With deep sadness, we announce that on 21 January 2024, Hillar Aben, the long-time editor-in-chief of the Proceedings of the Estonian Academy of Sciences (1995–2007) and the chairman of the Estonian Academy of Sciences Publishing Council (1997–2007), passed away.

Hillar Aben was born on 3 December 1929 in Tartu, into a family of educators. After graduating from Tartu 1st High School (currently Hugo Treffner Gymnasium) in 1948, he enrolled at Tallinn University of Technology, graduating in 1953 as a civil engineer. In the same year, he entered the postgraduate programme, focusing on photoelasticity. In 1957, Hillar Aben defended his candidate dissertation (equivalent to a PhD today) titled ‘Solutions to Crustal Problems Using the Photoelasticity Method’ at the Estonian Academy of Sciences. His research in developing the optical theory of the photoelasticity method continued, leading to the defence of his doctoral dissertation, ‘The Method of Characteristic Directions in Photoelasticity,’ in 1966.

From 1956 to 1960, Hillar Aben worked as a junior researcher at the Estonian Academy of Sciences Institute of Construction and Building Materials. Subsequently, for nearly sixty years, he was associated with the Institute of Cybernetics, where he served as the head of the Mechanics and Applied Mathematics sector (1960–1974), deputy director of the research area (1967–1976), director (1976–1988), head of the Photoelasticity Laboratory (1989–2013), and leading researcher (2005–2016), later serving as a consultant in the Solid Mechanics Laboratory.

Under Hillar Aben’s leadership, the Photoelasticity Laboratory at the Institute of Cybernetics became an internationally renowned centre for research and development, particularly in the measurement of residual stresses inside glass. Together with colleagues, he developed a method and apparatus for determining internal stresses in complex-shaped glass products. This method, based on polariscope technology with sophisticated technical solutions and original software, is employed by nearly a hundred companies worldwide, including all major automotive glass manufacturers.

Hillar Aben’s contributions have been recognised with two Estonian State Science Prizes, including the highest accolade in 2009, the Discovery Prize, as the leader of a team that achieved innovative results. The recognition was for the development and application of the integrated photoelasticity method’s theory, measurement technology, and apparatus for measuring residual stresses in the glass industry.

In 2001, he was awarded the Order of the White Star, III Class, and in 2009, the Nikolai Alumäe Medal. In 2010, the Society for Experimental Mechanics in the United States bestowed upon Hillar Aben its highest honour – an invitation to deliver the William M. Murray Lecture and the accompanying medal.

Hillar Aben was a member of the European Academy of Sciences, the European Academy of Sciences and Arts, the Finnish Academy of Technical Sciences, and several international scientific societies. He worked as a visiting professor at the University of Waterloo in Canada, the University of Poitiers in France, and the Polytechnic Institute of Bari in Italy. In Estonia, he served on the Academic Council of the President of the Republic from 1994 to 2001 and was a member of the State Science Prizes Committee from 1999 to 2002. Additionally, from 1995 to 2007, he served as the editor-in-chief of the Proceedings of the Estonian Academy of Sciences.

Photo: collection of the Estonian Academy of Sciences