Smallest Observed Object in the Universe

Over the last century science has made both great strides into understanding the vastness ofspaceand its microscopic building blocks. When it comes to figuring what the smallest observable particle in the universe is, however, we run up against a bit of a wall. At one point we thought they it was the atom. Then scientists discovered the proton, neutron, and electron. It didnt stop there though. Today we know (by smashing particles together in places like the Large Hadron Collider) that these can be further broken down into even more particles like quarks, leptons, and even antimatter. The issue with trying to figure out which is smaller is that on a quantum level size becomes a bit irrelevant as the rules of physics you are used to living by begin to break down (some particles have no mass, some even have negative mass) Unfortunately, trying to answer this question is something like dividing by zero