We move around in space, but we are stuck in a prison of time moving ever forwards. Einstein said, 'The distinction between past, present and future is only a stubbornly persistent illusion.' Is our experience of the ticking clock merely a trick of the mind? Could science ever make the clock move backwards? Experiments in quantum physics are showing that the future influences the present: what happens later limits the choices we think we have now. The laws of physics say visiting or talking to ourselves in the past is possible – but changing history once we get there is not.

The BBC's definitive television history of the rise and fall of the Nazis. The Nazis - A Warning From History exposes the popular myths surrounding the rise and fall of the Third Reich. The series explores how the Nazis came to power, how they ruled, how they treated their occupied territories and, above all, how a cultured nation could be responsible for such acts of inhumanity. How could a political party as fundamentally evil and overtly racist as the Nazis come to power? This remains one of the most enigmatic questions of the last century. Acclaimed historian Laurence Rees examines what led a cultured nation at the heart of Europe to commit the atrocities it did. In so doing, he exposes popular myths and encourages understanding of the real forces that led to one of the darkest chapters in modern history. Was it simply the hypnotic power of Hitler's rhetoric? Did the Gestapo really impose themselves by terror on an unwilling population? Through interviews with witnesses and perpetrators, along with archive film and records, this six-part series unveils a more chilling reality.

In this episode he traces India in the days of the Roman Empire. In Kerala the spice trade opened India to the world, whilst gold and silk bazaars in the ancient city of Madurai were a delight for visiting Greek traders. From the deserts of Turkmenistan Michael travels down the Khyber Pass to Pakistan to discover a forgotten Indian Empire that opened up the Silk Route and at Peshawar built a lost Wonder of the World.

Dr Michael Mosley seeks to establish the truth about meat. Every year, humans raise and eat 65 billion animals - nine animals for every person on the globe. In this eye-opening documentary, Michael examines the impact that this is having on the planet and finds out what meat eco-friendly carnivores should be buying. Is it better to buy free-range organic or factory-farmed meat? The answers are far from obvious.

Investigative journalist Jeremy Scahill travels to Afghanistan, Yemen, Somalia, and other countries where the United States has taken military action in the War on Terror. In Afghanistan, he investigates the United States military and government cover-up of the deaths of five civilians, including two pregnant women killed by US soldiers from the Joint Special Operations Command. After investigating the attack, Scahill travels to other sites of JSOC intervention, interviewing both proponents and opponents, and the survivors, of such raids,including U.S. Senator Ron Wyden. Scahill also investigates the assassinations of American citizens Anwar al-Awlaki and his son Abdulrahman al-Awlaki, meeting with their family at their home in Yemen. Scahill suggests that the War on Terror is in fact a "self-fulfilling prophecy" and causes the radicalization of Muslims. He also discusses the case of Yemeni investigative journalist Abdulelah Haider Shaye who was detained, tried and sentenced on terrorism-related charges after reporting on American drone strikes.

Montezuma Dan Snow journeys to the ancient heart of Mexico in search of the lost civilisation of the Aztecs and their last and greatest ruler, Montezuma II (1502-1520). Montezuma inherited an empire of five million people, stretching from present-day Mexico to Nicaragua, from his uncle. His rule was marked by incessant warfare. Enemy states were growing more powerful and conquered tribes were becoming more rebellious. Within months of taking the throne in 1502, he went changed a man of good reason into a pitiless autocrat who declared himself a god, believing that fear and ruthlessness were the only ways to stop the empire falling apart. Yet it was at the hands of Cortes and the Spanish conquistadors that Montezuma met his downfall. But what was his relationship with Cortes, and why did such a ruthless leader submit to his captors with such relative ease? As Dan Snow visits the ruins and picks through current excavations, he pieces together the evidence of a gripping story: a divine tragedy of errors, the clash of civilisations, the end of a world - and a very human God.