It all started when Nathan Allen was stuck in the lab, babysitting his experiments for hours at a time. The 10- or 15-minute blocks between checking on his reactions weren’t long enough to dig into anything substantial. Instead, he recalls, “I posted snarky comments on the internet, which you can do in five minutes.” Soon, Allen was answering science questions on the website Reddit, where he saw people being led astray by bad science. Now Allen, 42, is one of the most powerful science communicators in the U.S. as head moderator of Reddit’s science community, called the science subreddit (www.reddit.com/r/science). The science subreddit has almost 18 million subscribers and is growing by the equivalent of the Chicago Tribune’s print circulation—about 500,000—every month. By day, Allen is a synthetic organic chemist at MilliporeSigma in Milwaukee, where he lives with his wife and two daughters, two and five years old. Leading the