title: Blood out of a stone.
abstract: Almost 50 years ago, astronomers provided evidence for powerful radio emissions localized in two giant "lobes" on opposite sides of elliptical galaxies. These lobes are now known to be powered by jets emanating from black holes at the centers of the galaxies. In his Perspective, Blandford discusses how the black hole may generate the jets. He highlights the report by Koide et al., who have simulated one mechanism for supplying the jets with energy via a magnetic connection to the gas just outside the black hole's event horizon.
authors.affiliation: Division of Theoretical Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA. rdb@caltech.edu
authors.forename: R D
authors.initials: RD
authors.lastname: Blandford