EntityQ4780925· pop 6· linked from 17 articlesapparent horizonSign in to savesurface that is the boundary between light rays that are directed outwards and moving outwards, and those directed outward but moving inwardConnectionsMilky WayEntityBlack holeConceptInternational Standard Book NumberEntitygeneral relativityEntitysphereEntitydigital object identifierEntityspacetimeEntityQ180686Entityevent horizonEntityEuclidean spaceEntitybibcodeEntityQ118398EntityHawking radiationEntityCambridge University PressEntityGalactic Center of Milky WayEntityMinkowski spacetimeEntitynormalEntitySchwarzschild metricEntitycompact spaceEntityQ22908627EntityCategoriesMathematics of general relativityPhysical horizonsSpoken articles