Traveling is supposed to open your mind and expand your horizons — but what if it doesn't? In her new book Airplane Mode, author Shahnaz Habib suggests that sometimes, traveling does more to enforce our ideas about the world than to upend them. Which means that people with "passport privilege" — AKA, the ability to travel freely from country to country — may end up feeling like the stars of some massive international adventure, while people whose travel is more restricted feel like perpetual interlopers.