# The Manga Guide to Relativity: Real Relativity, Real Easy!

*Making an intensely complex subject understandable to the non-physicist*

The Manga Guide to Relativity takes an intensely complex subject and makes it understandable to the non-physicist. |

Well, relatively! I didn’t ask to review this book, but my wonderful contact at No Starch Press (read Geeks Anonymous) sent *The Manga Guide to Relativity* thinking that the subject may interest me. After sitting on it for too many months, I finally got around to reading a few pages. After 10 pages, I was hooked.

This volume takes an intensely complex subject and makes it understandable to the non-physicist. And no, it’s not a severely dumbed-down version for the intellectually challenged. Yes, Manga are cartoons, but these are very well-written by several Japanese physics professors and are geared to the interested physics wannabes and those just interested in understanding a very important topic.

As usual, the Table of Contents will give a flavor of what goes on: www.nostarch.com/download/mg_relativity_toc.pdf, with the four main areas of focus being:

• What Is Relativity?

• What Do You Mean, Time Slows Down?

• The Faster an Object moves, the Shorter and Heavier It Becomes?

• What Is General Relativity?

As with other Guides, a story unfolds as, during the closing ceremony prior to summer break at a secondary school academy, the headmaster decides that the class should have a summer assignment studying relativity (subject selected by a spinning prize-wheel). The students scream “Tyranny” at the thought of it, but the head of the student body is “persuaded” to be the sacrificial lamb and take the course so that everyone else can get out of it and enjoy a normal summer vacation! At this point, I should mention that, if you have a chance to peruse this volume, definitely go to page four to see Vice Principal Koromaru — really interesting, and it sets the tone of what is to come: interesting and challenging, but a lot of fun.

The student accepts the challenge, and the physics teacher, Alisa Uraga volunteers to teach him. Luckily for the student, relativity is Miss Uraga’s specialty.

She begins with a very lucid separation of the topic into Special and General Relativity. The distinction lies with ignoring the effects of gravity and acceleration in special relativity. We are then introduced to inertial reference frames and told that, for objects in motion, time slows, length contracts and mass increases. Before the student can raise the objection that this is never seen in everyday life, the teacher quickly explains that these “relativistic” changes are only noticeable at speeds near those of light. And, for those of us who still remember our mass vs. weight confusion, this is also cleared up in a few more pages.

The plot thickens and the story proceeds gradually as we are introduced to the contributions of Galileo Galilei, Sir Isaac Newton and James Clerk Maxwell. The two former are noted due to their descriptions of macroscopic “real life” phenomena (to lull us into a false sense of ease) and the last, to consider his unification of the electronic and magnetic forces (horrors — that means tons of math!).

Actually, anything that could be even remotely construed as challenging is presented as background material in more of a textbook format at the end of each chapter. These sections are only two to 10 pages, captioned with very descriptive titles, and lucidly illustrated by simple diagrams. The diagrams in the first chapter displaying relativistic additions of velocity were particularly helpful to the discussions, as were the descriptive equations that should be simple to master by any high school junior or senior.

The concept of time dilation, examined in Chapter 2 is a bit more of a mouthful. However, rather than resorting to integrals and derivatives, the concept is beautifully illustrated with the Pythagorean Theorem. The twin paradox is used as an example, so that we may consider the consequences of these actions at near-light speeds.

Chapter 3 introduces more characters as the Lorenz Contraction is explained, and we end up with a discussion of the mass/energy interconnection and considering the reason why light must have zero mass.

The last chapter addresses Einstein’s Theory of General Relativity and is an exceptionally nice “contraction” of a very lengthy (and weighty) subject. Here, Miss Uraga admits that, since general relativity is more difficult mathematically than special relativity, she will “superficially” explain the concept. More on inertial frames and introduction to the equivalence principle lead us into inertial forces and, finally, the bending of light by gravity.

At this point, I usually critique the authors for a really lame index. However, as this is not a textbook, I found this feature to be quite adequate and actually helpful.

For those of you purchasing this book, be sure to read the last few pages to reveal the surprise ending! For the secondary student interested in physics and the curious adult wanting to know a little more, this is a great read.

**Availability**The Manga Guide to Relativity, by H. Nitta,

M. Yamamoto, and K. Takatsu. No Starch Press, San Francisco. ix + 177pp (April 2011).

ISBN: 978-1-59327-272-2

• $19.95 Print Book and FREE Ebook (PDF)

• $15.95 Ebook (PDF)

*John Wass is a statistician based in Chicago, IL. He may be reached at* *editor@ScientificComputing.com**.*