The history of radio astronomy has been a series of discoveries, mostly serendipitous, using a new instrument, or using an old instrument in a new unintended way. Theoretical predictions have had little influence, and in some cases actually delayed the discovery by discouraging observers. Many of the key transformational discoveries were made while investigating other areas of astronomy; others came as a result of commercial and military pursuits unrelated to astronomy. We discuss how the transformational serendipitous discoveries in radio astronomy depended on luck, age, education, and the institutional affiliation of the scientists involved, and we comment on the effect of peer review in the selection of research grants, observing time, and the funding of new telescopes, and speculate on its constraint to new discoveries. We discuss the decrease in the rate of new discoveries since the Golden Years of the 1960s and 1970s and the evolution of radio astronomy to a big science user oriented discipline. We conclude with a discussion of the impact of computers in radio astronomy and speculations on the potential for future discoveries in radio astronomy – the unknown unknowns.