Thanks to [Andrew Klein] and this video on shop-built magnetic switches ... two thick plywood discs with magnets set into the edges. These magnets alternate in polarity around the discs, and ...

The direction of the magnetic field switches to the opposite direction from one layer to the next. This is an antiferromagnetic structure. Above 132 Kelvin, the material isn't magnetized—the ...

As the time line at right shows, hundreds of times in our planet's history the polarity of the magnetic shield ensheathing the globe has gone from "normal," our current orientation to the north ...