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How a Little Science Goes a Long Way in Baseball


Barry Bonds’ 71 home runs in a single season or Clayton Kershaw’s ability to strike out 301 batters in one year may seem like magic to most of us.

While we enjoy the sense of wonder we feel witnessing these talents, not everyone is satisfied to simply sit back in astonishment. Understanding the science behind baseball’s greatest players and their feats adds to our enjoyment of the game. Read through these points to gain a deeper appreciation of how players leverage the laws of physics to optimize their performance and wow fans.

Baseball & the Science Behind Energy Transfer

Each spring when training begins, reporters across the country ask University of Illinois physics professor Dr. Nathan to discuss the science of baseball. The most common questions include: How can a ball duck or swerve so dramatically at the last minute? How do batters choose where to put the ball?

But is Dr. Nathan a sports physicist? Not by a long shot.

Dr. Nathan has spent his career studying the collision of sub-atomic particles. Like baseballs, these particles rotate on an axis at varying speeds and with varying rotations. Interestingly enough, his findings about sub-atomic particles relate directly to the science of baseball. His answers to the following questions make sense and make baseball far more calculated and complex than it can appear.

Why Is the Bat’s Sweet Spot So Important?

Players share that when the ball hits the sweet spot on the bat, it feels awesome, powerful, even “true.” From their experience and from their physical sensations in their hands, they know a ball hit on the sweet spot has the greatest chance of going far and in the intended direction.

Physics makes the thrill of the sweet spot clear. First, understand that the bat is not a rigid object. Watch any slow-motion replay of a great hit. If the ball connects on the sweet spot there isn’t much bat movement. If the ball hits above or below the sweet spot, the bat vibrates, even to the point of hurting the player’s hands.

The energy and momentum of the ball transfers to the bat, causing a violent collision. If it hits where the bat can best deflect the energy, that energy transfers back to the ball, sending it in the opposite direction with the most force. If the ball hits higher or lower than the sweet spot, much of its energy transfers to the bat. This is what makes the bat vibrate. Therefore, at the sweet spot, you get the most pop.

How Do Pitches Change Course at the Last Minute?

The goal of the batter is to estimate where the ball will be when it crosses home plate. He does this by watching the ball as it leaves the pitcher’s hands, but at about twenty feet away the batter can no longer process the movement of the ball. His vision and decision-making capacities cannot keep up with the ball’s speed. Therefore, it’s critical for the pitcher to throw the ball in a way that makes it change course in those last twenty feet.

Pitchers can make the ball drop, rise, and veer left or right by manipulating speed, rotation (spin), and the axis around which the ball spins. Dr. Nathan has determined that, due to the laws of movement and momentum, a small motion put on the ball at the beginning of the throw continues to build throughout the ball’s trajectory. This small movement can be nearly undetectable to the batter. And the more unpredictable a pitcher you are, the more strikes you achieve.

How Do Batters Direct Balls to an Intended Spot on the Field?

It’s not only the pitcher that puts spin on a ball. The batter, too, can make a ball harder to catch. Excellent batters can determine whether to put top spin or bottom spin on a ball, depending on the goal they want to achieve that inning. They put top spin on a ball by hitting it with the top of the bat so that it torques downward. The long grounder causes the infielders and outfielders both to scramble. The batter may choose to put a bottom spin on a ball to force the ball upward for a pop fly or even a foul. The energy from the ball hitting the bat off-center creates friction which can even lead to burning the ball. Even though the ball maintains contains contact with the bat for only one-thousandths of a second, it’s a violent energy transfer.

Why Do Bats Break in the Middle Rather Than Where the Ball Makes Contact?

When the ball hits the bat outside of the sweet spot, the bat bows or vibrates drastically. The outside wood fibers stretch, feeling the most stress where the most dramatic arc occurs — in the middle of the bat. The ball may have initiated the bend, but it didn’t cause the wood fibers to break. It’s the bend, not the ball itself that breaks the bat.

Scientists reverse engineer what baseball players learn from muscle memory and experience. Still, knowing some science of baseball could help both players and fans respect the game and its intricacy.