Katty Kay in Washington and Christian Fraser in London return to report on the events that are shaping the world.

Christmas-themed quiz for university alumni. Two teams return to compete in the last semi-final. Show more

How Albert Einstein thought he had found the fatal flaw in quantum theory, because it implies that sub-atomic particles can communicate faster than light. Show more

Documentary which follows the construction of a trailblazing 36,000-tonne steel structure to entomb the ruins of the nuclear power plant destroyed in the 1986 Chernobyl disaster. Show more

Michael Mosley investigates Porton Down, Britain's most secretive and controversial military research base. He comes face to face with chemical and biological weapons old and new. Show more

A Storyville documentary: how the Slovenian cult band Laibach became the first rock group ever invited to perform in the dictatorially repressed state of North Korea. Show more

Dan Snow presents a series on the Royal Navy's role in British history. Dan looks at the evolution of Nelson's navy and the national enterprise which supported it. Show more

Antonio Pappano explores the great roles and singers through the prism of the main voice types. He concludes by looking at the baritones and basses. Show more

Documentary which follows the construction of a trailblazing 36,000-tonne steel structure to entomb the ruins of the nuclear power plant destroyed in the 1986 Chernobyl disaster. Show more

Jim Moir aka Vic Reeves goes on an irreverent trip into the world of influential avant-garde art movement Dada. Show more