The elusive 'Theory of Everything.' A theory that could resolve the most fundamental roadblock in our understanding of how the universe behaves and tie everything neatly up with string. It’s been 50 years since string theory was first proposed, and new work calls into question not only essential parts of the theory itself, but also our working understanding of the universe.
Let’s start at the beginning. We have two primary ways to describe how all the ‘stuff’ in our universe behaves: one big and one small. The first is Einstein's theory of general relativity, which tells us how gravity interacts with space and time to form the world around us. That’s the big.
Then there’s the small: the Standard Model, which works on the quantum level. This says that all matter is made up of building blocks called elementary particles. You can break us down into molecules, then into atoms, then into the subatomic particles like electrons, neutrons, and protons. Smaller still are those elementary particles, divided into two broad categories, quarks and leptons, of which there are different kinds.
But these two theories don’t work together. That’s where string theory comes in.