Xuanchen Belt

Deep in the mountains of Guizhou, the world's largest radio telescope captured a periodic signal amidst the background noise that should not have existed. Its frequency is exactly the same as the "Anomaly No. 31" Written down on the paper tape by a forgotten old scientist fifty-five years ago. It was a snowy night in 1971. Observer Gu Yuanzhou heard a gentle "knocking" in the universe at the Yunling Observation Station in the mountainous area of ​​northern Guizhou. His superiors cited "equipment failure" to suppress the conclusion, and he only wrote one line in a torn-up copy of "Selected Poems of the Tang Dynasty": "Someone has to remember it." This sentence has been hanging for fifty-five years. In 2026, young scientist Shen Li encountered the same frequency again at FAST. He and brain-computer interface expert Su Yao discovered that this signal is not natural noise. It is encoded with the brain electrical rhythm of human memory and forgetting - like some very ancient civilization that deliberately chose a language that "will be remembered" and said the same sentence repeatedly in the dark. A "lighthouse". A certain civilization hundreds of millions of years ago sealed fire into the rhythm of millisecond pulsars, just to prove: you are not alone. But a dark river in the Milky Way called the "Xuanchen Belt" is slowly turning towards the solar system. The axion cloud it carries will quietly erode the memory of all carbon-based life. Forgetting is another kind of destruction of civilization by the universe. From the fog and snow in the southwestern mountains to the space station in low-Earth orbit, from the low-frequency array on the back of the moon to the young generation exiled on alien planets, the legacy of the Qiming clan, the whispers of the amnesiacs, the allies of the star patrollers, and the games of the Fusi clan have been intertwined into a web of civilization for hundreds of years.