In Our Time: Science

Misha Glenny and guests discuss one of the wonders of the natural world. In 1875 in the western Pacific, the crew of HMS Challenger discovered the Mariana Trench which turned out to be deeper than Everest is high, by two kilometres. Trenches like Mariana form when one tectonic plate slips under another and heads down and there are around fifty of them globally. While at one time some thought it was too dark and deep for life there and others wildly imagined monsters, the truth has turned out to be much more surprising. With Heather Stewart, Director of Kelpie Geoscience and Associate Professor at the University of Western Australia Jon Copley Professor of Ocean Exploration and Science Communication at the University of Southampton And Alan Jamieson Director of the Deep Sea Research Centre at the University of Western Australia Producer: Simon Tillotson Reading list: Susan Casey, The Underworld: Journeys to the Depths of the Ocean (Doubleday, 2023) Jon Copley, Deep Sea: 10 Things You Should Know (Orion Books,…

Melvyn Bragg and guests discuss the evolution of lungs and of the first breaths, which can be traced back 400 million years to when animal life spread from rock pools and swamps onto land, as some fish found an evolutionary advantage in getting their oxygen from air rather than water. Breathing with lungs may have started with fish filling their mouths with air and forcing it down into sacs in their chests, like the buccal pumping that frogs do now, and slowly their swimming muscles adapted to work their lungs like bellows. While lungs developed in different ways, there are astonishing continuities: for example, the distinct breathing system that helps tiny birds fly thousands of miles now is also the one that once allowed some dinosaurs to become huge; our hiccups are vestiges of the flight reaction in fish needing more oxygen; and we still breathe through our skins, just not enough to meet our needs. With: Steve Brusatte Professor of Palaeontology and Evolution at the University of Edinburgh Emily Rayfield…

Melvyn Bragg and guests discuss the decisive role of one of the great 20th Century physicists in solving the question of nuclear fission. It is said that Meitner (1878-1968) made this breakthrough over Christmas 1938 while she was sitting on a log in Sweden during a snowy walk with her nephew Otto Frisch (1904-79). Both were Jewish-Austrian refugees who had only recently escaped from Nazi Germany. Others had already broken uranium into the smaller atom barium, but could not explain what they found; was the larger atom bursting, or the smaller atom being chipped off or was something else happening? They turned to Meitner. She, with Frisch, deduced the nucleus really was splitting like a drop of water into a dumbbell shape, with the electrical charges at each end forcing the divide, something previously thought impossible, and they named this ‘fission’. This was a crucial breakthrough for which Meitner was eventually widely recognised if not at first. With Jess Wade A Royal Society University Research Fellow…

Since plants have to mate and produce offspring while rooted to the spot, they have to be pollinated – by wind, water, or animals – most commonly insects. They use a surprising array of tricks to attract pollinators: striking colours, iridescent light effects, and enticing scents, to name but a few. Insects, on the other hand, do not seek to pollinate plants – they are looking for food; so plants make sure it’s worth their while. Insects are also remarkably sophisticated in their ability to find, recognise and find their way inside flowers. So pollination has evolved as a complex dance between plants and pollinators that is essential for life on earth to continue. With Beverley Glover, Director of the Cambridge University Botanic Garden Jane Memmott, Professor of Ecology at the University of Bristol And Lars Chittka, Professor of Sensory and Behavioural Ecology at Queen Mary, University of London. Producer: Eliane Glaser Reading list: Stephen L Buchmann and Gary Paul Nabhan, The Forgotten Pollinators (Island…

Melvyn Bragg and guests discuss slime mould, a basic organism that grows on logs, cowpats and compost heaps. Scientists have found difficult to categorise slime mould: in 1868, the biologist Thomas Huxley asked: ‘Is this a plant, or is it an animal? Is it both or is it neither?’ and there is a great deal scientists still don’t know about it. But despite not having a brain, slime mould can solve complex problems: it can find the most efficient way round a maze and has been used to map Tokyo’s rail network. Researchers are using it to help find treatments for cancer, Parkinson's and Alzheimer's disease, and computer scientists have designed an algorithm based on slime mould behaviour to learn about dark matter. It’s even been sent to the international space station to help study the effects of weightlessness. With Jonathan Chubb Professor of Quantitative Cell Biology at University College, London Elinor Thompson Reader in microbiology and plant science at the University of Greenwich And Merlin Sheldrake…

Melvyn Bragg and guests discuss some of the great unanswered questions in science: how and where did life on Earth begin, what did it need to thrive and could it be found elsewhere? Charles Darwin speculated that we might look for the cradle of life here in 'some warm little pond'; more recently the focus moved to ocean depths, while new observations in outer space and in laboratories raise fresh questions about the potential for lifeforms to develop and thrive, or 'habitability' as it is termed. What was the chemistry needed for life to begin and is it different from the chemistry we have now? With that in mind, what signs of life should we be looking for in the universe to learn if we are alone? With Jayne Birkby Associate Professor of Exoplanetary Sciences at the University of Oxford and Tutorial Fellow in Physics at Brasenose College Saidul Islam Assistant Professor of Chemistry at Kings College, London And Oliver Shorttle Professor of Natural Philosophy at the University of Cambridge and Fellow of Clare…

Melvyn Bragg and guests discuss the 2000-year-old device which transformed our understanding of astronomy in ancient Greece. In 1900 a group of sponge divers found the wreck of a ship off the coast of the Greek island of Antikythera. Among the items salvaged was a corroded bronze object, the purpose of which was not at first clear. It turned out to be one of the most important discoveries in marine archaeology. Over time, researchers worked out that it was some kind of astronomical analogue computer, the only one to survive from this period as bronze objects were so often melted down for other uses. In recent decades, detailed examination of the Antikythera Mechanism using the latest scientific techniques indicates that it is a particularly intricate tool for showing the positions of planets, the sun and moon, with a complexity and precision not surpassed for over a thousand years. With Mike Edmunds Emeritus Professor of Astrophysics at Cardiff University Jo Marchant Science journalist and author of…

Melvyn Bragg and guests discuss the tantalising idea that there are shortcuts between distant galaxies, somewhere out there in the universe. The idea emerged in the context of Einstein's theories and the challenge has been not so much to prove their unlikely existence as to show why they ought to be impossible. The universe would have to folded back on itself in places, and there would have to be something to make the wormholes and then to keep them open. But is there anywhere in the vast universe like that? Could there be holes that we or more advanced civilisations might travel through, from one galaxy to another and, if not, why not? With Toby Wiseman Professor of Theoretical Physics at Imperial College London Katy Clough Senior Lecturer in Mathematics at Queen Mary, University of London And Andrew Pontzen Professor of Cosmology at Durham University Producer: Simon Tillotson Reading list: Jim Al-Khalili, Black Holes, Wormholes and Time Machines (Taylor & Francis, 1999) Andrew Pontzen, The Universe in a…

Melvyn Bragg and guests discuss the most abundant lifeform on Earth: the viruses that 'eat' bacteria. Early in the 20th century, scientists noticed that something in their Petri dishes was making bacteria disappear and they called these bacteriophages, things that eat bacteria. From studying these phages, it soon became clear that they offered countless real or potential benefits for understanding our world, from the tracking of diseases to helping unlock the secrets of DNA to treatments for long term bacterial infections. With further research, they could be an answer to the growing problem of antibiotic resistance. With Martha Clokie Director for the Centre for Phage Research and Professor of Microbiology at the University of Leicester James Ebdon Professor of Environmental Microbiology at the University of Brighton And Claas Kirchhelle Historian and Chargé de Recherche at the French National Institute of Health and Medical Research’s CERMES3 Unit in Paris. Producer: Simon Tillotson In Our Time is a BBC…

Melvyn Bragg and guests discuss the planet which is closest to our Sun. We see it as an evening or a morning star, close to where the Sun has just set or is about to rise, and observations of Mercury helped Copernicus understand that Earth and the other planets orbit the Sun, so displacing Earth from the centre of our system. In the 20th century, further observations of Mercury helped Einstein prove his general theory of relativity. For the last 50 years we have been sending missions there to reveal something of Mercury's secrets and how those relate to the wider universe, and he latest, BepiColombo, is out there in space now. With Emma Bunce Professor of Planetary Plasma Physics and Director of the Institute for Space at the University of Leicester David Rothery Professor of Planetary Geosciences at the Open University And Carolin Crawford Emeritus Fellow of Emmanuel College, University of Cambridge, and Emeritus Member of the Institute of Astronomy, Cambridge Producer: Simon Tillotson In Our Time is a BBC…

Melvyn Bragg and guests discuss the Serbian-American inventor Nikola Tesla (1856-1943) and his role in the development of electrical systems towards the end of the nineteenth century. He made his name in New York in the contest over which current should flow into homes and factories in America. Some such as Edison backed direct current or DC while others such as Westinghouse backed alternating current or AC and Nikola Tesla’s invention of a motor that worked on AC swung it for the alternating system that went on to power the modern age. He ensured his reputation and ideas burnt brightly for the next decades, making him synonymous with the lone, genius inventor of the new science fiction. With Simon Schaffer Emeritus Fellow of Darwin College, University of Cambridge Jill Jonnes Historian and author of “Empires of Light: Edison, Tesla, Westinghouse and the Race to Electrify the World” And Iwan Morus Professor of History at Aberystwyth University Producer: Simon Tillotson Reading list: W. Bernard Carlson,…

Jupiter is the largest planet in our solar system, and it’s hard to imagine a world more alien and different from Earth. It’s known as a Gas Giant, and its diameter is eleven times the size of Earth’s: our planet would fit inside it one thousand three hundred times. But its mass is only three hundred and twenty times greater, suggesting that although Jupiter is much bigger than Earth, the stuff it’s made of is much, much lighter. When you look at it through a powerful telescope you see a mass of colourful bands and stripes: these are the tops of ferocious weather systems that tear around the planet, including the great Red Spot, probably the longest-lasting storm in the solar system. Jupiter is so enormous that it’s thought to have played an essential role in the distribution of matter as the solar system formed – and it plays an important role in hoovering up astral debris that might otherwise rain down on Earth. It’s almost a mini solar system in its own right, with 95 moons orbiting around it. At least…

Melvyn Bragg and guests discuss some of the chemical signals coursing through our bodies throughout our lives, produced in separate areas and spreading via the bloodstream. We call these 'hormones' and we produce more than 80 of them of which the best known are arguably oestrogen, testosterone, adrenalin, insulin and cortisol. On the whole hormones operate without us being immediately conscious of them as their goal is homeostasis, maintaining the levels of everything in the body as required without us having to think about them first. Their actions are vital for our health and wellbeing and influence many different aspects of the way our bodies work. With Sadaf Farooqi Professor of Metabolism and Medicine at the University of Cambridge Rebecca Reynolds Professor of Metabolic Medicine at the University of Edinburgh And Andrew Bicknell Associate Professor in the School of Biological Sciences at the University of Reading Produced by Victoria Brignell Reading list: Rachel Carson, Silent Spring (first published…

Melvyn Bragg and guests discuss the German physicist who, at the age of 23 and while still a student, effectively created quantum mechanics for which he later won the Nobel Prize. Werner Heisenberg made this breakthrough in a paper in 1925 when, rather than starting with an idea of where atomic particles were at any one time, he worked backwards from what he observed of atoms and their particles and the light they emitted, doing away with the idea of their continuous orbit of the nucleus and replacing this with equations. This was momentous and from this flowed what’s known as his Uncertainty Principle, the idea that, for example, you can accurately measure the position of an atomic particle or its momentum, but not both. With Fay Dowker Professor of Theoretical Physics at Imperial College London Harry Cliff Research Fellow in Particle Physics at the University of Cambridge And Frank Close Professor Emeritus of Theoretical Physics and Fellow Emeritus at Exeter College at the University of Oxford Producer:…

Melvyn Bragg and guests discuss the tiny drifting organisms in the oceans that sustain the food chain for all the lifeforms in the water and so for the billions of people who, in turn, depend on the seas for their diet. In Earth's development, the plant-like ones among them, the phytoplankton, produced so much oxygen through photosynthesis that around half the oxygen we breathe today originated there. And each day as the sun rises, the animal ones, the zooplankton, sink to the depths of the seas to avoid predators in such density that they appear on ship sonars like a new seabed, only to rise again at night in the largest migration of life on this planet. With Carol Robinson Professor of Marine Sciences at the University of East Anglia Abigail McQuatters-Gollop Associate Professor of Marine Conservation at the University of Plymouth And Christopher Lowe Lecturer in Marine Biology at Swansea University Producer: Simon Tillotson Reading list: Juli Berwald, Spineless: The Science of Jellyfish and the Art of…

Melvyn Bragg and guests discuss the man who, in 1905, produced several papers that were to change the world of physics and whose name went on to become a byword for genius. This was Albert Einstein, then still a technical expert at a Swiss patent office, and that year of 1905 became known as his annus mirabilis ('miraculous year'). While Einstein came from outside the academic world, some such as Max Planck championed his theory of special relativity, his principle of mass-energy equivalence that followed, and his explanations of Brownian Motion and the photoelectric effect. Yet it was not until 1919, when a solar eclipse proved his theory that gravity would bend light, that Einstein became an international celebrity and developed into an almost mythical figure. With Richard Staley Professor in History and Philosophy of Science at the University of Cambridge and Professor in History of Science at the University of Copenhagen Diana Kormos Buchwald Robert M. Abbey Professor of History and Director and General…

Melvyn Bragg and guests discuss the power-packs within cells in all complex life on Earth. Inside each cell of every complex organism there are structures known as mitochondria. The 19th century scientists who first observed them thought they were bacteria which had somehow invaded the cells they were studying. We now understand that mitochondria take components from the food we eat and convert them into energy. Mitochondria are essential for complex life, but as the components that run our metabolisms they can also be responsible for a range of diseases – and they probably play a role in how we age. The DNA in mitochondria is only passed down the maternal line. This means it can be used to trace population movements deep into human history, even back to an ancestor we all share: mitochondrial Eve. With Mike Murphy Professor of Mitochondrial Redox Biology at the University of Cambridge Florencia Camus NERC Independent Research Fellow at University College London and Nick Lane Professor of Evolutionary…

Melvyn Bragg and guests discuss the life, ideas and legacy of the pioneering Swedish botanist Carl Linnaeus (1707 – 1778). The philosopher Jean-Jacques Rousseau once wrote: "Tell him I know no greater man on earth". The son of a parson, Linnaeus grew up in an impoverished part of Sweden but managed to gain a place at university. He went on to transform biology by making two major innovations. He devised a simpler method of naming species and he developed a new system for classifying plants and animals, a system that became known as the Linnaean hierarchy. He was also one of the first people to grow a banana in Europe. With Staffan Muller-Wille University Lecturer in History of Life, Human and Earth Sciences at the University of Cambridge Stella Sandford Professor of Modern European Philosophy at Kingston University, London and Steve Jones Senior Research Fellow in Genetics at University College, London Producer Luke Mulhall

Paul Erdős (1913 – 1996) is one of the most celebrated mathematicians of the 20th century. During his long career, he made a number of impressive advances in our understanding of maths and developed whole new fields in the subject. He was born into a Jewish family in Hungary just before the outbreak of World War I, and his life was shaped by the rise of fascism in Europe, anti-Semitism and the Cold War. His reputation for mathematical problem solving is unrivalled and he was extraordinarily prolific. He produced more than 1,500 papers and collaborated with around 500 other academics. He also had an unconventional lifestyle. Instead of having a long-term post at one university, he spent much of his life travelling around visiting other mathematicians, often staying for just a few days. With Colva Roney-Dougal Professor of Pure Mathematics at the University of St Andrews Timothy Gowers Professor of Mathematics at the College de France in Paris and Fellow of Trinity College, Cambridge and Andrew Treglown…

Melvyn Bragg and guests discuss the pioneering Danish astronomer Tycho Brahe (1546 – 1601) whose charts offered an unprecedented level of accuracy. In 1572 Brahe's observations of a new star challenged the idea, inherited from Aristotle, that the heavens were unchanging. He went on to create his own observatory complex on the Danish island of Hven, and there, working before the invention of the telescope, he developed innovative instruments and gathered a team of assistants, taking a highly systematic approach to observation. A second, smaller source of renown was his metal prosthetic nose, which he needed after a serious injury sustained in a duel. The image above shows Brahe aged 40, from the Atlas Major by Johann Blaeu. With Ole Grell Emeritus Professor in Early Modern History at the Open University Adam Mosley Associate Professor of History at Swansea University and Emma Perkins Affiliate Scholar in the Department of History and Philosophy of Science at the University of Cambridge.

Melvyn Bragg and guests discuss the discovery made in 1911 by the Dutch physicist Heike Kamerlingh Onnes (1853-1926). He came to call it Superconductivity and it is a set of physical properties that nobody predicted and that none, since, have fully explained. When he lowered the temperature of mercury close to absolute zero and ran an electrical current through it, Kamerlingh Onnes found not that it had low resistance but that it had no resistance. Later, in addition, it was noticed that a superconductor expels its magnetic field. In the century or more that has followed, superconductors have already been used to make MRI scanners and to speed particles through the Large Hadron Collider and they may perhaps bring nuclear fusion a little closer (a step that could be world changing). The image above is from a photograph taken by Stephen Blundell of a piece of superconductor levitating above a magnet. With Nigel Hussey Professor of Experimental Condensed Matter Physics at the University of Bristol and Radbout…

Melvyn Bragg and guests discuss the voyage of HMS Challenger which set out from Portsmouth in 1872 with a mission a to explore the ocean depths around the world and search for new life. The scale of the enterprise was breath taking and, for its ambition, it has since been compared to the Apollo missions. The team onboard found thousands of new species, proved there was life on the deepest seabeds and plumbed the Mariana Trench five miles below the surface. Thanks to telegraphy and mailboats, its vast discoveries were shared around the world even while Challenger was at sea, and they are still being studied today, offering insights into the ever-changing oceans that cover so much of the globe and into the health of our planet. The image above is from the journal of Pelham Aldrich R.N. who served on the Challenger Surveying Expedition from 1872-5. With Erika Jones Curator of Navigation and Oceanography at Royal Museums Greenwich Sam Robinson Southampton Marine and Maritime Institute Research Fellow at the…

Melvyn Bragg and guests discuss one of the greatest changes in the history of life on Earth. Around 400 million years ago some of our ancestors, the fish, started to become a little more like humans. At the swampy margins between land and water, some fish were turning their fins into limbs, their swim bladders into lungs and developed necks and eventually they became tetrapods, the group to which we and all animals with backbones and limbs belong. After millions of years of this transition, these tetrapod descendants of fish were now ready to leave the water for a new life of walking on land, and with that came an explosion in the diversity of life on Earth. The image above is a representation of Tiktaalik Roseae, a fish with some features of a tetrapod but not one yet, based on a fossil collected in the Canadian Arctic. With Emily Rayfield Professor of Palaeobiology at the University of Bristol Michael Coates Chair and Professor of Organismal Biology and Anatomy at the University of Chicago And Steve…

Melvyn Bragg and guests discuss an atomic particle that's become inseparable from modernity. JJ Thomson discovered the electron 125 years ago, so revealing that atoms, supposedly the smallest things, were made of even smaller things. He pictured them inside an atomic ball like a plum pudding, with others later identifying their place outside the nucleus - and it is their location on the outer limit that has helped scientists learn so much about electrons and with electrons. We can use electrons to reveal the secrets of other particles and, while electricity exists whether we understand electrons or not, the applications of electricity and electrons grow as our knowledge grows. Many questions, though, remain unanswered. With Victoria Martin Professor of Collider Physics at the University of Edinburgh Harry Cliff Research Fellow in Particle Physics at the University of Cambridge And Frank Close Professor Emeritus of Theoretical Physics and Fellow Emeritus at Exeter College at the University of Oxford Producer:…

Melvyn Bragg and guests discuss the abrupt transformation of stars after shining brightly for millions or billions of years, once they lack the fuel to counter the force of gravity. Those like our own star, the Sun, become red giants, expanding outwards and consuming nearby planets, only to collapse into dense white dwarves. The massive stars, up to fifty times the mass of the Sun, burst into supernovas, visible from Earth in daytime, and become incredibly dense neutron stars or black holes. In these moments of collapse, the intense heat and pressure can create all the known elements to form gases and dust which may eventually combine to form new stars, new planets and, as on Earth, new life. The image above is of the supernova remnant Cassiopeia A, approximately 10,000 light years away, from a once massive star that died in a supernova explosion that was first seen from Earth in 1690 With Martin Rees Astronomer Royal, Fellow of Trinity College, Cambridge Carolin Crawford Emeritus Member of the Institute of…

Melvyn Bragg and guests discuss one of our ancestors, Homo erectus, who thrived on Earth for around two million years whereas we, Homo sapiens, emerged only in the last three hundred thousand years. Homo erectus, or Upright Man, spread from Africa to Asia and it was on the Island of Java that fossilised remains were found in 1891 in an expedition led by Dutch scientist Eugène Dubois. Homo erectus people adapted to different habitats, ate varied food, lived in groups, had stamina to outrun their prey; and discoveries have prompted many theories on the relationship between their diet and the size of their brains, on their ability as seafarers, on their creativity and on their ability to speak and otherwise communicate. The image above is from a diorama at the Moesgaard Museum in Denmark, depicting the Turkana Boy referred to in the programme. With Peter Kjærgaard Director of the Natural History Museum of Denmark and Professor of Evolutionary History at the University of Copenhagen José Joordens Senior…

Melvyn Bragg and guests discuss the study of earthquakes. A massive earthquake in 1755 devastated Lisbon, and this disaster helped inspire a new science of seismology which intensified after San Francisco in 1906 and advanced even further with the need to monitor nuclear tests around the world from 1945 onwards. While we now know so much more about what lies beneath the surface of the Earth, and how rocks move and crack, it remains impossible to predict when earthquakes will happen. Thanks to seismology, though, we have a clearer idea of where earthquakes will happen and how to make some of them less hazardous to lives and homes. With Rebecca Bell Senior lecturer in Geology and Geophysics at Imperial College London Zoe Mildon Lecturer in Earth Sciences and Future Leaders Fellow at the University of Plymouth And James Hammond Reader in Geophysics at Birkbeck, University of London Producer: Simon Tillotson

Melvyn Bragg and guests discuss William Herschel (1738 – 1822) and his sister Caroline Herschel (1750 – 1848) who were born in Hanover and made their reputation in Britain. William was one of the most eminent astronomers in British history. Although he started life as a musician, as a young man he became interested in studying the night sky. With an extraordinary talent, he constructed telescopes that were able to see further and more clearly than any others at the time. He is most celebrated today for discovering the planet Uranus and detecting what came to be known as infrared radiation. Caroline also became a distinguished astronomer, discovering several comets and collaborating with her brother. With Monica Grady Professor of Planetary and Space Sciences at the Open University Carolin Crawford Institute of Astronomy, Cambridge and an Emeritus Fellow of Emmanuel College, University of Cambridge And Jim Bennett Keeper Emeritus at the Science Museum in London. Studio producer: John Goudie

Melvyn Bragg and guests discuss the simple animals which informed Charles Darwin's first book, The Structure and Distribution of Coral Reefs, published in 1842. From corals, Darwin concluded that the Earth changed very slowly and was not fashioned by God. Now coral reefs, which some liken to undersea rainforests, are threatened by human activity, including fishing, pollution and climate change. With Steve Jones Senior Research Fellow in Genetics at University College London Nicola Foster Lecturer in Marine Biology at the University of Plymouth And Gareth Williams Associate Professor in Marine Biology at Bangor University School of Ocean Sciences Producer Simon Tilllotson.

Melvyn Bragg and guests discuss the race to build an atom bomb in the USA during World War Two. Before the war, scientists in Germany had discovered the potential of nuclear fission and scientists in Britain soon argued that this could be used to make an atom bomb, against which there could be no defence other than to own one. The fear among the Allies was that, with its head start, Germany might develop the bomb first and, unmatched, use it on its enemies. The USA took up the challenge in a huge engineering project led by General Groves and Robert Oppenheimer and, once the first bomb had been exploded at Los Alamos in July 1945, it appeared inevitable that the next ones would be used against Japan with devastating results. The image above is of Robert Oppenheimer and General Groves examining the remains of one the bases of the steel test tower, at the atomic bomb Trinity Test site, in September 1945. With Bruce Cameron Reed The Charles A. Dana Professor of Physics Emeritus at Alma College, Michigan Cynthia…

Melvyn Bragg and guests discuss the remarkable diversity of the animals that dominated life on land in the Triassic, before the rise of the dinosaurs in the Jurassic, and whose descendants are often described wrongly as 'living fossils'. For tens of millions of years, the ancestors of alligators and Nile crocodiles included some as large as a bus, some running on two legs like a T Rex and some that lived like whales. They survived and rebounded from a series of extinction events but, while the range of habitats of the dinosaur descendants such as birds covers much of the globe, those of the crocodiles have contracted, even if the animals themselves continue to evolve today as quickly as they ever have. With Anjali Goswami Research Leader in Life Sciences and Dean of Postgraduate Education at the Natural History Museum Philip Mannion Lecturer in the Department of Earth Sciences at University College London And Steve Brusatte Professor of Palaeontology and Evolution at the University of Edinburgh Producer…

Melvyn Bragg and guests discuss the search for Longitude while at sea. Following efforts by other maritime nations, the British Government passed the Longitude Act in 1714 to reward anyone who devised reliable means for ships to determine their longitude at sea. Mariners could already calculate how far they were north or south, the Latitude, using the Pole Star, but voyaging across the Atlantic to the Caribbean was much less predictable as navigators could not be sure how far east or west they were, a particular problem when heading for islands. It took fifty years of individual genius and collaboration in Britain and across Europe, among astronomers, clock makers, mathematicians and sailors, for the problem to be resolved. With Rebekah Higgitt Principal Curator of Science at National Museums Scotland Jim Bennett Keeper Emeritus at the Science Museum And Simon Schaffer Professor of History and Philosophy of Science at the University of Cambridge Producer: Simon Tillotson

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'. With Marcus du Sautoy Simonyi Professor for the Public Understanding of Science and Professor of Mathematics at the University of Oxford Timothy Gowers Professor of Mathematics at the College de France And Colva Roney-Dougal Professor of Pure Mathematics at the…

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 Extinction With Jessica Whiteside Associate Professor of Geochemistry in the Department of Ocean and Earth Science at the University of…

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. With Patricia Fara Emeritus Fellow of Clare College, Cambridge David Wootton Anniversary Professor of History at the University of York And Judith Zinsser Professor Emerita of History at Miami University of Ohio and biographer of Emilie du Châtelet. Producer: Simon Tillotson

To celebrate Melvyn Bragg’s 27 years presenting In Our Time, five well-known fans of the programme have chosen their favourite episodes. Guy Garvey, lyricist and lead singer of the band Elbow, has selected the episode on eclipses, first broadcast in December 2020. Solar eclipses are some of life’s most extraordinary moments, when day becomes night and the stars come out before day returns either all too soon or not soon enough, depending on what you understand to be happening. In ancient China, for example, there was a story that a dragon was eating the sun and it had to be scared away by banging pots and pans if the sun were to return. Total lunar eclipses are more frequent and last longer, with a blood moon coloured red like a sunrise or sunset. Both events have created the chance for scientists to learn something remarkable, from the speed of light, to the width of the Atlantic, to the roundness of the Earth, to discovering helium and proving Einstein’s Theory of General Relativity. With Carolin Crawford…

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. With Leslie Ann Goldberg Professor of Computer Science and Fellow of St Edmund Hall, University of Oxford Simon Schaffer Professor of the History of Science at the…

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, Cambridge Valerie Gibson Professor of High Energy Physics at the University of Cambridge and Fellow of Trinity College And David Berman Professor of Theoretical Physics at Queen Mary University of London Producer: 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 Exeter Christine Janis Honorary Professor in Palaeobiology at the University of Bristol and Professor Emerita in Ecology and Evolutionary Biology at Brown University And John Hutchinson Professor in Evolutionary Biomechanics at the Royal Veterinary College Producer: 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 London Helen Mason OBE Reader in Solar Physics at the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Fellow at St Edmund's College And Tim Horbury Professor of Physics at Imperial College London…

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 Museum Nicola Nadeau Lecturer in Evolutionary Biology at the University of Sheffield And Steve Jones Senior Research Fellow in Genetics at University College London Producer: 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 Hodgkin Judith Howard Professor of Chemistry at Durham University and Patricia Fara Fellow of Clare College, Cambridge Producer: Simon Tillotson

Melvyn Bragg and guests discuss how scientists sought to understand the properties of gases and the relationship between pressure and volume, and what that search unlocked. Newton theorised that there were static particles in gases that pushed against each other all the harder when volume decreased, hence the increase in pressure. Those who argued that molecules moved, and hit each other, were discredited until James Maxwell and Ludwig Boltzmann used statistics to support this kinetic theory. Ideas about atoms developed in tandem with this, and it came as a surprise to scientists in C20th that the molecules underpinning the theory actually existed and were not simply thought experiments. The image above is of Ludwig Boltzmann from a lithograph by Rudolf Fenzl, 1898 With Steven Bramwell Professor of Physics at University College London Isobel Falconer Reader in History of Mathematics at the University of St Andrews and Ted Forgan Emeritus Professor of Physics at the University of Birmingham Producer: Simon…

Melvyn Bragg and guests discuss theories about the origins of teeth in vertebrates, and what we can learn from sharks in particular and their ancestors. Great white sharks can produce up to 100,000 teeth in their lifetimes. For humans, it is closer to a mere 50 and most of those have to last from childhood. Looking back half a billion years, though, the ancestors of sharks and humans had no teeth in their mouths at all, nor jaws. They were armoured fish, sucking in their food. The theory is that either their tooth-like scales began to appear in mouths as teeth, or some of their taste buds became harder. If we knew more about that, and why sharks can regenerate their teeth, then we might learn how humans could grow new teeth in later lives. With Gareth Fraser Assistant Professor in Biology at the University of Florida Zerina Johanson Merit Researcher in the Department of Earth Sciences at the Natural History Museum and Philip Donoghue Professor of Palaeobiology at the University of Bristol Producer: Simon…

Melvyn Bragg and guests discuss how members of the same species send each other invisible chemical signals to influence the way they behave. Pheromones are used by species across the animal kingdom in a variety of ways, such as laying trails to be followed, to raise the alarm, to scatter from predators, to signal dominance and to enhance attractiveness and, in honey bees, even direct development into queen or worker. The image above is of male and female ladybirds that have clustered together in response to pheromones. With Tristram Wyatt Senior Research Fellow at the Department of Zoology at the University of Oxford Jane Hurst William Prescott Professor of Animal Science at the University of Liverpool and Francis Ratnieks Professor of Apiculture and Head of the Laboratory of Apiculture and Social Insects at the University of Sussex Producer: Simon Tillotson

Melvyn Bragg and guests discuss the remarkable achievement of Aristotle (384-322BC) in the realm of biological investigation, for which he has been called the originator of the scientific study of life. Known mainly as a philosopher and the tutor for Alexander the Great, who reportedly sent him animal specimens from his conquests, Aristotle examined a wide range of life forms while by the Sea of Marmara and then on the island of Lesbos. Some ideas, such as the the spontaneous generation of flies, did not survive later scrutiny, yet his influence was extraordinary and his work was unequalled until the early modern period. The image above is of the egg and embryo of a dogfish, one of the animals Aristotle described accurately as he recorded their development. With Armand Leroi Professor of Evolutionary Development Biology at Imperial College London Myrto Hatzimichali Lecturer in Classics at the University of Cambridge And Sophia Connell Lecturer in Philosophy at Birkbeck, University of London Producer: Simon…

Melvyn Bragg and guests discuss the ideas and life of one of the greatest mathematicians of the 20th century, Emmy Noether. Noether’s Theorem is regarded as one of the most important mathematical theorems, influencing the evolution of modern physics. Born in 1882 in Bavaria, Noether studied mathematics at a time when women were generally denied the chance to pursue academic careers and, to get round objections, she spent four years lecturing under a male colleague’s name. In the 1930s she faced further objections to her teaching, as she was Jewish, and she left for the USA when the Nazis came to power. Her innovative ideas were to become widely recognised and she is now considered to be one of the founders of modern algebra. With Colva Roney Dougal Professor of Pure Mathematics at the University of St Andrews David Berman Professor in Theoretical Physics at Queen Mary, University of London Elizabeth Mansfield Professor of Mathematics at the University of Kent Producer: Simon Tillotson

Melvyn Bragg and guests discuss the planet Venus which is both the morning star and the evening star, rotates backwards at walking speed and has a day which is longer than its year. It has long been called Earth’s twin, yet the differences are more striking than the similarities. Once imagined covered with steaming jungles and oceans, we now know the surface of Venus is 450 degrees celsius, and the pressure there is 90 times greater than on Earth, enough to crush an astronaut. The more we learn of it, though, the more we learn of our own planet, such as whether Earth could become more like Venus in some ways, over time. With Carolin Crawford Public Astronomer at the Institute of Astronomy and Fellow of Emmanuel College, University of Cambridge Colin Wilson Senior Research Fellow in Planetary Science at the University of Oxford And Andrew Coates Professor of Physics at Mullard Space Science Laboratory, University College London Produced by: Simon Tillotson and Julia Johnson

Melvyn Bragg and guests discuss the properties of atoms or molecules with a single unpaired electron, which tend to be more reactive, keen to seize an electron to make it a pair. In the atmosphere, they are linked to reactions such as rusting. Free radicals came to prominence in the 1950s with the discovery that radiation poisoning operates through free radicals, as it splits water molecules and produces a very reactive hydroxyl radical which damages DNA and other molecules in the cell. There is also an argument that free radicals are a byproduct of normal respiration and over time they cause an accumulation of damage that is effectively the process of ageing. For all their negative associations, free radicals play an important role in signalling and are also linked with driving cell division, both cancer and normal cell division, even if they tend to become damaging when there are too many of them. With Nick Lane Professor of Evolutionary Biochemistry at University College London Anna Croft Associate…

Melvyn Bragg and guests discuss the history of real and imagined machines that appear to be living, and the questions they raise about life and creation. Even in myth they are made by humans, not born. The classical Greeks built some and designed others, but the knowledge of how to make automata and the principles behind them was lost in the Latin Christian West, remaining in the Greek-speaking and Arabic-speaking world. Western travellers to those regions struggled to explain what they saw, attributing magical powers. The advance of clockwork raised further questions about what was distinctly human, prompting Hobbes to argue that humans were sophisticated machines, an argument explored in the Enlightenment and beyond. The image above is Jacques de Vaucanson's mechanical duck (1739), which picked up grain, digested and expelled it. If it looks like a duck... with Simon Schaffer Professor of History of Science at Cambridge University Elly Truitt Associate Professor of Medieval History at Bryn Mawr College And…