## How Does the Universe Work?

In particle physics the question is asked, "How does the universe work?" This question can be broken into two parts: (1) What are the basic objects? (2) What are the basic forces? In order to understand the reasoning involved with these questions, attempt to solve the puzzle below.

Black figures are observed, while white figures are not observed. The puzzle involves two questions. (1) What are the shapes (basic objects) from which the observed figures are constructed? (2) What are the rules for connecting (basic forces) the shapes? The same two shapes can be used to form both the "observed" and the "not observed" figures. It is the connecting rules which lead to some figures being observed and others not being observed. Remember that you can learn as much from considering what is not observed (white figures) as from what is observed (black figures).

Puzzle adapted from Helen Quinn, "Of Quarks, Antiquarks, and Glue," The Stanford Magazine, Fall, 1983, p. 29 and included in the Topics in Modern Physics, May 1990 and Catching the Sun, 1992, Fermilab.