SCHRODINGER’S EQUATION IS DEAD AND ALIVE

Perhaps better known in popular culture for his cat,

Erwin Schrodinger

(pictured) was a Nobel Prizewinning physicist who was in at the beginning of quantum theory.

His equation acts as quantum mechanics’ equivalent of

Newton’s second law—the one that goes force = mass x acceleration.

Newton’s law predicts how a physical system will move over time, and so

Schrodinger’s equation does the same for an isolated quantum system. Given a known set of initial conditions, it can predict the evolution of the wave function of a system, making it useful in quantum chemistry.

Schrodinger’s

Cat is a thought experiment, please don’t try to carry it out, you’ll only end up with an unhappy cat and possibly some unwanted attention from the FBI. He came up with the idea during a discussion with Einstein, in an attempt to point out what he saw as problems with quantum mechanics.

It goes like this. You have a box from which no radiation can escape. In the box, you place a cat (although any small mammal would do), a vial of poison gas, and a lump of unspecified nuclear material. The chance that the nuclear material will release a particle that will penetrate the vial, release the gas, and kill the cat is about 50/50. Once you seal up the box, you have no way of knowing

(it’s a very docile cat, apparently) what has happened until you open it and observe the state of the system. Therefore, while the box is closed, the cat can be said to be in a superposition— both alive and dead at the same time.

This was intended to poke fun at the Copenhagen interpretation of quantum physics, the prevailing view at the time—if the cat survives, it remembers nothing of being dead, so at which point did this superposition happen? These days, it’s arguably more famous than its author, thanks to its inclusion in novels, poetry, TV, games, and movies.