Trillions of dollars in payments each year occur via mobile apps like Alipay in China, where the cashless society of the future is here. You can even pay for your fried chicken with facial recognition technology. We’re eschewing conventional finance rules in the U.S., too, or at least Chelsea Fagan is. She talks to Adrienne Hill about her new book, “The Financial Diet,” which offers personal finance advice a little differently than we’re used to. Plus, a look back at the year’s energy news, how one lab researching serious infectious diseases is expanding to keep up with the increasing rate of outbreaks, and a first-hand account of the invention of the digital camera.