The existence of particles like electrons, protons, and quarks is supported by a wealth of experimental evidence and theoretical frameworks. While we cannot "see" these particles in the traditional sense, their existence and properties are inferred through indirect observations and experiments based on the predictions of various scientific theories.
Here are a few lines of evidence for the existence of these particles:
Scattering experiments: High-energy particle accelerators allow us to collide particles together at extremely high speeds. By studying the scattering patterns and energy distributions of the colliding particles, we can infer the presence and behavior of subatomic particles. Experiments such as electron-proton scattering have provided evidence for the existence of both electrons and protons.
Particle detectors: Sophisticated instruments and detectors are used to measure the interactions and effects produced by particles. These detectors can indirectly detect particles through their interactions with matter, such as ionization or electromagnetic radiation. Various types of detectors, including bubble chambers, cloud chambers, and particle accelerators, have provided evidence for the existence and properties of subatomic particles.
Particle interactions: The behavior and interactions of particles are described by theoretical frameworks such as quantum field theory. These theories provide a comprehensive mathematical description of particle interactions and have been tremendously successful in predicting and explaining experimental observations. The Standard Model of particle physics, in particular, has been highly successful in describing the behavior of particles and their interactions, including those of electrons, protons, and quarks.
Indirect effects: The presence and properties of particles can be inferred from their indirect effects on other physical phenomena. For example, the electromagnetic interactions between electrons and protons give rise to the structure of atoms and the behavior of electromagnetic radiation. The behavior of these particles in various experimental setups and the consistency of their effects in different contexts provide strong evidence for their existence.
It's important to note that the scientific process involves constructing and refining models based on observations and experimental evidence. The existence of particles like electrons, protons, and quarks is supported by a vast array of empirical data and theoretical consistency, making them fundamental components of our understanding of the physical world.