  The coupling of a stringlike fluid with ordinary matter and gravity may lead
to a closed Universe with the dynamic of an open one. This can provide an
alternative solution for the age and horizon problems. A study of density
perturbations of the stringlike fluid indicates the existence of instabilities
in the small wavelength limit when it is employed a hydrodynamic approach.
Here, we extend this study to gravitational waves, where the hydrodynamical
approach plays a less important role, and we argue that traces of the existence
of this fluid must be present in the anisotropies of the cosmic background
radiation.
