By our third year, most of us will have learned to count. Once we know how, it seems as if there would be nothing to stop us counting forever. But, while infinity might seem like an perfectly innocent idea, keep counting and you enter a paradoxical world where nothing is as it seems. Mathematicians have discovered there are infinitely many infinities, each one infinitely bigger than the last. And if the universe goes on forever, the consequences are even more bizarre. In an infinite universe, there are infinitely many copies of the Earth and infinitely many copies of you. Older than time, bigger than the universe and stranger than fiction. This is the story of infinity.

A stellar explosion, the supernova is the sensational death of a star. It can shine as bright as 100 billion Suns and radiate as much energy as the Sun would emit over 10 billion years. Jets of high-energy light and matter are propelled into space and can cause massive Gamma Ray Bursts and emit intense X-ray radiation for thousands of years. Astronomers believe that this process creates the very building blocks of planets, people and plants. Meet the world's leading Supernova hunters, and take a look at recorded supernovas throughout history.

1916. The war is raging in Europe and stretches from the trenches in France to the Italian Alps and the Balkans, and beyond to the gates of the Eastern world. The conflict becomes industrial, and millions of shells rain down on the battlefields; Verdun and the Somme are the deadliest battles in this second year of the war. Who can stop this infernal machine?

In ‘Who will we be?’ Dr. David Eagleman journeys into the future, and asks what’s next for the human brain, and for our species. We stand at a major turning point, one where we might take control of our own development. We face a future of uncharted possibilities in which our relationship with our own body, our relationship with the world, the very basic nature of who we are is set to be transformed. For thousands of generations, humans have lived the same life cycle over and over. We are born, we control a fragile body, we experience a limited reality, and we die. But science and technology are giving us tools to transcend that evolutionary story. Our brains don't have to remain as we have inherited them. We are capable of extending our reality, of inhabiting new bodies, and possibly shedding our physical forms altogether. And we are discovering the tools to shape our own destiny. Who we become is up to us.

The Dutch Golden Age saw map-making reach a fever pitch of creative and commercial ambition. This was the era of the first ever Atlases - elaborate, lavish and beautiful. This was the great age of discovery and marked an unprecedented opportunity for mapmakers who sought to record and categorise the newly acquired knowledge of the world. Rising above the many mapmakers in this period was Gerard Mercator, inventor of the Mercator projection, who changed mapmaking forever when he published his collection of world maps in 1598 and coined the term 'Atlas'. The programme looks at some of the largest and most elaborate maps ever produced, from the vast maps on the floor of the Royal Palace in Amsterdam, to the 24 volume atlas covering just the Netherlands, to the largest Atlas in the world, The Klencke Atlas. It was made for Charles II to mark his restoration in 1660. But whilst being one of the British Libraries most important items, it is also one of its most fragile so hardly ever opened. This is a unique opportunity to see inside this enormous and lavish work, and see the world through the eyes of a King.

The episode begins with Tyson describing how pattern recognition manifested in early civilization as using astronomy and astrology to predict the passing of the seasons, including how the passage of a comet was often taken as an omen. Tyson continues to explain that the origin of comets only became known in the 20th century due to the work of Jan Oort and his hypothesis of the Oort cloud. Tyson then continues to relate the collaboration between Edmond Halley and Isaac Newton in the last part of the 17th century in Cambridge. The collaboration would result in the publication of Philosophiæ Naturalis Principia Mathematica, the first major work to describe the laws of physics in mathematical terms, despite objections and claims of plagiarism from Robert Hooke and financial difficulties of the Royal Society of London. Tyson explains how this work challenged the prevailing notion that God had planned out the heavens, but would end up influencing many factors of modern life, including space flight. Tyson further describes Halley's contributions including determining Earth's distance to the sun, the motion of stars and predicting the orbit of then-unnamed Halley's Comet using Newton's laws. Tyson contrasts these scientific approaches to understanding the galaxy compared to what earlier civilizations had done, and considers this advancement as mankind's first steps into exploring the universe. The episode ends with an animation of the Milky Way and Andromeda galaxies' merging based on the principles of Newton's laws.