Bautista, A.Ibort, A.Lafuente López, JavierLow, R.2023-06-172023-06-1720170022-248810.1063/1.4976506https://hdl.handle.net/20.500.14352/17716A new causal boundary, which we will term the l-boundary, inspired by the geometry of the space of light rays and invariant by conformal diffeomorphisms for space-times of any dimension m ≥ 3, proposed by one of the authors [R. J. Low, The Space of Null Geodesics (and a New Causal Boundary), Lecture Notes in Physics 692 (Springer, 2006), pp. 35-50] is analyzed in detail for space-times of dimension 3. Under some natural assumptions, it is shown that the completed space-time becomes a smooth manifold with boundary and its relation with Geroch-Kronheimer-Penrose causal boundary is discussed.Anumber of examples illustrating the properties of this newcausal boundary as well as a discussion on the obtained results will be provided.engjournal articlehttp://aip.scitation.org/doi/abs/10.1063/1.4976506http://aip.scitation.org/open access512.7Geometria algebraica1201.01 Geometría Algebraica