For more than 60 years, scientists have been pointing radio antennas at the sky, hoping to overhear a broadcast from an alien civilization—proof that we’re not alone in the universe.
But the search for extraterrestrial intelligence, or SETI, is like listening for a whisper in a hurricane. Space is incomprehensibly big. There’s noise sputtering from every direction, especially from the countless number of stars dying and being born. A signal from E.T. might be faint. We’ve got only so many instruments and so much time, money and manpower for our intergalactic eavesdropping.
Worse, we might not even recognize an alien broadcast when we hear it. After all, who knows how E.T. would actually communicate?