Extra Dimensions is a new blog written by Andrew Grant, the online editor at Physics Today. In his posts he’ll offer fresh perspectives on recent developments in physics and the related sciences. He’ll also explore the physics behind events in the news—beginning with the start of baseball season.
Thank goodness for LIGO, the Laser Interferometer Gravity-Wave Observatory. Not only did the discovery of gravitational waves there send ripples of excitement through the physics community, it also brightened one of the toughest stretches of the year: the two-month gap between the Super Bowl and the start of baseball season.
Mercifully, Opening Day arrived last week. To celebrate the annual restart of America’s pastime, I contacted Alan Nathan of the University of Illinois at Urbana-Champaign, who studies the physics of baseball. The field is experiencing a sort of golden age, due in part to advanced technology such as Statcast, a system of cameras and radar equipment that can track the speed of the bat, the route of a fielder, and the spin of a curveball. From research by Nathan and others, here are three nuggets of conventional baseball wisdom that have been proven wrong by physics:
- Watch the ball from the pitcher’s hand to the bat. Just because hitters can track the entire flight of the ball, which takes a mere 400 ms, doesn’t mean they can react to it the whole way. Scientists had long figured that was the case, Nathan says, but a new study proves it. Japanese researchers set up a pitching machine and had college players take swings while wearing a special set of glasses. For some pitches, the glasses would go dark 150 ms after the ball left the pitching machine, which left hitters blind to most of the ball’s approach. Other times, the glasses would darken 150 ms before the ball reached home plate, which gave hitters a good look at all but the final approach. Although performance suffered when the players lost sight of the ball’s early trajectory, they seemed to do fine when they missed out on just the last moments of flight. “Any new information obtained in the last 150 ms is useless,” Nathan says. “The body can’t react.”
Todd Frazier follows through on a home run swing—with no hands on the bat. Image Credit: James Garvin
- Get a good grip on the bat to make solid contact. The key to getting a hard hit is good bat speed and squaring up the ball. It turns out that once batters achieve that, their grip during contact makes no difference. The bat–ball interaction lasts for about 1 ms, Nathan says, and sends vibrations propagating up and down the length of the bat. By the time those waves rebound off the hands of the batter or off the knob of the bat and return to the point of contact, the ball is gone. The implication: Hitters can release the bat just before contact without affecting the result. Then-Cincinnati Reds third baseman Todd Frazier demonstrated this counterintuitive concept in May 2012, when he hit a home run essentially by throwing the bat at the ball.
- Swing down on the ball to hit farther. This is a case where players’ understanding of physics works against them, Nathan says. By swinging downward, the idea is to hit the ball with backspin, which helps the ball carry farther. But Nathan says the benefit of backspin pales in comparison with the disadvantage of having to line up a sinking bat with a ball that, due to gravity, is also sinking. The smarter approach is to swing slightly upward, roughly aligned with the trajectory of the ball. That strategy also provides a greater chance of success if the swing is slightly early or late. Nathan’s advice: If you want to get on base, swing upward at a 5° to 10° angle; that will lead to line drives and maximize the acceptable margin of error for timing the bat’s arrival in the hitting zone. Home run hitters should aim for a 25° to 30° angle.
Although I’m doubtful these physics-approved tips would have prolonged my baseball career (it sadly fizzled at age 12), they are paying dividends for some pros: Cole Figueroa, a career minor leaguer, earned a spot on the Pittsburgh Pirates roster after studying up on the physics of his swing. With Statcast providing a wealth of information about every pitch and swing, prepare to hear a lot more about teams exploiting physics to maximize success on the field.
