For the last half-century or so, astronomers around the world have been scanning the cosmos with massive radio telescopes in hopes of finding some sign of intelligent life. This network of alien-hunters comprises the Search for Extraterrestrial Intelligence (SETI), but despite all their efforts, the interstellar radio waves have remained quiet. One might even say too quiet.

Depending on who you ask, first contact with an extraterrestrial civilization might happen any day now. Seth Shostak, director of the SETI Institute, has famously predicted that we’ll hear from ET within the next two decades. Others, such as the Cornell University astronomer Yervant Terzian are less optimistic — his probabilistic calculations place first contact in about 1,500 years, assuming there’s anyone left on Earth to receive the call. READ MORE