Physicists Are Closer to Knowing the Size of a Proton … Sort of


How big is a proton? That might sound like a pretty simple question, but it turned out to have the potential to wreck a lot of modern physics. That's because different methods of measuring the proton's charge radius produced results that disagreed--and not just by a little bit. The answers were four standard deviations apart. But now, a new and improved measurement brings them into much closer alignment--though not quite close enough that we can consider the issue resolved. This story originally appeared on Ars Technica, a trusted source for technology news, tech policy analysis, reviews, and more.