Lecture delivered at the annual meeting of the Royal Society of NSW, the Australian Nuclear Association, the Nuclear Panel of Engineers Australia, and the Australian Institute of Energy.

"Counting atoms for a living"

Dr Andrew Smith, ANSTO

Wednesday 7 March 2012 at 6 pm

Hamilton Room, Trade & Investment Centre, Industry & Investment NSW, Level 47, MLC Centre, 19 Martin Place, Sydney

Meeting report by Donald Hector

Andrew Smith counts cosmogenic radionucleides for a living! These are radioactive cosmic rays (or, more accurately, cosmic particles) most of which are generated in the Sun and the far reaches of the universe. The facilities at ANSTO users accelerator mass spectrometry (AMS) which is an assembly of tandem accelerators to detect rare isotopes of intermediate half-life.

Cosmic rays were discovered in 1904. They are energetic particles that impinge upon the Earth's atmosphere – about 90% are protons, 10% are helium nuclei (alpha particles) and less than 1% are heavier" nuclei. They are generated by the Sun, supernova and what astronomers refer to as "unknown events". When these particles hit the Earth's atmosphere and collide with other molecules, the products of these collisions can be observed and measured.

One of the applications of this technology is in carbon-dating. Carbon-dating technology relies on the fact that the atmospheric concentration of the 14C, the radioactive isotope of carbon, is constant with about 7.5 kg being produced in the atmosphere every year. While an organism is alive, it is in equilibrium of the atmosphere. When it dies the "clock" starts because 14C update ceases and radioactive decay gradually reduces the 14C concentration. The older technology is radiometry which is a passive technique that requires a relatively large sample (up to several grams) but using AMS (the ANSTO equipment uses the 2 MV STAR accelerator) is an "active" only requires a much smaller sample of around 0.1 mg.

One area of particular interest for Dr Smith and his team is using is highly sensitive analytical technique to examine the polar sheet in Antarctica. As it falls, snow traps atmospheric gas and particles and once the ice has accumulated to it thickness of 50-100 m, the air pockets are closed off, trapping the gas. To investigate theories relating to climate change, establishing historical concentrations of greenhouse gases is of particular interest. Carbon dioxide, methane and nitrous oxide (these three constitute only about 0.1% of the atmosphere) are trapped in the bubbles in the ice. Both natural sources of methane (termites, geologically produced methane, clathrates – these are methane molecules trapped in a cage of water molecules due to very high pressure and are found extensively in deep parts of the ocean – and anaerobic decay) and anthropogenic sources (landfills, livestock, rice cultivation, and waste water treatment) each has its own unique signature of carbon isotopes.

The experimental work being done in ANSTO over the last several years has been drilling down to extract cores from ice which has been deposited over several thousand years. Large quantities of ice are needed to get even the tiny samples needed for analysis (Dr Smith's recent expedition to the area near Casey base collected 7½ tons of ice). Once the samples go through a very careful preparation process and are analysed (including corrections for cosmic ray generation of 14C and the changes in 14C concentration caused by nuclear testing in the 1950s and 1960s when its concentration doubled) some very interesting information emerges. For example, historically there have been some very sharp changes in methane concentration. This could be due to clathrates releasing their methane in previous eras. If so, this indicate a major problem should global warming cause large methane releases either from clathrates or peat bogs as permafrost melts.

Another area of investigation that ANSTO is pursuing is whether there is a connection between sunspot activity and climate change. Historical astronomical records suggest that during the Maunder minimum (a period that has been described as "a mini ice age" in Europe from about 1635 to 1700) sunspot activity was unusually low. The first step is to measure the ratio of 7Be to 10Be which is well correlated to sunspot activity. This investigation is very complex and will have some years to run while such issues as beryllium transfer through the ice sheet needs to be understood. Dr Smith's team is at the cutting-edge of climate change research and is just one example of ANSTO's unique contribution to world-leading science.

"The influence of media on scientific research"

Mark Scott AO, Managing Director of the ABC, and Professor Jill Trewhella FRSN, Deputy Vice-Chancellor (Research) at the University of Sydney

Wednesday 4 April 2012 at 6.30 pm

Powerhouse Museum, Ultimo

Meeting report by Donald Hector

The Society's second annual Forum was held on Wednesday 4 April at the Powerhouse Museum. The discussion was between Mark Scott AO, Managing Director of the ABC and Professor Jill Trewhella FRSN, Deputy Vice Chancellor, Research and Innovation at Sydney University. The topic of the discussion was "The influence of media on scientific research". The forum was moderated by Robyn Williams AM of the ABC.

Mark pointed out that the role of national broadcasters (originally established to produce programmes that commercial companies could not or would not) has changed very significantly. The internet has made available thousands of TV and radio stations worldwide. The consumer is flooded with content. Gone are the days when listeners needed a licence – now all that is necessary is an internet connection. Nor are there barriers to entry for broadcasters. There are over 200 million web-sites worldwide and 60,000 blogs are introduced to the internet every day.

The role of the ABC is now even more important than it was formerly. It now provides a "town square" for content and opinion. It provides a broad plurality of views. Whereas the challenge for science is the narrowness of focus of much research is, the ABC provides a place where there is breadth not narrowness of interest. The gap between the ABC and content providers is growing every day due to the challenge facing commercial providers in delivering a profit in a rapidly changing media sector. The challenge for scientists is to become effective communicators and, particularly, to cultivate interest among journalists.

Jill said how important it was to have institutions like the ABC that produce quality content and encourage public education and debate. The key roles of the media are to educate, to inspire and to promote public discourse, particularly as the world faces critical issues, not least the state of the natural world.

Nonetheless it is regrettable that the media often confuse opinion, fact and belief. Too much of the current debate focuses on belief. But belief is not important in many issues – what is important are matters of fact. This is particularly significant in major issues such as health and climate change where scientific knowledge is important. For example, in health investment in research is generally seen as overwhelmingly good. And it probably is but what about the unavoidable trade-offs in research in other areas? It is also regrettable that advertising is a major influence on public opinion and political processes.

Robyn then moderated a discussion that included questions from the audience and covered such issues as the "priesthood status" of peer-review, the polarisation of public opinion, climate change, the state of critical argument in Australia and the necessity for the scientists to produce a compelling story in order to engage the media.

The Forum was broadcast on ABC Radio National's Big Ideas on Thursday 17 May 2012: click broadcast to download the programme.

"Belief in science"

Professor John White CMG FAA FRS, Australian National University

Friday 26 November 2010 at 5.30 pm

Lecture Theatre 1, Merewether Building, University of Sydney

The achievements of science in the last 400 years have been of great benefit to humanity and are appreciated widely. Less well understood is how personal attributes of awareness, excitement, frustration and recognition of beauty are central to successful science. These very human qualities play a role in making discoveries. Scientists' optimism, suspended disbelief, and a reliance on empiricism are as much part of the scientific method as clear logic. Science requires absolute honesty and care about conclusions to be believable. Science is not autonomous and the sometimes necessarily tentative opinions are often incomprehensible and even unacceptable to the public – we must do better in explaining! Professor White's lecture will also examine some of his recent work on the structure and function of industrially valuable explosive emulsions – understood by the novel neutron scattering methods of 'contrast variation' pioneered in his research.

John White is currently Professor of Physical and Theoretical Chemistry at the Research School of Chemistry at the Australian National University. Graduating from Sydney University, he went to Oxford University on an 1851 scholarship in 1959. He became a Research Fellow of Lincoln College before finishing his DPhil and an official Fellow of St John's College Oxford in 1963. He is one of the discoverers of isotopic contrast variation in neutron scattering – which is currently used worldwide for understanding the structure of "soft matter".

"Powering the US grid from solar and wind"

Dr David Mills, co-founder of Ausra, Inc.

Wednesday 3 November 2010 at 7 pm

Conference Room 1, Darlington Centre, University of Sydney

Solar and wind are our two largest energy resources and are well distributed globally. In these respects, they are ideal to re-power humanity with little climate or political impact. Some say that such a strategy is not practical because the solar resource disappears at night and each wind generator can be highly variable in output. However, the impact of already commercially available solar thermal storage technology, together with the overlap effects of wind energy from many sites may prove otherwise.

The first example used is the USA 2006 electrical load calculated on an hourly basis from government data and the second is a total energy supply scenario. A high voltage DC grid backbone (commercially available today) is assumed to allow full access of delivered power to all parts of the country. National wind and solar output are calculated hourly using government resource data. The initial results of the analysis are presented together with a discussion of the roles of solar and wind in such a new system, in comparison to conventional baseload/peaking thinking.

The talk will begin with an update of Dr Mills' company's activities in the United States since his leaving Sydney in early 2007, followed by an update of today's solar technology. The main part of the talk describes private work in progress by the author and his colleagues in the United States to take a first look at the feasibility of powering the United States energy system entirely from wind and sun by mid-century.

Dr Mills is the former Head of the Solar Energy Group at the University of Sydney and past President of the International Solar Energy Society. He is the co-founder and former chairman of the SHP and Ausra companies.

"Transit of Venus 2012 - what we and others saw"

Dr. Andrew Jacob, Assistant Curator, Sydney Observatory

Wednesday 6 June 2012 at 6.30 pm

Sydney Observatory, Observatory Hill, Sydney

Meeting report by Donald Hector

Early in the 17th century, Johannes Kepler predicted that every 120 years or so Venus would pass between the Earth and the Sun and on each occasion, there would actually be two transits about seven years apart. This was a particularly important prediction: Kepler's third Law had provided the means to accurately calculate of the relative distances of each of the planets from the sun but there was no way to determine the absolute distance between them. By observing a transit of Venus from different points on the Earth, observing the times at which the transits start and finish and the exact location of the observation it is relatively simple to calculate the absolute distance between the Earth and Sun (referred to as one Astronomical Unit). From Kepler's third Law it is then possible to calculate the distance of the other planets from the sun but, more importantly, it then enables the calculation of distant astronomical bodies using the Astronomical Unit as a baseline.

The Society was fortunate to be able to mark the transit of Venus at the Sydney Observatory with a talk given by Dr Andrew Jacob, the Observatory's assistant curator. Not only is the transit of Venus an important and rare astronomical event, astronomy and, in particular, the transit of Venus, play and important part in both the history of Australia and history of the Society.

The first predicted transit was in 1631 but there is no record of any successful observation is being made. The next, in 1639, was observed by Jeremiah Horrocks who was able to calculate the Astronomical Unit to an accuracy of about 50%. The next pair of transits were in 1761 and 1769. Lieutenant James Cook was ordered to sail to Tahiti to observe the 1769 transit which he did successfully and the rest, as they say, is history.

The next pair of transits in the 19th century (1874 and 1882) were observed using much more sophisticated instruments, including photography and these observations enabled very precise estimates of the Astronomical Unit.

The first of the 21st-century transits in 2004 was noted as an interesting phenomenon but not of any particular scientific importance. However, in the few years between 2004 and the 2012 transit, the discovery of hundreds of "exo-planets" (planets orbiting far-away stars) led astronomers to realise that precise observations of the phenomena caused by the transit of Venus could allow a much more precise and detailed characterisation of exo-planets.

It is notable that the Royal Society of NSW traces its origins to 1821 when the Philosophical Society of Australasia invited the Governor, Sir Thomas Brisbane, to become its first president. Brisbane was a keen astronomer and made important contributions to the science both in Australia and when he returned to Scotland.

"Is the climate right for nuclear power?"

Dr Ziggy Switkowski, Chair of the Australian Nuclear Science and Technology Organization

Wednesday 6 October 2010 at 7 pm

Conference Room 1, Darlington Centre, University of Sydney

The world is experiencing a strong warming trend believed to be driven by greenhouse gas emissions associated with the burning of fossil fuels for energy production. Australia's demand for electricity, and energy in general, is expected to double by 2050. The challenge is to moderate and meet this growing demand in an environmentally responsible way. Nuclear power is already widely used around the world and the debate for its deployment in Australia is well under way.

This presentation will review the nuclear fuel cycle in the context of low emission energy technology and point to the potential role of nuclear power in Australia's energy and climate change strategy.

Dr Ziggy Switkowski is the Chair of the Australian Nuclear Science and Technology Organization. He is also a non-executive director of Suncorp, Tabcorp and Healthscope, and Chair of Opera Australia. He is a former chief executive of Telstra, Optus and Kodak (Australia).

In 2006 he chaired the Prime Minister's Review of Uranium Mining, Processing and Nuclear Energy which returned nuclear power to the country's strategic debate. He has a PhD in nuclear physics from the University of Melbourne and is a Fellow of the Australian Academy of Technological Sciences and Engineering.

"Autoimmune diseases: obesity, nutrition, exercise and eating disorders: what shape are Australians in?"

Professor Ian Caterson AM, Boden Professor of Human Nutrition, Sydney Medical School, University of Sydney

Wednesday 4 July 2012 at 6.30 pm

Union, University and Schools Club, 25 Bent Street, Sydney

Meeting report by Donald Hector

At 1201st Ordinary General Meeting of the Society held at the Union University and Schools Club on Wednesday 4 July 2012, Professor Ian Caterson AM talked about the serious obesity epidemic that confronts Australia. This is not confined to Australia – it is a major health problem all developed countries and increasing alarmingly in the developing world, due to the low cost and ready availability of high-energy foods.

Professor Caterson discussed how the epidemiology involved. From the time of World War II when there was worldwide food rationing to the present, where there is generally a surplus of food, average weight has consistently increased. Currently, young adults are gaining, on average, 1 kg per year. The problem is not how much you weigh, rather it is how fat you are. More particularly the problem is how much visceral fat you have (visceral fat sits around the organs inside the abdominal cavity). Unfortunately for many of us "the fatter you are, the younger you die". A good indicator of obesity due to visceral fat is body-mass index (BMI), defined as your mass in kilograms divided by the square of your height in metres. Normal BMI is in the range of 18.5-24.9. A BMI in the range of 25-29.9 is considered to be pre-obese and a BMI of over 30 is considered to be obese. In Australia, 62% of men and about 50% of women have a BMI greater than 25.

Obesity is implicated in a wide range of debilitating disorders: cardiovascular disease, diabetes, sleep apnoea, hypertension, cancer and infertility (the average BMI of women enrolled in fertility programmes is 32. Losing 6 kg in weight increases fertility fifteen-fold).

At a BMI of about 25 (which is about the median in Australia) the biggest health risk is developing diabetes. Professor Caterson gave interesting case of Sumo wrestlers. They eat a high fat diet (in excess of 6,000 calories per day) but they are very strong and very fit. But when they stop fighting, within a year, 35% of them have developed diabetes and many die of heart disease in their 40s. While they are fit all their weight is outside their abdominal cavity but when they stop fighting and lose their fitness, their visceral fat increases rapidly.

Professor Caterson discussed the impact of this major health issue in terms of "disability-adjusted life-years lost". This is an indicator used by the World Health Organisation that combines into a single measure the debilitating effects of serious disease and mortality. The bad news is that if you smoke, are obese, and you are physically inactive you can look forward to losing about 14 years of good-quality life. But the news was not all bad.

In epidemiological terms, for every kilogram you lose, your death rate decreases by 6%. Changing diet can have a big impact. Eating slightly smaller portions, increasing protein, reducing saturated fat intake (replacing it where possible with monounsaturated fats, such as olive oil), increasing dietary fibre, eating fresh fruit and vegetables and getting regular exercise (ideally, one-two hours a day) can have a relatively quick and significant impact on BMI and overall health.

"Long-term changes in solar activity – including the current Grand Minimum"

Ken McCracken, Jellore Technologies and Senior Research Associate, University of Maryland

Wednesday 1 September 2010 at 7 pm
Conference Room 1, Darlington Centre, University of Sydney

The sunspot record since Galileo's time, and the cosmogenic nuclides ¹⁰Be (in ice cores) and ¹⁴C (in tree rings) show that the degree of activity of the Sun has varied greatly over time. The solar activity, manifested by the occurrence of sunspots, solar flares, and coronal mass ejections may be quite high, as it has been since 1946; and was during Roman times, or very small as during the Maunder Minimum (1645-1715); the Dalton Minimum (1810-20) or the Gleissberg Minimum of 1900-10. In the first part of the lecture, the speaker will discuss his recent studies with Swiss colleagues of the last 10,000 years of ¹⁰Be data from the Arctic and Antarctic that shows that the Sun has exhibited a number of persistent periodicities in solar activity, the most important being of duration 2300yr, 210yr, ~85yr, and the well known 11/22 year solar cycle. He will also outline the last 30 years of satellite data that show that the solar irradiance varies by ~0.1% over the 11 year solar cycle.

Against that background, he will then describe the substantial reduction in solar activity that commenced in 2006. Since then, the sunspot behaviour has been similar to that during the Dalton minimum (1810-20). The interplanetary magnetic fields have been lower than at any time during the space age, and the cosmic radiation intensities are well above those at any time during the past 60 years. The solar irradiance has decreased well below that observed in the previous 30 years. The evidence indicates that the magnetic properties of the Sun are now very different from those at any time in the "Space Age". Based on the 10,000 year ¹⁰Be record, he will speculate that the Sun will remain relatively inactive (and cool) for the next 20 years, and it will then resume a steadily increasing state of activity until it reaches a peak of the Hallstatt (2300 year) cycle ~200 years in the future.

Ken McCracken has had a long and varied life as a scientist, technologist, and contrarian. Starting his research career in Tasmania and New Guinea in the 1950s, he was then deeply involved in the early days of the US space program for seven years while at the Massachusetts Institute of Technology and the University of Texas. He designed and built scientific instruments that were flown on seven spacecraft that went to the orbits of Mars and Venus in the 1960s to provide the information needed to protect the US astronauts from being killed, or losing their virility, en route to the Moon. Following a professorship at the University of Adelaide, CSIRO appointed him to inaugurate a new research laboratory to improve geophysical exploration for minerals in the harsh Australian environment. Moving to the Southern Highlands in 1989, he operated a consultancy providing scientific advice to the mining industry. Over the past decade he and his Swiss, US, and Australian colleagues have used results from ice cores from Greenland and Antarctica to understand how the Sun has waxed and waned in activity over the past 10,000 years, and how this has paralleled the twenty two little ice ages, and many warming periods in the Earth's climate over the past 10,000 years. With his wife Gillian, he owns and operates the 850 acre beef breeding property "Jellore" in High Range.

"The accelerating universe"

Professor Brian Schmidt

Thursday 19 July 2012

Professor Schmidt took us on a fascinating journey of astronomy and cosmology, describing the work that he and his colleagues have done over the last two decades and where it fits in our understanding of the nature of the universe.

To establish a reference framework, we were taken on a quick tour of the universe using the speed of light as a ruler (the Moon is less than two light seconds from us. The Sun is 8 light minutes away. The nearest star, Alpha Centauri, is 4.3 light years away. We are 30,000 light years from the centre of our galaxy, the Milky Way. The nearest galaxy, Andromeda, is 2 million light years from us. The cosmic ray background establishes that the age of the universe is about 13.7 billion years, with the Hubble telescope being able to detect objects 12 billion light years away).

Although astronomy is one of the oldest sciences, modern cosmology had its beginnings in the 19th and 20th centuries when techniques such as spectral analysis began to be applied to light from the skies. Of particular importance was phenomenon known as the Doppler effect – objects that are moving towards us have their light shifted towards the blue end of the spectrum, while objects moving away have their light shifted to towards red. By analysing the spectra of galaxies, in 1916, Vesto Slipher found that all galaxies he observed were shifted towards red and therefore were moving away from us. The conclusion from this was that the universe is expanding.

Einstein's special theory of relativity published in 1907 proposed that acceleration due to gravity and acceleration due to motion are equivalent. This led to his general theory of relativity and the notion that space is curved. The solution to Einstein's equations are dynamic, implying that the universe should be in motion. To avoid the conclusion that the universe was expanding, Einstein introduced a "fudge factor" called the cosmological constant (Einstein later referred to this as his greatest blunder!).

One conclusion from the concept of an expanding universe is that at one point must have been a big bang. Observations suggest that the age of the universe could be as young as 9 billion years if its expansion was slowing due to gravity but this is contrary to observations that the oldest stars appear to be at least 12 billion years old.

Not only was Brian Schmidt interested in solving this problem and determining the age of the universe but he wanted to understand what its eventual fate might be. In the 1990s, by observing faintness/brightness plotted against high/low red shift it had been found that supernovae appeared to have very constant brightness and therefore could be used as a standard "candle". (It was later found that this was not quite so but further work to better understand Type 1A supernovae allowed for corrections that gave a very good correlation.)

Improved digital detection technology and data processing capability in the 1990s set the stage for major advances in astronomy. Many more supernovae could be observed and this gave the team led by Brian (whose area of specialisation was data processing) to study many high-resolution images and by tracking these images and filtering out background noise, to find supernovae candidates for much more detailed analysis. Brian's team found that distant supernovae were outside the range expected for a universe whose expansion was slowing. Detailed analysis of their data suggested that the expansion of the universe was in fact accelerating. This was contrary to the mainstream view of physicists at the time and, indeed was contrary to the findings of another team using a different approach to analysing the data. Professor Schmidt's team published their work and in 2011 were awarded the Nobel Prize.

The notion of a universe whose expansion is accelerating poses some interesting questions for cosmologists, not the least of which is what could be pushing it apart? Einstein's theory allows for the concept of "dark energy". The data from analysis of Type 1A supernovae can be explained if the forces are assumed to be about 30% "pull" from gravity and about 70% "push" from dark energy. For the universe to be flat (and an analysis of the background radiation of the universe shows that indeed it is flat, that is, the universe is not closed and it is not open), 27% of the universe would need to be matter and 73% would need to be dark energy. But the problem is that this is much more matter than appears to exist. The solution to this currently most favoured by cosmologists is the concept of "dark matter" - matter that we cannot see. And it is no small amount - less than 5% of all matter is thought to be observable.

Professor Schmidt concluded his lecture with some long-range forecasts for the future of the universe. In some places, gravity will win and matter will merge; in others, space will accelerate faster and light from those areas will never reach us. There could even be a "big rip". In this scenario, a few million years before the end, gravity would be too weak to hold the Milky Way and other galaxies together. Our solar system would become gravitationally unbound, the stars and planets would be torn apart and at the very end, individual atoms would be ripped apart.

"The dynamic brain: modeling sleep, wake, and activity in the working brain"

Professor Peter Robinson, University of Sydney

Wednesday 4 August 2010 at 7 pm

Conference Room 1, Darlington Centre, University of Sydney

The brain's activity varies around the clock in response to stimuli, light inputs, and the buildup and clearance of sleep-promoting chemicals - somnogens. Signatures of brain activity have been observed for over a century and are widely used to probe brain function and disorders, often via the electroencephalogram (EEG) recorded by electrodes on the scalp, or through functional magnetic resonance imaging (fMRI), which measures a combination of blood volume and deoxygenation. Here, a quantitative physiologically based model of the working brain is described that responds correctly to the day-night cycle, somnogens, caffeine and pharmaceuticals, and generates activity in the cortex consistent with brain imaging measurements. Successful applications to numerous experiments are described, including EEGs, seizures, sleep deprivation and recovery, fatigue, and shift work. Aside from its scientific uses, this working brain model is currently finding clinical and industrial applications to brain function measurement and to prediction and monitoring of alertness.

Peter Robinson received his PhD in theoretical physics from the University of Sydney in 1987, then held a postdoc at the University of Colorado at Boulder until 1990. He then returned to Australia, joining the permanent staff of the School of Physics at the University of Sydney in 1994, and obtaining a chair in 2000. He is currently an Australian Research Council Federation Fellow working on topics including sleep, brain dynamics, space physics, plasma theory, and wave dynamics.

"Pluto and the uber-nerds"

Fred Watson, Anglo-Australian Observatory at Coonabarabran

Wednesday 7 July 2010 at 7 pm

Conference Room 1, Darlington Centre, University of Sydney

When is a planet not a planet? When it's a dwarf-planet, perhaps? So what's the difference? In 2006, astronomy's governing body, the International Astronomical Union, wrestled with this very question at their General Assembly in Prague. Before we knew it, media all around the world had declared that Pluto had been "dumped" from its status as the ninth planet, hinting that it had been unfairly thrown out of the Solar System. And in 2008 things got worse, with Pluto joining the lowly ranks of a new class of objects with the unflattering name of Plutoids. In this entertaining and fully illustrated journey through Pluto's eventful history, Fred Watson debates whether pragmatism and good science should prevail over sentiment and tradition.

Fred Watson says he has spent so many years working in large telescope domes that he has started to look like one. He is Astronomer in Charge of the Anglo-Australian Observatory at Coonabarabran, where his main scientific interest is gathering information on very large numbers of stars and galaxies. He is also an adjunct professor at the Queensland University of Technology, the University of Southern Queensland, and James Cook University. Fred is the author of "Stargazer: The Life and Times of the Telescope", and is a regular broadcaster on ABC radio. His new book "Why is Uranus upside down?" is based on listener questions, and was published in October 2007 and won the 2008 Queensland Premier's Literary Prize for Science Writing. In 2003, Fred received the David Allen Prize for communicating astronomy to the public, and in 2006 was the winner of the Australian Government Eureka Prize for Promoting Understanding of Science. Fred has an asteroid named after him (5691 Fredwatson), but says that if it hits the Earth it won't be his fault ...

"Photonic circuits for the new information age: faster, smaller, smarter and greener"

Ben Eggleton, Professor of Physics, ARC Federation Fellow, Director of the Centre of Excellence for Ultrahigh-bandwidth Devices for Optical Systems (CUDOS) and Director of the Institute of Photonics and Optical Science (IPOS)

Wednesday 1 August 2012 at 6.30 pm

Union, University and Schools Club, 25 Bent Street, Sydney

Meeting report by Donald Hector

The ARC Centre for Excellence for Ultrahigh-Bandwidth Devices for Optical Systems (CUDOS) is a world-leader in research in photonics and the development of photonic devices. Its director, Professor Ben Eggleton, gave a wide-ranging talk about the Centre's work and photonics generally.

The use of light to communicate information is by no means a novel concept. Signals such as flags and lights for sending information have been used for many hundreds if not thousands of years. In the last couple of hundred years, various systems have been devised such as collimators and various lens systems. Three major breakthroughs of the last half-century or so were the invention of microelectronic devices, the invention of the laser and, importantly, the discovery by Charles Kao in 1966 that the physical properties of glass fibres were ideal for transmitting optical signals. Photonics, which combines these technologies, provides extraordinary capability for extremely high-speed transmission of data through optical fibre.

The reason that glass fibre is suitable is that there is a narrow part of the absorption spectrum in glass about 25 THz wide where attenuation of the signal is only about 0.2 dB per kilometre. Lasers can generate discrete packets of visible light light that can be transmitted down the fibre. Importantly, the photons do not interfere with one another and can be separated at the other end and the data encoded in the packets of light can be read. The relatively small signal loss can be managed by periodically installing amplifiers along the fibre-optic cable. There are now fibre-optic networks joining all major continents and these are the primary means for moving digitised data around the world.

A significant advantage of this fibre-optic technology has been its scalability. Developments in photonics and vastly increased the capacity of fibre-optic cables since the first ones were laid over 20 years ago. The National Broadband Network that Australia is currently installing is intended to deliver 1 Mb per second to well over 90% of households in Australia. There has been some speculation that this may become obsolete but this is unlikely as technological pathways to upgrade this to one terabit per second are already on the horizon.

One of the areas that CUDOS is working in is the application of nanotechnology and the development of materials with physical properties that do not occur in nature. These are giving rise to some novel applications such as "cloaking" (where photonics can be applied to make things appear invisible in certain parts of the spectrum). Other real possibilities of nanotechnologies are the development of a three-dimensional microchips that would allow major steps forward in processing speed.

Although in principle, photons do not interact with one another in a vacuum, in a medium such as glass, high-intensity laser excitation can cause a non-linear response of the glass medium and cause the photons to interact with one another. Conceptually, this may make possible the development of ultrahigh speed devices, switching as quickly as 1 trillionth of a second. This would make them up to 1000 times faster than current optical devices.

The Centre for Excellence for Ultrahigh-Bandwidth Devices for Optical Systems is recognised as one of the top few photonics research centres in the world. It is a collaboration of eight of Australia's top universities and number of industry participants. Expectations are high that it will make a major contribution in the emerging field of photonics.

"Climate change, regional drought and forest mortality: are we seeing a new global phenomenon?"

Professor Derek Eamus, University of Technology, Sydney

Wednesday 5 September 2012 at 6.30 pm

Union, University and Schools Club, 25 Bent Street, Sydney

Meeting report by Donald Hector

Around the world, forests seem to be under stress. At the 1203rd OGM, Professor Derek Eamus, a plant physiologist at University of Technology Sydney, gave a fascinating talk on what is causing the major problems in the world's forests and the implications if there is a substantial increase in global temperatures. In every continent there are numerous examples of forest die-back in recent years. Understanding the background of this is critical given the importance of forests in the global ecosystem. Forests are large repositories of carbon, have a large influence on the way in which water moves through the environment, are important for biodiversity, have a major impact on the absorption of energy from the sun and have high amenity value.

There are two theories to explain die-back of forest during drought conditions. The first of these is carbon starvation. This is an important factor in forest health particularly with isohydric trees species (isohydric trees are those that regulate water flow in order to maintain canopy humidity within a relatively narrow range. They do this through opening and closing leaf stomata in response to changes in humidity). When the stomata close, no carbon dioxide can enter the leaf. One response of isohydric trees to drought conditions is to close the stomata in order to preserve water. Thus, during a protracted drought, the tree closes the stomata close and cannot absorb carbon dioxide and will gradually starve to death.

The second theory is that forests die due to hydraulic failure. This is a particular problem with anisohydric species (unlike isohydric trees these do not respond to drought by closing stomata, so the tree continues to absorb carbon dioxide). The problem is that if the ground water availability drops too low, there is insufficient water potential causing embolism in the xylem (the fine tubes that conduct water from the root system to the leaves) and this interrupts water flow to the leaf system.

Catastrophic failure of forests during drought conditions seems to be related to one or other of these effects. Observation suggests that droughts of long duration cause hydraulic failure, whereas drought soft high-intensity cause carbon failure followed by hydraulic failure. These observations may have substantial implications for Australia's forests. Australia has highly variable rainfall and the annual evaporation in many areas is higher than the annual rainfall. River discharges are also much lower than other than Europe, Asia, Africa or the Americas. The accepted wisdom is that temperature is the main determinant of forest mortality due to drought and usually occurs a couple of years after the drought finishes.

Professor Eamus and his co-worker, Nicolas Boulain, have developed a conceptual model that relates duration of drought conditions and their intensity to the reasons for forest failure. They question the conventional wisdom that temperature is the most influential determinant. They have developed a mechanistic model of forest behaviour that disaggregates a number of the parameters that of been incorporated into the highly sophisticated soil-plant-atmosphere (SPA) models. One important parameter is the vapour pressure deficit (VPD), a measure of canopy humidity. Modelling 15 scenarios indicated that temperature stress is not a major determinant of forest mortality; what is important is VPD. It is the combination of an unusually high temperatures and very dry conditions thereby reducing VPD that does the damage. They conclude that VPD is an important parameter that needs to be included in climate models.

Professor Derek Eamus is a plant physiologist and ecophysiologist who leads the Terrestrial Ecohydrology Research Group within the Plant Functional Biology and Climate Change Cluster at the University of Technology, Sydney.

"Outsmarting superbugs?"

Professor Liz Harry, Professor of Biology, School of Medical and Molecular Sciences, University of Technology Sydney

Wednesday 3 October 2012 at 6.30 pm

Union, University and Schools Club, 25 Bent Street, Sydney

Meeting report by James Kehoe and Jude Allen

Bacterial infections have become increasingly resistant to current antibiotics. The ability of bacteria to adapt rapidly to their environments, including the presence of antibiotics, is outstripping our ability to discover and refine novel agents. Bacterial infections have become increasingly resistant to current antibiotics. The ability of bacteria to adapt rapidly to their environments, including the presence of antibiotics, is outstripping our ability to discover and refine novel agents.

At the 1204th OGM, Professor Liz Harry of the University of Technology Sydney delivered a lively and informative talk concerning the role of bacteria in our lives, the mechanisms by which they adapt, and tests of alternative methods for defeating them without producing resistant strains.

Prof. Harry first provided an overview of bacteria, particularly their prevalence in nearly every possible habitat on Earth. Nearly every surface – large or small – is covered by bacteria, as either free-living individual cells or in multicellular aggregates embedded in a self-produced extracellular polymeric substance, known more colloquially as "slime". These biofilms can be particularly resistant to antibiotics.

In both these forms, bacteria constitute a total biomass that exceeds that of all plants and animals, even though an individual bacterium is typically a few micrometres length. Within human bodies bacteria, living most notably on our skin, in our digestive tracts, and in our respiratory tracts, outnumber human cells, possibly by a factor of ten. Prof. Harry quipped that we are more bacterium than human. Commercial advertisements often paint bacteria as agents of disease that must be eradicated, preferably by the advertiser's product. In fact, the bulk of bacteria in and around humans are harmless or long-ago neutralised by our immune system. An attempt eradicate all bacteria from humans, apart from being futile, is likely to provide an opening for invasion by dangerous species. According to Prof Harry, ordinary cleanliness, especially hand-washing, is sufficient to wash away invaders while retaining our familiar and possibly protective bacteria. The ability of bacteria to adapt rapidly to new antibiotics is enhanced by the multiple ways by which they can introduce genetic variation. On the one hand, the most familiar form of bacterial reproduction is asexual cell division. Through this mechanism, bacteria can proliferate at astonishing rates, but evolution through cell division would have to rely entirely on random mutation to produce variation, which would leave bacteria largely open to attack by antibiotics.

On the other hand, bacteria readily recombine genetic material by a variety of methods, which include:

• Conjugation, sometimes called "bacterial sex," in which DNA is passed from one bacterium to another by a tube called a pilus.
• Transformation, in which bacteria incorporate DNA floating in their environment, often originating from dead bacterial cells.
• Transduction, in which bacteria exchange DNA via viral infection and reproduction.

Notwithstanding attempts to identify new antibiotic agents, bacteria seem to have the upper hand through rapid adaptation to any single agent. The best strategy appears to be a combined approach, in which a diversity of agents simultaneously attack different pathways and structures in bacteria, thus flooding their adaptive capability. Rather than trying to synthesize a joint agent, one answer may already be available in the form of honey, which has long been a traditional remedy for a variety of conditions and injuries. Prof. Harry showed photographs of a case in which honey-impregnated dressings helped to heal infected skin ulcerations that had resisted other antibiotic treatments.

Prof. Harry and her colleagues have been experimentally testing the ability of honey to serve as a topical antibiotic. Honey appears to have a general antibiotic property that allows it to be safely stored by bees and on our kitchen shelves for extended periods. Some honeys seem to possess strong antibacterial properties, including a variety from New Zealand. The unique factor appears to arise from the nectar of certain plants; in Prof. Harry's case, it is the Manuka plant. Prof. Harry suspects that the antibacterial properties of honey rely on the joint effect of a host of factors contained in the honey.

Prof. Harry concluded that, thanks to the effectiveness of antibiotics, modern society has become a bit blasé about basic cleanliness and too reliant on expecting a quick fix. At the same time, research on antibacterial agents of all varieties has languished, because effective antibiotics, which are commonly used for brief periods of time for acute conditions, are relatively unprofitable compared to drugs for managing chronic conditions, for example, hypertension.

"Science for gentlemen - the Royal Society of New South Wales in the nineteenth century"

Peter J. Tyler, Historian for the Royal Society of New South Wales

Wednesday 2 June 2010 at 7 pm

Conference Room 1, Darlington Centre, University of Sydney

Scientific activity in New South Wales began when James Cook and Joseph Banks voyaged along the eastern coast in 1770. This was the Age of Reason, when educated men challenged traditional knowledge handed down from antiquity and the Bible. Curiosity about natural history had become a fashionable pursuit when the penal settlement at Sydney Cove was established in 1788. Settlers and colonial officials collected and classified the animal, vegetable and mineral constituents of their unfamiliar environment. Even some of the convicts found a profitable sideline collecting shells, birds, plants, and aboriginal artefacts for sale to visiting ships' captains, who in turn sold them for high prices to wealthy collectors in Britain and the Continent.

In June 1821, towards the end of Lachlan Macquarie's term as Governor, seven men formed the grandly named Philosophical Society of Australasia "with a view to inquiring into the various branches of physical science of this vast continent and its adjacent regions." Although it only survived for a little over a year, this was a predecessor of the present Royal Society of New South Wales.

During the nineteenth century the Royal Society and its three antecedents functioned as an exclusive club for men "of honourable reputations" interested in the natural sciences. Almost without exception the members were pastoralists, merchants, or professionals such as clergymen, lawyers or medical practitioners. They classed themselves as gentlemen, because they were not engaged in physical labour. Only a handful were what we would now call scientists, because separate disciplines were only beginning to emerge, and career opportunities were few.

This does not mean that science was merely a hobby, or a part-time diversion. Members read the latest overseas journals diligently, they collected specimens and published papers - often descriptive rather than analytical - and they engaged in vigorous discourse on many of the contentious issues of the period, including Darwin's theories of species evolution at a time when such views were deeply unpopular in Australia. A few conducted original research in fields such as astronomy, geology and aeronautics.

Members of the Royal Society were part of the colonial conservative establishment. Women were excluded, while rigorous admission procedures ensured that "working men" did not become members. Nevertheless, the Royal Society recognised the need to educate or inform the broader public about the achievements of science, and organised regular gatherings for that purpose. It would be easy to characterise the members as typical class-conscious paternalists of the Victorian era, but there were always a few dissenters who did not fit that model.

In the twentieth century more inclusive attitudes emerged gradually, reflecting the changes in the wider community. Today it is difficult to discern any remnants of the earlier caste system. A question we might ponder is - has the influence and public profile of the Royal Society diminished at the same time?

Peter J. Tyler is the Historian for the Royal Society of New South Wales. In 2008-2009 he was the inaugural Merewether Research Scholar at the Mitchell Library. Peter has a BA degree in geography and a Master's degree in history from the University of New England. His PhD thesis from that institution examined the role of the Board of Health in public health administration in NSW from 1881-1973. He also holds a Graduate Diploma in Adult Education from UTS. Previously he worked in management positions in the public, private, and not-for-profit sectors, including fifteen years as Secretary and chief executive of the Workers' Educational Association in Sydney. His published books range over such diverse fields as health care, the building industry, and the public service. Peter Tyler has been President of the NSW Branch of the Australian and New Zealand Society of the History of Medicine, and of the Professional Historians Association (NSW).

by Donald Hector

The middle of the 19th century was a time of great change in NSW. Responsible government was introduced in 1856 and full manhood suffrage followed two years later. Queensland separated from NSW a year after that. And just 10 years after the introduction of responsible government, Queen Victoria granted Royal Assent to the title of The Royal Society of New South Wales. However, as Dr Peter Tyler, the Society's Historian, explained in his lecture at the 1181st ordinary general meeting on 2 June 2010, The Royal Society of NSW traces its origins back to 1821 when The Philosophical Society of Australasia was formed. There were several early attempts to form such societies with mixed success but this should not understate the commitment of a group of progressives who wanted to see the natural history, agriculture, and culture of the nascent colony flourish.

The Philosophical Society of Australasia was established under patronage of the Governor, Sir Thomas Brisbane and he also became its first President. The founding members included Major Goulburn (the Colonial Secretary) and Edward Wollstonecraft a wealthy merchant and landowner at North Sydney. The purpose was to study the physical sciences and the mineralogy of NSW (which then, of course, included what is now Queensland and Victoria). The early Society only lasted a year or so but there were other attempts to stimulate more intellectual activities in the colony in the first part of the 19th century. The first subscription library was started by Wollstonecraft in 1826 and between 1820 and 1850 other societies began, such as the Agricultural Society (which lapsed for some years and then was re-established in the 1850s), The Australian Society for the Encouragement of Arts, Science, Commerce, and Agriculture (more commonly referred to as the Australian Philosophical Society) but, like the early Philosophical Society, these early groups generally did not thrive.

But by the 1860s, with Sydney having been formally declared a city (in 1842), NSW having been granted responsible government, and the buoyant economic growth of the period created an environment where interest in science, art, and literature blossomed. The University of Sydney was founded in 1854 and the time was right for a successful society to be established.

Just six years after the granting of Queen Victoria's Royal Assent there were 122 members of the Society across a range of occupations - pastoralists, businessman, scientists, artists, lawyers, and the clergy - and by the 1890s there were nearly 500 members. In the latter half of the 19th century a number of eminent scientists (Prof John Smith (physics and medicine), Prof Archibald Liversidge (geology and chemistry), Sir Thomas Anderson Stuart (physiology) were but a few). The Society's transactions were published in a prestigious peer-reviewed journal (which continues today) and attracted publications from such eminent scientists and engineers as Lawrence Hargrave.

The first 80 years of the Society were colourful, strongly influenced by the personalities of the time when NSW was finding its feet as a society. Dr Tyler's work was made possible through his appointment as the inaugural Merewether Scholar of the State Library of NSW.

"The unexpected nuclear renaissance: nuclear techniques benefiting mankind"

Dr Adi Paterson, CEO, Australian Nuclear Science and Technology Organisation (ANSTO)

Wednesday 7 November 2012 at 6.30 pm

Union, University and Schools Club, 25 Bent Street, Sydney

Meeting report by Donald Hector

The Society was privileged to have Dr Paterson, chief executive officer of ANSTO, address our meeting on Wednesday 7 November in Sydney.

There has been great excitement in recent months with reports that two experiments at the CERN Large Hadron Collider (LHC) had detected phenomena indicating the existence of the Higgs boson. The CERN LHC is the current pinnacle of cyclotron accelerator technology that was first developed in the 1930s. Not only is this technology at the forefront of experimental physics but the spin-offs, such as PET imaging and hadron therapy have been major developments in medical diagnosis and treatment. There are now over 860 cyclotrons worldwide, with 11 of these in Australia.

The cyclotron is one of two great traditions in nuclear physics – the other is the research nuclear reactor. Generally, nuclear isotopes that are useful for diagnosis can be generated in cyclotrons while the radioactive isotopes for therapy are more often produced in nuclear reactors, such as the Opal Research Reactor at Lucas Heights. An example of the use of isotopes in the diagnosis of disease is early detection of Alzheimer's dementia. Alzheimer's is difficult to diagnose in its early stages and, often, can only be positively identified post-mortem. However, positron emission tomography (PET) scanning technology can detect markers that appear to be associated with abnormal amyloid-beta production, a phenomenon that appears to be associated with Alzheimer's disease. PET diagnostic techniques utilise a radiopharmaceutical compound called florbetapir-fluorine-18 that contains the radionuclide fluorine-18. Fluorine-18 is a radioisotope of fluorine that emits positrons as it decays and these can be detected in a PET scanner. It has a short half-life (about 110 minutes) and has essentially disappeared from the body in about 12 hours. Similar techniques are also being used in diagnosing the effects haemorrhagic stroke and progress of insulin cells in diabetes patients.

The Opal Research Reactor at Lucas Heights is an important source of short half-life isotopes used for a variety of medical and non-medical purposes. These can be as diverse as researching the structure and physics of new generation batteries, sensing explosives using photo luminescent films, understanding the morphology and structure of organic light-emitting diodes (an important new technology), studying the structure of cell membranes, stress evaluation in steel (for example, analysing the heads of railway track in order to predict failure). Medical treatment is a critical role for the Opal Reactor, particularly for supplying short-lived isotopes for radiation treatment of cancer patients.

The other important facility in Australian nuclear physics is the Australian Synchrotron that is being used for medical imaging and therapy and a range of other applications. One of the critical applications for the synchrotron is protein crystallography. This technology emerged from Nobel Prize-winning work in determining the structure of various proteins, that could not be done otherwise.

The important message that we were left with is that the Australian Synchrotron and the Opal Reactor are complimentary technologies. Together they provide critically important resources in a range of Australian industries from medical diagnosis and treatment to latest technologies across a variety of science and engineering applications. Furthermore, they give us a place at the table internationally in leading-frontier "big science".

"The weird world of nanoscale gold"

Mike Cortie, Director of the Institute for Nanoscale Technology, University of Technology, Sydney

Wednesday 5 May 2010 at 7 pm

Conference Room 1, Darlington Centre, University of Sydney

Mike Cortie is the Director of the Institute for Nanoscale Technology at the University of Technology, Sydney (UTS), in Australia. He was born and educated in South Africa. He has a BSc(Eng) degree in Physical Metallurgy, a Masters degree earned from research on the corrosion of zirconium and a PhD degree, which was focused on metal fatigue and awarded in 1987. After a stint at South Africa's Atomic Energy Corporation and at Pylon Engineering, a gear-cutting works, Mike joined Mintek, a minerals and metals research organisation. Mike headed the Physical Metallurgy Division of Mintek between 1997 and 2002. The Division consults widely to South African and international industry and now generates the major portion of its funds from foreign contract research. He relocated to Australia and joined UTS in July 2

Mike's current research interest is nanotechnology, and in particular the applications of precious metals in nanotechnology. Previous research activities included research on ferritic and nickel-substituted stainless steels, on intermetallic compounds with the C1 (CF12) and B2/L21 crystal structures, on X-ray diffraction and crystallographic texture of bcc and fcc alloys, on cellular automata and the simulation of metal solidification, cracking and solid state transformations, on explosive interactions between molten metal and water, on displacive transformations in Pt-containing alloys and compounds, on the phase relationships in the Al-Au-Cu ternary system, and on the crystal structures of the martensite phase formed by displacive phase transformation in the b Au-Al-Cu shape memory alloy. He has also been active outside the materials arena, and has made contributions to the mathematical modelling and graphics rendering of mollusc shells, and the science education of children.

Presentations by Royal Society of NSW scholarship winners 2013

The 2012 Scholarship winners presented at the first meeting of 2013 held at the Union University and Schools Club on Wednesday 6 February.

Helen Smith (left) is completing her PhD at Sydney University as part of a Sydney-based conservation programme to reintroduce the native bush rat into the Sydney Harbour National Park. If successful, this promises to be an effective way of displacing introduced rats that have had significant impact on local wildlife. Initial indications suggest that, once established, native rats successfully compete with introduced rats.

Anwen Krause-Heuer (right) is in the midst of a PhD at the University of Western Sydney and is working on the development of new cancer drugs based on cis-platin. The aim of the workers to develop platinum-based anti-cancer complexes that have lower toxicity than established treatments.

Jendi Kepple is undertaking a PhD at the University of NSW and is investigating the design of various alloys and composite materials to improve the design of launch vehicles used in the European space programme. (Unfortunately Jendi was not able to attend evening as she was at a conference overseas. She was well represented by one of her colleagues.)

"The evolution of galaxies" - Dr Ray Norris

Ray Norris, a senior astrophysicist with the CSIRO spoke at the 1208th OGM of the Society on one of the Australian Square Kilometre Array Pathfinder (ASKAP) projects, Project EMU – an acronym for evolutionary map of the universe.

The ASKAP project is the first phase of the $2 billion Square Kilometre Array project shared between South Africa and Australia. The cost of this phase is $170 million and is being built in Western Australia.

It consists of 36 12-m radio antennas that have extraordinarily high resolution, using devices called phased-array feeds. Project EMU is one of two high-priority projects that are currently underway. Emu will conduct a deep survey of a patch of dark sky, making deep images at several different wavelengths to create a census of all galaxies within the patch being examined.

The aim is to identify the different evolutionary tracks of galaxies and, hopefully, to identify some important but rare transitional stages. The survey is expected to be able to look back in time to the formation of the first stars around 400 million years after the big bang that took place 13.7 billion years ago. Radio telescopes are ideal for this type of survey because they are unaffected by dust. When combined with infrared and optical data, they can give a very powerful image of their field of view.

Dr Norris outlined many of the phenomena that EMU is investigating. The science goals of the EMU project are to better understand the evolution of massive black holes, to explore the large-scale structure and cosmological parameters of the universe (for example, test theories about dark energy) and to explore diffuse low-surface-brightness radio objects. The project will also add substantially to a large database of surveys that can be mined as computing capacity continues to increase.

Inaugural Fellows Lecture - Professor Michael Archer AM

"An evolutionary history of Australia"

The Society was proud to have Professor Michael Archer AM present the inaugural Fellows Lecture on Wednesday, 3 April 2013. Professor Archer was one of the first Fellows appointed by the Society, recognising his outstanding work as a palaeontologist, particularly in relation to the Riversleigh fossil find in Queensland, one of the richest fossil deposits in the world.

Until about 50 years ago, only about 70 fossil mammals had been found in the whole Australian continent, compared to about 50,000 in North America. The geology of the Riversleigh area, in northern Queensland, is unusual. There are large expanses of very old (1.6 billion years) Precambrian rock and more recent Cambrian deposits (500 million years old) that contain rather unremarkable fossils of the era. But there are pockets of more recent geological deposits, 10-25 million years old, that have been found to contain extraordinarily well-preserved fossils. There are about 40 sq. km of these deposits. A wide range of unusual animals have been found: five kinds of thylacine, giant, toothed platypus, flesh-eating kangaroos and ancient birds. Some of the birds are the biggest ever discovered and would have weighed up to 400 kg. Also, huge fossilised snakes, importantly, a diverse range of ancient bats and a great variety of trees and plants have been discovered.

How did this extraordinary preservation take place? Professor Archer explained that there were two phenomena that together resulted in this remarkable deposit. Water that percolated up from subterranean deposits were saturated in calcium carbonate and this quickly precipitated around any dead animals that fell into the water. This was responsible for preserving skeletons intact and is easily removed using weak acid such as acetic acid that quickly dissolve the calcium carbonate, exposing a well-preserved fossilised skeleton. But in addition, another phenomenon called 'bacterially-mediated phosphatisation', means phosphates from bat droppings have preserved soft tissue, resulting in remarkably complete fossils being found in many areas. In a process known as 'tufagenic barrage', calcium carbonate deposits formed dams that allowed fossilisation to take place. These dams were ultimately breached but the fossils were preserved. At the time, Riversleigh area was covered with rainforest but this has gradually receded to coastal zones.

The Riversleigh deposits cover five phases from 25 million years ago to 1.5 million years ago and is the richest sequence in Australia. (There is only one other similar deposit in the world – this is in France.) The Riversleigh find has completely changed perceptions about Australia's past. It is now clear that there is a diversity in the fossil record suggesting an environment that was as rich at the time as Borneo and the Amazon regions are today. About 15 million years ago Australia started to dry out, yet it was not until about 3 million years ago that extensive grasslands formed.

Professor Archer pointed out that the fossil record gives us a very rich understanding of the way in which current species have evolved from which we can deduce how habitat change can be managed and to protect species that might be at risk of extinction as climate change takes place. We can also gain insight into which species are at threat by understanding the extent to which their populations have increased or declined over long periods of time.