A magnetic field is like a shadow cast by an object: it changes with the shape of the source. But if you put a lens in the path of light, you can alter the shadow. Here, the authors devised a 'lens' for magnetic fields — an assembly of ordinary materials with different magnetic permeabilities (their ability to let the field through).

In the experiment, they took the field from a simple magnet and reshaped it into a specific form within an empty zone. It's like pouring water from a pitcher into a glass with an invisible hand — without a single coil or current.

This approach promises cheap and flexible magnetic shields, precise field delivery in medicine (e.g., for manipulating microparticles), and improved imaging in tomography.