When light hits a material, it knocks electrons out of it. By looking at where these electrons fly, you can learn how they lived inside: with what energy and in which direction. But if you switch on a magnet nearby, the electron paths curve. The picture blurs, like a reflection in a funhouse mirror.

Physicists found a way out. Instead of removing the magnet, they calculated exactly how it bends the paths. To do this, they simulated the electrons' flight on a computer, then built an inverse rule: if you know where an electron landed, you can work out where it came from. It is like a restorer who reconstructs a person's true features from a distorted reflection.

They tested the method on a material that conducts current only on its surface. Even with the magnet on, the picture became almost as sharp as without it. Now any scientist with a similar instrument can apply this approach and see how a magnetic field affects electrons in different materials.