Paul J. Nahin is professor emeritus of electrical engineering at the University of New Hampshire. He is the author of 21 books on mathematics, physics, and the history of science, published by Springer, and the university presses of Princeton and Johns Hopkins. He received the 2017 Chandler Davis Prize for Excellence in Expository Writing in Mathematics (for his paper "The Mysterious Mr. Graham," The Mathematical Intelligencer, Spring 2016). He gave the invited 2011 Sampson Lectures in Mathematics at Bates College, Lewiston, Maine.