Kenneth I. Greisen, Prof. of Physics Emeritus and former Dean of the Faculty at Cornell, died on March 17, 2007 at age 89, at the Hospicare of Ithaca residence.
Prof. Greisen was born in Perth Amboy, NJ, on January 24, 1918, to Signa and Invard Greisen. He attended Wagner College from 1934-35. After graduating with a BS from Franklin & Marshall College in 1938, he came to Cornell University for graduate work in physics, completing his Ph.D. in 1942, working with Bruno Rossi. The remainder of his career was based at Cornell, except for participation in the Manhattan Project at Los Alamos, NM from 1943 to 1946. There he was a member of a team of physicists and engineers whose efforts led to the history-changing "Trinity" atomic bomb test of July 16, 1945. As an observer of that test, his commentary has become an important historical record of that event. Later he was also to sign, along with Hans Bethe and other scientists, a letter to the President strongly advocating only non-military use of nuclear research.
He returned to Cornell in 1946, thus beginning a long and distinguished academic career as research physicist, physics teacher and University leader, prior to his move to Emeritus status in 1984. His physics research centered in a deep and extended study of cosmic rays, the high energy particles and radiation received at the Earth from outer space. In the 1960's, he and his students and research associates installed an array of cosmic ray detectors on the hills around Ithaca to study the large showers of particles which are initiated by incoming, high energy particles. This work was a progenitor of a project dubbed "Fly's Eye" at the University of Utah, and a current, large-scale international project located in the Andes Mountains in Argentina.
His contributions to the study of cosmic rays continue to influence the field. In 1966 Greisen had predicted that cosmic rays from distant sources could not reach the Earth if their energy were above a certain limit. Instead, they would lose their excess energy by interacting with the microwave background radiation which fills all of space. Two Russian scientists, Kuzmin and Zatsepin, made the same prediction independently, and the proposed limit became known as the "GZK Limit." Although some recent experiments have suggested there may be cosmic rays that violate the GZK limit, the most recent and accurate observations, made in Utah using a method designed by Prof. Greisen, appear to have seen the effect predicted by Ken at the energy predicted by him.
In 1970, Greisen helped found the High Energy Astrophysics Division of the American Astronomical Society, and served as its first Chair. In 1974 he was elected to membership in the National Academy of Sciences. From 1976 to 1979 he served as Chair of Cornell's Department of Astronomy.
Greisen was also a strong participant in efforts to improve the effectiveness of physics education. Along with Philip Morrison and Hans Bethe from Cornell, he participated in the work of the Physical Science Study Committee in the late 1950's. Their work, based at the Massachusetts Institute of Technology, instigated a major review of the content of high school science courses in the U.S. In addition to a period of years as chair of the physics faculty major advisors group, he served as faculty leader for the redesign of several introductory physics courses at Cornell.
His service to the wider Cornell University community included serving as University Ombudsman from 1975 to 1977, and culminated in his leadership as Dean of the University Faculty from 1978 to 1983.
He also contributed to the Ithaca community, primarily through income tax counseling and driving for FISH and Gadabout, but also in helping with Meals on Wheels, the Senior Center board, and other activities.
Ken loved both choral singing and instrumental music, and was a frequent attendee at area concerts. He was a long-time member of the Unitarian church choir, and later the Presbyterian choir and the Senior Chorus. He loved playing the flute and the recorder, and also enjoyed hand bell ringing. He enjoyed outdoor activities of many kinds, including bicycling and canoeing (even briefly trying roller blading well after retirement). He had a long-standing love of the Adirondacks, from college days as a guide at a camp, to numerous family vacations over the years, and finally to owning a summer camp on Piseco Lake for some 15 years. The Maine sea shore was a favorite as well, and he also enjoyed winter vacations with family and friends, over a number of years, first in Kauai and later Florida.
Ken was preceded in death by first wife Elizabeth (of 34 years); second wife Helen (of 20 years); sister Agnita Dupree; brother Sigurd Greisen; and stepson Bruce Wiltberger. Ken is survived by children Eric Greisen of New Mexico and Kay Greisen of Ohio; stepchildren Heather Wiltberger of Virginia, Paul Wiltberger of Washington state, and Lois Wiltberger of Massachusetts; various nieces and nephews; and their spouses and children.
A memorial service will be held in the Kendal Auditorium on April 22, 2007 at 3:00 p.m., with a reception to follow. In lieu of flowers, Ken requested that donations be made to Hospicare or to Kendal.