  The problem of bringing quantum theory and general relativity together in a single theory remains unsolved. (See Quantum Gravity.)  There are many contenders, notably string theory and loop quantum gravity. One of the issues that has been raised is that the hole argument has shown us that no successful theory of quantum gravity can be set against an independent, container spacetime. John Stachel was an early proponent of this outcome of the hole argument. See Stachel 2005 (Other Internet Resources). This issue has often been raised by loop quantum gravity theorists specifically as a criticsm of string theoretic approaches, for string theoretic approaches have such a background spacetime. See Gaul and Rovelli (1999) (Other Internet Resources) and Smolin (2005) (Other Internet Resources).