Alan Saunders: Today, a question: what is the ideology that propels scientists to go to so much trouble?

Think, for example, of the hazards involved in a voyage from Europe to our part of the world in the 18th century. Why would you go to all that effort just to observe the Transit of Venus? And why would the people who sent you want to shell out all that money for the trip?

So, today, on The Philosopher's Zone, we're celebrating both their courage and National Science Week by exploring the philosophy of northern astronomy in the Southern Hemisphere.

I'm Alan Saunders and I'm delighted to welcome Simon Schaffer, Professor of the History of Science at the University of Cambridge.

Simon Schaffer: I'm very pleased to be here.

Alan Saunders: To begin with, why is the Pacific region important in the history of essentially Northern Hemisphere astronomy?

Simon Schaffer: This is a very good question. The experience of travel in general, shipboard travel, and especially shipboard travel in what for Europeans were largely unknown waters, tested out in really fundamental and challenging ways, a whole series of techniques and ideas that European astronomers had worked out in Europe and the North Atlantic, almost to, and in some cases absolutely to, destruction; whether it was the astronomy of position (in other words astronomy that people could use on board ship or on land) to find out where they were, or wider senses of astronomy: cosmologies. By which I mean encounters with other peoples who do not share the Europeans' scientific sense of the organisation of the universe. That was also a very important aspect of the encounter with the Pacific.

Alan Saunders: And there were various things that you might try to look at in southern skies, most notably the transit of Venus. You might perhaps explain to us, firstly what the transit of Venus is, and secondly, why it was so important.

Simon Schaffer: Well it's fascinating, because it plays such an important role in the motives for the British entry into the Pacific in the 1760s and '70s. It had been worked out since the 1600s effectively, that if one could observe the rate at which Venus moves across the face of the sun, when the Earth and Venus and the Sun are appropriately aligned, then you could work out how far the Earth from the Sun is, which is the basic measuring-rod of all astronomy.

What was required was to observe the transit at different places on earth, and measure, as precisely as you could, the moment when this tiny planetary disc crossed the edge of the sun, (that's called ingress), and the moment when it left the face of the sun (that's called egress). And since that time, the time between ingress and egress, will differ according to where you are on earth, if you know the distance between two observing places on earth, and you know the difference in the times of the transit as seen from those two places, you can work out by geometry how far away the sun is from earth.

Alan Saunders: Well already it's clear that an important philosophy or if you like, ideology, has to be at play here, because if you're going to be in all these places at once, it's helpful to have an imperial sub-structure to enable you to do that.

Simon Schaffer: That's absolutely right. The first international Venus transit project is in 1761, and then again in 1769. Transits of Venus happen in pairs more or less, each century, and the 18th century transit projects reveal unambiguously the importance of new, relatively reliable, very long distance international political, commercial trade networks, without which, distributing reliable observers and perhaps even more importantly, reliable hardware over the surface of the earth, would have been completely impossible. And they also reveal something whose importance I think we sometimes forget, which is the importance of co-ordination; of the existence of what we might call centres of calculation in the metropolis, where all this data can be juxtaposed, analysed, and compared.

Alan Saunders: Let's look at the science itself, the science of astronomy. You've said that astronomy is the most confined of sciences, and you quoted the 19th century philosopher and historian of science, William Whewell, the man who actually gave us the word 'scientist', as describing astronomy as his pattern science. What did he mean by that?

Simon Schaffer: Yes, I think it's a really eloquent expression. Whewell, Cambridge philosopher, polymath, omniscience it was said was his foible, was writing one of the first really thorough histories and philosophies of the sciences, and it was very important for Whewell to imagine what an ideal science would look like, since he had held that all other sciences would, through the course of human history, converge gradually to the status of that science. And for Whewell, like many of his contemporaries in the first half of the 1800s, astronomy was obviously the pattern science, for at least these reasons. First of all, it had been cast into what seemed to them to be deductive form, with a very few relatively simple premises about matter, motion, force, action at a distance, it seems to be possible to deduce all the phenomena of heavens and earth. And that was an extraordinarily powerful theme in European attitudes to the sciences, that they should in the end, be deductive, certain, absolute.

But along with that, what impressed Whewell and his contemporaries, was that astronomy was on the other hand, completely based on precision observation. It wasn't an abstract science, it gripped what was really happening in the world, it absolutely relied on the observation of phenomena. So the combination of what we might call the observatory and the calculating room, seemed to Whewell and his contemporaries really magnificent, and it was for that reason that astronomy became their pattern.

Alan Saunders: In the early years of the last century, not quite 100 years after Whewell, the English philosopher, Alfred North Whitehead, rejected the idea that there was a bifurcation between what can be seen, which of course is vital to astronomy, as you've just said, what can be seen and what there is in the world. Now this seems obviously relevant to astronomy, given that astronomy was, as again you've just said, was really about what could be seen.

Simon Schaffer: Yes, I think Whitehead's intervention is absolutely fascinating. Whitehead had established his reputation as a collaborator with Bertrand Russell in writing an attempt, which didn't quite work but absorbed their energies for many years, to deduce the whole of mathematics from logical first principles.

During the First World War, Whitehead I think fascinatingly, began to be more and more sceptical of the basic philosophy on which men like Whewell, his great predecessor, had based their epistemology, based their theory of knowledge. Whitehead pointed out that one is constantly told especially as he put it by public scientists, that there are two kinds of qualities in the world: primary qualities, which according to the scientists and philosophers, are what there really is in the world: matter, motion, place, dimension. And then everything else that we seem to see in the world, so it was held, is an illusion, is a result of the doings of those primary qualities. And Whitehead called that, as you say, the 'grand bifurcation', and he attributed it to the 17th and 18th century.

He made the chief villains John Locke and Isaac Newton, and he rejected that grand bifurcation. He could not persuade himself that there's a fundamental difference between roughly what there really is in the world, and how the world seems. Why should we think that? That had, or would have had, enormously important consequences for the way one thought about the sciences.

For example, it would have restored to our conversations about the sciences, a whole series of doings and performances and practices that we normally don't take seriously at all. What we might call the affective, the sensuous aspects of sciences; the fact that in order to make reliable knowledge, we require things to have colour and texture and feel and smell, and that it's on the basis of really quite sophisticated judgments like that, that not just individuals but communities of enquiries construct the knowledge that they manage to achieve.

Alan Saunders: Astronomy in its early days had an obvious relationship to, well to the phenomenal, but also indeed to the sensual, inasmuch as before the age of photography, you had draw pictures of astronomical phenomena, and the result is that it has a somewhat uneasy relationship with art, doesn't it?

Simon Schaffer: Yes it's an entangled relationship which hasn't always been either happy or successful, and yet it's indispensible. One of the founding acts of anything like modern astronomy, after all, is the use by Galileo in March of 1610 in his stellar messenger of the new-found astronomical telescope, and Galileo's drawings of the position of the moons round Jupiter are revolutionary images. What's really interesting however is that in his later work, Galileo begins systematically to abandon using images and to move away from art, because at that period, it was widely held that the work of the artist, of the image-maker, devalued the status of the observer of the heavens.

By the period of the transits of Venus, the whole relationship between observing these exquisitely refined phenomena, the transit of a tiny dot over the slightly dull surface of the sun, required artistic ability, clearly, and artistic judgment, of a very, very high order. A very good example of this is what happens to James Cook and Charles Green on Tahiti in June of 1769 when they're making their observations of the Venus transit from that island, and they are hoping that there's a very clear moment when the black dot of Venus moves into the face of the sun. What they see, however, is what's come to be called the 'black drop effect', in which it looks as though Venus is bleeding across the surface, making it extraordinarily difficult to tell when the moment of ingress is.

They drew images of what they saw and when these images are brought back to London there's enormous controversy that lasts well into the 1900s about whether this is a real phenomenon, whether it's reproducible. Is it rather a phenomenon that comes from their own eyes than from nature itself? These are some of the many questions that the artfulness of the astronomical image-making raises I think in a very acute form. And finally, it's not obvious that the introduction of photography resolves all these problems; it does not.

Alan Saunders: Because photographs need to be interpreted.

Simon Schaffer: Photographs need to be interpreted and the mode in which they're made affects what they record.

Alan Saunders: This brings us to another question which is when it comes to an observational science like astronomy, whose testimony do we believe? How do we know that we've got the right disciplined and disciplinary, as it were, observer reporting to us?

Simon Schaffer: Yes, one of the problems is that there might be something like a vicious circle here. If an observer reports what his bosses expect, he's often taken to be reliable. If he reports something which is surprising or odd, it may well be his or her observations that are fault. So there's what's called in philosophy, 'a confirmation bias'. That's to say you're more likely to trust people who tell you what you expect there to be.

Now one standard way in which astronomers often deal with this problem, is by trying to multiply the number of observers, by seeing if different observers' testimonies match. And there is another and perhaps even more profound problem there, which is that if two observers don't agree, is it because they've seen different things, or is it because one of them is wrong? The case of observations of comments (sometimes some people could see comments that others could not) the case above all of the real nature of clusters of stars, galaxies, nebulae, deep in space, could they be resolved by powerful telescopes and shown to be stars? Or were they slightly more nearby clouds of luminous gas? Controversies like that are pretty endemic in astronomical sciences.

Alan Saunders: Let's look at a sort of broader view of the philosophy of astronomy as we might call it. One aspect of this is that it does have a close and an ancient relation to chronology, doesn't it?

Simon Schaffer: Yes, one of the most important functions, perhaps in a way the most important function of astronomy is chronological, in the sense that it gives a scale of time. It's why, as one sometimes says, astronomy is the second-oldest profession, since from almost all written cultures, astronomers, or astronomical techniques, are employed by the rulers, the priests, the magistrates, the kings, to set the time-scale of the society and the regime by first of all establishing a calendar which should be correlated to agricultural and economic life, and then over much longer periods, eclipses, the appearance of new stars, which are taken to be significant to humans here on earth.

Now that raises I think some very interesting questions about the political resonance of astronomy. Astronomy is what we might call a Royal science. Astronomy is expensive and difficult, it requires complex and challenging hardware, it requires a certain kind of isolation in that it's very easy to disturb astronomical observations by outside forces. So there's long been a very, very close relationship between astronomy and the State, and between highly visible public institutions of the State and what we might call astronomical ceremonial.

Now that in turn raised a very interesting question which began to be pressing when North Atlantic astronomers, from Britain, France, from the Mediterranean, Jesuit astronomers for example, first encountered other cultural traditions, which had at least as lengthy and at least as accurate, chronological sequences, notably those of South Asia and East Asia, of India and China. And the very interesting and complicated negotiations which then take place from the late 1500s onwards, between European and non-European astronomical traditions, were a really indispensible part of understanding the emergence of imperialism in that period.

Alan Saunders: How does it affect the emergence of imperialism? I presume that these people from the Atlantic world, find an astronomy in these distant places that they can't ignore, that they have to take seriously?

Simon Schaffer: Yes, it's that on the one hand the European astronomers were encountering traditions that were evidently as sophisticated and ancient and invested in fairly precise hardware, as their own. And yet at the same time, the European astronomers were also fairly keen to establish the legitimacy, the greater power, of the European cultural system. So one enterprise which I find fascinating, and which we find repeated in European encounters with Indian astronomy, in European encounters with Chinese astronomy to be sure, is the claim that what is virtuous, valuable, accurate and precise in, for example, Indian astronomy, so it's claimed, is in fact European; that they come from the same source.

And that then the contrast is drawn not between Indian and European astronomical traditions, but between ancient Indian astronomical traditions which are correct and accurate and splendid and share a source with Newtonian astronomy, and what is from the British point of view in this case, currently going on in India, so they say in the 1700s, which has degenerated, which has fallen away.

So it's as if the British are not arriving in India, but returning to it. That they are in a sense, always already there, and that what is virtuous in Indian scientific tradition shares its basis with British scientific tradition, and we see this being worked out by the British astronomers in India from the 1770s well into the 1800s.

Alan Saunders: As we move from the 19th century into the 20th, the observatory takes on a bit more of the appearance of a laboratory. Now what's going on here, and what does that have to do with the imperial project?

Simon Schaffer: From the 1860s and '70s onwards, a whole array of new scientific techniques are invented in Europe. Two in particular matter a great deal: the spectroscope and the camera. Because equipped with these newfangled chemical devices, it was the first time possible not only to tell how far away stars are, and how stars and planets, comets and satellites are moving, but it was possible, so it was claimed, to work out what they're made of. So a new astronomy, that was what it was called, was invented in the second half of the 1800s which involved astronomical chemistry, solar physics, the life of the sun. One of its new leaders, an astronomer called Norman Lockyer, said 'With these devices we can take the sun to pieces'.

But that was a violation, and was felt by many to be a violation of the purity of the isolated observatory. All of a sudden the observatory, having been rather cold and silent and splendid, was now full of Bunsen burners and discharge sparks and had smell and gas. But the pay-off was great. British solar chemists began to watch the surface of the sun to examine the pressure of the solar atmosphere, the behaviour of sunspots, the changes in solar temperature. And some of them argued that there was a very strong correlation between the sunspot cycles, the physico-chemistry of the sun, and the behaviour of weather on earth.

Now that mattered to the British Empire enormously because one of the great challenges was to predict the monsoons in India. It was argued by British Administrators that famines, which became more and more intense, and more and more devastating under British rule in the second half of the 19th century, were essentially natural events. So the British government in India invested an enormous amount of money in the new astronomy. It built a new solar physics observatory in Southern India, and it credited the idea that you could correlate the behaviour of the sun with famine.

Alan Saunders: One of the assumptions of the new astronomy seems to be that whatever the sun and the stars are made of, is going to be the sort of stuff that we have here. So there is an assumption of a homogeneity of matter across the universe.

Simon Schaffer: Yes. Again this may seem to be perhaps bit tautological. If the new astronomy could accurately describe for example, the chemistry of the sun's atmosphere, that meant that the chemistry of the sun is the same as the chemistry of the earth, and vice-versa, we know that's so because we've been so successful at describing the chemistry of the sun. That circle becomes virtuous pretty quickly, so for example the element helium is first discovered in the sun and later discovered on earth. It was spectral lines that convinced these astronomers that they were right to suppose that there's in a certain sense, only one kind of stuff out of which the whole of the universe is made. That's an extraordinary claim. It again was greeted with great controversy.

It's very striking how often theologians and philosophers pointed to the new astronomy as evidence that the universe is one, and that it has one creator. As one of the most important scientists of the period, James Clark Maxwell put it, 'Since we know that atoms in Sirius and atoms on earth are the same, and behave in the same way, it's a bit like being impressed by the fact that shoe sizes are the same everywhere. They're obviously manufactured articles', he argued, 'and if they're obviously manufactured articles there must be a manufacturer.' And Maxwell named that manufacturer, God.

Alan Saunders: So instead of the clock and the clockmaker, we have the shoe and the cobbler, the universal cobbler.

Simon Schaffer, thank you very much for being with us.

Simon Schaffer: Thank you, it's been a great pleasure.

Alan Saunders: Simon Schaffer was here as a guest of the University of Sydney to speak at the Sydney Sawyer Conference on the Atlantic World in a Pacific Field.

The show is produced by Kyla Slaven; the sound engineer is Charlie McKune; I'm Alan Saunders; I'll be back next week.