Quantum Foundations
open in notion ↗What quantum mechanics is actually saying about reality.
How quantum mechanics emerged 1900–1927 and the Bohr–Einstein fight that defined the field, from the 1927 Solvay Conference through EPR (1935) to Bell's theorem (1964). You cannot understand any modern debate without knowing this story.
The full interpretational landscape after Bell's theorem made quantum foundations a scientific problem: the major camps (Copenhagen, Many-Worlds, Bohmian, Objective Collapse, QBism, Relational) and the four key theorems — Bell, Kochen-Specker, PBR, and Frauchiger–Renner — each of which rules out a class of interpretations.
Where the field actually is right now (2025–2026): Wigner's-friend experiments, contextuality as a resource, reconstructions of QM from information-theoretic axioms, quantum reference frames, indefinite causal order, and GRW/spontaneous-collapse testing — the one part of foundations where empirical pressure is currently possible.
Optional side-quest on Jacob Barandes's "indivisible stochastic quantum mechanics" (2023–), a descendant of Nelson's stochastic mechanics, watched critically after Units 1–3 — seeing what Barandes addresses, what he sidesteps, and how his view fits in the landscape. Curt Jaimungal's seven-episode TOE series is the reason this curriculum was built.
Optional deepening on the cross-pollination of quantum foundations with quantum information — the most productive recent development in the field. This unit is also Unit 4 of the Information page and Unit 5 of the Math page: do it once, it counts three times.