Not long after he arrived on the Stanford University campus in 2022 as a 17-year-old freshman, Theo Baker received a tip about the school’s president, the neuroscientist Marc Tessier-Lavigne. Baker, the son of two prominent Washington, D.C., journalists, had joined the staff of The Stanford Daily and was looking for a story he could dig into. And here it was: On a website called PubPeer, a forum for discussing scientific papers, critics were claiming that papers coming out of Tessier-Lavigne’s lab contained manipulated and fraudulent data. And that it had been going on for years.