In Our Time: Science

Melvyn Bragg and guests discuss prime numbers: 2, 3, 5, 7, 11, 13, 17 … This sequence of numbers goes on literally forever. Recently, a team of researchers in Missouri successfully calculated the highest prime number - it has 9.1 million digits. For nearly two and a half thousand years, since Euclid first described the prime numbers in his book Elements, mathematicians have struggled to write a rule to predict what comes next in the sequence. The Swiss mathematician Leonhard Euler feared that it is "a mystery into which the human mind will never penetrate." But others have been more hopeful... In the middle of the nineteenth century, the German mathematician Bernhard Riemann discovered a connection between prime numbers and a complex mathematical function called the 'zeta function'. Ever since, mathematicians have laboured to prove the existence of this connection and reveal the rules behind the elusive sequence. What exactly are prime numbers and what secrets might they unlock about our understanding of atom

Melvyn Bragg and guests discuss artificial intelligence. Can machines think? It was a question posed by the mathematician and Bletchley Park code breaker Alan Turing and it is a question still being asked today. What is the difference between men and machines and what does it mean to be human? And if we can answer that question, is it possible to build a computer that can imitate the human mind? There are those who have always had robust answers to the questions that those who seek to create artificial intelligence have posed. In 1949 the eminent neurosurgeon, Professor Geoffrey Jefferson argued that the mechanical mind could never rival a human intelligence because it could never be conscious of what it did: "Not until a machine can write a sonnet or compose a concerto because of thoughts and emotions felt", he declared "and not by the chance fall of symbols, could we agree that machine equals brain - that is, not only write it but know that it had written it." Yet the quest rolled on for machines that were

Melvyn Bragg and guests discuss the search for the Graviton particle. Albert Einstein said "I know why there are so many people who love chopping wood. In this activity one immediately sees the results". Einstein spent the last thirty years of his life trying to find a theory that would unify electromagnetism with gravity, but success eluded him. The search is still on for a unifying theory of gravitational force and hopes are pinned on the location of the graviton - a hypothetical elementary particle that transmits the force of gravity. But the graviton is proving hard to find. Indeed, the Large Hadron Collider at CERN still won't allow us to detect gravitons per se, but might be able to prove their existence in other ways. The idea of the graviton particle first emerged in the middle of the 20th century, when the notion that particles as mediators of force was taken seriously. Physicists believed that it could be applicable to gravity and by the late 20th century the hunt was truly on for the ultimate theor

Melvyn Bragg and guests discuss the unique properties of asteroids. They used to be regarded as the 'vermin of the solar system', irritating rubble that got in the way of astronomers trying to study more interesting phenomena. It was difficult or even impossible for an observer of asteroids to book time using the world's best telescopes, because they were regarded as unspectacular objects that could tell us little about the origins of the universe. However, that has all changed. It is now thought that asteroids are the unused building blocks of planets, 'pristine material' that has remained chemically unchanged since the creation of the solar system; a snapshot of matter at the beginning of time. At the moment the Japanese probe Hayabusa is 180 million miles away, pinned to the back of the asteroid Itokawa, attempting to gain our first samples of the chemical composition of an asteroid. Why did asteroids fail to form planets? How do they differ from their celestial cousins, the comets? And are either of them

Melvyn Bragg and guests discuss the rise of the mammals. The Cenozoic Era of Earth's history began 65 million years ago and runs to this day. It began with the extraordinary 'KT event', a supposed asteroid impact that destroyed the dinosaurs, and incorporates the break up of Pangaea, the enormous landmass that eventually formed the continents we know today. It is known as the 'Age of the Mammals', and it is the period in which warm-blooded, lactating, often furry animals diversified rapidly and spread across the globe on land and in the sea. According to evolutionary theory, what conditions created the opportunity for mammals to thrive? What environmental factors lead to the characteristics they share - and the features they don't? And how did they become the most intelligent class of animals on the planet? With Richard Corfield, Senior Lecturer in Earth Sciences at the Open University; Steve Jones, Professor of Genetics at University College London; Jane Francis, Professor of Palaeoclimatology at the Univers

Melvyn Bragg and guests discuss the history of magnetism. Pliny the Elder, in his Historia Naturalis, tells a story of a legendary Greek shepherd called Magnes who, while guiding his flock on Mount Ida, suddenly found it hard to move his feet. The nails of his sandals held fast to the rock beneath them, and the iron tip of his crook was strangely attracted to the boulders all around. Magnes had stumbled across the lodestone, or 'Magnetite', and discovered the phenomenon of magnetism. Plato was baffled by this strange force, as were Aristotle and Galen, and despite being used in navigation, supposedly suspended over the body of Mohammed and deployed in the pursuit of medical cures. St Thomas Aquinas thought magnets had souls. it was not until the late 16th century that any serious scientific attempt was made to explain the mystifying powers of the magnet. Descartes developed a particle theory of magnetism but the great Isaac Newton fought shy of the problem of what caused magnets to attract and repelWho pione

Melvyn Bragg and guests discuss the KT Boundary. Across the entire planet, where it hasn't been eroded or destroyed in land movements, there is a thin grey line. In Italy it is 1 cm thick, in America it stretches to three centimetres, but it is all the same thin grey line laid into the rock some 65 million years ago and it bears witness to a cataclysmic event experienced only once in Earth's history. It is called the KT Boundary and geologists believe it is the clue to the death of the dinosaurs and the ultimate reason why mammals and humans inherited the Earth.But exactly what did happen 65 million years ago? How was this extraordinary line created across the Earth and does it really hold the key to the death of the dinosaurs?With Simon Kelley, Head of Department in the Department of Earth Sciences, Open University, Jane Francis, Professor of Palaeoclimatology, University of Leeds; Mike Benton, Professor of Vertebrate Palaeontology in the Department of Earth Sciences, University of Bristol.

Melvyn Bragg and guests discuss Renaissance Mathematics. As with so many areas of European thought, mathematics in the Renaissance was a question of recovering and, if you were very lucky, improving upon Greek ideas. The geometry of Euclid, Appollonius and Ptolemy ruled the day. Yet within two hundred years, European mathematics went from being an art that would unmask the eternal shapes of geometry to a science that could track the manifold movements and changes of the real world. The Arabic tradition of Algebra was also assimilated. In its course it changed the way people understood numbers, movement, time, even nature itself and culminated in the calculus of Isaac Newton and Gottfried Leibniz. But how did this profound change come about? What were the ideas that drove it and is this the period in which mathematics became truly modern?With Robert Kaplan, co-founder of the Maths Circle at Harvard University; Jim Bennett, Director of the Museum of Science and Fellow of Linacre College, University of Oxford;

Melvyn Bragg and guests discuss perception: how the brain reacts to the mass of data continually crowding it. Barry Stein's laboratory at Wake Forest University in the United States found that the shape of a right angle drawn on the hand of a chimpanzee starts the visual part of the brain working, even when the shape has not been seen. It has also been discovered that babies learn by touch before they can properly make sense of visual data, and that the senses of smell and taste chemically combine to give us flavour.Perception is a tangled web of processes and so much of what we see, hear and touch is determined by our own expectations that it raises the question of whether we ever truly perceive what others do.What governs our perception of the world? And are we correct to distinguish between sight, sound, smell, touch and taste when they appear to influence each other so very much?With Richard Gregory, Senior Research Fellow in the Department of Experimental Psychology, Bristol University; David Moore, Dire

Melvyn Bragg and guests discuss 'dark energy'. Only 5% of our universe is composed of visible matter, stars, planets and people; something called 'dark matter' makes up about 25% and an enormous 70% of the universe is pervaded with the mysteriously named 'dark energy'. It is a recent discovery and may be only a conjecture, but it has been invoked to explain an abiding riddle of the cosmos: if the expansion of the universe is powered by the energy of the Big Bang, then why isn't the expansion slowing down over time as the initial energy runs down and the attractive force of gravity asserts itself? Scientists had predicted a Big Crunch as the logical opposite of the Big Bang, but far from retracting, the expansion of the universe is actually accelerating...it's running away with itself.How do we know that the universe is behaving like this and what's causing it? If dark energy is the culprit, then what is this elusive, though omnipresent entity?With Sir Martin Rees, Astronomer Royal and Professor of Cosmology a

Melvyn Bragg and guests discuss the history of Alchemy, the ancient science of transformations. The most famous alchemical text is the Emerald Tablet, written around 500BC and attributed to the mythical Egyptian figure of Hermes Trismegistus. Among its twelve lines are the essential words - “as above, so below". They capture the essence of alchemy, that the heavens mirror the earth and that all things correspond to one another. Alchemy was taken up by some of the most extraordinary people in our intellectual development, including Roger Bacon, Paracelsus, the father of chemistry, Robert Boyle, and, most famously, Isaac Newton, who wrote more about alchemy than he did about physics. It is now contended that it was Newton’s studies into alchemy which gave him the fundamental insight into the famous three laws of motion and gravity.With Peter Forshaw, Lecturer in Renaissance Philosophies at Birkbeck, University of London, Lauren Kassell, Lecturer in the History and Philosophy of Science at the University of Ca

Melvyn Bragg and guests discuss the Cambrian period when there was an explosion of life on Earth. In the Selkirk Mountains of British Columbia in Canada, there is an outcrop of limestone shot through with a seam of fine dark shale. A sudden mudslide into shallow water some 550 million years ago means that a startling array of wonderful organisms has been preserved within it. Wide eyed creatures with tentacles below and spines on their backs, things like flattened rolls of carpet with a set of teeth at one end, squids with big lobster-like arms. There are thousands of them and they seem to testify to a time when evolution took a leap and life on this planet suddenly went from being small, simple and fairly rare to being large, complex, numerous and dizzyingly diverse. It happened in the Cambrian Period and it's known as the Cambrian Explosion.But if this is the great crucible of life on Earth, what could have caused it? How do the strange creatures relate to life as we see it now? And what does the Cambrian Ex

Melvyn Bragg and guests discuss the mind/body problem in philosophy. At the start of René Descartes' Sixth Meditation he writes: "there is a great difference between mind and body, inasmuch as body is by nature always divisible, and mind is entirely indivisible. For when I consider the mind, or myself in so far as I am merely a thinking thing, I am unable to distinguish many parts within myself; I understand myself to be something quite single and complete. Although the whole mind seems to be united to the whole body, I recognize that if a foot or an arm or any other part of the body is cut off nothing has thereby been taken away from the mind".This thinking is the basis of what's known as 'Cartesian dualism', Descartes' attempt to address one of the central questions in philosophy, the mind/body problem: is the mind part of the body, or the body part of the mind? If they are distinct, then how do they interact? And which of the two is in charge?With Anthony Grayling, Reader in Philosophy at Birkbeck, Univers

Melvyn Bragg and guests discuss the Second Law of Thermodynamics which can be very simply stated like this: "Energy spontaneously tends to flow from being concentrated in one place to becoming diffused and spread out". It was first formulated – derived from ideas first put forward by Lord Kelvin - to explain how a steam engine worked, it can explain why a cup of tea goes cold if you don't drink it and how a pan of water can be heated to boil an egg.But its application has been found to be rather grander than this. The Second Law is now used to explain the big bang, the expansion of the cosmos and even suggests our inexorable passage through time towards the 'heat death' of the universe. It's been called the most fundamental law in all of science, and CP Snow in his Two Cultures wrote: "Not knowing the Second Law of Thermodynamics is like never having read a work of Shakespeare".What is the Second Law? What are its implications for time and energy in the universe, and does it tend to be refuted by the exist

Melvyn Bragg and guests discuss the extraordinary mind of the psychiatrist Carl Gustav Jung. In 1907 Sigmund Freud met a young man and fell into a conversation that is reputed to have lasted for 13 hours. That man was the Swiss psychiatrist Carl Gustav Jung. Freud is celebrated as the great pioneer of the 20th century mind, but the idea that personality types can be 'introverted' or 'extroverted', that certain archetypal images and stories repeat themselves constantly across the collective history of mankind, and that personal individuation is the goal of life, all belong to Jung: "Your vision will become clear only when you look into your heart... Who looks outside, dreams. Who looks inside, awakens", he declared. And he also said "Show me a sane man and I will cure him for you".Who was Jung? What is the essence and influence of his thought? And how did he become such a controversial and, for many, such a beguiling figure?With Brett Kahr, Senior Clinical Research Fellow in Psychotherapy and Mental Health at

Melvyn Bragg and guests discuss the Higgs Boson particle. One weekend in 1964 the Scottish scientist Peter Higgs was walking in the Cairngorm Mountains. On his return to his laboratory in Edinburgh the following Monday, he declared to his colleagues that he had just experienced his 'one big idea' and now had an answer to the mystery of how matter in the universe got its mass. That big idea took many years of refining, but it has now generated so much international interest and has such an important place in physics that well over one billion pounds is being spent in the hope that he was right. It's the biggest science project on Earth; the quest to find the 'Higgs Boson', a fundamental constituent of nature that - if it does exist - has such a central role in defining the universe that it's also known as the God Particle.What is the Higgs Boson? Why is it so important to scientists and how are they planning to find it?With Jim Al-Khalili, Senior Lecturer in Physics at the University of Surrey; David Wark, Pro

Melvyn Bragg and guests discuss the dawn of the age of electricity. In Gulliver's Travels, published in 1726, Jonathan Swift satirised natural philosophers as trying to extract sunbeams from cucumbers. Perhaps he would have been surprised, or even horrified, by the sheer force of what these seemingly obscure experimentalists were about to unleash on society. Electricity soon reached into all areas of 18th century life, as Royal Society Fellows vied with showmen and charlatans to reveal its wonders to the world. It was, claimed one commentator, 'an entertainment for Angels rather than for Men'. Electricity also posed deep questions about the nature of life. For some it was the divine spark that animated all things, for others it represented a dangerous materialism that reduced humans to mere machines.But how did electricity develop in the 18th and 19th centuries? Why was it so politically contentious and how was it understood during the age in which it changed the world forever?With Simon Schaffer, Professor i

Melvyn Bragg and guests discuss the emergence of the world’s first organic matter nearly four billion years ago. Scientists have named 1.5 million species of living organism on the land, in the skies and in the oceans of planet Earth and a new one is classified every day.  Estimates of how many species remain to be discovered vary wildly, but science accepts one categorical point – all living matter on our planet, from the nematode to the elephant, from the bacterium to the blue whale, is derived from a single common ancestor. What was that ancestor?  Did it really emerge from a ‘primordial soup’? And what, in the explanation of evolutionary science, provided the catalyst to start turning the cycle of life?With Richard Dawkins, Charles Simonyi Professor of the Public Understanding of Science at Oxford University; Richard Corfield, Visiting Senior Lecturer at the Centre for Earth, Planetary, Space and Astronomical Research at the Open University; Linda Partridge, Biology and Biotechnology Research Council Prof

Melvyn Bragg and guests discuss the history of the most detailed number in nature. In the Bible's description of Solomon's temple it comes out as three, Archimedes calculated it to the equivalent of 14 decimal places and today's super computers have defined it with an extraordinary degree of accuracy to its first 1.4 trillion digits. It is the longest number in nature and we only need its first 32 figures to calculate the size of the known universe within the accuracy of one proton. We are talking about Pi, 3.14159 etc, the number which describes the ratio of a circle's diameter to its circumference. How has something so commonplace in nature been such a challenge for maths? And what does the oddly ubiquitous nature of Pi tell us about the hidden complexities of our world? With Robert Kaplan, co-founder of the Maths Circle at Harvard University, Eleanor Robson, Lecturer in the Department of History and Philosophy of Science at Cambridge University; and Ian Stewart, Professor of Mathematics at the University o

Melvyn Bragg and guests discuss Renaissance obsession with Magic. In 1461 one of the powerful Medici family’s many agents carried a mysterious manuscript into his master’s house in Florence. It purported to be the work of an ancient Egyptian priest-king and magician called Hermes Trismegistus. When Cosimo de Medici saw the new discovery, he ordered his translations of Plato to be stopped so that work could begin on the new discovery at once. Hermes promised secret knowledge to his initiates and claimed to have spoken with the spirits and turned base metal into gold. His ideas propelled natural magic into the mainstream of Renaissance intellectual thought, as scholars and magi vied to understand the ancient secrets that would bring statues to life and call the angels down from heaven.But why did magic appeal so strongly to the Renaissance mind? And how did the scholarly Magus, who became a feature of the period, manage to escape prosecution and relate his work to science and the Church?With Peter Forshaw, Lect