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Basic aspects of
quantum physics

The great physicist Dirac writes: "the Development of physics may occur in small steps, but at certain moments there is the introduction of something completely new, which breaks the scientific scheme and opens up new prospects."

Overcoming the old Newtonian physics
In 1803, atoms were considered as the main components of the subject.
In 1874, stony discovered the electron, and then Rutherford discovered the atomic nucleus, positively charged, surrounded by negatively charged electrons, like the sun in the middle of the planets of the solar system.
Subsequently, following Maxwell's electromagnetic theory, it was concluded that the atom should have collapsed, instead it remained stable. At the turn of the nineteenth and twentieth centuries, studies of the photoelectric effect called into question the completeness of classical mechanics, suggesting that electromagnetic radiation had a double behavior, undulating and corpuscular when interacting with matter.
Based on this "scientific contradiction" of the hydrogen atom, a theory was developed to explain the phenomena that occur at the atomic level, for which classical Newtonian mechanics completely inadequate. Thus was born quantum physics, which describes the behavior of matter, radiation and all their interactions, which should be considered as wave-like phenomena, as a wave dualism of particles.

Wave of duality
In the field of science, this was a real revolution, because classical or Newtonian physics considers light only as a wave, and the electron only as a particle. In order to describe this phenomenon of fundamental quantum physics, we can consider the experiment of two slits in which electron beams pass: if you open only one slit (for example, the left one), on the glass of the camera, you will get a projection of the slit. Opening only the right slit forms a mirror figure to the previous one. Therefore, light reacts perfectly to Newton's corpuscular theory. If both slits are opened at the same time, an interference pattern is created, i.e. in this case the light behaves like a mechanical wave: on the photographic film, we would have peaks or bellies overlaid in some places, in other deletions. This clearly proves the existence of the wave-
corpuscular dualism, both matter and electromagnetic radiation.

Principle of complementarity
Niels Bohr also introduced the principle of complementarity, according to which two aspects, corpuscular and wave, can not be observed simultaneously, because they exclude each other, i.e. type the experiment determines the subsequent behavior of the particles involved.
As long as the electron does not reach the goal, it is never at a certain point in space, but exists in the abstract and potential state described by the function a probability that propagates as a wave rather than following a specific trajectory.

The Schrodinger cat paradox
This is a very famous thought experiment in theoretical discussions in the interpretation of quantum mechanics. His scenario involves a closed cat in a box attached to a random subatomic event that may or may not occur. If this subatomic event occurs, the cat is dead, otherwise it is alive. As long as you don't open the box, you can't know the state of the cat, which in a closed box can be both alive and dead. This is defined as the state of a quantum superposition.. Schrodinger coined the term Verschränkung (or quantum entanglement) in the development of a thought experiment.

The phenomenon of entanglement violates the "principle of locality", for which what happens in one place cannot immediately affect what happens in another. Here's an example: two particles are ejected in opposite directions. If the particle A, during its journey, meets a magnetic field that deflects upward, the particle B, instead of continuing its trajectory in a straight line, simultaneously deflects the direction, taking the movement against its twin. This experiment shows that particles are able to communicate with each other, transmitting and processing information, and also shows that communication is instantaneous.

In October 1998, the phenomenon of entanglement was finally confirmed by the success of an experiment conducted by the Institute of Technology (Caltech) in Pasadena, California. In conclusion, microscopic quantum mechanics has led us to abandon the description of classical deterministic physics in order to obtain a probabilistic description in which the state and properties of the microcosm are not defined,a priori, in their essence, but acquire reality only if they are measured, and or if they come into contact with other "objects".

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