Quantum Mechanics: Mind-Blowing Facts Unveiled

Quantum mechanics Smartphones contain billions of transistors that provide all the features for controlling currents and voltages.

In Quantum mechanics, Heisenberg's Uncertainty Principle sets scaling limits for the values of physical quantities!

Quantum mechanics is the physical theory that describes the behavior of matter and radiation and their mutual interactions, with special consideration being given to phenomena characteristic of the length scale or to atomic and subatomic energy, where earlier classical theories are inadequate.

What is quantum mechanics in simple terms?

As a fundamental feature, quantum mechanics describes radiation and matter as wave phenomena and particle entities, in contrast to classical mechanics, which describes light only as a wave and, for example, the electron only as a particle.

This unexpected and counterintuitive property of physical reality, called wave-particle duality, is the main reason for the failure of theories developed up to the nineteenth century to describe atoms and molecules. The relationship between wave and particle nature is stated in the integral principle and formalized in Heisenberg's uncertainty principle.

There are many mathematical equivalents of the theory, such as wave mechanics and matrix mechanics, on the contrary, there are numerous and contradictory interpretations regarding the ultimate essence of the universe and nature, which have led to a debate that is still open in the field of philosophy of science.

Quantum mechanics, along with the theory of relativity, represents a watershed in classical physics that gave birth to modern physics, and through quantum field theory, the generalization of the original formula, which includes the principle of special relativity, is the basis of many other branches of physics, such as physics Atomic, condensed matter physics, nuclear physics, particle physics, quantum chemistry.

history of quantum mechanics

At the end of the nineteenth century, mechanics appeared unable to describe the behavior of matter and electromagnetic radiation on the length scale of the arrangement of the atom or the energy scale of interactions between atoms, in particular, the empirical truth of light and the electron was inexplicable.

This restriction of classical laws was the main impetus that in the first half of the twentieth century led to the development of new physics quite different from those developed up to then, through a theory obtained through the combination of a set and its setting.

Theories formulated at the turn of the nineteenth and twentieth centuries, often of an empirical nature, based on the fact that some quantities at a microscopic level, such as energy or angular momentum, can differ only by discrete values ​​called "quantities" (hence The name "quantum theory" was given by Max Planck at the beginning of the twentieth century).

The crisis of classical physics and the search for a new theory

Atoms were recognized by John Dalton in 1803 as the basic components of molecules and all substances. In 1869, the periodic table of the elements made it possible to group atoms according to their chemical properties, which allowed the discovery of periodic laws, such as the octet rule, whose origin was unknown.

The studies of Avogadro, Dumas, and Gauden showed that atoms assemble themselves to form molecules, organizing and combining them according to laws of a geometric nature.

Not all of these discoveries explain why elements and molecules are formed according to these regular and periodic laws.

The basis for the atom's internal structure was laid instead with the discoveries of the electron in 1874 by George Stoney, and the nucleus by Rutherford. According to Rutherford's model, an atom's positively charged central nucleus acts on negative electrons in the same way that the Sun does on the solar system's planets.

However, the electromagnetic emissions predicted by Maxwell's theory of electric charges in accelerating motion should have had such a great intensity that the atom would collapse in a few moments, unlike the stability of all observed materials.

Electromagnetic radiation was theoretically predicted by James Clerk Maxwell in 1850 and was discovered experimentally by Heinrich Hertz in 1886.

However, Wayne discovered that according to the classical theory of the time, a black body capable of absorbing all incident radiation should emit electromagnetic waves of unlimited intensity and short wavelengths. This devastating paradox, although not immediately considered of great importance, was called the "Ultraviolet Disaster" in 1911.

In 1887 Heinrich Hertz discovered that the electric discharge between two charged conductive objects is more intense if the objects are exposed to ultraviolet light. This phenomenon, due to the interaction of electromagnetic radiation and matter, was called the photoelectric effect, and it was found that it inexplicably disappeared completely for the frequencies of the incident radiation below the threshold value, regardless of the overall intensity of this.

Moreover, if the photoelectric effect occurs, the energy of the electrons emitted by the conducting plates is directly proportional to the frequency of the electromagnetic radiation.

Such empirical evidence cannot be explained by Maxwell's classical wave theory. For a theoretical explanation of these counter-intuitive properties of light, Einstein was awarded the Nobel Prize in Physics in 1921.

Quantum mechanics, which has developed with the contributions of many physicists over more than half a century, has been able to provide a satisfactory explanation for all these rules of thumb and contradictions.

The birth of the quantum theory

In 1913, the Danish physicist Niels Bohr proposed an experimental model to try to gather evidence on the stability and emission spectrum of the hydrogen atom, such as the Rydberg equation.

Max Planck, Albert Einstein, Peter Debye, and Arnold Sommerfeld contributed to the development and popularization of the formal set of rules proposed by Bohr, which is referred to as an ancient quantum theory.

In this model, the movement of the electron in the hydrogen atom is allowed only along a discrete set of fixed and closed circular or ellipsoidal orbitals.

Electromagnetic radiation is absorbed or emitted only when an electron successively passes from a smaller orbit to a larger orbit or vice versa.

However, it has not been clarified why the electron can only travel on some specific closed paths.

In 1924 the French physicist Louis de Broglie hypothesized that the electron, in addition to the particle, also has an undulating behavior, which is manifested, for example, by the phenomenon of interference.

In this way, Bohr's quantum law can be interpreted simply as the state of standing waves, the equivalent of waves that develop on the vibrating string of a violin.

The development of quantum mechanics

Based on these results, Werner Heisenberg and Erwin Schrödinger 1925-1926 developed matrix mechanics and wave mechanics, two different formulations of quantum mechanics that lead to the same results. The Schrödinger equation in particular is similar to the wave equation and its constant solutions represent the possible states of particles and thus also of electrons in a hydrogen atom.

The nature of these waves was immediately the subject of considerable debate, which has continued to some extent to this day.

In the second half of the 1920s, the theory was formalized, with the adoption of basic assumptions, by Paul Adrian Maurice Dirac, John von Neumann, and Hermann Weil.

A representation that is still different, but leads to the same results as the previous ones, called integration on paths, was developed in 1948 by Richard Feynman: a quantum particle traversing all possible paths during its motion, and the different contributions made by each path overlap each other to generate behavior. Most likely it is noticed.

importance of quantum mechanics

Quantum mechanics is incredibly popular. No prediction developed by the theory has been proven wrong. A third of our economy depends on the products you depend on. However, the worldview derived from quantum theory is not only more exotic than we can imagine, but it is also even stranger than we can suppose. Let's find out why.

Many of us share the following common sense insights: no single being can exist in two distant places at the same time; what a person decides to do cannot immediately affect what happens in a remote place.

Shouldn't we assume that there is a real world "out there", whether you look at it or not? Quantum mechanics questions each of these ideas.

Jauch says that "for many thinking physicists, (the deeper meaning of quantum mechanics; Ed.) it has always remained a kind of skeleton in the closet".

We started by talking about the nagging doubts about quantum theory that troubled Einstein.

Quantum theory is the basis of every natural science, from chemistry to cosmology. We need to understand why the sun shines, how television produces images, why the grass is green, and how the universe has expanded since the Big Bang. Modern technology relies on tools designed with quantum theory.

Pre-quantum physics also called "classical mechanics", "classical physics" or, more often, "Newtonian physics", is usually an excellent approximation for explaining the behavior of objects much larger than particles, and is in principle very much compatible. Easier to apply than quantum theory.

However, this is an approximation. It doesn't make sense to describe the atoms that makeup everything at all. However, classical physics is fundamental to our common sense, and to Newton's concept of reality. But we now know that the classic concept of reality is fundamentally flawed.

Since ancient times, philosophers have made esoteric speculation about the nature of physical reality.

Before quantum mechanics, everyone had the logical choice to reject such speculations and stick to a worldview based on realism and common sense. Today, quantum experiments deny the existence of physical reality based on common sense. Rejection is no longer a reasonable option.

Could the concept of the world proposed by quantum mechanics be relevant even outside of science? Think of earlier discoveries that had a similar effect, such as Copernicus's hunch that the Earth was not at the center of the universe or Darwin's theory of evolution. The importance of quantum mechanics is, in a sense, more compelling than Copernican or Darwinian ideas, which deal with things very far or very ancient.

Quantum theory is about the here and now. Rather, she comes to know the essence of humanity, our conscience.

Quantum Effects

Many experiments have confirmed or allowed us to guess the nature of matter and radiation on the microscopic scales described by quantum mechanics.

Many of these experiments led to the discovery of quantum effects, which are often counterintuitive to classical mechanics. Historically, the photoelectric effect and the study of black-body spectroscopy were among the first experiments to prove the quantum nature of the electromagnetic field, leading to the discovery, theoretical formulation, and verification of the photon. from Planck, which according to the energy of the photons is proportional to their frequency.

On the other hand, the spectrum of the hydrogen atom first led to the development of the Bohr-Sommerfeld atomic model and then made it possible to formulate and verify the Schrödinger equation.

The tunneling effect consists of the possibility that an electron can overcome a potential barrier even if it does not have the energy to do so, which is denied by classical mechanics. Quantum entanglement experiments have been instrumental in rejecting the EPR paradox.

Recently, superconductivity and superfluidity have attracted increasing interest in potential technological developments, phenomena studied by condensed matter physics. Instead, the Casimir effect has been central to understanding the quantum fluctuations of fields in a vacuum and is related to the discovery of vacuum energy.