An Illustrated Guide to Relativity by Tatsu Takeuchi

I'm always a little hesitant to post reviews of books that I'm using as reference sources when I'm writing something, because it feels a little like recommending that you skip past my book and go to my sources instead. This is, of course, completely irrational, because however much I my use a given book as a resource, what I'm writing is going to cover a different set of topics, with a slightly different slant. And since the folks at Cambridge University Press were kind enough to send me a review copy of Tatsu Takeuchi's An Illustrated Guide to Relativity, I really kind of owe it to them to, you know, post a review of it.

This book, like many books about physics aimed at non-scientists, grew out of a non-majors course taught by the author at Virginia Tech. The approach to making this a popular level subject in this case, as you can probably guess from the title is to make use of the fact that relativity can be seen as a theory about the geometry of spacetime, and replace all the equations that would ordinarily appear with pictures. These range from little cartoons of smiling stick figures riding in cars and trains and the like to more typical Minkowski spacetime diagrams showing the worldlines of smiling stick figures riding in cars and trains and the like.

While the intro mechanics class that covered relativity back in my undergrad days, twenty-odd years ago now, made use of these diagrams, I didn't find them all that useful, mostly because it's kind of difficult to use them for anything quantitative, and the homework assignments we did were always quantitative. Busting out a ruler to try to figure out the observed length of something in a different frame is more hassle than manipulating the Lorentz transformation equations, at least to me, so I never had much use for the diagrams, and tend not to use them when I teach relativity to physics majors.

The graphical approach is pretty much ideal for a general-audience treatment, though, because the diagrams do lend themselves to qualitative treatments. Takeuchi's cartoons and diagrams are charming, and there's roughly one page of pictures for every page of text, so this really is a graphical approach to the subject. Takeuchi walks the reader through the development of the key idea of the constancy of the speed of light, and sets up the later diagrams really well.

As a result, the book does an absolutely terrific job of getting the conceptual ideas of relativistic kinematics (dealing with measurements of distances, speeds, and times) across. The discussion of things like length contraction and the twin paradox is just about the clearest I've seen anywhere. I've borrowed a number of things from this approach for the book-in-progress, and may even try to work some in to the majors class the next time I teach it.

The graphical approach is not as successful with relativistic dynamics (force, momentum, and energy), because the relevant quantities are much more abstract, and their graphical properties are not as immediately obvious to a reader who is unfamiliar with them. I would be very interested, though, to see this approach extended to General Relativity, as a cheery little stick figure seems to promise on the final page. General Relativity is a wholly geometric theory, and the pictorial approach could potentially be a huge help there.

Anyway, I definitely recommend the book for anybody interested in getting a sense of how relativistic kinematics works, and learning to calculate some simple properties in a relatively (heh) painless way. If you're a physicist teaching a non-majors course, I would definitely recommend looking at it as a possible text. It could even be useful in thinking about how to approach the subject in an early course in the physics major sequence.

This book is an outstanding example of how to present a highly mathematical subject in a non-mathemtical way without "dumbing it down." I've learned a lot from this book, and recommend it to anyone who wants to know more about the basics of relativity, or how to write science for a non-scientific audience.