What if we could travel not just through space, but through time itself? If you could travel through time, would you change the past or the future? What if you found it couldn’t be changed? What price does the time traveller -- and the people they are closest to -- pay? This is a journey from H. G. Wells' The Time Machine through ideas like The Grandfather Paradox and The Butterfly Effect to the professional time traveller that is the ever popular Doctor Who. Steven Moffat, David Tennant, Karen Gillan, and Neil Gaiman offer a unique perspective on the Doctor. Edward James Olmos reveals the hidden meaning of the language he created for the vision of the future that is Blade Runner. Bob Gale and Christopher Lloyd take us behind the scenes of Back to the Future, while Ed Solomon describes the joy of solving a time travel conundrum for Bill & Ted’s Excellent Adventure. But what would be the physical and emotional cost to the time traveller? Audrey Niffenegger explains what inspired her novel The Time Traveller’s Wife. And what if someone from the future tried to travel back in time to warn us? Would we believe them? From the apocalyptic tones of 12 Monkeys to the drama of Quantum Leap and the comedy of Groundhog Day, time travel is a subject that has been irresistible to the creators of every type of science fiction.

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.

Discover the story behind the scenes of the band's fifth studio album Hotel California, one of the best-selling albums of all time. Henley said about this work: 'They are the same themes that run through all of our work: loss of innocence, the cost of naiveté, the perils of fame, of excess; exploration of the dark underbelly of the American dream, idealism realized and idealism thwarted, illusion versus reality, the difficulties of balancing loving relationships and work, trying to square the conflicting relationship between business and art; the corruption in politics, the fading away of the Sixties dream of peace, love and understanding.

Fights within Eagles were common long before Hotel California. They started as four equal partners. Gradually the power shifted toward Henley and Frey, which Meisner and Leadon resented. Leadon left first because the band progressed from country to rock. He also wanted to live a healthy life in a band that lived extremely unhealthy. Even though they made many wonderful songs, things were far from smooth in the studio.

Last part of the documentary begins with the period following the breakup, with brief accounts of the careers of individual members of the band and by the reunion of the band in 1994, followed by the 1990s and 21st century phases of the Eagles. It documents their successful tours, the dispute with Don Felder and the period after his dismissal. It concludes with the band members looking back assessing their actions and career, with contributions from other people who knew them.

Over one billion Christians look to Rome, more than half of all Christians on the planet. But how did a small Jewish sect from the backwoods of 1st-century Palestine, which preached humility and the virtue of poverty, become the established religion of western Europe - wealthy, powerful and expecting unfailing obedience from the faithful? Amongst the surprising revelations, Professor MacCulloch tells how confession was invented by monks on a remote island off the coast of Ireland, and how the Crusades gave Britain the university system. Above all, it is a story of what can be achieved when you have friends in high places.