(FORTUNE Magazine) – What do you do for an encore after winning a Nobel Prize? Mel Schwartz, 56, a former Columbia University professor who won the physics honor last fall, is hoping for similar accolades in business. His company, Digital Pathways of Mountain View, California, is about to introduce a high-tech security system designed to protect data networks from computer viruses. At Columbia, Schwartz helped build the first device to detect the mysterious subatomic particle called the neutrino. But several years after doing the research that would eventually win him the Nobel, he became bored with high- energy physics. ''Your imagination goes and you begin to think like everyone else,'' Schwartz says. In 1970 he began Digital Pathways, which was initially a consulting firm. By the late 1970s the small, private company had found its niche as a supplier of security systems for corporations' computer networks. Now Digital Pathways is testing a system that could protect users against computer viruses. Once a virus gets into a computer network, it inexorably spreads to sensitive files and terminals, erasing or altering data as it moves along. By limiting a user's access to certain files, the Digital Pathways security system creates ''bulkheads'' that prevent the virus from spreading. The former professor says he made many mistakes in his transition from classroom to boardroom. He once spent several months working on a product for a small medical company, then discovered it had no money to pay him. The Nobel Prize, which came 26 years after Schwartz did his research, has not changed life at Digital Pathways. Such awards do a lot for the ego but not much for the balance sheet.