Having trouble figuring out how much you really weigh because the scale in the bathroom shows a slightly different result every time? Meanwhile, scientists at the ALICE experiment at CERN have managed to determine the mass of an alluring quark - an elementary particle that weighs about half a millionth of a billionth of a gram and is released for only a fraction of a second at the enormous temperatures created in particle collisions inside the Large Hadron Collider.