Dr. Robert Greenler saw the world differently.
Where most people marvel at the beauty of a rainbow or a snowflake, Greenler was marveling at the physics behind them. He made it his life’s mission to help others look at the world with curious eyes.
Greenler, who served for 30 years as a faculty member in UW-Milwaukee’s Department of Physics, passed away on Sept. 21, 2025, at the age of 95. Not only was he a pioneer who led ground-breaking research into the optical properties of surfaces, but he also left behind a legacy of community science education at the university and in the Milwaukee community.
Greenler was the co-founder of Science Bag, a long-running program that explained a variety of scientific topics in fun, family-friendly ways. For decades, every Friday evening, Greenler and the UWM natural sciences faculty invited the Milwaukee community to learn about hurricanes, electricity, brain chemistry, and dozens of other topics. More than 150,000 people attended over the years. Science Bag is currently on hiatus but will be returning in a new format at some point in the future.
Greenler was known for giving a good lecture himself, said his colleague, UWM Physics Professor Emeritus John Friedman.
“Bob Greenler was a superb teacher, and his popular talks were as good as any I have seen,” Friedman said. “Among his many speaking invitations was one from the Royal Institution in London, to give a prestigious ‘Faraday lecture,’ a Friday Evening Discourse. Michael Faraday started this lecture series in 1826. Like Faraday, Greenler put great effort into creating demonstrations that dramatized the science he conveyed to a lay audience.”
It should be no surprise then, that in addition to Science Bag, Greenler left another legacy: The Dean’s Distinguished Lecture in the Natural Sciences. Hoping to share his love of the natural world and the science behind it, Greenler established a fund that would support an annual lecture, open to the Milwaukee community, that invited speakers to take a deep dive on a scientific topic of their choosing.
Greenler himself delivered the inaugural lecture in the spring of 2015. His talk, “Seeing with the mind as well as the eye,” walked his audience through how to use and strengthen their powers of observation to appreciate the scientific wonders that underlay everyday life.
Greenler was passionate about bringing science education to the broader community, but he was just as passionate about research within the university. He joined the UWM Physics Department in 1962 and was instrumental in developing the Laboratory for Surface Studies. During his tenure, he served in various positions for the Optical Society of America, the American Institute of Physics, and the Council of Scientific Society Presidents. He also authored several books, including Rainbows, Halos and Glories; Chasing the Rainbow: Recurrences in the Life of a Scientist, and Outside My Window: A Look at the Oakwood Village Nature Preserve.
He was recognized for his achievements with the Robert A. Millikan award, the UW-Milwaukee Ernest Spaights Plaza Award, and the Esther Hoffman Beller Award.
And, said Friedman, he was a genial colleague who cared for the people around him.
“He and his first wife Barbara entertained the entire Physics Department on their farm,” Friedman recalled. “There was a huge potluck, and after the meal, Bob would drive countless children around in a hay-wagon.”
Greenler accomplished a great deal during his distinguished career, but his greatest legacy will always be the students that he inspired – both those in his classrooms and those in the Milwaukee community.
By Sarah Vickery, College of Letters & Science