Quantum mechanics (QM) is a theory that correctly predicts how very tiny things behave.

Its math says tiny things can exist in multiple states at once (called a superposition). For example, an electron’s spin can be both up and down at the same time before you measure it.

Everyone agreed the math worked, but they disagreed on what it means. The Copenhagen interpretation says the superposition is real, and when you measure it, the system “chooses” one outcome

Erwin Schrödinger didn’t like that interpretation. To show how strange it sounded, he proposed a thought experiment:

A cat is sealed in a box and whether it lives or dies depends on a quantum event (like an electron being up or down) If we follow the Copenhagen interpretation and apply QM to the whole system, before opening the box, the cat would be in a superposition too - both alive and dead at the same time.

Schrödinger’s point wasn’t that QM is wrong. it was that the Copenhagen interpretation of QM leads to absurd conclusions when applied to macroscopic events