wave-particle duality

(noun)

A postulation that all particles exhibit both wave and particle properties. It is a central concept of quantum mechanics.

Related Terms

Examples of wave-particle duality in the following topics:

  • Particle-Wave Duality

    • Wave–particle duality postulates that all physical entities exhibit both wave and particle properties.
    • Wave–particle duality postulates that all physical entities exhibit both wave and particle properties.
    • As a central concept of quantum mechanics, this duality addresses the inability of classical concepts like "particle" and "wave" to fully describe the behavior of (usually) microscopic objects.
    • Why then is it that physicists believe in wave-particle duality?
    • Because of its counter-intuitive aspect, the meaning of the particle-wave duality is still a point of debate in quantum physics.

  • de Broglie and the Wave Nature of Matter

    • The concept of "matter waves" or "de Broglie waves" reflects the wave-particle duality of matter.
    • In quantum mechanics, the concept of matter waves (or de Broglie waves) reflects the wave-particle duality of matter.
    • The de Broglie relations show that the wavelength is inversely proportional to the momentum of a particle, and is also called de Broglie wavelength.
    • Therefore, the presence of any diffraction effects by matter demonstrated the wave-like nature of matter.
    • Just as the photoelectric effect demonstrated the particle nature of light, the Davisson–Germer experiment showed the wave-nature of matter, thus completing the theory of wave-particle duality.

  • Energy and Momentum

    • Electromagnetic waves have energy and momentum that are both associated with their wavelength and frequency.
    • In other words, there were only certain energies an electromagnetic wave could have.
    • Energy of a wave is therefore "quantized. "
    • However, Einstein proved that light can act as particles in some circumstances, and that a wave-particle duality exists.
    • Relate energy of an electromagnetic wave with the frequency and wavelength

  • The Wave Function

    • A wave function is a probability amplitude in quantum mechanics that describes the quantum state of a particle and how it behaves.
    • In quantum mechanics, a wave function is a probability amplitude describing the quantum state of a particle and how it behaves.
    • For a single particle, it is a function of space and time.
    • This explains the name "wave function" and gives rise to wave-particle duality.
    • Relate the wave function with the probability density of finding a particle, commenting on the constraints the wave function must satisfy for this to make sense

  • Diffraction Revisited

    • De Broglie's hypothesis was that particles should show wave-like properties such as diffraction or interference.
    • The de Broglie hypothesis, formulated in 1924, predicts that particles should also behave as waves.
    • From the work by Planck (black body radiation) and Einstein (photoelectric effect), physicists understood that electromagnetic waves sometimes behaved like particles.
    • De Broglie's hypothesis is complementary to this idea: particles should also show wave-like properties such as diffraction or interference.
    • Thanks to the wave-particle duality, matter wave diffraction can also be used for this purpose.

  • The Photoelectric Effect

    • Study of the photoelectric effect led to important steps in understanding the quantum nature of light and electrons and influenced the formation of the concept of wave-particle duality.
    • At the time, light was accepted as a wave phenomenon.
    • Is light then composed of particles or waves?
    • Young's experiment suggested that it was a wave, but the photoelectric effect indicated that it should be made of particles.
    • This question would be resolved by de Broglie: light, and all matter, have both wave-like and particle-like properties.

  • Quantum-Mechanical View of Atoms

    • Bohr's model successfully explained spectroscopic data of hydrogen very well, but it adopted a semiclassical approach where electron was still considered a (classical) particle.
    • Adopting Louis de Broglie's proposal of wave-particle duality, Erwin Schrödinger, in 1926, developed a mathematical model of the atom that described the electrons as three-dimensional waveforms rather than point particles.
    • A consequence of using waveforms to describe particles is that it is mathematically impossible to obtain precise values for both the position and momentum of a particle at the same time; this became known as the uncertainty principle, formulated by Werner Heisenberg in 1926.
    • Quantum electrodynamics (QED), a relativistic quantum field theory describing the interaction of electrically charged particles, has successfully predicted minuscule corrections in energy levels.

  • Young's Double Slit Experiment

    • The double-slit experiment, also called Young's experiment, shows that matter and energy can display both wave and particle characteristics.
    • The double-slit experiment, also called Young's experiment, shows that matter and energy can display both wave and particle characteristics.
    • The light that appears on the wall behind the slits is scattered and absorbed by the wall, which is a characteristic of a particle.
    • This amplifies the resultant wave.
    • The amplitudes of waves add together.

  • Longitudinal Waves

    • An example of a longitudinal wave is a sound wave.
    • A sound wave contains pulses, which are the products of compressing the air (or other media) particles.
    • Some longitudinal waves are also called compressional waves or compression waves.
    • The difference is that each particle which makes up the medium through which a longitudinal wave propagates oscillates along the axis of propagation.
    • When people make a sound, whether it is through speaking or hitting something, they are compressing the air particles to some significant amount.

  • Water Waves

    • As a result, the particles composing the wave move in clockwise circular motion, as seen in .
    • In the case of monochromatic linear plane waves in deep water, particles near the surface move in circular paths, creating a combination of longitudinal (back and forth) and transverse (up and down) wave motions.
    • When waves propagate in shallow water (where the depth is less than half the wavelength), the particle trajectories are compressed into ellipses.
    • As the wave amplitude (height) increases, the particle paths no longer form closed orbits; rather, after the passage of each crest, particles are displaced slightly from their previous positions, a phenomenon known as Stokes drift.
    • The motion water waves causes particles to follow clockwise circular motion.