Someone recently asked on my little office whiteboard what theory I wish I had come up with. I'm still not sure whether they were being cheeky or not, but I took the question seriously. Because, well, why not? Also, it gave me the chance to talk about one of my favorite old-timey physicists: James Clerk Maxwell. If you haven't heard of him, look him up. Outrageously brilliant. Deeply insightful. Fantastically bearded. The trifecta.
One of his big contributions to the world of physics in the late 1800's was the discovery of light. I mean, everyone knew that light existed, but Maxwell was the first to figure out what it was: waves of electricity and magnetism. And he didn't stop there. In 4 compact equations, he was able to unite three different realms of cutting edge (well, for the nineteenth century) physics: electricity, magnetism, and light.
Let that sink in for a bit. The magnets on your fridge, the battery powering your smartphone, and the light from distant stars are explained by the same simple principles. That feat of unification - of finding a single overarching theory to describe a wide swath of the natural world - doesn't happen often.
In a battle between Einstein and Maxwell, I'm betting Maxwell every time.