Some exobiologists believe that if there were any other civilizations in the universe, they would probably be much older than ours and would thus have knowledge of radio signals and use them to contact earth.
Beberapa eksobiolog percaya bahwa seandainya ada peradaban lain di jagat raya, kemungkinan besar peradaban mereka jauh lebih tua daripada peradaban kita dan, dengan demikian, memiliki pengetahuan tentang sinyal radio serta menggunakannya untuk menghubungi bumi.