Dear Reader,

There are several reasons you might be seeing this page. In order to read the online edition of The Feynman Lectures on Physics, javascript must be supported by your browser and enabled. If you have have visited this website previously it's possible you may have a mixture of incompatible files (.js, .css, and .html) in your browser cache. If you use an ad blocker it may be preventing our pages from downloading necessary resources. So, please try the following: make sure javascript is enabled, clear your browser cache (at least of files from feynmanlectures.caltech.edu), turn off your browser extensions, and open this page:


If it does not open, or only shows you this message again, then please let us know:

This type of problem is rare, and there's a good chance it can be fixed if we have some clues about the cause. So, if you can, after enabling javascript, clearing the cache and disabling extensions, please open your browser's javascript console, load the page above, and if this generates any messages (particularly errors or warnings) on the console, then please make a copy (text or screenshot) of those messages and send them with the above-listed information to the email address given below.

By sending us information you will be helping not only yourself, but others who may be having similar problems accessing the online edition of The Feynman Lectures on Physics. Your time and consideration are greatly appreciated.

Best regards,
Mike Gottlieb
Editor, The Feynman Lectures on Physics New Millennium Edition


We wish to express our heartfelt thanks to all who made this book possible, especially:

Thomas Tombrello, Chairman of the Physics, Mathematics, and Astronomy Division, for approving this project on behalf of Caltech;

Carl Feynman and Michelle Feynman, heirs to Richard Feynman, for their permission to publish their father’s lectures in this book;

Marge L. Leighton, for her permission to publish an excerpt from the Oral History of Robert B. Leighton, and problems from Exercises in Introductory Physics;

Matthew Sands, for his wisdom, knowledge, constructive comments, and suggestions on the manuscript—and for his illuminating memoir;

Rochus E. Vogt, for the ingenious problems and answers in Exercises in Introductory Physics, for his interview with us, and for his permission to use them in this volume;

Michael Hartl, for his meticulous proofreading of the manuscript, and for his diligent work with the errata in The Feynman Lectures on Physics;

John Neer, for studiously documenting Feynman’s lectures at the Hughes Aircraft Corporation, and for sharing those notes with us;

Helen Tuck,Feynman’s secretary for many years, for her encouragement and support;

Adam Cochran, for his consummate skill in navigating the swamp of tangled book contracts and personalities to find a new home for this book, as well as for The Feynman Lectures on Physics; and

Kip Thorne, for his grace and tireless work securing the trust and support of everyone involved, and for overseeing our work.