Won the Nobel Prize in Physics in 1960 for inventing, at 25, an ingenious device called the bubble chamber to trace the paths of subatomic particles. In creating the chamber, Dr. Glaser — a restless scientist who later turned to microbiology and developing cancer therapies — proved his most renowned skeptic, Enrico Fermi, a giant of 20th-century physics, wrong. Dr. Glaser, who was teaching at the University of Michigan at the time, was fortunate that he did not know that Fermi had calculated that a bubble chamber would never work. Only afterward, after Fermi had invited Dr. Glaser to the University of Chicago to give a talk about the bubble chamber, did Dr. Glaser look up Fermi’s calculation in a thermodynamics textbook. There he found an erroneous equation. Donald Arthur Glaser was born on Sept. 21, 1926, in Cleveland, to William J. Glaser, a businessman, and his wife, Lena. After attending public schools, he received a bachelor’s degree in physics and mathematics in 1946 from the Case School of Applied Science, which later became part of Case Western Reserve University. He earned a doctorate from the California Institute of Technology. He joined the faculty at Michigan in 1949 and invented the bubble chamber in 1952, before his 26th birthday. Dr. Glaser moved from Michigan to the University of California, Berkeley, in 1959. He was 34 when he won the Nobel, in 1960. Dr. Glaser’s first marriage, to Ruth Bonnie Thompson, ended in divorce. In addition to his wife, the former Lynn Bercovitz, he is survived by a daughter, Louise, and a son, William, both from his first marriage, and four grandchildren.