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.