What is M-theory in simple terms?
M-theory is a theory in physics that unifies all consistent versions of superstring theory. According to Witten, M should stand for “magic”, “mystery” or “membrane” according to taste, and the true meaning of the title should be decided when a more fundamental formulation of the theory is known.
Has string theory been proven?
And while it’s a potentially powerful idea, which if unlocked would completely revolutionize our understanding of the physical world, it has not ever been directly tested. There have been, however, ways to explore some of the underpinnings and potential consequences of string theory.
How accurate is string theory?
Polchinski explained a computation that shows that string theory is 98.5\% likely to be correct, going on to claim that the probability is actually higher: “something over 3 sigma” (i.e. over 99.7\%). It is sometimes said that theory has strayed too far from experiment/observation.
What is supersymmetry and supergravity?
supergravity, a type of quantum field theory of elementary subatomic particles and their interactions that is based on the particle symmetry known as supersymmetry and that naturally includes the gravitational force along with the other fundamental interactions of matter—the electromagnetic force, the weak force, and …
What is supergravity theory in physics?
In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity; in contrast to non-gravitational supersymmetric theories such as the Minimal Supersymmetric Standard Model.
What are the limitations of super-gravity models?
Supergravity models generically result in an unrealistically large cosmological constant in four dimensions, and that constant is difficult to remove, and so require fine-tuning. This is still a problem today. Quantization of the theory led to quantum field theory gauge anomalies rendering the theory inconsistent.
What is the supersymmetry of gravity?
Since the supersymmetry (SUSY) generators form together with the Poincaré algebra a superalgebra, called the super-Poincaré algebra, supersymmetry as a gauge theory makes gravity arise in a natural way. Like any field theory of gravity, a supergravity theory contains a spin-2 field whose quantum is the graviton.
When was the first model of supergravity created?
The first model of four-dimensional supergravity (without this denotation) was formulated by Dmitri Vasilievich Volkov und Vyacheslav A. Soroka in 1973. The minimal version of four-dimensional Supergravity was constructed in detail in 1976 by Dan Freedman, Sergio Ferrara and Peter van Nieuwenhuizen.