Born in 1937 in Tallinn, Estonia, he spent most of his childhood in Stockholm and later moved with his family to Toronto as a young adult. Following his childhood love of airplanes, he earned his PhD in engineering physics and aerospace sciences from the University of Toronto in 1965. Soon after, Sonin joined MIT’s Department of Mechanical Engineering as an assistant professor; he retired in 2008.
Sonin served as the department’s graduate officer for 25 years. During his tenure, he earned him several teaching awards; he won the Graduate Student Council Teaching Award in 1973 and 1989 and the Ruth and Joel Spira Teaching Award in 1992. He guided students through academic and personal challenges with grace and dignity. His door was always open; his motto was, "We'll figure it out."
In the Spring 2010 issue of MechE Connects, the Department of Mechanical Engineering’s newsletter, Benny Budiman ScD ’04 recalled how Sonin helped him to cope with a family crisis without losing his academic momentum. “Professor Sonin was a tremendous resource to graduate students, guiding them through difficulties with grace and dignity,” Badiman said. “I have adopted ‘We’ll figure it out,’ as my own philosophy in facing challenges, personal and professional.”
Sonin taught undergraduate courses in fluid mechanics and thermodynamics, all the fundamental graduate-level subjects in fluid mechanics, and was especially well-known in the MIT community and beyond for his artfully crafted course in advanced fluid mechanics. His work and writings on the subject of dimensional analysis are considered the clearest exposition of the field and also the most useful for applying the concepts to modeling and real-world systems.
In addition to his long academic career, Sonin consulted frequently in both the private and government sectors including Thermo Electron Corp. in Waltham. He contributed articles to more than 70 publications and developed four patents — one for a water-desalination system and three for "sniffer" systems that are now in use at major airports and security checkpoints to detect drugs and explosives.
Sonin was a member of the American Society of Mechanical Engineers, American Physical Society, American Nuclear Society and American Association for the Advancement of Science. He also consulted for the Nuclear Regulatory Commission for 20 years.
He was dedicated to his family and their accomplishments. He was an avid jogger and biker and furniture designer.
Sonin is survived by his wife, Epp Karike Jurima Sonin; two sons: Juhan P. Sonin and his wife, Kathryn, of Arlington, Mass., and Aldo K. Sonin, of San Francisco; grandson Udo M. Sonin, of Arlington; mother Ina Sonin, sister Eda Sepp and family, all of Toronto.
Private family burial will be at Mount Auburn Cemetery. A memorial service will be in September 2010. In lieu of flowers, donations can be made to the MIT Department of Mechanical Engineering Ain A. Sonin Graduate Fellowship Fund.