The Basics of Dominoes

A domino is a small rectangular block, sometimes called a bone or a piece, that is used as a gaming object. Usually, each end of the domino is marked with an arrangement of dots like those on dice. These dots are called pips. Most domino sets consist of 28 unique tiles.

The word domino is also used to refer to a game played with these tiles, or to the set of rules that governs the way in which these tiles are to be arranged and placed to form patterns and lines that lead to an ultimate knockout. A domino can be used to create straight or curved lines, grids that form pictures when they fall, and even 3D structures such as towers and pyramids.

Dominoes have been in use for centuries, but the first published reference to a specific design dates from the mid-18th century. Since then, their popularity has increased, and today there are many different kinds of domino games. The most popular are positional games, in which players place dominoes edge to edge against one another so that their exposed ends match (i.e., one’s touch two’s or five’s touch four’s). If the dots on both ends total a multiple of 5, the player is awarded points.

Some modern dominoes are made of polymer, but traditional sets are typically made from natural materials such as bone, silver lip ocean pearl oyster shell (mother-of-pearl), ivory, or a dark hardwood such as ebony with contrasting black or white pips inlaid or painted on them. More recently, there have been domino sets made from marble, granite, soapstone, and other stone; metals such as brass or pewter; ceramic clay; and glass or crystal.

The force of gravity is a key ingredient in the success of any domino effect, says physicist Stephen Morris. “When a domino is standing upright, it has potential energy, or stored energy based on its position,” he explains. But when that domino is knocked over, much of its potential energy is converted to kinetic energy, or the energy of motion. This kinetic energy causes the domino to strike the next tile, knocking it over, and so on.

Despite their relatively simple construction, each domino has a complex interaction with other dominoes and the environment around them. When a domino falls, it can leave an imprint that can affect its neighboring pieces and even the physical properties of the material on which it is resting. These interactions can be studied using mathematical models and computer simulations, or by observing the effects of a domino in action. These tools are increasingly being applied to real-world problems, such as risk analysis of chemical process accidents and earthquakes.