## TL;DR

Quantum mechanics (Planck 1900, Bohr, Heisenberg, Schrödinger, 1920s) describes physical phenomena at atomic and subatomic scales. Fundamental principles: wave-particle duality, quantization (energy in discrete units), uncertainty principle (cannot simultaneously know position and momentum precisely), superposition, entanglement.

## Core Explanation

Double-slit experiment: single particles create interference patterns — wave-particle duality demonstrated. Schrödinger equation: iℏ ∂ψ/∂t = Hψ (predicts wavefunction evolution). Copenhagen interpretation: measurement collapses wavefunction. Entanglement (Einstein's 'spooky action at a distance'): particles correlated regardless of distance. Applications: transistors, lasers, MRI, quantum computing.

## Further Reading

- [Principles of Quantum Mechanics (Shankar)](https://link.springer.com/book/9780306447907)