Nonconformists could take a page from the proton’s playbook: The subatomic particle is once again resisting scientists’ attempts to size it up.
Everyone agrees the proton is tiny: Its radius is less than a femtometer, or a trillionth of a millimeter. But scientists still don’t agree on exactly how small it is. A new measurement supports the case for a smaller proton, physicist Lothar Maisenbacher and colleagues report in the Oct. 6 Science. But “in some sense, it deepens the puzzle,” says Maisenbacher, of the Max Planck Institute of Quantum Optics in Garching, Germany.