EntityQ4669818· pop 7· linked from 6 articlesabsolute horizonSign in to saveboundary in spacetime, defined with respect to the external universe, events inside which cannot affect an external observerConnectionsFriedmann–Lemaître–Robertson–Walker metricEntityReissner–Nordström metricEntityAlbert EinsteinPersonBlack holeConceptStephen HawkingPersonInternational Standard Book NumberEntityDavid HilbertEntityHenri PoincaréEntityJ. Robert OppenheimerPersonspecial relativityEntitygeneral relativityEntityHendrik LorentzEntityKurt GödelEntitydigital object identifierEntityspacetimeEntityRoger PenroseEntitySubrahmanyan ChandrasekharEntityQ12998EntityHermann WeylEntityArthur EddingtonEntityCategoriesConcepts in astrophysicsGeneral relativityPhysical horizons