Quantum Reality

Quantum Reality: Beyond the New Physics
Author	Nick Herbert
Cover artist	Mort Weiss, Tita Nasol
Subject	Quantum physics
Published	1985 (Anchor Books/Doubleday)
Pages	268
ISBN	978-0-385-18704-6
Dewey Decimal	530.1'2 82-46033
LC Class	QC174.12.H47 1985

Last updated May 02, 2024

Quantum Reality is a 1985 popular science book by physicist Nick Herbert, a member of the Fundamental Fysiks Group which was formed to explore the philosophical implications of quantum theory.^[1] The book attempts to address the ontology of quantum objects, their attributes, and their interactions, without reliance on advanced mathematical concepts. Herbert discusses the most common interpretations of quantum mechanics and their consequences in turn, highlighting the conceptual advantages and drawbacks of each.^[2]

Synopsis

Background

Following a brief summary of the experimental crises (such as the ultraviolet catastrophe) which motivated quantum theory, Herbert identifies four major formulations of quantum theory: Werner Heisenberg's matrix mechanics, Erwin Schrödinger's wave mechanics, Paul Dirac's transformation theory, and Richard Feynman's sum-over-histories formulation.^[2]^: 41–53

In introducing quantum objects (which he dubs "quons"), Herbert describes how quantum properties inhere in a wave function, which serves as a proxy for the measurement of these properties. He likens the quantum measurement process to mathematically treating the wave function as a summation of waveforms of a particular family, with various families corresponding to particular properties. The bandwidth of the spectrum of these waveforms represents the uncertainty in the quantum measurement. Herbert shows that for pairs of conjugate variables, such as position and momentum, these bandwidths are linked such that their product has a finite lower bound, thereby illustrating the basis of Heisenberg's uncertainty principle: any single property can be measured to arbitrary precision, but conjugate properties cannot simultaneously be known to arbitrary precision.^[2]^: 71–112

Herbert identifies two philosophical problems presented by quantum theory—the interpretation question, concerning the physical nature of the reality underlying observation; and the measurement problem , concerning the apparently special role of the measurement act in quantum theory, and various approaches to formally defining the measurement act.^[2]^{: 113–156}

Eight interpretations

Herbert identifies eight interpretations of quantum mechanics, all consistent with observation and with the aforementioned mathematical formalisms. He likens these different interpretations to the story of the blind men and an elephant—different approaches to the same underlying reality, which yield remarkably different (but often overlapping) pictures. The interpretations identified by Herbert are:

The Copenhagen interpretation, Part I ("There is no deep reality.") Most notably associated with Niels Bohr and Werner Heisenberg, Herbert identifies this as the most broadly accepted interpretation among physicists. In this interpretation, dynamic attributes do not describe the reality of quantum objects themselves, but inhere instead in the relationship between the observed object and the measurement device.^[2]^{: 158–164}
The Copenhagen interpretation, Part II ("Reality is created by observation.") In this variation of the Copenhagen interpretation, associated with John Archibald Wheeler, the reality of quantum attributes is created in the act of observation, as illustrated by the example of Wheeler's delayed choice experiment.^[2]^{: 164–168}
"Reality is an undivided wholeness." This interpretation, associated with David Bohm and Walter Heitler, suggests that the state of the entire universe may be implicated in any quantum measurement. Herbert highlights the apparent interaction of widely separated entangled particles, which may be represented by a single combined wave function, or "shared reality", in a high-dimensional configuration space.^[2]^{: 168–172}
The many-worlds interpretation . Devised by Hugh Everett, this interpretation does away with the conceptual problem of wave function collapse by supposing that all possible outcomes occur equally, in a constantly branching tree of parallel universes.^[2]^{: 172–175}
Quantum logic ("The world obeys a non-human kind of reasoning.") Associated with John von Neumann, Garrett Birkhoff, and David Finkelstein, this interpretation holds that quantum objects do possess innate attributes, but that the relationships between these attributes are governed by a non-distributive lattice, or "wave logic", unlike the Boolean lattice governing classical objects. In the example of the "three-polarizer paradox", two stacked, orthogonally-oriented polarizers will not allow any light to pass through (the meet of the sets of photons which will pass through each filter is null), yet the insertion of a diagonally-oriented polarizer between them allows some light to pass through the stack. The paradox can be understood by considering a polarized beam as a superposition, with diagonal components that interfere destructively.^[2]^{: 177–185}
Neorealism ("The world is made of ordinary objects.") Constructed by David Bohm and also associated with Louis de Broglie, this interpretation holds that quantum objects possess definite attributes, but that these attributes can change value instantly in response to events anywhere in the universe, with this information encoded in a physical pilot wave which must be able to travel faster than light. Other physicists attempted to construct object-based models which did away with this superluminal communication, but Bell's theorem later proved this to be impossible. For this reason, according to Herbert, neorealism is rejected by most of the physics establishment.^[2]^{: 185–189}
"Consciousness creates reality." First proposed by John von Neumann, this interpretation grants special status to conscious minds as the location of wave function collapse, in which the myriad possibilities of a quantum system are narrowed to one observed state. Unlike the Copenhagen interpretation, in which the observer selects which attribute will be seen to have a definite value but does not determine the value itself, von Neumann contended that the actual attribute value is determined in a collapse that occurs at the interface of the brain and the mind.^[2]^{: 189–193}
"The duplex world of Werner Heisenberg." Heisenberg recognized a division inherent in the Copenhagen interpretation, between the concrete actuality (phenomenon) of observations and the range of potentiality (noumenon) described by the wave function. In seeking to address the ontological nature of the unobserved world, he considered quantum theory to be not merely a successful mathematical analogy, but a literal description of the underlying reality. In Herbert's description of Heisenberg's view, the unobserved world is a world composed of possibility, qualitatively less real than the world of observed fact.^[2]^{: 193–195}

Bell's theorem and its implications

Adding a further wrinkle to the nature of quantum reality, Herbert presents the EPR paradox, and its resolution in the form of Bell's theorem. The EPR paradox, resting on the long-held assumption of locality, suggests the existence of "elements of reality"—unmeasured quantum attributes which are nonetheless real—which are not predicted by quantum theory. Bell's theorem resolves this paradox by proving that locality is ruled out by observation—that any model of reality consistent with observation must allow for non-local interaction. However, Herbert is careful to note, Bell's theorem does not entail any prediction of experimentally observable non-local phenomena, nor does it allow for superluminal communication.^[2]^{: 211–231}

Herbert then re-evaluates the aforementioned interpretations of quantum reality in light of Bell's theorem:

In the case of the Copenhagen interpretation, the "experimental arrangement" of observed entity and measurement device in which quantum attributes reside—considered by Bohr to be limited to the local interaction—must be expanded to include potentially distant objects with which these systems may be entangled.^[2]^{: 240–241}
According to Herbert, Bell's theorem supports the Bohmian notion of underlying reality as an undivided wholeness.^[2]^{: 241–242}
Although Herbert asserts that the many-worlds interpretation lacks the counterfactual definiteness required to prove Bell's theorem, he contends that the many-worlds view is inherently non-local, by any reasonable conception of locality.^[2]^: 242
In Herbert's view, Bell's result strikes a major blow to neorealist models, by showing that the ostensibly real pilot wave must violate Einstein's universal speed limit.^[2]^{: 243–244}

Herbert concludes that, although Bell's theorem does not preclude any of the aforementioned interpretations of quantum mechanics, it insists that any valid interpretation must allow for non-local interaction.^[2]^: 245

Reception

In its review of Quantum Reality, The New York Times praised Herbert's efforts at making the subject matter comprehensible to a lay audience.^[3] Physicist Heinz Pagels called Quantum Reality "a great place for the general reader to begin to learn about quantum physics".^[4] Kirkus Reviews , however, concluded that Quantum Reality, while engaging, may leave lay readers confused.^[5]

Post-anarchist writer Hakim Bey used Quantum Reality as the basis for an analysis of the field of quantum physics in terms of the social paradigms that it may influence, and from which it may draw its metaphors.^[6]

Physicist David Kaiser, who has written about the Fundamental Fysiks Group to which Herbert belonged, claims that the book is used in undergraduate physics courses.^[1]

Quantum Reality has been translated into German, Japanese, and Portuguese.^[7]

Related Research Articles

The Copenhagen interpretation is a collection of views about the meaning of quantum mechanics, stemming from the work of Niels Bohr, Werner Heisenberg, Max Born, and others. The term "Copenhagen interpretation" was apparently coined by Heisenberg during the 1950s to refer to ideas developed in the 1925–1927 period, glossing over his disagreements with Bohr. Consequently, there is no definitive historical statement of what the interpretation entails.

The many-worlds interpretation (MWI) is a philosophical position about how the mathematics used in quantum mechanics relates to physical reality. It asserts that the universal wavefunction is objectively real, and that there is no wave function collapse. This implies that all possible outcomes of quantum measurements are physically realized in some "world" or universe. In contrast to some other interpretations, the evolution of reality as a whole in MWI is rigidly deterministic and local. Many-worlds is also called the relative state formulation or the Everett interpretation, after physicist Hugh Everett, who first proposed it in 1957. Bryce DeWitt popularized the formulation and named it many-worlds in the 1970s.

In quantum mechanics, Schrödinger's cat is a thought experiment, sometimes described as a paradox, of quantum superposition. In the thought experiment, a hypothetical cat may be considered simultaneously both alive and dead, while it is unobserved in a closed box, as a result of its fate being linked to a random subatomic event that may or may not occur. This thought experiment was devised by physicist Erwin Schrödinger in 1935 in a discussion with Albert Einstein to illustrate what Schrödinger saw as the problems of the Copenhagen interpretation of quantum mechanics.

In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of measurements that have not been performed. The term "counterfactual definiteness" is used in discussions of physics calculations, especially those related to the phenomenon called quantum entanglement and those related to the Bell inequalities. In such discussions "meaningfully" means the ability to treat these unmeasured results on an equal footing with measured results in statistical calculations. It is this aspect of counterfactual definiteness that is of direct relevance to physics and mathematical models of physical systems and not philosophical concerns regarding the meaning of unmeasured results.

An interpretation of quantum mechanics is an attempt to explain how the mathematical theory of quantum mechanics might correspond to experienced reality. Although quantum mechanics has held up to rigorous and extremely precise tests in an extraordinarily broad range of experiments, there exist a number of contending schools of thought over their interpretation. These views on interpretation differ on such fundamental questions as whether quantum mechanics is deterministic or stochastic, local or non-local, which elements of quantum mechanics can be considered real, and what the nature of measurement is, among other matters.

<span class="mw-page-title-main">Wigner's friend</span> Thought experiment in theoretical quantum physics

Wigner's friend is a thought experiment in theoretical quantum physics, first published by the Hungarian-American physicist Eugene Wigner in 1961, and further developed by David Deutsch in 1985. The scenario involves an indirect observation of a quantum measurement: An observer $observes another observer who performs a quantum measurement on a physical system. The two observers then formulate a statement about the physical system's state after the measurement according to the laws of quantum theory. In the Copenhagen interpretation, the resulting statements of the two observers contradict each other. This reflects a seeming incompatibility of two laws in the Copenhagen interpretation: the deterministic and continuous time evolution of the state of a closed system and the nondeterministic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox.$

In quantum mechanics, wave function collapse, also called reduction of the state vector, occurs when a wave function—initially in a superposition of several eigenstates—reduces to a single eigenstate due to interaction with the external world. This interaction is called an observation, and is the essence of a measurement in quantum mechanics, which connects the wave function with classical observables such as position and momentum. Collapse is one of the two processes by which quantum systems evolve in time; the other is the continuous evolution governed by the Schrödinger equation.

In philosophy, the philosophy of physics deals with conceptual and interpretational issues in modern physics, many of which overlap with research done by certain kinds of theoretical physicists. Historically, philosophers of physics have engaged with questions such as the nature of space, time, matter and the laws that govern their interactions, as well as the epistemological and ontological basis of the theories used by practicing physicists. The discipline draws upon insights from various areas of philosophy, including metaphysics, epistemology, and philosophy of science, while also engaging with the latest developments in theoretical and experimental physics.

In physics, a hidden-variable theory is a deterministic physical model which seeks to explain the probabilistic nature of quantum mechanics by introducing additional variables.

The transactional interpretation of quantum mechanics (TIQM) takes the wave function of the standard quantum formalism, and its complex conjugate, to be retarded and advanced waves that form a quantum interaction as a Wheeler–Feynman handshake or transaction. It was first proposed in 1986 by John G. Cramer, who argues that it helps in developing intuition for quantum processes. He also suggests that it avoids the philosophical problems with the Copenhagen interpretation and the role of the observer, and also resolves various quantum paradoxes. TIQM formed a minor plot point in his science fiction novel Einstein's Bridge.

In quantum mechanics, the measurement problem is the problem of definite outcomes: quantum systems have superpositions but quantum measurements only give one definite result.

The Bohr–Einstein debates were a series of public disputes about quantum mechanics between Albert Einstein and Niels Bohr. Their debates are remembered because of their importance to the philosophy of science, insofar as the disagreements—and the outcome of Bohr's version of quantum mechanics becoming the prevalent view—form the root of the modern understanding of physics. Most of Bohr's version of the events held in the Solvay Conference in 1927 and other places was first written by Bohr decades later in an article titled, "Discussions with Einstein on Epistemological Problems in Atomic Physics". Based on the article, the philosophical issue of the debate was whether Bohr's Copenhagen interpretation of quantum mechanics, which centered on his belief of complementarity, was valid in explaining nature. Despite their differences of opinion and the succeeding discoveries that helped solidify quantum mechanics, Bohr and Einstein maintained a mutual admiration that was to last the rest of their lives.

In physics, complementarity is a conceptual aspect of quantum mechanics that Niels Bohr regarded as an essential feature of the theory. The complementarity principle holds that certain pairs of complementary properties cannot all be observed or measured simultaneously, for examples, position and momentum or wave and particle properties. In contemporary terms, complementarity encompasses both the uncertainty principle and wave-particle duality.

Classical Newtonian physics has, formally, been replaced by quantum mechanics on the small scale and relativity on the large scale. Because most humans continue to think in terms of the kind of events we perceive in the human scale of daily life, it became necessary to provide a new philosophical interpretation of classical physics. Classical mechanics worked extremely well within its domain of observation but made inaccurate predictions at very small scale – atomic scale systems – and when objects moved very fast or were very massive. Viewed through the lens of quantum mechanics or relativity, we can now see that classical physics, imported from the world of our everyday experience, includes notions for which there is no actual evidence. For example, one commonly held idea is that there exists one absolute time shared by all observers. Another is the idea that electrons are discrete entities like miniature planets that circle the nucleus in definite orbits^.

Quantum mechanics is the study of matter and its interactions with energy on the scale of atomic and subatomic particles. By contrast, classical physics explains matter and energy only on a scale familiar to human experience, including the behavior of astronomical bodies such as the moon. Classical physics is still used in much of modern science and technology. However, towards the end of the 19th century, scientists discovered phenomena in both the large (macro) and the small (micro) worlds that classical physics could not explain. The desire to resolve inconsistencies between observed phenomena and classical theory led to a revolution in physics, a shift in the original scientific paradigm: the development of quantum mechanics.

In physics, the observer effect is the disturbance of an observed system by the act of observation. This is often the result of utilizing instruments that, by necessity, alter the state of what they measure in some manner. A common example is checking the pressure in an automobile tire, which causes some of the air to escape, thereby changing the pressure to observe it. Similarly, seeing non-luminous objects requires light hitting the object to cause it to reflect that light. While the effects of observation are often negligible, the object still experiences a change. This effect can be found in many domains of physics, but can usually be reduced to insignificance by using different instruments or observation techniques.

Some interpretations of quantum mechanics posit a central role for an observer of a quantum phenomenon. The quantum mechanical observer is tied to the issue of observer effect, where a measurement necessarily requires interacting with the physical object being measured, affecting its properties through the interaction. The term "observable" has gained a technical meaning, denoting a Hermitian operator that represents a measurement.

The Fundamental Fysiks Group was founded in San Francisco in May 1975 by two physicists, Elizabeth Rauscher and George Weissmann, at the time both graduate students at the University of California, Berkeley. The group held informal discussions on Friday afternoons to explore the philosophical implications of quantum theory. Leading members included Fritjof Capra, John Clauser, Philippe Eberhard, Nick Herbert, Jack Sarfatti, Saul-Paul Sirag, Henry Stapp, and Fred Alan Wolf.

Epistemological Letters was a hand-typed, mimeographed "underground" newsletter about quantum physics that was distributed to a private mailing list, described by the physicist and Nobel laureate John Clauser as a "quantum subculture", between 1973 and 1984.

The von Neumann–Wigner interpretation, also described as "consciousness causes collapse", is an interpretation of quantum mechanics in which consciousness is postulated to be necessary for the completion of the process of quantum measurement.

References

1 2 Johnson, George (June 24, 1985). "What Physics Owes the Counterculture". The New York Times . Retrieved September 13, 2014.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Herbert, Nick (1985). Quantum Reality: Beyond the New Physics: An Excursion into Metaphysics and the Meaning of Reality . Anchor Books/Doubleday. ISBN 978-0-385-18704-6.
↑ Lehmann-Haupt, Christopher (June 24, 1985). "Quantum Reality". Books of the Times. The New York Times . Retrieved September 13, 2014.
↑ Nielsen, Tom. "References – Cosmos/Quantum". Enfolded.net. Archived from the original on June 22, 2015. Retrieved September 13, 2014.
↑ "Quantum Reality: Beyond the New Physics". Kirkus Reviews . Anchor/Doubleday. June 28, 1985. Retrieved September 13, 2014.
↑ Bey, Hakim. "Quantum Mechanics & Chaos Theory: Anarchist Meditations on N. Herbert's Quantum Reality: Beyond the New Physics". Hakim Bey and Ontological Anarchy. Retrieved December 5, 2022.
↑ Herbert, Nick (July 16, 2009). "A Book About Reality". Quantum Tantra. Retrieved September 13, 2014.

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[nyt2-1] 1 2 Johnson, George (June 24, 1985). "What Physics Owes the Counterculture". The New York Times . Retrieved September 13, 2014.

[qr-2] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Herbert, Nick (1985). Quantum Reality: Beyond the New Physics: An Excursion into Metaphysics and the Meaning of Reality . Anchor Books/Doubleday. ISBN 978-0-385-18704-6.

[nyt-3] Lehmann-Haupt, Christopher (June 24, 1985). "Quantum Reality". Books of the Times. The New York Times . Retrieved September 13, 2014.

[enfolded-4] Nielsen, Tom. "References – Cosmos/Quantum". Enfolded.net. Archived from the original on June 22, 2015. Retrieved September 13, 2014.

[kirkus-5] "Quantum Reality: Beyond the New Physics". Kirkus Reviews . Anchor/Doubleday. June 28, 1985. Retrieved September 13, 2014.

[bey-6] Bey, Hakim. "Quantum Mechanics & Chaos Theory: Anarchist Meditations on N. Herbert's Quantum Reality: Beyond the New Physics". Hakim Bey and Ontological Anarchy. Retrieved December 5, 2022.

[qt-7] Herbert, Nick (July 16, 2009). "A Book About Reality". Quantum Tantra. Retrieved September 13, 2014.

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