image Allison Filice for Quanta Magazine

**Schrodinger’s Cat **^{[1]}

a life or death

logical miscatsception ^{[2]}

observed ^{[3]}

for Halloween ^{[4]}

^{[1]} Schrödinger’s cat: a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor (e.g. Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while in the box, the cat is simultaneously alive and dead, a superposition, and this state can be described by a mathematical wave function. Yet if you look in the box the cat is either alive or dead not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other.

^{[2]} “All that is solid melts into air, all that is holy is profaned, and man is at last compelled to face with sober senses his real conditions of life, and his relations with his kind.” Communist Manifesto Marx and Engels

^{[3]} “In any physical system, without observation, you cannot say what something is doing. You have to say it can be any of these things—even if the probability is small.” – Eric Martell, Millikin University

^{[4]} If two particles are generated so that their quantum states cannot be separated they are described as entangled. A “spooky paradox” (Einstein) occurs if the entangled particles are now separated by millions of miles and a measurement is made on one particle. That measurement seems to be instantly transmitted to the other particle.