How do the universe's first black holes seed themselves in isolation?

The earliest supermassive black holes may have grown from unusually massive, metal-free stars that only form in completely isolated environments. Using simulations, researchers show that ionizing radiation from these stars carves out expanding bubbles around themselves, naturally setting their spacing to roughly 1.3 million light-years apart. This self-regulating feedback predicts the observed abundance of early black holes and suggests LISA can detect their collisions.