QBism

The Future of Quantum Physics

ISBN 9780674504646

Publication date: 10/03/2016

Measured by the accuracy of its predictions and the scope of its technological applications, quantum mechanics is one of the most successful theories in science—as well as one of the most misunderstood. The deeper meaning of quantum mechanics remains controversial almost a century after its invention. Providing a way past quantum theory’s paradoxes and puzzles, QBism offers a strikingly new interpretation that opens up for the nonspecialist reader the profound implications of quantum mechanics for how we understand and interact with the world.

Short for Quantum Bayesianism, QBism adapts many of the conventional features of quantum mechanics in light of a revised understanding of probability. Bayesian probability, unlike the standard “frequentist probability,” is defined as a numerical measure of the degree of an observer’s belief that a future event will occur or that a particular proposition is true. Bayesianism’s advantages over frequentist probability are that it is applicable to singular events, its probability estimates can be updated based on acquisition of new information, and it can effortlessly include frequentist results. But perhaps most important, much of the weirdness associated with quantum theory—the idea that an atom can be in two places at once, or that signals can travel faster than the speed of light, or that Schrödinger’s cat can be simultaneously dead and alive—dissolves under the lens of QBism.

Using straightforward language without equations, Hans Christian von Baeyer clarifies the meaning of quantum mechanics in a commonsense way that suggests a new approach to physics in general.

Praise

Hans Christian von Baeyer has done a wonderful job with this book. I’ve been fortunate enough to learn QBism twice in my life. The first time, it was the hard way, as colleagues and I battled out every nuance of the forming theory, always testing and retesting, tearing down and reconstructing—we had to turn our world upside down to get there. But the second time was pure pleasure as I learned the subject afresh from Professor von Baeyer’s masterful articulation of it. So many of his turns of phrase are insightful gems I never could have formulated myself. Now for the first time I believe I know how to teach the subject, and there is no better understanding one can have than that!

—Christopher A. Fuchs, Professor of Physics, University of Massachusetts Boston, and key architect of QBism
Physicists all agree on how to do calculations using quantum mechanics and disagree markedly on what those calculations really mean. With his customary humor and elegance, Professor von Baeyer walks us through one of the more recent attempts to understand the mysterious world inside the atom.

—James Trefil, Professor of Physics, George Mason University, and the author of Science in World History
QBism remains controversial, but scientifically inclined readers will share von Baeyer’s enthusiasm and come away with a feeling, if not a deep understanding, of quantum phenomena that doesn’t require suspension of disbelief.

—Kirkus Reviews
Von Baeyer offers a sensible approach to this seemingly esoteric world…He has an enthusiastic presentation and style that sweeps the reader along into the world of quantum physics and makes sense of it.

—Ralph Peterson, Manhattan Book Review
QBism should be applauded as a breeding ground of ideas for multiple disciplines including physics, philosophy, and mathematics, and von Baeyer’s book offers an account accessible to all…[It] provide[s] an outstanding introduction to two of the key components of QBism (quantum theory and subjective Bayesianism), and places the reader into the mind of the QBist in a way that will aid the ongoing debate over its merit. It is a worthwhile read.

—Kelvin J. McQueen, Quantum Times