This article describes how professors became magnets for crackpots bearing pet theories and searching for validation. Scott A. Hughes, an associate professor of physics at the Massachusetts Institute of Technology, received a 22-page, single-spaced screed this May just begging for a place in the crackpot file. The subject line read, in part, "God's language is CRYPTOGRAPHY which reveals that Global Warming is the end of the world." That message also went to 33 other physicists at MIT, Harvard, and Princeton. Mr. Hughes is in good company when it comes to attracting attention from would-be geniuses. According to researchers, fields as diverse as archaeology, literature, and mathematics each nurture a different type of crank. Most often, the obsessed attention seekers are harmless, even when they accost professors at meetings or wander the halls of a department looking for an open door. Some reach beyond private inquiries to post bile-filled messages about a scholar's work on Internet discussion groups. And one professor who studied cranks was even sued by an irate correspondent, who later came knocking on his front door.