According to quantum mechanics, all matter, including particles such as electrons and atoms, exhibits wave-particle duality. This means that particles can exhibit both wave-like and particle-like properties. The wave-like nature of particles is described by their associated de Broglie wavelength.
The de Broglie wavelength (λ) is given by the equation λ = h / p, where h is Planck's constant and p is the momentum of the particle. This equation indicates that the wavelength of a particle is inversely proportional to its momentum. Since momentum is related to the particle's velocity, the wavelength of a particle becomes significant when its velocity is comparable to the speed of light.
At absolute zero temperature (0 Kelvin or -273.15 degrees Celsius), particles in a substance have minimal thermal energy, and their velocity approaches zero. As a result, their momentum decreases, and their de Broglie wavelength increases significantly. This means that at very low temperatures, even macroscopic particles such as atoms and molecules can exhibit measurable wave-like properties.
While observing the wave nature of macroscopic objects is challenging due to their large mass and low velocities, experiments have demonstrated the wave behavior of larger particles, such as buckyballs (large carbon molecules) and even small clusters of atoms. These experiments support the concept of matter having a wavelength, even at temperatures close to absolute zero.