By Tim Casey

BOSTON -- During a trip to the East Coast with his wife last month, Alan Nathan walked around Princeton University for a day, the first time he had returned to his alma mater since 1995. After earning his Ph.D. from Princeton, he'd spent more than 30 years as a professor at the University of Illinois, teaching and conducting research on nuclear physics before retiring in December, 2008.

The last time he'd been on Princeton's campus, 18 years ago, he was happy to have made a successful, fulfilling life doing something he always wanted to do since high school. On this visit, 18 years later, he couldn't believe the turn his career had taken.

"I'm coming here with a totally different viewpoint of the world," said Nathan, smiling.

Three days later, Nathan stood in front of a science classroom at Boston University. He seemed comfortable delivering a lecture, as he had thousands of times before. The topic, however -- "Sabermetrics, Scouting and the Science of Baseball" -- wasn't anything he'd envisioned discussing when he began studying physics in the 1960's. The crowd of around 200 listened as Nathan spoke about modern techniques of evaluating hitting. Twelve major league teams had tickets to the weekend seminar, which also featured talks from Red Sox manager John Farrell, former pitcher Brian Bannister and several authorities on the science, scouting and analytics of baseball.

In recent years, Nathan has combined two passions to become one of the foremost experts on the physics of baseball, at a time when the sport has embraced non-traditional insights. He has offered free advice to the Nationals, Cardinals, Red Sox, Padres and Brewers, the only condition being that he can discuss the issues with others in the industry and write about his ideas on his or other baseball websites, in the mainstream press and in academic journals.

In 2011, Nathan spoke with Red Sox executive Tom Tippett about the difference between aluminum and wood bats, discussing new rules the NCAA adopted that year to make the metal bats in college games closer to the wood bats in the majors. Nathan had worked on the NCAA's research panel for several years. The change led to a dramatic decline in college power numbers, and the Red Sox thought Nathan could help them quantify the differences in production.

Nathan has also been a paid consultant for attorneys in baseball injury cases, helping when players get hit by batted balls and lawyers consider suing the bat companies. For him, it's simply a career evolution.

"It's not that [baseball physics] is more fun, it's just that it's different," Nathan said. "I've moved on [from nuclear physics]. It's really a question of moving on. When I was doing experimental nuclear physics, I was having just as much fun. I enjoyed it."

Growing up in Rumford, Maine, 80 miles north of Portland, Nathan rooted for the Red Sox. But unlike smart kids today who dream of becoming the next Billy Beane or Theo Epstein or Andrew Friedman, Nathan had no intention of working in baseball.

In early 1997, Nathan discussed The Physics of Baseball, a book written by Yale professor Robert Adair, as as part of a program sponsored by Illinois's physics department. Nathan hadn't studied the topic much and didn't plan on doing more research. The next day, though, the Champaign (Ill.) News-Gazette ran an article on Nathan's talk, and he was soon getting calls from rotary clubs and alumni associations to give speeches.

During a sabbatical from Illinois a year later, Nathan spent most of his time planning a nuclear physics experiment, but he also read a paper on a dynamical theory of the baseball bat. After analyzing the article, he solved the problem using his own methods and set up a meeting with Adair, who praised Nathan's work. In its November 2000 issue, the American Journal of Physics contained "Dynamics of the baseball-bat collision," the first time Nathan's baseball research had been published.

Nathan since has devoted more time to baseball projects and made a name for himself, especially after the introduction of Sportvision's PITCHf/x in 2006. Marv White, the system's inventor, said Nathan helped him with the flight of the baseball, and to determine if the equations PITCHf/x used were reasonable and dependable. PITCHf/x cameras are now installed in each major league stadium. The system tracks pitches for every game and is found on the MLB Gameday application.

"He's a more than capable physicist," said White, who now works at ESPN, helping them identify new technologies. "His work is quite reliable, and it covers an awful lot of territory."

Major league teams have taken notice. Last month, Nathan met in Washington, D.C., with members of the Nationals front office. They were interested in using the launch speed and horizontal angles at which the ball comes off the bat to evaluate hitting, as opposed to only looking at whether the ball fell in for a hit. They also wanted to know, if there was enough data for individual batters and their swings, would the differences in their swings -- such as the speed, timing or swing plane -- translate to better-hit balls? Nathan said he's fascinated with the topic, but he needs to conduct more research before answering the questions definitively.

Physicist Alan Nathan, Ph.D., talks baseball.
Teams are becoming more open to hiring people with physics backgrounds, including Josh Kalk with the Rays and Mike Fast with the Astros, both of whom were acclaimed writers before joining the clubs. Although Nathan is willing to share his findings, he understands teams want to keep their proprietary information confidential.

"While I'm quite open with [teams], telling them everything I know, they, and rightly so, have to protect their competitive advantage," Nathan said. "If they have developed some technique to do something themselves, they don't want the rest of the major league teams to know about it, because then they'll lose a competitive advantage. It's hard to know, really, what they know and what they don't know."

Nathan's research now mostly centers on the ball-bat collision and flight of the ball. His comprehensive website features much of his work as well as studies from others in the field. He continues to advise the NCAA, too. Baseballs in national college tournaments and most regular season games have raised seams, while major league balls have flat seams, which makes hits carry a longer distance. With Nathan's help, the NCAA is determining whether it should modify the balls to resemble those used in the majors.

Nathan also has spent considerable time evaluating knuckleballs. In a 2012 article for Baseball Prospectus, he analyzed PITCHf/x data from two R.A. Dickey starts and two Tim Wakefield starts during the 2011 season. He found the trajectory for a knuckleball is virtually the same as for any other pitch -- a conclusion that others refute, but Nathan says it's hard to argue with his data. He's trying to obtain more information and high-speed video to better understand why the knuckleball seems to break in a random direction, and why, if the pitch does have a smooth trajectory, there's an illusion that it's not smooth.

His work will be featured in the 2014 Hardball Times Annual. He realizes that for all the fun he had teaching, researching and writing about nuclear physics, his new subject area has received much more attention than he ever coveted.

"For sure, it's true that the number of people who have read my baseball writings, the things that I've written about baseball, is far, far greater than the number of people who have read my nuclear physics articles," Nathan said. "Far, far greater. There's some ego associated with that. It's nice to be liked and everything. I thought I had a pretty successful career as a nuclear physicist. In a way, I've switched careers, and I'm doing stuff that I find interesting and some people even find useful."

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Tim Casey is a freelance sports writer and former Sacramento Bee sports reporter. He works for HMP Communications, a health care/medical media company.