Einstein, Bohr and the war over quantum theory.

In defence of Copenhagenism

The non-relativistic quantum theory has been interpreted causally by de Broglie, David Bohm, and others, where a quantum entity is viewed as a particle with a definite position and momentum. This interpretation contrasts with the Copenhagen orthodox interpretation, which conveys uncertainty through the commutator relationship between position and momentum operators. This is further exacerbated by the de Broglie-Bohm interpretation, which uses no operators corresponding to these observables. We reconcile these opposing viewpoints by introducing mathematical nonlinear transforms in Bohmian mechanics for the momentum observable. While these nonlinear operator-like transforms cannot be easily represented as matrices in the Hilbert space, we show that they can be utilized in the de Broglie-Bohm interpretations of quantum theory.

For the last decade I have been demonstrating that many of the so-called paradoxes generated by the Copenhagen interpretation of quantum mechanics have less puzzling analogs in nonlinear dynamics and chaos theory. This raises questions about the possibility of nonlinearities inherent in the foundations of quantum theory. Since most of us do not think intuitively with nonlinear logic, I take this opportunity to dwell on several peculiarities of nonlinear dynamics and chaos: nonlinear logic itself and the possible connection of infinite nonlinear regressions with free will. Superficially, nonlinear dynamics can be every bit as counterintuitive as quantum theory; yet, its apparent paradoxes are more amenable to logical analysis. As a result, using nonlinear dynamics to resolve quantum paradoxes winds up being more straightforward than many of the alternative interpretations currently being formulated to replace the orthodox interpretation. Chaos theory could be a candidate for bridging the gap between the determinism so dear to Einstein and the statistical interpretation of the Copenhagen School: For deterministic chaos is indeed deterministic; however, intrinsic limitations on precision in measuring initial conditions necessitate analyzing it statistically. Einstein and Bohr both could have been correct in their debates.

Quantum information technology mainly includes quantum communication, quantum radar, quantum computer these three aspects, in recent years, rapid development, many countries invested heavily in development. The awarding of the Nobel Prize in Physics in 2022 to three scientists for their work in quantum informatics has further stimulated people's interest in quantum theory, which has been studied and discussed. This paper not only reviews the historical situation, but also thinks and innovates in theory. The main contents of this paper are as follows: It is pointed out that there are fundamental contradictions between relativity and quantum mechanics; The wave function, quantum statistics and uncertainty principle are discussed in detail. The hidden variable theory is reviewed and the Bell inequality is discussed. The Aspect two-photon experiment was analyzed. The rationality of Bohm experiment scheme is discussed. The development of Bell type experiment is discussed. It is pointed out that the entangled state is not acting at a distance but propagating faster than the speed of light. Reviews the Copenhagen interpretation of quantum mechanics; Quantum communication and Wootters theorem are discussed. etc. This paper holds that quantum mechanics has been finalized from 1926 to 1928, and its basic content has not changed much. But for some of the accusations, it is necessary to answer them theoretically. For example, we believe that the Copenhagen interpretation fundamentally changes our understanding of nature and marks a profound revolution in physics. And no other theory has since emerged that has such a profound understanding and wide application of microscopic phenomena as this interpretation. Another example is Bohm's two-particle correlation spin scheme in quantum entanglement experiments, which has been proved to be effective in a series of experiments, which is an important contribution in Bohm's life. This paper holds that the so-called quantum field theory is a failure, and the original quantum mechanics should still be advocated today. Current theoretical research should pay great attention to quantum entangled states, because its nature is still unclear. Understanding this "first mystery of the physical world" not only has scientific significance, but also has great philosophical significance for understanding the universe.

Quantum indeterminism seems incompatible with Kant's defense of causality in his Second Analogy. The Copenhagen interpretation also takes quantum theory as evidence for anti-realism. This first article of a two-part series argues that the law of causality, as transcendental, applies only to the world as observable, not to hypothetical (unobservable) objects such as quarks, detectable only by high energy accelerators. Taking Planck's constant and the speed of light as the lower and upper bounds of observability provides a way of interpreting the observables of quantum mechanics as empirically real even though they are transcendentally (i.e., pre-observationally) ideal.

In his paper on the Cat’s uncertain situation between life and death, S. intended to criticize the Copenhagen interpretation of Quantum Mechanics and, conversely, to assert the consistency of his own wavelike view of the theory. His ideas contrasted with Heisenberg and Bohr’s positions, but also with Einstein’s attempt at a classically statistical interpretation of a quantum theory. His criticism therefore did not intend to discredit the whole Quantum Mechanics. In the fifties, he proposed a second quantization approach to a many particles state of the theory, which included his New Statistics. He asserted that the new approach modified some aspects of his famous 1926 equations. In my paper, I argue that S.’s new ideas in the fifties are related to his 1920 and 1926 contributions on rarified gas theory.

We consider a novel approach to address the black hole information paradox. The idea is based on adapting, to the situation at hand, the modified versions of quantum theory involving spontaneous stochastic dynamical collapse of quantum states, which have been considered in attempts to deal with shortcomings of the standard Copenhagen interpretation of quantum mechanics, in particular, the issue known as ``the measurement problem.'' The new basic hypothesis is that the modified quantum behavior is enhanced in the region of high curvature so that the information encoded in the initial quantum state of the matter fields is rapidly erased as the black hole singularity is approached. We show that in this manner the complete evaporation of the black hole via Hawking radiation can be understood as involving no paradox. Calculations are performed using a modified version of quantum theory known as ``continuous spontaneous localization'' (CSL), which was originally developed in the context of many-particle nonrelativistic quantum mechanics. We use a version of CSL tailored to quantum field theory and applied in the context of the two -dimensional Callan-Giddings-Harvey-Strominger model. Although the role of quantum gravity in this picture is restricted to the resolution of the singularity, related studies suggest that there might be further connections.

The realist’s criticisms of the Copenhagen Interpretation (CI) try to reestablish an ontological understanding of the wave particle dualism by classical spacetime notions. Investigating some of the original papers it can be shown that the founders of quantum theory were very careful with respect to that classical pictorial way of thinking. Especially the history of the debate on the foundation of QM make it clear that up to now there is no alternative to the CI.

The pragmatic interpretation of quantum theory is defined.This refinement of the orthodox Copenhagen interpretation covers both the relativiatic S-matrix form of quantum theory and also the ordinary nonrelativistic form.The connection of the pragmatic interpretation to the Copenhagen interpretation is described. Contrasts with several other interpretations are drawn.This report is part of a series of LBL reports with principal title "Foundations of S-matrix Theory".The earlier reports are LBL-759 Rev., LBL-956, and IBL-959.Other reports will follow.

The interpretative framework of quantum mechanics loosely subsumed under the name “Copenhagen interpretation” contains two central assumptions which seem incompatible with a quantum cosmology built on a covariant quantum theory of spacetime. The first is a distinguished class of classical systems. The second is a distinguished time variable and its associated notion of causality. The first assumption is incompatible with the uniform application of quantum mechanics to the universe as a whole. The second is incompatible with the general covariance of gravitational theory. This paper explores the possibility that both of these distinguished features of our world arise, not as special features of the formalism of quantum mechanics, but rather as consequences of specific initial conditions for cosmology.

A new situation is developing in the Bohr-Einstein discussion on the nature of the wave — particle dualism in individual microobjects, a controversy which has never stopped despite the majority position occupied by Bohr’s Copenhagen interpretation. This situation is not difficult to understand. Until a very recent period one could only observe statistical distributions of microscopic particles which all turned out to be correctly described by the mathematical formalism of quantum theory, so that one could not distinguish between the alternative possible conflicting interpretations such as the Heisenberg-Born-Pauli or de Broglie-Bohm points of view developed by their respective followers. This situation has recently changed for two main reasons: 1. The expansion of modern technology has now made possible individual observation/detection of individual particles associated with point-like exchange of quanta. One has thus recently observed the interference with themselves of individual neutrons, photons, and electrons in double slit experiments. All quantum experiments boil down to the analysis of individual localized particle impacts (quantum exchanges) whose statistical distribution always (up to now) confirms the validity of the quantum mechanical formalism. We live in a particle world. One only observes particles directly: the physical reality of all fields (such as gravitational, electromagnetic, and ψ fields) being indirectly inferred from their action on the observed sets of “particle” distributions.

Within the past decade there has grown an acute and highly articulate group of critics of the orthodox interpretation of quantum theory,—the so-called “Copenhagen Interpretation.” The writings of people like Bopp, Janossy, and particularly Bohm and Feyerabend, must be taken very seriously indeed. The future of some important discussions in the philosophy and the logic of science rests with these individuals. But they have, in their own writings, occasionally matched the inelegancies of Bohr and Heisenberg with as many inelegancies of their own. The present paper is meant to present a quintet of considerations which may possibly lead to a reassessment of the issues between Bohr, Heisenberg, and their critics, especially Bohm and Feyerabend.

Standard quantum theory is highly successful in all its applications, from photons and atoms, to semiconductors, superconductors, quarks, and so on. Yet the need to understand what the theory is really trying to tell us about the nature of the world beyond specific predictions forces us into the realm of philosophy, or, as some have dubbed it, quantum metaphysics: the study of the interpretation of quantum mechanics. There is a wide range of opinions regarding the philosophical foundations of quantum mechanics. This chapter focuses on two of the most prominent interpretations: the Copenhagen interpretation, and one alternative interpretation that has been gaining some support in recent years, the many-worlds interpretation (MWI), also known as the many universes interpretation. The central issues of contention are: firstly, that the measurement of some attribute of a quantum system generally involves the probabilistic collapse, or reduction, of the state vector where the probabilistic nature of the process is inherent—that is, not reducible to a more fundamental, deterministic explanation; and, secondly, the problem of bringing a measurement to a completion—a problem generally known as the measurement paradox.

For more than eighty years, quantum theory (QT) has dominated physical science. This domination remains unchallenged to this day. Some physicists celebrate this remarkable stability. Others lament this fact and argue that QT inhibits our understanding of physical reality. They feel that numerous problems that have accumulated in physical science require stepping beyond the horizon outlined by QT. The article offers a critical examination of the foundational assumptions of QT that shape its practice. It uses two interpretations of QT as case studies—Copenhagen interpretation and the theoretical perspective advanced by American physicist David Bohm—to explain one major problem that continues to plague our study of physics. The article sketches a path to a possible solution and outlines a new science practice that this solution will require.

One of the main challenges in theoretical physics over the last five decades has been to reconcile quantum mechanics with general relativity into a theory of quantum gravity. However, such a theory has been proved to be hard to attain due to i) conceptual difficulties present in both the component theories (General Relativity (GR) and Quantum Theory); ii) lack of experimental evidence, since the regimes at which quantum gravity is expected to be applicable are far beyond the range of conceivable experiments. Despite these difficulties, various approaches for a theory of Quantum Gravity have been developed. In this thesis we focus on two such approaches: Loop Quantum Gravity and the Topos theoretic approach. The choice fell on these approaches because, although they both reject the Copenhagen interpretation of quantum theory, their underpinning philosophical approach to formulating a quantum theory of gravity are radically different. In particular LQG is a rather conservative scheme, inheriting all the formalism of both GR and Quantum Theory, as it tries to bring to its logical extreme consequences the possibility of combining the two. On the other hand, the Topos approach involves the idea that a radical change of perspective is needed in order to solve the problem of quantum gravity, especially in regard to the fundamental concepts of `space' and `time'. Given the partial successes of both approaches, the hope is that it might be possible to find a common ground in which each approach can enrich the other.