At one time physicists thought that the atom was the smallest unit of matter. Then, in the 19th century protons, electrons, and neutrons were discovered that make up atoms, and have positive, negative, or no electrical charge respectively. Naturally, this inspired much research on the nature of these particles. In particular, the questions of whether these constituted all of the subatomic particles and whether these were indecomposable into even smaller particles. Over time, more subatomic particles were discovered, and labeled elementary if they were not composed of smaller particles. Muons, pions, photons, bosons were one many discoveries, and determining their properties required further research.
It turned out that an abstract area of mathematics, namely Group Theory, was useful in organizing the collective information. As a mathematician, I was fascinated by the fact that particle physicists believed the picture would be more elegant if other particles existed with specific properties. Given these properties, the physicists were able to design experiments to detect the conjectured particles. They succeeded. It was as if a biologist predicted the existence of an animal whose size, appetite, and habits were known, and then set a trap appropriately large with enticing food in an area conducive to its existence. I love that the physicists believed that the universe consists of mathematical beauty.
The newly discovered particles were called quarks, which came in six “flavors”: up, down, top, bottom, charm, and strange. Each of the six quarks has an antiquark. Originally, only three quarks were discovered. Further, it turns out that one can never isolate a quark. It always occurs with its antiquark partner.
When the Rubik’s cube became all the rage, I used Group Theory to concoct moves that could be used to restore a messed up cube. It turns out that one can never have a single twisted corner and all the other pieces in place, but you can have two twisted corners, one clockwise and the other counterclockwise like the quark and antiquark. What a fun coincidence! Well, not a total coincidence since Group Theory is the connection.
What’s most new—within the last decade— is the discovery at CERN of a subatomic particle made up of four quarks. The article calls the particle exotic, possibly because it’s the first made up of four quarks of the same flavor, namely charm, and of course their antiquarks.
What is interesting is that some posited particles such as the Higgs boson exist but have extremely short lives once isolated.
Physicists are amazing and also have an amazing sense of humor. Check out the faux and funny discovery of a new substance called administratium. It has one neutron, 125 assistant neutrons, 75 vice neutrons and 111 assistant vice neutrons.