The discovery of quarks was not made by directly "visualizing" them in the traditional sense. Quarks are elementary particles that are considered to be fundamental building blocks of matter. They are not directly observable because they are always confined within larger particles, such as protons and neutrons. Instead, their existence and properties were inferred through indirect experimental evidence and theoretical considerations.
The discovery of quarks can be attributed to a series of experiments in the mid-20th century. In the 1960s, deep inelastic scattering experiments were conducted, in which high-energy electrons were fired at protons and neutrons. These experiments revealed that the protons and neutrons had smaller constituents within them, which were later identified as quarks. The behavior of the scattered electrons and the analysis of the data provided information about the internal structure of nucleons (protons and neutrons) and indicated the presence of point-like particles.
The concept of quarks was proposed independently by Murray Gell-Mann and George Zweig in 1964 as a way to explain the patterns observed in particle interactions and the classification of various hadrons (particles composed of quarks). Quarks were postulated to have fractional electric charges and were considered to be the underlying particles responsible for the structure and properties of protons, neutrons, and other particles.
Further experimental investigations, such as deep inelastic scattering experiments and particle accelerator studies, provided additional evidence supporting the existence of quarks. These experiments involved studying the scattering and fragmentation of particles and analyzing the patterns of particle interactions. The results confirmed the presence of quarks and their properties, such as fractional electric charges and the concept of quark confinement.
In summary, the discovery of quarks was not based on direct visualization but rather on a combination of experimental observations and theoretical explanations that accounted for the behavior and properties of particles and the patterns observed in their interactions.