Melvyn Bragg examines Quantum Gravity. Early in the 20th century physicists were startled by the realisation that the smallest things in the universe do not obey Newton’s laws of gravity. Ripe apples fall from trees, billiard balls roll mostly on the table and the moon orbits the Earth in thrall to its gravitational pull, but there is no such force of gravity at work in the world of very small things. It seems there is one set of rules for the realm of every day objects, and a very different set of laws for the quantum world - where tiny particles actually form the building blocks of all those larger things.But how can this be? It doesn’t appear to make sense. Physicists decided that there must be another theory - a much larger theory - that unites, incorporates and finally makes sense of these divided realms. And this has been the Holy Grail of physics ever since. With Dr John Gribbin, Visiting Fellow in Astronomy, University of Sussex; Lee Smolin, Professor of Physics, Centre for Gravitational Physics and Geometry, Pennsylvania State University and Visiting Professor of Physics at Imperial College, London; Dr Janna Levin, Advanced Fellow, Department of Applied Mathematics and Theoretical Physics, Cambridge University.

Melvyn Bragg and guests discuss what drove the British Empire, especially in Victoria’s century. Was it science, more specifically, the science of plants, of agriculture, a scientific notion of nature and the improvement of nature? Was this seemingly rather adjacent notion - that the source of Empire can be found in Kew Gardens, Royal, Botanical, rather than in the muzzle of a gun or in the purse of a plunderer or in the consciousness of a conqueror - was science “the force that was with us?” Francis Bacon said of the Irish in 1603, “We shall reclaim them from their barbarous manners…populate plant and make civil all the provinces of that kingdom ..as we are persuaded that it is one of the chief causes for which God hath brought us to the Imperial Crown of these Kingdoms”. Centuries later, at the height of the Empire, John Stuart Mill wrote in On Liberty: “Despotism is a legitimate mode of government in dealing with barbarians, provided the end be their improvement”. But - despotism aside - was this notion of ‘improvement’ really the driving force behind the Empire? And did the British Empire have any firm basis in believing that the ‘light of pure reason’ that it brought to its colonies was any brighter than the knowledge that existed before they came? With Richard Drayton, Professor of History at the University of Virginia and author of Nature’s Government: Science, Imperial Britain and the ‘Improvement’ of the World; Maria Misra, Lecturer in Modern History and fellow of Keble College Oxford; Ziauddin Sardar, Professor of Science and Technology Policy, Middlesex University.

Melvyn Bragg looks at the deep claims made for mathematics, the discipline some believe to be the soul and true key to the understanding of all life, from the petals on the sunflower to the pulse in our wrists. The notion that mathematics is akin to theology might take some taking in at first. But from the first, in the West, they were. To Pythagoras, numbers were mystical and “prove” God. To Plato, who, it is claimed, has driven mathematics for over two thousand years, the ideals beyond the reality of our lives are to be found in mathematical perfections, immutable truth, God again in numbers. Are mathematics there in the universe, waiting to be discovered as the great ocean lying before Newton - or are they constructs applied by us to the universe and imposed rather than uncovered? It’s a long way from chalky sums on the blackboard and the first careless swing of the compass. Galilei Galileo wrote, “The Universe cannot be read until we have learnt the language and become familiar with the characters in which it was written. It is written in mathematical language, and the letters are triangles, circles and other geometrical figures, without which means it is humanly impossible to comprehend a single word”. But is he right that mathematics is the script in which the universe was written, or is it really just one of many possible systems that humankind has invented to interpret our world? Is mathematics is a process of invention or a voyage of discovery?With Ian Stewart, Professor of Mathematics and Gresham Professor of Geometry, University of Warwick; Margaret Wertheim, science writer, journalist and author of Pythagoras’ Trousers; John D Barrow, Professor of Applied Mathematics and Theoretical Physics, University of Cambridge.

Melvyn Bragg and guests discuss role of Freudian analysis in understanding the great works of literature. Freud said, “The poets and philosophers before me discovered the unconscious. What I discovered was the scientific method by which the unconscious can be studied”. Psychoanalysis has always been more than a ‘talking cure’ and it has strong ties to literature, but one hundred years after the publication of the first great work of psychoanalysis, The Interpretation of Dreams, critics are putting the scientific basis of Freud’s work in grave doubt and he is in danger of being pitched in with poets. The great American critic Harold Bloom has said “Freud, the writer will survive the death of psychoanalysis”, and the analyst and writer Adam Phillips seems to go further in his new book Promises Promises where he writes, “I think of Freud as a romantic writer, and I read psychoanalysis as poetry, so I don’t have to worry whether it is true or even useful”.So what is the relationship of psychoanalysis to literature, and if it is to be reclassified as literature itself can it still be practised as a talking cure?With Adam Phillips, author of Promises Promises: Essays on Psychoanalysis and Literature; Malcolm Bowie, Marshal Foch Professor of French Literature, Oxford University; Lisa Appignanesi novelist and co-author of Freud’s Women.

Melvyn Bragg and guests discuss Evolutionary Psychology. Richard Dawkins redefined human nature in 1976, when he wrote in The Selfish Gene: “They swarm in huge colonies, safe inside giant lumbering robots, sealed off from the outside world, communicating with it by tortuous indirect routes, manipulating it by remote control. They are in you and me; they created us body and mind; and their preservation is the ultimate rational of our existence…they go by the name of genes and we are their survival machines”. Potent ideas like this have given birth to a new discipline, ‘Evolutionary Psychology’: It claims that all of human behaviour can be understood in terms of a single compulsion - we must sexually reproduce so that our genes will live on. How has this idea developed, what can it tell us of how we behave, and can it be trusted? With Janet Radcliffe Richards, Reader in Bioethics, University College, London; Nicholas Humphrey, Professor of Psychology, New School for Social Research, New York; Professor Steven Rose, Professor of Physic, Open University.

Melvyn Bragg and guests discuss the Laws of Nature. Since ancient times philosophers and physicists have tried to discover simple underlying principles that control the Universe: In the 6th Century BC Thales declared “Everything is water”, centuries later Aristotle claimed that all of creation was forged from four elements, Newton more successfully laid down the Law of Universal Gravitation and as we speak, contemporary scientists are struggling to complete the task of ‘String Theory’ - the quest to find a single over-arching equation that unites all of physics, and can perhaps explain the organisation of everything in existence.But are the Laws of Physics really ‘facts of life’? Is what is true in physics, true in all areas of existence? Is it even true in other areas of physics?With Mark Buchanan, physicist and author of Ubiquity; Professor Frank Close, theoretical physicist and author of Lucifer’s Legacy: The Meaning of Asymmetry; Nancy Cartwright, Professor of Philosophy, LSE.

Melvyn Bragg and guests discuss the question of consciousness, our sense of self, and how we are able to imagine things when they are not there, which are problems that have troubled the great minds of philosophy for thousands of years. Consciousness has been linked to language, has been married to the mind and divorced from the body; it has been denied to animals, opposed to the subconscious and declared irreducible, but still it defies definition, and the debate rages on as to why we evolved it at all. But perhaps science will finally provide the answer. With Professor Gerald Edelman, Director of the Neurosciences, Institute in California and winner of the Nobel Prize for Physiology or Medicine in 1972; Igor Aleksander is Professor of Neural Engineering Systems, Imperial College, London; Margaret Boden, Professor of Philosophy and Psychology, University of Sussex.

Melvyn Bragg and guests discuss the chemical elements. The aim and challenge in chemistry, according to the Encyclopaedia Britannica, is the understanding of the complex materials which constitute everything in existence since the Big Bang, when the whole universe emerged out of the two elements of hydrogen and helium. For Aristotle there were four elements: Earth, Air, Fire and Water. Now there are one hundred and eight, sixteen of which are produced artificially, and none of which figure in Aristotle's original four. But they are all still elements - defined as substances which cannot be broken down, the building blocks of all life.Today we have the key to understanding these elements, the Periodic Table, which is a pattern embedded in nature and was miraculously discovered in a dream. With Paul Strathern, former lecturer in philosophy and science, Kingston University and author of Mendeleyev's Dream: The Quest for the Elements; Dr Mary Archer, Visiting Professor of Chemistry at Imperial College, London; John Murrell, Emeritus Professor of Chemistry, University of Sussex.

Melvyn Bragg and guests discuss the evolution of the human species. Where did we come from - we being Homo Sapiens? Let’s not go back to the Big Bang or in search of Genesis, but sift through the evidence from biology, palaeontology, climatology and anthropology.The story of human evolution is one that stretches back over five million years, and during that time there are reckoned to have been between fifteen and twenty species of hominid to have walked this planet. From the earliest (Genus) Australopithecus (Species) Anamensis through times when there have been several divergent pre-human species existing at once, we have now arrived at a period unique in the history of the earth when a sole human species, Homo Sapiens, is in evidence right across the globe.With Leslie Aiello, Professor of Biological Anthropology, University College, London; Robert Foley, evolutionary ecologist, writer and lecturer in biological anthropology at Cambridge University; Mark Roberts, Field Archaeologist, Project Leader of Boxgrove excavation and the discoverer of ‘Boxgrove Man’.

Melvyn Bragg examines the science of taxonomy. The Argentinean author Jose Luis Borges illustrated the problematic nature of scientific classification when he quoted from an ancient Chinese Encyclopaedia, the Celestial Emporium of Benevolent Knowledge. On these remote pages, in a complete absence of Phylum, Genus and Species, animals are divided into: “(a) those that belong to the Emperor, (b) embalmed ones, (c) those that are trained, (d) suckling pigs” and “those that tremble as if they were mad” ending with “those drawn with a very fine camel's hair brush”, “others”, “those that have just broken the flower vase” and “those that at a distance resemble flies.”Perhaps our own system of classifying the natural world might seem just as fantastical to a more knowing mind, and perhaps underlying the Linnaean system that homo sapiens currently finds useful there are prejudices of our own which distort the scientific truth. How does natural history classify the ‘natural order’?With Colin Tudge, writer, scientist and author of The Variety of Life: A Survey and a Celebration of all the Creatures that Have Ever Lived; Dr Sandy Knapp, Research Botanist, Department of Botany, Natural History Museum, London; Henry Gee, Senior Editor of Nature and author of Deep Time: Cladistics, the Revolution in Evolution.