notes that the table appears differently depending on the conditions under which we observe it, and even to different people who may have different visual capabilities. Finally, he says:

“the real shape[of the table] is not what we see; it is something inferred from what we see. And what we see is constantly changing shape as we move about the room so that here again the senses seem not to give us the truth about the table itself, but only about the appearance of the table. Similar difficulties arise when we consider the sense of touch. It is true that the table always gives us a sensation of hardness, and we feel that it resists pressure. But the sensation we obtain depends upon how hard we press the table, and also upon what part of the body we press with. Thus the various sensations due to various pressures or various parts of the body cannot be supposed to reveal directly any definite property of the table, but at most to be signs of some property which perhaps causes all the sensations, which is not actually apparent in any of them. … it becomes evident that the real table, if there is one, is not the same as what we immediately experience by site or touch or hearing. The real table, if there is one, is not immediately known to us at all but must be an inference from what is immediately known. Thus, two very difficult questions at once arise: (i) is there a real table at all? (ii) If so, what sort of object can it be?”[4]

Recall that this was the same contrast that Plato highlighted in his allegory of The Cave. He noted that the world of appearance is quite different from the real world or the underlying reality–just as, according to the concept of maya, reality is not what it appears to be. Bertrand Russell laid out quite effectively how hard it is to actually know anything about the underlying reality: something as trivial and obvious as a table has been analyzed to the point where it seems to have almost disappeared; we are having trouble getting at what the real table is, or even whether there really is one at all.

This is a notorious problem in philosophy, and there are various approaches to solving this problem and perhaps getting around it. There are a great many modern philosophers who feel that they may have resolved this problem by revising the whole way that we approach the question of how we know about the “real table” that we think is out there. But the bottom line is that we have to take into account that what is directly accessible to us, especially as scientists, is the world of appearance. Western empirical science is first and foremost about the world of appearance by definition, because it’s about what we can observe. In that respect, it must be limited to the ‘Cave.’ It is very hard to justify, within empirical science, saying anything at all about the reality that underlies the appearances.

On the other hand, it is Western science that came up with quantum theory, which ironically seems to point to a domain outside the Cave, in that the mathematical properties of the theory dictate that what it describes is not something that can be contained within the Cave! This is the fundamental source of the controversy over the interpretation of quantum theory–it is why many practitioners of quantum theory wish to deny that the theory actually describes anything real. To do so would be to admit that ‘reality’ must go beyond the Cave-world of appearance.

Thus, while science as a system of knowledge is very rigorous and capable of providing us with well corroborated theories, when we want to talk about those theories as providing facts, we need to take into account that what we take as facts have to be limited to the world of appearance. When we consider using science to talk about an underlying reality, we enter into some very difficult and puzzling issues –and much attendant controversy–because we are faced with a choice: either (i) to acknowledge that science cannot answer all our questions about reality, or (ii) if we want to insist that it does, to make a philosophical (as opposed to scientific!) choice that all there is to reality is the world of appearance. The reason that (ii) cannot be a purely scientific choice is that empirical science, being limited to the world of appearance, cannot itself determine whether or not there is an aspect of reality beyond the world of appearance! If we opt for (i), as scientists and as philosophers of science, we celebrate the power and utility of science, but we acknowledge its limitations as well. In the next installment, we’ll look more closely at the pitfalls of opting for (ii), especially without being aware that doing so goes well beyond science.

[1] Heisenberg, W. (2007). Physics and Philosophy. New York: HarperCollins.

[2] Ibid.

[3] Wendy Doniger O’Flaherty (1986). Dreams, Illusion, and Other Realities. University of Chicago Press, p. 119.

[4] Russell, B. (1912). The Problems of Philosophy. Public Domain.

[5] As quoted in Jammer, M. (1993). Concepts of Space: the History of Theories of Space in Physics. New York: Dover Books. p. 189.

“Now in the further development of science, we want more than just a formula. First we have an observation, then we have numbers that we measure, then we have a law which summarizes all the numbers. But the real glory of science is that we can find a way of thinking such that the law is evident.” -Richard Feynman

Quantum theory tells us that light is somehow both a wave and a particle. It behaves like a particle pursuing an ordinary ray-like path in some situations; but in others, its wave nature cannot be ignored. In this post, we revisit Feynman’s delightful account of the principle of least action, which can help to explain the propagation of light under all these changing circumstances. He starts by considering the principle of least time (a simplified form of the principle of least action), about which he says:

“The idea of causality, that it goes from one point to another, and another, and so on, is easy to understand. But the principle of least time is a completely different philosophical principle about the way nature works. Instead of saying it is a causal thing, that when we do one thing, something else happens, and so on, it says this: we set up the situation, and light decides which is the shortest time, or the extreme one, and chooses that path. But what does it do, how does it find out? Does it smell the nearby paths, and check them against each other? The answer is, yes, it does, in a way.”

Feynman liked to picture light as always being a particle, and came up with a way to explain its wavelike behavior based on the particle’s ability to explore all possible paths in spacetime. This is what he meant by his metaphor of light ‘smelling’ its way from a source to a final destination. He thought of a particle of light starting out from its source and exploring all the infinite possible routes to get to a final destination, judging the best route by the way the neighboring routes compare with it in terms of the time they would take. If those neighboring routes take a very different time from the route being considered, that route gets rejected; but if the neighboring routes take about the same time, that route is chosen.

Clearly this is a complicated and sophisticated process! If we think of light as a little particle doing this route comparison for every possible route, we might wonder how light ever manages to get anywhere!

A photon examining and comparing all possible routes with one another.

It turns out that if we just stick to the wave picture, we can see quite readily how the behavior of light emerges naturally. But one might ask, what happened to the particle nature of light? We’ll see that it emerges after the wave has done its exploratory work.

Below is a slightly modified version of Feynman’s picture of a wave of light encountering an opening in a screen (notice that even Feynman, who thought of light as a particle, had to include their wave nature!). Two different possible sizes of the opening are shown; the dashed lines show the initially large opening closing down to just a tiny pinhole. For the wider opening, a lot of the initial wave gets through, and is relatively undisturbed by its passage through the hole, so it continues to propagate in the original direction (shown in blue wavefronts and the blue arrow). Most of the light is received at point A in a straight, ‘ray-like’ path from the source.

However, for the tiny opening, the wave is greatly disturbed by its passage, and spreads out as it exits from the hole (this is called ‘diffraction’). This situation is shown in red. We see this sort of thing all the time with ordinary waves, such as water waves. For this case, the light has a much greater chance of ending up at B or C, which was very unlikely with the wider slit.

In the Transactional Interpretation (TI), all quantum objects such as photons are fundamentally wavelike. They do all their basic ‘exploring’ as waves , and it’s only in the very final stage that a particle-like behavior emerges. In TI, a photon begins life as an ‘offer wave’ (OW for short) emanating from an emitter. But at subtler levels (the relativistic level), it turns out that an OW is only emitted if it also gets responses — ‘confirmation waves’ from systems (such as atoms) that are eligible to absorb its energy. The interaction between an emitting atom and one or more (usually many) absorbing atoms is a kind of mutual negotiation, and both are necessary to get the process started. Once the process starts, the OW still has to decide which of many responding atoms it will choose for its energy deposit. All of this goes on in the background, beneath or beyond the spacetime theater. It’s akin to actors taking their places before a scene is filmed–only the final filmed scene is the spacetime process. But in this case, many actors are called but in the end only 2 are chosen: the emitter and ‘winning’ absorber. Then the filming proceeds — and that is the actual process that occurs in spacetime. The selection of one absorber and the delivery of a chunk of energy is the point where the discrete, particle-like aspect enters. The delivered chunk of energy is the “particle” or quantum.

All stages except the final choosing of the winning absorber are carried out with the wavelike aspect–this is the De Broglie wave, named after the French physicist Louis de Broglie, who first proposed that not only light, but material particles like electrons have a wavelike aspect as well.

So in the TI picture, we don’t have a photon of light having to examine all possible paths. We just have a wave undergoing natural wavelike interference. It is that interference that becomes part of the negotiation between the emitter and all its potential absorbers. Some potentially absorbing atoms may not respond at all, if the offered wave undergoes completely destructive interference before it reaches them. On the other hand, the wave can constructively interfere and provide a large OW component that elicits a correspondingly large CW response from potential absorbers that it reaches. Feynman’s ‘sum over paths’ boils down to a description of the behavior of the interfering OW. The particle of light–the photon–emerges only at the final stage, when one of the responding absorbers ‘wins’ the contest and absorbs a quantum of electromagnetic energy–a photon.

[Note: this is an adapted excerpt from the introductory chapter to a collected volume, Quantum Structural Studies, forthcoming from World Scientific (eds. R.E. Kastner, J. Jeknic-Dugic, and G. Jaroszkiewicz.]

The idea that unitary-only dynamics can lead naturally to preferred observables, such that decoherence suffices to explain emergence of classical phenomena (e.g., Zurek 2003) has been shown in the peer-reviewed literature to be problematic. However, claims continue to be made that this approach, also known as ‘Quantum Darwinism,’ is the correct way to understand classical emergence.

The problem of basis ambiguity in the unitary-only theory is laid out particularly clearly by Bub, Clifton and Monton (1996), and the difficulty highlighted by them is not resolved through decoherence arguments alone. This is because decoherence is  relational rather than absolute (Dugic and Jeknic-Dugic 2012; Zanardi et al 2004). In order to get off the ground with a particular structure, “Quantum Darwinism”-type arguments depend on assuming special initial conditions of separable, localizable degrees of freedom, along with suitable interaction Hamiltonians, which amount to “seeds” of classicality from the outset.

Under these circumstances, the purported explanation of classical emergence becomes
circular (Kastner, 2014a, 2015). But circularity is not the only problem with the decoherence-based attempt to explain the emergence of classicality. In what follows we examine the logical structure of the argument and find a further, serious flaw: affirming the consequent.

2. The logical flaws of “Quantum Darwinism”

The structure of the Quantum Darwinism argument is as follows:
If
1. the quantum dynamics is unitary-only, and
if
2. the universe has initially separable, localizable degrees of freedom such as distinguishable atoms, and
if
3. those degrees of freedom interact by Hamiltonians that do not re-entangle them,
then
4. classicality emerges.

For decoherence to account for the emergence of classicality under the assumption of unitary-only (U-O) evolution (approximately and only in a “FAPP” sense, see below), all three premises must hold. However, classicality is implicitly contained in 2 and 3 through the partitioning of the universal degrees of freedom into separable, localized substructures interacting via Hamiltonians that do not re-entangle them, so (given U-O) one has to put in classicality to get classicality out. Premises 2 and 3 are special initial conditions on the early universe that may not hold–certainly they are not the most general case for an initially quantum universe. Yet it seems common for researchers assuming U-O to assert that 2 and 3 also must hold without question. This actually amounts to the fallacy of affirming the consequent, as follows: one observes that we have an apparently classical world (affirm 4), and then one asserts that 1, 2 and 3 therefore must hold.

The insistence on 2 appears, for example, in Wallace’s invocation of “additional structure on the Hilbert Space” as ostensibly part of the basic formalism (Wallace 2012, p. 14-15). Such additional structure–preferred sets of basis vectors and/or a particular decomposition of the Hilbert space–is imposed when quantum theory is applied to specific situations in the laboratory. However, what we observe in the laboratory is the already-emergent classical world, in which classical physics describes our macroscopic measuring instruments and quantum physics is applied only to prepared quantum systems that are not already entangled with other (environmental) degrees of freedom.

If the task is to explain how we got to this empirical situation from an initially quantum-only universe, then clearly we cannot assume what we are trying to explain; i.e., that the universe began with quasi-localized quantum systems distinguishable from each other and their environment, as it appears to us today. Yet Wallace includes this auxiliary condition imposing structural separability under a section entitled “The Bare Formalism” (by which he means U-O), despite noting that we assign the relevant Hilbert space structures “in practice” to empirical laboratory situations. The inclusion of this sort of auxiliary condition in the “bare formalism” cannot be legitimate, since such imposed structures are part of the application of the theory to a particular empirical situation. They thus constitute contingent information, and are therefore not aspects of the “bare formalism,” any more than, for example, field boundary conditions are part of the bare theory of electromagnetism.

These separability conditions are auxiliary hypotheses to which we cannot help ourselves, especially since the most general state of an early quantum universe is not one that comes with preferred basis vectors and/or distinguishable degrees of freedom. Thus, the addition of this condition amounts to asserting (2), and becomes (at best) circular reasoning, or (at worst) outright affirming of the consequent, illicitly propping up the claim that quasi-classical world “branches” naturally appear in an Everettian (unitary-only) picture.

Now, to be charitable: perhaps unitary-only theorists are tacitly assuming that (1) is not subject to question; i.e. they  take it as a “given.” If one presumes the truth of (1) in this way, then (2) and (3) seem required in order to arrive at our current apparently classical world. If (1) were really known to be true, the logical structure of the argument would be: “2 and 3 if and only if 4”. So, rather than reject the argument based on its circularity, such researchers seem to assume that the consequent is evidence for the truth of premises 2 and 3 (i.e., 2 and 3 together are seen as the only way that we could have arrived at the classical macro-phenomena we now experience). The possibility that the dynamics may not be wholly unitary–the falsity of the unitary-only premise (1)–does not seem to be considered. However, the need to use a circular argument in order to preserve the claims of Quantum Darwinism should prudently be taken as an indication that the U-O assumption (1) may well be false, and that non-unitary collapse is worth exploring for a non-circular account of how classically well-defined structures arise in a world described fundamentally by quantum theory. (Such an account is proposed in Kastner (2012) and (2014b). In that account (‘possibilist transactional interpretation’ or PTI), decoherence can of course occur under circumstances discussed in Zurek (2003), as a deductive consequence of quantum theory under certain specified conditions; but decoherence alone is neither necessary nor sufficient as an explanation for everyday classical phenomena such as the observed determinacy of macroscopic objects. Decoherence is not necessary because classical emergence can arise through a specific collapse process in PTI, and decoherence is not sufficient because it does not solve the measurement problem (cf. Bub 1997, p. 231).)

3. Conclusion.

Everettian unitary-only quantum theory seems to have become so “mainstream” that in many quarters it now appears to be considered the “standard” theory, replacing the theory consisting of Schrodinger unitary evolution plus von Neumann non-unitary measurement transition. Yet the only way to arrive at the world of classical phenomena we experience in the unitary-only theory is to assume classicality at the outset–and even this is only approximate and “FAPP,” since it fails to solve the measurement problem, as noted in Bub 1997, Section 8.2. The “decoherence” process as invoked in service of “Quantum Darwinism” is at best circular and at worst amounts to the logical fallacy of affirming the consequent. The alleged utility of decoherence is greatly overstated and illusory. It is time to consider the possibility that Everett might have been wrong.

References

Bub J, Clifton R, Monton B, 1998, The Bare Theory Has No Clothes.

In {\bf Quantum Measurement: Beyond Paradox}, eds. Healey R A, Hellman
G, {\bf Minnesota Studies in the Philosophy of Science 17}, 32-51.
Dugi\’ c M., Jekni\’ c-Dugi\’ c J., 2012, Parallel decoherence in composite quantum
systems, Pramana {\bf 79}, 199

Dugi\’ c M., Arsenijevi\’ c M., Jekni\’ c-Dugi\’ c J., 2013,
Quantum correlations relativity, {\bf Sci. China Phys., Mech. Astron.
56}, 732
Jekni\’ c-Dugi\’ c J.. Dugi\’ c M., Francom A., 2014, Quantum
Structures of a Model-Universe: Questioning the Everett
Interpretation of Quantum Mechanics, {\bf Int. J. Theor. Phys.
53}, 169

Kastner, R.E., 2012. {\bf The Transactional Interpretation of Quantum Mechanics: The Reality of Possibillty}.
Cambridge: Cambridge University Press.

Kastner R. E., 2014a, Einselection of pointer observables: The new
H-theorem?, {\bf Stud. Hist. Phil. Mod. Phys. 48}, 56

Kastner R. E., 2014b, The Emergence of Spacetime: Transactions and Causal Sets,
forthcoming in {\bf Beyond Peaceful Coexistence}, I, Licata, ed.; Preprint version http://arxiv.org/pdf/1411.2072v1.pdf.

Kastner R. E., 2015, Classical selection and quantum Darwinism,
{\bf Phys. Today 68}, 8
Wallace, D., 2012, {\bf The Emergent Multiverse: Quantum Theory
according to the Everett Interpretation}. Oxford University Press,
Oxford
Zanardi P., Lidar D. A., Lloyd S., 2004, Quantum Tensor Product
Structures are Observable Induced, {\bf Phys. Rev. Lett. 92},
060402

Zurek W. H., 2003, Decoherence, einselection, and the quantum
origins of the classical, {\bf Rev. Mod. Phys. 73}, 715

I recently was reminded of the somewhat archaic term ‘preternatural’ while watching the classic 1963 horror flick “The Haunting.” In this amazing film, a scientist interested in occult matters (including, especially, ghosts) decides to investigate Hill House, a nearly century-old mansion notorious for being cursed with untimely deaths and considered as undeniably haunted. He and several other hand-picked personnel take up residence in the house, and become subject to various terrifying experiences (I won’t include any spoilers here).

The remarkable feature of the film, from my standpoint as a philosopher of science, was the sophistication of the film’s treatment of scientific inquiry through the persona of the ‘ghost-hunting’ scientist. In his attempts to assuage their fears (on the one hand) or dislodge their skepticism (on the other), he engages his fellow residents/subjects in conversation about his goals and methods. He tells them that he is convinced that there is an understandable explanation behind the phenomena, even though that explanation might involve forces or entities previously unknown. These sorts of phenomena he refers to as preternatural. He notes that in ancient times, magnetic phenomena were viewed suspiciously in this way: they were either feared or denied, since no “natural” explanation was known for them. Yet eventually, science was able to account for magnetic phenomena in terms of the notion of a force that acts according to specific laws, and now it is viewed as perfectly “natural.” So the preternatural, in this context, means something at first disturbing and incomprehensible that nevertheless may become familiar and comprehensible once we better understand it through an expanded conceptual awareness. In that sense, the preternatural is distinguished from the supernatural (which means completely outside the domain of natural scientific explanation).

We have been face to face with a very similar situation ever since the discovery of quantum phenomena. Einstein famously called the nonlocal features of quantum entanglement “spooky action at a distance.”  Just as ancient people faced with magnetic phenomena often denied them because they had no “natural” explanation, many researchers want to deny that such nonlocal phenomena reflect anything that really exists. This is because such phenomena don’t have what many researchers can accept as a natural explanation, where what is currently viewed as “natural” is referred to as “local realism.”

Local realism boils down to the idea that all influences are conveyed from one well-localized object to another on a well-defined spacetime trajectory (like a baseball going from the pitcher to the catcher). In fact, progress was made in explaining magnetic (and also electric) phenomena when physicists could explain those in terms of what is called a ‘field of force’. This classical notion of a field of force is a ‘local realistic’ one, in that it accounts for the motions of objects under the influence of these forces in a local, spacetime-connected way: the force is carried by a kind of ‘bucket brigade’ through space and time at no more than the speed of light.

However, it is now well known (through Bell’s theorem) that quantum influences cannot be explained through this bucket brigate picture of classical fields. The influence due to a measurement on one member of an entangled pair of quanta is communicated apparently instantaneously  to the other, no matter how far away it is.

Many researchers, faced with these results, throw up their hands and say that there can be no natural explanation for the phenomena in terms of real things; that no realistic explanation is possible. Since no self-respecting scientist will dabble in the supernatural, such researchers turn to antirealism: they deny that there is anything physically real beneath these phenomena. In doing so, they assume that ‘natural’ or ‘realistic’ can only mean a ‘bucket brigade’ spacetime process, as described above for classical fields. But perhaps there is an alternative: recognize that these phenomena need not be viewed suspiciously as supernatural, but that they are merely preternatural; and that in order to understand them, we must expand our viewpoint concerning what counts as ‘natural’.

This expansion consists in the idea that there may be more to reality than spacetime, and that quantum theory is what describes that subtler, unseen reality. In this picture, quantum processes underlying the nonlocal entanglement phenomena (and other strange phenomena such as ‘collapse of the wavefunction‘) take place in a realm beneath and beyond the spacetime realm. In fact, collapse is what gives rise to spacetime events. For more on this expanded view of reality, see my new book:

It might be useful to tell students that multiplication can be seen as repeated addition under certain circumstances. But docking a student half credit because he/she used commutativity when that was allegedly not permitted–because not specifically taught yet–is fallacious. You can see why if you simply look at a picture of repeated addition for the stated problem (5X3=…), say using stars:

To get the so-called ‘correct solution’ you repeat the addition of the rows, and to get the so-called ‘wrong solution’ you repeat the addition of the columns. Docking half credit amounted to telling the student they could not add the columns. Unfortunately many children in this position simply assume, in total bewilderment, that math is some inscrutable strange mystical language that they will never hope to figure out.

The student was absolutely correct in his/her answer, whether or not anyone taught that student the concept of commutativity. Prohibiting the use of commutativity in this solution amounts to discounting and even prohibiting the picturing of multiplication, whose far more comprehensive and direct meaning is that of area. The teaching of multiplication as repeated addition dependent on the order in which numerals are written down on paper shrinks–and distorts–the concept of multiplication down to a shadow of what it really is. All this confusion could be avoided if students are encouraged to picture math concepts instead of thinking of them as a matter of reading symbols from left to right and following a ‘strategy’ (one that doesn’t work when dealing with concepts like the area of a circle which cannot be solved by repeated addition anyway).

Furthermore, clearly the intent of the problem was for the student to literally write down the meaning of “5X3,” which in the context of repeated addition was assumed to be “the number 3 taken 5 times”. But this is just an arbitrary linguistic convention. The expression “5X3” could also linguistically mean “the number 5 taken 3 times”. Indeed many of us, when ordering an item, list the item on the left and then put a numeral in a box to the right saying how many of that item we want! So in that case the problem is clearly saying ‘we want 3 fives’. This is perfectly natural. So it is not at all clear that the intended grading of this problem is even assessing use of commutativity, as claimed in many defenses of the grading. The student could simply have a different linguistic interpretation of the expression. And it’s completely appropriate. In my opinion, this student and all other students marked wrong on this problem are owed an apology. And a different way of teaching multiplication that shows what it is conceptually rather than reducing it to linguistically arbitrary ‘strategies’ that don’t necessarily work for all kind of numbers (e.g., irrational or transcendental numbers).

And if you’re worried about non-commutativity, I’m sure that students who are not totally discouraged by repeated addition conventions will be able to deal with it when they get to quantum mechanics and/or non-Abelian group theory. There are pictures for that too. Here’s one for non-commuting operators in quantum theory. There’s a big difference between (1) first opening the window and then sticking your head out; and (2) first sticking your head out and then opening the window.

There has been much angst in the cybersphere recently about purported hijackings of solid, rational physical theory in service of ‘unprincipled New Age fantasies’ about ‘Consciousness’ being implied by quantum theory. The purpose of this post is to set the record straight about where these allegedly  ‘Crazy’, ‘Wrong’ ideas came from: distinguished pioneering quantum physicists. In fact, this is all ancient history for students of foundations of physics. It can be found in the comprehensive historical record of the pioneering discussions of the implications of quantum theory, Quantum Theory and Measurement (a collection of essays edited by Wojciech Zurek and Nobel Laureate John A. Wheeler), which I’ll abbreviate here as QTM.

Before I get into that, however, a caveat: my proposed interpretation of quantum theory, the ‘Possibilist Transactional Interpretation’ (PTI), (account for the general reader here) provides an observer-independent account of quantum measurement. PTI accounts for the measurement process without any necessary reference to an ‘outside conscious observer.‘ (This was of course also true of the original Transactional Interpretation (TI) of John Cramer; my work is just an extension of TI.) The issue of how to account for conscious experience then returns to the realm of metaphysics (and philosophy of mind and  psychology) where it belongs. In saying that, however, I do not disparage metaphysics; I recognize it as a legitimate realm of inquiry. And quantum theory can be interpreted as having some bearing on such questions, even though consciousness is not an absolute requirement for describing the process of measurement itself, as shown by the TI formulation which takes absorption into account.

Now let’s look at the history of the development of quantum mechanics, which was thoroughly saturated with discussions of consciousness and the mind. First,  celebrated mathematical genius and quantum theory pioneer John von Neumann stated in 1955 that “N. Bohr, Naturwiss. 17 (1929)…was the first to point out that the dual description…necessitated by the formalism of the quantum mechanical description of nature is fullly justified by the physical nature of things [and] that it may be connected with the principle of psycho-physical parallelism.” (Footnote 207, QTM)

This “psycho-physical parallelism” is a purely metaphysical doctrine saying that a physical process in the body is accompanied by a subjective psychological experience in the mind without any causal connection between them. Does this sound ‘New Age-y’ to you? It does to me. Yet Von Neumann not only reports Bohr’s use of this term but explicitly invokes it in his account of ‘measurement’ in quantum theory:

“..we must always divide the world into two parts, the one being the observed system, the other the observer. In the former, we can follow up all the physical processes…arbitrarily precisely. In the latter. this is meaningless. ..that this boundary can be pushed arbitrarily deeply into the interior of the body of the observer is the content of the principle of the psycho-physical parallelism.”  Von Neumann goes on to refer to the ‘ego’ of the observer as that which experiences a single outcome of the measurement, even though the physical system is described only be a set of outcomes. Connecting the two is the mysterious ‘collapse’, for which Von Neumann gives a formal representation but which he explicitly says lies outside any physically describable system.

So there you have it: the ‘ego’ of the conscious observer, in a process of ‘psycho-physical parallelism’, is seen by Quantum Physics Guru John Von Neumann as what leads to ‘collapse of the wavefunction’. This identification of the mind as a purportedly essential component of quantum phenomenology did not come from ‘New Age charlatans’; it came from the original quantum physicists.

Von Neumann was certainly not the only one. Our next visit in the trip down Quantum Memory Lane is with Nobel Laureate John Wheeler, who asserted: “no phenomenon is a real phenomenon until it is an observed phenomenon.” (“Law Without Law,” QTM, p. 183)  Wheeler coined the term ‘Participatory Anthropic Principle” (PAP), the notion that the universe is brought into existence by the participation of observers. Now, the article linked above in connection with PAP notes that Wheeler left some ambiguity about what constitutes an ‘observer’ and whether consciousness was necessary for wave function ‘collapse’. But it  also notes that Stanford University physicist Andrei Linde answers that question–whether consciousness is required–with a decisive ‘yes’. This is no so-called “New Age quack”. It is a Stanford physics professor speaking. In 2002.

Nobel Laureate Eugene Wigner also embraced consciousness as a supposedly inescapable implication of quantum theory:

“When the province of physical theory was extended to encompass microscopic phenomena, through the creation of quantum mechanics, the concept of consciousness came to the fore again: it was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to the consciousness. All that quantum mechanics purports to provide are probability connections between subsequent impressions (also called “apperceptions”) of the consciousness, and even though the dividing line between the observer, whose consciousness is being affected, and the observed physical object can be shifted towards the one or the other to a considerable degree, it cannot be eliminated. It may be premature to believe that the present philosophy of quantum mechanics will remain a permanent feature of future physical theories; it will remain remarkable, in whatever way our future concepts may develop, that the very study of the external world led to the conclusion that the content of the consciousness is an ultimate reality”  (Wigner, “Remarks on the Mind-Body Question,” Symmetries and Reflections. Indiana University Press, Bloomington, Indiana, 1967, pp.171-184.)(My emphasis)

Of course, as noted above, John Cramer and I disagree with this characterization, since TI shows that once the physical process of absorption is taken into account, there is no ‘shifty split’ of the line from physical system to consciousness of an observer. But the question as to why and how we are conscious beings is an important one that should not be disparaged, even though purely physicalist theories and approaches have a hard time accounting for it. Recent attempts to dismiss ‘metaphysics’ and ‘philosophy’ are unwarranted and unworthy of the quest for understanding of ourselves and our place in the universe. They are also basically just a repeat of the mid-20th century ‘positivist’ movement, which tried to argue that any ‘nonverifiable’ statement was ‘meaningless’. That turned out to be a fruitless and unsupportable misconception that was disposed of not long after it arose. A nice discussion of the obsoleteness of this anti-metaphysics view is given here. Responsible scientists now acknowledge that all observation is ‘laden’ with theoretical constructs including metaphysical and epistemological assumptions, and that there is no such thing as ‘objective data’ that is uncolored by such assumptions. It is simply naive to try to portray science as free of ‘philosophical musings’.

In conclusion, I’ve attempted to point out that so-called  ‘New Age Quacks’ came by their beliefs that quantum theory involves consciousness honestly: they were told this by the founders of quantum theory and they continue to hear this from highly credentialed quantum physicists. I happen to disagree that ‘consciousness’ is required to account for ‘collapse–TI shows why this is unnecessary (and see my new book for a detailed account for the general reader of why this is so). But the questions surrounding the nature of consciousness and mental processes are important ones. They should not be disparaged just because science (understood in physicalist, mechanistic terms) does not seem to have an answer.

Dear Dr. Harris:

At one point in your comments to Dr. Chopra (in “The Future of God” debate), you stated that one will never see a theoretical physicist make a categorical, dogmatic assertion. But I have often seen physicists (and philosophers of physics) do just that. One example is the often-dogmatic assertion that ‘physics implies a block world’ (i.e. that the future exists just as the past and present), when in fact physical theory does not force that conclusion (see, e.g., Raphael Sorkin’s “Relativity does not imply that the future already exists”)[1].

A famous historical example of a baldly dogmatic statement by a theoretical physicist is Niels Bohr’s categorical assertion: “There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature…” (as told to Aage Petersen; my emphasis)[2]. Now, Bohr had certainly done some careful philosophical investigation into quantum theory, and there are many subtleties to his thought and much that can be debated about his philosophical approach. But his explicitly dogmatic assertion about what constitutes ‘wrong thinking’ is neither scientifically nor philosophically justified. It presumes certain metaphysical and epistemological tenets that can be, and have been, rationally questioned. For example, Bohr presumed that everything about the physical world must be describable in classical terms. But in fact one can take quantum theory’s mathematical formalism as providing real information about the structure of the quantum world, even though we cannot capture that structure in the usual classical language of ordinary experience.

So unfortunately scientific researchers often deal with unresolved interpretational aspects of physical theory by lapsing into dogma. Contra Bohr, there certainly can be a quantum world, and physical theory certainly can be saying something about its nature, even if that nature is non-classical. Bohr’s assertion presupposes a conceptual and linguistic framework that is not essential or necessarily appropriate to the task at hand. In more colloquial terms, he was thinking inside a particular kind of box, and his dogmatic pronouncement sought to impose that box on all other researchers. This is why the Irish physicist John Bell railed against Bohr’s unjustified circumscription on discourse, writing a now-famous paper entitled “Speakable and Unspeakable in Quantum Mechanics”.

Of course, quantum theory certainly presents science with a wholly new kind of interpretational dilemma, since its formalism inhabits a domain mathematically larger than that of the empirical (3+1 spacetime) realm that is the traditional domain of physical science. My own proposed resolution to this dilemma involves a rationally grounded step beyond the empirical realm. That is, I offer the view that QM is a physical theory whose referent is a kind of reality that cannot be empirically observed. While this may seem radical, it should be kept in mind that Ludwig Boltzmann took a similar step when he proposed unobservable ‘atoms’ whose behavior gave rise to the macroscopic laws of thermodynamics. Though derided by his contemporaries (in particular Ernst Mach), Boltzmann’s postulation of unobservable entities turned out to be the fruitful way to go. (While we think we ‘observe’ atoms now, we actually just indirectly image them; those images are the results of particular kinds of interactions with our macroscopic instruments.)

The point here is that not all of reality describable by physical theory is necessarily contained within the empirical realm, even though physical theories can only be tested by checking against empirical data. There is no necessary logical incompatibility between these two circumstances. Indeed there are often good theoretical reasons (such as the predictive successes of theories based on unobservables) to allow for the existence of unobservables.

This naturally brings us to the topic of spirituality, which was the main subject of the debate. This feature of human experience (that is, at least of many humans) was unfortunately trivialized in the discussion by an assertion that modern monotheistic schools of thought are substantially the same as ancient worship of polytheistic gods. But in fact there are deep and significant differences between, say, Christian monotheism and worship of the Greek pantheon. I don’t think one will find a Zeus-worshiper saying things like “Show by your good life that your works are done with gentleness born of wisdom…the wisdom from above is first pure, then peaceable, gentle, willing to yield, full of mercy and good fruits, without a trace of partiality or hypocrisy…” (James 3:13, 17; New Testament)

In any case, it is perfectly possible that spiritual experience–which is primarily subjective and inward in nature–is simply a different mode of knowledge and discovery complementary to the scientific mode, the latter being primarily intersubjective and based on outer sensory experience.[3] Thus, spiritual experience might just be another way that many people ‘intuit’ the existence of sub-empirical aspects of the world. This is why it could make sense for the hermit in the cave to have an inner experience of an ‘unseen’ aspect to reality that could just possibly be the same reality described by quantum theory. Note that this suggestion is not dogma, just an offer of a possible connection between science and spirituality. In fact other researchers have suggested such a connection–e.g., Fritjof Capra (The Tao of Physics) and Gary Zukav (The Dancing Wu Li Masters). That is why I found it unfortunate to see such a schism between religion and science evidenced in the Caltech discussion, when in fact there may be some common ground between these different ways of knowing.

You and Dr. Shermer are right that organized religion has been a cause of much evil and suffering–and in fact that seemed to be your primary concern about religion in the debate. But all modes of knowledge can be abused for destructive purposes. Many wars are fought not over religion but to serve geopolitical and territorial goals, with religious or other lofty ideological principles often being used as a pretext for conquest and domination. Many scientific discoveries were ‘spinoffs’ of inquiries into how to be more effective in war (for example, the kinematics of projectile motion was a byproduct of efforts to improve cannonball aim).

Finally, to return to the concern that opened this letter: the temptation to overstate one’s case and be dogmatic is not confined to those professing claims about spiritual knowledge. It is an ever-present trap for all researchers to fall into, and those in the ‘rational’ knowledge traditions, including the sciences, are not immune[4].

Respectfully,

Ruth Kastner

P.S. Regarding free will, which you have apparently ruled out: it is certainly not a foregone conclusion that physical science disallows robust free will. That assertion, which is well on its way to becoming a dogma itself, is based either on not taking quantum theory into account or on a particular use of the quantum probability law that arguably is not justified. See, for example my earlier post:

https://transactionalinterpretation.org/2015/02/14/free-will-why-we-should-be-skeptical-of-the-skeptics/

[1] http://link.springer.com/chapter/10.1007/978-1-4020-6318-3_9

[2] The Genius of Science: A Portrait Gallery (2000) by Abraham Pais, p. 24

[3]I use the word ‘intersubjective’ rather than ‘objective’ here, because no individual scientist can get outside his or her perceptions to perceive an independently existing reality, but must rely on corroborations between many individual reports. If this seems like nitpicking, one might wish to read Chapter 1 of Bertrand Russell’s The Problems of Philosophy, which points out in graphic detail how no two people ever really see the same table, and moreover that it is a highly nontrivial question as to whether there even is a ‘real,’ objective table independently of observation.

[4] If I’m ever found to have committed such a lapse, I will readily acknowledge and correct it.

I recently had a conversation with Deepak Chopra about the ideas in my new book, Understanding Our Unseen Reality: Solving Quantum Riddles.

A preview is here: https://www.youtube.com/watch?v=GLj3hWNGkYQ&feature=youtu.be

Full interview is here:

https://app.curiositystream.com/#/collection/162/916

The idea of ‘weak measurements’ has been much discussed recently in the popular science presses as well as in physics journals. This post aims to demystify some of the claims made about quantum systems based on weak measurements.

As illustration of the basic idea of weak measurement, consider the following analogy. A quantum shoe factory makes 2 models of shoe: a casual shoe ‘C’ and a dress shoe ‘D’. But since these are quantum shoes, the factory churns them out in a superposition of both models–call that ‘B.’ (For physicists, B is analogous to ‘spin up along x’, and C and D are spin up and down along z, respectively). It is only when Fred, the shoe checker, inspects each shoe that their nature as C or D is clearly ‘collapsed’ and thereby established. At this point, Fred places each kind of shoe in its respective bin for shipment to two different stores–one that only orders C and the other only orders D. (This is analogous to a sharp measurement that destroys the interference patern in the electron two-slit experiment.)

Now suppose it is Saturday morning, and Fred had one too many Happy Hour drinks the night before. As he ‘measures’ each shoe in its B state, his sloppiness results in some C shoes erroneously being placed in the D bin, and vice versa. If enough of these errors are made, such that Fred is just as likely to place a shoe in the wrong bin as he is to put it in the right bin, then each bin contains equal amounts of C and D, and the shoes have just had their initial combined state B confirmed. (This is analogous to having retained the interference pattern in the electron two-slit experiment.)

Suppose that hungover Fred has to sort 100 shoes. He has just enough of his faculties left to put ever-so-slightly more shoes in the correct bin than in the incorrect bin. This is the basic  ‘weak measurement’. He has almost retained the original shoe state, but not quite–the shoes in each box have gotten a bit ’tilted’ more toward C or D than they originally were.That is, each in the C bin is slightly more likely to be found in the state C than in the state D, and vice versa.

Now, to make contact with some of the claims in the literature concerning ‘weak measurements’, we have to add one more step: a follow-up careful (‘sharp’) measurement of every shoe in each of the bins. (For physicists, this is the post-selection measurement of z spin). Suppose the person carrying out this measurement is Gretchen, who unlike her co-worker Fred, did not attend Happy Hour the previous evening. Gretchen first takes bin C, and with coffee in hand, carefully measures each shoe in the box. She finds that (say) 52 of the shoes have come out (correctly) C and 48 of the shoes have come out (incorrectly) D. Then she takes the other bin  D, and finds that (say) 53 of the shoes have come out (correctly) D and 47 have come out (incorrectly) C.  At this point, only Gretchen knows and has written down which bin each shoe came from and whether Fred correctly sorted it or not. But the probability of a shoe’s having been placed in Fred’s bin C is slightly higher if it was found by Gretchen to be C.

Now, some researchers have made the following claim based on this procedure: because of Gretchen’s final measurement, each shoe somehow ‘knows’ before Fred’s sloppy sorting which of his bins it’s going to end up in. That is, Gretchen’s measurement is claimed to act rather like Merlin the Magician, who travels from the future into the past and helps beings to fulfill their destiny. The idea is that each shoe is retroactiviely steered by Gretchen’s final measurement toward its respective bin placement by the hungover Fred.

But this is incorrect, which we can see as follows. Suppose now a shoe store representative, Helen, comes to the factory just after Gretchen’s quality control. Helen decides to play a guessing game with her, as follows. She picks up each C or D shoe  and tries to guess in which bin Fred had put it. For a shoe that ended up C, she has slightly better luck guessing  that it came from Fred’s bin C, and similarly with D.Why is this? Simply because the result that Gretchen found was more likely to have come from a state favoring that outcome (a state created by Fred’s sloppy measurement) than from a state inhibiting that outcome. We don’t in fact need Merlin the Magician to explain any of this. The situation is no different conceptually from being able to predict that a person coming to the U.S. from Poland is more likely to be of Polish ancestry than, say, Japanese ancestry. The fact that we now see that the person came from Poland does not retroactively cause the person to have been born of Polish parents!

So the next time you see claims such as  “future measurements affect past measurement results,” be wary. None of the quantum shoes sorted by Fred were subject to a Merlin-like retrocausal influence from Gretchen. Fred simply tilted the shoes to  states more likely to end up with one property, upon measurement, than the other. And this is all that is demonstrated by these kinds of experiments: standard quantum mechanics.