There is an issue with quantum foam, negative gravity, the cosmological constant, and deSitter Space. The conjecture that quantum foam is the result of complementary virtual particle pairs flashing in and out of existence seems to be consistent with observations such as the Casmir effect. However, while unproven it is generally assumed that both matter and anti matter produce positive gravitation which would result in anti deSitter space-time curvature. The result of this would be the presence of gravitation in a vacuum. This has never been observed and if present would be obvious on a cosmological scale. However, if the conjugate pair production is of positive and negative mass then the gravitation would cancel out. Now consider the consequences of a small bias in the decay rate of these virtual particles where the mean duration of the negative gravity particle was slightly longer than that of its positive gravity counterpart. This may result in the presence of a slight dominance of deSitter space or gravitational repulsion. Assuming that virtual particles with negative gravitation are possible what might be a mechanism for introducing this decay time bias? One possible candidate is the local manifestation of cosmological space time curvature. This would suggest time dilation is subject to S-T curvature which is consistent with relativity. As the universe expands the cosmological S-T curvature would diminish. Consider this in comparison with anomalies in the expansion rate of the cosmos.