Ned Kahn is an environmental artist and sculptor whose work mimics the usually invisible forces of nature and makes it visible to audiences. His main interests include fluid dynamics, optics, acoustics, and other physical phenomena. Kahn worked as an apprentice to Frank Oppenheimer, the founder of the Exploratorium, during the 1980s and designed many timeless exhibits for the institution. He has gone on to design exhibits for museums such as the Museum of Natural History in New York, Museum of Natural History in London, England, the Pasadena Museum of California Art, and others. He has also completed numerous public commissions including works for the Skirball Museum and Cultural Center in Los Angeles, CA and Yahoo Headquarters in Sunnyvale, CA. Kahn is a recipient of the MacArthur Foundation's genius grant.
A fan blows white flakes around inside a 1 meter diameter black cylindrical box with a glass top. The flakes form dunes that move and shift with the wind. Eroding in some places, traveling a while, then being deposited elsewhere, the dunes move. Visitors turn a small wheel that changes the direction in which the fan blows the air. As the air flow changes, the pattern of the dunes also changes. The dunes of plastic flakes in this exhibit show behavior like that of dunes formed by wind blowing over sand and snow. The shape of the dunes influences the pattern of the wind that in turn influences the shape of the dunes.
Angle of Repose
Sand of several different colors and densities falls over raised bumps on an aluminum plate to reveal beautiful patterns. By carefully spinning the disk, observers can create standing waves of continuously falling sand.
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 motion 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.
Circling Wave Umbrella
The fluttering waves that whirl around the edge of the umbrella show how random motion can create a regular pattern. As the fabric spins it forms pockets of swirling air that set it flapping like a flag in the wind. But unlike a flag, this cloth is bound into the shape of a circle. The waves bump into each other as they spin, interacting to create patterns of evenly spaced ripples.
Cloud Rings uses a mist generator and a large rubber membrane with a hole in the middle to launch a ring of vapor up to the ceiling. The ring is generated by the friction between the hole’s edge and the vapor flowing through the hole, which forms a swirling pattern known as a vortex.
Air blowing over the surface of water inside a large Plexiglas hemisphere mimics the action of the wind over the ocean by generating waves. The waves slowly change and build until the entire volume of water is circulating as one wave. Viewers can adjust the speed of the air blower and influence the building of the waves.
A constant stream of air forces a lightweight piece of free-flowing fabric up into the air. The normally invisible air current is suddenly transformed into a colorful visualization of the complexity of the air stream.
Magnetic Field Stone
In this artwork, fine grains of magnetite, a natural form of magnetic ore, move in response to a powerful magnet rotating inside the stone. The particles line up, south pole to north pole, creating jagged spikes that swirl around the center of the bowl. Visitors can push the sand around and watch it pull itself back together, or hold a handful of sand at the bottom of the bowl and watch the sand dance in their hands. The magnetite here was collected locally; in fact, navigational charts sometimes warn mariners for false magnetic readings from San Francisco's magnetite-peppered shores.
Tornado uses a large mist generator, fans and a carefully-shaped structure to produce a large tornado. 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.
Turbulent Orb is a half-meter diameter sphere full of special, colored, flow-visualization fluid. The sphere is mounted on top of a pedestal, it spins on a good bearing. Visitors grasp a metal ring on the pedestal and spin the sphere choosing the direction and speed of rotation. The fluid in the sphere shows swirls and waves of internal fluid motions produced by the actions of the visitors. The turbulence of the fluid in the sphere is reminiscent of the turbulent flows that occur in planetary atmospheres. This exhibit shows the complexities of fluid motion that can be produced by very simple circumstances.
Fog spiraling down into a funnel creates a multilayered vortex which viewers can alter by adjusting the speed of a blower. The exhibit consists of a laminated wood frame base containing a funnel, a fog machine (ultrasonic humidifier), a blower, and an internal spot light.
This artwork features air bubbling up through a fine powder constrained between two glass plates tilted at a 45 degree angle. The tilting creates a continually changing landscape evocative of aerial photographs of river drainage networks on Earth and on Mars. As air is pumped into the powder, it carves small streams. After the initial currents of rising air have carved channels in the powder, subsequent streams follow the paths of least resistance, further deepening and elaborating the drainage network.
Tectonic Basin demonstrates principles of geology, erosion, chaos and more. Fine-grained sand covers a low-frequency vibrating base plate. The vibrations of the plate cause the sand to move and settle in unpredictable ways that resemble the shifting sands of a desert. Visitors can spread the sand with their hands and watch the pattern reform within a few seconds.
SONIC RANGE uses sound to vibrate copper powder, creating a small-scale volcanic landscape complete with rift zones, subducting plates and eruptive fissures.
Settling Column demonstrates that sand falling through water forms complex patterns. The visitor turns a tube of sand and blue liquid over to cause the sand to fall. The angle of the tube affects the patterns of flow. As the sand falls, it displaces water at the bottom of the tube causing the fluid to flow upwards. When this up welling encounters more falling sand, much turbulence is created. The more vertically the tube is oriented, the greater the turbulence and the longer the sand takes to settle.
A one-meter-long pendulum performs a strange chaotic dance. Visitors set a pendulum in motion, yet it does not behave like a simple pendulum because it is tipped with a strong magnet. On the table beneath it are three strong magnets oriented to repel the bob. Visitors position the three magnets about on the table to produce different chaotic paths; they also choose the starting position and speed of the pendulum. The sensitive dependence of motion on initial conditions is a property of chaotic systems. The name Strange Attractor was given to this exhibit because due to arrangements of the three table magnets, the pendulum will come to rest at different locations depending on where and how the pendulum is started.
Visible Effects of the Invisible
Visible Effects of the Invisible graphically demonstrates resonant frequencies. A horizontal, clear glass tube is partially with clear fluid. Sound generated by a speaker housed at one end of the tube causes the air in the tube to vibrate and geysers appear in the fluid where the motion of air is greatest. The geysers are generated at various sections of the tube by the adjusting the resonant frequency of the speaker which causes pressure differentials.
RIFT ZONE uses air bubbling up through fine sand to suggest a small-scale geothermal landscape. By turning a knob, viewers can change the pressure of the air rising up through the sand and alter the shapes and patterns of the landscape. The aerators that activate the sand are arranged in a composition of three elements: a circle, a line and a dot, corresponding to the three kinds of rift zones that occur on earth: solitary volcanoes, fracture zones such as the one spreading on the island of Hawaii, and the ring dike that forms in the crater of a volcano as the central plug cools and then a new eruption occurs around the perimeter in a circle.
Soap Bubbles is a large tray filled with a special soap-solution and equipped with metal hoops of various sizes. With these hoops, visitors can make huge soap bubbles, occasionally big enough to fit over an entire person.
Watch Wind Work
A billboard Ned Kahn designed for the Exploratorium. Small reflective disks on the billboard shimmer with the wind, creating a visual representation of wind's effects on surrounding environments.
Mesocyclone is a 40-foot tall, working model of a hurricane. Powerful fans at the base of the structure create complex airflow patterns. These patterns are made visible by water vapor released from the top of the structure. Untried ever before at this scale, Mesocyclone was a major engineering and design challenge for the Turbulent Landscapes team. The exhibit continues to mesmerize museum visitors, often from quite far away!
Water streaming into a shallow dish creates a large whirlpool. As the water drains, intricate surface waves spiral in and out of the center and the entire vortex begins to slowly oscillate, revolving around the drain. The oscillations grow with each revolution until the vortex is so unstable that it breaks away from the drain and a new vortex immediately forms.