Max Planck(1858 — 1947)

Mathematical formula precisely describing the radiation emitted by a heated body, introducing for the first time the constant h (Planck's constant). This law constitutes the starting point of all modern quantum physics.

Revolutionary proposition that energy is not continuous but emitted in small discrete portions called quanta. This idea, which Planck himself considered provisional, would overturn the whole of twentieth-century physics.

Reference work synthesising Planck's research on thermodynamics prior to his discovery of quanta. It was used as a textbook in German universities for decades.

Book in which Planck systematically sets out his quantum theory of radiation. He formalises the introduction of the universal constant h = 6.626 × 10⁻³⁴ J·s, since named the 'Planck constant'.

Philosophical essay in which Planck reflects on the foundations of scientific knowledge and realism in physics. He argues that science seeks to grasp an objective reality independent of the observer.

Posthumous memoir in which Planck retraces his intellectual journey and the circumstances that led him to quantum theory. An irreplaceable document for understanding the genesis of one of the greatest scientific revolutions.

If this relation is exact, then the radiation constant b can be expressed as a function of the quantities h and k... the elementary energy ε must be proportional to the frequency of vibration.

We consider the energy E of a resonator as being composed of a finite integer number of equal parts, and we make use for this of the natural constant h = 6.55 × 10⁻²⁷ erg·s.

It was an act of despair. By nature, I am peaceful and averse to dubious adventures. But I had struggled for six years against classical thermodynamics without result. I had to find a theoretical explanation at all costs.

The discovery of the quantum hypothesis led to the idea that in nature there exists a fundamental discrete quantity, the constant h, which sets a limit to the indivisibility of physical processes.

Planck taught theoretical physics there from 1889 to 1926, making Berlin the world center of theoretical physics. It was in this setting that he developed his quantum theory.

Max Planck's birthplace, where he was born on April 23, 1858, into a cultivated Prussian bourgeois family. 19th-century Prussia placed great value on education and the sciences.

Planck studied physics there and defended his doctoral thesis in 1879. It was there that a professor advised him against pursuing physics, believing that everything had already been discovered.

It was before this learned society that Planck presented his revolutionary formula on December 14, 1900, a date considered the birth of quantum physics.

The city where Planck took refuge after his Berlin home was destroyed, and where he died on October 4, 1947. Göttingen was at the time a major center of German mathematics and physics.