Protons, the little positively-charged nuggets inside of atoms, are fractions of a quadrillionth of a meter smaller than anyone thought, according to new research.
In work they hope solves the contentious "proton radius puzzle" that has been roiling some corners of physics in the last decade, a team of scientists has addressed the question of the proton's radius in a new way.
They discovered that it is 0.831 femtometers across, which is about 4 percent smaller than the best previous measurement using electrons from accelerators.
A single femtometer is 0.000000000000039370 inches imperial, if that helps, or think of it as a millionth of a billionth of a meter. And the new radius is just 80 percent of that.
But this is a big — and very small — deal for physicists, because this measure of the proton's size will affect any precise calculation of energy levels in an atom, says Haiyan Gao, a professor of physics at Duke University.