How big is a proton? We may finally have the answer to this puzzle

There’s a problem with protons, but we’re one step closer to solving it. We aren’t quite sure what the radius of a proton is and a new way of measuring has helped to fix the puzzle.

Until 2010, we were fairly sure about the size of the proton. We had measured it using hydrogen atoms, which are made of one proton and one electron. But in 2010, a measurement using muonic hydrogen – where the electron is replaced by another particle called…