Bob Jewett studying the physics of pool

Jewett measuring effective pocket size as a function of speed and angle of approach. (Photo by Dave Alciatore)

Bob Jewett's double life

As a high school junior in the 1960s, Bob Jewett (B.S. '75, M.S. '79 EECS) was “one of those nerdy kids who was the lab assistant to the physics class,” he says. Then a friend got a pool table for his birthday and invited him to play; pool was love at first sight. “Each shot was a physics experiment.”  

When Jewett entered Berkeley as a math major, what began as synchronicity turned into conflict. He spent so much time at the Student Union’s 17 billiards tables that he flunked out.

Bob JewettBob Jewett (photo by Jim Block) Jewett then joined the U.S. Air Force. He was sent to school to learn electronics and later stationed in Vietnam, although, he says, “it wasn’t Full Metal Jacket.” Compared to combat zones, the base where he worked with radar weather equipment was a resort, complete with a pool hall, where he became an expert player. After completing his service, he returned to Berkeley and majored in electrical engineering. Bachelor’s degree in hand, he went to work for Hewlett-Packard.

Before long the company had him back at Berkeley, this time underwriting his graduate work. He developed expertise in new fields like data converters based on Josephson junctions, inspired by his studies in superconductivity. Jewett built a distinguished career at HP and its descendants, Agilent Technologies and Keysight Technologies, was awarded five patents in the area of signal generation and analysis and retired in 2015.

Ever since starting over as a Berkeley undergraduate, however, Jewett had been pursuing a parallel career.

The Coriolis Effect

A diagram from Gaspard-Gustave Coriolis's book. Published in 1835, it shows the speed of the cue ball when hit at various heights. It was in 1972 that Jewett came across a little-known book by the 19th-century French physicist Gaspard-Gustave Coriolis, best remembered for analyzing such effects as the opposite spins of hurricanes in the Northern and Southern Hemispheres. His Mathematical Theory of Effects in the Game of Billiards was also about spin: it detailed the behavior of spinning billiard balls.

In the book’s meticulous diagrams, Jewett saw that his sense of pool shots as physics experiments had borne fruit more than a century earlier. “Coriolis figured out a lot of things that people are just now discovering, or haven’t discovered yet,” he says.

In the spirit of Coriolis, Jewett also pursued unexplained phenomena of billiards. Years later, he and a group of colleagues became the first to understand the physics of “squirt,” or cue-ball deflection.

To apply spin, a cue stick’s tip strikes the cue ball off center; hit on one side, the ball travels toward the opposite side, at an often unpredictable angle that can cause a miss. Jewett and his associates, using slow-motion videos, found that as the cue ball starts its spin, the stick is pushed to the side; its momentum is balanced by the equal and opposite momentum of the cue ball itself. Squirt results from conservation of momentum.

The cue stick’s mass near the tip is decisive. Jewett’s personal cue stick is one of the first whose shaft is made of strong, light carbon fiber, greatly reducing squirt. Not to zero. A squirtless stick would have no mass at all.

While simple shots are best, spin is inescapable. Jewett has published numerous articles about shots that depend on spin, having mastered those shots himself.  

Say the target is a ball “frozen” to the end rail, hard against the cushion midway between corner pockets, with the cue ball at the other end of the table. Challenge: send the object ball at a right angle, into the corner. Look impossible? If the player can send the cue ball spinning on its vertical axis to strike the rail immediately beside the target, it will jump sideways, bump the center of the object ball, and knock it straight down the rail into the pocket.

The massé shot is trickier. Assume the object ball sits on the lip of the corner pocket, awaiting only a gentle tap from the cue ball a few inches away. Unfortunately there’s another ball between them. The player strikes from above, aiming the stick directly “through” the cue ball to an imaginary spot on the cloth. If calculated correctly (Coriolis analyzed the relevant geometries in 1835), the spinning cue ball will move away from the obstructing ball, abruptly turn course and stop just after nudging the object ball into the pocket.

The rules of the game

Jewett’s skill in both the performance and analysis of billiards games blossomed alongside his graduate studies, and he began seeking the best way to teach cue sports to others. Players aren’t born experts, and until the late 20th century, learning from pros was rare. Jewett describes most instruction as “Old Joe over in the corner at your local pool hall, who could show you some shots if you’d pay for his time at the table.”

When the Billiard Congress of America created a formal program to train instructors in 1991, Jewett, who’d been teaching since grad school, welcomed the effort. He became a BCA-certified instructor, co-wrote the BCA’s instructors’ training manual and, with two friends, formed the San Francisco Billiard Academy.

His instructional output includes hundreds of articles and instructional videos. He’s the chief editor of the World Pool Billiards Association’s World Standardized Rules. “I’m pretty much into rules,” he says, while admitting that “most champions have never read them.”

The rules and science of billiards may come naturally to an engineer at home with the laws of physics, but Jewett’s mastery goes deeper. In the 1970s, he represented Berkeley in the National Collegiate Championships three years in a row; in 1975, he won the championship.

He hasn’t lost his edge. Last April, at the 2016 US Open Straight Pool Championship in Connecticut, while he didn’t take the top spot, Jewett beat the US champion 125 to 81 in almost two hours of continuous play in an early round.

Careers in pool begin with talent and progress with experience, and early professional instruction is a plus. Theory, however, is optional. “Good players don’t need to know the physics,” Jewett says. “They don’t calculate; they just shoot.”

Bob Jewett’s double life, master of pool and expert engineer, gives him access to a satisfaction denied many: scientific insight into a sport as only a virtuoso can grasp it.