The historical context
We are between the end of the nineteenth century and the First World War . We have to imagine that everything is changing very quickly: electric lighting is coming , radio , cars , movies and many other comforts have been invented that make life easier for many people in the world.

This period is called the Belle Époque , from the French “beautiful era”, in which artists and scientists are abuzz in all the great capitals of Europe, everywhere there is an atmosphere of great optimism .

During the Belle Époque many thought that progress would solve all the problems of humanity!

Even the physical lives during these years his Belle Epoque: Scientists believe they have in their hands a complete view of the entire universe!

They think they can describe all natural phenomena due to three important theories: the Newtonian classical mechanics , which explains the movement of bodies , the ‘ electromagnetism explaining the electrical and magnetic phenomena and statistical mechanics . The latter is a recent and strange discipline, which wants to study how the characteristics change , for example pressure, volume and temperature, of a system made up of many particles (like a gas!).

As history teaches us, the answers often only lead to other questions …
And that’s what happened in the late nineteenth and early twentieth centuries.

In this period there is a great technological development that allows, slowly, to measure things that before were not measurable. For example, tools that allow measurements to be taken at very low temperatures, or to study what happens in almost empty conditions.

What we now take for granted, like the existence of atoms or the structure of molecules , was unknown or poorly understood at that time and the possibility of doing practical experiments allowed us to go deep into the study of how matter is made. surrounds us.

As observations got deeper, there were inconsistencies, phenomena that could not be explained by known physics …

The quirks of quantum mechanics
The concept of “how much” was introduced by Max Plank in 1900: to understand what quantums are (let us say below) we must start from the explanation of the paradox of the photoelectric effect : it is here that we can identify the birth of quantum mechanics.

The author of the discovery was the great scientist Albert Einstein who, for this theory, won the Nobel Prize for physics!

To explain to us what the photoelectric effect is and the resulting paradox we contacted Paolo Umari who, at the University of Padua , deals with matter physics and teaches quantum mechanics.

“To begin with, we need to understand what electromagnetic radiation is . If we think of a metallic object heated on the fire we know that, after a while, it becomes incandescent and luminous . This emitted light is its own electromagnetic radiation. “

It was seen that by taking a piece of metal and sending electromagnetic radiation on it, some electrons could be seen escaping from the metal. This only happened if the frequency of light exceeded a certain value and this contradicted the theories related to classical physics.