What is string theory? | Space

String theory is the idea in theoretical physics that reality is made up of infinitesimal vibrating strings, smaller than atoms, electrons or quarks. According to this theory, as the strings vibrate, twist and fold, they produce effects in many, tiny dimensions that humans interpret as everything from particle physics to large-scale phenomena like gravity. 

String theory has been held up as a possible “theory of everything,” a single framework that could unite general relativity and quantum mechanics, two theories that underlie almost all of modern physics. While quantum mechanics does very well in describing the behavior of very small things and general relativity works well to explain how very large things happen in the universe, they don’t play nicely together. Some scientists think (or thought) that string theory could resolve the conundrums between the two, conquering one of the major remaining unsolved problems of physics.