The former Director-General of the Security Service (MI5), Eliza Manningham-Buller gives the second of her BBC Reith Lectures 2011. In this lecture called " Security" she argues that the security and intelligence services in a democracy have a good record of protecting and preserving freedom.

The former Director-General of the Security Service (MI5), Eliza Manningham-Buller gives the first of her BBC Reith Lectures 2011 called " Terror." On the tenth anniversary of the attacks on the United States on September 11th she reflects on the lasting significance of that day. Was it a "terrorist" crime, an act of war or something different?

The pro-democracy leader, Aung San Suu Kyi, examines what drives people to dissent in the second of the 2011 Reith Lecture series. 'Securing Freedom'.Reflecting on the history of her own party, the National League for Democracy, Aung San Suu Kyi, examines the meaning of opposition and dissident. She also explains her reasons for following the path of non-violence.

The Burmese pro-democracy leader, Aung San Suu Kyi, explores what freedom means in the first of the 2011 Reith Lecture series, 'Securing Freedom'. Reflecting on her own experience under house arrest in Burma, she explores the universal human aspiration to be free and the spirit which drives people to dissent. She also comments on the Arab Spring, comparing the event that triggered last December's revolution in Tunisia with the death of a student during a protest in Burma in 1988.

THE REITH LECTURES 2010 4. The Runaway World In the last Reith Lecture of 2010, Martin Rees, President of the Royal Society and Astronomer Royal, explores how fast our world is moving in the 21st century. Speaking at the Open University in Milton Keynes, the home of online learning, he acknowledges how the internet and other technologies have transformed our lives. Now he calls on politicians and other authorities to provide the funding that will keep the UK among the world's front runners in scientific research and discovery. Without money and without education to attract young people into science, the UK is in danger of falling behind China and other countries in the Far East that are investing heavily in their science and technology sectors. Professor Rees ends his series of lectures evoking memories of the 'glorious' Ely Cathedral, near Cambridge, a monument built to last a thousand years. If we, like the cathedral builders, redirect our energies and focus on the long-term, he believes together we can solve the problems that face our planet, and secure its future for billions of people worldwide and for generations to come. Producer: Kirsten Lass Editor: Sue Ellis.

3. What We'll Never KnowIn the third of this year's Reith Lectures, recorded at the Royal Society during its 350th anniversary year, its President Martin Rees continues to explore the challenges facing science in the 21st century. He stresses there are things that will always lie beyond our sphere of comprehension and we should accept these limits to our knowledge. On the other hand, there are things we've never even dreamt of that will one day be ours to explore and understand. The outcome of the quest for alien life will revolutionise our sense of self in the next two decades. But some things -- like travelling back in time -- will never happen.

Lecture 2: 'Surviving the Century'In the second of this year's Reith Lectures, recorded for the first time in Wales in the National Museum Cardiff, Martin Rees, President of the Royal Society and Astronomer Royal, continues to explore the challenges facing science in the 21st century. Our planet is coming under increasing strain from climate change, population explosion and food shortages. How can we use science to help us solve the crisis that we are moving rapidly towards, as we use up our natural resources ever more quickly? Professor Rees explores the urgent need to substantially reduce our global CO2 emissions, or the atmospheric concentration will reach truly threatening levels. To do this, we need international cooperation, and global funding for clean and green technologies. He calls for the UK to keep one step ahead of other countries by developing technologies to reduce emissions, and says we should take the lead in wave and tidal energy, among other solutions. Science brings innovation but also risk, and random elements including fanatics can abuse new technologies to threaten our planet in ways we never dreamt of. The challenge, for our scientists, governments and people, is to confront the threats to our planet and find the solutions in science.

Lecture 1: ''The Scientific Citizen'In the first of this year's Reith Lectures, entitled Scientific Horizons, Martin Rees, President of the Royal Society, Master of Trinity College and Astronomer Royal, explores the challenges facing science in the 21st century. We are increasingly turning to government and the media to explain the risks we face. But in the wake of public confusion over issues like climate change, the swine 'flu vaccine and, more recently, Iceland's volcanic ash cloud, Martin Rees calls on scientists to come forward and play a greater role in helping us understand the science that affects us all.

Professor Michael Sandel delivers lectures on the prospects of a new politics of the common good, discussing the need for moral and civic renewal in democratic politics, the limitations of market-centered governance, and the importance of democratic deliberation and reflection on preferences. He also addresses the dissatisfaction with politicians and the desire for a new kind of politics.

Professor Michael Sandel delivers four lectures about the prospects of a new politics of the common good. The series is presented and chaired by Sue Lawley. Recorded at the Centre for Life in Newcastle, Sandel considers how we should use our ever-increasing scientific knowledge. New genetic technologies hold great promise for treating and curing disease, but how far we should go in using them to manipulate muscles, moods and gender?