- Guide for self-studying physics created by Susan J. Fowler, updated to second edition in 2021, originally published in 2015.
- Over 600,000 people have used the guide; many pursued physics degrees, others studied out of curiosity.
- Highlights sharing knowledge and serving those unable to study physics formally, underestimated by academic communities.
- Updated version includes new textbook editions, added undergraduate and graduate electives based on reader feedback.