Dark matter and general relativity

The rotation curve related to the speeds of the stars orbiting close to the edge of a galaxy is flat or slowly rising out to the last measured point. In order to account for this phenomenon, which is inexplicable by the classical theories of gravitation, most astrophysicists postulate the existence of a huge quantity of dark matter in the universe. In the present paper we propose a different approach to this problem without referring to the dark matter hypothesis. We prove that, if the so-called cosmological constant is given a new meaning, then the Einstein equations can account for the observed speeds of the stars in a galaxy.