The wave-particle duality is a fundamental concept in quantum mechanics that states that particles can exhibit both wave-like and particle-like properties. However, the wave properties of particles are typically observed at the quantum level, specifically when studying very small particles such as electrons, protons, or photons. There are a few reasons for this:
Wave nature becomes more apparent at smaller scales: The wavelength associated with a particle is inversely proportional to its momentum. For macroscopic objects, such as everyday objects, the wavelength associated with their motion is incredibly tiny and undetectable. However, at the quantum level, particles have such small masses and high velocities that their associated wavelengths become significant and observable.
Quantum uncertainty and measurement disturbance: The act of measuring a particle's properties can disturb its behavior. This is known as the Heisenberg uncertainty principle. The more precisely we try to measure a particle's position, the less precisely we can determine its momentum, and vice versa. This principle limits our ability to simultaneously know the exact position and momentum of a particle, which is intimately connected to its wave-like behavior.
Interference and diffraction effects: When waves interact, they can exhibit interference and diffraction patterns. These phenomena occur when waves combine or spread out when passing through slits or obstacles. At the quantum level, particles can also exhibit interference and diffraction patterns, suggesting their wave-like nature. These effects become more noticeable when dealing with small particles, where the wavelength associated with their motion is comparable to the size of the obstacles they encounter.
Overall, the wave properties of particles are more pronounced and observable at the quantum level, where the inherent uncertainty and small scales play significant roles.