“Amazon engineer Greg Linden originally introduced doppelganger searches to predict readers’ book preferences, the improvement in recommendations was so good that Amazon founder Jeff Bezos got to his knees and shouted, “I’m not worthy!” to Linden. But what is really interesting about doppelganger searches, considering their power, is not how they’re commonly being used now. It is how frequently they are not used. There are major areas of life that could be vastly improved by the kind of personalization these searches allow.”