Time i s a concept which is so familiar, and yet recent discoveries have revealed it to be far stranger than we could have possibly imagined. In the final programme in the series, Brian explores the enigma of time - a phenomenon we take for granted but which is one of the biggest mysteries in the universe. He recalls highlights from his TV series that touch upon this conundrum.

Described as one of the most influential female boxers of all time, helping legitimize women’s participation in the sport, Christy Martin shocked the world by becoming a superstar after winning a blood-soaked undercard match at the Mike Tyson/Frank Bruno fight in 1996.
After her meteoric rise, the film breaks down Christy’s incredible fight for survival both in and out of the ring as she battled substance abuse, domestic violence and a harrowing brush with death. We also see Christy’s struggle with her sexual orientation and her journey of self-discovery. This is a story stranger than fiction, that must be seen to be believed.

We learn as much from victory as we do from loss. We employ strategies to gain the advantage, unconventional methods to overwhelm adversaries. One dedicated force steeped in mystique has always been part of war. Special operations, elite and unseen. Their presence felt by lethal attack. From the biblical era to the future of warfare, the battle environment is reshaped and redefined by special operations. Special Operations soldiers have come out of the trenches and are entering new domains of warfare.

The true, stranger-than-fiction, adventure of eight visionaries who in 1991 spent two years quarantined inside of a self-engineered replica of Earth's ecosystem called Biosphere 2.
The experiment was a worldwide phenomenon, chronicling daily existence in the face of life threatening ecological disaster and a growing criticism that it was nothing more than a cult. The bizarre story is both a cautionary tale and a hopeful lesson of how a small group of dreamers can potentially re-imagine a new world.

Dr Hannah Fry explores a paradox at the heart of modern maths, discovered by Bertrand Russell, which undermines the very foundations of logic that all of maths is built on. These flaws suggest that maths isn't a true part of the universe but might just be a human language - fallible and imprecise. However, Hannah argues that Einstein's theoretical equations, such as E=mc2 and his theory of general relativity, are so good at predicting the universe that they must be reflecting some basic structure in it. This idea is supported by Kurt Godel, who proved that there are parts of maths that we have to take on faith.
Hannah then explores what maths can reveal about the fundamental building blocks of the universe - the subatomic, quantum world. The maths tells us that particles can exist in two states at once, and yet quantum physics is at the core of photosynthesis and therefore fundamental to most of life on earth - more evidence of discovering mathematical rules in nature. But if we accept that maths is part of the structure of the universe, there are two main problems: firstly, the two main theories that predict and describe the universe - quantum physics and general relativity - are actually incompatible; and secondly, most of the maths behind them suggests the likelihood of something even stranger - multiple universes.
We may just have to accept that the world really is weirder than we thought, and Hannah concludes that while we have invented the language of maths, the structure behind it all is something we discover. And beyond that, it is the debate about the origins of maths that has had the most profound consequences: it has truly transformed the human experience, giving us powerful new number systems and an understanding that now underpins the modern world.

Deep in the mountains of West Virginia, the Green Bank Observatory has been receiving a mysterious signal from deep space. A team of astronomers has been detecting high-energy bursts erupting from unknown sources far off in space since years ago. But one of them is different from the rest. They call it FRB 121102.
What is actually giving rise to this very powerful flash? Could this be a message from an advanced civilization, or is it a much stranger and violent occurrence? Visit the largest steerable radio telescope on the planet for answers.