Ever wonder why you can float in a pool? Or how in the world a cargo ship made of heavy steel, carrying many tons of cargo, doesn’t sink? A Greek scientist named Archimedes who lived over 2,000 years ago had similar questions. One of the many things he is remembered for is the Principle of Buoyancy, which explains how objects behave when immersed in a fluid (for example, you, floating in a swimming pool). Today we are going to learn a simple interpretation of this principle which should make it easy to understand why things sink or float.