Michio Kaku (lev radin / Shutterstock.com) In late February, retired Air Force Major General Neil McCasland stepped out for a walk from his New Mexico home and didn't return. His wife has said he'd been struggling with brain fog and physical decline and had told her more than once that he "didn't want to live like that." Social media had other ideas. He'd run a "UFO-linked" lab, they said. He knew "America's deepest, darkest secrets." Daniel Engber at The Atlantic calls the missing-scientists panic a "sham in every way at once" . The people on the list aren't all scientists, aren't all in the same field, and didn't die or disappear in any kind of cluster. Other names piled on, and the list quickly stopped making sense. Melissa Casias, a Los Alamos employee who went missing last year, was an administrative assistant, not a scientist. Jason Thomas was a chemical biologist at Novartis, working on drug discovery.…