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.

What if aliens landed on Earth? Much of science fiction explores the moment of first contact – what will people do when the aliens land? From H. G. Wells’ pioneering The War of the Worlds to Independence Day, Men in Black, and District 9, Invasion deals with our fears of alien invasions of earth. David Tennant explains the appeal of Doctor Who’s Daleks and Cybermen while John Carpenter and Chris Carter explore the rich appeal of the paranoia fuelled by hidden aliens with The Thing and The X-Files. It also asks, what if the monsters were our own creation? With the aid of rarely seen animation tests, Phil Tippett takes us behind the scenes in the creation of the dinosaurs of Jurassic Park. But not all invasions are hostile. Peter Coyote and Richard Dreyfuss discuss the creation of Spielberg’s spellbinding classics E.T. the Extra-Terrestrial and Close Encounters of the Third Kind. There is more than one kind of invasion.

Filmmaker Jonathan Reiss offers a multilingual look at the evolution of graffiti in a documentary that begins by examining ancient rock paintings and traces the trend straight through to the works of Picasso and 1970s-era New York City hip-hop culture. Shot on five continents using guerilla filmmaking techniques, Bomb It aims to give viewers a newfound appreciation of graffiti culture by exploring the origins of street art and interviewing the artists about their tactics and motivations.

What if we could explore the vastness of Space? Science fiction has always fed upon our need to explore – to wonder what is out there. Space journeys from Jules Verne’s earliest ideas about attempts to leave our planet, to the Star Wars far away galaxy through to Nichelle Nichols revealing how her groundbreaking role as Lt. Uhura in Star Trek led to her participation in the recruitment of NASA’s astronauts. It explores the deep sea inspiration for Avatar, finds out why Ursula K Le Guin wrote The Left Hand of Darkness and discovers how Stanley Kubrick was able to make 2001: A Space Odyssey seem so believable. In addition, the program looks at the way Dune and The Mars Trilogy embraced the challenge of world building and discusses the appeal of the beaten up ‘dirty space’ of Dark Star and Firefly. From the horrifying scenes of Alien, to the epic spectacle of Star Wars, this is a journey to the stars and the alien encounters that await us there.

Sir Roger Penrose is more than just a fan of MC Escher's mind-bending art. During the course of a long creative collaboration, the British mathematician and the Dutch artist exchanged ideas and inspirations. Some of Escher's most iconic images have their origin in Penrose's mathematical sketches - while the artist's work has served as a starting point for the professor's own explorations of new scientific ideas". To coincide with the first ever Escher retrospective in the UK, Penrose takes us on a personal journey through Escher's greatest masterpieces - marvelling at his intuitive brilliance and the penetrating light it still sheds on complex mathematical concepts.

The National Gallery in London is one of the great museums of the world with 2400 paintings from the 13th to the end of the 19th century. Almost every human experience is represented in one or the other of the paintings. The sequences of the film show the public in various galleries; the education programs, and the scholars, scientists and curators, studying, restoring and planning the exhibitions. The relation between painting and storytelling is explored.