Recently, the Event Horizon Telescope project captured the first image ever of a black hole. Now, new discoveries might finally reveal how supermassive black holes are made, and using the latest technology, experts are on the verge of understanding how these monsters grow and how they affect life on our planet.
Supermassive black holes: Gargantuan monsters that lurk at the center of galaxies. Right now you are travelling at half a million miles an hour around a giant black hole four million times the mass of the sun. But there's a mystery about these colossal beasts. We have no idea where they came from. How did they get so big so quickly?

The search for climate change solutions requires passion, resources and a sense of urgency -- three qualities Bill Gates clearly possesses. Bill has founded a start-up called TerraPower. After extensive computer modelling, the idea showed promise. Its new reactor greatly reduced the chance of human error. Fuelled by depleted uranium, the travelling wave reactor functions like a slow-burning candle and requires refuelling only once every decade. Bill and his team believed they had finally developed the ideal energy source, a reactor that was clean, efficient, and most importantly, safe.

35 years after the Chernobyl disaster, Ben Fogle travels to the most radioactive place on Earth. He spends a week living alone inside the Chernobyl Exclusion Zone, gaining privileged access to the doomed Control Room 4 where the disaster first began to unfold.
'The planet faces unprecedented challenges - many of them, like Chernobyl, of our own making. What I've discovered in Chernobyl is that nature's reclaiming it. This is the greatest, accidental rewilding project of the globe. For me, the really exciting part of the Chernobyl story is the accidental hope that came from it. '

The most innovative area of human motion lies not on Earth, but with the exploration of space. Space is the most hostile environment we know. Navigating it involves crossing unprecedented distances. It's the greatest engineering challenge humanity has ever undertaken.
Meet the pioneers who've dreamed of reaching other worlds, pushing the boundaries of space exploration, and the private space entrepreneurs jostling to offer the tantalizing prospect of cheap, frequent travel beyond the atmosphere into Earth orbit.

Einstein's world-shaking Theory of Relativity says that time travel is perfectly possible -- if you're going forward in time. Finding a way to travel backwards requires breaking the speed of light, which so far seems impossible. But now, strange-but-true phenomena such as quantum nonlocality (where particles instantly teleport across vast distances) may give us a way to make the dream of traveling back and forth through time a reality. Step into a time machine and rewrite history, bring loved ones back to life, control our destinies. But if succeed, what are the consequences of such freedom? Will we get trapped in a plethora of paradoxes and multiple universes that will destroy the fabric of the universe?

In this second episode we travel from January to the March equinox. Kate Humble gets closer to the Sun than she has ever been before, whilst Helen Czerski visits a place that gets some of the biggest and fastest snowstorms on Earth.