Anyone who studies wave optics will sooner or later encounter references to Jung's experience. In this case, we are really talking about an epoch-making discovery, which radically influenced the further development of science. But first things first.
Ray of light in the darkness of doubt
The light we see is what surrounds every person from birth. It is simple and complex at the same time. There is nothing surprising in the fact that attempts were constantly made to explain what light is and what its properties are. Serious debates flared up among adherents of various models, but no one could put an end to this issue. This happened until Jung's experiment was carried out, brilliantly confirming the wave theory of light.
It was previously believed that light is a stream of special particles - corpuscles. A little later, in full accordance with the discoveries of physics, photons replaced the corpuscles. A photon is a particle that has zero charge and mass, and also exists only at the speed of light. At the same time, Newton had an interesting experiment in observing the properties of light: he placed a glass plate and a concave lens between himself and the source. Moreover, he observed not a point source, but rings (subsequently named after him). Since Jungβs experiment was not yet set at that time, Newton could not explain what was observed from the point of view of the theory of light consisting of particles.
Double slit experiment
Finally, in 1803, T. Jung decided to finally confirm or refute the corpuscular hypothesis. He prepared and performed the simplest experiment, which forced scientists to take a fresh look at familiar things. Jung's experience showed that light is an electromagnetic wave with certain characteristics.
A sheet of opaque material was taken, two parallel slots were made in it with a width corresponding to the wavelength of the emitted "test" light. At a distance from the sheet was a screen that allows you to observe the "behavior" of light. A luminous flux from a point source was directed onto the sheet. Jung reasoned correctly: if the light is a stream of particles, then two parallel lines would be displayed on the screen. The maximum intensity of the luminescence would fall at the places where two rays fell, and between them there would be darkness (the sheet is opaque). But if the corpuscle theory were to be erroneous, then a light wave passing through the cracks would create secondary waves (the principle formulated in 1678 by H. Huygens). Since nothing hinders their distribution, theoretically, they would reach the middle of the screen between the projections of the slits, and their wave amplitude and phase coincided. Due to interference (superposition), this could lead to the greatest brightness of the light strip just between the projections of each slit, which would allow us to state that light is one of the manifestations of wave disturbances.
As is now known, the corpuscular hypothesis has fallen, and its wave point of view has taken its place. On the screen, bands with different intensities of luminescence were observed. The brightest is in the middle, then dim, etc. The decrease in luminosity is due to the antiphase of the secondary interfering waves.
However, in our time, after a series of refinement experiments, the theory was amended. In accordance with them, it is generally accepted that light has a dual nature, manifesting itself both as a wave and as a particle. The results of the experiments depend on their formulation. The latest quantum theory of the structure of the universe easily explains this: the observation results are obtained exactly as the experimenter wants to see them. Duality is inherent not only to light, but also to such a seemingly studied particle as an electron.