# Eshel Ben-Jacob

Eshel Ben-Jacob (full name Eshel Refael Ben-Jacob Breslav; Hebrew: אשל רפאל בן-יעקב 13 April 1952 – 5 June 2015), was a theoretical and experimental physicist at Tel Aviv University, holder of the Maguy-Glass Chair in Physics of Complex Systems, and Fellow of the Center for Theoretical Biological Physics (CTBP) at Rice University. During the 1980s he became a leader in the theory of self-organization and pattern formation in open systems, later extending this work to adaptive complex systems and biocomplexity. In the late 1980s, he turned to study of bacterial self-organization, He developed new pattern forming bacteria species, becoming a pioneer in the study of bacterial intelligence and social behaviors of bacteria.

## Birth and early years

Eshel Ben-Jacob was born on April 13, 1952, in Haifa Israel into a family of pioneers that immigrated to Israel in the 1930s. After graduating from high school, he matriculated to study physics and mathematics at Tel Aviv University and was drafted to the Israeli Navy two years later. He completed his B.Sc., M.Sc. and most of his PhD studies during the service (1972–1980) first in the Navy Weather Forecast unit and later in the Navy Intelligence.

## Academic education and career

Ben-Jacob received a B.Sc. degree (1975) in physics from Tel Aviv University, a Certificate in System Analysis (1976) from the Technion (Israel Institute of Technology), and a M.Sc. degree (1978) (under the supervision of Y. Imry) and a PhD degree in physics (1982) (under the supervision of Y. Imry and D. J. Bergman) from Tel Aviv University. After three years (1981–1984) of postdoctoral research at the Kavli Institute for Theoretical Physics in Santa Barbara, he joined the Physics Department at the University of Michigan (1984–1989). Since 1986, he has been a faculty member of the School of Physics and Astronomy at Tel Aviv University (full Professor since 1992 and the holder of the Maguy-Glass Chair in Physics of Complex Systems since 2003).
Ben-Jacob was vice president (1998–2001) and president (2001–2004) of the Israel Physical Society. Since 2005, he has been a fellow of the Center for Theoretical Biological Physics, Rice University. He was elected to the American Philosophical Society in 2014 as an International Member in the Physical Sciences Class.

## Contributions in physics

* Life time and dynamics of non equilibrium states.
* Coulomb Effect, Coulomb staircase and single electron-based transistor.
* Quantum dynamics of relativistic solitons.
* Soliton-mediated protein folding.
* Pattern formation and self-organization.

## Contributions in biological physics
### Social behavior of bacteria

In the early 1990s, Ben-Jacob's group discovered two pattern-forming bacteria species—the Paenibacillus dendritiformis and the Paenibacillus vortex (see also Paenibacillus). Combining microbiological experiments with physical principles of self-organization and advanced modeling, Ben-Jacob advanced the recognition that bacteria are smart cooperative organisms that employ advanced communication to lead intricate social lives in large and complex colonies. Sophisticated chemical communication allows bacteria to rapidly adapt to changes in the environment, distribute tasks, "learn from experience", make decisions and prepare for the future. Ben-Jacob put forward the idea of bacterial social intelligence and his group devised a social IQ score of bacteria as a comparative genomic tool to assess the genome potential of bacteria to conduct successful cooperative and adaptable behaviors, or social behaviors, in complex environments.

### Multi-agent swarming

Inspired by Ben-Jacob's observations of how bacteria can spontaneously order their motion during collective swarming, the groups of T. Vicsek and Ben-Jacob devised a simple model able to generate non-equilibrium states that violate the usual physics theorems for equilibrium states. This work has led to the creating of a new field of multi-agent swarming (swarming intelligence), proposed to explain a wide variety of phenomena ranging from collective navigation (swarming intelligence) of bacteria, amoeba and insects, to flocking of birds and schools of fish as well as to the design of autonomous vehicles capable of functional self-organization even in the absence of an overall omniscient controller. Using fratricide to fight bacteria: In 2000, Ben-Jacob's group discovered a fascinating phenomenon of competition between two sibling bacteria colonies of the P. dendritiformis when inoculated side by side. Recent studies of the phenomenon revealed that the two colonies not only inhibited each other from growing into the territory between them but induced the death of those cells close to the border. By employing molecular biology methods combined with the new genome sequencing information and bioinformatics, they discovered a new toxin (sibling lethal factor), which acts selectively only on the same bacterial strain.

### Bacterial decision-making

Building upon understanding he gained from research in neuroscience (the inhibition of inhibition principle), Ben-Jacob and his collaborators discovered that the ingenious scheme is composed of a stochastic switch regulated by a timer with adaptable clock rate (that is adjusted by the cell stress) via a special decision-circuit composed of a cascade of inhibitions. The decision-circuits of the individual bacteria are coupled by exchange of chemical messages between the cells to guarantee collective decision for the group benefit.

### Systems neuroscience and the neuro-memory-chip

Ben-Jacob's studies in neuroscience are guided by an effort to simplify the complexity searching for principles of information coding, memory and learning. He has many unique contributions in the field of Systems Neuroscience and Neural Networks, including the relations between network size and its synchronized activity, the discovery of hidden neuron correlations, function-form relations and mutual synchronization in engineered networks, the effect of DNA damage on network synchronization, neuro-glia communication, new modeling of intra- and inter-cell calcium dynamics, using nano technology for network engineering, discovery and modeling of the dynamical motives (repertoire) of coupled neural networks, development of a novel system-level analysis of neural network activity (the functional holography analysis), mapping and assessments of epileptic foci, and more. Yet, the development of the first neuro-memory-chip with his doctoral student at the time, Itay Baruchi, is Ben-Jacob's most important contribution in systems neuroscience. While previous attempts were based on "teaching by reward" (enhancing excitatory synapses) or "teaching by punishment" (inhibition of excitatory synapses), Baruchi and Ben-Jacob's approach was "teaching by liberation", or "inhibition of inhibition" (inhibition of inhibitory synapses). Being recognized as a groundbreaking discovery in systems neuroscience, the achievement was awarded in 2007 the SciAm 50, The Scientific American Award for the 50 most important achievements in all fields of science and technology.

## Immunology

Together with Irun Cohen from the Weizmann institute of science, Ben-Jacob has established the Immune Development Initiative (IDI), a multi-disciplinary research collaboration including of immunologists, physicists and physicians.

## Econophysics

In the field of the analysis of economic systems, he has published a new quantitative measure, the index cohesive force of the index effect on the stock market fragility.;on epileptic seizure-like behaviors in the US stock market; and hidden order in the market chaos. He developed a new class of correlation-based networks based on the concept of partial correlations. This led to the introduction of the dependency networks methodology. When applied to the U.S. stock market, it was successful in revealing the backbone of the market, quantitatively showing the dominance of the financial sector.

## Physics education

While serving as president of the Israel Physical Society (IPS), Ben-Jacob devoted efforts to attract teenagers to Physics by establishing links between high school physics teachers and the ISF (Israel Science Foundation). He appointed a high school principal, Tehila Ben-Gai of HEMDA Center for Science Education, as the Secretary of the ISF, and together they promoted joint annual scientific meetings between high school physics teachers and the ISF, faculty lectures to high school students, visits of high school classes in physics departments and more. During his presidency, he started the online magazine PhysicaPlus, the only Hebrew-English bilingual science magazine. Together with Tehila Ben-Gai and Haim Harary, they initiated a two-years high school course in computational science (called MOAH, 'brain' in Hebrew) aimed to elevate high school students' creativity and teamwork capabilities. Ben-Jacob served on HEMDA Executive Council and since 2010 he served as Chair of the Advisory Council of High School Physics Education of the Israeli Ministry of Education.