When Sir Richard Peto began work with the late Richard Doll fifty years ago, the UK had the worst death rates from smoking in the world. Smoking was the cause of more than half of all premature deaths of British men. The fact that this country now boasts the biggest decrease in tobacco-linked mortality is in no doubt partly due to Doll and Peto's thirty year collaboration.

Producer: Fiona Hill

Pain, as we know, is highly personal. Some can cope with huge amounts, while others reel in agony over a seemingly minor injury. Though you might feel the stab of pain in your stubbed toe or sprained ankle, it is actually processed in the brain.

That is where Irene Tracey, Nuffield Professor of Anaesthetic Science at Oxford University, has been focussing her attention. Known as the Queen of Pain, she has spent the past two decades unravelling the complexities of this puzzling sensation.

She goes behind the scenes, as it were, of what happens when we feel pain - scanning the brains of her research subjects while subjecting them to a fair amount of burning, prodding and poking.

Her work is transforming our understanding, revealing how our emotions influence our experience of pain, how chronic pain develops and even when consciousness is present in the brain.

Producer: Beth Eastwood

Physicist, Paul Davies is interested in some of the biggest questions that we can ask. What is life? How did the universe begin? How will it end? And are we alone? His research has been broad and far-reaching, covering quantum mechanics, cosmology and black holes. In the 1980s he described the so-called Bunch-Davies vacuum - the quantum vacuum that existed just fractions of a second after the big bang - when particles were popping in and out of existence and nothing was stable.

As the chair of SETI (the Search for Extra-Terrestrial Intelligence) Post Detection Task Group, he’s the person responsible for announcing to the world when we make contact with aliens. He’s now Regents Professor of Physics at Arizona State University in the American south west where he runs research groups studying the evolution of cancer and the origins of life.

Paul Davies talks to Jim al-Khalili about how he applies the principles of physics to these big questions and about how he has worked closely with religious thinkers.

Producer: Anna Buckley

Throughout the history of planet Earth, the element carbon has cycled between the atmosphere, the oceans and the biosphere. This natural cycle has maintained the amount of carbon dioxide in the atmosphere and has allowed life to exist for billions of years. Corinne Le Quéré is a climate scientist who keeps track of where the carbon comes from and where it goes – all on a truly global scale.

Corinne Le Quéré is the founder of the Global Carbon Budget, which each year reports on where carbon dioxide is being emitted and where it is being absorbed around the world. More specifically, she studies the relationship between the carbon cycle and the earth’s climate, and how it is changing.

Corinne is Professor of Climate Change Science at the University of East Anglia. After a degree in physics in her native Canada she became aware of the importance of how carbon moves around the planet and the way it controls the Earth’s climate. This took her to studying meteorology and oceanography and in particular a fascination with the role of the huge Southern Ocean in trapping and holding onto carbon.

She talks to Jim al-Khalili about modelling how carbon moves around the earth and how she communicates the latest research to the public.

How insight with a stick and piece of string led to an engineering adventure taking in spacecraft, military guidance systems and the micro-mechanical devices we use every day in our computers and smartphones.

Ken Gabriel now heads up a large non-profit engineering company, Draper, which cut its teeth building the guidance systems for the Apollo space missions, and is now involved in developing both driverless cars and drug production systems for personalised medicine.

Ken himself has a career in what he might term ‘disruptive engineering’. His research married digital electronics with acoustics - and produced the microphones in our phones and computers. He has a strong track record in defence research and has also worked for Google, taking some of the military research methods into a civilian start up. This led to the development of a new type of modular mobile phone which has yet to go into production.

When the first laser was built in 1960, it was an invention looking for an application. Science fiction found uses for these phenomenally powerful beams of light long before real world applications were developed. Think Star Wars light sabres and people being sliced in half. Today lasers are used for everything from hair removal to state of the art weapons. Working with her supervisor Gerard Mourou in the 1980s, the Canadian physicist, Donna Strickland found a way to make laser pulses that were thousands of times more powerful than anything that had been made before. These rapid bursts of intense light energy have revolutionised laser eye surgery and, it’s hoped, could open the doors to an exciting range of new applications from pushing old satellites out of earth’s orbit to treatments for deep brain tumours. Donna tells Jim Al-Khalili why she wanted to work with lasers and what it feels like to be the first woman to win a Nobel Prize for Physics in 55 years.

Whether it’s a news story or television drama, human violence appals and fascinates in equal measure. Yet few of us choose to dwell on what preoccupies the mind of a perpetrator for long.

Professor Gwen Adshead, however, thinks about little else. As a Forensic Psychotherapist, she works with some of the most vilified and rejected members of society. They are the violent offenders who are detained in prisons and in secure NHS hospitals, like Broadmoor, whose actions have been linked to their mental illness.

Gwen has sought to understand the psychological mechanisms behind their violent behaviour so that she can help them. A pioneer in the field, she provides an environment in which men and women are encouraged to speak the unspeakable and think the unthinkable, in the hope that they will one day be able to change their minds.

Producer: Beth Eastwood

In an astonishing story of a scientific discovery, Greg Winter tells Jim Al-Khalili how decades of curiosity-driven research led to a revolution in medicine. Forced to temporarily abandon his work in the lab when a road rage incident left him with a paralysed right arm, Greg Winter spent several months looking at the structure of proteins. Looking at the stunning computer graphics made the pain in his arm go away. It also led him to a Nobel Prize winning idea: to ‘humanise’ mouse antibodies. A visit to an old lady in hospital made Greg determined to put his research to good use. He fought hard to ensure open access to the technology he invented and set up a start up company to encourage the development of therapeutic drugs. It took years to persuade anyone to fund his Nobel Prize winning idea that led to the creation of an entirely new class of drugs, known as monoclonal antibodies. In 2018, the market for these drugs, which include Humira for rheumatoid arthritis and Herceptin for breast cancer, was worth $70 billion.

Sue Black left home and school when she was 16. Aged 25, she attended an access course to get the qualifications she needed to go to university to study computer science. It was a bit lonely being the only student in a mini- skirt surrounded by a sea of suits, but she came top of the class nonetheless. She signed up to do a PhD (not really knowing what a PhD was) and worked on the ripple effect in software. What happens when you change one bit of code? Does it mess up everything else? A lot of new software is created by building on and adapting existing programmes so these are important questions to ask. In 2003 she embarked on a three year campaign to save Bletchley Park where ten thousand people built some of the first computers and cracked the Enigma code used by the Nazis during World War Two. More than half of the people who worked there were women. No-one had any previous experience of computers. And more than half a century on, there are fewer women working in tech than there were in the 1960s. Sue is determined to change this backwards step. Perhaps another Bletchley Park recruitment drive is needed to encourage more people, women in particular, to engage with tech and help to build our future?

In an ideal (quantum) world, Jim Al-Khalili would be interviewing himself about his life as a scientist but since the production team can’t access a parallel universe, Adam Rutherford is stepping in to ask Jim questions in front of an audience at The Royal Society. Jim and his family left Iraq in 1979, two weeks before Saddam Hussein came to power, abandoning most of their possessions. Having grown up listening to the BBC World Service, he had to drop his ts to fit in at school in Portsmouth where he was one of just three boys in a class of more than a hundred girls. He specialised in nuclear physics and spent fifteen years in front of a computer screen trying to understand an exotic and ephemeral sub-atomic phenomenon known as the halo effect. His ‘little eureka moment’ came in 1996 when Jim discovered that, for the mathematics to add up, these halo nuclei had to be a lot bigger than anyone had thought. It isn’t going to lead to a new kind of non-stick frying pan any time soon but it was exciting, nonetheless. More recently he has become interested in quantum biology. It started as a hobby back in the 1990s when physicists were sceptical and many biologists were unconvinced. Since then evidence has been stacking up. Several studies suggest that lasting quantum mechanical effects could explain photosynthesis, for example. 'It maybe a red herring’ Jim admits but Jim and his team at the University of Surrey are determined to find out if the idea of quantum biology makes sense. Could life itself depend on quantum tunnelling and other bizarre features of the sub-atomic world?