Discovering there's intelligent life beyond our planet could be the most transformative event in human history— but what if scientists decided to collectively ignore evidence suggesting it already happened?

That's the premise of a new book by a top astronomer, who argues that the simplest and best explanation for the highly unusual characteristics of an interstellar object that sped through our solar system in 2017 is that it was alien technology.

Sound kooky? Avi Loeb says the evidence holds otherwise, and is convinced his peers in the scientific community are so consumed by groupthink they're unwilling to wield Occam's razor.

Loeb's stellar credentials—he was the longest-serving chair of astronomy at Harvard, has published hundreds of pioneering papers, and has collaborated with greats like the late Stephen Hawking—make him difficult to dismiss outright.