The proton is a fundamental building block of matter. This is what makes it all the more disturbing is that there is some disagreement as to how big this subatomic particle is. A consensus is now looming but not all particle physicists are happy about it.
Every once in a while, an experiment delivers results which, at first glance, seem to contradict the standard model of particle physics. The excitement is particularly great since researchers are desperately searching for a better model but, with frustrating frequency, the discrepancy falls apart upon closer scrutiny. It is possible that history is now be repeating itself again. At the Jefferson Laboratory in the US, researchers have scattered electrons in amongst protons in order to measure the radius of this subatomic particle. The result brings the solution to a puzzle that particle physicists have been struggling to solve for years that little bit closer.