Explore the history and unique characteristics of water, including its composition discovered by Lavoisier. Learn about water's ability to store energy, its unusual behavior when cooled, and its importance for organic chemistry. Discover the role of water in biological processes and the mysteries of ice's structure.

In a programme first broadcast in 2013, Melvyn Bragg and his guests discuss absolute zero, the lowest conceivable temperature.  In the early eighteenth century the French physicist Guillaume Amontons suggested that temperature had a lower limit.  The subject of low temperature became a fertile field of research in the nineteenth century, and today we know that this limit - known as absolute zero - is approximately minus 273 degrees Celsius.  It is impossible to produce a temperature exactly equal to absolute zero, but today scientists have come to within a billionth of a degree.  At such low temperatures physicists have discovered a number of strange new phenomena including superfluids, liquids capable of climbing a vertical surface.With:Simon Schaffer Professor of the History of Science at the University of CambridgeStephen Blundell Professor of Physics at the University of OxfordNicola Wilkin Lecturer in Theoretical Physics at the University of BirminghamProducer: Thomas Morris

Melvyn Bragg and his guests discuss the life and work of the Victorian anthropologist and archaeologist Augustus Pitt-Rivers. Over many years he amassed thousands of ethnographic and archaeological objects, some of which formed the founding collection of the Pitt Rivers Museum at Oxford University. Inspired by the work of Charles Darwin, Pitt-Rivers believed that human technology evolved in the same way as living organisms, and devoted much of his life to exploring this theory. He was also a pioneering archaeologist whose meticulous records of major excavations provided a model for later scholars. With:Adam Kuper Visiting Professor of Anthropology at Boston UniversityRichard Bradley Professor in Archaeology at the University of ReadingDan Hicks University Lecturer & Curator of Archaeology at the Pitt Rivers Museum at the University of Oxford.Producer: Thomas Morris.

Melvyn Bragg and his guests discuss comets, the 'dirty snowballs' of the Solar System. In the early 18th century the Astronomer Royal Sir Edmond Halley compiled a list of appearances of comets, bright objects like stars with long tails which are occasionally visible in the night sky. He concluded that many of these apparitions were in fact the same comet, which returns to our skies around every 75 years, and whose reappearance he correctly predicted. Halley's Comet is today the best known example of a comet, a body of ice and dust which orbits the Sun. Since they contain materials from the time when the Solar System was formed, comets are regarded by scientists as frozen time capsules, with the potential to reveal important information about the early history of our planet and others.With:Monica Grady Professor of Planetary and Space Sciences at the Open UniversityPaul Murdin Senior Fellow at the Institute of Astronomy at the University of CambridgeDon Pollacco Professor of Astronomy at the University of WarwickProducer: Thomas Morris.

Melvyn Bragg and his guests discuss the history of crystallography, the study of crystals and their structure. The discovery in the early 20th century that X-rays could be diffracted by a crystal revolutionised our knowledge of materials. This crystal technology has touched most people's lives, thanks to the vital role it plays in diverse scientific disciplines - from physics and chemistry, to molecular biology and mineralogy. To date, 28 Nobel Prizes have been awarded to scientists working with X-ray crystallography, an indication of its crucial importance. The history of crystallography began with the work of Johannes Kepler in the 17th century, but perhaps the most crucial leap in understanding came with the work of the father-and-son team the Braggs in 1912. They built on the work of the German physicist Max von Laue who had proved that X-rays are a form of light waves and that it was possible to scatter these rays using a crystal. The Braggs undertook seminal experiments which transformed our perception of crystals and their atomic arrangements, and led to some of the most significant scientific findings of the last century - such as revealing the structure of DNA. With:Judith Howard Director of the Biophysical Sciences Institute and Professor of Chemistry at the University of DurhamChris Hammond Life Fellow in Material Science at the University of LeedsMike Glazer Emeritus Professor of Physics at the University of Oxford and Visiting Professor of Physics at the University of WarwickProducer: Natalia Fernandez.

Explore the history of Fermat's Last Theorem and the 350-year delay in proving it. Delve into Pythagoras' theorem and its practical applications. Learn about the lost work of an extraordinary mathematician and the contributions of various mathematicians to the theorem. Discover how a woman mathematician surpassed renowned mathematicians. Uncover the intrigue surrounding Fermat's last theorem and the connection between elliptic curves and modular forms. Finally, dive into Andrew Wiles' proof and its practical applications.

Melvyn Bragg and his guests discuss the cell, the fundamental building block of life. First observed by Robert Hooke in 1665, cells occur in nature in a bewildering variety of forms. Every organism alive today consists of one or more cells: a single human body contains up to a hundred trillion of them. The first life on Earth was a single-celled organism which is thought to have appeared around three and a half billion years ago. That simple cell resembled today's bacteria. But eventually these microscopic entities evolved into something far more complex, and single-celled life gave rise to much larger, complex multicellular organisms. But how did the first cell appear, and how did that prototype evolve into the sophisticated, highly specialised cells of the human body?With:Steve Jones Professor of Genetics at University College LondonNick Lane Senior Lecturer in the Department of Genetics, Evolution and Environment, University College LondonCathie Martin Group Leader at the John Innes Centre and Professor in the School of Biological Sciences at the University of East AngliaProducer: Thomas Morris.

Melvyn Bragg and his guests discuss game theory, the mathematical study of decision-making. First formulated in the 1940s, the discipline entails devising 'games' to simulate situations of conflict or cooperation. It allows researchers to unravel decision-making strategies, and even to establish why certain types of behaviour emerge. Some of the games studied in game theory have become well known outside academia - they include the Prisoner's Dilemma, an intriguing scenario popularised in novels and films, and which has inspired television game shows. Today game theory is seen as a vital tool in such diverse fields as evolutionary biology, economics, computing and philosophy. With:Ian StewartEmeritus Professor of Mathematics at the University of WarwickAndrew ColmanProfessor of Psychology at the University of LeicesterRichard BradleyProfessor of Philosophy at the London School of Economics and Political Science.Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the emergence of geology as a scientific discipline. A little over two hundred years ago a small group of friends founded the Geological Society of London. This organisation was the first devoted to furthering the discipline of geology - the study of the Earth, its history and composition. Although geology only emerged as a separate area of study in the late eighteenth century, many earlier thinkers had studied rocks, fossils and the materials from which the Earth is made. Ancient scholars in Egypt and Greece speculated about the Earth and its composition. And in the Renaissance the advent of mining brought further insight into the nature of objects found underground and how they got there. But how did such haphazard study of rocks and fossils develop into a rigorous scientific discipline?With:Stephen PumfreySenior Lecturer in the History of Science at Lancaster UniversityAndrew ScottProfessor of Applied Palaeobotany at Royal Holloway, University of LondonLeucha VeneerResearch Associate at the Centre for the History of Science, Technology and Medicine at the University of Manchester.Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the measurement of time. Early civilisations used the movements of heavenly bodies to tell the time, but even in the ancient world more sophisticated timekeeping devices such as waterclocks were known. The development of mechanical clocks in Europe emerged in the medieval period when monks used such devices to sound an alarm to signal it was the hour to pray, although these clocks did not tell them the time. For hundreds of years clocks were inaccurate and it proved hard to remedy the problems, let alone settle on a standard time that the country should follow. It was with the advent of the railways that time finally became standardised in Britain in the mid-19th century and only in 1884 that Greenwich became the prime meridian of the world. Atomic clocks now mark the passing of the days, hours, and minutes and they are capable of keeping time to a second in 15 million years. With:Kristen LippincottFormer Director of the Royal Observatory, GreenwichJim BennettDirector of the Museum of the History of Science at the University of OxfordJonathan BettsSenior Curator of Horology at the Royal Observatory, GreenwichProducer: Natalia Fernandez.