At age 75, the legendary singer-songwriter, who won fame during the protest movements of the Sixties, still performs. His extraordinary career has been chronicled in films, books, and dozens of record albums.
At Harvard since 1993, Oliver Hart has argued that the incentives for cost reductions in privatized services, such as private prisons in the United States, are typically too strong.
See the Nobel Prize winner leave Jon Stewart speechless.
Yousafzai is the youngest winner in the history of the prestigious prize.
Here's what you need to know about this year's winner.