Chaotic Pendulum Chaotic Pendulum contains a deceptively simple set of pendulums in a steel and Plexiglas case. A central T-shaped bar supports three bearing-mounted bars from its ends. The "T” is itself bearing mounted at the intersection of the upright and the cross arm. The visitor gives an initial twist to the pendulums with a protruding knob. Intuition says that the resulting rotation of this system should be, if not simple, at least predictable. Intuition, however, does not work with this device since its motion is chaotic, extremely ~ complicated and long-lived.

Spring Box This piece consists of a large glass cylinder, that is filled with water and tiny glass beads. Here, a stream of water is pumped up through a bed of sand. In fitful spurts, the water bursts from the sand in a meandering eruption that never settles in one place. Sand may seem solid enough when you walk on the beach, but sand with water flowing through it can become a heavy liquid. Natural springs that well up through sand look a lot like what you see here.

Video Feedback The patterns on this monitor are the result of a camera taking a picture that it's showing. Normally, video is a one-way system: a camera gathers information and displays it on a screen. This video system, however, goes two ways: since the camera is pointed at its own monitor, it endlessly loops the image on the screen back in through the lens. Try putting your hand, or some other object, in front of the screen. Tilt up the mirror to make multiple patterns. Notice that even a small change can create a dramatic shift in the pattern 's size, shape, and brightness.

Aeolian Landscape Aeolian Landscape is an exhibit in which a miniature wind-swept desert landscape is recreated by an electric fan and finely ground sand that mimics the process of wind picking up and depositing small particles. Geologists use the term "Aeolian" to refer to land formations that are caused by wind—sand dunes and snow are two common examples. The visitor can change the direction of the fan and notice how the shape of the miniature dunes influencess the pattern of the wind, which in turn influences the shape of the dunes.

Tornado Tornado uses a large mist generator, fans, and a carefully-shaped structure to produce a large tornado. Since the Exploratorium first produced this crowd-pleasing exhibit, it has been duplicated in many museums. Our fourth geneeration version is intentionally de-tuned so that random air currents can cause both the creation of a tornado and its temporary cessation. This latest Tornado is chaotic and unpredictable much of the time; it wanders off the source of the mist, slips out of the grasp of the shearing winds and presents a delightful and ever-changing image.