Last month, NASA released two arresting images of black holes. The first: a simulation of how light bends around a black hole surrounded by a glowing disk of infalling matter. The second: an image, gathered by optical, infrared, and X-ray telescopes on Earth and in space, of three supermassive black holes on a collision course.
These images follow a slew of findings that confirm Albert Einstein's model of gravity, from the celebrated Laser Interferometer Gravitational-Wave Observatory (LIGO) detection of gravitational waves to the image, published earlier this year, of a black hole's "shadow." Because they exert so much gravitational force that even nearby light falls into them, black holes are very black. Compared with a black hole, any black clothing you have is actually navy blue.
Yet black holes are also thought to produce some of the universe's brightest known lights. These include blazars, the extremely hot jets of matter produced by the gases orbiting supermassive black holes, and gamma-ray bursts, the explosions of high-frequency radiation thought to occur when a black hole swallows a binary neutron star.
