For her 7th birthday, my niece received a very special gift — a compound light microscope with a set of slides. As soon as we got it out of the package, she became a diligent young investigator, studying the leg of a fly, dog cardiac muscle and onion epidermal cells. But it wasn’t the prepared slides that captivated her most. She wanted to investigate more familiar things. We plucked hairs from our heads to see what they looked like, and collected dirt from various spots across the yard to compare and contrast. Sitting at the dining room table, she drew big circles on notebook paper and sketched her newfound views. The world she thought she knew was suddenly unexpected.
At one time or another, a similar feeling must have motivated researchers studying the proton. Here’s a basic constituent of matter that, as physics writer Emily Conover writes, makes up stars, planets and people (also, peonies, blue jeans and gelato — a few of my favorite familiar things). The proton has been observed, albeit indirectly, for about a century. Its place at the center of the atom is etched into our minds. Heck, we even control it — smashing protons together at near light-speed in giant particle colliders.