The Transactional Interpretation of Quantum Mechanics: The Reality of Possibility
Chapter 7: The Metaphysics of Possibility in PTI (EXCERPTED MATERIAL)
All material copyright © Ruth E. Kastner 2011
7.4 The macrosopic world in PTI
In this section, I consider macroscopic objects and the everyday level of experience in the transactional picture.
7.4.1 Macroscopic objects are based on networks of transactions
I said in the previous section that there are no individual ‘particles,’ just field excitations-- Heisenbergian ‘potentia’-- that can lead to observable events via actualized transactions. Here I wish to address the question: what is it about transactions that make events ‘observable’?
First, recall that it is only through actualized transactions that conserved physical quantities (such as energy, momentum, and angular momentum) can be transferred. Such transfers occur between emitters and absorbers which are also field currents (recall Chapter 6). Thus the supporting entities and structures for actualized transactions are generally only potentia themselves. The realizing of phenomena is a kind of ‘bootstrapping’ process in which actualized events are rooted in unactualized possibilities.
For a specific illustration, consider a baseball, depicted in Figure 7.4 as we ‘zoom in’ to view it on smaller and smaller scales. The third square represents molecular constituents; the fourth square, a Feynman diagram, represents interactions among subatomic constituents both within molecules (intramolecular forces) and between molecules (intermolecular forces). Bound systems such as atoms are only offer waves, but they can (and do) continually emit and absorb photons and other subatomic quanta. Those emitted quanta are absorbed by, for example, our sense organs, setting up enormous numbers of transactions transferring energy between ourselves and the atomic constituents of the baseball. The energy transfers effect changes in our brain, providing for our perception of the baseball.
fig7.4: Zooming in on a baseball.
Thus, in the TI (and PTI) picture, a necessary feature and key component of any observation of a system is absorption of offer waves and corresponding generation of confirmation waves. We can go further and make a general interpretational identification of absorption with observation in a way not available to traditional interpretations of quantum theory: absorption is the way the universe “observes itself” and makes things happen. This identification is possible because under TI, absorption plays an equal role with emission in the dynamics of an event. In contrast, traditional interpretations take emission as the entire dynamical story and then cannot account for why observations seem to have such a special role in the theory. As Feynman tells us, we should sum the amplitudes over ‘unobserved’ intermediate stages of an event to get a total amplitude for a final ‘observed’ event, and then take the square of that. Why should we square that amplitude, and why should Nature care whether we ‘observe’ or not in this algorithm? The only way that Nature could know or care would be because something physical really happens in such ‘observations,’ and the only possible physical process accompanying an ‘observation’ is absorption. Under traditional interpretations which neglect absorption, the above apparently inexplicable procedure leads us into an impenetrable thicket of anthropomorphic considerations of the supposed affect of a mental substance -- “consciousness” --- on a physical substance, namely a quantum system. In Feynman’s words: “Do not keep saying to yourself, if you can possible avoid it, "But how can it be like that?" because you will get 'down the drain', into a blind alley from which nobody has escaped. Nobody knows how it can be like that.” I suggest that an escape route from the ‘blind alley’ is indeed available; the price (or dividend, depending on one’s point of view) is taking absorption into account as a real dynamical process and embracing the implications for our world view, which are explored in this and the next chapter.
7.4.2 Macrosopic observation as primarily intersubjective.
Next, let’s consider a prototypical observation: once again, the two-slit experiment. Let’s assume that the quanta under study are monochromatic (single frequency) photons originating from a laser. In setting up the laser and the two screens, we handle macroscopic materials such as photographic plates. All of these actions consist of molecular level transactions between enormous numbers of atoms and between some of the surface atoms and our hands. Energy is transferred via these transactions from those emitters to absorbers on our bodies; that energy serves as input for additional emissions between our sense organs and absorbers in our nerves, and so on, culminating in transfers of energy to our brains. Brain changes make possible our perception that ‘something happened’ (recall, from Chapter 2, Descartes’ argument that it is not possible to observe anything that does not produce a perceptible change). But exactly what happened can vary considerably, depending on the specific transactions being actualized. A transaction between the photographic plate and my retina will not be the same as the transaction between another part of the plate and someone else’s retina, but the laws of physics ensure that all those many transactions are coordinated such that a coherent set of phenomena are created.
The point is that a macrosopic ‘observed event’ is generally the product of an enormous number of transactions, even for only one observer. If one wishes to have one’s observation corroborated, more transactions are required as another set of eyes, hands, etc. are introduced. These comprise a different set of absorbers, and the emitters may well be different as well. The transactions occurring for the second observer are not the same as those occurring for the first observer. For there to be corroboration, the two observers have to agree on macroscopic facts such as “There is a dark spot at position x=50” which can be instantiated by a large number of different sets of microscopic transactions. The process of corroboration is thus one of comparing the transaction-based perceptions of two (or more) different observers and deciding whether they represent the same macroscopic event. But the event itself can be no more than the sets of transactions taken as constituting it. It is always definable only in terms of the subjective or intersubjective experiences of an observer or observers.
The above should not be taken as a reversion to mere subjectivism, since for any individual transaction between emitter and absorber, there is an objective matter of fact concerning which transaction was actualized. Furthermore, there are certainly experiments in which an individual actualized transaction can be amplified to the macroscopic level, as in detection by a photomultiplier. But even in the case of amplification of a single transaction to the observable level, the type of event observed depends on what absorbers are present for the emitted quantum. In general, ordinary events are collections of enormous numbers of transactions, with different sets of transactions for different observers.
7.4.3 Implications for the Realism/Antirealism debate
The PTI account of observation provides for a synthesis of the longstanding ‘realism/antirealism’ dichotomy in that both doctrines can be seen as conveying a partial truth. Let us first briefly review these doctrines.
The doctrine of realism spans many forms, from the ‘naive realism’ most of us grow up believing, to much more sophisticated forms, including ‘scientific realism,’ that have evolved in philosophical debate. For our purposes, we can make do with a definition from the Stanford Encyclopedia of Philosophy: “Metaphysically, [scientific] realism is committed to the mind-independent existence of the world investigated by the sciences.” The world and the entities in it are assumed by the scientific realist to exist independently of our minds, perceptions, and knowledge. The objects in our world are considered as possessing definite properties, which we can come to know without fundamentally disturbing or changing those basic properties.
Antirealism denies this view; it asserts that objects of knowledge are dependent on (or constituted by) some form of subjectivity or mental substance. For example, the philosopher and Irish Cleric George Berkeley famously asserted -- and ably defended -- the doctrine ‘esse est percipi’ (to be is to be perceived) , and concluded that all objects are ultimately ideas in the mind of God). The work of Immanuel Kant (discussed previously in Chapter 2) is relevant to the realism/antirealism dichotomy because Kant asserted that the only world we can ever come to know is that which depends on the concepts and functions of the human mind: the world of appearance, or what he termed the ‘phenomenal’ realm. Kant did assert that there was ‘something else out there’; in his terms, the ‘noumenal’ realm, but it was a basic principle of his philosophy that we can never come to know this elusive realm, that which he called the ‘thing-in-itself.’ Devitt (1991) refers to Kant as a ‘weak realist’ because Kant did hold that there was something that existed independently of our knowledge, even if we could (according to Kant) never obtain knowledge about it.
In the latter 20th century, Kant’s basic approach evolved into a version of antirealism generally known as ‘constructivism.’ In Devitt’s terms, constructivism asserts that ‘we make the known world” (Devitt 1991, 236). He correctly (in my view) points out that much of the constructivist argument rests on a conflation of epistemological (knowledge-based), semantic (meaning-based), and ontological (metaphysical) issues. But despite these weaknesses in the usual sorts of arguments for constructivism, it is in quantum theory where this form of antirealism begins to gain traction because of the notorious dependence of property detection on what we choose to measure (recall Section 1.1). In contrast, realism demands that the object of knowledge is not fundamentally changed by observation.
We can formulate this dispute in terms of the subject-object distinction presupposed by any discussion about knowledge on the part of an observer (subject) and the aspect of the world he wishes to know about (object). In these terms, the realist believes that knowledge is object-driven, while the antirealist believes that knowledge is subject-driven. We can now make contact with PTI by identifying the ‘object’ with the offer wave and the ‘subject’ with the set of confirmations taking place upon absorption of the offer wave components. The latter can be thought of in terms of a particular experimental setup or just in terms of the sense organs of an observer.
With the above identification, PTI can resolve the realism/antirealism conflict by declaring a measured form of ‘victory’ for both sides. Realism correctly asserts that there truly is “something out there” that is independent of observation. In PTI terms, this is the object represented by a quantum state or offer wave . But Antirealism correctly asserts that the form that the ‘something’ takes is at least partly dependent on how it is observed (in physical terms, detected in an actualized transaction), which takes into account the types of confirmations generated by absorbers. Recall from Chapter 4 the man observing the table, reproduced here as Figure 7.5. It’s not the ‘categories’ or ‘concepts’ in his mind that do the primary work here, but simply the absorbers in his sense organs. Thus, the ‘subject-object’ dichotomy becomes the ‘confirmation-offer’ complementary relationship in PTI.
fig7.5 . Subject and object.
The foregoing “defangs” anti-realism in the following sense: it need not be anthropocentric, since in PTI, one can have an actual phenomenon/event in the absence of a ‘conscious observer.’ All one needs is emitters and absorbers, which are physical (if pre-spacetime) entities.
This formulation also provides a solution to a long-standing puzzle faced by Kant scholars. The problem is this: Kant insisted that knowledge of the phenomenal world was obtained by way of an interaction of human perceptual activity and concepts with the noumenal world. But the nature of this interaction was deeply obscure. If the noumenal object or ‘thing-in-itself’ was truly ‘unknowable,’ what sort of causal power could it have to produce knowledge, even if through human-centered concepts and perceptions? PTI provides at least a partial answer: the noumenal realm is the realm of offer waves; the phenomenal realm begins with their absorptions, which generate confirmations and ultimately specific actualized events. The nature of the interaction between the noumenal realm and the phenomenal realm is just the transactional process.
Thus, in Kantian terms, one can say that the knowable phenomenon is rooted in the unknowable noumenon (quantum entity or offer wave) which is answered by confirmations from absorbers in the sensory organs. Actualized transactions result in transfers of energy, which are processed by the senses and their attendant cognitive structures. There are two components to the latter process: (1) physical/ontological (the quantum transaction arising from absorption by the sense organs) and (2) epistemic (the subjective/theoretical concepts used to identify and understand the phenomenon arising from the transaction). The current work deals only with aspect (1) because that is all that is necessary to account for the basic phenomena (the ‘raw sense data’ as described in a Russellian or foundationalist account). As has been noted by other researchers (e.g., Kent 2010), having to bring in philosophies of mind or explicit psycho-physical dualism weakens the scientific account because there is no account of ‘mental substance’ in the exact science of physics. Traditional ‘collapse’ approaches inevitably must engage in forays into psychologism of this kind because there is no consistent way to break the linearity of the theory and thereby provide for a determinate result on the physical level without taking absorption into account.
Thus, the transactional model denies the strongest form of realism, namely the view that objects in their independent entirety are ‘directly given’ to the senses; but it provides support for what is termed ‘representational realism’. The latter assumes that what is directly present to the knower is not the object itself, but ‘sense data’ that make contact with the objectively existing external object and therefore provide authentic knowledge about it. In PTI, sense data are the product of the object, as a source of offer waves -- and the subject, as a set of absorbers. Together, the subject and object produce transactions that provide information about the object conditioned on the manner and circumstances under which it is perceived. The latter sentence is important: such knowledge is always only partial, since transactions vary depending on what types of absorbers are available to the offer waves comprising the object.
7.5 An example: phenomenon vs. noumenon.
This section makes contact with Shakespeare’s famous verse that opened this chapter. Let us consider an example of the way in which a phenomenal world of appearance, thought of as occurring in ‘spacetime,’ arises from a transcendent noumenal level in terms of an aspect of popular culture: internet-based ‘massive multiplayer online role playing games’ or MMORPGs, such as “World of Warcraft” or “Second Life”.
In the game Second Life, a player can access an online game environment by loading a software package on his local computer. The player uses the software to create for himself a character, or "avatar", which represents him in the online game environment. Let's call the human player ‘Jonathan’ and his game avatar ‘Jon.’ Once Jon is established in a game environment, he carries with him a point of view (POV) through which Jonathan can perceive what Jon perceives as the latter pursues his in-game career. Now, suppose Jonathan decides to have Jon create something—a table, for example. Jonathan can input certain commands through Jon into the game environment, and a ‘table’ will appear at the desired ‘location’ in Jon’s vicinity.
Now, consider another human player, Maria, whose game avatar is ‘Mia.’ Maria might be sitting at her computer in Sydney, Australia while Jonathan is in Montreal, Canada. Nevertheless, their avatars may be in the same game environment ‘room’, say the ‘Philosophy Library,’ where Jonathan/Jon has just created his ‘table’. Now, suppose Jon and Mia don’t know that they are only avatars, but assume themselves to be autonomous beings. We might imagine Jon and Mia discussing the table in front of them along the same lines as the discussion in Bertrand Russell’s The Problems of Philosophy, Chapter 1. For readers unfamiliar with this material, Russell’s discussion involves noting that the appearance of the table depends, to a great extent, on the different conditions under which it is viewed (or, more generally, perceived). These appearance may be mutually contradictory: for example, the table may appear smooth and shiny to the eye, but rough and textured under a microscope. Following this line of argument, Russell famously concludes that the only knowledge we can have of the table is of various aspects of its appearance, which must always be contingent on the conditions under which it is perceived; and that the ‘real’ table underneath the appearances -- whatever that might be -- is a deeply mysterious object. In his words: “Thus it becomes evident that the real table, if there is one, is not the same as what we immediately experience by sight 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. Hence, two very difficult questions at once arise; namely, (1) Is there a real table at all? (2) If so, what sort of object can it be?” (Russell 1959 , 11). Russell’s presentation is an account of the deep divide between, in Kant’s terms, the world of appearance (phenomenon) and the thing-in-itself (noumenon). (Notice how he repeats the phrase ‘if there is one,” to emphasize how little we really know about it.)
If Jon and Mia pursue this analysis, they, too, find that the only knowledge they have of the table is based on its appearance (which their human players can monitor on their computer screens showing their avatars’ POVs). Suppose the side of the table first facing Jon is black and other side, facing Mia, is white. Jon and Mia can talk to each other and discuss what they see, and they can agree to compare their perceptions by, say, changing places. Then Mia can confirm that the other side of the table is black, and vice versa. By performing this sorts of comparative observations, Mia and Jon can convince themselves that there ‘really is’ a table there because they can corroborate their different perceptions in a consistent way: their intersubjective observations form a coherent set. This suggests to them that there is ‘something out there’ that is the direct cause of their perceptions. In common-sense realist fashion, they might conclude that there is a ‘real’ table behind or underneath the appearances –a ‘table-in-itself’ -- that ‘causes and resembles’ their perceptions of it.
But what about Jonathan and Maria? They both know that, while the ‘table-in-itself’ could be said to be the cause of Jon and Mia’s perceptions of the game table, the ‘table-in-itself’ does not ‘resemble’ the game table at all. What is the ‘table-in-itself’? It is nothing more than information in the form of binary data, manipulated by the people who created the game and by the human users (Jonathan and Maria). Compared to the game table perceived by Jon and Mia, it is insubstantial, abstract. And yet clearly, it is the direct cause of the avatars’ perceptions of an ordinary table (the ‘table-of-appearance’) which, to them, is not just an ‘illusion’: the avatars cannot ignore it (for example, they will bump into it and may even incur physical damage if they try to run through it as if it isn’t really there). If a human user were to somehow speak to an avatar like Mia and tell her that the objects in her world are nothing but information, she would scoff at the suggestion, and might ask why she suffers damage if she falls off a cliff in her ‘only information’ world. To the avatars, their world is perfectly concrete and consequential.
What does this little parable tell us about our world of ‘ordinary’ objects-of-appearance; that is, our empirical world? It tells us that it is conceivable and even quite possible that the ‘table-in-itself’ of our world is a very different entity from what the table-of-appearance might suggest. Because we, and the objects around us, are governed by the laws of physics (the ‘rules of the game,’ if you will), we interact with them and are affected by them, and in that sense they are certainly real, just as the game-environment objects are real for Jon and Mia. But the ‘object-in-itself’ is precisely that aspect of the real object which is not perceived. If such an aspect exists at all, we can reasonably expect it to be on an entirely different level from our perceived world of experience. Indeed, in terms of PTI, the ‘object-in-itself’ can be considered to be the offer wave(s) giving rise to possible transactions establishing the appearances of the object. Just as the ‘table-in-itself’ behind the avatars’ table does not really live in their game world and is a kind of abstract information, so the offer waves giving rise to our real empirical objects do not live in spacetime and can be considered a kind of abstract but physically potent information – i.e., the physical possibilities first introduced in Chapter 4.
Now, recall from Chapter 2 that Kant asserted that the ‘thing-in-itself’ is unknowable. I wish to contest this, based on two main (disparate) points: (1) the fact that Kant has already been shown to have been mistaken in assuming that Euclidean (flat) space is one of the ‘categories of experience,’; and (2) the fact that perceiving (i.e., sensory perception) is not equivalent to knowing, since knowledge can also be obtained by intellectual (rational) means. Concerning (2), recall the arguments in Chapter 2 that an empirically successful principle-type theory can be taken as providing new theoretical referents to previously unknown structural properties of the world. Such an approach to new knowledge is an intellectual or rational one rather than an empirical one, the latter being dependent on observation through sensory perception (including the use of sense-enhancing technologies such as microscopes or telescopes), and therefore being subject to the limitations of appearance. In contrast, unexpected but fruitful theoretical development can be considered as pointing to an abstract (non-observable) level of reality inaccessible to observation, as in the postulation of atoms. The latter was an intellectual step forward in knowledge, not an empirical one.
Recall also that Bohr asserted that the quantum object is something “transcending the frame of space and time” – suggesting (albeit despite himself) an altogether metaphysically new type of entity. The Hilbert Space structure of quantum theory greatly exceeds the structure of the empirical world in that it precludes our ability to attribute always-determinate classical properties to objects (recall Chapter 1). Therefore, it’s natural to suppose that the structure of the theory describes something “transcending the frame of space and time” but which is nevertheless real because objects described by those Hilbert Space states can be created and manipulated in the laboratory.
Let us review the argument so far: players in an online game such as Second Life (SL) can intersubjectively confirm the existence of an object in the SL environment, just as people in our world can intersubjectively confirm the existence of a table. But the object-in- itself remains elusive, in that each observer who perceives the object perceives a different version of it. That’s because the object-in-itself exists in domain II (recall Figure 7.2) ; it is not observable because it is not actualized and therefore does not exist in the world of appearance (i.e, ‘spacetime’). At the game level, the object’s observation by a particular avatar Mia is contingent on a transaction between the avatar and an aspect of the object, that aspect being determined by the manner and circumstances under which the object-in-itself (OW) is received—i.e., the confirmation wave (CW) generated by the avatar. The CW consists in the user Maria turning on her computer, loading the game, accessing a particular location in the game world, and orienting her avatar Mia’s POV in the appropriate direction (all these being dictated by the information of domain II which is the data manipulated by the human players Jonathan and Maria). The ‘actualized transaction’ consists in Mia’s POV registering the appearance of the table by specifying which pixels on the screen should be colored red, green, etc. This is only possible because of two things: (1) Jon/Jonathan created the table ‘offer wave’ with specific properties and (2) Mia/Maria accessed the appropriate properties in order to receive the ‘offer wave’ and actualize its appearance in her POV.
We can use this model to immediately gain insight into the phenomenon of ‘nonlocality.’ While the avatars and their objects have a maximum speed c, Jonathan and Maria transcend the game environment and can freely communicate instantaneously (with respect to the game environment), so that information can be transmitted from one region in the game environment to any other at infinite speed. This is precisely because that information is not actually contained in the game environment. So, for example, Mia might shoot an arrow at game-speed c in Jon’s direction while Maria tells Jonathan (over the phone) that she is doing so. Instantly, Jon can step aside and miss the arrow, even though he should not be able to do so according to the rules of the game environment (which would preclude Jon from seeing the arrow coming at him). ‘Faster-than-light’ or ‘nonlocal’ influences are evidence of physically efficacious information existing on a level other than that of the usual local processes (i.e., the game environment or ‘spacetime’).
 Baseball image: Nutdanai Apikhomboonwaroot / FreeDigitalPhotos.net
The Messenger Lectures, 1964, MIT
 This description is not meant to be physiologically rigorous; it is merely an indication of how energy transfers via transactions ultimately result in brain changes.
 E.g., conservation of physical quantities corresponding to the symmetries of the system and compliance with such laws as the principle of least action.
 Subjectivism is the view that knowledge can only be about experiences of a perceiving subject and not about any genuine object external to the subject.
 From Chakravartty, Anjan, "Scientific Realism", The Stanford Encyclopedia of Philosophy (Summer 2011 Edition), Edward N. Zalta (ed.), URL = . I consider only the physical world, not social or political ‘worlds’ for the purposes of this work.
 This antirealist doctrine was primarily explicated in Berkeley’s Treatise Concerning the Principles of Human Knowledge (1710).
 The Bohmian theory provides a way to retain realism about quantum objects because it asserts that there really are quantum particles with definite positions, independently of our knowledge or concepts. (Bohmians acknowledge that we disturb those positions in an uncontrollable way when we measure certain contrasting (noncommuting) properties, but that if we choose to measure position, what we find is a particle position that existed independent of our observation. However, I do not favor the Bohmian theory because the ‘guided particle’ ontology is incompatible with the relativistic domain (e.g., recall that the classical electromagnetic field must be described by an indefinite number of quanta), there is no account of how guiding waves living in 3N-dimensional configuration space ‘guide’ particles in 3-space, and its account of the Born Rule can be only statistical in nature.
 In this regard, I do not deal in this work with the deep and subtle questions concerning the relationship of subjective perception to sense data, although I do assert that perception properly needs an object, even if not ‘physical’ in the usual sense: perception is transitive and presupposes the fundamental subject-object distinction. (In contrast, one might refer to a perception-free account of experience as awareness, which is the ability to perceive.) I assume that whatever it is that is subjectively perceived can be attributed to physical transfers of energy via actualized transactions. In cases of non-veridical or hallucinatory perception, an account may be possible in terms of atypical biological processes in the hallucinating subject which ultimately can be traced to transactions among the microscopic constituents of biological components (e.g., neurons).
 The naive realist notion that independently existing objects outside the mind are the causes of ideas (perceptions) that resemble them is extensively critiqued in Descartes’ Meditations.
 This could be considered the ‘Kant’s credibility is already suspect’ argument.
 This this is the case is demonstrated by the great empirical success of physical theories arrived at through rational analysis and mathematical invention. In Einstein’s words: “How can it be that mathematics, being after all a product of human thought independent of experience, is so admirably adapted to the objects of reality?” Einstein, A. (2010). Nature seems to be inherently mathematical and logical; were that not the case, theoretical science could not provide any useful knowledge.
 Here I endorse Hacking’s dictum that “if you can spray them then they are real” (Hacking 1983, p.23), referring to an experimentalist’s comment that he could ‘spray’ a piece of equipment with positrons.
 At a higher meta-level are the game designers who decide what types of OW can be created and how—the Gods of the Game, if you will.