Melvyn Bragg and his guests discuss the origins of infectious disease. Infectious disease has been with us for millennia. There are reports of ancient outbreaks of plague in the Bible, and in numerous historical sources from China, the Middle East and Europe. Other infections, including smallpox, tuberculosis and measles, have also been known for centuries. But some diseases made their first appearances only recently: HIV emerged around a century ago, while the Ebola virus was first recorded in the 1970s.But where do the agents of disease come from, and what determines where and when new viruses and bacteria appear? Modern techniques allow scientists to trace the histories of infective agents through their genomes; the story of disease provides a fascinating microcosm of the machinery of evolution.With:Steve JonesProfessor of Genetics at University College LondonSir Roy AndersonProfessor of Infectious Disease Epidemiology at Imperial College LondonMark PallenProfessor of Microbial Genomics at the University of Birmingham.Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the neutrino.In 1930 the physicist Wolfgang Pauli proposed the existence of an as-yet undiscovered subatomic particle. He also bet his colleagues a case of champagne that it would never be detected. He lost his bet when in 1956 the particle, now known as the neutrino, was first observed in an American nuclear reactor. Neutrinos are some of the most mysterious particles in the Universe. The Sun produces trillions of them every second, and they constantly bombard the Earth and everything on it. Neutrinos can pass through solid rock, and even stars, at almost the speed of light without being impeded, and are almost impossible to detect. Today, experiments involving neutrinos are providing insights into the nature of matter, the contents of the Universe and the processes deep inside stars.With:Frank CloseProfessor of Physics at Exeter College at the University of OxfordSusan CartwrightSenior Lecturer in Particle Physics and Astrophysics at the University of SheffieldDavid WarkProfessor of Particle Physics at Imperial College, London, and the Rutherford Appleton Laboratory. Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the age of the Universe.Since the 18th century, when scientists first realised that the Universe had existed for more than a few thousand years, cosmologists have debated its likely age. The discovery that the Universe was expanding allowed the first informed estimates of its age to be made by the great astronomer Edwin Hubble in the early decades of the twentieth century. Hubble's estimate of the rate at which the Universe is expanding, the so-called Hubble Constant, has been progressively improved. Today cosmologists have a variety of other methods for ageing the Universe, most recently the detailed measurements of cosmic microwave background radiation - the afterglow of the Big Bang - made in the last decade. And all these methods seem to agree on one thing: the Universe has existed for around 13.75 billion years.With:Martin ReesAstronomer Royal and Emeritus Professor of Cosmology and Astrophysics at the University of CambridgeCarolin CrawfordMember of the Institute of Astronomy and Fellow of Emmanuel College at the University of CambridgeCarlos FrenkDirector of the Institute for Computational Cosmology at the University of Durham.Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the nervous system.

Most animals have a nervous system, a network of nerve tissues which allows parts of the body to communicate with each other. In humans the most significant parts of this network are the brain, spinal column and retinas, which together make up the central nervous system. But there is also a peripheral nervous system, which enables sensation, movement and the regulation of the major organs.

Scholars first described the nerves of the human body over two thousand years ago. For 1400 years it was believed that they were animated by 'animal spirits', mysterious powers which caused sensation and movement. In the eighteenth century scientists discovered that nerve fibres transmitted electrical impulses; it was not until the twentieth century that chemical agents - neurotransmitters - were first identified.

With:

Colin Blakemore

Vivian Nutton

Tilli Tansey

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss randomness and pseudorandomness.Randomness is the mathematics of the unpredictable. Dice and roulette wheels produce random numbers: those which are unpredictable and display no pattern. But mathematicians also talk of 'pseudorandom' numbers - those which appear to be random but are not. In the last century random numbers have become enormously useful to statisticians, computer scientists and cryptographers. But true randomness is difficult to find, and mathematicians have devised many ingenious solutions to harness or simulate it. These range from the Premium Bonds computer ERNIE (whose name stands for Electronic Random Number Indicator Equipment) to new methods involving quantum physics.Digital computers are incapable of behaving in a truly random fashion - so instead mathematicians have taught them how to harness pseudorandomness. This technique is used daily by weather forecasters, statisticians, and computer chip designers - and it's thanks to pseudorandomness that secure credit card transactions are possible.With:Marcus du SautoyProfessor of Mathematics at the University of OxfordColva Roney-DougalSenior Lecturer in Pure Mathematics at the University of St AndrewsTimothy GowersRoyal Society Research Professor in Mathematics at the University of CambridgeProducer: Thomas Morris.

Melvyn Bragg and his guests discuss the innovations and influence of Thomas Edison, one of the architects of the modern age.Edison is popularly remembered as the man who made cheap electric light possible. Born in 1847, he began his career working in the new industry of telegraphy, and while still in his early twenties made major improvements to the technology of the telegraph. Not long afterwards he invented a new type of microphone which was used in telephones for almost a century. In the space of three productive years, Edison developed the phonograph and the first commercially viable light bulb and power distribution system. Many more inventions were to follow: he also played a part in the birth of cinema in the 1890s. When he died in 1931 he had patented no fewer than 1093 devices - the most prolific inventor in history. As the creator of the world's first industrial research laboratory he forever changed the way in which innovation took place.With:Simon SchafferProfessor of the History of Science, University of CambridgeKathleen BurkProfessor of History, University College LondonIwan MorusReader in History, University of AberystwythProducer: Thomas Morris.

Melvyn Bragg and his guests discuss the role played by women in Enlightenment science. During the eighteenth century the opportunities for women to gain a knowledge of science were minimal. Universities and other institutions devoted to research were the preserve of men. Yet many important contributions to the science of the Enlightenment were made by women. These ranged from major breakthroughs like those of the British astronomer Caroline Herschel, the first woman to discover a comet, to important translations of scientific literature such as Emilie du Chatelet's French version of Newton's Principia - and all social classes were involved, from the aristocratic amateur botanists to the women artisans who worked in London's workshops manufacturing scientific instruments.

With

Patricia Fara

Karen O'Brien

Judith Hawley

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the history of logic. Logic, the study of reasoning and argument, first became a serious area of study in the 4th century BC through the work of Aristotle. He created a formal logical system, based on a type of argument called a syllogism, which remained in use for over two thousand years. In the nineteenth century the German philosopher and mathematician Gottlob Frege revolutionised logic, turning it into a discipline much like mathematics and capable of dealing with expressing and analysing nuanced arguments. His discoveries influenced the greatest mathematicians and philosophers of the twentieth century and considerably aided the development of the electronic computer. Today logic is a subtle system with applications in fields as diverse as mathematics, philosophy, linguistics and artificial intelligence.With:A.C. GraylingProfessor of Philosophy at Birkbeck, University of LondonPeter MillicanGilbert Ryle Fellow in Philosophy at Hertford College at the University of OxfordRosanna KeefeSenior Lecturer in Philosophy at the University of Sheffield.Producer: Thomas Morris.

Melvyn Bragg and his guests discuss imaginary numbers. In the sixteenth century, a group of mathematicians in Bologna found a solution to a problem that had puzzled generations before them: a completely new kind of number. For more than a century this discovery was greeted with such scepticism that the great French thinker Rene Descartes dismissed it as an "imaginary" number.The name stuck - but so did the numbers. Long dismissed as useless or even fictitious, the imaginary number i and its properties were first explored seriously in the eighteenth century. Today the imaginary numbers are in daily use by engineers, and are vital to our understanding of phenomena including electricity and radio waves. With Marcus du SautoyProfessor of Mathematics at Oxford University Ian StewartEmeritus Professor of Mathematics at the University of WarwickCaroline SeriesProfessor of Mathematics at the University of WarwickProducer: Thomas Morris.

Melvyn Bragg and his guests discuss Pliny's Natural History.Some time in the first century AD, the Roman scholar Pliny the Elder published his Naturalis Historia, or Natural History, an enormous reference work which attempted to bring together knowledge on every subject under the sun. The Natural History contains information on zoology, astronomy, geography, minerals and mining and - unusually for a work of this period - a detailed treatise on the history of classical art. It's a fascinating snapshot of the state of human knowledge almost two millennia ago.Pliny's 37-volume magnum opus is one of the most extensive works of classical scholarship to survive in its entirety, and was being consulted by scholars as late as the Renaissance. It had a significant influence on intellectual history, and has provided the template for every subsequent encyclopaedia.With:Serafina CuomoReader in Roman History at Birkbeck, University of LondonAude DoodyLecturer in Classics at University College, DublinLiba TaubReader in the History and Philosophy of Science, Cambridge UniversityProducer: Thomas Morris.