computation results to nature, or we say compare to experiment or experience, compare it directly with observations to see if it works. If it disagrees with experiment, it’s wrong. In that simple statement is the key to science. It doesn’t make any difference how beautiful your guess is, it doesn’t make any difference how smart you are, who made the guess, or what his name is. If it disagrees with experiment, it’s wrong. That’s all there is to it.’
Why do I like this so much? The reason is that it is modest – almost humble in its simplicity – and this, in my opinion, is the key to the success of science. Science isn’t a grandiose practice; there are no great ambitions to understand why we are here or how the whole universe works or our place within it, or even how the universe began. Just have a look at something – the smallest, most trivial little thing – and enjoy trying to figure out how it works. That is science. In a famous BBC Horizon film broadcast in 1982 called ‘The Pleasure of Finding Things Out’, Feynman went further: ‘People say to me, “Are you looking for the ultimate laws of physics?” No, I’m not. I’m just looking to find out more about the world and if it turns out there is a simple ultimate law which explains everything, so be it; that would be very nice to discover. If it turns out it’s like an onion with millions of layers and we’re just sick and tired of looking at the layers, then that’s the way it is … My interest in science is to simply find out more about the world.’
The remarkable thing about science, however, is that it has ended up addressing some of the great philosophical questions about the origin and fate of the universe and the meaning of existence without actually setting out to do so, and this is no accident. You won’t discover anything meaningful about the world by sitting on a pillar for decades and contemplating the cosmos, although you may become a saint. No, a truly deep and profound understanding of the natural world has emerged more often than not from the consideration of much less lofty and profound questions, and there are two reasons for this. Firstly, simple questions can be answered systematically by applying the scientific method as outlined by Richard Feynman, whereas complex and badly posed questions such as ‘Why are we here?’ cannot. But more importantly, and rather more profoundly, it turns out that the answers to simple questions can overturn centuries of philosophical and theological pontificating quite by accident. Reputations count for naught in the face of observation. The famous story of Galileo’s clashes with the Inquisition at the height of the Copernican debate, which he certainly did not expect (nobody does), is the archetypal example.
Galileo began his university career with the study of medicine, but his imagination was captured by art and mathematics. Between studying Medicine in Pisa and returning to his hometown in 1589 to become Professor of Mathematics, Galileo spent a year in Florence teaching perspective and in particular a technique called chiaroscuro. Chiaroscuro is the study of light and shadow, and how it can be used to create a sense of depth by accurately representing the way that light sources illuminate objects. Chiaroscuro was one of the most important new artistic techniques to emerge during Galileo’s time, allowing a new sense of realism to be portrayed on canvas.
Although Galileo spent only a brief time in Florence, the skills he acquired had a great impact on his scientific work. In particular, his carefully developed ability to understand the delicate play of light on three-dimensional shapes, when applied to his later astronomical studies, played an important role in undermining the Aristotelian cosmological edifice which formed a cornerstone of the teachings of the Roman Catholic Church.
The small and seemingly innocuous theological thread on which Galileo unwittingly tugged was made available to him on a visit to Venice in 1609, when he purchased the lenses required to build his first telescope. One of the first objects he turned his ‘perspective tube’ towards was the Moon. With the mind of a mathematician and the eye of an artist, Galileo drew a series of six watercolours representing what he saw.
These images are both beautiful and revolutionary. Catholic dogma asserted that the Moon and the other heavenly bodies were perfect, unblemished spheres. Previous astronomers who had viewed the Moon, either with the naked eye or through telescopes, had drawn a two-dimensional blotchy surface, but Galileo saw the patterns of light and dark differently. His training in chiaroscuro revealed to him an alien lunar landscape of mountain ranges and craters.
‘I have been led to the conclusion that … the surface of the Moon is not smooth, even and perfectly spherical – as the great crowd of philosophers have believed about this and other heavenly bodies – but, on the contrary, to be uneven and rough and crowded with depression and bulges. And it is like the face of the Earth itself, which is marked here and there with chains of mountains and depths of valleys.’
Galileo shared the watercolours with his long-standing friend from Florence, the artist Cigoli, who was inspired to represent this new and radical view of the Moon in the grandest of settings. Built in the year 430 by Pope Sixtus III, the Pauline Chapel in Rome documents the changing artistic styles and techniques used to represent the natural world across many centuries; a place filled with shifting examples of how the three-dimensional world can be represented on a two-dimensional surface. Covering the dome of the Pauline Chapel is Cigoli’s final masterpiece – a striking fresco depicting a familiar scene of the Virgin Mary bathed in a shaft of golden light surrounded by cherubs and angels. The fresco depicts Mary over what was, for the first time, a detailed, textured and cratered moon. The Vatican named it the Assumption of the Virgin, unaware perhaps of the philosophical challenge it represented. Here was art representing scientific knowledge – a type of knowledge radically different to historical or scriptural authority, based on observation rather than dogma and presented unashamedly in a grand setting for all in Rome to see. It is undoubtedly true that Galileo didn’t intend to challenge the very theological foundations of the Church of Rome by observing the Moon through a telescope. But scientific discoveries, however innocuous they may seem at first sight, have a way of undermining those who don’t much care for facts. Reality catches up with everyone eventually.
With his depictions of the Moon completed, Galileo turned his ever more powerful lenses to other celestial bodies. Between 7 and 13 January 1610, he became the first human to observe Jupiter’s four largest moons – Io, Europa, Ganymede and Callisto – now known as the Galilean Satellites. For Galileo, this was further evidence to support the work of Copernicus and the physical reality of the heliocentric model. If moons were orbiting Jupiter, Galileo reasoned, it was impossible to argue that the Earth was at the centre of the universe, because heavenly bodies existed that did not circle the Earth.
Galileo published these observations in the spring of 1610 in ‘The Starry Messenger’, and from his correspondence with Kepler his irritation with the discontent it caused amongst philosophers was clear. ‘My dear Kepler, I wish that we might laugh at the remarkable stupidity of the common herd. What do you have to say about the principal philosophers of this academy who are filled with the stubbornness of an asp and do not want to look at either the planets, the Moon or the telescope, even though I have freely and deliberately offered them the opportunity a thousand times? Truly, just as the asp stops its ears, so do these philosophers shut their eyes to the light of truth.’
To Galileo’s mind, absolute confirmation of Copernicus’s heliocentric model was provided by his studies of Venus. Beginning in September 1610, Galileo observed Venus over the course of months and, like the Moon, he observed that Venus had phases. Sometimes the planet was lit completely by the Sun, but at other times only a crescent appeared to be illuminated. The only plausible explanation for this observation was that Venus was orbiting the Sun. This was surely final compelling evidence of a solar system with the Sun at its heart and the planets orbiting around it.
It wasn’t that simple, of course. Galileo, in what was certainly an ill-judged move, decided to move beyond reporting his scientific observations and instead champion a particular theological and philosophical interpretation of the data – namely that the Church was wrong and that the Earth was most definitely not the centre of the universe. This he seems to have done because he wanted to be famous, and famous he became. Copernicus’s De revolutionibus
