Galaxies could live longer if supermassive black holes act as their “hearts and lungs,” keeping them breathing and preventing them from growing too big. That’s the suggestion of a new study, which suggests that the universe would have aged much faster and today be filled with “zombie” galaxies containing dead or dying stars if it weren’t for the supermassive black holes that are thought to reside at the heart of all large galaxies. The astrophysicists behind the discoveries compare the jets of gas and radiation that supermassive black holes blow from their poles into their airways to breathing and lungs.