You wouldn’t expect the world’s most ambitious cookbook to come from a fellow who acquired PhDs in mathematical economics and theoretical physics from Princeton, then worked with Stephen Hawking on quantum theories of gravity.

While Nathan Myhrvold has a place in business history as Microsoft’s first chief technology officer, his other calling is the culinary kind. “Cooking is a true passion,” he says, as if to explain why a billionaire would spend four years and millions of dollars to create a lavish, six-volume, 2400-page, $625 tome called Modernist Cuisine: The Art and Science of Cooking. It is “the most important book in the culinary arts since Escoffier,” says Tim Zagat, the restaurant guru, in a blurb on the back of the book, which is due out in December.

Myhrvold, 51, has loved to cook ever since his mother allowed him, at age nine, to make Thanksgiving dinner. He recalls that the meal turned out okay. In 1991, when he was creating Microsoft’s research group, Myhrvold competed on a team that won several first place awards at the World Championship of Barbecue. He’s been trained in the culinary arts, but he didn’t seriously consider channeling his passion into a project such as this until 2005. Members of eGullet.com, a culinary site where he’s a regular contributor, suggested he write a book. And he complied.

Myhrvold started hiring in 2007,  housing chefs and scientists and writers in a “cooking lab” that occupies 1,500 square feet of his 25,000-square-foot lab at Intellectual Ventures. The main business of privately-held Intellectual Ventures involves buying patents to help solve big, hairy global problems like malaria. (Myhrvold works with Bill Gates on that.) Meanwhile, the culinary crew went about tackling the problem of explaining modern cooking techniques and the science behind them.

Myhrvold threw himself into the project, experimenting nights and weekends in his enormous home kitchen, writing most of the book himself and taking some of the photographs. He learned plenty. Such as: How long do you have to cook a two-inch steak vs. a one-inch steak? “Roughly four times as long, ” he says he discovered. “It’s the square of the thickness.” The rule, he says, applies to freezing and thawing meats as well.

He decided to self-publish because “I didn’t want to dumb-down the book.” Self-publishing is easier today than ever, he adds. “You can do a deal with Amazon , which we have. Most of the advantages of using an outside publisher have been equalized by technology and the Internet.”

The marketing of  Modernist Cuisine has begun. On Saturday, Myhrvold emailed friends to tell them that the website is up and running. Has his pal Bill Gates seen the book yet? Yes, Myhrvold says. “He told me that it’s the first and only cookbook he’s interested in.”