Schrödinger's cat

Schrödinger's cat is a thought experiment in quantum mechanics, proposed by the physicist Erwin Schrödinger in 1935. The experiment was designed to illustrate the paradoxical nature of quantum mechanics and the uncertainty principle.

In the thought experiment, a cat is placed in a sealed box along with a radioactive substance, a Geiger counter, and a poison. If the Geiger counter detects a radioactive decay, it will trigger the poison and the cat will die. However, according to quantum mechanics, the radioactive decay is in a superposition of states, both decayed and not decayed, until it is observed. Therefore, until the box is opened and the radioactive decay is observed, the cat is considered to be both alive and dead, in a superposition of states.

The thought experiment is often used to illustrate the concept of superposition and the idea that a quantum system can exist in multiple states simultaneously. It also highlights the role of observation and measurement in quantum mechanics, and the idea that the act of observation can collapse a superposition into a definite state.