Sorting good sperm from bad may have just gotten easier. Scientists have come up with a new way to test the viability of human sperm by using a technique called magnetic resonance spectroscopy (MRS). Other testing methods either can’t provide much detailed information or damage the cells in the process. MRS, however, lets experts study the molecules inside cells while in action, to determine the properties of healthy swimmers. The technique could lead to better male infertility tests.