Sakharov observed that many condensed matter systems give rise to emergent phenomena that are analogous to general relativity.
This allows one to create a theory of gravity with torsion from a world crystal model of spacetime in which the lattice spacing is of the order of a Planck length.
[citation needed] According to some prominent researchers in emergent gravity (such as Mark Van Raamsdonk) spacetime is built up of quantum entanglement.
In 1995, Jacobson showed that the Einstein field equations can be derived from the first law of thermodynamics applied at local Rindler horizons.
[6][7][8] In the "quantum graphity" proposal of Konopka, Markopoulu-Kalamara, Severini and Smolin, the fundamental degrees of freedom exist on a dynamical graph that is initially complete, and an effective spatial lattice structure emerges in the low-temperature limit.