Wave-particle duality represents a fundamental postulate in quantum mechanics asserting that every elementary particle exhibits both wave-like and particle-like properties depending on the experimental context. This principle is mathematically formalized through the de Broglie relation, which connects momentum to wavelength via Planck's constant, fundamentally altering classical definitions of mass-energy localization within the field of theoretical physics. The concept serves as a core pillar distinguishing quantum behavior from classical mechanics and establishes the probabilistic nature inherent in wave function descriptions rather than deterministic trajectories.
Contrasts everyday particle behavior (a dropped ball follows one trajectory) with wave behavior (sound spreads and interferes), then sets up why quantum objects like photons and electrons show both k…