## MatheMUSEments

Articles for kids about math in everyday life, written by Ivars Peterson for Muse magazine.

## May 12, 2007

### Unfolding Wonders

A collapsible umbrella looks downright simple next to one of Chuck Hoberman's amazing unfolding toys. His most famous toy is the Hoberman sphere—a geometric ball of plastic struts and pivoting joints. At the touch of a finger, it magically unfurls from the size of a basketball to a latticework sphere large enough for a toddler to sit inside. Just as readily, it shrinks back to its compact form.

As an artist, engineer, architect, and inventor, Hoberman spends a lot of time thinking about simple geometric shapes—circles, triangles, spheres, and so on. Like a magician, he is fascinated by the notion of making something vanish, then suddenly reappear, and he loves the idea of one shape smoothly transforming into another. He has a passion for designing things that not only look interesting but also act in a surprising way.

Hoberman's mother was a children's book author and his father an architect. As you might expect, he played with building blocks, Lincoln logs, and Erector sets when he was young. But he says he preferred drawing and painting. He spent hours with his brother making comic books. An art teacher at school made him aware of how important it was to observe carefully and draw exactly what you see.

In college, he was given the assignment of making a sculpture that moved and came up with an artwork made of plastic sheets that unrolled to reveal interesting patterns. That got him interested in how gears, levers, pulleys, struts, and cables work together in mechanisms, and he studied mechanical engineering to learn more.

Early in his career, Hoberman worked at a robotics company, where he learned how to use computers for design and to work with machinery. On his own, he explored different ways of folding origami-like paper constructions into compact units. He then moved on to metal and plastic structures that could balloon into surprisingly large forms.

Hoberman now holds several patents for ways of packing large structures into small spaces. He has used those ideas not only to create ingenious toys but also to make practical items, including a briefcase that collapses to the size of a book, a portable tent made from a single sheet of fabric, and medical devices that can sneak into tight spaces.

You can see large-scale versions of his unfolding structures at several science centers, including the Liberty Science Center in Jersey City, New Jersey, and the California Science Center in Los Angeles. Photographs of these and other Hoberman creations can be found on the Web at www.hoberman.com.

One of the most spectacular of Hoberman's creations was a latticework aluminum arch 36 feet tall that stood earlier this year on the stage at the Olympics Medals Plaza for the 2002 Winter Olympics in Salt Lake City. His arch opened like the iris of an eye, revealing the stage.

To Hoberman, math is not just numbers or formulas on a page. Math is about shapes and relationships among shapes—which he makes beautiful, surprising, and fun.

Muse, July/August 2002, p. 34.

Images: Hoberman