Readers may wish to skip to the video, below, if they’re too holidayed to want to read too many words. For the rest: a group of Aoyama Gakuin University researchers has demonstrated a magnetic-levitation disk that can be moved using lasers.
The trick is in the materials: when the laser heats one part of the disk, the magnetic properties change in a small area. The resulting differential in the force applied to the disk makes it move – as you can see here:
The graphite disk starts by being levitated over a magnet, with its height determined by the strength of the magnetic field and the diamagnetic properties of the disk.
The disk’s diamagnetism is a function of temperature (among other things). If it’s heated, the excitation of electrons weakens the diamagnetic properties. Heat the disk evenly, and it will fall closer to the magnet; but if you heat it locally, it will move in the direction of the beam.
The trick even works with sunlight, the researchers claim, with the disk able to reach a speed of 200 rpm. If the researchers could overcome the challenges of scaling this system up to a decent size, they say their system could even offer a new approach to converting light to electricity. In a more blue-sky scenario, they even imagine it being used for a transport system propelled by magnetism and light.
More immediately, the researchers plan trying their system out with a magnetic turbine blade, to see how much energy can be harvested from the phenomenon. ®