String Theory

String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything (TOE), a self-contained mathematical model that describes all fundamental forces and forms of matter. String theory posits that the elementary particles (i.e., electrons and quarks) within an atom are not 0-dimensional objects, but rather 1-dimensional oscillating lines ("strings").

The earliest string model, the bosonic string, incorporated only bosons, although this view developed to the superstring theory, which posits that a connection (a "supersymmetry") exists between bosons and fermions. String theories also require the existence of several extra dimensions to the universe that have been compactified into extremely small scales, in addition to the four known spacetime dimensions.

The theory has its origins in an effort to understand the strong force, the dual resonance model (1969). Subsequent to this, five superstring theories were developed that incorporated fermions and possessed other properties necessary for a theory of everything. Since the mid-1990s, in particular due to insights from dualities shown to relate the five theories, an eleven-dimensional theory called M-theory is believed to encompass all of the previously distinct superstring theories.

Many theoretical physicists (among them Stephen Hawking, Edward Witten, Juan Maldacena and Leonard Susskind) believe that string theory is a step towards the correct fundamental description of nature. This is because string theory allows for the consistent combination of quantum field theory and general relativity, agrees with general insights in quantum gravity (such as the holographic principle and black hole thermodynamics), and because it has passed many non-trivial checks of its internal consistency. According to Hawking in particular, "M-theory is the only candidate for a complete theory of the universe." Nevertheless, other physicists, such as Feynman and Glashow, have criticized string theory for not providing novel experimental predictions at accessible energy scales.

Read more about String TheoryOverview, Basic Properties, Testability and Experimental Predictions, Gauge/gravity Duality, History, Criticisms

Other articles related to "string theory, theory, string":

Light Cone Gauge - String Theory
... In string theory, light-cone gauge fixes the reparameterization invariance on the world sheet by where is a constant and is the worldsheet time ...
String Theory - Criticisms - Background Independence
... A separate and older criticism of string theory is that it is background-dependent — string theory describes perturbative expansions about fixed spacetime backgrounds ... Although the theory has some background-independence — topology change is an established process in string theory, and the exchange of gravitons is equivalent to a change in the background ... like many quantum field theories, much of string theory is still only formulated perturbatively, as a divergent series of approximations ...
Superstring Theory - The Mathematics - D-branes
... D-branes are membrane-like objects in 10D string theory ... as occurring as a result of a Kaluza-Klein compactification of 11D M-theory which contains membranes ... Because compactification of a geometric theory produces extra vector fields the D-branes can be included in the action by adding an extra U(1) vector field to the string action In type I open string ...
Louise Dolan - Biography
... physics and her contributions to string theory have included symmetries in the Type II superstring and integrable structures in super conformal non-abelian ... Her work has revolutionized string theory, and she is considered to be the one of the originators of the field ... a Department of Energy grant, which funds the string theory program at Chapel Hill ...
Stanley Mandelstam
... relations were a central tool in the bootstrap program which sought to formulate a consistent theory of infinitely many particle types of increasing spin ... Mandelstam, along with Tullio Regge, did the initial development of the Regge theory of strong interaction phenomenology ... Along with the double dispersion relation, Regge theory allowed theorists to find sufficient analytic constraints on scattering amplitudes of bound states to ...

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