For decades after the disaster, there was little doubt about what sank the Titanic. When the "unsinkable" ship, the largest, most luxurious ocean liner of its time, crashed into an iceberg on its maiden voyage in 1912, it took more than 1,500 of its 2,200 passengers to the bottom. As the ship slipped into the North Atlantic, so, too, did the secret of how and why it sank....

In two new books, a group of historians, naval architects, and materials scientists argue that fresh evidence has further unraveled the familiar story of the Titanic, raising more questions about what caused the disaster. In What Really Sank the Titanic: New Forensic Discoveries, Jennifer Hooper McCarty, a materials scientist at Oregon Health and Science University, and Tim Foecke, a scientist at the National Institute of Standards and Technology, make the case that it wasn't the ship's steel that was weak; it was the rivets, the all-important metal pins that held the steel hull plates together. Titanic's Last Secrets, to be published next month, describes the work of Richie Kohler and John Chatterton, wreck-diving historians who believe two recently discovered pieces of the Titanic's bottom prove the ship's stern never rose high in the air the way many Titanic experts, including Cameron, originally believed. The two divers, whose discovery of a lost German U-boat was chronicled in the book Shadow Divers, say the ship broke up and sank while still relatively flat on the surface—a potential sign of weakness, they believe, that was covered up after the disaster.