Editing Quantum gravity (section)

==== Background independent theories ====
[[Loop quantum gravity]] is the fruit of an effort to formulate a [[background-independent]] quantum theory.

[[Topological quantum field theory]] provided an example of background-independent quantum theory, but with no local degrees of freedom, and only finitely many degrees of freedom globally. This is inadequate to describe gravity in 3+1 dimensions, which has local degrees of freedom according to general relativity. In 2+1 dimensions, however, gravity is a topological field theory, and it has been successfully quantized in several different ways, including [[spin network]]s.{{Citation needed|date=September 2020}}