DGP model

In theoretical physics, DGP gravity is a model proposed by Gia Dvali, Gregory Gabadadze, and Massimo Porrati in 2000 that assumes that a 3-dimensional brane is embedded in a five-dimensional spacetime and addition Einstein-Hilbert term is concentrated near the brane. This assumption makes gravity four-dimensional at short distances and five-dimensional at long distances. The model is popular with the model builders but has resisted embedding into string theory.

It was claimed that it reproduced the cosmic acceleration of dark energy. But some argue that this branch of the theory is unstable. However, the theory remains interesting because of Dvali's claim that the unusual structure of the graviton propagator makes non-perturbative effects important in a seemingly linear regime, such as the solar system. Because there is no four-dimensional, linearized effective theory that reproduces the DGP model for weak-field gravity the theory avoids the vDVZ discontinuity that otherwise plagues attempts to write down a theory of massive gravity.

It has been shown that the combination recent cosmological observations--including SSDS BAO, the CMB and type 1a supernovae--is in direct conflict with the DGP cosmology unless a cosmological constant or some form of dark energy is added. However, this negates the appeal of the DGP cosmology, which accelerates without needing to add dark energy.

• G. Dvali, G. Gabadadze and M. Porrati (2000). "4d gravity on a brane in 5d Minkowski space" (subscription required). Phys. Lett. B485: 208–14.

See also

• Kaluza-Klein theory
• Randall-Sundrum model
• Large extra dimension