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.
With
Stephen Blundell
Professor of Physics and Fellow of Mansfield College at the University of Oxford
Arwen Deuss
Associate Professor in Seismology at Utrecht University
and
Simon Redfern
Professor of Mineral Physics at the University of Cambridge
Producer: Simon Tillotson.
Om Podcasten
Spanning 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.
History fans can learn about pivotal wars and societal upheavals, such as the rise and fall of Napoleon, the Sack of Rome in 1527, and the political intrigue of the Russian Revolution. Those fascinated by the lives of kings and queens can journey to Versailles to meet Marie Antoinette and Louis XIV the Sun King, or to Ancient Egypt to meet Cleopatra and Nerfertiti. Or perhaps you’re looking to explore the history of religion, from Buddhism’s early teachings to the Protestant Reformation.
If you’re interested in the stories behind iconic works of art, music and literature, dive in to discussions on the artistic genius of Michelangelo's Sistine Chapel and Van Gogh’s famous Sunflowers. From Gothic architecture to the works of Shakespeare, each episode of In Our Time offers new insight into humanity’s cultural achievements.
Those looking to enrich their scientific knowledge can hear episodes on black holes, the Periodic Table, and classical theories of gravity, motion, evolution and relativity. Learn how the discovery of penicillin revolutionised medicine, and how the death of stars can lead to the formation of new planets.
Lovers of philosophy will find episodes on the big issues that define existence, from free will and ethics, to liberty and justice. In what ways did celebrated philosophers such as Mary Wollstonecraft and Karl Marx push forward radical new ideas? How has the concept of karma evolved from the ancient Sanskrit texts of Hinduism to today? What was Plato’s concept of an ideal republic, and how did he explore this through the legend of the lost city of Atlantis?
In Our Time celebrates the pursuit of knowledge and the enduring power of ideas.