Cosmological consequences of high-frequency oscillations of Newton’s constant

We show that high-frequency, small-amplitude oscillations of Newton's constant G can dramatically alter cosmology even if the frequency is very high compared to the expansion rate. For example, it is possible to have a spatially flat universe in which dynamical tests of {Ω}==(matter density)/(critical density)---tests which attempt to directly measure the mass density of the universe---obtain values less than unity ({Ω}==0.1--0.3, say). The cosmological effects can be obtained in a frequency-amplitude range allowed by all known constraints on G and its time derivative.