Final answer:
New discoveries such as positrons, mesons, and neutrinos were originally referred to as 'elementary particles.' As the number of these particles grew, the term 'particle zoo' became more common, leading to the simplification efforts that introduced concepts like quarks.
Step-by-step explanation:
New discoveries of particles such as positrons, mesons, neutrinos, and others were originally referred to as elementary particles.
In the context of the history of particle physics, the prediction and discovery of new particles has led to significant developments. After the initial term 'elementary particles' became less reflective of the diversity and complexity of these particles, the term 'particle zoo' became popular due to the vast number of particles that were discovered. However, through observation of patterns within this particle zoo, physicists were able to propose simplifying concepts like quarks, which helped make sense of the multitude of subatomic particles and their interactions.
Key figures in the advancement of particle physics include P.A.M. Dirac, who predicted the positron, and Carl Anderson, who later discovered it. Yukawa predicted pions which play a role in the strong nuclear force, and upon their discovery, they confirmed the theoretical predictions. Later, with the advent of powerful particle accelerators, many more particles were created and discovered, eventually leading to a deeper understanding of particle physics and the forces that govern them.