Read the full article for free* in Classical and Quantum Gravity:
Local and gauge invariant observables in gravity
Igor Khavkine 2015 Class. Quantum Grav. 32 185019
arXiv:1503.03754
*until 14/10/15

Generalized locality leads to lots of observables in gravity

Igor Khavkine is finishing up his term as a postdoctoral researcher at the University of Trento, Italy. His main interests are mathematical aspects of classical and quantum field theory, with an emphasis on gravity.

The problem of observables in general relativity is essentially as old as the theory itself. Einstein’s guiding principle of “general covariance”, that is, explicit tensorial transformation of basic physical fields and their equations under general coordinate transformations, leads to a formulation of the theory with “gauge” degrees of freedom. Those are degrees of freedom that, simply speaking, don’t contain any physical information and can be arbitrarily altered by the application of a coordinate transformation or, more abstractly, a diffeomorphism. Such a formulation is simple and Continue reading →