Philip Ball tells the story of Alexis Carrel, the French surgeon who worked to preserve life outside the body and create an immortal chicken heart in a dish. His quest was to renew ageing flesh, repair and rebuild our bodies and keep them healthy far beyond the usual human lifespan. In the early twentieth century his science was pioneering but his mission to achieve eternal life was underpinned by a dark and terrifying agenda. Carrel was a racist who advocated eugenics to preserve the superior civilisation of the West. Philip Ball discusses the history and cultural impact of the tissue culture techniques developed by Carrel with social historian Professor Hannah Landecker of the University of California at Los Angeles. And he finds out about the legacy of Carrel's research from Dr Madeline Lancaster of Cambridge University, one of the pioneers of the growth of brain organoids from stem cells; small clusters of neurons and other cells, rather like mini organs no bigger than a dried pea.

Philip Ball tells the story of Ramon Llull, the Medieval prophet of computer science. During the time of the Crusades Llull argued that truth could be automated and used logic over force to prove the existence of the Christian God. It was a dangerous idea that got him thrown into prison and threatened with execution but today he is hailed, not as a prophet of the Christian faith, but of computer science. Philip Ball talks to historian Pamela Beattie of the University of Louisville in Kentucky about Ramon Llull's life and times in 13th century Catalonia, and to mathematician and Simonyi Professor for the Public Understanding of Science at Oxford University, Marcus du Sautoy, about the legacy of Llull's ideas in combinatorics, a branch of mathematics that explores how we can arrange a set of objects. Note: Many thanks to Carter Marsh Co for the recording of mechanical sounds.

Lindsey Fitzharris tells the story of Ignaz Semmelweiss, the hand washer. In a world that had no understanding of germs, he tried to apply science to halt the spread of infection. Ignaz Semmelweis observed that many young medical students at his hospital in Vienna went directly from an autopsy, still covered in contaminated dead flesh, to attend pregnant women. Could this be the reason for such high maternal mortality rates from conditions like puerperal fever? Believing that the disease was caused by “infective material” from a dead body, Semmelweiss set up a basin filled with chlorinated lime solution in his hospital and began saving women’s lives with three simple words: ‘wash your hands’. He was demonised by his colleagues for his efforts, but today, he is known as the “Saviour of Mothers.” Lindsey Fitzharris discusses some of the common myths surrounding the story of Semmelweiss with Dr Barron H. Lerner of New York University Langone School of Medicine. And she talks to Professor Val Curtis, Director of the Environmental Health Group at the London School of Hygiene and Tropical Medicine, who has studied the amount of hand washing by medical staff in hospitals today. Main Image: Lindsey Fitzharris Credit: T. K. Smith

Philip Ball tells the story of Madame Lavoisier; translator of oxygen. At a time when science was almost a closed book to women, Madame Marie Anne Lavoisier’s skills were indispensable. A translator, illustrator and critic of scientific papers, she learnt chemistry herself and helped her husband Antoine Lavoisier develop his theory of the role played by oxygen in combustion. As modern science was taking shape it lacked any universal language, so communication in many tongues was vital to stay ahead of the game. Even today there is debate as to who can really be considered the discoverer of oxygen, but Madame Lavoisier’s gift for translation helped her husband compete against English rivals and banish their theories. Come the French Revolution however, Anton was branded a traitor to the state and sentenced to death. By a cruel twist of fate Marie lost both husband and father to the guillotine on the same day. Philip Ball talks to Patricia Fara at the University of Cambridge, about the largely unrecognised contribution that women like Marie Anne Lavoisier made to the early days of modern science, and to Michael Gordin of Princeton University about the importance of scientific translation in the past and how it features today,

Galileo famously insisted in the early seventeenth century that the Earth goes round the Sun and not vice versa – an idea that got him into deep trouble with the Catholic Church. In 1633 Galileo was put in trial for heresy by the Inquisition, and was threatened with imprisonment, or worse, if he didn’t recant. Galileo spent the rest of his days under house arrest and is now seen by some as a near-martyr to science in the face of unyielding religious doctrine. But the discovery of a letter questions the received version of events. Philip Ball tells the story of the relationship between Galileo, the church and his fellow professors. Philip talks to science historians Professor Paula Findlen of Stanford University and Professor Mary Jane Rubenstein of Wesleyan University about Galileo's time and about the history of the relationship between science and religion.

Philip Ball's story is of Ibn al-Haytham, the first scientist, and his book of optics that defined how we see.

Naomi Alderman's Science Story reveals how Lady Mary Wortley Montagu experimented on her own child in a quest to prove that smallpox inoculation works. Born in 1689 in a position of some power and influence, Lady Mary travelled to Constantinople as the wife of the ambassador to Turkey and witnessed 'variolation parties'. Here 'a nut shell' of virus on a needle is put in an opened vein to infer immunity. Having lost her own brother to smallpox and survived with terrible scaring herself, Lady Mary knew first hand the dangers of the deadly disease. She became the first person to bring smallpox inoculation to the West. Medical historian Lindsey Fiztharris tells the remarkable story of how condemned prisoners are given the opportunity to escape execution under the orders of King George I if they are given the virus and survive. Tim Spector, Professor of Genetic Epidemiology at Kings College, London, and Naomi discuss some of today's counter intuitive treatments, such as faecal transplants.

Philip Ball reveals the tale of a small booklet 'On The Six-Cornered Snowflake", written by Johannes Kepler as a New Year's gift. The C17th astronomer wished to explain the intricate and symmetrical shape of winter's tiny stars of snow. His insightful speculations about minerals and geometry was the beginning of the modern understanding of crystals.

Naomi Alderman's tale is of Lucretius, author of a 2000 year old poem that theorised about atoms and the natural world. Written in the first century BCE, during a chaotic and frightening time when the Roman Republic was collapsing, Lucretius encouraged people to feel free through contemplating the physics of the Universe. Naomi learns that many of the theories still hold water today and that the poem, De Rerum Natura, is an epic beautiful and persuasive piece of work.

Eddington's Eclipse and Einstein's Celebrity Philip Ball's tale is of a solar eclipse 100 years ago observed by Arthur Eddington, a British astronomer who travelled to the remote island of Principe off the coast of West Africa and saw the stars shift in the heavens. His observations supplied the crucial proof of a theory that transformed our notions of the cosmos and turned a German physicist named Albert Einstein into an international celebrity. But this is also a tale of how a Quaker tried to use science to unite countries. The reparations imposed on Germany after the war extended into science too as many in Great Britain and other Allied nations felt that German science should be ostracised from the international community. As a Quaker, Eddington wanted just the opposite: to see peaceful cooperation restored among nations. Producer: Erika Wright