string theory, description of elementary particles elementary particles, the most basic physical constituents of the universe.

Basic Constituents of Matter

Molecules are built up from the atom , which is the basic unit of any chemical element .
..... Click the link for more information. based on one-dimensional curves, or "strings," instead of point particles. Superstring theory, which is string theory that contains a kind of symmetry known as supersymmetry, shows promise as a way of unifying the four known fundamental forces of nature. The strings are embedded in a space-time space-time, central concept in the theory of relativity that replaces the earlier concepts of space and time as separate absolute entities. In relativity one cannot uniquely distinguish space and time as elements in descriptions of events.
..... Click the link for more information. having as many as 10 dimensions—the three ordinary dimensions plus time and seven compactified dimensions. The energy-scale at which the stringlike properties would become evident is so high that it is currently unclear how any of the forms of the theory could be tested.

Bibliography

See P. C. W. Davies and J. Brown, ed., Superstrings (1988); L. Smolin, The Trouble with Physics (2006).

string theory

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, string 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 weak, strong, and 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 string theories propose 11 dimensions; 4 correspond to the 3 ordinary spatial dimensions and time, while the rest are curled up and not perceptible.

The belief that all physical matter is made up of vibrating elements called "strings." Officially known as "superstring theory," it differs from traditional physics, in which all matter is made up of ball-like particles.