Things have a wave nature and a particle nature, just as photons do.
The pivotal question was then: how to unify Maxwell's wave theory of light with its experimentally observed particle nature?
More generally, the theory states that everything has both a particle nature and a wave nature, and various experiments can be done to bring out one or the other.
A 15,000-ton detector under construction in Minnesota will use an even more powerful neutrino beam from Fermilab's accelerator complex to pin down the particle nature of neutrinos.
This may make the top quark the heaviest particle nature has ever created.
The term also applies to photon counting in optical devices, where shot noise is associated with the particle nature of light.
In 1923 Louis de Broglie addressed the question of whether all particles can have both a wave and a particle nature similar to the photon.
It wasn't until the 1930s that the particle nature of light really began to be widely accepted in physics.
The double-slit experiment is meant to observe phenomena that indicate whether light has a particle nature or a wave nature.
Exceptions occur when the particle nature of light is important or for very strong electric fields.