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Explain Schrödinger’s Cat

Erwin Schrödinger

Image credit: NobelPrize.org

Erwin Schrödinger was born on August 12, 1887 in Vienna, and he was awarded the Nobel Prize in Physics in year 1933. He is best known for his eminent work in quantum theory, especially about his thought experiment where a cat was involved to explain the flawed interpretation of quantum superposition.

The Copenhagen Interpretation of quantum mechanics mainly claims that in a physical system, an object can exist in all probable configurations simultaneously, however, observing the system forces it to be collapsed and makes the object go into only one of these possible states. But Schrödinger didn’t think so.

Well, why a cat was involved here? Schrödinger would like to encourage people to imagine that the following objects are inside a sealed container: a cat, radioactive material, a Geiger counter, a hammer and poison. In this system, the amount of the radioactive material was so minuscule that it just had a 50/50 chance of being detected by the Geiger counter during the period of an hour. When the Geiger counter detected radiation, the hammer would smash the poison, resulting in the cat’s death. No one can predict whether the cat is dead or alive until someone opened the sealed container and had the chance to observe the system. Therefore, the cat would exist in some kind of superposition state of being both alive and dead until the system was forced into one configuration.

Of course, Schrödinger noted, that was ridiculous. Quantum superposition can’t work with large objects like cats, because it’s impossible for organisms to be alive and dead simultaneously. Hence, Schrödinger reasoned that the Copenhagen Interpretation must be flawed inherently. Although many people mistakenly assume Schrödinger supported the premise behind his thought experiment with the cat, he actually didn’t. His major point was to claim that it was impossible.

And modern experiments have suggested that while quantum superposition does work with tiny objects such as electrons, larger things should be regarded in a different way.

The following video from Sixty Symbols does a great job in explaining the Schrödinger’s Cat Paradox: