This is not just computer graphics. It’s the magnetic field of a real bar magnet, imaged using a neutron beam. Neutrons have no electric charge, which enables them to fly straight through a magnetic field and to zip through thick solids unaffected (SN: 3/18/08) But neutrons possess a magnetic moment. Like tiny bar magnets, they will tend to align their magnetic moment with that of a magnetic field. Using this fact, Nikolay Kardjilov of the Hahn–Meitner Institute in Berlin and his collaborators have scanned magnetic fields by shooting neutrons through the fields from different angles and by reconstructing a 3-D image, the way a CAT scan is assembled from different X-ray shots. The researchers have also visualized the magnetic fields inside a superconductor, as they describe in the May Nature Physics.