The Janitor Who Solved the Equation

In 2016, a custodian named Srinivasa at a research facility in Bangalore, India, noticed a whiteboard equation that professors had struggled with for weeks. He stayed after his shift, picked up a marker, and — drawing on self-taught mathematics he'd learned from library books — sketched out an elegant solution. The researchers arrived the next morning, stunned. They had consulted PhDs from three universities.…