Good evening to all my dear friends, today, after a long absence, I would like to start a short journey (4 or 5 posts at most) in which I want to explain why the birth of quantum mechanics has changed the concept of "reality". Enjoy the reading :) ![](https://steemitimages.com/DQmboKjk23YWRVYGxbaFtG4jjAqWZWEcYJ2sREyoF1XKDoe/quantum-time-826886.jpg) Quantum mechanics is far more than a scientific theory. It was a real "conceptual earthquake" that posed serious philosophical problems, which are still largely open! Quantum mechanics is the most successful theory in the whole history of science. (1) It correctly explains the interaction between matter and radiation (QED). (2) It establishes the structure of the periodic table of the chemical elements, thus providing a very useful instrument for structural chemistry. (3) Has allowed the birth of electronics (semiconductors and superconductors). (4) It provided important help in studying astronomical objects (black holes). Let's make some history... **December 19, 1900: Max Planck and the issue of radiation of the black body** ![](https://steemitimages.com/DQmXnacRKJsh4Vyzm46xPdVDYdtDNTkok8MsHWR41hCDE1S/Image21b.gif) *Black body emission curves for different temperatures. As the temperature rises, the maximum moves toward the lower wavelengths.* Curves were unexplainable if applied to classical thermodynamics and electromagnetism. Planck then introduced a new idea *"For a pure act of despair"* However, Planck considered his solution as a pure mathematical model. It was the hypothesis of quantization of energy, energy exchanged for "packets" or "quantum" **E = n * h * v** Where n = positive integer h = Plank constant v = frequency At that time it was a heretical hypothesis, but someone else took it seriously, guess who? Yes your're right ;) Uncle Albert. ![Cattura.PNG](https://steemitimages.com/DQmV1xtaSPDZfgVfCtp8L542DVNBNagempDkqM4jUQLUEwV/Cattura.PNG) Einstein can be considered the true "Father" of quantum theory. **1905: annus mirabilis of the history of physics!** Einstein wrote and published an article for which he would be given of the Nobel Prize in 1921: **AN HEURISTIC POINT OF VIEW RELATED TO GENERATION AND TRANSFORMATION OF LIGHT** This, marks the birth of Wave–particle duality. n 1924 the situation became more interesting, thanks to the doctoral thesis of Louis de Broglie. ![Cattura.PNG](https://steemitimages.com/DQmNqW7Dw672EL2QZ2hQzVEWeYmPFKhjQhBXMkq3R5JtV8c/Cattura.PNG) Basic Idea: If light, which is a wave phenomenon, exhibits corpuscular behavior , why not think that the matter, typically of a corpuscolar nature, can not exhibit wave-like behavior? **ESSENTIAL ELEMENTS OF FORMALISM** (1) Given a physical system S, it is associated with Hilbert Hs space of its physical states. (2) Each A-size (observable) physical size is associated with an auto-coupled A* operator, whose eigenvalue equation provides the states and the possible values of that observable. ![](https://steemitimages.com/DQmYddRwqhbVsQdHLTRKpGAnw2KAsPd2V7hpqgUtr9FfJ94/immagine.png) (3) Considering a system S described by the state | Ψ> which is not a self-point of a observable B, the expression ![](https://steemitimages.com/DQmQmd9jQCNgL3AT1HEhZVRoxqZY7HR5Yt1uy9otcfKDdhG/immagine.png) Provides the probability that, in a measure ofB, you find the bn value (Born rule, 1926). **NOT EPISTEMIC PROBABILITIES!** (4) Once a system S is prepared in the state lΨ(0)>, it will evolve deterministically in time according to the Schrödinger equation ![](https://steemitimages.com/DQmbHWMpQ7jnNXvJP7F6v55aj3VxxRiwvWAaGqVsf9TCcdy/immagine.png) The linearity of the equation implies the Superposition principle. **Reduction of the Wave Package** Be S described by ![](https://steemitimages.com/DQmP7oHDv5xrJ1mtzPAbfioryBK2VDNoHepS6isFXiq3Jy3/immagine.png) If I measure A and I find a3, then after the measure will be: ![](https://steemitimages.com/DQmQvdQG4Eic7AA9AS5qK63jkEm75rLNcZkVFe1jmGakrFF/immagine.png) Max Planck introduced a whole new perspective: The wave function gives us the PROBABILITY to find, IF WE MEASURE IT, the particle in a given volume of space. The schroedinger equation is thus an equation that provides the evolution in time of a probability. **This is the first example in the history of a similar equation !!!!** Ok this first part is a bit heavy to digest, especially if you do not have a scientific education, but I hope the general concept is fairly clear. we will see tomorrow with the second part Dear friends, this thing will become much more interesting ;) Happy Steeming !!!!