Schrödinger’s Smiley :):

To be in two states at the same time – to smile on the outside and be sad on the inside – that’s what this emoticon known as Schrödinger’s smiley means. Its origins can be traced to the thought experiment conducted by Schrödinger to refute the Quantum Mechanics claim about the superposition of two states proposed by researchers in Copenhagen.

Erwin Schrödinger was born in Vienna on August 12,1887 and was awarded the Nobel Prize in Physics in 1933 for his work in Quantum theory. His most well-known work is the Schrödinger equation which describes the behavior of quantum particles which act like both wave and particles.

Schrödinger is most well-known for his thought experiment now known as Schrödinger’s Cat – which he did to refute an idea known as the Copenhagen Interpretation of Quantum Mechanics. It stated that particles could exist simultaneously in two states and that is was only once the particle had been observed that it existed in one state or another.

Schrödinger came up with his thought experiment to argue that the Copenhagen theory did not make sense – the experiment involved a cat in a steel box, some radioactive material, a hammer, and poisonous gas in a jar– when the radioactive material decayed the hammer would get deployed and break the jar which would release the poisonous gas which would kill the cat.

While the box is closed there is an equal probability of the cat being dead or alive – no one knows the outcome until the box is opened. Relating this to quantum mechanics – as long as the box is closed – the cat exists in a superposition of states and is both alive and dead. The sole outcome is observed only once the box is opened. Schrödinger argued that this outcome – the superposition of states is not possible because a cat cannot be both alive and dead.

Ironically his name is associated with the smiley which shows a superposition of both happy and sad states in human emotions. :): The Schrödinger smiley gets its name because of the two contradictory states or the superposition of states it shows – of a person smiling on the outside but feeling sad on the inside.