A 22-year-old student at Stockholm University, Elin Oxenhielm, may have cracked part of one of mathematics' greatest unsolved problems. Called Hilbert's problem 16, it has confounded workers for over a century. But in just a few hours of inspiration, Oxenhielm saw the light. Her solution is to be published in a maths journal. Her research into so-called planar polynomial vector fields may have practical applications for computer simulations in science and economics.