And that’s the way the cookie crumbles...

The CBS drama “NUMB3RS,” a show about utilizing math in difficult crime scenes, recently featured the formulas of David Finn, Associate Professor of Mathematics. The series of mathematical formulas was displayed on a recent episode. Finn’s work was used particularly in scene where the mathematician Charlie Eppes explained how math can be used in the baking of cookies, justifying his skills as a cook to his female confidant and colleague. “I’m using differential geometry to perfect the chocolate chip cookie,” Eppes says.

“The formula explains how the cookie spreads once placed on the cookie sheet. The cookie starts out with a ball of dough, then flattens out as air releases,” explains Finn. So why would such a formula be developed? “When hired to be a professor, we give [lectures] to show we can teach. I was baking cookies one day and I wondered,

‘Why do they form that way? Why do they take on that particular shape?’,” says Finn.

The mathematical model was derived from the manipulation of parametric equations that model the surface of the cookie and its curvature shape. Partial differentiation and analysis of wetting energy also brought Finn to the model.

However, the model is not completely accurate, “Everything is still being researched, but if the dough is stiff, such as a vanilla wafer, then it is a pretty good approximation,” Finn states. The formula is mostly accurate while cookies are baking, but the cooling effects on cookies after removing them are being researched as an undergraduate project.

Finn regularly watches the show, but says he does not relate much to the character Charlie Eppes, “There are your mathematical geniuses who work at MIT and Caltech to research new [methods], and then there are those who just like to teach, like me.” The show demonstrates the connection of complicated mathematical concepts and the real world, even in the simple process of cookie baking. At the same time, math can be equally or more fulfilling in the humble occupation of teaching.