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String vibrations. In physics, a string is a physical entity postulated in string theory and related subjects. Unlike elementary particles, which are zero-dimensional or point-like by definition, strings are one-dimensional extended entities. Researchers often have an interest in string theories because theories in which the fundamental ...
String theory is a broad and varied subject that attempts to address a number of deep questions of fundamental physics. String theory has contributed a number of advances to mathematical physics, which have been applied to a variety of problems in black hole physics, early universe cosmology, nuclear physics, and condensed matter physics, and ...
String theory is a branch of theoretical physics that attempts to build a theory of quantum gravity using one-dimensional strings rather than zero-dimensional point particles as fundamental building blocks. The name string theory is somewhat of a misnomer since the modern theory also includes higher dimensional objects known as branes
Edward Witten (born August 26, 1951) is an American theoretical physicist known for his contributions to string theory, topological quantum field theory, and various areas of mathematics.
Brian Randolph Greene [1] (born February 9, 1963) is an American physicist known for his research on string theory.He is a professor of physics and mathematics at Columbia University, director of its center for theoretical physics, and the chairman of the World Science Festival, which he co-founded in 2008.
As its name suggests, heterotic string theory combines elements of multiple versions of string theory to attempt to create a more realistic explanation of elementary particle physics. This work was part of a series of advances that forestalled the predicted merger of cosmology and fundamental physics. [6]
Note that in the type IIA and type IIB string theories closed strings are allowed to move everywhere throughout the ten-dimensional space-time (called the bulk), while open strings have their ends attached to D-branes, which are membranes of lower dimensionality (their dimension is odd - 1,3,5,7 or 9 - in type IIA and even - 0,2,4,6 or 8 - in type IIB, including the time direction).
At low energies, type IIA string theory is described by type IIA supergravity in ten dimensions which is a non-chiral theory (i.e. left–right symmetric) with (1,1) d=10 supersymmetry; the fact that the anomalies in this theory cancel is therefore trivial.