The Economist reports on a couple of scientists who will try to perform the Schrödinger cat experiment on living organisms for the first time. I must admit, despite having studied physics for a full year at the university level, I never really grasped the relevance of the Schrödinger experiment. Anyway, it is the first time I’ve seen such an accurate and at the same time brief description of the experiment in the popular press:
[One] of the most famous unperformed experiments in science is Schrödinger’s cat. In 1935 Erwin Schrödinger […], who was one of the pioneers of quantum mechanics, imagined putting a cat, a flask of Prussic acid, a radioactive atom, a Geiger counter, an electric relay and a hammer in a sealed box. If the atom decays, the Geiger counter detects the radiation and sends a signal that trips the relay, which releases the hammer, which smashes the flask and poisons the cat.
The point of the experiment is that radioactive decay is a quantum process. The chance of the atom decaying in any given period is known. Whether it has actually decayed (and thus whether the cat is alive or dead) is not—at least until the box is opened. The animal exists, in the argot of the subject, in a “superposition” in which it is both alive and dead at the same time.
The thing I struggle with, I guess, is Don’t the cat know if it’s alive? Now, what the cat know may be irrelevant for the purpose of the up until now hypothetical experiment. The point is that an object can be in more than one state at the same time. Or, at least it makes the equations add up.