Notes on David Peat, Einstein's Moon: Bell's Theorem and the Curious Quest for Quantum Reality

Outline: "Bohm, Bell - and Boom! The End of Modern Dualism"

The End of Cartesian Dualism: Physics (re)discovers Philosophy: over against Cartesian and especially 19th ct. positivist dualisms which separate physics and philosophy - the emergence of quantum mechanics forces physicists to be become philosophers again. Indeed, the logic of complementarity which q.m. requires ripples into a larger (re)turn to complementary relationships between physics, philosophy, and religion.
(In other terms: Cartesian dualism defines both 19th ct. positivism and fundamentalism as "mirror images" of one another: each agree that only one mode of knowing can be true - and the alternative mode(s) must be false:

The end of Cartesian dualism thus undermines the dualistic epistemologies of both positivism and fundamentalism.)

First details: the indivisible wholeness of observer/observed, and particles as "standing probability waves" (re)turning us to the idealist epistemologies of Kant and Plato.

"Does the Moon exist when we're not looking?": Physicists do Ontology (The Bohr vs. Einstein debate over nonlocal vs. local reality and the EPR paradox [Peat, ch. 4, "Bohr vs. Einstein"])

Bell's Theorem: described by some as "the most significant discovery in the history of science," Bell's theorem provides a way to empirically test two competing epistemological and ontological/metaphysical hypotheses - the more idealist/instrumentalist/nonlocal reality assumptions of quantum mechanics vs. the more empiricist/realist/local reality assumptions of Einstein and Newtonian physics.
Experimental ("empirical") evidence falls clearly on the side of the idealist/instrumental/nonlocal reality assumptions of quantum mechanics. (That is, empiricism has proven idealism!)

Implications: the empirical confirmation of q.m. (a) demonstrates that the "classical" mechanistic/atomistic/deterministic assumptions of modern Cartesian/Newtonian science are at best a "useful fiction" for the scale of reality human beings ordinarily experience - but are not an accurate account of the world at its most fundamental levels. Rather, (b) the holistic and probabilistic accounts of quantum mechanics - expressed ultimately as mathematical equations describing only probabilities and potentials - (re)turn us to more holistic models and accounts of reality, consistent with such accounts as developed both by philosophers such as Plato and in Western and Eastern religious traditions.

Project: proposed assignments for synthesizing our survey of the history and philosophy of Western philosophy/science, from Thales through Quantum Mechanics.

The End of Cartesian Dualism: Physics (re)discovers Philosophy

Peat makes clear that "The objections of physicists of the caliber of Einstein, Planck, and Schrödinger to the new ideas that were emerging from Copenhagen forced Bohr and his two colleagues to create what philosophers call an epistemology - a theory of knowledge. In this case, it was a theory of what can be known about the atomic world. This theory has become known as the Copenhagen interpretation of quantum theory." (58)

Point: the positivist turn of the 19th ct. would have scientists (and with them, all right thinking persons hip to modernity...) jettison all matters "merely speculative," - i.e., all philosophical and religious discussion involving non-material entities whose existence could not be demonstrated in empirical ways. Such discussion, first of all, would include precisely the questions of epistemology and metaphysics.

What is nifty and striking about quantum mechanics, then, is that it forces - from within the domain of physics itself - scientists to turn to the traditionally philosophical task of constructing an epistemology.

In short: while positivists sought to banish all things philosophical and religious in the 19th ct. - developments in 20th ct. physics force a resurrection of such classical philosophical topics as epistemology and metaphysics.

[Historical point: this restoration of the "classical" complementarity between science and philosophy in part reflects the philosophical training of the European physicists responsible for both relativity theory and the Copenhagen Interpretation.

In particular, Heisenberg has written on the relationship between Kant's philosophy and quantum mechanics ("The Development of Philosophical Ideas Since Descartes in Comparison with the New Situation in Quantum Theory," in Physics and Philosophy: The Revolution in Modern Science) - as well as recounting a conversation among Carl Friedrich von Weizsäcker, himself, and the Neokantian philosopher Grete Hermann in the early 1930's ("Quantum Mechanics and Kantian Philosophy," in Physics and Beyond: Encounters and Conversations.)

This European inclusion of philosophy - even in the education of scientists and engineers - survives even today. For better or worse, it contrasts with the American system which characteristically ignores philosophy, especially in the training and education of scientists and engineers.]

Larger point: moreover, the kind of epistemology and metaphysics developed in the Copenhagen school, while including the empiricist side of philosophy/science, also (re)turn us squarely towards the idealist side of philosophy/science - specifically, the (neo)Kantian view that stresses that the knowing subject is inextricably bound up with the construction of what is known/experienced.

Another point: The complementarity at work in Quantum Mechanics - e.g., in the Heisenberg Uncertainty Principle (the more one knows about location, the less one knows about velocity and vice-versa) and the wave/particle duality of subatomic entities - thus not only represents a fundamental rejection of the Cartesian dualism that dominated modern science;

this complementarity further resonates with the complementarity apparent in the need for physicists - at least of the caliber of Bohr, Heisenberg, and Schrödinger - to also be philosophers (specifically, epistemologists and metaphysicians).

Indeed: as the connections between the world as understood at the quantum level and the essentially religious experiences of the world as an undivided wholeness suggest - this complementarity of ways of knowing can extend to religious experience as well.

(In this connection, the brief profile of George F. R. Ellis (Scientific American, October, 1995, 50-55), provides a concrete example of a more than competent cosmologist - one schooled under Fred Hoyle alongside Stephen Hawking - who is also a practicing religious person. Indeed, Ellis sees [and lives accordingly] a scientific case to be made for a natural moral law consistent with a principle of selflessness found in every world religion. Again, there is here a complementarity between religious and scientific modes of knowledge, over against the dualistic opposition between religion and science forced upon us by Descartes and articulated by the positivists.

Cf. as well the rôle of George La Mettre - a Catholic priest - in the development of the Big Bang theory, as nicely documented in the 2nd episode of Stephen Hawking's Universe.)

First details: the indivisible wholeness of observer/observed, and particles as "standing probability waves" (re)turning us to the idealist epistemologies of Kant and Plato

Given the basic principle of quantum theory - that the quantum (of energy) is indivisible -

• ...we can never know exactly where any quantum comes from - we can never divide it into contributions made by atom and by apparatus - which implies that the moment the detector and the atom interact, the whole situation becomes an unanalyzable whole. It is unanalyzable becuse it is no longer possible to partition the situation into apparatus + atom - the two are bound together by a single, indivisible quantum. In Bohr's words, there is "an indivisible wholeness," an unanalyzable wholeness. At the moment of observation, the observer and observed make a single, unified whole. (62)

This wholeness, moreover, means that it becomes problematic to speak of a particle as "having" properties (position, velocity) - because every measurement of these properties simultaneously means we interfere with the quantum objects we seek to know. Indeed,

Max Born's colleague Pascual Jordan declared that observations not only disturb what has to be measured, they produce it. In a measurement, "the electron is forced to a decision. We compel it to assume a definite position; previously it was, in general, neither here nor there, it had not yet made its decision for a definite position....We ourselves produce the results of the measurement." (quoted by Max Jammer, The Philosophy of Quantum Mechanics (New York: John Wiley, 1974)

On the other hand, when we are not observing an atom or electron, quantum theory dictates that we cannot even talk about its moving along a given path, or even of its being anywhere at all! According to Heisenberg, while measurements and laboratory observations are real, "the atoms or the elementary particles are not as real; they form a world of potentialities of possibilities, rather than one of things or facts." (Physics and Philosophy [New York: Harper Torchbooks, 1962]). (63: see also 64f.)

To make the point provocatively:

• quantum mechanics provides us with a mathematical account of the most fundamental levels of "reality" - one that is instrumentally useful insofar as it allows us to predict and control future events (just as the Ptolemaic [earth-centered] system worked to predict future celestial events)
  but at the same time, this most fundamental reality is both indeterministic (because the particle as a wave function is simply a description of the probabilities of its possible behaviors - no single possible behavior must occur) and, in a carefully understood sense, simply a matter of potential being (because the probabilities describe only what can happen under given circumstances - i.e., what is yet to be, not [precisely] what [currently] is).
  
  In historical terms - quantum mechanics returns us not only to the epistemology of the modern philosopher Kant -
  but also to the ontology or metaphysics of the ancient philosopher Aristotle, who sought to explain change in part as a process of potentialities (things which "exist" only as potentials, not as something actual) - becoming actualities.
  Likewise, quantum mechanics (re)turns us to Plato, who argued that the universal, unchanging, unitary mathematical and ideal "forms "of the particular, diverse and changing "things" given to us in sense experience are more "real" (ontology) and "true" (epistemology).

This means:

• those who reject the view of the world articulated by quantum mechanics because it apparently violates the "common sense" view of the world as defined by Newtonian physics (i.e., of a mechanical universe consisting of discrete pieces ["local" realities, as we will call them] whose interaction is fully determined by mechanical push-pull actions and forces);
  especially if this rejection turns on
  • a) a refusal to (re)turn from the atomism of modern science to
    the wholism of quantum mechanics (and subsequent theory, such as David Bohm's theory of quantum potential and implicate order), and
    b) a refusal to (re)turn from the dualism of modern science (which forces the either/or choice between science and philosophy and religion, as expressed in 19th ct. positivism and fundamentalism) to
• the complementarity of quantum mechanics (and thereby the complementarity between science/philosophy/religion a complementarity characteristic of philosophy/science through most of its history);
  - such a rejection seems strongly analogous to the initial rejections of "new" theories in earlier history, as these apparently overturn previously accepted views.

In sum: those who stubbornly hold to an atomistic, dualistic view of the world, as ostensibly "scientific," despite the developments of relativity and quantum mechanics, are the "flat-earthers" of our day.

In our day, the obstacle to changes in scientific views is not so much a monolithic religious orthodoxy - but a secular dogmatism that believes its views to be "scientific," despite what science now says.

Physicists do Ontology: "Does the Moon exist when we're not looking?" (The Bohr vs. Einstein debate over nonlocal vs. local reality and the EPR paradox [Peat, ch. 4, "Bohr vs. Einstein"])

Einstein resists q.m. because of its probabilistic character ("God does not play dice," to quote the famous phrase), and because both the epistemology and ontology of the Copenhagen Interpretation clashed with his classical (Newtonian) belief regarding the essential separateness of subject and object - and the belief that an external reality does exist, independent of the subject/observer:

• This reality of Einstein's is known as a "local" reality. Each system or object can be defined and understood in its own particular region of space. Objects have their own independent existence, and if they change, then it must be as the result of interactions or forces acting from outside. These forces can also be defined in an objective way through the laws of nature. There are no mysterious "actions at a distance," no mystical influences. Objects possess properties, Einstein said. They move along paths; their fates are determined.
  But then Bohr and Heisenberg came along with complementarity and the uncertainty principle. They denied that the electron has a path, or even that it possesses any intrinsic properties like position and velocity. In fact, they seemed to be saying that the only reality one can talk about lies in the mathematical equations, and that there is no point in trying to construct mental models of the quantum world. To Einstein this was a "tranquilizing philosophy" (as he put it in a letter to Schrödinger), a metaphysical approach to the world that induced a sleep of the mind by smothering questions about the ultimate nature of the quantum world. The Copenhagen interpretation was nothing more than "a soft pillow on which to lay one's head"; it was not a true theory of nature or an attempt to engage reality face to face, but an encouragement to daydream. (69)

Out of this resistance comes Einstein's effort to refute q.m. - most powerfully, in the Einstein-Podalsky-Rosen paradox.

The EPR paradox argues that we can get around the indeterminacy principle by taking the measurement of a particle's velocity or position as a way of "knowing" about its twin's velocity or position - apparently in contradiction to the Copenhagen Interpretation which says the velocity or position cannot be known until it is measured.

Bohr's refutation of this is to point out that the paradox assumes what q.m. and the Copenhagen Interpretation deny - and what is at stake in the debate between Einstein and Bohr - namely, that the twin particle "has" any such property as velocity or location apart from measurement of the property. (See Peat, 79-81)

In logical terms, the EPR paradox begs the question.

In still other terms, Einstein's insistence on an independent reality with properties that exist apart from and prior to our knowing these in a measurement is a violation of strict empiricism - which demands that terms have no meaning unless those terms can be anchored in an empirical/sense experience.

Interestingly, Pauli sees Einstein's insistence on the independent existence of particles and their properties as parallel to a notorious example of merely speculative metaphysics - i.e., the [alleged] discussion as to how many angels can sit on the point of a needle. (The Bohr-Einstein Letters [New York: Walker, 1971], quoted in Peat, 83.)

This "metaphysical" (my term) insistence on an independent, external reality, note, contrasts with the account of the world provided by q.m.:

• Bohr had said, "There is no quantum world. There is only an abstract quantum mechanical description." Heisenberg had echoed, "The atoms or the elementary particles are not real; they form a world of potentialities and possibilities rather than one of things or facts." (Peat, 85)
  Cf.: "...the wave function [of the primordial source of the universe] is not real; it is simply a device used in the mathematics of quantum theory. Indeed, it is a wave of probability rather than an oscillation of matter. What the wave function describes is the probability that a particle will be discovered in a particular region of space should a measurment be carried out. This same wave function is also the mathematical tool used to predict the outcome of other experimental measurements. So what sense does it make to talk about the reality of wave functions and quantum states when no laboratory apparatus is around - indeed, when no large-scale world yet exists?" (86)

This abstract, unreal world of potentialities and possibilities, however, resembles Plato and Aristotle's "metaphysical" accounts much more than Einstein's apparently "common sense" (pre-Kantian?) insistence on an independent, external reality!

[Historical note: there is apparently no record of any medieval discussion of how many angels could sit/dance on the head of a pin/needle. This is apparently modernist propoganda intended to denigrate the ways of knowing of an earlier time in the effort to demonstrate the superiority of "modern" ways of knowing, i.e., natural science.]

Bell's Theorem

The point here is that the debate between Einstein and Bohr over reality - i.e., whether indeed an independent, external reality exists apart from the observer ("Is the moon there when you're not looking?") - moved from a philosophical debate to a scientific one: with Bell's theorem, it became possible to test the two metaphysical assumptions, i.e., the Einsteinian assumption of a local reality (independent of the observer, etc.) vs. the Copenhagen Interpretation of q.m. (see p. 94)

In particular, Bell's theorem demonstrates a contrast between the correlation to be found between measurements on twin particles:

• if local reality is correct, the correlation will lie between -2 and 2;
  if q.m. is correct, the correlation (e.g., for detectors at 45 degrees) = 2.83

These numbers mean, notice:

• ...the quantum world is more highly correlated than any world that depends on a local reality or locally operating hidden variables. (112)

The Experiments:

Briefly, the experimental work confirms the q.m. prediction, not the correlation predicted for local reality.

Implications:

While contemporary physicists/scientists may wish to ignore the "metaphysical" questions and implications surrounding "nonlocality" as now demonstrated via Bell's theorem and the Aspect experiments - Peat suggests that this effort at ignorance is parallel to an earlier reponse, namely, the response to Newton's conception of gravity as "action at a distance." (126)

Indeed, the demonstration of nonlocality is a fundamental paradigm shift out of Newtonian mechanics:

• ...physics had been wedded to locality, to systems that were well defined within their own particular regions of space and time, and to interactions that involved the transmissions of physical energy across space. The idea of nonlocality appears to deny this most basic fact of everyday experience, for it suggests that distant systems can be connected in a totally new way - a way in which distance no longer seems to matter. (127)

Among the many implications which Peat discusses, let me stress those under the heading "A Connected Universe" (156ff.)

Most generally, quantum mechanics appears to force us to recognize the limits of the "classical" Cartesian/Newtonian atomism and mechanistic picture of the world. While this picture works at a certain scale of reality ("between" the subatomic and the relativistic) - it is not an accurate account of all of reality, nor of "reality" at its most fundamental level.

Rather - if q.m. is correct, "reality" is unitary and connected in ways that correlate nicely with, for example, the direct experiences of connectedness reported in all religious traditions (cf. Peat, 158f.)

This wholeness and connectedness as a starting point (cf. Peat, 160) - over against the modern presumption of atomism and difference - further correlate with Platonic and Pauline conceptions of wholeness/health (i.e., of the body and psyche whose health consists in the harmonic working together of all the parts, as each part does its proper function in the right proportion to the other parts - a notion which also defines justice for Plato in the Republic, as it defines the harmony of the "body of Christ" for Paul [I Corinthians 11]).

Finally, the implication Peat draws from David Bohm's notions of quantum potential and the implicate order - i.e., of "gentle action" at the "edges" of a system, in order to effect significant and dramatic changes at the "center" (cf. Peat, 160-164) - correlate nicely with

• a) especially Hindu, Buddhist, and Taoist ideas of "actionless action"
  (non-attachment to the +/- consequences of our acts, undertaken for their own sake, not for the sake of self, in the Bhagavad-Gita;
  wu-wei in Taoism;
  non-interference in Buddhist traditions), and
  b) notions of "self-emptying" (kenosis ) in especially Greek-Christian traditions (so Ellis).

Project: we will use the week of Oct. 27-31 to "catch our breath" a bit - i.e., to review and synthesize, so as to construct a large picture of the history and philosophy of science we have examined so far.

Possibilities:

a) review class notes and web materials to focus on the role of mathematics in the history of philosophy/science, beginning with Thales and the PreSocratics, and focusing especially on the role of mathematics in Plato's theory of knowledge and metaphysics - a role that suggests the greater importance and reality of mathematics over our more direct experience of the "sensible" world.

In particular, how does

Plato's account of physics as, at best, "a likely story" (because its rootedness in the experience of shadows and the cave, as distinct from the truer and more real mathematical and ideal realities, prevents it from attaining the greater certainty and truth of mathematical and philosophical knowledge)

compare with

the projects of Copernicus and Kepler, whose religious (neopythagorean/neoplatonic) beliefs drove their development of new mathematical systems for "explaining" the universe?

In particular, how does

Plato's account of physics as, at best, "a likely story" (because its rootedness in the experience of shadows and the cave, as distinct from the truer and more real mathematical and ideal realities, prevents it from attaining the greater certainty and truth of mathematical and philosophical knowledge)

compare with

the Copenhagen Interpretation - in which the mathematical description of the photon, the electron, etc. as a "standing probability wave" is the final truth of things, and any description we may attempt to develop of quantum mechanical behavior using the terms and concepts developed in and appropriate to the macroatomic world of our experience (e.g., "wave," "particle," "spin," "velocity," "location," etc.) is only an approximation of such behaviors (indeed, approximations which are at best, incomplete and paradoxical as these macroatomic conceptions ultimately fail to accurately "picture" or capture the whole truth of quantum behaviors - a truth capturable only in the mathematics)?

b) review the first two episodes of Stephen Hawking's Universe, as possible resources for teaching history and philosophy of science.

i) How does the presentation of the "Galileo affair"in the video (episode one) compare with the account we have developed?

What do the differences between the video account and our account suggest about the larger, "popular" understanding of the relation between religion and science?

Given these differences, where might the "popular" understanding derive from? (That is, would the "popular" understanding, as stressing the conflict and opposition between religion and science, at least be consistent with (a) a Cartesian dualism in our epistemology - one that leads us to a forced choice between religion and science as modes of knowledge - a choice historically expressed in (b) the nineteenth century as positivism on the one hand and fundamentalism on the other hand? [Be sure to review the web documents on positivism and fundamentalism.])

ii) How does the presentation of the development of the Big Bang theory (episode two) suggest the complementary relationship between science and religion?

How is this complementary relationship consistent with the various complementarities we have seen in

(a) quantum mechanics,

(b) the larger complementarities opened up again by quantum mechanics between physics and philosophy (especially epistemology) and religion, and

(c) the complementarities between religion and philosophy/science we have seen in the history of philosophy/science?

c) Review the two articles byHeisenberg (noted above) on the relationship between Descartes, Kant, and quantum mechanics.

i) How does Heisenberg's view of especially the neokantian character of the Copenhagen Interpretation of quantum theory fit with the views we have seen expressed by Pine, Peat, and others?

ii) What does Heisenberg's view suggest regarding the relationship between physics and philosophy (i.e., oppositional or complementary)?

iii) How does the relationship between physics and philosophy suggested by Heisenberg compare with:

(a) the positivist and fundamentalist assumptions regarding the relationships between science and philosophy and religion - and, more broadly, the relationships between science and philosophy and religion possible under a Cartesian epistemology and metaphysics?

(b) the relationship between science, philosophy, and religion we have seen at work in the history of philosophy/science from Thales through Copernicus, Kepler, and Newton?