If you’ve ever watched a domino set-up, or even just played with one yourself, you know that the beauty of a perfectly crafted line of dominoes cascading to fall is something to behold. But a little-known fact is that these amazing displays, and the games that can be played with them, also demonstrate a fundamental principle of physics.
Dominoes are small, flat, rectangular blocks used as a gaming tool or for marking and counting. The most common types of domino are white and black, with each having a different number of spots or dots (also called pips) on the face. These markings, molded or drilled onto the surface of each tile, originally represented the results of throwing two six-sided dice. The absence of any marks, or blanks, on a domino, indicated zero. Today, dominoes are made of various materials, including wood and plastic, and come in many colors and designs.
While there are many different games that can be played with a domino set, most involve positioning a tile edge to edge with another so that the numbers on the two matching ends of the domino match. Then the players take turns playing additional tiles into this chain, with each tile being positioned so that it touches only one end of a previous tile (called a double). The resulting chain, often referred to as a “snake line”, develops according to the whim of the players.
The number of dominoes in a typical set ranges from double-six to double-nine, with progressively larger sets containing more and more unique combinations of ends. The most popular extended domino sets include double-nine, double-12, and double-18, each of which provides a maximum number of matching end faces of 12 or more. Occasionally, very large sets of dominoes, such as double-21, exist, but they are not usually used for play.
Like a deck of cards, the identifying markings on the surface of a domino are known as pips. The same markings, which originally represented the number of dice that were thrown to determine a combination, are still used in some domino games to identify the particular number of each domino. In addition, some dominoes have a line across the face which divides it into two square halves. Each half contains an arrangement of pips, or blanks, and the absence of pips indicates zero.
Physicist Stephen Morris explains that when you stand a domino upright, it stores some energy — its position — in the form of potential energy. When you knock over the domino, however, much of this energy is converted into kinetic energy, which causes the domino to tumble. This process is similar to what happens in a chain reaction, which is the basis of domino games. It’s also the same underlying principle that allows Hevesh to create her massive installations. Watch the video below to see how she uses physics to create her intricate layouts.