August 29, 2020

Forging Links Between Mathematics and Art

Science News, June 20, 1992

To many people, art and mathematics appear to have very little in common. The seemingly rigid rules and algorithms of mathematics apparently lie far removed from the spontaneity and passion associated with art. However, a small but growing number of artists find inspiration in mathematical form, and a few mathematicians delve into art to appreciate and understand better the patterns and relationships they discover in the course of their mathematical investigations.

To prove the remarkable fruitfulness of such links, more than 100 mathematicians, artists, and educators gathered last week at the Art and Mathematics Conference (AM '92), held in Albany, N.Y. Organized by mathematician and sculptor Nat Friedman of the State University of New York at Albany, the meeting represented his attempt to find people with whom he could share his deep interest in visualizing mathematics, whether in geometry, sculpture, computer art, or architecture.


Attempts to visualize such mind-bending mathematical transformations as turning a sphere inside out without introducing a sharp crease at any point during the operation demonstrates how mathematics and computer graphics can lead to valuable insights that are potentially useful to both scientists and artists.

In 1959, when Stephen Smale, a mathematician at the University of California, Berkeley, first proved this particular operation possible, no one could readily visualize how it happens. By gradually simplifying the steps involved in turning a sphere inside out, mathematicians eventually found ways of picturing the entire process.

François Apéry of the University of Upper Alsace in Mulhouse, France, has now captured the essence of the process, known as a sphere eversion, in a surprisingly simple model. Imagine a globe marked with an equator and lines of longitude, or meridians, that connect the poles. At the start of the sphere eversion, as one pole moves toward the other, the meridians twist sideways more and more.


François Apéry demonstrating the essence of his model of a sphere eversion at the AM '92 conference.

When the poles meet, the meridians twist so much that they flip like a wind-blown umbrella over the coincident poles to double up into a smaller spherical shape having an open end marked by a ring showing the new position of the original sphere's equator. The twisting continues until the equator closes up into a point and the meridians overlap and cross each other. At this stage, the sphere's outside becomes its inside, completing the eversion.

Apéry speculates that the first half of this sphere eversion may serve as a mathematical model of the way an embryo, starting off as a ball of cells, can pull in part of its outer wall to form a cavity among its dividing, differentiating cells. Biologists call the process gastrulation.

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