Zeynep Tufekci from ted.comToday, a single email can launch a worldwide movement. But as sociologist Zeynep Tufekci suggests, even though online activism is easy to grow, it often doesn't last. Why? She compares modern movements -- Gezi, Ukraine, Hong Kong -- to the civil rights movement of the 1960s, and uncovers a surprising benefit of organizing protest movements the way it happened before Twitter.