This is the month in which Nobel Prize winning physicist Erwin Schrödinger was born (August 12, 1887). On his birthday, I found myself wondering about the english idiom, "curiosity killed the cat" along with Schrödinger's famous thought experiment - explained well in the above video, and summarized by the New York Times in this way:
In 1935, hoping to make some sense of one of the paradoxes of quantum theory -- in which subatomic stuff can act like both waves and particles and be in more than one place at a time -- the great Austrian physicist Erwin Schrodinger proposed a famous thought experiment. We are asked to imagine a cat trapped in a box with a glass vial of poison. Nearby lies a chunk of radioactive material, like uranium. If an atom of the uranium decays, an electronic detector will trip a hammer that smashes the vial and kills the cat.
Now according to a cherished tenet of quantum mechanics, uranium atoms, unlike marbles or baseballs, cannot be said to be in a definite state -- decayed or undecayed -- until they are observed. Before that, the atoms hover in a quantum limbo, stuck in both possible states at the same time.
Here's what Schrodinger playfully proposed: It is only when we open the box and make the observation that the uranium emerges from this netherworld and makes up its mind.
So about the idiom; I wondered with whom it originated, around what time, and how it is typically used today as compared to Schrödinger's remix of the idea that 'curiosity kills.' It appears that the first written documentation of what would become the phrase we know and use today was in a play by 17th century English playwright Ben Jonson in 1598, namely "Every Man In His Humour." This supposed printed inauguration of a variation of the phrase comes from the line "Helter skelter, hang sorrow, care 'll kill a Cat, up-tails all, and a Louse for the Hangman" (Act I, Scene 5). It seems settled that Johnson in his play, meant "care" as in "worry" and not "curiosity" or inquisitiveness. It wasn't until much later (late 1800's) that the actual phrase curiosity killed the cat, was first printed (J. A. Mair's 1873 A Handbook of Proverbs p.34 ) and was taken to mean 'poking one's nose where it does not belong could get one killed.'
It isn't clear how exactly the phrase transformed, but today the idiom is commonly taken to mean that a curiosity-seeker's actions affect him or her adversely. That is, the actor's actions affect the actor, and not a third party. This is different from Schrödinger's thought experiment in that the actor is also affecting a third party, and both parties fates are entangled. As the thought experiment went, until the actor opens the door to the cat-box, the cat is both alive and dead (in a superposition). It is the actor's inquisitiveness that kills the cat, which could or would presumably remain in the superposition indefinitely. Quite a terrible situation for the cat whose life (or lives) lay in the hands of another. Interestingly, in a 2012 Nature publication (also discussed on New Scientist ), it was suggested that the key to not killing or getting killed is "gentle curiosity", or where scientists embody both mob boss and mother.