More than 3

British physicist Stephen Hawking may claim that extra dimensions provide the key to understanding the "grand design" of the universe, but it's Chinese-American mathematician Shing-Tung Yau who actually figured out how those extra dimensions work.

In his new book, "The Shape of Inner Space," Yau and his co-author, Steve Nadis, touch upon the work that led to the discovery of theoretical "Calabi-Yau spaces" — and the cosmic implications of multidimensional geometry. The typical representation of a Calabi-Yau space looks like twisted web of a crumpled-up piece of paper. There's something elegant about its look — in fact, Calabi-Yau paperweights were voted the most popular gewgaw for holiday giving in last year's Cosmic Log Geek Gift Guide contest. But these shapes aren't just abstract art: String theorists believe that every single point in our universe is actually a compactified Calabi-Yau space in six dimensions. Why would they think that? It's because the best theory they've been able to come up with for the universe's grand design requires 10 dimensions to make all the mathematics come out right. Because we can only perceive three dimensions of space and one dimension of time, they suggest that the other six dimensions curled up into near-nothingness when our universe took shape. Yau was the one who worked out the mathematics for the curled-up spaces. At first, he was trying to disprove a conjecture about complex geometry that was proposed by another mathematician named Eugenio Calabi. But then Yau came around to the view that Calabi was actually right, and in 1976 he published the proof that laid the groundwork for the concept of Calabi-Yau spaces. String theorists eventually seized upon the concept in their explanations for the universe's 10-dimensional structure. Later, the theorists threw in an extra dimension to make it 11, because that helped make sense out of five different subtheories. It's that 11-dimensional view of the universe, known as M-theory, that Hawking is touting as the groundwork for the grand design. "The Shape of Inner Space" delves deeply into the math behind M-theory. It also traces Yau's life story, which started with his birth in China in 1949 and and Hong Kong and eventually brought him to Harvard. There are plenty of career highlights along the way: In 1982 Yau won the math world's most prestigious prize, the Fields Medal, for proving the Calabi conjecture. In 2006 he played a role in the tale of Russian mathematician Grigory Perelman's refusal to accept the Fields Medal for proving the famous Poincare conjecture. And Yau is also known for his high-profile criticism of the Chinese educational system and scientific establishment. You can read all about that and more (including Yau's early yen for kung-fu novels) in an extended interview on Discover magazine's website.

further reading