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.

  • The de Broglie Wavelength

    • At the end of the 19th century, light was thought to consist of waves of electromagnetic fields that propagated according to Maxwell's equations, while matter was thought to consist of localized particles.
    • Thus it became apparent that light has both wave-like and particle-like properties.
    • In his 1924 PhD thesis, de Broglie sought to expand this wave-particle duality to all material particles with linear momentum.
    • That same year, Max Born published his now-standard interpretation that the square of the amplitude of a matter wave gives the probability of finding a particle at a given place.
    • This interpretation was in contrast to de Broglie's own interpretation, in which the wave corresponds to the physical motion of a localized particle.

  • Properties of Waves and Light

    • In this section, we will focus on the wave-like properties of light.
    • While you will later learn about wave/particle duality (how light behaves as both a wave and a particle at the same time), here we shall discuss the wave nature of light and the experimental effects of this behavior.
    • Wave motion arises when a periodic disturbance of some kind is propagated through a medium.
    • If light consisted strictly of ordinary or classical particles, and these particles were fired in a straight line through a slit and allowed to strike a screen on the other side, we would expect to see a pattern corresponding to the size and shape of the slit.
    • If light were purely a particle, it would not exhibit the interference pattern shown here.

  • 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.