Tyson begins the episode by explaining the nature of the speed of light and how much of what is seen of the observable universe is from light emanated from billions of years in the past. Tyson further explains how modern astronomy has used such analyzes via deep time to identify the Big Bang event and the age of the universe. Tyson proceeds to describe how the work of Isaac Newton, William Herschel, and James Clerk Maxwell contributed to understanding the nature of electromagnetic waves and gravitational force, and how this work led towards Albert Einstein's Theory of Relativity, that the speed of light is a fundamental constant of the universe and gravity can be seen as distortion of the fabric of space-time. Tyson describes the concept of dark stars as postulated by John Michell which are not visible but detectable by tracking other stars trapped within their gravity wells, an idea Herschel used to discover binary stars. Tyson then describes the nature of black holes, their enormous gravitational forces that can even capture light, and their discovery via X-ray sources such as Cygnus X-1. Tyson uses the Ship of Imagination to provide a postulate of the warping of spacetime and time dilation as one enters the event horizon of the black hole, and the possibility that these may lead to other points within our universe or others, or even time travel. Tyson ends on noting that Herschel's son, John would be inspired by his father to continue to document the known stars as well as contributions towards photography that play on the same nature of deep time used by astronomers.

Andrew Graham-Dixon examines early Christian art and the reasons for its evolution during the Renaissance. He also reveals just how far modern artists have been influenced by the pre-perspective view of the world.

There is a tendency to deny German culture the equal reverence of Italy or Spain, and this enlightening new series provides a wonderful opportunity to explore a great, yet often neglected, artistic tradition whose influence has been just as profound. Andrew Graham-Dixon concludes his exploration of German art by investigating the dark and difficult times of the 20th century. Dominating the landscape is the figure of Adolf Hitler, failed artist, would-be architect and obsessed with the aesthetics of his 1,000-year Reich". In a series of extraordinary building projects and exhibitions, Hitler waged a propaganda war against every form of modern art as a prelude to unleashing total war on the whole of Europe. After the war the shadow of the Third Reich persisted, Germany remained divided and traumatised. How would artists deal with a past that everybody wanted to forget? Journeying through the work of Otto Dix and George Grosz and the age of the Bauhaus to the post-war painters Georg Baselitz, Hilla Becher and the conceptual artist Joseph Beuys is a long and strange journey, but the signs that art has a place at the heart of the new reunited Germany are clearly visible.

What was the Wehrmacht? A group of obedient yeasayers? A murdering band of thugs? An army of millions of abused young men? This series in 5 parts provides differentiated and conclusive answers based on the latest historical and comprehensive investigative research, bringing many new facts to light – among them documents proving for the first time ever, what many among the officers actually thought. Blitzkrieg, the lightning war, in German incorporate modern weapons and vehicles as a method to help avoid the stalemate of trench warfare and linear warfare in future conflicts. The first practical implementations of these concepts coupled with modern technology were instituted by the Wehrmacht in the opening theatres of World War II. The strategy was particularly effective to Germany in the invasions of Western Europe and initial operations in the Soviet Union. These operations were dependent on surprise penetrations, general enemy unpreparedness and an inability to react swiftly enough to German offensive operations.

The series is a re-examination of some of the under-reported and darkest parts of American modern history using little known documents and newly uncovered archival material, looking beyond official versions of events to the deeper causes and implications and exploring how events from the past still have resonant themes for the present day. This episode addresses the historical backround, consequences and reasons behind the use of atomic bombs against the Japanese in the second world war.

One and a half million years ago, a new breed of ape-man walks the land. In southern Africa, Homo Ergaster has taken the next step to becoming human. They have long, modern looking noses, which cool air as they breathe. Their hairless bodies, with millions of tiny sweat glands, mean they don't pant anymore to control their temperature - they sweat. And, above all, they have big brains - nearly two-thirds the size of ours.