Physics and Philosophy (1958) by Werner Heisenberg

Physics and Philosophy (1958) by Werner Heisenberg

In another life, I would’ve liked to be a theoretical physicist. I’m endlessly fascinated by how the universe works on a fundamental level. But not only am I too dumb to be a scientist, I’m also too frustrated by ambiguity to handle the implications of quantum theory.

Heisenberg himself is one of the fathers of quantum mechanics, with his role developing both the “Copenhagen interpretation” of the theory and his own namesake, the “uncertainty principle”. This book is his account of quantum theory’s development, and how philosophical views on physics have evolved since the earliest great minds like Aristotle first attempted to grasp the world in its most elementary form.

The satisfying objectivity of classical Newtonian physics may still hold true at our average, everyday scale, but quantum theory takes hold when we shrink our scope to the subatomic level - where the act of measurement itself affects the results of observation. Here, all measurements become, at best, statistical probabilities rather than hard data. For example, in trying to identify the position of an electron, the light emitted from the subatomic microscope is enough to displace it. Not only that - but Heisenberg’s own ‘uncertainty principle’ proves that we can’t know two interconnected aspects of the same particle (like position and velocity) at the same time. And what’s worse is that those electrons can’t even be universally understood as ‘particles’ in the first place, because some of their properties can only be measured by treating them as waves. A counter-proposal I quite like regarding quantum theory suggests a ‘hidden variable’ that, if known, would presumably reconcile all the ambiguity inherent to the system. Unfortunately, this proposition was disproven almost as soon as it was introduced...

The biggest gut-punch of quantum theory, though, is that it’s incompatible with certain aspects of Einstein’s relativity, which reframed physics with an entirely novel view of space and time - where “the present” is actually a finite interval defined by the speed of light between event and observer - meaning events happening simultaneously for one observer are not technically occurring simultaneously for another observer who is in motion relative to the same events.

The underlying struggle seems to be the whole idea of the observer becoming an active part of measurement. This is where a lot of the philosophy comes in. We only know the world as we perceive it, but that doesn’t imply that our perception is accurate in a completely objective sense. This hearkens all the way back to Descartes’ “Cartesian Partition”, which identifies the relationship between knowledge of self, of God, and of the world. Quantum physics works within a similar “practical realism”, relying heavily on conditionally verified statements as we ourselves affect the world we observe (as opposed to the “dogmatic realism” at the foundation of classical physics, which recognizes only purely objective statements apart from ourselves).

The furthest stretch of this perception-dilemma takes form in “metaphysical realism”, which questions the very existence of anything, considering we can only judge reality by our perception of it. Even on a less far-reaching level, mechanical physics has its limits within traditional sciences like biology and psychology, where the intricacies of the mind and the question of what makes something “alive” can’t be explained by mere physicochemical functions.

Heisenberg doesn’t disparage the separation of scientific branches, though. He even draws a fascinating parallel to different forms of art. Art and science are both attempts to idealize and describe our experience in the world through a formalized ‘language’. And in essence, neither is more arbitrary an expression than the other.

A lot of early philosophizing about our world dealt with its fundamental substance - the same thing physics has mainly been working to discover since its inception. And here, quantum theory actually gives us solid footing, not only in upholding the laws of conservation of energy, but in clarifying that energy itself is, in fact, the fundamental substance of the universe. It seems like a strange concept when we’re so inclined to peg a particle, or matter, as the base unit of creation - but considering matter and energy are transmutable, this holds up perfectly (consider how atoms become energy in a nuclear explosion, and how particles can appear from pure kinetic energy at high-enough accelerations). In ancient Greece, Heraclitus was shockingly close to this conclusion with his idea of ‘force’ as the building block of nature. And others had equally interesting (and not entirely invalid) theories - like Anaximander’s proposition that an eternal, unknown element which, when unformed, is in perfect ‘Being’ - but is subject to material, earthly struggles in the process of ‘Becoming’, before ultimately reverting back to its shapeless, primary nature.

In spite of my own distaste for the ambiguity of quantum theory, Heisenberg points out that the goal of physics should be understanding the universe on an atomic level, not forcing atomic discoveries into a system by which we only wish they exist (however clean and convenient that may be). And I recognize that there’s a cheeky sort of beauty to the uncertainty of modern physics - even half a century after Heisenburg’s time, where there are still struggles to reconcile quantum mechanics with relativity, and we face new, baffling unknowns, like dark matter. It's as if God is willing to let us enjoy His cooking and even share most of His recipes with us, but still won’t let anyone in on the “secret sauce” at the heart of it all. And I guess I’m okay with that.