 The Jewish population's "Jewish geography," therefore, is what makes the game possible and lets Jews from different cities, regions, and countries easily discover people they know in common.Both the game and the concept are Jewish-specific examples of the six degrees of separation theory proposed by Hungarian writer Frigyes Karinthy in 1929 and the small world phenomenon hypothesized by social scientist Stanley Milgram in 1967.While the accuracy of these theories have been questioned by some, few Jews doubt the validity of "Jewish geography," having observed its connective power firsthand.