"The Wave-Particle Duality theory states that waves can exhibit particle-like properties while particles can exhibit wave-like properties.
the
double-slit experiment demonstrates that light and matter can exhibit behavior of both classical
particles and classical
waves. This type of experiment was first performed by
Thomas Young in 1801, as a demonstration of the wave behavior of visible light.
[1] In 1927,
Davisson and Germer and, independently,
George Paget Thomson and his research student Alexander Reid
[2] demonstrated that electrons show the same behavior, which was later extended to atoms and molecules.
[3][4][5] Thomas Young's experiment with light was part of
classical physics long before the development of quantum mechanics and the concept of
wave–particle duality. He believed it demonstrated that the
Christiaan Huygens' wave theory of light was correct, and his experiment is sometimes referred to as
Young's experiment[6] or Young's slits.
[7]

Photons or matter (like electrons) produce an interference pattern when two slits are used

Light from a green laser passing through two slits 0.4 mm wide and 0.1 mm apart
The experiment belongs to a general class of "double path" experiments, in which a wave is split into two separate waves (the wave is typically made of many photons and better referred to as a wave front, not to be confused with the wave properties of the individual photon) that later combine into a single wave. Changes in the path-lengths of both waves result in a
phase shift, creating an
interference pattern. Another version is the
Mach–Zehnder interferometer, which splits the beam with a
beam splitter.
Other atomic-scale entities, such as
electrons, are found to exhibit the same behavior when fired towards a double slit.
[9] Additionally, the detection of individual discrete impacts is observed to be inherently probabilistic, which is inexplicable using
classical mechanics.
[9]
The experiment can be done with entities much larger than electrons and photons, although it becomes more difficult as size increases. The largest entities for which the double-slit experiment has been performed were
molecules that each comprised 2000 atoms (whose total mass was 25,000
atomic mass units).
[19]"the
double-slit experiment demonstrates that light and matter can exhibit behavior of both classical
particles and classical
waves.In double slit experiment a wave is split into two separate wave, if matter exhibit behavior of waves, it means that not only light particles but matter particles like electrons and atoms , molecules can be split into two waves. If wave is split into 2 waves: does it mean after double split experiment particles multiply( there are more particles after double split experiment ), for example, there were 2 electrons, after experiment there are 4 electrons. If particles can multiply after double slit experiment, can people multiply spaceships through double split experiment? For example there was 1 spaceship, after double split experiment there are 2 spaceships.