When a child sprinkles iron filings onto a sheet of paper laid over a bar magnet, the tiny slivers stand up and align along invisible curves because each filing briefly becomes its own magnet — the same field-line pattern Michael Faraday sketched in 1831 to argue that empty space itself could carry

The iron filings that arrange themselves into curves over a bar magnet are drawing the same field lines Michael Faraday sketched in the 1830s — the picture that eventually convinced physics that empty space itself could carry force. The post When a child spri…