Schrödinger’s Cat

Schrödinger’s thought experiment about a cat illustrates the idea of quantum superposition; until the cat is actually observed it exists in an indeterminate state in which it is both alive and dead. When the box is opened the indeterminate state collapses and the cat is either alive or dead.

In the 'many worlds' interpretation of quantum theory the cat always lives and always dies; two separate universes diverge at the moment when the atom decays.

 

Richard Feynman, one of the world's greatest authorities on quantum mechanics said, "If you think you understand quantum mechanics, you don't understand quantum mechanics".