Waveparticle

Wave-particle duality is a fundamental concept in quantum mechanics describing how quantum objects exhibit both wave-like and particle-like properties depending on the experimental context. In some experiments they produce interference and diffraction patterns typical of waves; in others they arrive as localized quanta, behaving like particles.

The concept emerged in the early 20th century with Louis de Broglie’s hypothesis that matter has a wavelength λ = h/p. This idea was supported by electron diffraction experiments and extended to other particles, while light showed wave-like behavior in interference and diffraction and particle-like aspects in the photoelectric effect. The dual nature became a cornerstone of quantum theory, guiding how physicists understand microscopic systems.

The theoretical framework centers on the wavefunction, whose evolution is described by the Schrödinger equation. The de Broglie relation links momentum to wavelength, and the Born rule assigns probabilities to measurement outcomes from the wavefunction’s amplitude. Measurements reveal particle-like detections, while the probabilistic wave aspects govern interference and diffraction phenomena.

Interpretations of wave-particle duality vary. Bohr’s complementarity posits that wave and particle descriptions are complementary, not simultaneously observable, and that the experimental setup determines which aspect appears. Decoherence helps explain the emergence of classical behavior in macroscopic systems. Wave-particle duality underpins many applications, including electron microscopy, quantum optics, and the design of semiconductors, reflecting the unified description of nature offered by quantum mechanics.