Magnetic lines of force
I’ve been thinking that there must be a way to focus magnetic fields to very precise shapes. As I drove to work this week, I imagined my car driving through such a field in a way that my car’s speakers vibrated from the field’s effects, creating sound as the car moved through it. I think it would be a neat trick to get sound from a car’s speakers independent of whether or not they’re connected to anything!
For a while I’ve been thinking that perhaps magnetic fields could be used as antennas. Rather than have a big, metal dish to collect signals toward a focal point, a magnetic field could be generated that would invisibly reflect radio signals toward a focal point. By strengthening or weakening the field, the virtual dish could be expanded or contracted as needed, raising or lowering the gain.
Magnetic fields are circular in nature and the challenge would be how to create a parabolic shape with a field. I also have no idea if a magnetic field can even be made to reflect radio signals. It’s an interesting idea, nonetheless.
Update 25 March: I am reminded that a device exists that can beam sound to a remote location, only for this one the receiver isn’t just a speaker, it’s a human brain! Behold MEDUSA, which makes use of the microwave auditory effect.