November 24, 2020 | Scientists have figured out a way to create and cancel magnetic fields from afar.
The method involves running electric current through a special arrangement of wires to create a magnetic field that looks as if it came from another source. This illusion has real applications: Imagine a cancer drug that could be delivered directly to a tumor deep in the body by capsules made of magnetic nanoparticles. It's not possible to stick a magnet in the tumor to guide the nanoparticles on their journey, but if you could create a magnetic field from outside the body that centered right on that tumor, you could deliver the drug without an invasive procedure.
The strength of a magnetic field decreases with distance from the magnet, and a theorem proven in 1842, Earnshaw's Theorem, says that it's not possible to create a spot of maximum magnetic field strength in empty space.
"If you cannot have a magnetic field maxima in empty space, it means you cannot create the field of a magnetic source remotely, without placing an actual [magnetic] source at the target location," said Rosa Mach-Batlle, a physicist at the Istituto Italiano Di Tecnologia Center for Biomolecular Nanotechnologies in Italy who led the new research.
