Philosophy of Physics, or How to Invent New Science
For several decades, many physicists have complained that their science is in a crisis (cf. e.g. L. Smolin, The trouble with physics, 2006; Smolin has made outstanding contributions to present-day physics). The theory seems stuck in an impasse, and breakthrough ideas that could solve the big questions, such as the unification of gravity and quantum mechanics, seem far away. On top of that, it was recently discovered that as much as 96% of the energy-matter content of the universe is ‘dark’, meaning that it totally escapes theoretical understanding. How and why did such a crisis arise? This is one of the questions that will be addressed in this course.
In fact, Albert Einstein once suggested an answer. He warned that a science that forgets its historical lineage and is unclear about its philosophical assumptions is in danger. This is one of the theses that we will explore, namely that at the fundamental level physics and philosophy are solidly intertwined, and that conceptual (philosophical) thinking better be clear before jumping into mathematics. Einstein made his prophetic statement in relation to quantum mechanics, the theory of atoms and sub-atomic particles. He was always convinced that quantum mechanics was only an approximation and not a mature theory, citing how it was a probabilistic and not a deterministic science. But the question of determinism is typically a philosophical question, and has been investigated by almost all famous philosophers. How can philosophy inform the physical debate, as Einstein and many others requested?
More generally, we will investigate the philosophical assumptions at the basis of several great theories: Newton’s classical mechanics, Einstein’s theory of gravity (relativity theory), and the quantum mechanics of Planck, de Broglie, Bohr, Schroedinger, Heisenberg, etc. Our aim is to convey the idea that to invent new theories, it is essential to delve into philosophical questions; and conversely, that philosophy gains from its interaction with physics. Prerequisites for this course are a general and introductory high-school knowledge of physics and philosophy; and as much curiosity as possible.