Last month, theoretical physicist Avi Loeb made headlines with the sensational claim that tiny spherules recovered from the bottom of the ocean were probably of alien origin. “It’s most likely a technological gadget with artificial intelligence,” he said to The New York Times, which published a story today about the Harvard professor’s contentious claims. Although the biggest scientific breakthroughs often start with a bold hypothesis, Loeb’s peers believe the decorated astrophysicist’s assertions can be called many things — but “good science” isn’t one of them.