# Wonder of the Day: Dominoes

Dominoes are flat, thumbsized rectangular blocks that can be arranged in straight and curved lines to form designs and games. A domino has one side that is blank, while the other side is marked with an arrangement of dots or pips like those on a die. A typical set of dominoes contains 28 pieces. A player can win a game of domino by scoring points before the opponent does. Some games involve blocking an opponent’s play; others are based on counting the pips on the opposing players’ tiles (a double-blank may count as one or two; a 6-6 counts as 12, for example).

While many people enjoy playing domino in groups, it can also be used to make art, with pieces being set up on a table in a long line and then knocked over, forming an intricate pattern. Some people create elaborately patterned sets, while others build 3D structures such as towers and pyramids.

One of the most popular ways to play domino is by constructing a chain, with each tile being laid down in a row or arc that continues around the table. The first domino must be placed to touch a tile already in the chain that is positioned perpendicular to it and bearing a matching number of spots, called pips, on both ends.

In a game with two players, each person takes turns placing dominoes to form a chain. When a player cannot place a domino, they must pass their turn to another person. A player who has no more dominoes to play can then pick up a sleeping domino from the center of the board and add it to their chain. A game of dominoes may also include positional games in which each player places a domino edge to edge against another so that the adjacent faces are either identical or form some specified total, such as a particular point value.

When the first domino falls, much of its potential energy is converted to kinetic energy, which is transferred to the next domino, and so on, until the whole chain comes crashing down. This type of energy transfer can be a great way to demonstrate the principle of momentum.

Today’s Wonder of the Day was inspired by a question from Juan, who wants to know what the “domino effect” is. The domino effect is a term that was coined by journalist and political columnist Robert Alsop to describe how one event can cause several other events to occur. It is often used to refer to the spread of Communism in Europe during the Cold War, but it can apply to any situation in which a small trigger causes an entire series of events.

Lily Hevesh has been fascinated by dominoes since she was 9 years old, when her grandparents gave her a classic 28-pack. She now makes a living as a professional domino artist, and she regularly posts videos of her mind-blowing creations on YouTube. She follows a version of the engineering-design process to create her setups, and she makes test versions before finalizing a design.