In Our Time: Science

Melvyn Bragg and guests discuss Laplace (1749-1827) who was a giant in the world of mathematics both before and after the French Revolution. He addressed one of the great questions of his age, raised but side-stepped by Newton: was the Solar System stable, or would the planets crash into the Sun, as it appeared Jupiter might, or even spin away like Saturn threatened to do? He advanced ideas on probability, long the preserve of card players, and expanded them out across science; he hypothesised why the planets rotate in the same direction; and he asked if the Universe was deterministic, so that if you knew everything about all the particles then you could predict the future. He also devised the metric system and reputedly came up with the name 'metre'. WithMarcus du Sautoy Simonyi Professor for the Public Understanding of Science and Professor of Mathematics at the University of OxfordTimothy Gowers Professor of Mathematics at the College de FranceAndColva Roney-Dougal Professor of Pure Mathematics at the University of St AndrewsProducer: Simon Tillotson

Melvyn Bragg and guests discuss the devastating mass extinctions of the Late Devonian Period, roughly 370 million years ago, when around 70 percent of species disappeared. Scientists are still trying to establish exactly what happened, when and why, but this was not as sudden as when an asteroid hits Earth. The Devonian Period had seen the first trees and soils and it had such a diversity of sea life that it’s known as the Age of Fishes, some of them massive and armoured, and, in one of the iconic stages in evolution, some of them moving onto land for the first time. One of the most important theories for the first stage of this extinction is that the new soils washed into oceans, leading to algal blooms that left the waters without oxygen and suffocated the marine life. The image above is an abstract group of the huge, armoured Dunkleosteus fish, lost in the Late Devonian ExtinctionWith Jessica Whiteside Associate Professor of Geochemistry in the Department of Ocean and Earth Science at the University of SouthamptonDavid Bond Professor of Geology at the University of HullAndMike Benton Professor of Vertebrate Paleontology at the School of Life Sciences, University of Bristol.

Melvyn Bragg and guests discuss one of the outstanding French mathematicians and natural philosophers of the 18th Century, celebrated across Europe. Emilie du Châtelet, 1706-49, created a translation of Newton’s Principia from Latin into French that helped spread the light of mathematics on the emerging science, and her own book Institutions de Physique, with its lessons on physics, was welcomed as profound. She had the privileges of wealth and aristocracy, yet had to fight to be taken seriously as an intellectual in a world of ideas that was almost exclusively male. WithPatricia Fara Emeritus Fellow of Clare College, CambridgeDavid Wootton Anniversary Professor of History at the University of YorkAndJudith Zinsser Professor Emerita of History at Miami University of Ohio and biographer of Emilie du Châtelet.Producer: Simon Tillotson

Discover the scientific importance of solar and lunar eclipses and how they provide unique opportunities for studying various phenomena. Explore the early understanding of eclipses in ancient civilizations and their shift to being seen as scientific events. Learn about observations of eclipses away from Earth and their significance in binary stars. Delve into Jules Jansen's discovery of helium during a solar eclipse and hear personal experiences and perceptions of eclipses from the speakers.

Melvyn Bragg and guests discuss Alan Turing (1912-1954) whose 1936 paper On Computable Numbers effectively founded computer science. Immediately recognised by his peers, his wider reputation has grown as our reliance on computers has grown. He was a leading figure at Bletchley Park in the Second World War, using his ideas for cracking enemy codes, work said to have shortened the war by two years and saved millions of lives. That vital work was still secret when Turing was convicted in 1952 for having a sexual relationship with another man for which he was given oestrogen for a year, or chemically castrated. Turing was to kill himself two years later. The immensity of his contribution to computing was recognised in the 1960s by the creation of the Turing Award, known as the Nobel of computer science, and he is to be the new face on the £50 note.WithLeslie Ann Goldberg Professor of Computer Science and Fellow of St Edmund Hall, University of OxfordSimon Schaffer Professor of the History of Science at the University of Cambridge and Fellow of Darwin CollegeAnd Andrew Hodges Biographer of Turing and Emeritus Fellow of Wadham College, OxfordProducer: Simon Tillotson

Melvyn Bragg and guests discuss the theoretical physicist Dirac (1902-1984), whose achievements far exceed his general fame. To his peers, he was ranked with Einstein and, when he moved to America in his retirement, he was welcomed as if he were Shakespeare. Born in Bristol, he trained as an engineer before developing theories in his twenties that changed the understanding of quantum mechanics, bringing him a Nobel Prize in 1933 which he shared with Erwin Schrödinger. He continued to make deep contributions, bringing abstract maths to physics, beyond predicting anti-particles as he did in his Dirac Equation.With Graham Farmelo Biographer of Dirac and Fellow at Churchill College, CambridgeValerie Gibson Professor of High Energy Physics at the University of Cambridge and Fellow of Trinity CollegeAndDavid Berman Professor of Theoretical Physics at Queen Mary University of LondonProducer: Simon Tillotson

Melvyn Bragg and guests discuss the origins of horses, from their dog sized ancestors to their proliferation in the New World until hunted to extinction, their domestication in Asia and their development since. The genetics of the modern horse are the most studied of any animal, after humans, yet it is still uncertain why they only have one toe on each foot when their wider family had more, or whether speed or stamina has been more important in their evolution. What is clear, though, is that when humans first chose to ride horses, as well as eat them, the future of both species changed immeasurably.With Alan Outram Professor of Archaeological Science at the University of ExeterChristine Janis Honorary Professor in Palaeobiology at the University of Bristol and Professor Emerita in Ecology and Evolutionary Biology at Brown UniversityAnd John Hutchinson Professor in Evolutionary Biomechanics at the Royal Veterinary CollegeProducer: Simon Tillotson

Melvyn Bragg and guests discuss the flow of particles from the outer region of the Sun which we observe in the Northern and Southern Lights, interacting with Earth's magnetosphere, and in comet tails that stream away from the Sun regardless of their own direction. One way of defining the boundary of the solar system is where the pressure from the solar wind is balanced by that from the region between the stars, the interstellar medium. Its existence was suggested from the C19th and Eugene Parker developed the theory of it in the 1950s and it has been examined and tested by a series of probes in C20th up to today, with more planned.With Andrew Coates Professor of Physics and Deputy Director in charge of the Solar System at the Mullard Space Science Laboratory, University College LondonHelen Mason OBE Reader in Solar Physics at the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Fellow at St Edmund's CollegeAndTim Horbury Professor of Physics at Imperial College LondonProducer: Simon Tillotson

Melvyn Bragg and guests discuss what happens when parents from different species have offspring, despite their genetic differences. In some cases, such as the zebra/donkey hybrid in the image above, the offspring are usually infertile but in others the genetic change can lead to new species with evolutionary advantages. Hybrids can occur naturally, yet most arise from human manipulation and Darwin's study of plant and animal domestication informed his ideas on natural selection.With Sandra Knapp Tropical Botanist at the Natural History MuseumNicola Nadeau Lecturer in Evolutionary Biology at the University of SheffieldAndSteve Jones Senior Research Fellow in Genetics at University College LondonProducer: Simon Tillotson

Melvyn Bragg and guests discuss the work and ideas of Dorothy Crowfoot Hodgkin (1910-1994), awarded the Nobel Prize in Chemistry in 1964 for revealing the structures of vitamin B12 and penicillin and who later determined the structure of insulin. She was one of the pioneers of X-ray crystallography and described by a colleague as 'a crystallographers' crystallographer'. She remains the only British woman to have won a Nobel in science, yet rejected the idea that she was a role model for other women, or that her career was held back because she was a woman. She was also the first woman since Florence Nightingale to receive the Order of Merit, and was given the Lenin Peace Prize in recognition of her efforts to bring together scientists from the East and West in pursuit of nuclear disarmament.With Georgina Ferry Science writer and biographer of Dorothy HodgkinJudith Howard Professor of Chemistry at Durham UniversityandPatricia Fara Fellow of Clare College, CambridgeProducer: Simon Tillotson