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

With

Jess Wade

Frank Close

And

Steven Bramwell

Producer: Simon Tillotson

Reading 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

Since plants have to mate and produce offspring while rooted to the spot, they have to be pollinated – by wind, water, or animals – most commonly insects. They use a surprising array of tricks to attract pollinators: striking colours, iridescent light effects, and enticing scents, to name but a few.

Insects, on the other hand, do not seek to pollinate plants – they are looking for food; so plants make sure it’s worth their while. Insects are also remarkably sophisticated in their ability to find, recognise and find their way inside flowers.

So pollination has evolved as a complex dance between plants and pollinators that is essential for life on earth to continue.

With

Beverley Glover, Director of the Cambridge University Botanic Garden

Jane Memmott, Professor of Ecology at the University of Bristol

And

Lars Chittka, Professor of Sensory and Behavioural Ecology at Queen Mary, University of London.

Producer: Eliane Glaser

Reading list:

Stephen L Buchmann and Gary Paul Nabhan, The Forgotten Pollinators (Island 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)

Timothy Walker, Pollination: The Enduring Relationship Between Plant and Pollinator (Princeton University Press, 2020)

In Our Time is a BBC Studios Audio Production

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.

Jonathan Chubb

Elinor Thompson

And

Merlin Sheldrake

Producer: Eliane Glaser

In Our Time is a BBC Studios Audio production

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

Saidul Islam

And

Oliver Shorttle

Producer: Simon Tillotson

Reading 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

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

Jo Marchant

And

Liba Taub

Producer: Simon Tillotson

Reading 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)

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

Katy Clough

And

Andrew Pontzen

Producer: Simon Tillotson

Reading 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

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

James Ebdon

And

Claas Kirchhelle

Producer: Simon Tillotson

In Our Time is a BBC Studios Audio Production

Reading 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)

Melvyn Bragg and guests discuss the planet which is closest to our Sun. We see it as an evening or a morning star, close to where the Sun has just set or is about to rise, and observations of Mercury helped Copernicus understand that Earth and the other planets orbit the Sun, so displacing Earth from the centre of our system. In the 20th century, further observations of Mercury helped Einstein prove his general theory of relativity. For the last 50 years we have been sending missions there to reveal something of Mercury's secrets and how those relate to the wider universe, and he latest, BepiColombo, is out there in space now.

With

Emma Bunce

David Rothery

And

Carolin Crawford

Producer: Simon Tillotson

Reading 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)

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

Jill Jonnes

And

Iwan Morus

Producer: Simon Tillotson

Reading 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

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

Harry Cliff

And

Frank Close

Producer: Simon Tillotson

Reading 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)