Zhengxiang Li

Two ocean liners sail at night without lights. One was built in a shipyard from steel plates, the other seems to have grown by itself from foam and waves. By ear they are almost indistinguishable, but an experienced hydroacoustician will catch the difference in the hum of the propellers and the contours of the hull.

Black holes come in lightweights, born from dying stars, and supermassive ones at galactic cores. The missing intermediate link had been hiding. Fast radio bursts, cosmic signals lasting milliseconds but carrying the energy of days of sunlight, helped crack the case. Think of these bursts as cries from the depths of the universe.

Eight bright spots on the radio sky. They are all the same quasar HS 0810+2554, whose light passed through a gravitational lens — a massive foreground galaxy.