Mathematical Digest

Short Summaries of Articles about Mathematics
in the Popular Press

"Cracking the DaVinci Code," by Keith Devlin. Discover, June 2004, pages 65-69.

In this article, Keith Devlin writes about the number (1 + √5)/2, known tohave been calculated by Euclid around 300 B.C., and more recently referred toas the "divine proportion" or "golden ratio." This value and Fibonacci's famoussequence appear in the recent best-selling mystery, The DaVinci Code, asdo a number of popular misconceptions regarding these mathematical entities.For example, Devlin points out that it's not necessarily true that the Greeksintegrated the golden ratio into their architecture. It's also questionablethat humans, in general, prefer the golden ratio above any other proportion.And why would the ratio of a person's belly-button height to overallheight---which doesn't exactly equal the golden ratio anyhow---be more "divine"than any other ratio of human proportions?

On the other hand, it's true that certain 20th century artists, includingSalvador Dali, used the divine proportion in their paintings. And bothFibonacci numbers and the golden ratio clearly appear in nature: in theposition of leaves around a stem, the number of clockwise and counterclockwisespiral patterns of seeds in a sunflower, or the number of petals on mostflowers. It's a matter of efficiency, as mathematicians and scientists arediscovering.

But regardless of the veracity of the claims surrounding the golden ratio andFibonacci numbers, Devlin notes that people persist in believing these stories.And that's a puzzle that neither he nor the book attempts to solve.

--- Claudia Clark