超弦理论

grand unified theory \grand unified theory\, grand unification
theory \grand unification theory\n. (Theoretical physics)
Any of a class of physics theories that attempts to explain
the electroweak forces, stong force, and gravitation within a
single mathematical conceptual scheme. In the 1990's {string
theory} and {superstring theory} were prominent examples.
Abbreviated GUT, plural GUTs.
[PJC]


string theory \string" the`o*ry\ (str[i^]ng" th[=e]`[-o]*r[y^]),
n. (Physics)
A mathematical theory for describing the properties of
fundamental particles, which represents the particles as
one-dimensional string-like objects, which exist in the
normal four dimensions of space-time plus additional
dimensions, the total dimensions being ten, eleven, or
twenty-six depending on the version of the theory. The
properties of fundamental particles in string theory and
their manner of interaction with each other depend upon the
modes of vibration of the strings[17]. The attractiveness of
this theory rests in part on its ability to provide a unified
treatment of gravity as well as the three other basic forces
of nature, in a manner consistent with quantum mechanics. The
great difficulty of doing the calculations required by the
theory, however, has thus far (1999) made it impossible to
calculate the observable properties, such as the mass, of
known particles, such as the electron, proton, mesons,
quarks, and neutron; thus there is as yet no experimental
verification for the theory. The most popular version of the
theory depends on a mathematical property called
supersymmetry, and the theory derived form this principle is
properly called {superstring theory}, a term which is often
used interchangeably with string theory. See also string[17].
[PJC]