In the fourth episode, Professor Marcus du Sautoy concludes his investigation into the history of mathematics with a look at some of the great unsolved problems that confronted mathematicians in the 20th century. After exploring Georg Cantor's work on infinity and Henri Poincare's work on chaos theory, he sees how mathematics was itself thrown into chaos by the discoveries of Kurt Godel and Paul Cohen, before completing his journey by considering some unsolved problems of maths today, including the Riemann Hypothesis.

Over 133 years in the making, from humble beginnings manufacturing 'Hanufuda' cards came one of the world's most recognized videogame companies, from the birth of Mario and Luigi to Donkey Kong and Zelda... to beating its competition and presenting itself as a platform for quality games and strong values. This is the story of Nintendo.

From the frozen poles to the searing deserts, this episode shows how animals have come up with strategies to survive the uneven amounts of sunlight that fall on our planet over the course of a year. The exception is on the equator, where the duration of day and night remain the same throughout the year. Here, this guaranteed sunlight drives the great diversity of life in the tropical jungles.

Professor Brian Cox journeys across the vastness of time and space revealing epic moments of sheer drama that changed the universe forever.
The series begins this epic exploration of the cosmos with a hymn to the great luminous bodies that bring light and warmth to the universe: the stars. It is estimated that there are two hundred trillion stars in the universe, each playing their part in an epic story of creation- a great saga that stretches from the dawn of time, with the arrival of the first star, through diverse generations until the arrival of our own star, the sun, and a civilization that has grown up in its light.

Everywhere you go, you generate a cloud of data. You're trailing data, everything that you do is producing data. And then there are computers looking at that data that are learning, and these computers are essentially trying to serve you better. They're trying to personalize things to you. They're trying to adapt the world to you. So on the one hand, this is great, because the world will get adapted to you without you even having to explicitly adapt it. There's also a danger, because the entities in the companies that are in control of those algorithms don't necessarily have the same goals as you, and this is where I think people need to be aware that, what's going on, so they can have more control over it.
We came into this new world thinking that we were users of social media and search engines. It didn't occur to us that social media and search engines were actually using us.

David Attenborough discovers the plants that have evolved to shed their dependency on water enabling them to survive in the driest environments. The story begins at midnight in midsummer as David steps into the Princess of Wales Conservatory to witness the extraordinary nocturnal blooming of a cactus. The queen of the night, with its giant flowers, is the centre piece of a stunning symphony of cacti blooms that burst open in the desert (and at Kew) at night. In a mesmerizing 3D slow motion sequence, we discover the extraordinary connections between cacti and their natural pollinators: bats. As the sun rises, David meets other amazing plants. Species like the century plant, the Agave franzosini, which grows steadily for over 50 years, only to then flower itself to death with one mighty telegraph pole sized bloom which literally bursts out of the roof of Kew’s green house.