Screwy symmetry revealed

Math trick reverses spirals, providing new ways to explore materials

By Devin Powell, 18:20 PM April 8, 2011

Physicists have put a new twist on the humble corkscrew. Just as a butterfly appears identical to its mirror image, objects made of structures that tilt, twist or spiral possess a symmetry now recognized for the first time.

The new discovery is based on a mathematical operation that transforms a clockwise helix into a counterclockwise one, or vice versa.

“Normally, a helix flips when you put a mirror up to it,” says Venkatraman Gopalan, a materials scientist at Pennsylvania State Univers...

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