Legend has it that Isaac Newton had the moment of inspiration that would lead to his theory of gravity when, on a warm afternoon, he saw an apple fall from a tree and wondered why it should fall down ...

An astronaut can hold a tool in space, loosen their fingers, and watch it stay put. Nothing drops. Nothing tugs downward. Yet ...

Among the many functions performed by skeletal muscles, an important one is maintaining our posture. If it weren’t for these muscles, Earth’s gravitational pull may make it difficult for us to stand ...

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. A visualization of how the ...