 Bradley Monton (2006) has argued that a specific version of canonical quantum gravity – that with a so-called constant mean extrinsic curvature [CMC] (or fixed) foliation – has the necessary resources to render presentism (the view that all and only presently existing things exist) a live possibility (see the section on Presentism, Eternalism, and The Growing Universe Theory in the entry on  time  for more on presentism). The reason is that with such a fixed foliation one has at one’s disposal some spacelike hypersurface that contains a set of well-defined events that can be viewed through the lens of presentism, such that this set of events at this particular instant (or ‘thin-sandwich’) changes over time. Though he readily admits that CMC formulations are outmoded in the contemporary theoretical landscape, he nonetheless insists that given the lack of experimental evidence one way or the other, it stands as a viable route to quantum gravity, and therefore presentism remains as a possible theory of time that is compatible with frontier theoretical physics. Christian Wüthrich (2010) takes Monton to task on a variety of both technical and non-technical grounds. He rightly questions Monton’s claim that the CMC approach really is an approach to quantum gravity, in the same sense as string theory and loop quantum gravity. It is more of a piece of machinery that is used within a pre-existing approach (namely, the canonical approach). He also questions Monton’s claim, inasmuch as it does constitute an approach of sorts, that it is viable. Simply not being ruled out on experimental grounds does not thereby render an approach viable. Besides, if anything has the prospect of saving presentism, then surely it is Julian Barbour’s position mentioned above. This at least has the added benefit of being a research programme that is being actively pursued.