Any of a number of theories in particle physics that treat elementary particles (see subatomic particle ) as infinitesimal one-dimensional "stringlike" objects rather than dimensionless points in space-time .
Different vibrations of the strings correspond to different particles. Introduced in the early 1970s in attempts to describe the strong force , superstring theories became popular in the 1980s when it was shown that they might provide a fully self-consistent quantum field theory that could describe gravitation as well as the electromagnetic forces. The development of a unified quantum field theory is a major goal in theoretical particle physics, but inclusion of gravity usually leads to difficult problems with infinite quantities in the calculations. The most self-consistent superstring theories propose 10 dimensions; 4 correspond to the 3 ordinary spatial dimensions and time, while the rest are curled up and not perceptible.