String Theory in a sentence

For example, type IIA string theory is equivalent to type IIB string theory via T-duality, and the two versions of heterotic string theory are also related by T-duality.

String phenomenology is the part of string theory that attempts to construct realistic models of particle physics based on string and M-theory.

In a given version of string theory, there is only one kind of string, which may look like a small loop or segment of ordinary string, and it can vibrate in different ways.

Becker, Becker, and Schwarz 2007, p. 533 Indeed, there have been a number of attempts to identify an inflaton within the spectrum of particles described by string theory, and to study inflation using string theory.

John Schwarz and Joel Scherk came to the same conclusion and made the bold leap to suggest that string theory was a theory of gravity, not a theory of hadrons.

Kapustin and Witten 2007 M-theory main Prior to 1995, theorists believed that there were five consistent versions of superstring theory (type I, type IIA, type IIB, and two versions of heterotic string theory).

Since the simplest models of grand unification have failed, it is now thought by many physicists that inflation will be included in a supersymmetric theory such as string theory or a supersymmetric grand unified theory.

Subsequently, it was realized that the very properties that made string theory unsuitable as a theory of nuclear physics made it a promising candidate for a quantum theory of gravity.

The exact properties of this particle are not fixed by the theory but should ultimately be derived from a more fundamental theory such as string theory.

This theory, like its string theory predecessors, is an example of a quantum theory of gravity.

Unlike supergravity theory, string theory was able to accommodate the chirality of the standard model, and it provided a theory of gravity consistent with quantum effects.

A graviton in perturbative string theory is a closed string in a very particular low-energy vibrational state.

Leonard Susskind had incorporated the holographic principle of Gerardus 't Hooft into string theory, identifying the long highly excited string states with ordinary thermal black hole states.

String theory predicts 1- to 10-branes (a 1- brane being a string and a 10-brane being a 10-dimensional object) that prevent tears in the "fabric" of space using the uncertainty principle (E.

Woit 2006, p. 243 String theorist Leonard Susskind has argued that string theory provides a natural anthropic explanation of the small value of the cosmological constant.

Another issue is that the theory is thought to describe an enormous landscape of possible universes, and this has complicated efforts to develop theories of particle physics based on string theory.

As a result, physicists who study string theory are often guided by physical intuition to conjecture relationships between the seemingly different mathematical structures that are used to formalize different parts of the theory.

Becker, Becker, and Schwarz 2007, p. 6 Unlike in quantum field theory, string theory does not have a full non-perturbative definition, so many of the theoretical questions that physicists would like to answer remain out of reach.

Becker, Becker, and Schwarz 2007, pp. 2–3 One of the main developments of the past several decades in string theory was the discovery of certain "dualities", mathematical transformations that identify one physical theory with another.

Blue arrows indicate T-duality main One notable fact about string theory is that the different versions of the theory all turn out to be related in highly nontrivial ways.