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Schrodinger’s cat is a thought experiment devised to illustrate what Erwin Schrodinger saw was the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. He found that there was a contradiction with common sense.

Schrödinger’s cat presents a scenario where a cat may be both alive and dead, depending on an earlier random event. The original experiment was imaginary; however similar principles have been researched and used in practical applications. The thought experiment is often featured in theoretical discussions of the interpretations of quantum mechanics.

Schrödinger’s thought experiment [1]

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which much be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small that perhaps in the course of the house, one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges, and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat mixed or smeared out in equal parts. It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy which can then be resolved by direct observation. That prevents us from so naively accepting as valid a “blurred model” for representing reality. In itself, it would not embody anything unclear or contradictory. There is a difference between a shay or out-of-focus photograph and a snapshot of clouds and fog banks.
- Erwin Schrodinger, Die gegenwartige Situation in der Quantenmechanik (The oresent situation in quantum mechanics), Naturwissenschaften


[1] Schrödinger, Erwin (November 1935). "Die gegenwärtige Situation in der Quantenmechanik (The present situation in quantum mechanics)".Naturwissenschaften.

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