Composite gravity

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In theoretical physics, composite gravity refers to models that attempted to derive general relativity in a framework where the graviton is constructed as a composite bound state of more elementary particles, usually fermions.

A theorem by Steven Weinberg and Edward Witten shows that this is not possible in Lorentz covariant theories: massless particles with spin greater than one are forbidden. (see the Weinberg-Witten theorem for more details)

The AdS/CFT correspondence may be viewed as a loophole in their argument. However, in this case not only the graviton is emergent; a whole spacetime dimension is emergent, too.

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Theories of gravitation

Standard	Alternatives to GR	Unified field theories	Other
Newtonian gravity (NG) Classical mechanics General relativity (GR) History Mathematics Resources Tests Twistors [S]	Classical theories of gravitation [S] Conformal gravity [S] Scalar theories Nordström Yilmaz Scalar-tensor theories [S] Brans-Dicke Self-creation cosmology Bimetric theories [S] Other alternatives Einstein-Cartan Cartan connection Whitehead [S] Nonsymmetric gravitation [S] Scalar-tensor-vector [S] Tensor-vector-scalar [S]	Teleparallelism Geometrodynamics Quantum gravity Semiclassical gravity Discrete Lorentzian QG [S] Euclidean QG [S] Induced gravity [S] Loop quantum gravity Wheeler-deWitt eqn Theory of everything Supergravity M-theory Superstrings String theory String theory topics	Higher-dimensional GR Kaluza-Klein DGP model [S] Alternatives to NG Aristotle Le Sage MOND Unclassified Composite gravity [S] Massive gravity [S]