Can we go further than our 3 approaches to classical BI?
Smolin: dimension, topology, differential structure and signature are fixed in GR and do count as background.
(Wuthrich – some of these (like dimension) aren’t usually thought of as varying between models of GR! … so we need to bear in mind that we’re thinking about a bigger class of GR-like models than we might think.)
So Mark wants to ask if we can create an approach to QG that’s more background independent than GR.