SchrödySchrödinger’s Cat / Quantum Superposition

Schrödy has been in the box since 1935. Nobody has asked her opinion.

Erwin Schrödinger built the box that year, in a paper in Naturwissenschaften, from ordinary parts: a cat, a Geiger counter, a speck of radioactive material so small that in an hour one atom might decay or, just as likely, none might, a hammer, and a flask of hydrocyanic acid. If the counter clicks, the hammer falls. He did not offer it as an experiment. He offered it as an embarrassment: take the quantum rule that a single atom sits in a blend of decayed and not decayed, follow the wiring outward, and the rule seems to say the cat is a blend too.

Look at the first equation on this page and notice what it does not contain. There is no term for a cat that is alive-and-dead on its own. Each cat state is chained to an atom state: undecayed with alive, decayed with dead. That chaining is entanglement, and it is the real content of the thought experiment. Ask about the cat alone and quantum mechanics answers with plain odds, one half and one half, with no interference between them. The strangeness lives in the pair.

Why do real cats never show it? A warm animal trades photons and air molecules with its surroundings at an enormous rate, and every exchange copies a little information about its condition out into the room. This is decoherence, and it hides the interference long before anyone lifts the lid. Whether it also settles which outcome actually happens is still argued.

Schrödinger had shared the 1933 Nobel Prize with Paul Dirac. The cat has outlived most of what was written about it.

Schrödy sits on the lid. Open it if you like. The odds were never inside the box.