Today's Google Doodle Celebrates the 135th birthday of Max Born, the physicist and mathematician who discovered one of the most important rules in quantum mechanics.He's best known for the Born Rule, a theory that uses probability to predict the location of a particle in a quantum system. That's important for understanding and using quantum mechanics, the principles that govern physics at subatomic scales. We rely on quantum physics for all sorts of things, from precise timekeeping to better encryption.Before Born, physicists assumed that if you wanted to know the location of a quantum particle, you had to measure it exactly using a series of physical experiments and a lot of unwieldy calculation. Born figured out that all you really needed was a matrix (a group of numbers lined up in columns and rows) and the rules of probability.The basic idea is that you can calculate the odds of finding the particle at any particular location. For the mathematically inclined, here's how that works: every particle has an equation called a wave function, which describes how the particle's behavior changes over time (if you want to see an example, check. One of the properties of a wave function is called its magnitude, and if you square the magnitude of the function at a certain point, you get the probability of finding the particle at that location. If you have all the probabilities for a set of possible results, you can get a pretty good idea of what the system is doing without making any direct measurements.If that sounds a little confusing, don't worry. Even other physicists haven't yet figured out how to fully explain why the Born Rule works. They just know that it does.Born won the 1954 Nobel Prize in Physics for his work on quantum mechanics. It also bears noting that, in addition to his significant work on quantum mechanics, he was also the grandfather of singer Olivia Newton-John. Make sure to ponder the mysteries of quantum wave functions next time you listen to the Grease soundtrack.