Mobile payments are happening to the retail industry like bankruptcy happens to Mike Campbell in Ernest Hemingway’s The Sun Also Rises: gradually, and then suddenly all at once. Google has offered mobile payments for three years, and Walmart and Best Buy have been talking about mobile pay since 2012. But Apple is one of the few companies that many observers say can quickly lead a critical mass of people to wave their phones in the air for everything from bed sheets to burgers. Retailers, credit card companies and banks all have made big bets on Apple’s new mobile payment system, which makes it more likely to succeed.