Ralph Belknap Baldwin was born in Grand Rapids June 6, 1912 to Julie Belknap (a descendant of Captain Charles E. Belknap) and Melvin D. Baldwin. Ralph graduated from Central High School in 1930 and earned undergraduate and graduate degrees from the University of Michigan (B.S, 1934; M.S., 1935; Ph.D. 1937; and LL.D., 1975).

With his specialization in astrophysics, from 1935 through 1942 he taught astronomy successively at the University of Michigan, University of Pennsylvania, and Northwestern University. After marrying Lois Virginia Johnston on August 3, 1940 (children: M. Dana II, Pamela and Bruce), Baldwin was asked to join the Applied Physics Laboratory (APL) in 1942 as a senior physicist, where he was assigned the task of developing the proximity fuse, a weapon that proved instrumental during the last months of World War II. The importance of the fuse is described in his 1980 book, The Deadly Fuse: The Secret Weapon of World War II. Baldwin also wrote several books dealing with astrophysics: The Face of the Moon in 1949, The Measure of the Moon in 1963 and The Moon: A Fundamental Survey in 1965.

In addition to his career in science, Baldwin began working for the family-owned Oliver Machinery Company in Grand Rapids in 1947 as production manager. After a series of other jobs with the firm, he was made president in 1970 and chairman of the board in 1982. He retired in 1984 and is currently spending winters in Naples, Florida and summers in Grand, Rapids Michigan.