The Download: digital twins, and where AI data really comes from

Steven Niederer, a biomedical engineer at the Alan Turing Institute and Imperial College London, has a cardboard box filled with 3D-printed hearts. Each of them is modeled on the real heart of a person with heart failure, but Niederer is more interested in creating detailed replicas of people's hearts using computers. These "digital twins" are the same size and shape as the real thing. They work in the same way. But they exist only virtually.