The current Standard Model of particle physics is indeed a tightly constructed mechanism with only a handful of ingredients. Yet instead of being unique, the universe seems to be one of an infinitude of possible worlds. We have no clue why this particular combination of particles and forces underlies nature’s structure. Why are there six “flavors” of quarks, three “generations” of neutrinos, and one Higgs particle? Furthermore, the Standard Model comes with 19 constants of nature — numbers like the mass and charge of the electron — that have to be measured in experiments. The values of these “free parameters” seem to be without any deeper meaning. On the one hand, particle physics is a wonder of elegance; on the other hand, it is a just-so story.
Read more from Robbert Dijkgraaf, Institute Director and Leon Levy Professor, as he explores the complex search for a single description of reality and how modern physicists embrace the vast space of possibilities at Quanta.