A Force of Nature: Jacob N. Israelachvili (1944-2018)

“Amontons’ Law doesn’t work”, Jacob Israelachvili stated recently, “…and anyway it wasn’t invented by Amontons”. He went on to denounce the Stribeck curve and the Archard equation in a similar vein, to an astonished audience hearing him over a video link at the World Tribology Congress in Beijing last year. Insightful, provocative and whimsical are three adjectives that come to mind to describe an individual who transformed our view of surface forces over the last few decades.

Jacob was born in Tel Aviv on 19th August, 1944, to parents of Polish and Georgian extraction. As the newly independent State of Israel was entering its early childhood, Jacob was shipped off to a British boarding school at 7 years of age. After flourishing in the highly specialized British educational system, Jacob, now convinced he was going to embark on a scientific or engineering career, went back to Israel to complete his mandatory military service before starting a degree in Physics (Natural Sciences) at Cambridge University, UK. Following his undergraduate studies, Jacob joined David Tabor’s group at the Cavendish Laboratory, and began his lifelong studies of surface forces. The instrument that he and others constructed at the Cavendish to measure van der Waals forces between surfaces became known as the surface forces apparatus (SFA), and it was destined to be the mainstay of his subsequent research activities.

After the Cavendish, Jacob took up a fellowship at the University of Stockholm, moving into the realm of biophysics with his study of molecular motions of lipids and membranes. In 1974 Jacob moved to the Australian National University in Canberra and returned to his earlier interest in surface forces, but this time focusing on their importance in a liquid environment, which later led him to study biological ligand-receptor interactions.

Jacob made a particularly groundbreaking observation with colleague Roger Horn in 1980, namely that there was an oscillatory force structure on a molecular scale that could be observed upon the compression of many liquids [1]. This “structuring under confinement” guides much of our thinking on liquid behavior at solid interfaces today, and led Jacob to propose molecular-level theories of friction, adhesion, and lubrication [2]. Jacob would go on to win the Gold Medal for Tribology in 2013.

After 12 years in Australia, Jacob made a move to the Chemical Engineering Department at the University of California, Santa Barbara, where he remained for the rest of his career, working in diverse areas ranging from chocolate to ionic liquids, and from mayonnaise to cartilage lubrication. The SFA remained the central tool of his research.

For many it has been Jacob, as a writer, teacher, or mentor, who has shaped their views on surface forces. In particular, his highly successful monograph “Intermolecular and Surface Forces”, which reached its third edition in 2011 [3], is encountered on many bookshelves in materials, engineering, and physics departments around the world, and describes fundamental concepts and equations of the field. Jacob also mentored generations of PhD students and postdocs, many of whom have themselves become noted researchers in the field of surface forces. Those of us who were lucky enough to know Jacob personally remember his bursts of creative insight and his broad knowledge of science and its history, but also his wicked sense of humor, his irreverent approach to sacred cows, and his love of limericks. Science has lost both a guiding light and a sparkling personality.

References:

1. Horn, Roger G., & Israelachvili, Jacob N. (1980). Direct measurement of forces due to solvent structure. Chemical Physics Letters, 71(2), 192-194.
   
2. Yoshizawa, Hisae; Chen, You-Lung and Israelachvili, Jacob N. (1993), Recent advances in molecular level understanding of adhesion, friction and lubrication, Wear 168 161-166
3. Israelachvili, Jacob N. (1992). Intermolecular and Surface Forces. Academic Press, Boston, ISBN 0-12-375181-0
   

Nicholas D. Spencer, ETH Zürich
Wilfred T. Tysoe, University of Wisconsin, Milwaukee