Quantum Mechanics and the Crisis of Scientific Realism

Quantum mechanics is often celebrated as one of the greatest triumphs of modern science, but its deepest significance may lie in something far more unsettling. When physicists in the early twentieth century began probing the behavior of subatomic particles, they didn't just discover strange new phenomena. They arrived at what appeared to be a devastating challenge to the entire scientific enterprise. For the first time in the history of modern science, the critique of whether science can accurately describe reality wasn't coming from philosophers or skeptics on the outside. It was coming from within science itself, from the very experiments physicists were conducting in their own laboratories.

David Albert, professor of philosophy at Columbia University, tells that remarkable story from the ground up. He begins with a series of deceptively simple experiments involving electrons and their measurable properties, experiments that have actually been performed and whose results are beyond dispute. Through careful, step-by-step reasoning, you'll see how these experiments led brilliant thinkers like Niels Bohr to declare that the age-old aspiration of science to provide a complete, realistic picture of the physical world was naïve and impossible. You'll come to understand why smart, reflective people concluded that any attempt to describe what particles are doing behind the scenes would collapse into paradox or contradiction.

From there, Albert traces the efforts of figures like von Neumann, Schrödinger, and Wigner to push back against this radical conclusion and to try, despite Bohr's warnings, to tell a coherent story about what's actually happening in the subatomic world. These attempts introduce strange new ideas, like the notion that a particle can exist in a "superposition" where asking about its location is as meaningless as asking about the marital status of the number five. But they also run headlong into a formidable obstacle known as the measurement problem: the apparent need for two incompatible laws of nature, one for when particles are being observed and another for when they aren't.

Albert then turns to one of the most profound discoveries in the history of physics, John Bell's theorem and the fate of locality, our ancient conviction that distant events can only influence each other through a chain of local causes, like a row of falling dominoes. You'll learn why any realistic account of quantum mechanics must violate this deeply held intuition in shocking ways, and what that means for our understanding of the natural world.

Finally, Albert surveys the three most serious modern attempts to resolve the measurement problem: the GRW theory of Ghirardi, Rimini, and Weber, which adds a small stochastic modification to the Schrödinger equation; Hugh Everett's many-worlds interpretation, which keeps the equation untouched and lets every outcome occur in a branching universe; and David Bohm's pilot-wave theory, which restores particles to definite positions at all times, guided by a wave function. Throughout, Albert's emphasis is on making these ideas genuinely accessible, logically rigorous but free of unnecessary technical machinery, so that anyone can appreciate one of the most astonishing episodes in the history of human inquiry.

You can watch the lectures below, browse the chapter index, or watch on YouTube.