How sadly appropriate that we should have to say goodbye to the brilliant physicist Stephen Hawking on National Pi Day. Like Einstein before him, Hawking has changed the way we view the cosmos in ways most of us still don’t fully comprehend. Even physicists who can “do the math” are still trying to work through the deepest aspects of Hawking’s theories. For those of us who can’t do the math, it’s perhaps enough to recognize the genius of the author of A Brief History of Time and his impact on our understanding of the workings of the universe (or multiverse). So raise a slice of your favorite pie today, in honor of the brief history of Stephen Hawking.