Philip Morrison was a professor of physics at the Massachusetts Institute of Technology (MIT). He is known for his work on the Manhattan Project during World War II, and for his later work in quantum physics, nuclear physics, high energy astrophysics, and SETI.

Giuseppe Cocconi (1914–2008) was an Italian physicist who was director of the Proton Synchrotron at CERN in Geneva. He is known for his work in particle physics and for his involvement with SETI where he wrote, "[t]he probability of success is difficult to estimate; but if we never search, the chance of success is zero."