Erwin Schrödinger's famous thought experiment at last safe for cat-lovers. An uncrushed hat awaits the foot of fate. When a particle decays, the foot crushes the hat. But the probability of that particle decaying within an hour is 50%. At the end of the hour, is the hat crushed or uncrushed? The Copenhagen interpretation of quantum mechanics tells us that, if no-one observes the hat, the hat is neither determinately crushed nor determinately uncrushed. It is, in fact, in a "superposition" of the two states (crushed and uncrushed). This picture illustrates that strange condition. Schrödinger thought this was absurd, and therefore a decisive reason to reject the Copenhagen interpretation.