3 scientists win Nobel Prize in Physics for study of complex systems

Scientists Syukuro Manabe, Klaus Hasselmann and Giorgio Parisi won the 2021 Nobel Prize for Physics for their “groundbreaking contributions to our understanding of complex physical systems”.

Syukuro Manabe, 90, and Klaus Hasselmann, 89, were cited for their work in the physical modeling of Earth’s climate, quantifying variability and reliably predicting global warming.

The second half of the prize was awarded to Giorgio Parisi, 73, for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales.

The three winners:

• Syukuro Manabe was born in 1931 in Shingu, Japan. He got Ph.D in 1957 from University of Tokyo. He is a Senior Meteorologist at Princeton University in the US.

• Klaus Hasselmann was born 1931 in Hamburg, Germany. He got Ph.D in 1957 from University of Göttingen, Germany. He is a professor in Max Planck Institute for Meteorology, Hamburg, Germany.

• Giorgio Parisi was born 1948 in Rome. He got Ph.D in 1970 from Sapienza University of Rome. He is a professor at Sapienza University of Rome.

• The three laureates share this year’s Nobel Prize in Physics for their studies of complex phenomena. Manabe and Hasselmann laid the foundation of our knowledge of the Earth’s climate and how humanity influences it. Parisi is rewarded for his revolutionary contributions to the theory of disordered and random phenomena.

Understanding complex physical systems

• Complex systems are characterised by randomness and disorder and are difficult to understand. This year’s Prize recognises new methods for describing them and predicting their long-term behaviour.

• All complex systems consist of many different inter-acting parts. They have been studied by physicists for a couple of centuries, and can be difficult to describe mathematically – they may have an enormous number of components or be governed by chance. 

• They could also be chaotic, like the weather, where small deviations in initial values result in huge differences at a later stage. 

• This year’s laureates have all contributed to us gaining greater knowledge of such systems and their long-term development.

• One complex system of vital importance to humankind is Earth’s climate.

• Syukuro Manabe demonstrated how increased concentrations of carbon dioxide in the atmosphere lead to increased temperatures at the surface of the Earth. In the 1960s, he led the development of physical models of the Earth’s climate and was the first person to explore the interaction between radiation balance and the vertical transport of air masses. His work laid the foundation for the development of climate models.

• About 10 years later, Klaus Hasselmann created a model that links together weather and climate, thus answering the question of why climate models can be reliable despite weather being changeable and chaotic. He also developed methods for identifying specific signals, fingerprints, that both natural phenomena and human activities imprint in the climate. His methods have been used to prove that the increased temperature in the atmosphere is due to human emissions of carbon dioxide.

• Around 1980, Giorgio Parisi discovered hidden patterns in disordered complex materials. His discoveries are among the most important contributions to the theory of complex systems. They make it possible to understand and describe many different and apparently entirely random complex materials and phenomena, not only in physics but also in other, very different areas, such as mathematics, biology, neuroscience and machine learning.

• The discoveries being recognised this year demonstrate that our knowledge about the climate rests on a solid scientific foundation, based on a rigorous analysis of observations.

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