Per Bak (8 December 1948 – 16 October 2002) was a Danish

theoretical physicist Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict natural phenomena. This is in contrast to experimental physics, which uses experi ...

who coauthored the 1987 academic paper that coined the term " self-organized criticality."

Life and work

After receiving his Ph.D. from the

Technical University of Denmark The Technical University of Denmark (), often simply referred to as DTU, is a polytechnic university and school of engineering. It was founded in 1829 at the initiative of Hans Christian Ørsted as Denmark's first polytechnic, and it is today ran ...

in 1974, Bak worked at

Brookhaven National Laboratory Brookhaven National Laboratory (BNL) is a United States Department of Energy national laboratories, United States Department of Energy national laboratory located in Upton, New York, a hamlet of the Brookhaven, New York, Town of Brookhaven. It w ...

. He specialized in

phase transition In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic Sta ...

s, such as those occurring when an insulator suddenly becomes a conductor or when water freezes. In that context, he also did important work on complicated spatially modulated (magnetic) structures in solids. This research led him to the more general question of how organization emerges from disorder. In 1987, he and two postdoctoral researchers, Chao Tang and Kurt Wiesenfeld, published an article in ''

Physical Review Letters ''Physical Review Letters'' (''PRL''), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. The journal is considered one of the most prestigious in the field of physics ...

'' setting a new concept they called self-organized criticality. The first discovered example of a

dynamical system In mathematics, a dynamical system is a system in which a Function (mathematics), function describes the time dependence of a Point (geometry), point in an ambient space, such as in a parametric curve. Examples include the mathematical models ...

displaying such self-organized criticality, the Bak-Tang-Wiesenfeld sandpile model, was named after them. Faced with many skeptics, Bak pursued the implications of his theory at a number of institutions, including the Brookhaven National Laboratory, the

Santa Fe Institute The Santa Fe Institute (SFI) is an independent, nonprofit theoretical research institute located in Santa Fe, New Mexico, United States and dedicated to the multidisciplinary study of the fundamental principles of complex adaptive systems, inc ...

, the

Niels Bohr Institute The Niels Bohr Institute () is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics, and biophysics. Overview The institute was foun ...

in Copenhagen, and

Imperial College London Imperial College London, also known as Imperial, is a Public university, public research university in London, England. Its history began with Prince Albert of Saxe-Coburg and Gotha, Prince Albert, husband of Queen Victoria, who envisioned a Al ...

, where he became a professor in 2000. In 1996, he took his ideas to a broader audience with his ambitiously titled book, ''How Nature Works''. In 2001, Bak learned that he had

myelodysplastic syndrome A myelodysplastic syndrome (MDS) is one of a group of cancers in which blood cells in the bone marrow do not mature, and as a result, do not develop into healthy blood cells. Early on, no symptoms typically are seen. Later, symptoms may includ ...

and died from complications of a stem-cell transplant. Bak is survived by his second wife, Maya Paczuski, a fellow physicist and current professor at the

University of Calgary {{Infobox university , name = University of Calgary , image = University of Calgary coat of arms without motto scroll.svg , image_size = 150px , caption = Coat of arms , former ...

, with whom he has coauthored papers, and his four children.

Selected publications

* * * 1996, ''How Nature Works: The Science of Self-Organized Criticality'', New York: Copernicus. *

References

* {{DEFAULTSORT:Bak, Per 1948 births 2002 deaths Deaths from myelodysplastic syndrome People from Brønderslev Academics of Imperial College London Complex systems scientists 20th-century Danish physicists Brookhaven National Laboratory staff Fellows of the American Physical Society