Schrödinger's cat is a thought experiment created by Austrian physicist Erwin Schrödinger in 1935 illustrating what he saw as Copenhagen's interpretation of quantum mechanics applied to everyday objects. This scenario presents a hypothetical cat that can be simultaneously alive and dead, a state known as quantum superposition, as a result of being linked to a random subatomic event that may or may not occur.

Thought experiments often appear in theoretical discussions in various branches of physics, including quantum mechanics.

In our case, a cat is kept in a box, together with a Geiger counter. There is a small amount of a radioactive substance, so small that, perhaps within an hour, one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube is discharged and, through a relay, releases a hammer that breaks a small flask containing hydrocyanic acid. If this whole system is left isolated and closed for an hour, it could be said that if the Geiger counter detected a decay, the cat will have died, but if there was no radioactive decay, then the kitten will be still alive!

So, after one hour, when the box is open, the probabilities of finding the cat alive or dead are the same and equal to 0.5.

Since Schrödinger's time, many interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat about how long quantum overlays last and when they collapse, if they do.

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