Fifteen Eighty Four

Quantum mechanics—one of the most puzzling and fascinating areas of modern science—has captivated both physicists and the public for over a century. From Einstein’s skepticism about its strange implications to the mysterious behavior of particles that seem to communicate instantaneously across vast distances, quantum theory constantly challenges our understanding of the universe.

In my new book, Contextual Reinterpretation of Quantum Nonlocality, I explore these enduring questions and offer a fresh perspective on quantum physics based on my experiences at the annual Växjö conference series in Sweden. Since 2000, the Växjö conference has become a key event for discussions on quantum foundations, information, and probability. It has brought together some of the brightest minds in the field, providing me with the unique opportunity to engage in discussions with world-renowned experts and explore some of the deepest questions in quantum theory. As the Silver Jubilee conference approaches in 2025, I’ve been reflecting on the incredible range of views and the diverse insights that have shaped my thinking on these topics.

One central idea that I critically explore in my book is quantum nonlocality—the notion that particles can influence one another instantaneously, even if they are light-years apart. This “spooky action at a distance,” as Einstein famously called it, has been a subject of intense debate ever since it was first suggested. But in my view, nonlocality isn’t the ultimate answer. Instead, contextuality—a concept that emphasizes how the results of quantum measurements depend on the experimental context (“Bohr’s contextuality”)—provides a more elegant and coherent solution to these mysteries. Bohr’s contextuality proposes that the properties of quantum systems aren’t simply intrinsic to the system itself, but are also shaped by the context in which they are measured. This idea is central to my book and offers a way to resolve some of the puzzles that quantum mechanics presents, such as the seemingly paradoxical nature of quantum entanglement and the violation of local realism. Here I follow Bohr whose complementarity principle has the contextual component. This component becomes evident through the disintegration of Bohr’s complementarity principle and its information interpretation. This principle, in turn, is based on the quantum postulate, the existence of the indivisible quantum of action, the Planck constant.  

One of the most famous thought experiments in quantum mechanics is the “EPR paradox”, proposed by Einstein, Podolsky, and Rosen in 1935. In fact, the EPR paradox challenged the Copenhagen interpretation. The role of the quantum state interpretation in the EPR argument is typically not highlighted and in contrast the role of nonlocality is emphasized. In my book, I argue that the ensemble interpretation—which was championed by Einstein and then widely advertised by Ballentine—offers a way to resolve the EPR paradox without resorting to nonlocality. This interpretation (that is due to Einstein) focuses on the statistical properties of quantum systems rather than treating individual quantum events as somehow “instantaneously connected.”

In addition to revisiting the EPR paradox, my book explores the deeper philosophical relationship between Bohr and Einstein, two of the central figures in the development of quantum mechanics. While their views often seemed at odds, I propose that contextuality offers a way to merge their perspectives, creating a more unified understanding of quantum theory.

The contextual interpretation of quantum state is closely coupled to the family of information interpretations which were presented at the Växjö conferences, of Brukner-Zeilinger, Cocke, D’Ariano, Fuchs (QBism), Khrennikov (Växjö interpretation), Plotnitsky (Reality without Realism). The contextual interpretation is coupled to contextual probability that can be treated as a form of generalized probability theory (operational measurement theory).  The book presents the corresponding calculus of  quantum instruments. 

Another fascinating area I discuss in the book is the classical-quantum interrelation—how classical and quantum theories are intertwined. One chapter is dedicated to the concept of classical Brownian entanglement, which connects classical statistical mechanics to quantum behavior. To understand this connection more deeply, I draw on the Bild concept, developed by Hertz and Boltzmann and later applied to quantum mechanics by Schrödinger. This concept helps bridge the gap between classical and quantum physics, offering insights that can lead to a more holistic understanding of the physical world.

The book also delves into Bell’s inequality, one of the most important tests in quantum physics. Bell’s inequality has been used to demonstrate the incompatibility of local realism and quantum mechanics, often cited as evidence of nonlocality. However, I argue that Bell’s inequality can be interpreted in a way that does not require nonlocality, but rather highlights the incompatibility of local observables of Alice and Bob.

Through all these discussions, my book also reflects on my personal experiences at the Växjö conferences, where I had the privilege of interacting with experts in quantum foundations and hearing a range of views on these complex issues. The preface includes my recollections of these conversations, offering a behind-the-scenes look at the intellectual exchanges that shaped my thinking.

Ultimately, Contextual Reinterpretation of Quantum Nonlocality invites readers to reconsider some of the foundational ideas of quantum theory. Whether you’re an expert in the field or someone with a keen interest in the fascinating world of quantum mechanics, this book offers a new perspective on how contextuality and complementarity can help resolve the mysteries of quantum physics. It’s a journey that not only tackles the technical aspects of the theory but also delves into the philosophical and conceptual issues that are essential for a deeper understanding of the quantum world. I hope this book will inspire further exploration of the ideas that continue to shape the future of quantum theory and technology, and I invite you to join me on this intellectual adventure.

Title: Contextual Reinterpretation of Quantum Nonlocality

ISBN: 9781009313476

Author: Andrei Khrennikov