The crumbling wall
From Griffith REVIEW Edition 31: Ways of Seeing
© Copyright Griffith University & the author.
Written by Ian Lowe
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Ian Lowe's biography and other articles by this writer
I GREW up in an era when science had an aura of certainty and solidity: it was ‘the true exemplar of authentic knowledge’, as the eminent sociologist Robert K Merton put it. History inevitably contains a subjective element, and there are different and legitimate views about the significance of a work of literature, but science was different. At school we learned which chlorides are insoluble and which metals are attacked by hydrochloric acid: no room for subjectivity or different interpretations there. We learned the laws of motion, as set down by Newton hundreds of years ago: not theories but laws that can’t be broken. The science was incontestable, so your answer in the school test was either right or wrong. At university, all the physics and chemistry I learned as an undergraduate was solid, unquestioned knowledge.
Science spoke with a particular authority. It has been argued that other disciplines were affected by this perception; some observers think ‘physics envy’ led economics down the path of mathematical modelling and arcane theories that, applied to financial products, wrought havoc in the real world. That is another story.
Applying science had produced technical marvels that significantly influenced World War II, like radar, culminating in the fearsome weapons that obliterated two Japanese cities and brought the war to an end. Applying science to our domestic life gave us clean drinking water, protection from diseases, cleaner and faster cooking, better communications and a dramatically improved material lifestyle.
Governments cheerfully funded science, confident that the goose would continue to lay golden eggs. The highest-achieving school leavers were more likely to study science at university than arts, law or medicine, let alone courses in economics or commerce. The CSIRO, originally set up to improve our primary industries, extended its work into manufacturing and information processing. Most politicians worshipped the new deity and appeased it with regular offerings, though some were more cautious; Winston Churchill famously said that scientists should be ‘on tap, not on top’, working as directed.
To some extent, the perception that science produces permanent knowledge still applies in the laboratory. I recall my doctoral supervisor saying in admiration of a distinguished colleague, ‘When he measures something it stays measured!’ That fabled scientist spoke disparagingly of ‘those romanticists’, a research group he believed to espouse theories that went beyond the solid evidence from experiments. Predictability is not just a perception: ask a scientist to measure something under controlled conditions, the melting point of a specified alloy or the rate of reaction between two chemicals, and you can expect a precise answer. What’s more, you can expect the same precise answer from any competent professional. In the artificial world of the laboratory, where all the relevant variables can be controlled, science gives clear and verifiable answers, with little room for subjective interpretation.
THE FIRST CRACK in the wall was the analysis by the physicist and historian Thomas Kuhn of what he called scientific revolutions. He used specific examples: the old earth-centred view of the universe and physics before the development of quantum theory. In each case the old science was working diligently within what he termed the dominant paradigm, a phrase that is now part of the political lexicon. He showed that ‘normal science’ accepted the existing theory and worked within it, collecting data and solving small puzzles. But the accumulating evidence led to increasing awareness that the prevailing theory was inadequate.
Even then, Kuhn argued, the old theory was not rejected until a new and better theory was developed to explain the observations. In each case, adherents of the old theory were understandably reluctant to admit that their life’s work had been in vain. They often tried to find a contorted logic that fitted the new evidence into the old theory. Kuhn concluded the new theory would triumph only when proponents of the old one retired or ceased to have influence, leaving the field to the Young Turks who saw the improved explanatory power of the different approach: a scientific revolution.
I saw two examples of Kuhn’s theory in action in the 1960s: the continents and the origin of the universe. The theory of continental drift had been around since the nineteenth century and made instinctive sense, since the east coast of South America is strikingly similar to the west coast of Africa and it looks to the amateur eye as if they could once have fitted together. But scientists could not imagine continents moving around on the face of the earth, and the theory was dismissed as populist nonsense. It all changed when one critical measurement found the sea floor spreading around the Mid-Atlantic Ridge, showing that the continents were actually moving apart. Within about five years, the old superstition of continental drift had become the new science of plate tectonics. This in turn made sense of a wide range of previously puzzling observations, from the continuing growth of the Himalayas (the result of the Indian Plate colliding with the Asian Plate) to the biological parallels in Africa, South America and Australia resulting from the earlier existence of the super-continent now called Gondwanaland.
In the case of the origin of the universe, there were two competing theories at the time, known as the steady-state model and what was condescendingly called the big bang, the idea that the universe was still expanding from a cataclysmic event about fourteen billion years ago. There was no solid evidence, so the two theories were both intellectually defensible.
It was my first experience of scientific controversy when the University of Sydney brought leading proponents of the two competing theories to a physics summer school. After George Gamow expounded the big bang theory, Thomas Gold stood up and told the audience why he could not accept that explanation. The following day the roles were reversed, with Gamow explaining why he could not accept Gold’s equally learned exposition of the steady-state model.
The debate raged for another decade or so. The evidence steadily accumulated in favour of the big bang, but some supporters of the steady-state model found convoluted ways to reconcile the new observations with their preferred theory. Eventually one crucial measurement effectively resolved the issue. Calculations based on the big bang theory showed that there would be residual radiation now, at the very low temperature of 4.2 degrees Kelvin (or nearly -270 degrees Celsius), if their model was correct. When that radiation was detected, the argument was resolved.
In more recent times, a parallel was the debate in the scientific community about global climate change. The underlying basic science is well understood. The British physicist John Tyndall showed in the 1850s that carbon dioxide absorbs infrared radiation. Svante Arrhenius, the Swedish physicist and chemist, called it a ‘greenhouse’ gas in 1892, arguing that it had the same effect as the glass in a greenhouse. Glass is transparent to visible light, but absorbs infrared radiation. So when the sun shines on a greenhouse (or a car parked in the sun) the sunlight warms the interior. The heat would normally be radiated away, but the glass prevents this happening and the temperature rises, desirably in a greenhouse but uncomfortably in a car.
Arrhenius pointed out that the same ‘greenhouse effect’ occurs in the earth’s atmosphere as sunlight passes through and warms the surface, but the radiation of heat into space is slowed by carbon dioxide, water vapour and other trace gases in the atmosphere. Two examples illustrate this effect. A clear night in winter is much colder than a cloudy night. The belt of water vapour on a cloudy night slows the radiation of heat away from the earth into the cold night sky. The large-scale example is the climate on the moon, which is the same average distance from the sun as the earth. The moon has no atmosphere, so the temperature plummets when the surface is not receiving sunlight. The difference between day and night is about 250 degrees Celsius, compared with ten to twenty on earth, and the average temperature is thirty-three degrees lower. There is no doubt that the ‘greenhouse effect’ exists and makes conditions much better for life on earth. Arrhenius calculated in 1892 that doubling the amount of carbon dioxide in the air, say by burning huge amounts of coal, would increase the average global temperature by four to five degrees.
In the 1950s scientists began to measure the increasing concentration of carbon dioxide in the atmosphere. By the 1970s some were expressing concern that this could change the global climate. In 1985 a critical international conference reviewed the evidence and said that the release of greenhouse gases seemed to be changing the climate.
Both greenhouse gas concentrations and average global temperatures were increasing, but cautious scientists warned that the evidence did not prove a causal link. The Intergovernmental Panel on Climate Change was set up to examine the evidence and recommend responses. Its four reports reflect steadily growing confidence that the recent changes in global climate are a direct consequence of human release of greenhouse gases. This has persuaded most politicians that concerted action is needed.
A small number of reputable climate scientists, a group you could count on the fingers of one hand, still say they are not convinced of the causal link. They have been supplemented in the public debate by a larger group of people, some scientists outside the specialisation but most with no scientific credentials at all, to argue against action. The attention given by the media to those in denial has created a public impression that the science is uncertain, whereas the science has been settled within the relevant community for at least a decade.