Key points are not available for this paper at this time.
Matter with an equation of state p0ex{0ex}=0ex{0ex}-/3 may arise in certain scalar field theories, and the energy density of this matter decreases as a^-2 with the scale factor a of the Universe. In this case, the Universe could be closed but still have a nonrelativistic-matter density ₀<1. Furthermore, the cosmic microwave background could come from a causally connected region at the other side of the Universe. This model is currently viable and might be tested by a host of forthcoming observations.
Kamionkowski et al. (Mon,) studied this question.