None of them knew what, exactly, was causing these symptoms. But they all shared a singular grievance: a dull aural hum had crept into their lives, which growled or roared depending on the time of day, rattling their windows and rendering them unable to sleep. The hum, local law enforcement had learned, was emanating from a Bitcoin mining facility that had recently moved into the area—and was exceeding legal noise ordinances on a daily basis.