The Feynman Lectures are one of the most popular lecture series in physics. They are great for science enthusiasts, students, teachers, and are just fantastic in general. Well, good news, Caltech and The Feynman Lectures website have collaborated to put these lectures online completely free of cost.

The lectures themselves were first presented at Caltech in the 1960s by the legendary physicist Richard Feynman. The lectures have combined and put into a 3 volume book. To date, about 1.5-million English copies have been sold (but, it’s free now, so that number will probably stagnate).

The online edition “has been designed for ease of reading on devices of any size or shape,” so mobile and tablet users are welcome. You can go to the main page for the lectures, or start with Volume 1, Volume 2, or Volume 3 if you like.

You can also watch the Feynman lectures below. They contain the same information as the books, so you can actually sit in Feynman’s class and listen to his lecture as he gave it 50 years ago.

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Lecture 1: The Law of Gravitation

Lecture 2: The Relation of Mathematics to Physics

Lecture 3: The Great Conservation Principles

Lecture 4: Symmetry in Physical Law

Lecture 5: The Distinction of Past and Future

Lecture 6: Probability and Uncertainty—The Quantum Mechanical View of Nature

Lecture 7: Seeking New Laws