1,721,004 research outputs found
On a variational theory of light rays on Lorentzian manifolds
No full textIn questa Nota, usando una generalizzazione del principio di Fermat, si studia l'esistenza e la molteplicità di geodetiche di tipo luce congiungenti un punto con una curva di tipo tempo su una classe di varietà Lorentziane, soddisfacente una condizione di compattezza più debole della globale iperbolicita
Geodesics on Lorentzian manifolds with quasi-convex boundary
No full textIn this paper we study existence and multiplicity results of geodesics joining two given events in Lorentzian manifolds with lack of geodesic completeness. The considered Lorentzian manifolds are not necessarily static or stationary and satisfy a condition of convexity on the boundary
Some variational problems in semi-Riemannian geometry
No full textIn this contribution we are concerned with global properties of geodesics on semi-Riemannian manifolds obtained by studying the variational properties of the action functional. Applications to physically meaningful spacetimes in General Relativity will be presented
Fermat Principles in general relativity and existence of light rays on Lorentzian manifolds
No full textApplications of Calculus of Variations to General Relativity
No full textWe present some global results on Lorentzian geometry obtained by using global variational methods. In particular some results on the geodesic connectedness of Lorentzian manifolds and on the multiplicity of lightlike geodesics joining a point with a timelike curve are presented. Such I results allow to give a mathematical description of the gravitational lens effect
On the Existence of Infinitely Many Trajectories for a Class of Static Lorentzian Manifolds like Schwarzschild and Reissner–Nordström Space-Times
No full textSome global properties of static spacetimes
No full textWe show that a static Lorentzian manifold satisfying a completeness assumption is geodesically connected. In particular, such condition is satisfied by all compact static manifolds; in the compact case, we also prove the existence of a closed geodesic in every free homotopy class determined by a finite number of deck transformations
- …
