The search for intelligence beyond Earth has long entranced humans. According to Jon Gertner, a regular contributor to The New York Times Magazine, this search has been defined “by an assumption that extraterrestrials would have developed radio technologies akin to what humans have created.” However, Mr. Gertner writes, “rather than looking for direct calls to Earth, telescopes now sweep the sky, searching billions of frequencies simultaneously, for electronic signals whose origins can’t be explained by celestial phenomena.” What scientists are most excited about is the prospect of other planets’ civilizations being able to create the same “telltale chemical and electromagnetic signs,” or, as they are now called, “technosignatures.”