Throughout history, people have used many methods to clean their teeth. Some ancient people chewed on frayed twigs. Others rubbed their teeth with cloth or swabbed them in vinegar. The Egyptians may have been the first people to use toothpaste when they mixed powdered pumice (a porous rock formed in volcanic eruptions) with vinegar and applied it to their teeth in the 100's B.C. Some toothpastes still contain pumice, but science has since supplied other toothpaste ingredients that the ancient Egyptians never dreamed existed.
A sonic boom occurs when a vessel breaks the speed of sound. So what is this infamous sonic boom, if not the shattering of the picture-window-in-the-sky?
About 90 percent of Americans consume some form of caffeine every day: It's our most popular drug by far. What's so special about this stimulant?