Which 1935 thought experiment introduced the famous cat used to discuss quantum superposition?

Schrödinger’s cat is the 1935 thought experiment introduced by Erwin Schrödinger to discuss quantum superposition.

Schrödinger imagined a sealed box containing a cat, a radioactive atom, a detector, and a poison mechanism. If the atom decayed, the mechanism would kill the cat; if it did not, the cat would survive. Applying a quantum superposition to the radioactive atom appears to produce a combined description involving both outcomes before observation.

Schrödinger proposed the scenario as a criticism of taking a simple microscopic interpretation and extending it uncritically to everyday objects. The thought experiment highlights the measurement problem: how and when do quantum possibilities become a single definite result?

The cat is not evidence that real cats literally remain visibly half-alive and half-dead. It is a conceptual tool for examining the boundary between quantum descriptions and macroscopic experience. Different interpretations of quantum mechanics explain the situation differently, including collapse theories, many-worlds approaches, and decoherence-based accounts.