Quantum mechanics - what is it and why is it needed?
Quantum mechanics was born as a necessity to explain the results of some experiments that classical theory could not explain.
First. Difficulties arose with Jung's experience. It was not clear how one and the same particle could crawl through two different slits at the same time. Wave-particle dualism was born, which cannot be imagined by anyone. Everyone should just believe it and remember it. So far, no other experiments confirming this dualism have been observed. Jung's experience and errors in its interpretation can be found in link .
The second incident arose with Rutherford's planetary model of the atom. When he presented his model, the sages immediately put forward a theory: an electron rotates at high speed around the nucleus, as a result of which it should emit energy and eventually fall onto the nucleus. And this electron did not fall anywhere and did not fly away anywhere. But either these sages forgot or did not know about Kaufman's experiments and the presence of a magnetic field at the core (maybe no one knew about it then), since they did not take all this into account in their reasoning.
Bohr had to postulate: the atom has levels (orbits) where the electron flies and does not emit anything. Everyone was dumbfounded and stopped looking for forces that would not allow the electron to fall on the nucleus, and they did not even think about the forces that hold the electron in the composition of the atom, and even now scientists do not even suspect that such forces exist in the form of an exchange photon.
Everyone rushed to prove the existence of such statements with mathematics. I just took a small list directly from Wikipedia. Particularly successful in this:
Many more could be added to this list.
The main thing is not to be intimidated by these formulas. In these formulas, the elements highlighted in pink are called the Hamiltonian. He describes the energy that is involved in solving this task. It can be potential energy, kinetic energy, elastic energy, etc. Here in the Schredinger Hamiltonian, the kinetic energy, for example, of an electron and the potential energy of a proton (electric field) are described. And under the differentials are the required functions, that is, for such and such a Hamiltonian, one must find a function that would satisfy this equation. Usually the solution is in the form of sines, cosines, and other oscillating functions. In general, a wave and a point. Wave function.
This problem for the hydrogen atom is solved by Richard Feynman in his lectures: "Volume 9. Chapter 17. The Hydrogen Atom and the Periodic Table." http://t-z-n.ru/archives/tom9.pdf. True, he makes an irreparable error - he excludes, or rather does not introduce into the Hamiltonian, the magnetic field of the proton, which just does not allow the electron to fall on the proton. Well, okay, no one understands this yet.
Then he grades the potential into certain areas with energy En=ER/n*2. Names the number n - the principal quantum number. For kinetic energy, the number l is introduced, as Feynman believes, it quantizes the orbital angular momentum.
Then he solves this equation and gives such results.
As you can see, there are waves everywhere. It is clear that the function is wave. But these are the waves of what? How is this wave related to the particle to explain the wave-particle duality? Does the wave relate to the very body of the electron, what does this very dualism require, or to the behavior of the electron, which does not in any way enter into dualism? It would be necessary to explain the dualism of the electron itself, without relative to where it is, and Feynman solves the problem - where it is, as a particle. Getting married and promising to marry are two different things.
I don't know how these theoretical calculations by Feynman fit into the series of Rydberg, Lyman, Balmer and others.
I have not found any other descriptions of anything yet. Yes, I think they are logical and it should not be. Indeed, if Feynman correctly described the hydrogen atom using the Schredinger equation, then any scientist who describes the hydrogen atom using the formulas of Neumann, Lindbad and others should necessarily obtain the same results.
For this reason, the statement that “ quantum mechanics adequately describes the basic properties and behavior of atoms, ions, molecules, condensed matter and other systems with an electron-nuclear structure ” (Wikipedia) seems highly doubtful.
Unfortunately, I cannot find and cannot imagine at least some significant area of phenomena where quantum mechanics could help solve anything.
You can imagine some involvement of the principles of this mechanics in the car structure. The car was already there, but there was no wave function. There may be steam locomotives or steamers, whose propellers are calculated using wave functions. All this was before the genius of Schredinger. Edison had no education at all, and his bulbs are shining. Then one should look for traces of the application of these functions in later phenomena? Rockets. Did Meshchersky or Tsiolkovsky use quantum mechanics, and even with necessity, as with laws? Oh, whether. And what about the computer? Boolean algebra has been and is being applied in computers, but dualism has not been applied to this day, although they are trying to build a quantum computer. Where, where can the ideology of quantum mechanics be applied? In the atomic field, in radio, in telecommunications, or in any other process of transmitting information or energy?
Name me at least one of the areas of being in which a scientist would sit and calculate the behavior of “atoms, ions, molecules”. Maybe it is in molecular biology that a scientist calculates how replication occurs, mitosis, vaccine parameters, and so on? Show a scientist who would be armed with a wave function, with the exception of teachers for whom the wave function is bread. It's easier to find the most disguised spy than the scientist.
In conclusion, we can say that such quantum mechanics, with its current laws, does more harm than good to humanity.