d3o

Here at PopSci, we love when our leading-edge reporting on the seemingly unbelievable, futuristic developments in science and tech end up, well, becoming reality. We reported three and a half years ago on d3o, the elastic polymer that's flexible at rest but stiffens instantly in response to an impact, first found in a soft winter beanie that protects like a helmet. Now, it can be found in 107 products made by 22 different companies, ranging from iPod cases to polo kneepads.

Imagine a shoe so uncomfortable you have to hammer the insole and smash it inside a door to make it tolerable. Now imagine tossing the same $70 shoe in the trash because it shredded into pieces after just 45 minutes. Welcome to the world of ballet.

In its raw form, d3o looks like slime and molds like Play-Doh, but take a hammer to a clump and it changes to a stiff rubber. This curious substance introduced itself in the 2006 Olympics as a safety lining for the Spyder skiing suits, and that same year, d3o's protective ski hat won PopSci's Best of What's New Award.