The Science of Knitting
March 2, 2005A 200-year-old hole in the fabric of mathematics
has finally been mended.
In a recent lecture at The Kitchen theater in Chelsea, a brainy
-- and dexterous -- Cornell mathematician described how she
made a real-life model of a principle that has mystified scientists
for centuries. She crocheted it.
Since the early 1800s, mathematicians have known about something
called "hyperbolic space," but they couldn't figure
out a way to illustrate it. Enter Daina Taimina. After watching
her husband, fellow mathematician David Henderson, make a
rather flimsy version out of paper, she decided to use her
knowledge of handicrafts to create a more durable one. When
her knitted model proved too droopy, she tried crocheting
it with coarse synthetic yarn and the rendering turned out
exactly as she had hoped.
One of the models is now on display at the Smithsonian, and
the scientific community is abuzz with requests for her handicrafts.
So what is hyperbolic space? "The easiest way of understanding
it is that it's the geometric opposite of a sphere,"
Taimina says. "On a sphere, the surface curves in on
itself and is closed. But on a hyperbolic plane, the surface
is space that curves away from itself at every point."
Still confused? That's where her models come in. Verbal descriptions
are so hard to understand that, until recently, only a small
group of mathematicians really knew what it all meant. And
even they overlooked naturally occurring examples, like some
kinds of lettuce and seaweed.
Now, using the crocheted models, fifth graders are learning
about hyperbolic planes. Neurosurgeons also find the models
useful because the planes' surface is similar to that of the
brain. Henderson says scientists speculate that this kind
of folding allows the brain to store information and retrieve
it more quickly than if the surface were stretched out flat.
Even cartoons can benefit from the models. Pixar animators
use this kind of geometry to make certain surfaces, like fabric
and skin, appear three-dimensional on screen.