Harold W. Hilsinger, 94, passed away peacefully at his home on Thursday, August 13, 2026, with his family by his side.  He is survived by his loving wife of 50 years, Barbara A. (Waite) Hilsinger; his daughter, Claire Hilsinger of Greenfield; his grandchildren, Calvin Hilsinger and Mary Hilsinger of Tampa, Florida; his nephew, Jeff Jacobs of New Jersey; as well as many cousins and friends. In addition to his parents, Harold was predeceased by his son, Aaron Hilsinger, and his sister, Marjorie Jacobs.

Harold was born in Midland, Michigan, son of the late Harold and Kathryn (Wheeler) Hilsinger. He graduated from Midland High School before attending the University of Michigan, where he earned his bachelor's degree. He went on to receive his doctorate in physics from the University of Connecticut and spent more than 36 years as a physics professor at Worcester Polytechnic Institute. He retired in 1998.

During their retirement, Harold and Barbara enjoyed traveling throughout the world. Among their many adventures, they visited Alaska, skied in Austria, the French and Swiss Alps, toured Italy, and made many trips to Florida to spend time with their grandchildren. Harold was an avid reader and a talented woodworker.

In their younger years, Harold and Barbara built a family cabin in New Hampshire, where they enjoyed hiking, camping, skiing and exploring the White Mountains. In 1975, they embarked on an extraordinary 4,600-mile bicycle journey across the United States, cycling approximately 60 miles each day and completing the trip in just 11 weeks. It was one of many adventures that created a lifetime of cherished memories for their family.

Services will be private.