384 Hz

Forty-two minutes before sunrise on the vernal equinox, Dujiangyan Fish Mouth. An engineer squatted by the Minjiang River, put down his self-soldered hydrophone, and recorded a voiceprint that lasted seventeen seconds. Frequency: 384.0 Hz. Error: ±0.01 Hz. No known sound source in nature can produce this level of accuracy. He traced it back. There is a record of "Dragon Yin" in the local chronicles of the Tang Dynasty. In 1974, a stone statue of Li Bing was unearthed under the Anlan Cable Bridge. There is an underwater photo in the 2023 dredging report. There is a set of regularly arranged wave-shaped notches carved three meters from the bottom of the fish's mouth. A transparent fragment was taken out of the core from the pile, with a micro-grating structure on the surface, which is consistent with the characteristics of laser processing. The correlation between the water sound of South Bridge and the quantum random number sequence reaches 99.9999%. Then he discovered: Dujiangyan may not be a water conservancy project. It is a protocol interface that has been in continuous operation for more than two thousand years. It connects the present world to a bottom layer that cannot be verified. All clues have real-world counterparts. You can check for yourself: No. 99 Shuangyuan Street Water Conservation Building, Zipingpu Hydrological Station, and the soy milk steamed buns on Ruilian Street. But the explanation—that explanation cannot be independently and repeatedly verified. This is not a story about "finding the answers." This is a story about "confirmation of unanswerability". Frequency can be recorded. But the source of the sound has never been identified.