Melvyn Bragg and guests discuss one of the deepest problems in contemporary physics. It’s called the measurement problem and it emerged from the flurry of activity in the early 20th century that gave rise to Quantum Mechanics. If the most famous fruit in physics is an apple, the most famous animal in physics is a cat. Schrödinger’s cat is named after Edwin Schrödinger, a theoretical physicist who in the early 20th century helped to develop the radical theories of Quantum Mechanics. The cat does not actually exist – it is the subject of a thought experiment – in which the rules of quantum mechanics make it appear both dead and alive at the same time.The problem of a cat that is both dead and alive illustrates the challenges of quantum physics and at the heart of this apparent absurdity is a thing called the measurement problem.The measurement problem arises because we don’t really understand how the atoms that constitute our world behave. They are fundamentally mysterious to us, even shocking, and they defy our attempts to measure and make sense of them. Possible solutions range from the existence of multiple realities to the rather more mundane possibility of an error in our mathematics - but a solution, if found, could transform our understanding of reality. With Basil Hiley, Emeritus Professor of Physics at Birkbeck, University of London, Simon Saunders, Reader in Philosophy of Physics and University Lecturer in Philosophy of Science at the University of Oxford; Roger Penrose, Emeritus Rouse Ball Professor of Mathematics at the University of Oxford

Melvyn Bragg and guests discuss the Observatory in Jaipur with its vast and beautiful instruments built to make astronomical measurements of the stars. Commissioned in the early 18th century by the Rajput prince and child prodigy, Jai Singh, it was at the centre of attempts to marry hundreds of years of Indian and Persian astronomical tradition. The Observatory was also at the very centre of the city which was laid out according to astrological principles. Jai Singh’s observatory was the cutting edge of Indian astronomy but also a repository for aeons of Hindu and Islamic intellectual life. The instruments were extraordinarily accurate for the time but used no lenses and were built of masonry, not metal. They helped to develop astrological tables, immensely important in Hindu Society, and come down to us as a record of Indian astronomy on the cusp of colonialism. With Chandrika Kaul, Lecturer in Modern History at the University of St Andrews; David Arnold, Professor of Asian and Global History at the University of Warwick; Chris Minkowski, Professor in Sanskrit at the University of Oxford

To celebrate the 200th anniversary of the birth of Charles Darwin in 2009 and the 150th anniversary of the publication of On the Origin of Species, Melvyn Bragg presents a series about Darwin's life and work.Melvyn visits Darwin's home at Down House in Kent. Despite ill health and the demands of his family, Darwin continued researching and publishing until his death in April 1882.Featuring contributions from Darwin biographer Jim Moore, geneticist at University College London Steve Jones, Darwin expert Alison Pearn of the Darwin Correspondence Project and former garden curator at Down House Nick Biddle.

To celebrate the 200th anniversary of the birth of Charles Darwin and the 150th anniversary of the publication of On the Origin of Species, Melvyn Bragg presents a series about Darwin's life and work.How Darwin was eventually persuaded to publish On the Origin of Species in November 1859 and the book's impact on fellow scientists and the general public.Featuring contributions from Darwin biographer Jim Moore, Steve Jones, geneticist at University College London, Jim Secord of the Darwin Correspondence Project and Johannes Vogel, Sandy Knapp and Judith Magee, all of the National History Museum.

To celebrate the 200th anniversary of the birth of Charles Darwin and the 150th anniversary of the publication of On the Origin of Species, Melvyn Bragg presents a series about Darwin's life and work.Darwin's expedition aboard the Beagle in December 1831 and how his work during the voyage influenced and provided evidence for his theories.Featuring contributions from Darwin biographer Jim Moore, Steve Jones, geneticist at University College London, David Norman, Fellow of Christ's College Cambridge and Jenny Clack, curator of the University.

To celebrate the 200th anniversary of the birth of Charles Darwin in 2009 and the 150th anniversary of the publication of On the Origin of Species, Melvyn Bragg presents a series about Darwin's life and work.Melvyn tells the story of Darwin's early life in Shropshire and discusses the significance of the three years he spent at Cambridge, where his interests shifted from religion to natural science.Featuring contributions from Darwin biographer Jim Moore, geneticist at University College London Steve Jones, fellow of Christ's College Cambridge David Norman and assistant librarian at Christ's College Cambridge Colin Higgins.

Melvyn Bragg and guests discuss the physics of time. When writing the Principia Mathematica, Isaac Newton declared his hand on most of the big questions in physics. He outlined the nature of space, explained the motions of the planets and conceived the operation of gravity. He also laid down the law on time declaring: “Absolute, true, and mathematical time, of itself and from its own nature, flows equably without relation to anything external.” For Newton time was absolute and set apart from the universe, but with the theories of Albert Einstein time became more complicated; it could be squeezed and distorted and was different in different places.Time is integral to our experience of things but we find it very difficult to think about. It may not even exist and yet seems written into the existence of absolutely everything. With Jim Al-Khalili, Professor of Theoretical Physics and Chair in the Public Engagement in Science at the University of Surrey; Monica Grady, Professor of Planetary and Space Sciences at the Open University and Ian Stewart, Professor of Mathematics at the University of Warwick.

Melvyn Bragg and guests discuss the history of scientific ideas about heat. As anyone who’s ever burnt their hand will testify – heat is a pretty commonplace concept. Cups of coffee cool down, microwaves reheat them, water boils at 100 degrees and freezes on cold winter nights.Behind the everyday experience of hot things lies a complex story of ideas spread across Paris, Manchester and particularly Glasgow. It’s a story of brewing vats and steam engines, of fridges, thermometers and the heat death of the universe. But most importantly, it was the understanding and harnessing of heat that helped make the modern world of industry, engineering and technology.With Simon Schaffer, Professor of History of Science at the University of Cambridge and Fellow of Darwin College; Hasok Chang, Professor of Philosophy of Science at University College London and Joanna Haigh, Professor of Atmospheric Physics at Imperial College London

Melvyn Bragg and guests examine the relationship between the mind and the brain as they discuss recent developments in Neuroscience. In the mid-19th century a doctor had a patient who had suffered a stroke. The patient was unable to speak save for one word. The word was ‘Tan’ which became his name. When Tan died, the doctor discovered damage to the left side of his brain and concluded that the ability to speak was housed there. This is how neuroscience used to work – by examining the dead or investigating the damaged – but now things have changed. Imaging machines and other technologies enable us to see the active brain in everyday life, to observe the activation of its cells and the mass firing of its neuron batteries. Our extraordinary new knowledge of how the brain works has challenged concepts of free will and consciousness and opened up new ways of understanding the brain. Yet these new ideas seem to conform to some old ideas such as Freudian Psychoanalysis. But what picture of the brain has emerged, how has our understanding of it changed and what are the implications for understanding that most mysterious and significant of all phenomena – the human mind?With Martin Conway, Professor of Psychology at the University of Leeds; Gemma Calvert, Professor of Applied Neuroimaging at WMG, University of Warwick and David Papineau, Professor of Philosophy of Science at King’s College London.

Melvyn Bragg and guests discuss Vitalism, an 18th and 19th century quest for the spark of life. On a dreary night in November 1818, a young doctor called Frankenstein completed an experiment and described it in his diary: “I collected the instruments of life around me, that I might infuse a spark of being into the lifeless thing that lay at my feet…By the glimmer of the half-extinguished light, I saw the dull yellow eye of the creature open…”Frankenstein may seem an outlandish tale, but Mary Shelley wrote it when science was alive with ideas about what differentiated the living from the dead. This was Vitalism, a belief that living things possessed some spark of life, some vital principle, perhaps even a soul, that distinguished the quick from the dead and lifted them above dull matter. Electricity was a very real candidate; when an Italian scientist called Luigi Galvani made dead frogs twitch by applying electricity he thought he had found it. Vitalists aimed at unlocking the secret of life itself and they raised questions about what life is that are unresolved to this day. With Patricia Fara, Fellow of Clare College and Affiliated Lecturer in the Department of History and Philosophy of Science at Cambridge University; Andrew Mendelsohn, Senior Lecturer in the History of Science and Medicine at Imperial College, University of London and Pietro Corsi, Professor of the History of Science at the University of Oxford.