How are enormously heavy steel ships able to float?
They appear to defy basic laws of nature. But in fact, they're obeying a law of nature, buoyancy, which Greek mathematician Archimedes reportedly discovered while taking a bath. The trick in building ships so that they don't go straight to the bottom is to get the shape right. The vessel has to be configured so that it will be buoyant, displacing a volume of water weighing as much as it does. In other words, if an amount of steel equal to that in a giant tanker were rolled into a compact ball and dropped into the sea, bye, bye ball. But if the metal is spread out over a thousand feet, the ship can cross the ocean.