In May 1925, in Göttingen, Heisenberg began to describe atomic systems by observables only (“quantum-theoretical” Fourier series). Werner Heisenberg (right) at CERN in 1960 with Giuseppe Fidecaro (left) and Edoardo Amaldi.

Heisenberg and Pauli claimed that fundamental concepts of the old theory, notably electron orbits, had to be abandoned completely. As a way out of the situation, Pauli, who was in Copenhagen, and Born and Heisenberg who were in Göttingen, proposed replacing the semiclassical differential expressions of Bohr and Sommerfeld by corresponding discrete difference terms to predict experimental quantum results (the 1925 Kramers Heisenberg formula, which predicted the Raman effect, for example). In 1923, contemporary atomic theory was in a deep crisis. In spite of this brilliant work, he nearly failed the experimental part of the doctoral exam with Willy Wien. On the publication of Heisenberg’s first paper in this field in 1922, Sommerfeld remarked to Heisenberg’s father: “You belong to an irreproachable family of philologists, and now you have the misfortune of seeing the sudden appearance of a mathematical-physical genius in your family.” In his PhD thesis, Heisenberg suggested the first method for deriving the critical Reynolds number, marking the transition from laminar to turbulent motion. Simultaneously he studied the classical hydrodynamical turbulence problem. The freshman found a perfect solution – exhibiting, however, unusual half-integral quantum numbers and a strangely behaving atomic core. In the very first semester Sommerfeld gave Heisenberg the difficult problem of explaining the anomalous Zeeman effect of sodium spectral lines. Thus he became a member of the great international post-First World War community of quantum and atomic theorists, including such brilliant talents as Paul Dirac, Enrico Fermi, Friedrich Hund, Pascual Jordan, Oskar Klein, Hendrik Kramers, Wolfgang Pauli and Gregor Wentzel. In 1924 Niels Bohr invited him to Copenhagen. He studied under Arnold Sommerfeld at the University of Munich, obtaining his PhD in July 1923 and then went on to work under Max Born in Göttingen. Werner Heisenberg, born in Würzburg, came from an academic family and after 1910 grew up in Munich, where he graduated with distinction from high school in 1920. He also established several fundamental quantum mechanics applications and pioneered the extension of the theory to high-energy phenomena. His famous uncertainty relations were a central part of its interpretation. It is to him that we owe the first breakthrough of modern atomic theory – the invention of quantum mechanics. This year, 5 December marks the centenary of Werner Heisenberg’s birth. Fame through uncertainty: quantum mechanics pioneer Werner Heisenberg in the 1920s. Helmut Rechenberg, Heisenberg’s last postgraduate, co-editor of his collected works and co-author of the multivolume opus The Historical Development of Quantum Theory, traces the life of a quantum figurehead. In short: the uncertainty principle describes a trade-off between two complementary properties, such as speed and position.This year marks the centenary of the birth of Werner Heisenberg, pioneer of quantum mechanics and theoretical high-energy physics. Conversely, if we wanted to know the exact position of one peak of a wave, we would have to monitor just one small section of the wave and would lose information about its speed.

The location is spread out among the peaks and troughs. The more peaks and troughs that pass by, the more accurately we would know the speed of a wave-but the less we would be able to say about its position.

To measure its speed, we would monitor the passage of multiple peaks and troughs. To understand the general idea behind the uncertainty principle, think of a ripple in a pond. Quantum objects are special because they all exhibit wave-like properties by the very nature of quantum theory. Though the Heisenberg uncertainty principle is famously known in quantum physics, a similar uncertainty principle also applies to problems in pure math and classical physics-basically, any object with wave-like properties will be affected by this principle. In other words, if we could shrink a tortoise down to the size of an electron, we would only be able to precisely calculate its speed or its location, not both at the same time. Formulated by the German physicist and Nobel laureate Werner Heisenberg in 1927, the uncertainty principle states that we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy the more we nail down the particle's position, the less we know about its speed and vice versa.

Werner heisenberg atomic theory