“Chauncey Wright a nearly forgotten philosopher of real merit, taught me when young that I must not say necessary about the universe, that we don't know whether anything is necessary or not. So I describe myself as a bettabilitarian. I believe that we can bet on the behavior of the universe in its contact with us.” — Oliver Wendell Holmes, Jr.
Quantum theory is the great foundation for nearly all of modern physics. Since its discovery, it has never met a single experimental failure, and without it our technological society would not exist. Without quantum theory, there would be no transistors, no lasers, no smart phones—we might as well be living in 1907. But this foundation, as your previous lectures have surely emphasized, sits on shifty metaphysical sands. Some physicists look into quantum theory and see evidence that the universe is a vast web of superluminal connections; some look into it and see not one universe, but a continuum of parallel worlds. Still others—a tiny minority—look into quantum theory and see an overpowering message that its terms have not so much to do with nature itself, but with our place innature. This is the foundational stance of QBism. For QBism, the exclusive role of the quantum formalism is to make better decisions and better gambles as we confront nature. Metaphorically, the physicist is like a tiny euglena caught up in nature's stream, and quantum theory, like the euglena’s tail, is his best tool yet for navigating that course. But this is not to say that we might not learn about nature itself by studying the tool’s composition, form, and function. Not by accident, this takes us back to that year 1907, when William James—a friend of Holmes—first espoused the philosophy of “American pragmatism” at the Lowell Institute in Boston, Massachusetts, the speaker’s hometown. (Did you think I was going to say the studio of Pablo Picasso in 1907 as he painted Les Demoiselles d’Avignon?!) Crucial to pragmatism is the idea that our world is always on the make; the big bang is not just something remote and at the beginning of time, but intimate and all around us. With every quantum measurement we breathe a little more life into nature. As James put it during those Lowell Lectures, pragmatism gives a vision of the world where “new being comes in local spots and patches”. This in fact is the focal point of QBism's research program and the subject of this lecture 111 years later.
This talk is part of a Lecture series on foundations of physics: scientific realism (260020 VO, 2.5 ECTS, ufind.univie.ac.at/en/course.html) organised by the students of natural science of the University of Vienna (see naturwissenschaftscafe.wordpress.com)
