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.

A group of brave individuals risk their lives to save the last of the world's mountain gorillas; in the midst of renewed civil war and a scramble for Congo's natural resources." Virunga National Park in the Congo is a place of unique natural beauty. It is the home to a plethora of wonderful animals and vegetation but as is so often the way, it has several serious problems that threaten it. It's the location of human violence, corruption and exploitation. The disasters that specifically loom are two different groups, the M23 and SOCO International. The former are a violent rebel force who engages in an ongoing civil war with the Congolese government and the latter are a British energy company who specialise in oil exploration. Both M23 and SOCO invade the park in their own ways and neither seems very interested in the laws that have been set up to protect the flora and fauna that exist there, far less the people who live there. It seems hardly surprising in the case of M23, as they are a paramilitary organisation who can hardly be expected to be concerned with such things but it is the more legitimate big business SOCO who seem more worrying if anything. We discover in fact that they have been involved in a bribery campaign, utilising M23 as enforcers. It's a very murky situation where big money walks all over an impoverished nation and disregards a natural space that they can see no value in in their pursuit of financial profit.

Dark energy - the mysterious force that is unexpectedly causing the universe's expansion to speed up. The effects of dark energy were discovered in 1998 but physicists still don't know what it is. Worse, its very existence calls into question Albert Einstein's general theory of relativity - the cornerstone of modern physics. The hunt for the identity of dark energy is on". Experiments on earth and in space generate data that might provide a clue, but there are also hopes that another Einstein might emerge - someone who can write a new theory explaining the mystery of the dark energy.

Iain Stewart investigates a new and controversial energy rush for the natural gas found deep underground. Getting it out of the ground involves hydraulic fracturing - or fracking. We travel to America to find to find out what it is, why it is a potential game changer and what we can learn from the US experience". Sometimes, this is right under the places people live in. He meets some of the people who have become rich from fracking as well as the communities worried about the risks. Director Jeff Wilkinson

Explore the latest science behind the headlines and the coolest scientific developments that impact our lives. Technology catapults to new heights in 2015, going faster and further than ever before. We have canvassed the world in search of the best and most fascinating science and tech stories of the year for 2015 YEAR IN SCI-TECH". This action-packed hour of fun and intrigue revisits the world’s first glimpse of Pluto and images of water on Mars while exploring what this all could mean for intelligent life in the universe – all while earthling’s inch closer to becoming actual space tourists. Throughout the hour, we revisit the year’s most amazing techological feats and scientific discoveries, including new and elusive animal species discovered deep under the ocean, as well as the hottest tech trends – from hover boards to driverless cars and trucks, and the newest advances in mind-blowing virtual reality.

25 years ago, NASA launched one of the most ambitious experiments in the history of astronomy: the Hubble Space Telescope. In honor of Hubble's landmark anniversary, know the remarkable story of the telescope that forever changed our understanding of the cosmos and our place in it". But amazingly, when the telescope first sent images back to earth, it seemed that the entire project was a massive failure; a one-millimeter engineering blunder had turned the billion-dollar telescope into an object of ridicule. It fell to five heroic astronauts in a daring mission to return Hubble to the cutting edge of science. Hear from the scientists and engineers on the front line who tell the amazing Hubble story as never before. This single telescope has helped astronomers pinpoint the age of the universe, revealed the birthplace of stars and planets, advanced our understanding of dark energy and cosmic expansion, and uncovered black holes lurking at the heart of galaxies. For more than a generation, Hubble's stunning images have brought the beauty of the heavens to millions, revealing a cosmos richer and more wondrous than we ever imagined. Join us for the story of this magnificent machine and its astonishing discoveries.