Stand one domino upright so that when it topples, it hits two other upright dominos, each of which also hits two other upright dominos, and so forth. Arrange as many upright dominos as you can in this fashion so that they fan out as shown in the accompanying photograph. Your challenge will be to arrange the dominos so that every one of them falls. Topple the first domino and observe your chain reaction. Focus your attention on the sound.

This domino chain reaction occurs on a two-dimensional flat surface. What is the dimensional geometry of a nuclear chain? What would happen if a Ping-Pong ball were tossed into a room in which the floor was covered with thousands of set-to-kill spring-action mouse traps? Such an explosive event can be seen by using the keywords “mouse trap chain reaction” for an Internet video search.