Otto Struve, (1897 - 1963) was one of the few eminent astronomers in the pre-Space Age era to publicly express a belief that extraterrestrial intelligence was abundant, and so was an early advocate of the search for extraterrestrial life. Otto Struve completed his Ph.D. dissertation in 1923 and became director of Yerkes Observatory at the University of Chicago. He subsequently directed four different observatories in all, in addition to serving as editor of the Astrophysical Journal and authoring numerous books. Struve was also president of the International Astronomical Union.
George Wells Beadle (October 22, 1903 – June 9, 1989) was an American scientist in the field of genetics, and Nobel Prize in Physiology or Medicine Nobel laureate who with Edward Lawrie Tatum discovered the role of genes in regulating biochemical events within cells.
Niels Bohr (1885 - 1962) was a Danish physicist who made critical contributions to the understanding of atomic structure and quantum mechanics. He was a professor at the University of Copenhagen, and founded and directed the Institute of Theoretical Physics in 1921. He was awarded the Nobel Prize in physics in 1922, and subsequently collaborated with several world-renowned scientists throughout his career, including Albert Einstein and Albert and Marie Curie. In 1941, Bohr was recruited to work at the top-secret Los Alamos Laboratory in New Mexico on the Manhattan Project, and became a long-time advocate of scientific openness and the peaceful use of nuclear energy. Bohr is considered to be one of the most influential scientists of the 20th century.