Dark matter was introduced in order to make General Relativity (GR) compatible 1. with the rotational speed of galaxies 2. and the relative movement of galaxies in local groups. A new study ” has mapped the motions of more than 400 stars up to 13,000 light-years from the Sun. From this new data, they have calculated the mass of material in the vicinity of the Sun, in a volume four times larger than ever considered before. “The amount of mass that we derive matches very well with what we see — stars, dust, and gas — in the region around the Sun,” said Christian Moni Bidin from the University of Concepcion in Chile. “But this leaves no room for the extra material — dark matter — that we were expecting. Our calculations show that it should have shown up very clearly in our measurements. But it was just not there!” Ref: http://www.astronomy.com/News-Obser...ign=ASY_News_NonSub_120427_final&utm_content= Are these results a nail in the coffin of the dark matter hypothesis? Does it imply that General Relativity is invalid on large spatial scales ?