Lurking at the heart of every atom is the proton, a tiny particle from which chemical elements are created, first in the heat of the Big Bang and then in the nuclear reactors of stars. The number of protons in the atom determines whether it is hydrogen, carbon, oxygen, or uranium. They make up over 86 percent of the visible matter in the universe by mass and are the basis of our existence. But we still don’t really understand them.
Just over a century ago, Ernest Rutherford demonstrated that the proton is one of the basic building blocks of all atomic nuclei. But despite our best efforts so far, much about this ubiquitous particle remains a mystery.
Do protons live forever, how big are they, and what are they actually made of are just some of the questions that physicists continue to grapple with. Finding answers doesn’t just change the way we think about the particles themselves. It can change our understanding of the universe and the fundamental laws that govern it. Here are five of the biggest unanswered questions about protons.
1. What are protons made of?
The simple and oft-repeated story is that the proton is made up of three quarks (two up quarks and one down quark) held together by the vise-like force of the powerful nuclear forces that hold the nuclei together. about it. But when physicists began to consider higher resolutions, these he-three “valence” quarks in the proton were in a quantum-mechanical churning sea of other particles that existed and vanished. I discovered something.
Most of the time, …
