Lecture 3 | Modern Physics: Quantum Mechanics (Stanford)

The video runs approximately 1 hour and 40 minutes. It is the third lecture in Stanford University Professor Leonard Susskind's "Modern Physics" series, focusing on the fundamental framework of quantum mechanics. The course was recorded in early 2008 as part of Stanford's open courseware for the public, designed to help non-physics students develop an intuitive understanding of the quantum world. This lecture's highlights include Susskind's clear blackboard derivations and conversational explanations, which progressively build core concepts such as quantum states, observables, and the measurement postulate—while emphasizing their conflict with classical intuition, particularly regarding superposition and the role of probability amplitudes. He excels at using simple examples to raise profound questions, making abstract mathematics feel tangible. The lecture is well suited for beginners curious about quantum mechanics but lacking systematic training, STEM students looking to refresh foundational physics, and enthusiasts interested in approaching the subject from the perspective of the history of physics ideas. Viewing tips: No need to watch it all at once—pause to reflect on key derivations. If you find it challenging, familiarizing yourself with vectors and inner products from linear algebra beforehand will make the material much smoother. It is also recommended to watch the surrounding lectures in the series to build a coherent knowledge framework.