Julian of Norwich

Melvyn Bragg and guests discuss the rise of the idea of perpetual motion and its decline, in the 19th Century, with the Laws of Thermodynamics. For hundreds of years, some of the greatest names in science thought there might be machines that could power themselves endlessly. Leonardo Da Vinci tested the idea of a constantly-spinning wheel and Robert Boyle tried to recirculate water from a draining flask. Gottfried Leibniz supported a friend, Orffyreus, who claimed he had built an ever-rotating wheel. An increasing number of scientists voiced their doubts about perpetual motion, from the time of Galileo, but none could prove it was impossible. For scientists, the designs were a way of exploring the laws of nature. Others claimed their inventions actually worked, and promised a limitless supply of energy. It was not until the 19th Century that the picture became clearer, with the experiments of James Joule and Robert Mayer on the links between heat and work, and the establishment of the First and Second Laws of Thermodynamics.With Ruth Gregory Professor of Mathematics and Physics at Durham UniversityFrank Close Professor Emeritus of Physics at the University of OxfordandSteven Bramwell Professor of Physics and former Professor of Chemistry at University College LondonProducer: Simon Tillotson.

24 Sep 201545min

Born near Mexico City in 1907, Frida Kahlo is considered one of Mexico's greatest artists. She took up painting after a bus accident left her severely injured, was a Communist, married Diego Rivera, a celebrated muralist, became friends with Trotsky and developed an iconic series of self-portraits. Her work brings together elements such as surrealism, pop culture, Aztec and Indian mythology and commentary on Mexican culture. In 1938, artist and poet Andre Breton organised an exhibition of her work in New York, writing in the catalogue, "The Art of Frida Kahlo is a ribbon around a bomb." She was not as widely appreciated during her lifetime as she has since become, but is now one of the most recognised artists of the 20th century. WithPatience Schell Chair in Hispanic Studies at the University of AberdeenValerie Fraser Emeritus Professor of Latin American Art at the University of EssexAndAlan Knight Emeritus Professor of the History of Latin America at the University of OxfordProducer: Simon Tillotson.

9 Jul 201545min

Frederick the Great ruled Prussia from 1740 until his death in 1786. Born in 1712, he increased the power of the state, he made Prussia the leading military power in Europe and his bold campaigns had great implications for the European political landscape. An absolute monarch in the age of enlightenment, he was a prolific writer, attracted figures such as Voltaire to his court, fostered education and put Berlin firmly on the cultural map. He was much admired by Napoleon and was often romanticised by German historians, becoming a hero for many in united Germany in the 19th and 20th centuries. Others, however, vilified him for aspects such as his militarism and the partition of Poland. With Tim Blanning Emeritus Professor of Modern European History at the University of CambridgeKatrin Kohl Professor of German Literature at the University of Oxford and a Fellow of Jesus CollegeAnd Thomas Biskup Lecturer in Early Modern History at the University of HullProducer: Simon Tillotson.

2 Jul 201548min

In 1977, scientists in the submersible "Alvin" were exploring the deep ocean bed off the Galapagos Islands. In the dark, they discovered hydrothermal vents, like chimneys, from which superheated water flowed. Around the vents there was an extraordinary variety of life, feeding on microbes which were thriving in the acidity and extreme temperature of the vents. While it was already known that some microbes are extremophiles, thriving in extreme conditions, such as the springs and geysers of Yellowstone Park (pictured), that had not prepared scientists for what they now found. Since the "Alvin" discovery, the increased study of extremophile microbes has revealed much about what is and is not needed to sustain life on Earth and given rise to new theories about how and where life began. It has also suggested forms and places in which life might be found elsewhere in the Universe. With Monica Grady Professor of Planetary and Space Sciences at the Open UniversityIan Crawford Professor of Planetary Science and Astrobiology at Birkbeck University of LondonAndNick Lane Reader in Evolutionary Biochemistry at University College LondonProducer: Simon Tillotson.

25 Jun 201546min

The story of Jane Eyre is one of the best-known in English fiction. Jane is the orphan who survives a miserable early life, first with her aunt at Gateshead Hall and then at Lowood School. She leaves the school for Thornfield Hall, to become governess to the French ward of Mr Rochester. She and Rochester fall in love but, at their wedding, it is revealed he is married already and his wife, insane, is kept in Thornfield's attic. When Jane Eyre was published in 1847, it was a great success and brought fame to Charlotte Bronte. Combined with Gothic mystery and horror, the book explores many themes, including the treatment of children, relations between men and women, religious faith and hypocrisy, individuality, morality, equality and the nature of true love. WithDinah Birch Professor of English Literature and Pro-Vice-Chancellor for Research at the University of LiverpoolKaren O'Brien Vice Principal and Professor of English Literature at King's College LondonAndSara Lyons Lecturer in Victorian Literature at the University of KentProducer: Simon Tillotson.

18 Jun 201545min

A moral theory that emphasises ends over means, Utilitarianism holds that a good act is one that increases pleasure in the world and decreases pain. The tradition flourished in the eighteenth and nineteenth centuries with Jeremy Bentham and John Stuart Mill, and has antecedents in ancient philosophy. According to Bentham, happiness is the means for assessing the utility of an act, declaring "it is the greatest happiness of the greatest number that is the measure of right and wrong." Mill and others went on to refine and challenge Bentham's views and to defend them from critics such as Thomas Carlyle, who termed Utilitarianism a "doctrine worthy only of swine."WithMelissa Lane The Class of 1943 Professor of Politics at Princeton UniversityJanet Radcliffe Richards Professor of Practical Philosophy at the University of OxfordandBrad Hooker A Professor of Philosophy at the University of ReadingProducer: Simon Tillotson.

11 Jun 201543min

In the Middle Ages, Prester John was seen as the great hope for Crusaders struggling to hold on to, then regain, Jerusalem. He was thought to rule a lost Christian kingdom somewhere in the East and was ready to attack Muslim opponents with his enormous armies. There was apparent proof of Prester John's existence, in letters purportedly from him and in stories from travelers who claimed they had met, if not him, then people who had news of him. Most pointed to a home in the earthly paradise in the Indies, outside Eden, with fantastical animals and unimaginable riches. Later, Portuguese explorers thought they had found him in Ethiopia, despite the mystified denials of people there. Melvyn Bragg asks why the legend was so strongly believed for so long, and what facts helped sustain the myths.WithMarianne O'Doherty Associate Professor in English at the University of SouthamptonMartin Palmer Director of the International Consultancy on Religion, Education, and CultureAndAmanda Power Senior Lecturer in Medieval History at the University of Sheffield.Producer: Simon Tillotson.

4 Jun 201544min

While glass items have been made for at least 5,000 years, scientists are yet to explain, conclusively, what happens when the substance it's made from moves from a molten state to its hard, transparent phase. It is said to be one of the great unsolved problems in physics. While apparently solid, the glass retains certain properties of a liquid. At times, ways of making glass have been highly confidential; in Venice in the Middle Ages, disclosure of manufacturing techniques was a capital offence. Despite the complexity and mystery of the science of glass, glass technology has continued to advance from sheet glass to crystal glass, optical glass and prisms, to float glasses, chemical glassware, fibre optics and metal glasses.With:Dame Athene Donald Professor of Experimental Physics at the University of Cambridge and Master of Churchill College, CambridgeJim Bennett Former Director of the Museum of the History of Science at the University of Oxford and Keeper Emeritus at the Science MuseumPaul McMillan Professor of Chemistry at University College LondonProducer: Simon Tillotson.

28 Mai 201545min