At Last, Physicists Understand Where Matter’s Mass Comes From

From macroscopic scales down to subatomic ones, the sizes of the fundamental particles play only a small role in determining the sizes of composite structures. For protons, the quarks barely play a role at all in determining its mass.MAGDALENA KOWALSKA / CERN / ISOLDE TEAM

In this Universe, there are very few fundamental properties that cannot be derived from something simpler. The rules governing biological systems are rooted in chemical interactions, bonds, and applied voltages. The rules of chemistry can be derived from more fundamental physical laws that govern all particles. And if you strip down the components of any physical system, you’ll eventually arrive at the simplest descriptions of reality we know of: the particles and interactions that make up all of our known reality. While all the particles that exist have their own specific, unique properties, there are only a few that define them, such as mass, electric charge, color charge, and weak hypercharge. Yet why the particles have the properties they do is not fully understood; the values of the fundamental constants behind the Universe cannot be derived from anything presently known.

The values of the fundamental constants, as they were known in 1998, and published in the Particle Data Group’s 1998 booklet.PDG, 1998, BASED ON E.R. COHEN AND B.N. TAYLOR, REV. MOD. PHYS. 59, 1121 (1987)

For thousands of years, humanity has searched for the smallest, most fundamental building blocks of nature. Since ancient times, we conjectured that there would be some smallest, uncuttable entities that composed everything in existence. The Greek word ἄτομος, where we get our word “atom” from, literally means indivisible, and yet atoms themselves can be broken up further: into protons, neutrons, and electrons. The electrons are truly uncuttable, but protons and neutrons can be broken up further: into quarks and gluons.

The quarks, antiquarks, and gluons of the standard model have a color charge, in addition to all the other properties like mass and electric charge. All of these particles, to the best we can tell, are truly point-like, and come in three generations. At higher energies, it is possible that still additional types of particles will exist.E. SIEGEL / BEYOND THE GALAXY