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 definitive discourse with Noam Chomsky on the defining characteristic of our time - the deliberate concentration of wealth and power in the hands of a select few. Chomsky unpacks the principles that have brought us to the crossroads of historically unprecedented inequality - tracing a half century of policies designed to favour the most wealthy at the expense of the majority. "Requiem for the American Dream" is profoundly personal and thought provoking. Chomsky provides penetrating insight into what may well be the lasting legacy of our time - the death of the middle class, and swan song of functioning democracy. A potent reminder that power ultimately rests in the hands of the governed, "Requiem for the American Dream" is required viewing for all who maintain hope in a shared stake in the future.

For centuries, the precise workings of gravity have confounded the greatest scientific minds - from Newton to Faraday and Einstein - and the idea of controlling gravity has been seen as little more than a fanciful dream. Yet in the mid 1990s, UK defence manufacturer BAE Systems began a ground-breaking project code-named Greenglow. Nasa was simultaneously running its own Breakthrough Propulsion Physics Project". It was concerned with potential space applications of new physics, including concepts like 'faster-than-light travel' and 'warp drives'. Looking into the past and projecting into the future, Horizon explores science's long-standing obsession with the idea of gravity control. It looks at recent breakthroughs in the search for loopholes in conventional physics and examines how the groundwork carried out by Project Greenglow has helped change our understanding of the universe. Gravity control may sound like science fiction, but the research that began with Project Greenglow is very much ongoing, and the dream of flying cars and journeys to the stars no longer seems quite so distant.

The use of embryonic stem cells has ignited fierce debate across the spiritual and political spectrum. But what if we could create manmade stem cells - or find super cells in adults that could forever replace embryonic cells and remove the controversy? Today, we are on the brink of a new era - an age where we may be able to cure our bodies of any illness. Stephen Hawking has spent his life exploring the mysteries of the cosmos, now there is another universe that fascinates him - the one hidden inside our bodies - our own personal galaxies of cells." Hawking takes us on a fascinating journey exploring what these wondrous and baffling mechanisms are capable of. He is joined by the scientists who are on the front lines of discovery in this field including Dr. Doris Taylor who is customizing a donor's heart with the recipient's stem cells - her goal is to revolutionize heart transplants, Dr. Paul Lu and Dr. Mark Tuszynski may have created a breakthrough that could cure paralysis, and Dr. Vincent Giampapa who believes that stem cells can be used to stem the tide of aging and create a fountain of youth.

Sagan reflects on the future of humanity and the question of 'who speaks for Earth?' when meeting extraterrestrials. He discusses the very different meetings of the Tlingit people and explorer Jean-François de La Perouse with the destruction of the Aztecs by Spanish conquistadors, the looming threat of nuclear warfare, and the threats shown by destruction of the Library of Alexandria and the murder of Hypatia. The episode ends with an overview of the beginning of the universe, the evolution of life, and the accomplishments of humanity and makes a plea to mankind to cherish life and continue its journey in the cosmos. The Cosmos Update notes the preliminary reconnaissance of planets with spacecraft, the fall of the Berlin Wall and the end of apartheid in South Africa, and measures towards the reduction of nuclear weapons.

By the time he died in 1931, Thomas Alva Edison was one of the most famous men in the world. The holder of more patents than any other inventor in history, Edison had achieved glory as the genius behind such revolutionary inventions as sound recording, motion pictures, and electric light. Edison's curiosity led him to its cutting edge. With just three months of formal schooling, he took on one seemingly impossible technical challenge after another, and through intuition, persistence, and a unique team approach to innovation, invariably solved it." Driven and intensely competitive, Edison was often neglectful in his private life and could be ruthless in business. Challenged by competition in the industry he'd founded, Edison launched an ugly propaganda campaign against his rivals, and used his credibility as an electrical expert to help ensure that high-voltage electrocution became a form of capital punishment. Edison explores the complex alchemy that accounts for the enduring celebrity of America's most famous inventor, offering new perspectives on the man and his milieu, and illuminating not only the true nature of invention, but its role in turn-of-the-century America's rush into the future.