What we’ll learn from the long process of decommissioning the pioneering JET reactor. Plus, China’s new dark matter lab is the biggest and deepest yet, and the debate over whether megalodon was stocky or slim. What we’ll learn from the long process of decommissioning the pioneering JET reactor. Plus, China’s new dark matter lab is the biggest and deepest yet, and the debate over whether megalodon was stocky or slim.