I’ve explained numbers of times that if the Hum is caused in part by VLF transmissions, then simple shielding or Faraday cages will not block it. VLF radio waves can deeply penetrate many materials, including up to a full inch of solid aluminum. After examining a list of materials and their properties, I discovered that mild steel (as opposed to other types) has an ideal combination of properties for creating a Hum shield. The good news is that a thin 1.2 mm layer of mild steel should do the job. There is a catch, however. VLF waves are very good a finding their way through cracks and openings in any container, and therefore the shielding must not only be total, but the welding has to be excellent. This raises concerns about how to get fresh air, light, and other necessities of life into the box/container so that volunteer participants can be comfortable.
Solving the above technical issue is a first step in moving toward the first formal and controlled experiments on the Hum.