According to our current understanding in modern physics, elementary particles are described as both particles and excitations of underlying quantum fields. This perspective is based on quantum field theory, which is the framework used to describe the behavior of particles and their interactions.
In quantum field theory, particles are treated as excitations of their corresponding fields. Each type of elementary particle, such as electrons, quarks, or photons, is associated with a specific quantum field. These fields pervade all of space and time, and particles are considered localized disturbances or excitations of these fields.
Particles can be thought of as quantized vibrations or "quanta" of their respective fields. Just as waves can be described as the collective behavior of many particles, particles can be understood as the localized manifestations of underlying wave-like fields.
This viewpoint is consistent with the principles of quantum mechanics, which introduce wave-particle duality. It means that particles, including elementary ones, exhibit both particle-like and wave-like properties, depending on how they are observed or interact.
When we observe or measure particles, they often behave like discrete entities with specific properties such as mass, charge, and spin, resembling classical particles. However, in other experiments or situations, particles exhibit interference, diffraction, and other wave-like phenomena.
In summary, elementary particles are described as both particles and excitations of wave-like fields. This dual nature is a fundamental aspect of quantum field theory and reflects the behavior observed in experiments and supported by theoretical frameworks.