Complex systems are characterized by randomness and disorder and are difficult to understand. This year’s Nobel Prize in Physics recognizes new methods for describing and predicting their long-term behavior.
Syukuro Manabe and Klaus Hasselmann have been jointly awarded half of the 2021 prize “for physical modeling of the Earth’s climate , quantifying variability and reliably predicting global warming.”
Giorgio Parisi has been awarded half of the 2021 Nobel Prize in Physics “for the discovery of the interaction of disorder and fluctuations in physical systems from the atomic to the planetary scale.”
Understanding climate change
A complex system of vital importance to humanity is the Earth’s climate. Syukuro Manabe demonstrated how increased levels of carbon dioxide in the atmosphere lead to increased temperatures on the Earth’s surface. 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 vertical transport of air masses. His work laid the foundation for the development of current climate models.
About ten years later, Klaus Hasselmann created a model that links weather and climate, thus answering the question of why climate models can be reliable even though the climate is changeable and chaotic. He also developed methods to identify specific signals, a kind of fingerprints, that both natural phenomena and human activities imprint on the climate. Their methods have been used to show that the increase in temperature in the atmosphere is due to human emissions of carbon dioxide .
Around 1980, Giorgio Parisi discovered hidden patterns in messy 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 seemingly completely random materials and phenomena, not only in physics but also in other very different areas, such as mathematics, biology, neuroscience, and machine learning.
“ The discoveries that are being recognized this year demonstrate that our knowledge of climate rests on a solid scientific foundation, based on rigorous analysis of observations. All of this year’s awardees have contributed to us gaining a deeper insight into the properties and evolution of complex physical systems, ”says Thors Hans Hansson, Chairman of the Nobel Committee for Physics.
