With the rapid emergence of digital devices, an unstoppable, invisible force is changing human lives: Big Data, a word that was barely used a few years ago but now governs the day for many of us. The real time visualization of data streaming in from satellites, billions of sensors and GPS enabled cameras and smart phones is beginning to enable us to sense, measure and understand aspects of our existence in ways never possible before". This massive gathering and analysing of data in real time is also allowing us to address to some of humanity biggest challenges, including pollution, world hunger and illness, and it is also helping create a new kind of planetary nervous system. But as Edward Snowden and the release of the NSA documents have shown, the accessibility of all this data comes at a steep price. The Human Face of Big Data captures the promise and peril of this extraordinary knowledge revolution.

Memory is the glue that binds our mental lives. Without it, we’d be prisoners of the present, unable to use the lessons of the past to change our future. From our first kiss to where we put our keys, memory represents who we are and how we learn and navigate the world. But how does it work? Neuroscientists using cutting-edge techniques are exploring the precise molecular mechanisms of memory". By studying a range of individuals ranging —from an 11-year-old whiz-kid who remembers every detail of his life to a woman who had memories implanted— scientists have uncovered a provocative idea. For much of human history, memory has been seen as a tape recorder that faithfully registers information and replays intact. But now, researchers are discovering that memory is far more malleable, always being written and rewritten, not just by us but by others. We are discovering the precise mechanisms that can explain and even control our memories. The question is— are we ready?

Citizenfour received the Academy Award for Best Documentary Feature at the 2015 Oscars. The film was directed by Laura Poitras concerning Edward Snowden and the NSA spying scandal." In January 2013, Laura Poitras received an encrypted e-mail from a stranger who called himself Citizen Four. In it, he offered her inside information about illegal wiretapping practices of the NSA and other intelligence agencies. Poitras had already been working for several years on a film about monitoring programs in the US, the result of the September 11 attacks. In June 2013, accompanied by investigative journalist Glenn Greenwald and The Guardian intelligence reporter Ewen MacAskill, she went to Hong Kong with her camera for the first meeting with the stranger, who identified himself as Edward Snowden. Several other meetings followed. The recordings gained from the meetings form the basis of the film.

Evolution tells us that all life exists for only one purpose: to reproduce. But is that all there is? How could such a simple imperative lead us to create great art and civilizations? A new theory suggests that instead of passing on genes, our ultimate purpose is to process and pass on information. We are the universe figuring itself out. Scientists dig deep into DNA, chemistry, technology and engineering to find the meaning of life. One thing is certain: living is easier if you find a reason for living.

In the last of the series, Julian Richards uncovers new information from the battle in 1066 between Viking warlord Harald Hardrada and King Harold of England that marked the end of the Viking age in Britain. Results from a nationwide genetic survey show where in Britain the Vikings left a measurable contribution.

Professor Brian Cox travels from the fossils of the Burgess Shale to the sands of the oldest desert in the world to show how light holds the key to our understanding of the whole universe, including our own deepest origins. To understand how light holds the key to the story of the universe; you first have to understand its peculiar properties. Brian considers how the properties of light that lend colour to desert sands and the spectrum of a rainbow can lead to profound insights into the history and evolution of our universe. Finally, with some of the world's most fascinating fossils in hand, Brian considers how but for an apparently obscure moment in the early evolutionary history of life, all the secrets of light may have remained hidden. Because although the universe is bathed in light that carries extraordinary amounts of information about where we come from, it would have remained invisible without a crucial evolutionary development that allowed us to see. Only because of that development can we now observe, capture and contemplate the incredible wonders of the universe that we inhabit.