Superstrings. Computer illustration representing superstrings. The superstring theory is a Theory of Everything" (or "Grand Unification Theory") which seeks to unite gravity as a force along with the other fundamental forces (electromagnetism and nuclear forces). The theory states that fundamental particles such as quarks and electrons are not points of energy or matter, but result instead from the vibrations of infinitely long but infinitely thin "string-like" entities on a far smaller scale."