The proton - smaller than thought
Big problems sometimes come in small packages. The problem with which physicists must now concern themselves measures a mere 0.0350 millionth of a millionth of a millimetre. This is precisely the difference between the new, smaller, dimension of the proton, the nucleus of the hydrogen atom, and the value which has been assumed so far. Instead of 0.8768 femtometres it measures only 0.8418 femtometres. At the Paul Scherrer Institute in Switzerland, an international team of researchers including physicists from the Max Planck Institute of Quantum Optics has now measured this in experiments which are ten times more accurate than all previous ones. They thus present physics with some tough problems: at least one fundamental constant now changes. And physicists have also to check the calculations of quantum electrodynamics. This theory is assumed to be very well proven, but its predictions do not agree with these latest measurements...