>>> welcome to amanpour on pbs. tonight, 50 years after martin luther king jr.'s assassination, whill itake to rekindle the dream? isk william a former obama official who helped mentor an initiative for young black men and civil rights activist who is in memphis joining the 50th anniversary commemoration there. plus, we talked with the publisher of dr. king's paper, trayvon carson, he joins us from stanford. ♪ ♪ >>> "amanpour on pbs" was made possible by the generous support of rosalynn p. walter. >>> good evening, earn, and welcome to the program. i'm christiane amanpour in london. 50 years ago on the balcony of the lorraine motel in memphis, a man who had dedicated an entire life to non-violent protest was