It’s not often that a sophisticated scientific thought experiment makes it into the cultural lexicon, but if one ever had cross-over appeal, it’s “Schrödinger’s Cat.” Erwin Schrödinger, the Austrian physicist who came up with the paradox (and, I might add, one of the darkest LOLCatz images of all time) in 1935 as part of his Nobel-winning work in quantum mechanics, would have celebrated his 126 birthday today, and the geeky folks at Google have marked the occasion with an appropriately feline doodle.
Though it has been subject to a number of tweaks over the years (Einstein famously preferred gunpowder to hydrocyanic acid as the method of cat execution), the thought experiment goes roughly like this: A cat is kept in an opaque container along with some poison, a Geiger counter, and some radioactive material. If an atom of the material decays, the counter detects it and releases the poison, killing the cat. Because of the amount of the material in question, there is a 50/50 chance that this will or will not happen over the course of an hour. We can only know the “true” result, of course, by looking in the container.
While this description may sound rather straightforward, the “Copenhagen interpretation” of quantum mechanics suggests that the situation is far more mysterious than it seems. Simply put, before we look in the box, the theory suggests that the cat is both alive and dead. In the language of physics, the two “versions” of the cat exist in a “superposition,” a blurry combination of all possible states, until our observation forces it to “collapse” into one state or another.
It’s important to note that Schrödinger found this result “quite ridiculous” and intended his thought-experiment as a way of showing the limitations of interpretations of quantum phenomena, especially beyond the subatomic realm. Physicists have grappled with the scenario ever since, proposing alternate interpretations including most notably the “many worlds” version that suggests that both cats exist, not in the same container, but in distinct universes created the moment we open the lid.