号称宇宙的无人区，方圆五千光年没有一个星系，空洞究竟是什么2

The passage discusses the mysterious cosmic voids, with a focus on their low density, vast sizes, connection to dark energy, and the intriguing discovery of a billion-light-year-wide hole in the Orion constellation. Researchers explore theories about the formation and possible causes, such as gravitational effects and the influence of dark matter.