It’s hard to say that Thomas Heldt has had just one career. He’s assisted with open heart surgery. He’s studied the physiology of human space travel. Most recently, he’s designed medical devices to help patients with brain injury. “It’s been a serendipitous path,” says Heldt, a recently tenured faculty member in MIT’s Department of Electrical Engineering and Computer Science (EECS). But there is a through line: Heldt operates at the intersection of physics and medicine, where fundamental physical principles intersect with human health. And through his varied career, Heldt has…