Today, our rovers are digging ever deeper for fossils in Martian rock, and our telescopes are spying ever more closely for organic breath in Venusian air. There’s the sense that we’re just now coming to terms with the idea that there really might be life beyond our little blue marble. But that perspective had actually once been widespread.
“For a long period of time the assumption was that all planets must be inhabited. ‘It would be crazy if they weren’t,’ people thought,” said Anders Sandberg , of the University of Oxford’s Future of Humanities Institute, in an interview. “As people started doing better astronomical observations, they started going back and forth. People decided maybe we're alone in the universe.”
Over the last decade, scientific thinking on the topic has become increasingly optimistic. In 2014, results from the Kepler Space Telescope showed that Earth-sized planets around other stars are likely common. Intelligent life might therefore also be common. A number of researchers are currently searching for this life in what has come to be formally described in academic circles as the search for extraterrestrial intelligence, or SETI.