Bizarre `dark fluid` with negative mass could dominate the universe
(PHYSorg.com Space & Earth)

It`s embarrassing, but astrophysicists are the first to admit it. Our best theoretical model can only explain 5% of the universe. The remaining 95% is famously made up almost entirely of invisible, unknown material dubbed dark energy and dark matter. So even though there are a billion trillion stars in the observable universe, they are actually extremely rare.