  Matter with an equation of state $p=-\rho/3$ 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 $\Omega_0<1$.
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.
