Watching the dice fly gracefully through the air, staying perfectly together with a nice backspin, is a beautiful thing. If beauty and grace meant the casino paid us more, we’d be set. Alas, they don’t even care. All that matters is the number the dice show when they stop. In that case, what difference does a backspin make? The answer: Angular Momentum makes all the difference.

This discussion is complements of the Division of Dynamics, Technical University of Lodz, Stefanowskiego 1/15, 90-924 Lodz, Poland, where four Polish Graduate students published the paper, “The Three-Dimensional Dynamics of the Dice Throw”.

For a sniper, angular momentum is a big help in getting a bullet into a distant target. A rifle barrel is engraved with a precision spiral, forcing a bullet to spin when it exits the barrel. Because of the angular momentum of the spinning bullet, no amount of wind or gravity will prevent the bullet from striking the target with the pointy end first.

Just like angular momentum of a spinning bullet is a sniper’s friend, spinning dice is the Advantage Player’s friend. Take a look at the attached drawing. Look for the spin axis (black arrow), the angular speed (speed of the spin, the blue arrow), and the angular momentum (the green arrow).

For the Advantage Player, the spin axis is horizontal and perpendicular to the forward movement of the dice through the air. With sufficient spin (more spin gives more angular momentum), your dice will resist wobbling – unintended list and yaw (Naval terms. Yaw is when the bow, or front of the ship, moves right or left. “List” is when a ship leans right or left). This means your dice are much more likely to strike the table and continue straight forward, with no crazy jaunt to the side.

Of course, a good “back”spin also slows the dice down when striking the table, by somewhat opposing the forward momentum of the dice – a separate, but important, factor in skillfully thrown dice.

In short, without the angular momentum of a good backspin, dice are much more likely to strike each other and bounce in different directions – introducing randomness, the enemy of the Advantage Player.

Now, we can discuss the Newton-Euler equations of motion, which are the math behind all this. On second thought, we will leave that to the four Polish students who obviously have too much time on their hands.

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