Physics and Cosmology

Duration: 45 minutes
First broadcast: Thursday 25 March 2004

Melvyn Bragg and guests discuss the 30 year search to solve all the biggest questions in physics. At the end of the last century, brave voices were predicting that all the big questions of physics were on the verge of being answered by a Theory of Everything. The disparity between the physics of the very small would finally be reconciled with the very large, and the four forces of nature would finally be united with a single set of equations. It was suggested that with such a theory we might solve the riddle of black holes, unlock the secrets of the Big Bang, probe other universes and even uncover the mystery of travelling through time. But Stephen Hawking, who once said that with a Theory of Everything “we would know the m mind of God”, has changed his mind and now says that it may not be possible after all.

So what are the prospects for a Theory of Everything? Why do we need one? How do we get one? And what would it mean if we did?

With Brian Greene, Professor of Physics and Mathematics at Columbia University and author of The Fabric of the Cosmos; John Barrow, Professor of Mathematical Sciences at the University of Cambridge and author of The Constants of Nature; Dr Val Gibson, particle physicist from the Cavendish Laboratory and Fellow of Trinity College, Cambridge

http://www.bbc.co.uk/programmes/p004y24b

Duration: 45 minutes
First broadcast: Thursday 27 March 2003

Melvyn Bragg and guests discuss the life cycle of stars. In his poem Bright Star John Keats wrote, “Bright Star, would I were steadfast as thou art”. For Keats the stars were symbols of eternity- they were beautiful and ordered and unchanging – but modern astronomy tells a very different story. Stars, like everything else in the universe, are subject to change. They are born among vast swirls of gas and dust and they die in the stunning explosions we call supernovae. They create black holes and neutron stars and, in the very beginning of the universe, they forged the elements from which all life is made. But how do stars keep burning for millions of years, why do they self-destruct with such ferocity and what will happen to the universe when they all go out?

With Paul Murdin, Senior Fellow at the Institute of Astronomy, Cambridge; Janna Levin, Advanced Fellow in Theoretical Physics in the Department of Applied Mathematics & Theoretical Physics at the University of Cambridge; Phil Charles, Professor of Astronomy at Southampton University.

http://www.bbc.co.uk/programmes/p00548w8

Duration: 45 minutes
First broadcast: Thursday 16 May 2002

Melvyn Bragg examines whether world is a fundamentally chaotic or orderly place. When Newton published his Principia Mathematica in 1687 his work was founded on one simple message: Nature has laws and we can find them. His explanation of the movements of the planets, and of gravity, was rooted in the principle that the universe functions like a machine and its patterns are predictable.

Newton’s equations not only explained why night follows day but, importantly, predicted that night would continue to follow day for evermore. Three hundred years later Newton’s principles were thrown into question by a dread word that represented the antithesis of his vision of order: that word was Chaos.

According to Chaos Theory, the world is far more complicated than was previously thought. Instead of the future of the universe being irredeemably fixed, we are, in fact, subject to the whims of random unpredictability. Tiny actions can change the world by setting off an infinite chain of reactions: famously, if a butterfly flaps its wings in Brazil – it could cause a tornado in Berlin.

So what’s the answer? Is the universe chaotic or orderly? If it’s all so complicated, why does night still follow day? And what is going on in that most complex machine of all – the brain – to filter and construct our perception of the world?

With Susan Greenfield, Senior Research Fellow, Lincoln College, Oxford University; David Papineau, Professor of the Philosophy of Science, Kings College, London; Neil Johnson,University Lecturer in Physics at Oxford University.

http://www.bbc.co.uk/programmes/p00548f6

Duration: 45 minutes
First broadcast: Thursday 02 May 2002

Melvyn Bragg examines the physics of reality. When Quantum Mechanics was developed in the early 20th century reality changed forever. In the quantum world particles could be in two places at once, they disappeared for no reason and reappeared in unpredictable locations, they even acted differently according to whether we were watching them. It was so shocking that Erwin Schrodinger, one of the founders of Quantum Theory, said “I don’t like it and I’m sorry I ever had anything to do with it.” He even developed an experiment with a cat to show how absurd it was.

Quantum Theory was absurd, it disagreed with the classical physics of Newton and Einstein and it clashed with our experience of the everyday world. Footballs do not disappear without reason, cats do not split into two and shoes do not act differently when we are not looking at them. Or do they? Eighty years later we are still debating whether the absurd might actually be true.

But why are features of quantum physics not seen in our experience of everyday reality? Can the classical and quantum worlds be reconciled, and why should reality make sense to us?

With Roger Penrose, Emeritus Rouse Ball Professor of Mathematics, Oxford University; Fay Dowker, Lecturer in Theoretical Physics, Queen Mary, University of London; Tony Sudbery, Professor of Mathematics, University of York

http://www.bbc.co.uk/programmes/p00548dl

Duration: 45 minutes
First broadcast: Thursday 07 February 2002

Melvyn Bragg and guests discuss the shape of the universe. In the Beginning, runs one account, was the Big Bang. All matter in existence today originated around 13 billion years ago in a phenomenally hot, extraordinarily condensed primordial atom that exploded with incredible force. Hydrogen and helium were shot across the firmament, gravity caused the gases to condense into clouds and in these clouds the first stars were formed, then galaxies came and more galaxies in clusters, onwards and outwards, ever expanding. It is still expanding, runs the orthodox account, and may even be speeding up. It is still creating new galaxies and it continues to colonise more and more of infinite space, despite the fact that it is supposedly infinite itself.

So, if our universe is expanding, what is it expanding into? If it is already infinite how can it be getting any bigger? And is there really only one?

With Sir Martin Rees, Royal Society Research Professor in Astronomy and Physics, Cambridge University; Julian Barbour, Independent Theoretical Physicist; Janna Levin, Advanced Fellow in Theoretical Physics at the University of Cambridge

http://www.bbc.co.uk/programmes/p0054880

Duration: 45 minutes
First broadcast: Thursday 05 July 2001

Melvyn Bragg discusses the origin of the Earth. Ideas used to be very clear about its origins. Bishop Ussher, in 1654 arrived at an exact figure and specified it in his work Annalis Veteris et Novi Testamenti: He deduced that work on Planet Earth began at exactly 9am, on Monday 23rd October 4004 BC. The date was then printed in the margin of The Bible and preached from the pulpit, and right up to the nineteenth century to the left of ‘In The Beginning…’ was specified ‘Before Christ 4004’.

Christian believers thought the creation story was solid as a rock…until the geologists arrived. First Hutton, then Smith, and then Lyell smashing away at orthodox belief in a way that made poor Ruskin quail, but in doing so they created a science.

With Simon Winchester, author of The Map That Changed the World: the Tale of William Smith and the Birth of A Science; Cherry Lewis, geologist and author of The Dating Game: One Man’s Search for the Age of the Earth; John Cosgrove, Structural Geologist from the Royal School of Mines at Imperial College, London.

http://www.bbc.co.uk/programmes/p00547hl

Duration: 45 minutes
First broadcast: Thursday 12 April 2001

Melvyn Bragg and guests discuss Black Holes. They are the dead collapsed ghosts of massive stars and they have an irresistible pull: their dark swirling, whirling, ever-hungry mass has fascinated thinkers as diverse as Edgar Allen Poe, Stephen Hawking and countless science fiction writers. When their ominous existence was first predicted by the Reverend John Mitchell in a paper to the Royal Society in 1783, nobody really knew what to make of the idea – they couldn’t be seen by any telescope. Although they were suggested by the eighteenth century Marquis de Laplace and their existence was proved on paper by the equations of Einstein’s General Theory of Relativity, it was not until 1970 that Cygnus X 1, the first black hole, was put on the astral map.

What causes Black Holes? Do they play a role in the formation of galaxies and what have we learnt of their nature since we have found out where they are?

With the Astronomer Royal – 2001 Sir Martin Rees, Professor of Physics and Astronomy at Cambridge University; Jocelyn Bell Burnell, Professor of Physics at The Open University; Professor Martin Ward, director of the X-Ray Astronomy Group at the University of Leicester.

http://www.bbc.co.uk/programmes/p00547f4

Duration: 45 minutes
First broadcast: Thursday 22 February 2001

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.

http://www.bbc.co.uk/programmes/p00547c4