The intense energy and winds from gigantic black holes can block the birth of stars as scientists have long suspected, a new analysis of distant galaxies reveals. Most galaxies, including our own Milky Way, are thought to have supermassive black holes at their hearts. Some of these monster black holes are relatively calm, but others, known as “active galactic nuclei,” or AGN, can spew out more radiation than our entire galaxy does, and from a patch of space no larger than our solar system. Scientists had long thought all this energy from active galactic nuclei quenched the formation of stars around them.