Gravity and energy Gravity is what powers the sleds down the ice-covered tracks in bobsled, luge and skeleton events. The big-picture physics is simple – start at some height and then fall to a lower ...

A new study suggests that Lucy, the ape-like human ancestor, died after a fatal fall more than 3 million years ago. A representative model of the 3.2 million-year-old skeleton of Lucy, on display ...