Schrodinger’s cat is one of the most famous thought experiments in all of science. The source of countless jokes, t-shirts, and pseudo-intellectual conversations. The idea is this: if a cat is put into a box with an elaborate quantum booby trap then when we open the box the trap will either be activated and kill the cat or not be activated at all. Quantum Physics says the cat should be in “superposition” while we are not looking at it, just like the rest of the quantum system. Meaning the cat is both alive and dead at the same time until we look at at! Zombie cat!

Incredible! Except, Schrodinger didn’t mean that at all.

Erwin Schrodinger, quantum physicist extraordinaire, devised the thought experiment as a way to show how the Copenhagen Interpretation of quantum mechanics, the mainstream one, must be wrong. Pointing out that that we cannot think of a cat as both alive and dead at the same time, but if the interpretation tells us this is the case, then it must be incorrect.

Albert Einstein, who was never completely comfortable with much of quantum mechanics, also agreed, writing to Erwin: “You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gunpowder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.”