Donald E.Knuth CSLI Publications, Stanford, Calif., 2001. $35.00 (257 pp.). ISBN 1-57586-327-8

Many physicists know Donald Knuth as the creator of TeX, which has revolutionized the way we communicate scientific results. Some will know that he is a distinguished computer scientist, one of the giants of the field. But few will know that he is also a devout Lutheran, who has thought deeply about how his academic discipline informs his religious beliefs.

Very few highly regarded scientists are religious, in the sense of believing in a personal God, even though surveys show that close to 90% of the US population believes in God. In a random sample of scientists, roughly 40% say they believe, a percentage that has remained unchanged for over 80 years. But only 7% of members of the National Academy of Sciences profess such a belief. (See E.J. Larson and L. Witham, Nature3941998313 https://doi.org/10.1038/1.28478 https://doi.org/10.1063/1.28478 ). While a number of conclusions might be drawn from these figures, the relevant one in this case is that Knuth is not typical of scientists as eminent as he is.

In 1999, Knuth gave a series of six lectures at MIT as part of the “God and Computers” project. Things a Computer Scientist Rarely Talks About is a written version of those lectures and includes the questions and answers that followed each lecture. Knuth’s tone throughout is modest. He does not claim to have “… solutions to problems that have challenged and baffled the best human minds for thousands of years.” Rather, he describes various projects and analyses he has carried out to expand his religious understanding, projects only a computer scientist would undertake. For example, to deepen his understanding of the Bible, Knuth employed statistical sampling. Rather than start at Genesis and see how far he could get, he analyzed in depth chapter 3, verse 16 of each book of the Bible. This allowed him to get a pretty good idea of the Bible’s scope without a lifetime of study. From Knuth’s book, you can learn how to make your own translation of the Bible even if you don’t know any Hebrew or Greek. You probably won’t have the clout to commission world-famous calligraphers to prepare beautiful renditions of each of your verse translations, as he did, but you can read about that project here too. (Aesthetics has played an important role in Knuth’s work, especially his work on typesetting. Unfortunately, however, the small black-and-white images of the calligraphy in this book are rather disappointing.)

The most engaging parts of the book are the fascinating tidbits you encounter along the way. Here are some examples:

  • The reason Knuth is listed in the Guinness Book of World Records.

  • Why Knuth thinks users of the Emacs editor have more free will than users of Microsoft Word.

  • The proposal to Knuth by computer scientist Edsger Dijkstra that the SLAC accelerator should run for only an hour at a time; it should then be shut down so one could think about the results for a year before restarting the machine.

  • The appropriate scorn Knuth heaps on people who claim to have found hidden messages in the numerology of biblical texts. He points out that applying similar techniques to the license agreement for the Microsoft Access Developers Tool Kit has yielded equally dramatic prophesies.

  • Knuth’s years of frustration at reading popular accounts of quantum mechanics, after which all became clear when he read P. A. M. Dirac and discovered that, “Apparently, when physicists talk to physicists, they talk about linear transformations of generalized Hilbert spaces over the complex numbers.”

Knuth has an interesting take on the question of whether God is finite or infinite. Knuth is perfectly happy with a finite God. Being finite isn’t much of a limitation, given an appreciation of the immense size of finite numbers, such as Super K, that Knuth discusses.

Despite many enjoyable passages, the book ultimately disappoints. While I can imagine that the lectures might have been wonderful to listen to, their verbatim transcription to the printed page does not always work well. A large fraction of the lectures centered around Knuth’s study of selected verses from the Bible, but the written version comes across as repetitious, with many uninteresting details. Knuth’s analysis of the verses is not deep and not particularly informed by a scientific sensibility. And too many of the questions in the question-and-answer sessions were superficial and could have been edited.

Things a Computer Scientist Rarely Talks About is a unique book. Ultimately its charm lies in the author’s approach to the subject rather than what he actually finds in the end. As Knuth himself writes, in discussing the purpose of life, “The important thing to me … is not the destination, but the journey.”