SCIENTIST AT WORK Rick Friedman for The New York Times Three paper shapes cut and pleated by Dr. Erik Demaine, who is applying insights from wrinkling and crinkling to questions in architecture, robotics and molecular biology. CAMBRIDGE, Mass. - "Some people don't even think this exists," says Dr. Erik Demaine, turning in his hands an elaborately folded paper structure. The intricately pleated sail-like form swooshes gracefully in a compound curve and certainly looks real enough - if decidedly tricky to make. Dr. Demaine, an assistant professor of computer science at the Massachusetts Institute of Technology, is the leading theoretician in...