The concept of particles being "wave-packets" arises from quantum mechanics, which describes the behavior of particles at the microscopic scale. In quantum mechanics, particles are described by wave functions, which are mathematical functions that can exhibit wave-like properties.
A wave-packet represents a localized and confined disturbance in the wave function that describes a particle. It is a mathematical construct that combines the ideas of waves and particles. A wave-packet represents the superposition or combination of multiple waves with different frequencies and wavelengths.
In the quantum mechanical framework, particles can exhibit wave-like properties such as interference and diffraction. However, it's important to note that when we refer to particles as wave-packets, we are not implying that they are classical waves in the sense of oscillating in physical space like water waves or sound waves. Rather, the wave-packet describes the probabilistic behavior of the particle's wave function, which contains information about the probability distribution of the particle's position and momentum.
The wave-packet concept allows us to understand that particles can exhibit wave-like behavior while also being localized in space. It describes the uncertainty and dual nature of particles in quantum mechanics, where they can behave both as particles and waves depending on the experimental context.