Star Quotient

Every week on the CBS crime series "Numb3rs," another chalkboard-filling calculation helps find a serial killer, solve a kidnapping or thwart larceny. On the show, the numbers are crunched by Charlie Eppes, a math professor at fictional CalSci played by heartthrob David Krumholtz. In real life, CalSci is a close facsimile of Pasadena's own Caltech and the computational heavy lifting is being done by the show's math consultant, Professor Gary Lorden, the head of Caltech's math department. We quizzed the professor about what it's like bringing his passion for statistics and probabilities to the masses. And yes, there's going to be math.

OK, how many decimals of pi can you give me?

A few years ago, I memorized it to 15 or 20 places, I think 3.1415926. I'm not as sure of the last two digits. I know some mathematicians who have memorized a couple thousand digits of pi just for fun.

In real life, how applicable is mathematics to actual crime-solving?

It's not only solving crimes. It's looking for terrorists. It's trying to make cryptography work in both directions, have your messages not [be] stolen by somebody else and stealing somebody else's messages. The National Security Agency hires more PhD mathematicians than any university or Microsoft or any of those other companies.

But would your average gumshoe be using number theory?

A lot of crime is corporate, white-collar crime that involves huge databases. I'm consulting now for a firm whose service is to look at millions of documents in some sort of corporate fraud case and find the ones that need to be delivered to the other side, or that need to be looked at by prosecutors. And that would be true in crime investigation.

What formula do you think of as having star quality?

If I wanted to do a hit list, Kim Rossmo's formula for defining the hot zone in a serial attacker. That's applied math. At the other end of the spectrum, my colleague Dinakar Ramakrishnan put down some formulas characteristic of what's called the Riemann Hypothesis, formulas defining the Riemann zeta function, and Euler's Product. Those formulas are some of the most beautiful things in number theory.

What makes a formula "elegant," a word that often is used on the show?