http://xxx.lanl.gov/abs/gr-qc/9903084

Gerard t'Hooft, 'Quantum Gravity as a Dissipative Deterministic System', Classical and Quantum Gravity v16 (1999), p3263:

'It is argued that the so-called holographic principle will obstruct attempts to produce physically realistic models for the unification of general relativity with quantum mechanics, unless determinism in the latter is restored. The notion of time in GR is so different from the usual one in elementary particle physics that we believe that certain versions of hidden variable theories can -- and must -- be revived. ...'

Hidden variables (http://en.wikipedia.org/wiki/Hidden_variable_theory) are an attractive approach, but not determinism. Determinism to me means the ability to mathematically produce an exact solution to a problem. This cannot be done in quantum mechanics where you have the uncertainty principle or wave equation, even if the basis for the uncertainty and wave equation are explained by a causality (chaos created by orbits in a three body system, because the mutual interactions continuously change the plane of orbit and so on; as soon as you fire a particle at a hydrogen atom to probe it you have a three body situation, with the probeing particle affecting the orbit of the electron around the proton).

I've taken a look through t'Hooft's paper. It does not look very exciting. For example, there is a section dealing with viscosity. I don't see why viscosity is of interest for a continuum model. We know that viscosity implies drag force, and that the continuum does not behave like this, and that it just resists accelerations (inertia, Newton's 1st law).

I don't see what information loss and quantum computing or the entropy of the black hole have to do with understanding quantum gravity. Perhaps I'm just plain stupid.