Wave-particle duality is a fundamental concept in quantum theory that describes the dual nature of elementary particles, such as electrons and photons. According to quantum theory, particles can exhibit both wave-like and particle-like properties, depending on how they are observed or measured.
In the context of wave-particle duality, particles can be described by a mathematical function called a wavefunction. The wavefunction describes the probability distribution of the particle's position or other observable properties. When a particle is not measured or observed, its wavefunction spreads out and behaves like a wave, exhibiting interference and diffraction phenomena.
One famous experiment that demonstrates wave-particle duality is the double-slit experiment. In this experiment, particles, such as electrons or photons, are fired towards a barrier with two parallel slits. When the particles pass through the slits, they create an interference pattern on a screen behind the barrier, indicating wave-like behavior. However, when individual particles are observed or measured, they behave as discrete particles, hitting the screen at specific points, akin to particle-like behavior.
This duality suggests that particles can exist in a superposition of states, where they are simultaneously in multiple states or locations until a measurement is made, which collapses the wavefunction into a specific state or position. The wave-particle duality is a fundamental aspect of quantum theory and has been experimentally confirmed through numerous experiments and observations.