Michael Wood’s epic series moves on to the revolutionary years after 500BC - the Age of the Buddha. Travelling by rail to the ancient cities of the Ganges plain, by army convoy through Northern Iraq, and on down the Khyber Pass, he shows how Alexander the Great’s invasion of India inspired her first empire.

A compelling, dramatic and stylish cinematic journey into snowboarding's unique history and the wider cultural forces that shaped it. Featuring interviews and archival footage with Todd Richards, Gigi Rüf, Terje Haakonsen, Jake Burton, Tom Sims, Stale Sandbech and Craig Kelly.

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.

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.

Frequent security expos feature companies like Megvii and its facial- recognition technology. They show off cameras with A.I. that can track cars, and identify individuals by face, or just by the way they walk. In China it's been projected that over 600 million cameras will be deployed by 2020. Here, they may be used to discourage jaywalking, but they also serve to remind people that the state is watching. Matching with the most advanced artificial intelligence algorithm, they can actually use this data, real-time data, to pick up a face or pick up a action.
A.I. is a technology that can be used for good and for evil. So, how do governments limit themselves in, on the one hand, using this A.I. technology and the database to maintain a safe environment for its citizens, but not to encroach on a individual's rights and privacies?

The enemy gains ground when the massive Tet Offensive catches the Americans by surprise. At Khe Sanh and Pleiku, U.S. troops are under siege. Americans mount a counteroffensive but the shock of the assault ignites anti-war fervour at home.