A quickly poured beer or soda can create a layer of foam -- also known as a "head" -- toward the top of the glass. But while a soda head rapidly disappears, a beer head lingers even after you've begun to drink the beer. How can this be possible?
No one can dispute that Albert Einstein is one of history's greatest thinkers. Although he isn't really known as an inventor, his ideas formed the basis for some of the greatest inventions ever devised. Here are a few of the man's most revolutionary discoveries.