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In Our Time: Science

<p>Scientific principles, theory, and the role of key figures in the advancement of science.</p>

BBC Radio 4

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 AustraliaJon Copley
Professor of Ocean Exploration and Science Communication at the University of SouthamptonAnd Alan Jamieson
Director of the Deep Sea Research Centre at the University of Western AustraliaProducer: Simon TillotsonReading 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, 2023)Hali Felt, Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor (Henry Holt & Co, 2012)M.E. Gerringer, ‘Pseudoliparis swirei: A newly-discovered hadal liparid (Scorpaeniformes: Liparidae) from the Mariana Trench’ (Zootaxa 4358 (1), 161-177, 2017)A.J. Jamieson, The Hadal Zone: Life in the Deepest Oceans (Cambridge University Press, 2015)A.J. Jamieson et al., ‘A global assessment of fishes at lower abyssal and upper hadal depths (5000 to 8000 m)’ (Deep-Sea Research Part 1. 178: 103642, 2021)A.J. Jamieson et al., ‘Fear and loathing of the deep ocean: Why don’t people care about the deep sea?’ (ICES Journal of Marine Science. 78: 797-809, 2020)A.J. Jamieson et al., ‘Microplastic and synthetic fibers ingested by deep-sea amphipods in six of the deepest marine environments on Earth’ (Royal Society Open Science, 6, 180667, 2019)A.J. Jamieson et al., ‘Bioaccumulation of persistent organic pollutants in the deepest ocean fauna’ (Nature Ecology and Evolution. 1, 0051, 2017)V.L. Vescovo et al., ‘Safety and conservation at the deepest place on Earth: A call for prohibiting the deliberate discarding of nondegradable umbilicals from deep-sea exploration vehicles’ (Marine Policy. 128, 104463, 2021)J.N.J. Weston et al., ‘New species of Eurythenes from hadal depths of the Mariana Trench, Pacific Ocean (Crustacea: Amphipoda)’ (Zootaxa. 4748(1): 163-181, 2020)In Our Time is a BBC Studios ProductionSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Misha Glenny and expert guests explore the characters, events and discoveries that have shaped our world.

The Mariana Trench

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 EdinburghEmily Rayfield
Professor of Palaeobiology at the University of BristolAndJonathan Codd
Professor of Integrative Zoology at the University of ManchesterProducer: Simon Tillotson Reading list:Roger B. J. Benson, Richard J. Butler, Matthew T. Carrano and Patrick M. O'Connor, ‘Air-filled postcranial bones in theropod dinosaurs: physiological implications and the ‘reptile’–bird transition’ (Biological Reviews: Cambridge Philosophical Society, July 2011)Steve Brusatte, The Rise and Fall of the Dinosaurs: A New History of a Lost World (Mariner Books, 2018)Jennifer A. Clack, Gaining Ground: The Origin and Evolution of Tetrapods (2nd edition, Indiana University Press, 2012)Camila Cupello et al, ‘Lung Evolution in vertebrates and the water-to-land transition’ (eLife, July 2022)Andrew Davies and Carl Moore, The Respiratory System (Elsevier, 2010) Kenneth Kardong, Vertebrates: Comparative Anatomy, Function, Evolution (8th edition, McGraw-Hill Education, 2018)Ye Li et al, ‘Origin and stepwise evolution of vertebrate lungs’ (Nature Ecology & Evolution, Feb 2025)   P. Martin Sander and Marcus Clauss, ‘Sauropod Gigantism’ (Science, Oct 2008)Goran Nilsson, Respiratory Physiology of Vertebrates: Life With and Without Oxygen (Cambridge University Press, 2010)Steven F. Perry et al, ‘What came first, the lung or the breath?’ (Comparative Biochemistry and Physiology, Part A: Molecular & Integrative Biology, May 2001)Michael J. Stephen, Breath Taking: The Power, Fragility, and Future of Our Extraordinary Lungs (Grove/Atlantic, 2022)Mathew J. Wedel, ‘The evolution of vertebral pneumaticity in sauropod dinosaurs’ (Journal of Vertebrate Paleontology, Aug 2010)In Our Time is a BBC Studios Audio ProductionSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the characters, events and discoveries that have shaped our world.

The Evolution of Lungs

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.WithJess Wade
A Royal Society University Research Fellow and Lecturer in Functional Materials at Imperial College, LondonFrank Close
Professor Emeritus of Theoretical Physics and Fellow Emeritus at Exeter College, University of OxfordAnd Steven Bramwell
Director of the London Centre for Nanotechnology and Professor of Physics at University College LondonProducer: Simon TillotsonReading list:Frank Close, Destroyer of Worlds: The Deep History of the Nuclear Age, 1895-1965 (Allen Lane, 2025)Ruth Lewin Sime, Lise Meitner: A Life in Physics (University of California Press, 1996)Marissa Moss, The Woman Who Split the Atom: The Life of Lise Meitner (Abrams Books, 2022)Patricia Rife, Lise Meitner and the Dawn of the Nuclear Age (Birkhauser Verlag, 1999) In Our Time is a BBC Studios Audio Production

Lise Meitner

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 GardenJane Memmott, Professor of Ecology at the University of BristolAndLars Chittka, Professor of Sensory and Behavioural Ecology at Queen Mary, University of London.Producer: Eliane GlaserReading list:Stephen L Buchmann and Gary Paul Nabhan, The Forgotten Pollinators (Island Press, 1997)Lars Chittka, The Mind of a Bee (Princeton University Press, 2023)Steven Falk, Field Guide to the Bees of Britain and Ireland (British Wildlife Publishing, 2015)Francis S. Gilbert (illustrated by Steven J. Falk), Hoverflies: Naturalists' Handbooks vol. 5 (Pelagic Publishing, 2015)Dave Goulson, A Sting in the Tale: My Adventures with Bumblebees (Vintage, 2014)Edwige Moyroud and Beverley J. Glover, ‘The evolution of diverse floral morphologies’ (Current Biology vol 11, 2017)Jeff Ollerton, Birds and Flowers: An Intimate 50 Million Year Relationship (Pelagic Publishing, 2024)
 
Alan E. Stubbs and Steven J. Falk, British Hoverflies (‎British Entomological & Natural History Society, 2002)Timothy Walker, Pollination: The Enduring Relationship Between Plant and Pollinator (Princeton University Press, 2020)In Our Time is a BBC Studios Audio Production

Pollination

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.
 
WithJonathan Chubb
Professor of Quantitative Cell Biology at University College, LondonElinor Thompson
Reader in microbiology and plant science at the University of GreenwichAndMerlin Sheldrake
Biologist and writerProducer: Eliane Glaser In Our Time is a BBC Studios Audio production

Slime Moulds

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 CollegeSaidul Islam
Assistant Professor of Chemistry at Kings College, LondonAnd Oliver Shorttle
Professor of Natural Philosophy at the University of Cambridge and Fellow of Clare CollegeProducer: Simon TillotsonReading list: David Grinspoon, Venus Revealed: A New Look Below the Clouds of Our Mysterious Twin Planet (Basic Books, 1998)Lisa Kaltenegger, Alien Earths: Planet Hunting in the Cosmos (Allen Lane, 2024)Andrew H. Knoll, Life on a Young Planet: The First Three Billion Years of Evolution on Earth (‎Princeton University Press, 2004)Charles H. Langmuir and Wallace Broecker, How to Build a Habitable Planet: The Story of Earth from the Big Bang to Humankind (Princeton University Press, 2012)Joshua Winn, The Little Book of Exoplanets (Princeton University Press, 2023)In Our Time is a BBC Studios Audio Production

The Habitability of Planets

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 UniversityJo Marchant 
Science journalist and author of 'Decoding the Heavens' on the Antikythera MechanismAnd Liba Taub 
Professor Emerita in the Department of History and Philosophy of Science at the University of Cambridge and Visiting Scholar at the Deutsches Museum, MunichProducer: Simon Tillotson
In Our Time is a BBC Studios Audio ProductionReading list:Derek de Solla Price, Gears from the Greeks: The Antikythera Mechanism (American Philosophical Society Press, 1974)M. G. Edmunds, ‘The Antikythera mechanism and the mechanical universe’ (Contemp. Phys. 55, 2014) M.G. Edmunds, ’The Mechanical Universe’ (Astronomy & Geophysics, 64, 2023)James Evans and J. Lennart Berggren, Geminos's Introduction to the Phenomena: A Translation and Study of a Hellenistic Survey of Astronomy (Princeton University Press, 2006)T. Freeth et al., ‘Calendars with Olympiad display and eclipse prediction on the Antikythera mechanism’ (Nature 454, 2008)Alexander Jones, A Portable Cosmos: Revealing the Antikythera Mechanism, Scientific Wonder of the Ancient World (Oxford University Press, 2017)Jo Marchant, Decoding the Heavens: Solving the Mystery of the World’s First Computer (Windmill Books, 2009)J.H. Seiradakis and M.G. Edmunds, ‘Our current knowledge of the Antikythera Mechanism’ (Nature Astronomy 2, 2018)Liba Taub, Ancient Greek and Roman Science: A Very Short Introduction (Oxford University Press, 2022)

The Antikythera Mechanism

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 LondonKaty Clough 
Senior Lecturer in Mathematics at Queen Mary, University of LondonAnd Andrew Pontzen 
Professor of Cosmology at Durham UniversityProducer: Simon TillotsonReading list:Jim Al-Khalili, Black Holes, Wormholes and Time Machines (Taylor & Francis, 1999)Andrew Pontzen, The Universe in a Box: Simulations and the Quest to Code the Cosmos (Riverhead Books, 2023)Claudia de Rham, The Beauty of Falling: A Life in Pursuit of Gravity (Princeton University Press, 2024)Carl Sagan, Contact (Simon and Schuster, 1985)Kip Thorne, Black Holes & Time Warps: Einstein's Outrageous Legacy (W. W. Norton & Company, 1994)Kip Thorne, Science of Interstellar (W. W. Norton & Company, 2014)Matt Visser, Lorentzian Wormholes: From Einstein to Hawking (American Institute of Physics Melville, NY, 1996)
 In Our Time is a BBC Studios Audio Production

Wormholes

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 LeicesterJames Ebdon
Professor of Environmental Microbiology at the University of BrightonAnd Claas Kirchhelle
Historian and Chargé de Recherche at the French National Institute of Health and Medical Research’s CERMES3 Unit in Paris.Producer: Simon TillotsonIn Our Time is a BBC Studios Audio ProductionReading list: James Ebdon, ‘Tackling sources of contamination in water: The age of phage’ (Microbiologist, Society for Applied Microbiology, Vol 20.1, 2022) Thomas Häusler, Viruses vs. Superbugs: A Solution to the Antibiotics Crisis? (Palgrave Macmillan, 2006)Tom Ireland, The Good Virus: The Untold Story of Phages: The Mysterious Microbes that Rule Our World, Shape Our Health and Can Save Our Future (Hodder Press, 2024)Claas Kirchhelle and Charlotte Kirchhelle, ‘Northern Normal–Laboratory Networks, Microbial Culture Collections, and Taxonomies of Power (1939-2000)’ (SocArXiv Papers, 2024) Dmitriy Myelnikov, ‘An alternative cure: the adoption and survival of bacteriophage therapy in the USSR, 1922–1955’ (Journal of the History of Medicine and Allied Sciences 73, no. 4, 2018)Forest Rohwer, Merry Youle, Heather Maughan and Nao Hisakawa, Life in our Phage World: A Centennial Field Guide to Earth’s most Diverse Inhabitants (Wholon, 2014)Steffanie Strathdee and Thomas Patterson (2019) The Perfect Predator: A Scientist’s Race to Save Her Husband from a Deadly Superbug: A Memoir (Hachette Books, 2020)William C. Summers, Félix d`Herelle and the Origins of Molecular Biology (Yale University Press, 1999)William C. Summers, The American Phage Group: Founders of Molecular Biology (University Press, 2023)

Bacteriophages

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. WithEmma Bunce
Professor of Planetary Plasma Physics and Director of the Institute for Space at the University of LeicesterDavid Rothery
Professor of Planetary Geosciences at the Open UniversityAnd Carolin Crawford
Emeritus Fellow of Emmanuel College, University of Cambridge, and Emeritus Member of the Institute of Astronomy, CambridgeProducer: Simon Tillotson
In Our Time is a BBC Studios Audio productionReading list: Emma Bunce, ‘All (X-ray) eyes on Mercury’ (Astronomy & Geophysics, Volume 64, Issue 4, August 2023)  Emma Bunce et al, ‘The BepiColombo Mercury Imaging X-Ray Spectrometer: Science Goals, Instrument Performance and Operations’ (Space Science Reviews: SpringerLink, volume 216, article number 126, Nov 2020)David A. Rothery, Planet Mercury: From Pale Pink Dot to Dynamic World (Springer, 2014)

Mercury

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 CambridgeJill 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 UniversityProducer: Simon TillotsonReading list: W. Bernard Carlson, Tesla: Inventor of the Electrical Age (Princeton University Press, 2013)Margaret Cheney and Robert Uth, Tesla: Master of Lightning (Barnes & Noble Books, 1999) Thomas P. Hughes, Networks of Power: Electrification in Western Society, 1880-1930 (Johns Hopkins University Press, 1983)Carolyn Marvin, When Old Technologies Were New (Open University Press, 1988)Iwan Rhys Morus, Nikola Tesla and the Electrical Future (Icon Books, 2019)Iwan Rhys Morus, How The Victorians Took Us To The Moon (Icon, 2022)David E. Nye, Electrifying America: Social Meanings of a New Technology (MIT Press, 1991)John J. O’Neill, Prodigal Genius: The Life of Nikola Tesla (first published 1944; Cosimo Classics, 2006)Marc J. Seifer, Wizard: The Life and Times of Nikola Tesla, Biography of a Genius (first published 1996; Citadel Press, 2016)Nikola Tesla, My Inventions: The Autobiography of Nikola Tesla (first published 1919; Martino Fine Books, 2011)Nikola Tesla, My Inventions and other Writings (Penguin, 2012)In Our Time is a BBC Studios Audio production

Nikola Tesla

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 LondonHarry Cliff
Research Fellow in Particle Physics at the University of CambridgeAnd Frank Close
Professor Emeritus of Theoretical Physics and Fellow Emeritus at Exeter College at the University of OxfordProducer: Simon TillotsonReading list:Philip Ball, Beyond Weird: Why Everything You Thought You Knew about Quantum Physics Is Different (Vintage, 2018)John Bell, ‘Against 'measurement'’ (Physics World, Vol 3, No 8, 1990)Mara Beller, Quantum Dialogue: The Making of a Revolution (University of Chicago Press, 2001)David C. Cassidy, Beyond Uncertainty: Heisenberg, Quantum Physics, And The Bomb (Bellevue Literary Press, 2010) Werner Heisenberg, Physics and Philosophy (first published 1958; Penguin Classics, 2000)Carlo Rovelli, Helgoland: The Strange and Beautiful Story of Quantum Physics (Penguin, 2022)

Heisenberg's Uncertainty Principle

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.WithSadaf Farooqi
Professor of Metabolism and Medicine at the University of CambridgeRebecca Reynolds
Professor of Metabolic Medicine at the University of EdinburghAndAndrew Bicknell
Associate Professor in the School of Biological Sciences at the University of ReadingProduced by Victoria BrignellReading list:Rachel Carson, Silent Spring (first published 1962; Penguin Classics, 2000)Stephen Nussey and Saffron Whitehead, Endocrinology: An Integrated Approach (BIOS Scientific Publishers; 2001)Aylinr Y. Yilmaz, Comprehensive Introduction to Endocrinology for Novices (Independently published, 2023)

Hormones

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.WithCarol Robinson
Professor of Marine Sciences at the University of East AngliaAbigail McQuatters-Gollop
Associate Professor of Marine Conservation at the University of PlymouthAndChristopher Lowe
Lecturer in Marine Biology at Swansea UniversityProducer: Simon TillotsonReading list: Juli Berwald, Spineless: The Science of Jellyfish and the Art of Growing a Backbone (Riverhead Books, 2018)Sir Alister Hardy, The Open Sea: The World of Plankton (first published 1959; Collins New Naturalist Library, 2009) Richard Kirby, Ocean Drifters: A Secret World Beneath the Waves (Studio Cactus Ltd, 2010)Robert Kunzig, Mapping the Deep: The Extraordinary Story of Ocean Science (Sort Of Books, 2000)Christian Sardet, Plankton: Wonders of the Drifting World (University of Chicago Press, 2015) Helen Scales, The Brilliant Abyss: True Tales of Exploring the Deep Sea, Discovering Hidden Life and Selling the Seabed (Bloomsbury Sigma, 2022)

Plankton

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 CopenhagenDiana Kormos Buchwald
Robert M. Abbey Professor of History and Director and General Editor of The Einstein Papers Project at the California Institute of TechnologyAndJohn Heilbron 
Professor Emeritus at the University of California, BerkeleyProducer: Simon TillotsonReading list: Ronald W. Clark, Einstein: The Life and Times (first published 1971; HarperPaperbacks, 2011)Albert Einstein (eds. Jurgen Renn and Hanoch Gutfreund), Relativity: The Special and the General Theory - 100th Anniversary Edition (Princeton University Press, 2019)Albert Einstein, Out of My Later Years (first published 1950; Citadel Press, 1974)Albert Einstein (ed. Paul A. Schilpp), Albert Einstein: Philosopher-Scientist: The Library of Living Philosophers Volume VII (first published 1949; Open Court, 1970)Albert Einstein (eds. Otto Nathan and Heinz Norden), Einstein on Peace (first published 1981; Literary Licensing, 2011)Albrecht Folsing, Albert Einstein: A Biography (Viking, 1997)J. L. Heilbron, Niels Bohr: A Very Short Introduction (Oxford University Press, 2020)Walter Isaacson, Einstein: His Life and Universe (Simon & Schuster, 2008)Max Jammer, Einstein and Religion (Princeton University Press, 2002)Michel Janssen and Christoph Lehner (eds.), The Cambridge Companion to Einstein (Cambridge University Press, 2014)Dennis Overbye, Einstein in Love: A Scientific Romance (Viking, 2000)Abraham Pais, Subtle Is the Lord: The Science and the Life of Albert Einstein (Oxford University Press, 1982)David E. Rowe and Robert Schulmann (eds.), Einstein on Politics: His Private Thoughts and Public Stands on Nationalism, Zionism, War, Peace, and the Bomb (Princeton University Press, 2007)Matthew Stanley, Einstein's War: How Relativity Triumphed Amid the Vicious Nationalism of World War I (Dutton, 2019)Fritz Stern, Einstein’s German World (Princeton University Press, 1999)A. Douglas Stone, Einstein and the Quantum: The Quest of the Valiant Swabian (Princeton University Press, 2013)Milena Wazeck (trans. Geoffrey S. Koby), Einstein's Opponents: The Public Controversy About the Theory of Relativity in the 1920s (Cambridge University Press, 2014)

Albert Einstein

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 two of these are places life might possibly be found.  WithMichele Dougherty, Professor of Space Physics and Head of the Department of Physics at Imperial College London, and principle investigator of the magnetometer instrument on the JUICE spacecraft (JUICE is the Jupiter Icy Moons Explorer, a mission launched by the European Space Agency in April 2023)Leigh Fletcher, Professor of Planetary Science at the University of Leicester, and interdisciplinary scientist for JUICECarolin Crawford, Emeritus Fellow of Emmanuel College, University of Cambridge, and Emeritus Member of the Institute of Astronomy, Cambridge

Jupiter

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 CambridgeFlorencia Camus 
NERC Independent Research Fellow at University College Londonand Nick Lane
Professor of Evolutionary Biochemistry at University College LondonProducer  Luke Mulhall

Mitochondria

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. WithStaffan Muller-Wille
University Lecturer in History of Life, Human and Earth Sciences at the University of CambridgeStella Sandford
Professor of Modern European Philosophy at Kingston University, Londonand Steve Jones 
Senior Research Fellow in Genetics at University College, LondonProducer  Luke Mulhall

Linnaeus

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 AndrewsTimothy Gowers
Professor of Mathematics at the College de France in Paris and Fellow of Trinity College, CambridgeandAndrew Treglown
Associate Professor in Mathematics at the University of BirminghamThe image above shows a graph occurring in Ramsey Theory. It was created by Dr Katherine Staden, lecturer in the School of Mathematics at the Open University.

Paul Erdős

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.

Tycho Brahe

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 UniversitySuchitra Sebastian
Professor of Physics at the Cavendish Laboratory at the University of CambridgeAndStephen Blundell
Professor of Physics at the University of Oxford and Fellow of Mansfield CollegeProducer: Simon Tillotson

Superconductivity

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.WithErika Jones
Curator of Navigation and Oceanography at Royal Museums GreenwichSam Robinson
Southampton Marine and Maritime Institute Research Fellow at the University of SouthamptonAndGiles Miller
Principal Curator of Micropalaeontology at the Natural History Museum LondonProducer: Simon Tillotson

The Challenger Expedition 1872-1876

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.WithEmily Rayfield
Professor of Palaeobiology at the University of BristolMichael Coates
Chair and Professor of Organismal Biology and Anatomy at the University of ChicagoAnd Steve Brusatte
Professor of Palaeontology and Evolution at the University of EdinburghProducer: Simon Tillotson

The Fish-Tetrapod Transition

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 EdinburghHarry Cliff
Research Fellow in Particle Physics at the University of CambridgeAndFrank Close
Professor Emeritus of Theoretical Physics and Fellow Emeritus at Exeter College at the University of OxfordProducer: Simon Tillotson

The Electron

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 1690WithMartin Rees
Astronomer Royal, Fellow of Trinity College, CambridgeCarolin Crawford
Emeritus Member of the Institute of Astronomy and Emeritus Fellow of Emmanuel College, University of CambridgeAndMark Sullivan
Professor of Astrophysics at the University of SouthamptonProducer: Simon Tillotson

The Death of Stars

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 CopenhagenJosé Joordens
Senior Researcher in Human Evolution at Naturalis Biodiversity Centre and Professor of Human Evolution at Maastricht UniversityAndMark Maslin
Professor of Earth System Science at University College LondonProducer: Simon Tillotson

Homo erectus

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.WithRebecca Bell
Senior lecturer in Geology and Geophysics at Imperial College LondonZoe Mildon
Lecturer in Earth Sciences and Future Leaders Fellow at the University of PlymouthAnd James Hammond
Reader in Geophysics at Birkbeck, University of LondonProducer: Simon Tillotson

Seismology

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.WithMonica Grady
Professor of Planetary and Space Sciences at the Open UniversityCarolin Crawford
Institute of Astronomy, Cambridge and an Emeritus Fellow of Emmanuel College, University of CambridgeAndJim Bennett
Keeper Emeritus at the Science Museum in London.Studio producer: John Goudie

William and Caroline Herschel

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. WithSteve Jones 
Senior Research Fellow in Genetics at University College LondonNicola Foster 
Lecturer in Marine Biology at the University of Plymouth AndGareth Williams 
Associate Professor in Marine Biology at Bangor University School of Ocean SciencesProducer  Simon Tilllotson.

Corals

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.WithBruce Cameron Reed
The Charles A. Dana Professor of Physics Emeritus at Alma College, MichiganCynthia Kelly
Founder and President of the Atomic Heritage FoundationAndFrank Close
Emeritus Professor of Theoretical Physics at the University of Oxford and a Fellow of Exeter College, OxfordProducer: Simon Tillotson

The Manhattan Project

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.WithAnjali Goswami
Research Leader in Life Sciences and Dean of Postgraduate Education at the Natural History MuseumPhilip Mannion
Lecturer in the Department of Earth Sciences at University College London AndSteve Brusatte
Professor of Palaeontology and Evolution at the University of EdinburghProducer Simon Tillotson

The Evolution of Crocodiles

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.WithRebekah Higgitt
Principal Curator of Science at National Museums ScotlandJim Bennett
Keeper Emeritus at the Science MuseumAnd Simon Schaffer
Professor of History and Philosophy of Science at the University of CambridgeProducer: Simon Tillotson

Longitude

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

Pierre-Simon Laplace

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.

The Late Devonian Extinction

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

Emilie du Châtelet

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
Public Astronomer based at the Institute of Astronomy, University of Cambridge and a fellow of Emmanuel CollegeFrank Close
Emeritus Professor of Physics at the University of OxfordAndLucie Green
Professor of Physics and a Royal Society University Research Fellow at Mullard Space Science Laboratory at University College LondonProducers: Simon Tillotson and Julia JohnsonSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the people, ideas, events and discoveries that have shaped our world. In Our Time is a BBC Studios production

Eclipses

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

Alan Turing

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

Paul Dirac

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

The Evolution of Horses

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

Solar Wind

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

Hybrids

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

Dorothy Hodgkin

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, 1898With Steven Bramwell
Professor of Physics at University College LondonIsobel Falconer
Reader in History of Mathematics at the University of St Andrewsand Ted Forgan
Emeritus Professor of Physics at the University of BirminghamProducer: Simon Tillotson

Kinetic Theory

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 FloridaZerina Johanson
Merit Researcher in the Department of Earth Sciences at the Natural History Museumand Philip Donoghue
Professor of Palaeobiology at the University of BristolProducer: Simon Tillotson

The Evolution of Teeth

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 OxfordJane Hurst
William Prescott Professor of Animal Science at the University of Liverpooland Francis Ratnieks
Professor of Apiculture and Head of the Laboratory of Apiculture and Social Insects at the University of SussexProducer: Simon Tillotson

Pheromones

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.WithArmand Leroi
Professor of Evolutionary Development Biology at Imperial College LondonMyrto Hatzimichali
Lecturer in Classics at the University of CambridgeAndSophia Connell
Lecturer in Philosophy at Birkbeck, University of LondonProducer: Simon Tillotson

Aristotle's Biology

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 AndrewsDavid Berman
Professor in Theoretical Physics at Queen Mary, University of LondonElizabeth Mansfield   
Professor of Mathematics at the University of Kent Producer: Simon Tillotson

Emmy Noether

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. WithCarolin Crawford
Public Astronomer at the Institute of Astronomy and Fellow of Emmanuel College, University of CambridgeColin Wilson
Senior Research Fellow in Planetary Science at the University of OxfordAnd Andrew Coates
Professor of Physics at Mullard Space Science Laboratory, University College LondonProduced by: Simon Tillotson and Julia Johnson

Venus

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 LondonAnna Croft
Associate Professor at the Department of Chemical and Environmental Engineering at the University of NottinghamAnd Mike Murphy
Professor of Mitochondrial Redox Biology at Cambridge UniversityProducer: Simon Tillotson

Free Radicals

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 UniversityElly Truitt
Associate Professor of Medieval History at Bryn Mawr CollegeAnd Franziska Kohlt
Doctoral Researcher in English Literature and the History of Science at the University of OxfordProducer: Simon Tillotson

Automata

Melvyn Bragg and guests discuss how some bats, dolphins and other animals emit sounds at high frequencies to explore their environments, rather than sight. This was such an unlikely possibility, to natural historians from C18th onwards, that discoveries were met with disbelief even into the C20th; it was assumed that bats found their way in the dark by touch. Not all bats use echolocation, but those that do have a range of frequencies for different purposes and techniques for preventing themselves becoming deafened by their own sounds. Some prey have evolved ways of detecting when bats are emitting high frequencies in their direction, and some fish have adapted to detect the sounds dolphins use to find them. With Kate Jones
Professor of Ecology and Biodiversity at University College LondonGareth Jones
Professor of Biological Sciences at the University of BristolAndDean Waters
Lecturer in the Environment Department at the University of YorkProducer: Simon Tillotson.

Echolocation

Melvyn Bragg and guests discuss the discovery and growing understanding of the Proton, formed from three quarks close to the Big Bang and found in the nuclei of all elements. The positive charges they emit means they attract the fundamental particles of negatively charged electrons, an attraction that leads to the creation of atoms which in turn leads to chemistry, biology and life itself. The Sun (in common with other stars) is a fusion engine that turn protons by a series of processes into helium, emitting energy in the process, with about half of the Sun's protons captured so far. Hydrogen atoms, stripped of electrons, are single protons which can be accelerated to smash other nuclei and have applications in proton therapy. Many questions remain, such as why are electrical charges for protons and electrons so perfectly balanced?WithFrank Close
Professor Emeritus of Physics at the University of OxfordHelen Heath
Reader in Physics at the University of BristolAndSimon Jolly
Lecturer in High Energy Physics at University College LondonProducer: Simon Tillotson.

The Proton

In a programme first broadcast on April 12th 2018, Melvyn Bragg and guests discuss the contribution of George Stephenson (1781-1848) and his son Robert (1803-59) to the development of the railways in C19th. George became known as The Father of Railways and yet arguably Robert's contribution was even greater, with his engineering work going far beyond their collaboration. Robert is credited with the main role in the design of their locomotives. George had worked on stationary colliery steam engines and, with Robert, developed the moving steam engine Locomotion No1 for the Stockton and Darlington Railway in 1825. They produced the Rocket for the Rainhill Trials on the Liverpool and Manchester Railway in 1829. From there, the success of their designs and engineering led to the expansion of railways across Britain and around the world. with Dr Michael Bailey
Railway historian and editor of the most recent biography of Robert StephensonJulia Elton
Past President of the Newcomen Society for the History of Engineering and TechnologyandColin Divall
Professor Emeritus of Railway Studies at the University of YorkProducer: Simon Tillotson.
This programme is a repeat

George and Robert Stephenson

Melvyn Bragg and guests discuss the pioneering scientist Rosalind Franklin (1920 - 1958). During her distinguished career, Franklin carried out ground-breaking research into coal and viruses but she is perhaps best remembered for her investigations in the field of DNA. In 1952 her research generated a famous image that became known as Photograph 51. When the Cambridge scientists Francis Crick and James Watson saw this image, it enabled them the following year to work out that DNA has a double-helix structure, one of the most important discoveries of modern science. Watson, Crick and Franklin's colleague Maurice Wilkins received a Nobel Prize in 1962 for this achievement but Franklin did not and today many people believe that Franklin has not received enough recognition for her work. With:Patricia Fara
President of the British Society for the History of ScienceJim Naismith
Interim lead of the Rosalind Franklin Institute, Director of the Research Complex at Harwell and Professor at the University of OxfordJudith Howard 
Professor of Chemistry at Durham UniversityProducer: Victoria Brignell.

Rosalind Franklin

Melvyn Bragg and guests discuss fungi. These organisms are not plants or animals but a kingdom of their own. Millions of species of fungi live on the Earth and they play a crucial role in ecosystems, enabling plants to obtain nutrients and causing material to decay. Without fungi, life as we know it simply would not exist. They are also a significant part of our daily life, making possible the production of bread, wine and certain antibiotics. Although fungi brought about the colonisation of the planet by plants about 450 million years ago, some species can kill humans and devastate trees. With:Lynne Boddy
Professor of Fungal Ecology at Cardiff UniversitySarah Gurr
Professor of Food Security in the Biosciences Department at the University of ExeterDavid Johnson
N8 Chair in Microbial Ecology at the University of ManchesterProducer: Victoria Brignell.

Fungi

The octopus, the squid, the nautilus and the cuttlefish are some of the most extraordinary creatures on this planet, intelligent and yet apparently unlike other life forms. They are cephalopods and are part of the mollusc family like snails and clams, and they have some characteristics in common with those. What sets them apart is the way members of their group can change colour, camouflage themselves, recognise people, solve problems, squirt ink, power themselves with jet propulsion and survive both on land, briefly, and in the deepest, coldest oceans. And, without bones or shells, they grow so rapidly they can outstrip their rivals when habitats change, making them the great survivors and adaptors of the animal world.WithLouise Allcock
Lecturer in Zoology at the National University of Ireland, GalwayPaul Rodhouse
Emeritus Fellow of the British Antarctic SurveyandJonathan Ablett
Senior Curator of Molluscs at the Natural History MuseumProducer: Simon Tillotson.

Cephalopods

In a programme first broadcast in 2017, Melvyn Bragg and guests discuss Gauss (1777-1855), widely viewed as one of the greatest mathematicians of all time. He was a child prodigy, correcting his father's accounts before he was 3, dumbfounding his teachers with the speed of his mental arithmetic, and gaining a wealthy patron who supported his education. He wrote on number theory when he was 21, with his Disquisitiones Arithmeticae, which has influenced developments since. Among his achievements, he was the first to work out how to make a 17-sided polygon, he predicted the orbit of the minor planet Ceres, rediscovering it, he found a way of sending signals along a wire, using electromagnetism, the first electromagnetic telegraph, and he advanced the understanding of parallel lines on curved surfaces. With Marcus du Sautoy
Professor of Mathematics and Simonyi Professor for the Public Understanding of Science at the University of OxfordColva Roney-Dougal
Reader in Pure Mathematics at the University of St AndrewsAnd Nick Evans
Professor of Theoretical Physics at the University of SouthamptonProducer: Simon Tillotson.

Carl Friedrich Gauss

After 27 years, Melvyn Bragg has decided to step down from the In Our Time presenter’s chair. With over a thousand episodes to choose from, he has selected just six that capture the huge range and depth of the subjects he and his experts have tackled. In this sixth of his choices, we hear Melvyn Bragg and his guests in 2017 discussing new discoveries about dinosaurs.Their topic is the development of theories about dinosaur feathers, following discoveries of fossils which show evidence of those feathers. All dinosaurs were originally thought to be related to lizards (the word 'dinosaur' was created from the Greek for 'terrible lizard') but that now appears false. In the last century, discoveries of fossils with feathers established that at least some dinosaurs were feathered and that some of those survived the great extinctions and evolved into the birds we see today. There are still many outstanding areas for study, such as what sorts of feathers they were, where on the body they were found, what their purpose was and which dinosaurs had them. With Mike Benton
Professor of Vertebrate Palaeontology at the University of BristolSteve Brusatte
Reader and Chancellor's Fellow in Vertebrate Palaeontology at the University of EdinburghandMaria McNamara
Senior Lecturer in Geology at University College, CorkProducer: Simon TillotsonSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the characters, events and discoveries that have shaped our world

Feathered Dinosaurs

After 27 years, Melvyn Bragg has decided to step down from the In Our Time presenter’s chair. With over a thousand episodes to choose from, he has selected just six that capture the huge range and depth of the subjects he and his experts have tackled. In this fourth of his choices, we hear Melvyn Bragg and his guests discuss bird migration. Their topic includes why some birds migrate and others do not, how they select their destinations and how they navigate the great distances, often over oceans. For millennia, humans set their calendars to birds' annual arrivals, and speculated about what happened when they departed, perhaps moving deep under water, or turning into fish or shellfish, or hibernating while clinging to trees upside down. Ideas about migration developed in C19th when, in Germany, a stork was noticed with an African spear in its neck, indicating where it had been over the winter and how far it had flown. Today there are many ideas about how birds use their senses of sight and smell, and magnetic fields, to find their way, and about why and how birds choose their destinations and many questions. Why do some scatter and some flock together, how much is instinctive and how much is learned, and how far do the benefits the migrating birds gain outweigh the risks they face?With Barbara Helm
Reader at the Institute of Biodiversity, Animal Health and Comparative Medicine at the University of GlasgowTim Guilford
Professor of Animal Behaviour and Tutorial Fellow of Zoology at Merton College, Oxfordand Richard Holland
Senior Lecturer in Animal Cognition at Bangor UniversityProducer: Simon Tillotson
In Our Time is a BBC Studios ProductionSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the characters, events and discoveries that have shaped our world

Bird Migration

Melvyn Bragg and guests discuss enzymes, the proteins that control the speed of chemical reactions in living organisms. Without enzymes, these reactions would take place too slowly to keep organisms alive: with their actions as catalysts, changes which might otherwise take millions of years can happen hundreds of times a second. Some enzymes break down large molecules into smaller ones, like the ones in human intestines, while others use small molecules to build up larger, complex ones, such as those that make DNA. Enzymes also help keep cell growth under control, by regulating the time for cells to live and their time to die, and provide a way for cells to communicate with each other. With Nigel Richards
Professor of Biological Chemistry at Cardiff UniversitySarah Barry
Lecturer in Chemical Biology at King's College LondonAnd Jim Naismith
Director of the Research Complex at Harwell
Bishop Wardlaw Professor of Chemical Biology at the University of St Andrews
Professor of Structural Biology at the University of OxfordProducer: Simon Tillotson.

Enzymes

Melvyn Bragg and guests discuss the life and work of Louis Pasteur (1822-1895) and his extraordinary contribution to medicine and science. It is said few people have saved more lives than Pasteur. A chemist, he showed that otherwise identical molecules could exist as 'left' and 'right-handed' versions and that molecules produced by living things were always left-handed. He proposed a germ theory to replace the idea of spontaneous generation. He discovered that microorganisms cause fermentation and disease. He began the process named after him, pasteurisation, heating liquids to 50-60 C to kill microbes. He saved the beer and wine industries in France when they were struggling with microbial contamination. He saved the French silk industry when he found a way of protecting healthy silkworm eggs from disease. He developed vaccines against anthrax and rabies and helped establish immunology. Many of his ideas were developed further after his lifetime, but one of his legacies was a charitable body, the Pasteur Institute, to continue research into infectious disease.With Andrew Mendelsohn
Reader in the School of History at Queen Mary, University of LondonAnne Hardy
Honorary Professor at the Centre for History in Public Health at the London School of Hygiene and Tropical Medicineand Michael Worboys
Emeritus Professor in the History of Science, Technology and Medicine at the University of Manchester Producer: Simon Tillotson.

Louis Pasteur

After 27 years, Melvyn Bragg has decided to step down from the In Our Time presenter’s chair. With over a thousand episodes to choose from, he has selected just six that capture the huge range and depth of the subjects he and his experts have tackled. In this fifth of his choices, we hear Melvyn Bragg and his guests discuss a key figure from quantum mechanics.Their topic is the life and ideas of Wolfgang Pauli (1900-1958), whose Exclusion Principle is one of the key ideas in quantum mechanics. A brilliant physicist, at 21 Pauli wrote a review of Einstein's theory of general relativity and that review is still a standard work of reference today. The Pauli Exclusion Principle proposes that no two electrons in an atom can be at the same time in the same state or configuration, and it helps explain a wide range of phenomena such as the electron shell structure of atoms. Pauli went on to postulate the existence of the neutrino, which was confirmed in his lifetime. Following further development of his exclusion principle, Pauli was awarded the Nobel Prize in Physics in 1945 for his 'decisive contribution through his discovery of a new law of Nature'. He also had a long correspondence with Jung, and a reputation for accidentally breaking experimental equipment which was dubbed The Pauli Effect.With Frank Close
Fellow Emeritus at Exeter College, University of OxfordMichela Massimi
Professor of Philosophy of Science at the University of EdinburghandGraham Farmelo
Bye-Fellow of Churchill College, University of CambridgeProducer: Simon TillotsonSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the characters, events and discoveries that have shaped our world

Pauli's Exclusion Principle

Melvyn Bragg and guests discuss the high temperatures that marked the end of the Paleocene and start of the Eocene periods, about 50m years ago. Over c1000 years, global temperatures rose more than 5 C on average and stayed that way for c100,000 years more, with the surface of seas in the Arctic being as warm as those in the subtropics. There were widespread extinctions, changes in ocean currents, and there was much less oxygen in the sea depths. The rise has been attributed to an increase of carbon dioxide and methane in the atmosphere, though it is not yet known conclusively what the source of those gases was. One theory is that a rise in carbon dioxide, perhaps from volcanoes, warmed up the globe enough for warm water to reach the bottom of the oceans and so release methane from frozen crystals in the sea bed. The higher the temperature rose and the longer the water was warm, the more methane was released. Scientists have been studying a range of sources from this long period, from ice samples to fossils, to try to understand more about possible causes. With Dame Jane Francis
Professor of Palaeoclimatology at the British Antarctic SurveyMark Maslin
Professor of Palaeoclimatology at University College LondonAndTracy Aze
Lecturer in Marine Micropaleontology at the University of LeedsProducer: Simon Tillotson.

The Paleocene-Eocene Thermal Maximum

Melvyn Bragg and guests discuss the Kuiper Belt, a vast region of icy objects at the fringes of our Solar System, beyond Neptune, in which we find the dwarf planet Pluto and countless objects left over from the origins of the solar system, some of which we observe as comets. It extends from where Neptune is, which is 30 times further out than the Earth is from the Sun, to about 500 times the Earth-Sun distance. It covers an immense region of space and it is the part of the Solar System that we know the least about, because it is so remote from us and has been barely detectable by Earth-based telescopes until recent decades. Its existence was predicted before it was known, and study of the Kuiper Belt, and how objects move within it, has led to a theory that there may be a 9th planet far beyond Neptune.WithCarolin Crawford
Public Astronomer at the Institute of Astronomy and Fellow of Emmanuel College, University of CambridgeMonica Grady
Professor of Planetary and Space Sciences at the Open UniversityAndStephen Lowry
Reader in Planetary and Space Sciences, University of KentProducer: Simon Tillotson.

The Kuiper Belt

Melvyn Bragg and guests discuss the flourishing of maths in the early Islamic world, as thinkers from across the region developed ideas in places such as Baghdad's House of Wisdom. Among them were the Persians Omar Khayyam, who worked on equations, and Al-Khwarizmi, latinised as Algoritmi and pictured above, who is credited as one of the fathers of algebra, and the Jewish scholar Al-Samawal, who converted to Islam and worked on mathematical induction. As well as the new ideas, there were many advances drawing on Indian, Babylonian and Greek work and, thanks to the recording or reworking by mathematicians in the Islamic world, that broad range of earlier maths was passed on to western Europe for further study.With Colva Roney-Dougal
Reader in Pure Mathematics at the University of St AndrewsPeter Pormann
Professor of Classics & Graeco-Arabic Studies at the University of ManchesterAndJim Al-Khalili
Professor of Physics at the University of SurreyProducer: Simon Tillotson.

Maths in the Early Islamic World

Melvyn Bragg and guests discuss the relationship between parasites and hosts, where one species lives on or in another to the benefit of the parasite but at a cost to the host, potentially leading to disease or death of the host. Typical examples are mistletoe and trees, hookworms and vertebrates, cuckoos and other birds. In many cases the parasite species do so well in or on a particular host that they reproduce much faster and can adapt to changes more efficiently, and it is thought that almost half of all animal species have a parasitic stage in their lifetime. What techniques do hosts have to counter the parasites, and what impact do parasites have on the evolution of their hosts? With Steve Jones
Emeritus Professor of Genetics at University College, LondonWendy Gibson
Professor of Protozoology at the University of Bristoland Kayla King
Associate Professor in the Department of Zoology at the University of OxfordProducer: Simon Tillotson.

Parasitism

Melvyn Bragg and guests discuss the German astronomer Johannes Kepler (1571 - 1630). Although he is overshadowed today by Isaac Newton and Galileo, he is considered by many to be one of the greatest scientists in history. The three laws of planetary motion Kepler developed transformed people's understanding of the Solar System and laid the foundations for the revolutionary ideas Isaac Newton produced later. Kepler is also thought to have written one of the first works of science fiction. However, he faced a number of challenges. He had to defend his mother from charges of witchcraft, he had few financial resources and his career suffered as a result of his Lutheran faith.  
With
David Wootton
Professor of History at the University of YorkUlinka Rublack 
Professor of Early Modern European History at the University of Cambridge and Fellow of St John's CollegeAdam Mosley 
Associate Professor in the Department of History at Swansea University Producer: Victoria Brignell.

Johannes Kepler

The scientist John Dalton was born in North England in 1766. Although he came from a relatively poor Quaker family, he managed to become one of the most celebrated scientists of his age. Through his work, he helped to establish Manchester as a place where not only products were made but ideas were born. His reputation during his lifetime was so high that unusually a statue was erected to him before he died. Among his interests were meteorology, gasses and colour blindness. However, he is most remembered today for his pioneering thinking in the field of atomic theory. With: Jim Bennett
Former Director of the Museum of the History of Science at the University of Oxford and Keeper Emeritus at the Science MuseumAileen Fyfe
Reader in British History at the University of St AndrewsJames Sumner
Lecturer in the History of Technology at the Centre for the History of Science, Technology and Medicine at the University of ManchesterProducer: Victoria Brignell.

John Dalton

Melvyn Bragg and guests discuss plasma, the fourth state of matter after solid, liquid and gas. As over ninety-nine percent of all observable matter in the Universe is plasma, planets like ours, with so little plasma and so much solid, liquid and gas, appear all the more remarkable. On the grand scale, plasma is what the Sun is made from and, when we look into the night sky, almost everything we can see with the naked eye is made of plasma. On the smallest scale, here on Earth, scientists make plasma to etch the microchips on which we rely for so much. Plasma is in the fluorescent light bulbs above our heads and, in laboratories around the world, it is the subject of tests to create, one day, an inexhaustible and clean source of energy from nuclear fusion.With Justin Wark
Professor of Physics and Fellow of Trinity College at the University of OxfordKate Lancaster
Research Fellow for Innovation and Impact at the York Plasma Institute at the University of Yorkand Bill Graham
Professor of Physics at Queens University, BelfastProducer: Simon Tillotson.

Plasma

After 27 years, Melvyn Bragg has decided to step down from the In Our Time presenter’s chair. With over a thousand episodes to choose from, he has selected just six that capture the huge range and depth of the subjects he and his experts have tackled. In this third of his choices, we hear Melvyn Bragg and his guests discuss Greek philosophy.Their topic is Zeno of Elea, a pre-Socratic philosopher from c490-430 BC whose paradoxes were described by Bertrand Russell as "immeasurably subtle and profound." The best known argue against motion, such as that of an arrow in flight which is at a series of different points but moving at none of them, or that of Achilles who, despite being the faster runner, will never catch up with a tortoise with a head start. Aristotle and Aquinas engaged with these, as did Russell, yet it is still debatable whether Zeno's Paradoxes have been resolved.With Marcus du Sautoy
Professor of Mathematics and Simonyi Professor for the Public Understanding of Science at the University of OxfordBarbara Sattler 
Lecturer in Philosophy at the University of St Andrewsand James Warren
Reader in Ancient Philosophy at the University of CambridgeProducer: Simon Tillotson
In Our Time is a BBC Studios ProductionSpanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the characters, events and discoveries that have shaped our world

Zeno's Paradoxes

Melvyn Bragg and guests discuss the development of photography in the 1830s, when techniques for 'drawing with light' evolved to the stage where, in 1839, both Louis Daguerre and William Henry Fox Talbot made claims for its invention. These followed the development of the camera obscura, and experiments by such as Thomas Wedgwood and Nicéphore Niépce, and led to rapid changes in the 1840s as more people captured images with the daguerreotype and calotype. These new techniques changed the aesthetics of the age and, before long, inspired claims that painting was now dead.WithSimon Schaffer
Professor of the History of Science at the University of CambridgeElizabeth Edwards
Emeritus Professor of Photographic History at De Montfort UniversityAndAlison Morrison-Low, 
Research Associate at National Museums ScotlandProducer: Simon Tillotson.

The Invention of Photography

Melvyn Bragg and guests discuss penicillin, discovered by Alexander Fleming in 1928. It is said he noticed some blue-green penicillium mould on an uncovered petri dish at his hospital laboratory, and that this mould had inhibited bacterial growth around it. After further work, Fleming filtered a broth of the mould and called that penicillin, hoping it would be useful as a disinfectant. Howard Florey and Ernst Chain later shared a Nobel Prize in Medicine with Fleming, for their role in developing a way of mass-producing the life-saving drug. Evolutionary theory predicted the risk of resistance from the start and, almost from the beginning of this 'golden age' of antibacterials, scientists have been looking for ways to extend the lifespan of antibiotics.WithLaura Piddock
Professor of Microbiology at the University of BirminghamChristoph Tang
Professor of Cellular Pathology and Professorial Fellow at Exeter College at the University of OxfordAndSteve Jones
Emeritus Professor of Genetics at University College, LondonProducer: Simon Tillotson.

Penicillin

Melvyn Bragg and guests discuss Euclid's Elements, a mathematical text book attributed to Euclid and in use from its appearance in Alexandria, Egypt around 300 BC until modern times, dealing with geometry and number theory. It has been described as the most influential text book ever written. Einstein had a copy as a child, which he treasured, later saying "If Euclid failed to kindle your youthful enthusiasm, then you were not born to be a scientific thinker."With Marcus du Sautoy
Professor of Mathematics and Simonyi Professor for the Public Understanding of Science at the University of OxfordSerafina Cuomo
Reader in Roman History at Birkbeck University of LondonAnd June Barrow-Green
Professor of the History of Mathematics at the Open UniversityProducer: Simon Tillotson.

Euclid's Elements

Melvyn Bragg and guests discuss the impact of the eruption of Mt Tambora, in 1815, on the Indonesian island of Sambawa. This was the largest volcanic eruption in recorded history and it had the highest death toll, devastating people living in the immediate area. Tambora has been linked with drastic weather changes in North America and Europe the following year, with frosts in June and heavy rains throughout the summer in many areas. This led to food shortages, which may have prompted westward migration in America and, in a Europe barely recovered from the Napoleonic Wars, led to widespread famine. With Clive Oppenheimer
Professor of Volcanology at the University of CambridgeJane Stabler
Professor in Romantic Literature at the University of St AndrewsAndLawrence Goldman
Director of the Institute of Historical Research at the University of LondonProducer: Simon Tillotson.

1816, the Year Without a Summer

Melvyn Bragg and guests discuss the neutron, one of the particles found in an atom's nucleus. Building on the work of Ernest Rutherford, the British physicist James Chadwick won the Nobel Prize for Physics for his discovery of the neutron in 1932. Neutrons play a fundamental role in the universe and their discovery was at the heart of developments in nuclear physics in the first half of the 20th century. With Val Gibson
Professor of High Energy Physics at the University of Cambridge and fellow of Trinity CollegeAndrew Harrison
Chief Executive Officer of Diamond Light Source and Professor in Chemistry at the University of EdinburghAndFrank Close
Professor Emeritus of Physics at the University of Oxford.

The Neutron

Melvyn Bragg and guests discuss the life and work of Robert Hooke (1635-1703) who worked for Robert Boyle and was curator of experiments at the Royal Society. The engraving of a flea, above, is taken from his Micrographia which caused a sensation when published in 1665. Sometimes remembered for his disputes with Newton, he studied the planets with telescopes and snowflakes with microscopes. He was an early proposer of a theory of evolution, discovered light diffraction with a wave theory to explain it and felt he was rarely given due credit for his discoveries. WithDavid Wootton
Anniversary Professor of History at the University of YorkPatricia Fara
President Elect of the British Society for the History of ScienceAndRob Iliffe
Professor of History of Science at Oxford UniversityProducer: Simon Tillotson.

Robert Hooke

Melvyn Bragg and guests discuss the origins, development and uses of chromatography. In its basic form, it is familiar to generations of schoolchildren who put a spot of ink at the bottom of a strip of paper, dip it in water and then watch the pigments spread upwards, revealing their separate colours. Chemists in the 19th Century started to find new ways to separate mixtures and their work was taken further by Mikhail Tsvet, a Russian-Italian scientist who is often credited with inventing chromatography in 1900. The technique has become so widely used, it is now an integral part of testing the quality of air and water, the levels of drugs in athletes, in forensics and in the preparation of pharmaceuticals.WithAndrea Sella
Professor of Chemistry at University College LondonApryll Stalcup
Professor of Chemical Sciences at Dublin City UniversityAndLeon Barron
Senior Lecturer in Forensic Science at King's College London.

Chromatography

Melvyn Bragg and guests discuss the planet Saturn with its rings of ice and rock and over 60 moons. In 1610, Galileo used an early telescope to observe Saturn, one of the brightest points in the night sky, but could not make sense of what he saw: perhaps two large moons on either side. When he looked a few years later, those supposed moons had disappeared. It was another forty years before Dutch scientist Christiaan Huygens solved the mystery, realizing the moons were really a system of rings. Successive astronomers added more detail, with the greatest leaps forward in the last forty years. The Pioneer 11 spacecraft and two Voyager missions have flown by, sending back the first close-up images, and Cassini is still there, in orbit, confirming Saturn, with its rings and many moons, as one of the most intriguing and beautiful planets in our Solar System. WithCarolin Crawford
Public Astronomer at the Institute of Astronomy and Fellow of Emmanuel College, University of CambridgeMichele Dougherty
Professor of Space Physics at Imperial College LondonAndAndrew Coates
Deputy Director in charge of the Solar System at the Mullard Space Science Laboratory at UCL.

Saturn

Melvyn Bragg and guests discuss the eminent 19th-century scientist Michael Faraday. Born into a poor working-class family, he received little formal schooling but became interested in science while working as a bookbinder's apprentice. He is celebrated today for carrying out pioneering research into the relationship between electricity and magnetism. Faraday showed that if a wire was turned in the presence of a magnet or a magnet was turned in relation to a wire, an electric current was generated. This ground-breaking discovery led to the development of the electric generator and ultimately to modern power stations. During his life he became the most famous scientist in Britain and he played a key role in founding the Royal Institution's Christmas lectures which continue today.With:Geoffrey Cantor
Professor Emeritus of the History of Science at the University of LeedsLaura Herz
Professor of Physics at the University of OxfordFrank James
Professor of the History of Science at the Royal InstitutionProducer: Victoria Brignell.

Michael Faraday

Melvyn Bragg and his guests discuss the evolution and role of Circadian Rhythms, the so-called body clock that influences an organism's daily cycle of physical, behavioural and mental changes. The rhythms are generated within organisms and also in response to external stimuli, mainly light and darkness. They are found throughout the living world, from bacteria to plants, fungi to animals and, in humans, are noticed most clearly in sleep patterns. WithRussell Foster
Professor of Circadian Neuroscience at the University of OxfordDebra Skene
Professor of Neuroendocrinology at the University of SurreyAndSteve Jones
Emeritus Professor of Genetics at University College London.

Circadian Rhythms

Melvyn Bragg and guests discuss the problem of P versus NP, which has a bearing on online security. There is a $1,000,000 prize on offer from the Clay Mathematical Institute for the first person to come up with a complete solution. At its heart is the question "are there problems for which the answers can be checked by computers, but not found in a reasonable time?" If the answer to that is yes, then P does not equal NP. However, if all answers can be found easily as well as checked, if only we knew how, then P equals NP. The area has intrigued mathematicians and computer scientists since Alan Turing, in 1936, found that it's impossible to decide in general whether an algorithm will run forever on some problems. Resting on P versus NP is the security of all online transactions which are currently encrypted: if it transpires that P=NP, if answers could be found as easily as checked, computers could crack passwords in moments.With Colva Roney-Dougal
Reader in Pure Mathematics at the University of St AndrewsTimothy Gowers
Royal Society Research Professor in Mathematics at the University of CambridgeAnd Leslie Ann Goldberg
Professor of Computer Science and Fellow of St Edmund Hall, University of OxfordProducer: Simon Tillotson.

P v NP

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.

Perpetual Motion

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.

Extremophiles

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.

The Science of Glass

Melvyn Bragg and his guests discuss the Earth's Core. The inner core is an extremely dense, solid ball of iron and nickel, the size of the Moon, while the outer core is a flowing liquid, the size of Mars. Thanks to the magnetic fields produced within the core, life on Earth is possible. The magnetosphere protects the Earth from much of the Sun's radiation and the flow of particles which would otherwise strip away the atmosphere. The precise structure of the core and its properties have been fascinating scientists from the Renaissance. Recent seismographs show the picture is even more complex than we might have imagined, with suggestions that the core is spinning at a different speed and on a different axis from the surface.WithStephen Blundell
Professor of Physics and Fellow of Mansfield College at the University of OxfordArwen Deuss
Associate Professor in Seismology at Utrecht UniversityandSimon Redfern
Professor of Mineral Physics at the University of CambridgeProducer: Simon Tillotson.

The Earth's Core

Melvyn Bragg and his guests discuss the scientific achievements of the Curie family. In 1903 Marie and Pierre Curie shared a Nobel Prize in Physics with Henri Becquerel for their work on radioactivity, a term which Marie coined. Marie went on to win a Nobel in Chemistry eight years later; remarkably, her daughter Irène Joliot-Curie would later share a Nobel with her husband Frédéric Joliot-Curie for their discovery that it was possible to create radioactive materials in the laboratory. The work of the Curies added immensely to our knowledge of fundamental physics and paved the way for modern treatments for cancer and other illnesses.With:Patricia Fara
Senior Tutor of Clare College, University of CambridgeRobert Fox
Emeritus Professor of the History of Science at the University of OxfordSteven T Bramwell
Professor of Physics and former Professor of Chemistry at University College LondonProducer: Simon Tillotson.

The Curies

Melvyn Bragg and his guests discuss dark matter, the mysterious and invisible substance which is believed to make up most of the Universe. In 1932 the Dutch astronomer Jan Oort noticed that the speed at which galaxies moved was at odds with the amount of material they appeared to contain. He hypothesized that much of this 'missing' matter was simply invisible to telescopes. Today astronomers and particle physicists are still fascinated by the search for dark matter and the question of what it is.With Carolin Crawford
Public Astronomer at the Institute of Astronomy, University of Cambridge and Gresham Professor of AstronomyCarlos Frenk
Ogden Professor of Fundamental Physics and Director of the Institute for Computational Cosmology at the University of DurhamAnne Green
Reader in Physics at the University of NottinghamProducer: Simon Tillotson.

Dark Matter

Melvyn Bragg and his guests discuss the photon, one of the most enigmatic objects in the Universe. Generations of scientists have struggled to understand the nature of light. In the late nineteenth century it seemed clear that light was an electromagnetic wave. But the work of physicists including Planck and Einstein shed doubt on this theory. Today scientists accept that light can behave both as a wave and a particle, the latter known as the photon. Understanding light in terms of photons has enabled the development of some of the most important technology of the last fifty years.With:Frank Close
Professor Emeritus of Physics at the University of OxfordWendy Flavell
Professor of Surface Physics at the University of ManchesterSusan Cartwright
Senior Lecturer in Physics and Astronomy at the University of Sheffield.Producer: Thomas Morris.

The Photon

Melvyn Bragg and guests discuss Behavioural Ecology, the scientific study of animal behaviour.What factors influence where and what an animal chooses to eat? Why do some animals mate for life whilst others are promiscuous? Behavioural ecologists approach questions like these using Darwin's theory of natural selection, along with ideas drawn from game theory and the economics of consumer choice.Scientists had always been interested in why animals behave as they do, but before behavioural ecology this area of zoology never got much beyond a collection of interesting anecdotes. Behavioural ecology gave researchers techniques for constructing rigorous mathematical models of how animals act under different circumstances, and for predicting how they will react if circumstances change. Behavioural ecology emerged as a branch of zoology in the second half of the 20th century and proponents say it revolutionized our understanding of animals in their environments.GUESTSSteve Jones, Emeritus Professor of Genetics at University College LondonRebecca Kilner, Professor of Evolutionary Biology at the University of CambridgeJohn Krebs, Principal of Jesus College at the University of OxfordProducer: Luke Mulhall.

Behavioural Ecology

Melvyn Bragg and guests discuss Isambard Kingdom Brunel, the Victorian engineer responsible for bridges, tunnels and railways still in use today more than 150 years after they were built. Brunel represented the cutting edge of technological innovation in Victorian Britain, and his life gives us a window onto the social changes that accompanied the Industrial Revolution. Yet his work was not always successful, and his innovative approach to engineering projects was often greeted with suspicion from investors. Guests:Julia Elton, former President of the Newcomen Society for the History of Engineering and TechnologyBen Marsden, Senior Lecturer in the School of Divinity, History and Philosophy at the University of AberdeenCrosbie Smith, Professor of the History of Science at the University of KentProducer: Luke Mulhall.

Brunel

Melvyn Bragg and his guests discuss nuclear fusion, the process that powers stars. In the 1920s physicists predicted that it might be possible to generate huge amounts of energy by fusing atomic nuclei together, a reaction requiring enormous temperatures and pressures. Today we know that this complex reaction is what keeps the Sun shining. Scientists have achieved fusion in the laboratory and in nuclear weapons; today it is seen as a likely future source of limitless and clean energy.Guests:Philippa Browning, Professor of Astrophysics at the University of ManchesterSteve Cowley, Chief Executive of the United Kingdom Atomic Energy AuthorityJustin Wark, Professor of Physics and fellow of Trinity College at the University of OxfordProducer: Thomas Morris.

Nuclear Fusion

Melvyn Bragg and his guests discuss Euler's number, also known as e. First discovered in the seventeenth century by the Swiss mathematician Jacob Bernoulli when he was studying compound interest, e is now recognised as one of the most important and interesting numbers in mathematics. Roughly equal to 2.718, e is useful in studying many everyday situations, from personal savings to epidemics. It also features in Euler's Identity, sometimes described as the most beautiful equation ever written. With:Colva Roney-Dougal
Reader in Pure Mathematics at the University of St AndrewsJune Barrow-Green
Senior Lecturer in the History of Maths at the Open UniversityVicky Neale
Whitehead Lecturer at the Mathematical Institute and Balliol College at the University of OxfordProducer: Thomas Morris.

Melvyn Bragg and his guests discuss the Sun. The object that gives the Earth its light and heat is a massive ball of gas and plasma 93 million miles away. Thanks to the nuclear fusion reactions taking place at its core, the Sun has been shining for four and a half billion years. Its structure, and the processes that keep it burning, have fascinated astronomers for centuries. After the invention of the telescope it became apparent that the Sun is not a placid, steadily shining body but is subject to periodic changes in its appearance and eruptions of dramatic violence, some of which can affect us here on Earth. Recent space missions have revealed fascinating new insights into our nearest star.With:Carolin Crawford
Gresham Professor of Astronomy and Fellow of Emmanuel College, CambridgeYvonne Elsworth
Poynting Professor of Physics at the University of BirminghamLouise Harra
Professor of Solar Physics at UCL Mullard Space Science LaboratoryProducer: Thomas Morris.

The Sun

Melvyn Bragg and his guests discuss the life and work of Robert Boyle, a pioneering scientist and a founder member of the Royal Society. Born in Ireland in 1627, Boyle was one of the first natural philosophers to conduct rigorous experiments, laid the foundations of modern chemistry and derived Boyle's Law, describing the physical properties of gases. In addition to his experimental work he left a substantial body of writings about philosophy and religion; his piety was one of the most important factors in his intellectual activities, prompting a celebrated dispute with his contemporary Thomas Hobbes.With:Simon Schaffer
Professor of the History of Science at the University of CambridgeMichael Hunter
Emeritus Professor of History at Birkbeck College, University of LondonAnna Marie Roos
Senior Lecturer in the History of Science and Medicine at the University of LincolnProducer: Thomas Morris.

Robert Boyle

Melvyn Bragg and his guests discuss photosynthesis, the process by which green plants and many other organisms use sunlight to synthesise organic molecules.  Photosynthesis arose very early in evolutionary history and has been a crucial driver of life on Earth. In addition to providing most of the food consumed by organisms on the planet, it is also responsible for maintaining atmospheric oxygen levels, and is thus almost certainly the most important chemical process ever discovered.With:Nick Lane
Reader in Evolutionary Biochemistry at University College LondonSandra Knapp
Botanist at the Natural History MuseumJohn Allen
Professor of Biochemistry at Queen Mary, University of London.Producer: Thomas Morris

Photosynthesis

Melvyn Bragg and his guests discuss the science of matter and the states in which it can exist. Most people are familiar with the idea that a substance like water can exist in solid, liquid and gaseous forms. But as much as 99% of the matter in the universe is now believed to exist in a fourth state, plasma. Today scientists recognise a number of other exotic states or phases, such as glasses, gels and liquid crystals - many of them with useful properties that can be exploited.With:Andrea Sella
Professor of Chemistry at University College LondonAthene Donald
Professor of Experimental Physics at the University of CambridgeJustin Wark
Professor of Physics and Fellow of Trinity College at the University of OxfordProducer: Thomas Morris.

States of Matter

Melvyn Bragg and his guests discuss the eye. Humans have been attempting to understand the workings and significance of the organ for at least 2500 years. Some ancient philosophers believed that the eye enabled creatures to see by emitting its own light. The function and structures of the eye became an area of particular interest to doctors in the Islamic Golden Age. In Renaissance Europe the work of thinkers including Kepler and Descartes revolutionised thinking about how the organ worked, but it took several hundred years for the eye to be thoroughly understood. Eyes have long attracted more than purely scientific interest, known even today as the 'windows on the soul'.With:Patricia Fara
Senior Tutor of Clare College, University of CambridgeWilliam Ayliffe
Gresham Professor of Physic at Gresham CollegeRobert Iliffe
Professor of Intellectual History and History of Science at the University of SussexProducer: Thomas Morris.

The Eye

Melvyn Bragg and his guests discuss Social Darwinism. After the publication of Charles Darwin's masterpiece On the Origin of Species in 1859, some thinkers argued that Darwin's ideas about evolution could also be applied to human society. One thinker particularly associated with this movement was Darwin's near-contemporary Herbert Spencer, who coined the phrase 'survival of the fittest'. He argued that competition among humans was beneficial, because it ensured that only the healthiest and most intelligent individuals would succeed. Social Darwinism remained influential for several generations, although its association with eugenics and later adoption as an ideological position by Fascist regimes ensured its eventual downfall from intellectual respectability.With:Adam Kuper
Centennial Professor of Anthropology at the LSE, University of LondonGregory Radick
Professor of History and Philosophy of Science at the University of LeedsCharlotte Sleigh
Reader in the History of Science at the University of Kent.Producer: Thomas Morris.

Social Darwinism

Melvyn Bragg and his guests discuss Catastrophism, the idea that natural disasters have had a significant influence in moulding the Earth's geological features. In 1822 William Buckland, the first reader of Geology at the University of Oxford, published his famous Reliquae Diluvianae, in which he ascribed most of the fossil record to the effects of Noah's flood. Charles Lyell in his Principles of Geology challenged these writings, arguing that geological change was slow and gradual, and that the processes responsible could still be seen at work today - a school of thought known as Uniformitarianism. But in the 1970s the idea that natural catastrophes were a major factor in the Earth's geology was revived and given new respectability by the discovery of evidence of a gigantic asteroid impact 65 million years ago, believed by many to have resulted in the extinction of the dinosaurs.With:Andrew Scott
Leverhulme Emeritus Fellow in the Department of Earth Sciences at Royal Holloway, University of LondonJan Zalasiewicz
Senior Lecturer in Geology at the University of LeicesterLeucha Veneer
Visiting Scholar at the Faculty of Life Sciences at the University of ManchesterProducer: Thomas Morris.