Relativity Visualized by Lewis Carroll Epstein
This short book is filled with diagrams and illustrations, as the Visualized in its name would imply. That’s important and useful for the following reason which I first heard from Sanjoy Mahajan: The visual system in animals has been developing from some years while our more abstract experience with symbols has been around for maybe years. There’s a full thousand-fold greater evolutionary lineage in our visual hardware than in our symbolic hardware. The take home message is “Pictures are usually better than equations.”
Now, the great number of visualizations is very useful for conveying ideas and developing intuition, but it does not qualify as mathematical proofs that would enshrine the logical foundations of relativity theory. But that’s fine; Epstein didn’t set out to write a relativity textbook. Instead, this is like a relativity (both special and general) intuition primer and is quite useful in that regard. The usual stumbling blocks people (like me!) run into are addressed, so he clearly knows his audience.
One downside I’ll point out is the sometimes baffling ordering of the figures. I’ll turn the page and have no idea where I’m suppose to be looking first. Even with the order discerned and the figures examined, relativity remains a non-intuitive topic for the upstart student and so repeat readings will almost certainly be required.
Another unique feature of Relativity Visualized are the arts and crafts he urges you to do, such as making spacetime diagrams on cones to show where gravity comes from. Even if you don’t perform them yourself, the illustrations do a pretty good job of showing what it would look like if you did. I can imagine a future where I’m trying to explain relativity to someone, and falling back on these suggestions to illustrate point.
All in all, a great place to start to get the feeling for one of the pillars of modern physics, and a good springboard to a more advanced textbook (there are perhaps three or four equations in this book, but are extremely simple).