What’s the difference between a living collection of matter, such as a tortoise, and an inanimate lump of it, such as a rock? They are, after all, both just made up of non-living atoms. The truth is, ...

Imagine a juggler tossing balls into the air. The art of juggling is a dance between motion and pause, where the ball’s speed slows as it ascends, and then quickens on the way down. This dance reveals ...

Speed alone may be the factor that draws many sports fans to the bobsled, luge and skeleton events at this year’s Beijing Winter Olympics. But beneath the thrilling descents of the winding, ...