____________________________________________
“Background-Independence.” General Relativity and Gravitation 43 (2011) 2865-2884.
(published version) [preprint]
Abstract. Intuitively, a classical field theory is background-in- dependent if the structure required to make sense of its equations is itself subject to dynamical evolution, rather than being imposed ab initio. The aim of this paper is to provide an explication of this intuitive notion. Background-independence is not a not formal property of theories: the question whether a theory is background-independent depends upon how the theory is interpreted. Under the approach proposed here, a theory is fully background-independent relative to an interpretation if each physical possibility corresponds to a distinct spacetime geometry; and it falls short of full background-independence to the extent that this condition fails.
Note. The paper is too optimistic about the feasibility of using the size of the asymptotic symmetry group of a theory as a measure of the degree to which it falls short of full background-independence. This can't work: sometimes strengthening the asymptotic boundary conditions of a theory leads to s a theory enlarges its asymptotic symmetry group and sometimes it reduces it in size—on this point, see pp. 1079 and 1090 ff. of Ashtekar and Romano, “Spatial Infinity as a Boundary of Spacetime.”
_____________________________________________