This famous cat was meant to prove quantum mechanics was absurd — and became its mascot instead

In 1935, physicist Erwin Schrödinger proposed a thought experiment: a cat sealed in a box with a mechanism that has a 50% chance of killing it should, according to the quantum interpretation of the time, remain simultaneously "alive and dead" until someone opens the box and looks.

Schrödinger wasn't proposing this as a description of reality — he meant it as proof that something in the interpretation of quantum theory was broken. A cat is macroscopic, after all, while superpositions are only ever "observed" in labs at the level of single particles.

Nearly a hundred years later, physicists still don't have one universally accepted answer to where exactly the line runs between the quantum world, where superpositions are the norm, and the macroscopic world, where we never see them.

The paradox remains open as an interpretive problem — not because experimental data is missing, but because different schools of physics still disagree about what the mathematics of quantum mechanics actually "says" about reality.