John Otto Kessler died on September 2, 2022 in Tucson, Arizona at the age of 93. It was a great life, a lucky life, a life of purpose, imagination, curiosity and wonder. It was also a life of good humor, puns, sly smiles and winks. Jean loved life. If offered a new adventure, a new opportunity, or something new, John’s standard response was “of course.” He loved to tell stories and did so with wit and joy. He enjoyed making connections, which led to a life of creativity as well as groundbreaking research. John was born in Vienna, Austria on November 26, 1928 and lived in Austria with his parents, Jacob (Jacques) Kessler and Alice (Lizzy) Blanca Kessler (née Neuhut) until he was 10 years old. In 1938, his family was forced to flee Austria after his father was arrested by the Nazis on Kristallnacht. They lived in England for over a year before immigrating to the United States in 1940. After attending boarding school in Connecticut for a year, John moved to Jacksonville, Florida to be with his parents. In his senior year, he won honorable mention in a national science competition and as a result received a full scholarship to attend Columbia University in New York. He obtained a doctorate. in physics in 1953. In 1950, he married Eva Bondy; they had two children, Helen and Steven. John was proud of his many jobs growing up, as a paperboy, department store window dresser, and brewery chemist. His first job after college was with the Radio Corporation of America (RCA) in Princeton, NJ. In 1966 the family moved to Tucson, AZ, where John became a professor of physics. John’s Ph.D. research focused on high-energy particle physics. At RCA, his job completely changed, and once at the University of Arizona, he changed again. The last 40 years of his research have focused on biophysics, swimming microorganisms and fluid dynamics. He enjoyed hiking and was particularly fond of the desert and mountains of Tucson, the rugged coastline of northern California and southern Oregon, and the redwood forests. He also loved his research and the study of tiny algae and bacteria that looked almost like his friends. Moreover, he loved to travel and always visited art museums wherever he went. If there were Gothic churches or castles, so much the better. He had friends, relatives and colleagues all over the world, his closest colleagues being mainly in the UK. John’s wife, Eva, predeceased him in 2014. He is survived by their children, Helen and Steven, his daughter-in-law, Anne, and grandchildren, Matthew and Madelyn. He will be sadly missed by his many friends and family, including many wonderful friends from the Atria Campana del Rio retirement community where he and Eva moved 10 years ago. If you would like to make a donation in John’s honor, please consider the US Holocaust Memorial Museum (Washington, DC), Arizona Jewish Historical Society (Phoenix), Friends of Catalina State Park, Humane Society or Arizona Public Media. Commemorations will be held Dec. 1 at Atria Campana del Rio and Dec. 2 at Catalina State Park. Please email [email protected] for details.