Mind, Matter, and Quantum Mechanics
La proposta di Henry Stapp è in linea con l'interpretazione ontologica della meccanica quantistica, che è poi quella di Heisemberg. Questa alternativa considera che se la transizione del possibile al realizzato, ovvero il collasso della funzione
La proposta di Henry Stapp è in linea con l'interpretazione ontologica della meccanica quantistica, che è poi quella di Heisemberg. Questa alternativa considera che se la transizione del possibile al realizzato, ovvero il collasso della funzione d'onda, è causata dall'interazione che ha luogo tra il dispositivo che misura e la particola, allora il mondo che risulta dalla nostra osservazione sarà ontologicamente reale.
The transition from the “possible” to the “actual” takes place as soon as the interaction between the [atomic] object and the measuring device and thereby with the rest of the world...The mathematical probability function of quantum theory represents “our knowledge”.... What is the nature of that world? What sort of world do we live in? The world represented by an ontogically interpreted quantum theory, with the quantum jumps representing transitions from “possible” to “actual”...The actual events in quantum theory are likewise idealike: each such happening is a choice that selects as the “actual”, in a way not controlled by any known or purported mechanical law, one of the potentialities generated by the quantum-mechanical law of evolution. In view of these uniformly idealike characteristics of the quantum-physical world, the proper answer to our question “What sort of world do we live in?” would seem to be this: “We live in an idealike world, not a matterlike world.” The material aspects are exhausted in certain mathematical properties, and these mathematical features can be understood just as well (and in fact better) as characteristics of an evolving idealike structure. There is, in fact, in the quantum universe no natural place for matter. This conclusion, curiously, is the exact reverse of the circumstance that in the classical physical universe there was no natural place for mind...One possibility immediately opened up by this change is the possibility of integrating human consciousness into the physical sciences. This possibility was effectively blocked off when physical science meant, in the final analysis, classical physics. For there is an enormous conceptual gulf between the classical physicist’s conceptualization of the physical world and the psychologist’s conceptualization of the mental world. The essence of the classical physicist’s conception of matter is its local-reductionistic nature: the idea the physical world can be decomposed into elementary local quantities that interact only with immediately adjacent neighbors. (ppgg. 194-195)
Questa linea interpretativa, in cui secondo Heisemberg l'universo quantistico è un "qualcosa simile ad una idea", si oppone al fenomenalismo della scuola di Copenhagen, e apre la possibilità di integrare la coscienza umana nella fisica.
La soluzione del problema mente-materia è possibile se le due vengono considerate come le parti naturali di un tutto, in cui realtà fisica e realtà mentale interagiscono. Secondo questa ottica, la mente allora appartiene sì ad uno stato macroscopico, però al tempo stesso à anche molto sensibile a qualsiasi pur piccola variazione al livello sinaptico. Per cui bisogna aspettarci che essa si sviluppi in una condizione che rappresenta una superposition of macroscopically different alternative possibilities for the brain. (pag. 126)
Quando si parla di natura quantistica della mente vediamo che per ogni determinato evento non esiste una conoscenza aprioristica del risultato del comportamento dei processi neurali che determinano l'apprensione di tale istante; tale evento consolida una delle tante realtà alternative quante sono le variazioni sinaptiche possibili che agiscono in quel determinato momento. Per natura quantistica della mente si intende che ogni pensiero cosciente è un'unità; questa visione della realtà fisica inerente alla coscienza è comune sia ad Werner Heisemberg che a William James. According to William James our conscious thoughts have an eventlike quality: they appear as “buds” of reality—either all or nothing at all. This holistic “all or nothing at all” property is precisely the characteristic feature of quantum phenomena that distinguishes them from classical phenomena. (pag. 152)
Gli eventi quantistici non necessariamente accadono al livello delle scariche sinattiche, essi possono accadere al livello del cervello intero in congiunzione con il presentarsi del pensiero conscio come evento.
Unificata a questo punto la mente con il cervello, possiamo considerare ogni aspetto sia strutturale che funzionale di ciascun pensiero conscio come raffigurato dentro della rappresentazione fisica del cervello. Tutto questo però non introduce assolutamente la questione della mediazione: che cosa causa il presentarsi della transizione quantistica? Le cose accadono in maniera aleatoria oppure sono controllate sebbene a livelli ancora nascosti della realtà? Mentre nella fisica classica il corso degli eventi è determinato localmente in forma meccanica, nella fisica quantistica invece il processo di base genera principalmente probabilità o tendenze. Certamente ciò è assurdo da credere, qualcosa infatti deve selezionare quale dei possibili eventi debba accadere. Ma questo qualcosa non può essere locale e meccanico, perchè allora saremo ritornati alla fisica classica: esso deve, almeno in certe circostanze, permettere che vicende in una regione siano influenzate da una scelta umana fatta contemporaneamente in una regione distante. Inoltre questo processo veicola unità intrinseche che sono simultaneamente pensiero e materia (il cervello). Questi due aspetti rendono il processo quantistico simile alla sincronicità junghiana: entrambi sono acasuali ed entrambi manifestano strutture olistiche in un regno che giace tra il fisico e il psichico.
La teoria quantistica è governata da leggi che non sono deterministiche e che non fissano ciò che accade attualmente, ma danno solo delle probabilità. In parole di Heisemberg:
The observation itself changes the probability function discontinuously; it selects of all possible events the actual one that has taken place ...the transition from the “possible” to the “actual” takes place during the act of observation. If we want to describe what happens in an atomic event, we have to realize that the word “happens” can apply only to the observation, not to the state of affairs between two observations. It applies to the physical, not the psychic act of observation, and we may say that the transition from the “possible” to the “actual” takes place as soon as the interaction of the object with the measuring device, and thereby with the rest of the world, has come into play, it is not connected in the mind of the observer. (W. Heisenberg, Physics and Philosophy, Harper and Row, New York, 1958, chap. III.) (pag. 164)
Per comprendere la rilevanza dell'ontologia della coscienza di Heisemberg, dobbiamo applicarla ai cervelli.
The characteristic ontological quality of the Heisenberg actual event is its “actualness”; its property of being a “coming into beingness”. This property is also the ontological quality of a conscious event. Thus the conscious event and the (specified features of the) brain event are structurally and ontologically indistinguishable: these two corresponding events are, within the mathematical theory itself, the same thing. Consciousness is not, therefore, in this quantum-mechanical description of nature, something that hovers outside of space and matter, observing the mathematically described world but not influencing it. Rather, it is representable as an integral natural part of the basic dynamical process that gives form to the universe, and its structure is completely represented within the physicist’s mathematical description of nature. Let me elaborate upon this essential point. In Heisenberg’s ontology the basic process in nature is a sequence of actual events. Each of these events selects and actualizes some large-scale pattern of activity in some large physical system. This actualization is represented by a “quantum jump” in the Heisenberg state of the universe: the old state jumps to a new state. This new state specifies the tendencies for the next actual event, and so on. It is this sequence of actual events that creates the evolving form of the universe. The mental life of each human being is representable as a sub-sequence of the full sequence of Heisenberg events. (pag. 175)
This brain event actualizes a single coherent pattern of neural activity from a collection of patterns that were possible prior to that event...The place of human consciousness in this quantum universe is entirely different from the place of human consciousness in the classical universe. No longer is man an isolated and impotent cog in a mindless machine. Rather he is, through his consciousness, an integral part of the global, mindful, integrating process that gives form to the universe. (pag. 176)
Henry Stapp mette ad un certo punto a confronto le principali interpretazioni della fisica negli ultimi quattro secoli:
Three huge turnabouts in science occurred during the past four centuries. The first of the three great shifts was the creation of what is called “classical physics”. This development was initiated during the seventeenth century by Galileo, Descartes, and Newton, and was completed early in the twentieth century by the inclusion of Einstein’s theories of special and general relativity. The second major shift was the creation of quantum theory. This revision began at the outset of the twentieth century with Max Planck’s discovery of the quantum of action, and was completed in the years 1925 to 1927, principally by Heisenberg, Bohr, Pauli, Dirac, Schrödinger, and Max Born. The third crucial shift was the integration of the mental and physical aspects of nature. It was begun in the early 1930s by John von Neumann and Eugene Wigner, and has developed rapidly during the past decade.
The main theme of classical physics is that we live in a clocklike universe, and that even our bodies and brains are mechanical systems. The theory asserts that nature has a “material” part that consists of tiny localized bits of matter, and that every motion of each of these minute material elements is completely determined by contact interactions between adjacent material elements. This material part of nature includes our bodies and our brains. Hence, according to classical physics, each of our bodily actions is completely fixed by mechanical processes occurring at atomic or subatomic levels. Classical physics accommodates the existence also of another part of nature, which consists of our human thoughts, ideas, feelings, and sensations. However, the existence of these experiential aspects of nature is not entailed by the principles that govern the behavior of material parts.
During the twentieth century this classical theory of nature was found to be incompatible with the emerging empirical data pertaining to the detailed properties matter. A new approach, called quantum theory, was devised. It explains both all the empirical facts that are explained by classical physics, plus all of the newer experimental data in which the classical predictions fail. The new theory differs profoundly from its predecessor. Classical physics was a deterministic theory about postulated localized bits of matter, whereas quantum theory is a probabilistic theory about nonlocalized bits of information. This essentially subjective approach to physical theory was devised and promulgated by Niels Bohr, and the physicists that he gathered about him in Copenhagen. Hence it is known as the “Copenhagen interpretation”. It works exceedingly well in actual practice. In spite of the unparalleled practical success of the restricted program, some scientists have been unwilling to abandon the ideal that science should strive to find a rationally coherent conception of the reality that lies behind the empirical facts. The only successful effort in this direction that I know of is the one initiated by John von Neumann and Eugene Wigner. It accepts as real the subjective elements of experience that are the basic elements of Copenhagen quantum theory, and relates them to an equally real, but nonmaterial, objective physical universe. Under the impetus of the rapidly growing scientific interest in the connection between the objective and subjective aspects of nature the von Neumann–Wigner approach has been developed over the past decade into a post-Copenhagen quantum theory that explains a great deal of the detailed structure of the emerging data in this field. This development allows quantum theory to be elevated froma set of practically successful—but mysterious—rules, to a rationally coherent conception of man and nature. The basic theme of both Copenhagen and post-Copenhagen quantum theory is that the physical world must be understood in terms of information: the “tiny bits of matter” that classical physics had assumed the world to be built out of are replaced by spread-out nonmaterial structures that combine to form a new kind of physical reality. It consists of an objective carrier of a growing collection of “nonlocalized bits of information” that are dynamically related to experiential-type realities. Each subjective experience injects one bit of information into this objective store of information, which then specifies, via known mathematical laws, the relative probabilities for various possible future subjective experiences to occur. The physical world thus becomes an evolving structure of information, and of propensities for experiences to occur, rather than a mechanically evolving mindless material structure. This new quantum structure entails the validity of all the scientifically validated empirical data, while at the same time explaining how our thoughts can influence our actway concordant with our normal experience of that connection.
Another pertinent property of the new theory concerns “locality”. Classical dynamics is “local” in the sense that all causation is via contact interaction between neighboring bits of matter. Von Neumann–Wigner quantum theory violates that condition in two different ways. The first pertains to the mechanism by which a person’s thoughts influence his actions. That process is not a local process in which tiny elements act upon their neighbors. It is a process involving bits of information that reside in space-time structures that can extend over large portions of the person’s brain or body, and that are associated with whole experiences.
There is also a second way in which the action of subjective experiences upon the physical world turns out to be “nonlocal”: what a person decides to do in one place can instantly influence what is true in distant places. That feature seems, on the face of it, to contradict the theory of relativity, which forbids sending signals faster than light. The picture of nature that emerges is one in which the global evolution of the universe is controlled in part by choices made by localized agents, such as human beings. The causal roots, or origins, of these choices are not specified by any laws that we yet know or understand. In that very specific sense these choices are “free”. However, they can affect the behavior of the agent himself, and necessarily have, moreover, effects on faraway physical events.
What are the moral, social, and philosophical implications of this profound revision of our scientific understanding of man and nature? There has been a long-standing conflict between classical physics and rational moral philosophy: according to the precepts of classical physics each man is a machine ruled by local material processes alone, whereas rational moral philosophy is based on the presumption that what a normal human being knows and understands can make a difference in how he behaves. Jurisprudence is, accordingly, based on the premise that insofar as a person was able to know the nature and quality of the act he was doing or to know he was doing what was wrong, then he is responsible for that act.
Quantum theory, unlike classical physics, allows a person’s mental process to make a difference in how his body behaves. on Neumann quantum theory injects human thoughts into the causal structure of nature in an irreducible way that allows a person’s mental effort to influence his bodily actions. Thus twenty-first-century science, unlike nineteenth-century science, does not reduce human beings to mechanical automata, deluded by the scientifically unsupportable belief that their thoughts can make a difference in how they behave. Rather it elevates human beings to agents whose “free choices” can, according to the known laws, actually influence their behavior. (Capitolo 12)
Many physicists of today claim to believe that it is perfectly possible, and also satisfactory, for there to be choices that simply come out of nowhere at all. (pag. 190)
Stapp è molto critico verso il modo di concepire la realtà da parte della fisica classica, perchè considera che non integra l'esperienza umana in una forma corretta e completa:
Classical physics is not the ultimate scientific theory. It fails at the level of atomic phenomena, and has been replaced by quantum theory. However, the quantum laws, unlike the classical laws, are indeterministic: they fix not what actually happens, but only the probabilities for the various things that might happen. That is, quantum theory, in its orthodox form, provides no answer to the further question: What fixes what actually does happen? (pag. 160)
Any physical theory must, in order to be complete, specify how the elements of the theory are connected to human experience. In classical physics this connection is part of a metaphysical superstructure: it is not part of the core dynamical description. But in quantum theory this connection of the mathematically described physical state to conscious experiences is part of the essential dynamical structure. And this connecting process is not passive: it does not represent a mere witnessing of a physical feature of nature by a passive mind. Rather, the process is active: it injects into the physical state of the system being acted upon properties that depend upon the intentional chosen action of the observing agent.
Quantum theory is built upon the practical concept of intentional actions by agents. Each such action is expected or intended to produce an experiential response or feedback...Quantum theory is thus an information-based theory built upon the ledge-acquiring actions of agents, and the knowledge that these agents thereby acquire. (pag. 213)
In classical physics the elemental ingredients are tiny invisible bits of matter that are idealized miniaturized versions of the planets that we see in the heavens, and that move in ways unaffected by our consciousness, whereas in quantum physics the elemental ingredients are intentional actions by agents, the feedbacks arising from these actions, and the effects of our actions on the physical systems that our actions act upon...quantum theory may be able to provide the foundation of a scientific theory of the human person that is better able than classical physics to integrate the physical and psychological aspects of his nature. For quantum theory describes the effects of a person’s intentional actions upon the physical world, whereas classical physics systematically leaves these effects out. An intentional action by a human agent is partly an intention, described in psychological terms, and partly a physical action, described in physical terms. The feedback also is partly psychological and partly physical. Each intentional action depends, of course, on the intention of the agent, nd upon the state of the system upon which this action acts. (pag. 214)
Per Stapp il ruolo dell'osservatore è molto rilevante, e in questo aspetto ripristina e attualizza le teorie del fisico Von Neumann:
The observer, in order to get information about what is going on about him into his stream of consciousness, must, according to orthodox quantum mechanics, initiate probing actions. According to the development of the theory of von Neumann, the brain does most of the work. It creates, in an essentially mechanical way based on trialand-error learning, and also upon the current quantum state of the brain, a query/question. Each possible query is associated with a psychological projection into the future that specifies the brain’s computed “expectation” about what the feedback from the query will be.
The physical manifestation of this query is called “Process I” by von Neumann. It is a key and necessary element of the quantum dynamics: it resolves ambiguities that are not resolved by the physical laws of quantum mechanics, and it ties the physical description expressed in terms of the quantum mathematics to our communicable descriptions of our perceptions...
...The point, here, is that quantum mechanics has a built-in connection between a conscious intent and its physical effects. This connection is tied to the "Process I" probing actions, whose dynamical effects are specified by the quantum dynamical rules. Therefore our conscious intentions do not stand outside the dynamics as helpless, impotent witnesses, as they do in classical physics, but have specified dynamical effects (ppgg. 266 -267)
In sintesi tutta l'argomentazione di Henry Stapp appunta al fatto che la meccanica quantistica è la unica che, dentro dell'ottica scientifica, permette il corretto collegamento tra il proposito della coscienza e le sue conseguenze fisiche.