Introduction to quantum mechanics: Max Planck (full version)

Usually, when we hear of so-called quantum physics, it is common for an idea of strangeness to be attached to it, often challenging our perception of everything around us. But what would be the reason for such an exotic fame of quantum theory? We will discuss the behavior of this different universe throughout this and other articles.

The "birth" of quantum theory, often called quantum mechanics by the most intimates, was given to physicist Max Planck in 1900/1901. At the time, the scientist was working to solve a disturbing question in physics: the problem of ultraviolet catastrophe. This question implied that a black body (ideal body that absorbs all the radiation in it) should emit radiation with infinite energy, which did not agree with experiments. Following classical electromagnetism, experimental results fit the classical theory only for radiation with large wavelengths (reddish lights in the visible range of the spectrum) but implied infinite radiation for small wavelengths, which in itself is a violation of one of the most important laws of all science, the law of conservation of energy. Thus (along with other motives) it was seen that classical theory presented fundamental problems and was not sufficient to describe our universe.

The Max Planck solution: The German physicist proposed at the beginning of the twentieth century the quantization of energy in terms of its frequency, that is, energy could not assume any arbitrary value, but rather, values ​​proportional to their frequency. The discrete values ​​of energy / "energy packets" are commonly called quanta. The mathematical formulation defined by Planck is marked in the minds of all students of physics:

E = hf

Where f is the frequency and h is Planck's famous constant, abundantly used throughout quantum theory. The value of the constant is approximately 6,626 × 〖10〗 ^ (- 34) J ∙ s in the SI.

With Planck's theory, we see the famous wave-particle duality (in certain cases the light shows an undulatory behavior and in other corpuscular) which was also present in the explanation of the photoelectric effect, a phenomenon that guaranteed Einstein his Nobel Prize.

At the end of his work, Max Planck had accidentally started a completely new branch of science: quantum mechanics. Over the years, several names have emerged with this new area of ​​research, such as Paul Dirac, Werner Heisenberg, Wolfgang Pauli, Richard Feynman, Erwin Schrödinger (with his famous mental experiment "Schrödinger's cat") among others. Quantum was known as the "science of the young," since most of the scientists who worked with it at the time were young. As the theory gained form, ramifications arose (like the quantum field theory) and the "experimental bizarre" came to prominence.

At the heart of the "quantum realm", everything is probabilistic, in the most elementary way possible. We commonly deal with probability issues in our day-to-day life, as when we calculate with what probability a dice will fall with one face up. However, at the heart of the question, the outcome of which face of the dice will be exposed is not probabilistic, but deterministic. If we consider multiple variables, such as air resistance, aerodynamics of the dice, the way it was released, among other things, we will have a precise answer about the result that the dice will give us. Quantum mechanics is probabilistic in itself and not due to our lack of information regarding the considered system (as in the analogy of the given). When we come across such a phrase, confusion can arise, so it is advisable to re-read it calmly, since the essentially probabilistic question is one of the pillars of quantum mechanics.

An interesting fact is that Albert Einstein made clear his imposition on this rising theory, exhibiting his disbelief that the building blocks of the universe (particles) have an indispensable / random behavior. Einstein commonly attempted to refute the ideas of quantum mechanics by proposing explanations with a deterministic view of phenomena, but experiments (such as Bell's inequalities) confirmed the quantum version.

Nowadays, quantum mechanics is indispensable in our routines, even though sometimes we do not realize it. It is through this that the engineering could evolve allowing the creation of semiconductors (devices widely used in electronic equipment), lasers, etc. So if today you have a cell phone, computer, or any electronic equipment thank the scientists of the twentieth century!

In future articles I will explore some of the quantum bizarrices, such as the fact that we can not know the position and velocity of a particle at the same time, which is called the Heisenberg uncertainty principle.

Reference Material: "A Brief History in Time" and "Brief Answers to Big Questions" (Stephen Hawking`s books)