Local covariance and background independence

Understand

One of the many conceptual difficulties in the development of quantum gravity is the role of a background geometry for the structure of quantum field theory.

• To some extent the problem can be solved by the principle of local covariance.
• The principle of local covariance was originally imposed in order to restrict the renormalization freedom for quantum field theories on generic spacetimes.
• It turned out that it can also be used to implement the request of background independence.