Falsifiability is a concept from philosophy of science that says that it is possible to prove that a theory is wrong. There are different ways in which can be done. The easiest way to do it is to find an example where the theory should apply, but somehow does not. As an example: Swans are birds related to ducks and geese. Today, several species of swan are known. For most people in Europe, a swan is a large white bird: The only species of swan that occurs in Europe is white. Several hundred years back, people in Europe therefore thought that all Swans were white. In 1697, the Dutch explorer Willem de Vlamingh found black birds that looked like swans, during an expedition on the shores of Swan River, in Australia. Later, it turned out these birds were indeed swans. With his discovery, de Vlamingh had falsified the theory that all Swans were white.