  On this hyperboloid, a single star (nebula or galaxy, in later  contexts) \(A\), also called “observer” by Weyl,  traces a geodesic world line, and from each point of the star’s world line a light cone opens into the future and fills a region \(D\),  which Weyl calls the domain of influence of the star. In de  Sitter’s cosmology this domain of influence covers only half of the  hyperboloid and Weyl suggests that it is reasonable to assume that  this half of the hyperboloid corresponds to the real world. 