Paul Dirac

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)

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)

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)

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)

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

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

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

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.

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

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