23 November 2011
The Nuclear Debate
In a departure from the usual pattern of Science Café meetings we held a debate with two speakers, one supporting and one opposing the motion that “this house believes that the risks involved in the generation of electricity by nuclear power make it unusable”. A vote was taken before the debate started which showed a clear majority in favour of the use of nuclear power. The intention was to see if opinion could be changed by the arguments put forward by the speakers.
Dr. Alister Scott, visiting Fellow in the Science and Technology Policy Research Unit of Sussex University, argued in favour of the motion. There are three main risks. Firstly the technology is so complex, with so many components closely interdependent, that it is impossible to ensure a completely safe system. Despite assurances from the nuclear industry that safety design and planning make the chance of an accident vanishingly small, there have still been four major incidents in the past 54 years: Windscale in the UK, Three Mile Island in the US, Chernobyl in the USSR and Fukushima in Japan. All technologies go wrong; failures in complex, interacting systems can lead to catastrophic consequences. Secondly there are security risks, not only from terrorism and political activism, but from lack of infrastructure investment. Nuclear power is inflexible and unable to respond to short term changes in the demand and supply of energy sources. Finally, the economic risks of very high construction and operating costs and the cost of a major accident are unsupportable. Only governments can carry such risks, and in doing so they distort the economics of the energy market by unfairly subsidising nuclear power. The combination of technology, security and economic risks make nuclear power unusable.
Dr Nigel Knee, Head of Nuclear Policy at EDF Energy, spoke against the motion. He addressed the issue of risks, arguing that we live in an uncertain world, and that those nuclear accidents that have occurred led to far fewer deaths than from other accidents, and from natural disasters. Modern nuclear power stations are much more reliable and safe. The main risk from not using nuclear power is to ignore the role it can play in the decarbonisation of energy supply as part of a diverse energy mix. The UK is now a net importer of natural gas, and its electricity generation is still dominated by the use of fossil fuels. Our energy consumption is predicted to rise from 363 TWh in 2010 to 470 TWh in 2030 while we are committed to reduce the fossil fuel component from 75% to 20%. The only way this can be achieved is by major investments in renewable sources, and in nuclear power. Dr Knee described his company’s current range of generating systems, and its plans for the future, in particular for two new nuclear stations at Hinkley Point in Somerset. His “nuclear vision” was for safe, reliable and sustainable nuclear power bringing maximum benefits in jobs, for business and with planning to mitigate its environmental impact.
A lively session of questions was followed by a second vote on the motion. The number still in favour of nuclear power was reduced, and there was a shift in opinion against nuclear power in those previously undecided. The numbers voting were:
Before the debate
After the debate
Pro nuclear
49
42
Anti-nuclear
16
26
undecided
12
6
26 October 2011
The mathematics of Jazz
Iain Houston
Science and art are responses to the ways humans observe, interact and are part of the things around them. There are other categories of human response but it is science and art many people seem keenest to link. I have often wondered why and, as an artist, am grateful to the Science Cafe for the wealth of expertise it bravely presents to a wide range of thinking audiences.
From the superficial grasp of science I have managed, it has become interesting to imagine what those who deal with science actually do when working. More difficult, it would appear for a great many of us, is to “picture” mathematics and its underpinning role; Iain Houston added to the pleasure I find in linking.
He and his fellow musicians played beautifully and exhibited the wonder we feel when humans interweave outside of the domestic. As one who began to leave the ‘wonder of Mathematics’ soon after ‘B O D M A S’ I was grateful to share with others the “Simplicity/difficulty” of Iain’s mathematical abstractions. Abstraction is probably the place where Jazz and Mathematics are happiest and probability is the “proposition of whose truth we are not certain.” What is certain is my love of Jazz.
Andrew Wallace - a personal view
28 September 2011
Scientific Medicine
Les Rose
Sherborne Science Café was given a fascinating insight into the world of ‘Big Pharma’ by Les Rose at the meeting on 28 September 2011. We were informed about the protocol for clinical trials that precedes a drug coming to market, reflecting aspects of John Le Carre’s novel The Constant Gardener.
It takes 10 years of testing, at an average cost of £500 million, before a new drug can be prescribed. 95% of new drugs do not get through the many hurdles to reach this stage, and of those that do 80% never make a profit. However it follows that the other 20% must do quite well!
We learned that clinical trials have 4 stages and 2 or 3 arms, often with placebos, to compare the new drug or treatment. They are rigorous and involve randomization of the treatment groups. Trials are “double-blinded” so that patients and investigators do not know which treatment they are receiving/administering. It is often necessary to pool results in patient groups from several countries. Expert statistical analysis is required at the design stage of a trial as well as in the assessment of the results
There are many problems in conducting a successful trial, and mistakes can occur. Thalidomide, the infamous tranquiliser, was never tested on pregnant women and had tragic effects when used in pregnancy. Drugs may act differently in different patients, when genetic variations may stop them being effective. However we must be grateful for the achievements of modern, scientific medicine. Our future and longevity will definitely be determined by the effectiveness of the pills we take. ’Medicine Men’ are even more powerful today than they were 5000 years ago!
27 July 2011
100 years of the Rutherford-Bohr atom
Dr Percy Seymour
What has a can of Danish beer to do with the foundation of modern physics? Percy Seymour, in a wide-ranging review of the development of our understanding of the sub-atomic world, explained that it was a fellowship paid by the Carlsberg company of Copenhagen that enabled the physicist Niels Bohr to come to England. His invitation to Manchester in 1912 by Ernest Rutherford began one of the most important collaborations in all of physics. In the previous year Rutherford and his colleagues Marsden and Geiger had carried out the experiment that demonstrated that the atom has a very dense, positively charged nucleus surrounded by electrons. This description replaced J J Thompson’s “plum pudding” model, where the positive and negative charges were uniformly distributed.
However, there were still observations that remained to be explained; in particular the discrete lines in the emission and absorption spectra from atoms at high temperature. The astrophysicist J W Nicholson had attempted to explain the observed spectral lines from gas clouds within nebulae. These had been ascribed to elements (nebulium and coronium) not seen on earth. Nicholson applied the ideas of quantum mechanics to the angular momentum of the atomic electrons, and Bohr extended this to all atoms. A model analogous to a solar system emerged, with electrons occupying orbits constrained by a number of rules. In variance to classical physics, electrons within atomic orbits do not radiate energy; energy is only emitted when an electron moves to an orbit nearer the nucleus, and absorbed when an electron is forced into a higher orbit. Using this “shell” model Bohr was able to explain the spectral lines from Hydrogen and a number of other singly ionised atoms. Although it has been improved and modified, the shell model is still useful as a basic explanation of atomic structure.
Further modifications of the model by Michelson and Sommerfeld explained the splitting of spectral lines in magnetic fields, and Pauli introduced the concept of electron spin. Later models of the atom became less intuitive and required much more sophisticated mathematics. De Broglie introduced the idea of duality, in which a particle can sometimes behave as a wave, and Schrodinger developed the branch of mathematics known as wave mechanics to describe the behaviour of electrons in atoms. Heisenberg revealed the limits of knowledge at the sub-atomic level by introducing the concept of uncertainty. Thus it is impossible to know both the position and momentum of a particle precisely, and by extension a perfect description of the physical world is impossible.
The ultimate success of quantum mechanics arose from the theoretical work of Dirac. By reconciling Einstein’s theory of relativity with Schrodinger’s equations Dirac predicted the existence of antimatter, and the phenomenon of electron spin. Subsequent observations confirmed Dirac’s predictions, and one of the most successful models in the whole of science was finally established. Quantum mechanics explains the chemistry of the elements, the structure of the atom and the behaviour of the atomic nucleus. What we have lost in the process is the comfort of absolute certainty.
22 June 2011
What shall we do when we run out of oil?
Prof Chris Rhodes
Prof Chris Rhodes is an independent consultant on energy and environmental matters and visiting professor at Reading University. He gave a very informative and sobering description of the situation facing us in finding enough oil to meet the growing world demand. Having described what oil is, its many uses and the trend in consumption, he presented data on the production from various sources. The peak in oil production was predicted mathematically by M King Hubbert (Shell) in 1956 to occur 40 years after the year of “Peak Discovery” and the prediction appears accurate. Future sources of oils will be more difficult and require more energy to extract.
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Oil, a fossil fuel, has other problems. The burning of oil contributes 3 billion tonnes of carbon to the atmosphere every year (40% of all carbon emitted by mankind) which may affect the climate.
The alternatives to oil were discussed, but each has accompanying problems. Hydrogen is a “clean” fuel, but very costly to produce. Nuclear energy has environmental objections, and far too few nuclear power stations are being built. Renewable sources such as wind power are unreliable, contribute a very small proportion of energy requirements and are resource-intensive to build. Bio-fuels require large amounts of land to grow the raw materials and divert resources from food production.
Some possible solutions were presents, including bio-fuel from algae and less energy intensive agriculture, but the basic conclusion was that at present there is no prospects of meeting the enormous demand for oil in the future. It will become increasingly expensive, and major changes in the way we live will be required, including a drastic programme of energy saving. A more localised, less demanding society is needed.
We were left with a quote from Charles Kingsley
“We act as though comfort and luxury were the chief requirements of life, when all that we need to make us really happy is something to be enthusiastic about
25 May 2011
The quest for antimatter
Dr Glenn Patrick
Antimatter is a subject often associated with some of the more bizarre science reports in the media and with science fiction. However, the subject was given a much more down to Earth approach by Dr Glen Patrick, a particle physicist from the Rutherford Appleton laboratory, who gave a lucid talk on the subject. Dr Patrick has worked on some of the largest particle accelerators in Europe, including the Large Hadron Collider at CERN in Geneva.
By way of introduction, he mentioned Rutherford’s discovery of the atomic nucleus, and he then went on to describe the Standard Model of Particle Physics. Although there had been speculations about the existence of antimatter at the turn of the nineteenth century, the first serious theory of antimatter came from the mathematical work of the English physicist Paul Dirac. Dirac set out to formulate a theory of quantum mechanics that was consistent with Einstein’s Special Theory of Relativity. However, this equation not only provided a much firmer theoretical basis for the understanding of atomic structure, it also showed that there could be particles with the same mass as the electron, but with a positive charge. Such particles were called positrons, and they we first detected by the American physicist Carl Anderson, in 1932, during his work on cosmic ray particles, which are continually bombarding our upper atmosphere from outer space.
The current theories of matter and antimatter require a symmetry between to the two types and this raises problems concerning theories about the origin of the universe. If matter and antimatter were created in equal quantities in the early universe, they should have annihilated each other very early on, so we should not, in reality, have the universe which we observe. The problem could be resolved if there was a breaking of the charge parity symmetry not long after the ‘Big Band’. Physicists have found evidence for the breaking of this symmetry, but a major area of research in this field is to study this symmetry breaking in more detail.
Dr Glen also discussed the basic ideas behind PET Scanners in hospitals where positron-electron annihilations in human tissues were used to map cancerous tumours.
The evening ended with many questions and a lively discussion.
27 April 2011
Beetle wings, and other folding things
Dr Robin Wootton, Exeter University
Sherborne Science Café was given a fascinating insight into the world of insects by Dr Robin Wootton. Unlike birds, insects have no muscles in their wings, so have developed an amazing variety of ways to fold and unfold them. This is necessary for the protection of the wings, and to perform subtle variations in flight. All this is made possible in the insect world by their unique modeling material ‘chitin’. This complex polysaccharide is so versatile that it can be formed into many structures from wings to mandibles.
Whereas dragonflies and their fossil predecessors have simple, unfolded wings, most other insect species have some form of folded wings. In order to achieve this insects have first to become experts in maths, and then to master the arts of Origami! Dr Wootton has been studying the problem of insect wing design for over 40 years. He treated us to some of the secrets by showing us the mechanics of folding which we then had to replicate with card provided. He then showed a fascinating range of origami models. It was great fun as we progressed to pop–up books, and 3D Murafold models from Japan.
During a lively session of questions we learned that hoverflies, the flight experts of the insect world, can accelerate at 2G in any direction. All agreed that we want to get Dr Wootton back to tell us more about the mechanics of insect flight.
23 March 2011
Prospects for defeating ageing altogether
Dr Aubrey de Grey
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Dr Aubrey de Grey is CSO of the SENS Foundation, a USA-based charity which funds research into regenerative medicine. He spoke on the prospects of extending healthy and active human lifespan within the foreseeable future. The processes of metabolism within cells eventually lead to damage, which in turn is expressed as the diseases of old age. Conventional geriatric medicine attempts to treat the symptoms and delay the effects, but fails to tackle the fundamental problems. Regenerative medicine attempts to restore tissues and organs to the state before the damage occurred by understanding the processes involved and devising suitable treatments. Using the analogy of repairing and maintaining a car, Dr de Grey advanced the thesis that a similar approach could extend human life.
Seven type of tissue damage have been identified. In order to significantly prolong active life all the damage processes must be dealt with. Dr de Grey outlined one process, the degradation of cholesterol, and described experiments to identify and reduce the breakdown products. The concept of longevity escape velocity (the rate at which rejuvenation therapies must improve to defeat the accumulating damage) was explained. With advancing technologies a gain in biological age of 30 years is possible within the near future. Computer simulations using fairly modest assumptions about the likely improvements in therapies show that much longer lifespans are possible. The first 1000 year old is probably less than 20 y younger than the first 150 year old!
During a lively discussion period the potential problems of a much larger, much older population were raised. What all these people would do, the demands on finite resources, the social implications and whether we would want to live to be 1000 were topics discussed.
23 February 2011
A physicist among the penguins
Professor Peter Barham Bristol University
This was the theme of Professor Peter Barham as he described his time as a physicist among the Penguins to the Sherborne Science Café at their monthly meeting. There are 17 different species of penguin and their same body plan can survive in a range of climatic conditions, from -70C in the Antarctic to + 40C in the Atacama desert in Peru. The largest of the range is the Emperor penguin at 3.0 m. and 40 kg, which is able to dive to the amazing depth of 830 m. Several species are in danger, mainly due to oil pollution and over-fishing of their staple diet, krill.
Complete with ‘cuddly’ visual aids of each species he described over 30 years of research, working mainly on the African penguin on Robben Island, South Africa. He has developed a new method of tagging them to record their numbers and movements. Rather than use attachment to their powerful ‘wings’, with which they swim through the water, they now record the coloured spots on their pectoral region, which conform to ‘Turing Patterns ‘.
We also heard of the Adelie penguins who like to build very tall nests made of pebbles. In fact the females of the species (those are the ones with muddy footprints on their backs!) will do absolutely anything to secure another pebble! It seems therefore, that the ‘oldest profession’ did not start with Homo sapiens?!
26 January 2011
The Planck Project
Dr Chris North - Cardiff University, School of Physics and Astronomy
Chris North started with a slide showing William Herschel’s diagram of the distribution of stars in our Milky Way Galaxy. He also spoke of the importance of the Andromeda Galaxy in establishing the distribution of Galaxies in our local cluster of Galaxies. He then moved on to discuss Edwin Hubble’s discovery of the expansion of the university, and this was followed by a diagram showing the various stages in the evolution of the universe after the ‘Big Bang’. He then moved on to discuss the discovery of the thermal remnants of the ‘Big Bang’ by Arno Penzias and Robert Wilson, the so called Cosmic Microwave Background Radiation, in 1964, and the first mapping of the overall distribution of this radiation by the satellite COBE (Cosmic Microwave Background Observer), which was launched by NASA in November 1989.
The rest of the talk was devoted to discussing two satellites launched together on 14 May 2009. Chris showed slides of the constructions of Planck and Herschel satellites, and their relative orbits with respect to that of our Earth. Planck was designed to image fluctuations of the Cosmic Microwave Background Radiation with unprecedented sensitivity and angular resolution. Herschel is opening a new window to study how the universe has evolved to become the universe which we see today. Dr North showed several animated and colourful slides of the most important results of these two missions.
At the end there was a lively string of questions from the floor.