Electricity is not just something that creates heat and light, it connects the world through networks and broadcasting. After centuries of man's experiments with electricity, the final episode tells the story of how a new age of real understanding dawned - how we discovered electric fields and electromagnetic waves. Today we can hardly imagine life without electricity - it defines our era. As our understanding of it has increased so has our reliance upon it, and today we are on the brink of a new breakthrough, because if we can understand the secret of electrical superconductivity, we could once again transform the world.

Since 2010, Artificial Intelligence is revolutionized by deep learning, neural networks that discern complex patterns in huge quantities of data and react in real time. A.I. is a primal force, like fire. The same fire that warms us can incinerate our homes; A.I. could enslave mankind -- or, join us in a grand alliance to reach the stars.

Diarmaid MacCulloch's own life story makes him a symbol of a distinctive feature about Western Christianity - scepticism, a tendency to doubt which has transformed both Western culture and Christianity. In the final programme in the series, he asks where that change came from. He challenges the simplistic notion that faith in Christianity has steadily ebbed away before the relentless advance of science, reason and progress, and shows instead how the tide of faith perversely flows back in. Despite the attacks of Newton, Voltaire, the French Revolutionaries and Darwin, Christianity has shown a remarkable resilience. The greatest damage to Christianity was actually inflicted to its moral credibility by the two great wars of the 20th century and by its entanglement with Fascism and Nazism. And yet it is during crisis that the Church has rediscovered deep and enduring truths about itself, which may even be a clue to its future.

Take a look back at many of the most fascinating science stories of 2017, a year full of stunning advancements in individual fields of study, from astronomy to biology, geology to history – when we piece these discoveries together we see the year in a new light.

Scientists investigate the way the Sun builds its power -- through fusion -- hoping to find a way to use fusion as a less dangerous and less radioactive waste-producing path to energy than fission. But there are some major difficulties along the way. Fusion really is the perfect way to make energy. We have millions of years worth of fuel. It produces no long-lived radioactive waste. If we can solve the engineering challenges, energy will become cheaper, more available for everybody.

A new age of space exploration is dawning. But surprisingly, some of the boldest efforts at putting humans into space are now those of private companies started by a handful of maverick billionaire businessmen. In this film, Brian Cox gains exclusive access behind the scenes at Virgin Galactic, Blue Origin and Spaceport America, exploring what is really happening in privately financed space flight right now.