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.

Whales have long been a profound mystery to us. They live in a world so removed from our own that we can barely imagine their lives. Their environment is different, their senses are different, their relationships are different. How might such almost alien creatures see the world?, Narrated by David Attenborough.

In the summer of 1983, just days before the birth of his first son, writer and theologian John Hull went blind. In order to make sense of the upheaval in his life, he began keeping a diary on audiocassette. Upon their publication in 1990, Oliver Sacks described the work as 'the most extraordinary, precise, deep and beautiful account of blindness I have ever read. It is to my mind a masterpiece.'
With exclusive access to these original recordings, Notes On Blindness encompasses dreams, memory and imaginative life, excavating the interior world of blindness.

Earth may seem like the most hospitable planet in the solar system. But look again. Startling new discoveries reveal the blue planet has been plagued by more chaos and destruction than scientists once imagined. Stand on the Earth billions of years ago as a primitive planet called Theia slams into it. Shiver as our entire globe is frozen over like a gigantic snowball. Feel the heat as mammoth volcanoes scorch the landscape and darken the sky. From a cosmic gamma ray burst frying away the ozone layer to an Everest-size asteroid slamming into the ocean, we'll reveal new information about how these unparalleled events drove life to the brink of total extinction. Out of this continuous devastation, how has our planet--and life--got to where it is today? Are the worst days behind us--or lurking in the distant future?

Moving on to Ethiopia 3.2 million years ago, we witness the beginnings of mankind via a group of australopithecus - a type of ape which, like us, walks upright on two legs. But unlike us, these early members of the human family weren't predators, they were prey. Things get worse for the group as they are hunted by a sabre-tooth cat called dinofelis and fall victim to other dangers such as malaria, rival australopithecus and a rampaging 14-tonne deinotherium.

Even 2,000 years after his death, General Hannibal's battle strategies are still studied today. But of all his military feats, perhaps his greatest was leading his massive Carthaginian army of men and three-dozen elephants across the Alps and into the heartland of Rome in 218 B.C. Until now, the route they took has been a matter of dispute, but thanks to modern-day technology, geomorphologist Bill Mahaney and microbiologist Chris Allen believe they've accurately traced this ancient journey.