Big Bang

6. The apparent annual sequence of movements of the Sun is a result of the Earth’s revolution around it. All the planets revolve around the Sun.

7. The apparent retrograde motion of some of the planets is merely the result of our position as observer on a moving Earth.

Copernicus’s axioms were spot on in every respect. The Earth does spin, the Earth and the other planets do go around the Sun, this does explain the retrograde planetary orbits, and failure to detect any stellar parallax was due to the remoteness of the stars. It is not clear what motivated Copernicus to formulate these axioms and break with the traditional world-view, but perhaps he was influenced by Domenico Maria de Novara, one of his professors in Italy. Novara was sympathetic to the Pythagorean tradition, which was at the root of Aristarchus’ philosophy, and it was Aristarchus who had first posited the Sun-centred model 1,700 years earlier.

The Commentariolus was a manifesto for an astronomical mutiny, an expression of Copernicus’s frustration and disillusionment with the ugly complexity of the ancient Ptolemaic model. Later he would condemn the makeshift nature of the Earth-centred model: ‘It is as though an artist were to gather the hands, feet, head and other members for his images from diverse models, each part excellently drawn, but not related to a single body, and since they in no way match each other, the result would be a monster rather than a man.’ Nevertheless, despite its radical contents, the pamphlet caused no ripples among the intellectuals of Europe, partly because it was read by so few people and partly because its author was a minor canon working on the fringes of Europe.

Copernicus was not dismayed, for this was only the start of his efforts to transform astronomy. After his uncle Lucas died in 1512 (having quite possibly been poisoned by the Teutonic Knights, who had described him as ‘the devil in human shape’), he had even more time to pursue his studies. He moved to Frauenburg Castle, set up a small observatory and concentrated on fleshing out his argument, adding in all the mathematical detail that was missing in the Commentariolus.

Copernicus spent the next thirty years reworking his Commentariolus, expanding it into an authoritative two-hundred-page manuscript. Throughout this prolonged period of research, he spent a great deal of time worrying about how other astronomers would react to his model of the universe, which was fundamentally at odds with accepted wisdom. There were often days when he even considered abandoning plans to publish his work for fear that he would be mocked far and wide. Moreover, he suspected that theologians would be wholly intolerant to what they would perceive as sacrilegious scientific speculation.

He was right to be concerned. The Church later demonstrated its intolerance by persecuting the Italian philosopher Giordano Bruno, who was part of the generation of dissenters that followed Copernicus. The Inquisition accused Bruno of eight heresies, but the existing records do not specify them. Historians think that it is likely that Bruno had offended the Church by writing On the Infinite Universe and Worlds, which argued that the universe is infinite, that stars have their own planets and that life flourishes on these other planets. When condemned to death for his crimes, he responded: ‘Perchance you who pronounce my sentence are in greater fear than I who receive it.’ On 17 February 1600, he was taken to Rome’s Campo dei Fiori (Field of Flowers), stripped naked, gagged, tied to a stake and burned to death.

Copernicus’s fear of persecution could have meant a premature end to his research, but fortunately a young German scholar from Wittenberg intervened. In 1539, Georg Joachim von Lauchen, known as Rheticus, travelled to Frauenburg to seek out Copernicus and find out more about his cosmological model. It was a brave move, because not only was the young Lutheran scholar facing an uncertain welcome in Catholic Frauenburg, but also his own colleagues were not sympathetic to his mission. The mood was typified by Martin Luther, who kept a record of dinner-table conversation about Copernicus: ‘There is talk of a new astronomer who wants to prove that the Earth moves and goes around instead of the sky, the Sun and the Moon, just as if somebody moving in a carriage or ship might hold that he was sitting still and at rest while the ground and the trees walked and moved… The fool wants to turn the whole art of astronomy upside-down.’

Luther called Copernicus ‘a fool who went against Holy Writ’, but Rheticus shared Copernicus’s unshakeable confidence that the route to celestial truth lay with science rather than Scripture. The sixty-six-year-old Copernicus was flattered by the attentions of the twenty-five-year-old Rheticus, who spent three years at Frauenburg reading Copernicus’s manuscript, providing him with feedback and reassurance in equal measure.

By 1541, Rheticus’s combination of diplomatic and astronomical skills was sufficient for him to obtain Copernicus’s blessing to take the manuscript to the printing house of Johannes Petreius in Nuremberg for publication. He had planned to stay to oversee the entire printing process, but was suddenly called away to Leipzig on urgent business, and so handed responsibility for supervising publication to a clergyman by the name of Andreas Osiander. At last, in the spring of 1543, De revolutionibus orbium cælestium (‘On the Revolutions of the Heavenly Spheres’) was finally published and several hundred copies were on their way to Copernicus.

Meanwhile, Copernicus had suffered a cerebral haemorrhage at the end of 1542, and was lying in bed, fighting to stay alive long enough to set eyes on the finished book that contained his life’s work. Copies of his treatise reached him just in time. His friend Canon Giese wrote a letter to Rheticus describing Copernicus’s plight: ‘For many days he had been deprived of his memory and mental vigour; he only saw his completed book at the last moment, on the day he died.’

Copernicus had completed his duty. His book offered the world a convincing argument in favour of Aristarchus’ Sun-centred model. De revolutionibus was a formidable treatise, but before discussing its contents it is important to address two perplexing mysteries surrounding its publication. The first of these relates to Copernicus’s incomplete acknowledgements. The introduction to De revolutionibus mentioned several people, such as Pope Paul III, the Cardinal of Capua and the Bishop of Kulm, yet there was no mention of Rheticus, the brilliant apprentice who had played the vital role of midwife to the birth of the Copernican model. Historians are baffled as to why his name was omitted and can only speculate that crediting a Protestant might have been looked upon unfavourably by the Catholic hierarchy which Copernicus was trying to impress. One consequence of this lack of acknowledgement was that Rheticus felt snubbed and would have nothing more to do with De revolutionibus after its publication.

The second mystery concerns the preface to De revolutionibus, which was added to the book without Copernicus’s consent and which effectively retracted the substance of his claims. In short, the preface undermined the rest of the book by stating that Copernicus’s hypotheses ‘need not be true or even probable’. It emphasised ‘absurdities’ within the Sun-centred model, implying that Copernicus’s own detailed and carefully argued mathematical description was nothing more than a fiction. The preface does admit that the Copernican system is compatible with observations to a reasonable degree of accuracy, but it emasculates the theory by stating that it is merely a convenient way to do calculations, rather than an attempt to represent reality. Copernicus’s original handwritten manuscript still exists, so we know that the original opening was quite different in tone from the printed preface that trivialised his work. The new preface must therefore have been inserted after Rheticus had left Frauenburg with the manuscript. This would mean that Copernicus was on his deathbed when he first read it, by which time the book had been printed and it was too late to make any changes. Perhaps it was the very sight of the preface that sent him to his grave.

Figure 10 This diagram from Copernicus’s De revolutionibus illustrates his revolutionary view of the universe. The Sun is firmly at the hub and is orbited by the planets. Earth itself is orbited by the Moon and is correctly located between the orbits of Venus and Mars.

So who wrote and inserted the new preface? The main suspect is Osiander, the clergyman who took on responsibility for publication when Rheticus left Nuremberg for Leipzig. It is likely that he believed that Copernicus would suffer persecution once his ideas became public, and he probably inserted the preface with the best of intentions, hoping that it would assuage critics. Evidence for Osiander’s concerns can be found in a letter to Rheticus in which he mentions the Aristotelians, meaning those who believed in the Earth-centred view of the world: ‘The Aristotelians and theologians will easily be placated if they are told that … the present hypotheses are not proposed because they are in reality true, but because they are the most convenient to calculate the apparent composite motions.’

But in his intended preface, Copernicus had been quite clear that he was willing to adopt a defiant stance against his critics: ‘Perhaps there will be babblers who, although completely ignorant of mathematics, nevertheless take it upon themselves to pass judgement on mathematical questions and, badly distorting some passages of Scripture to their purpose, will dare find fault with my undertaking and censure it. I disregard them even to the extent of despising their criticism as unfounded.’

Having finally plucked up the courage to publish the single most important and controversial breakthrough in astronomy since the ancient Greeks, Copernicus tragically died knowing that Osiander had misrepresented his theories as nothing more than artifice. Consequently, De revolutionibus was to vanish almost without trace for the first few decades after its publication, as neither the public nor the Church took it seriously. The first edition did not sell out, and the book was reprinted only twice in the next century. In contrast, books promoting the Ptolemaic model were reprinted a hundred times in Germany alone during the same period.

However, Osiander’s cowardly and conciliatory preface to De revolutionibus was only partly to blame for its lack of impact. Another factor was Copernicus’s dreadful writing style, which resulted in four hundred pages of dense, complex text. Worse still, this was his first book on astronomy, and the name Copernicus was not well known in European scholarly circles. This would not have been disastrous, except that Copernicus was now dead and could not promote his own work. The situation could possibly have been rescued by Rheticus, who might have championed De revolutionibus, but he had been snubbed and no longer wished to be associated with the Copernican system.

Moreover, just like Aristarchus’ original incarnation of the Sun-centred model, De revolutionibus was dismissed because the Copernican system was less accurate than Ptolemy’s Earth-centred model when it came to predicting future positions of the planets: in this respect the basically correct model was no match for its fundamentally flawed rival. There are two reasons for this strange state of affairs. First, Copernicus’s model was missing one vital ingredient, without which its predictions could never be sufficiently accurate to gain its acceptance. Second, Ptolemy’s model had achieved its degree of accuracy by tinkering with all the epicycles, deferents, equants and eccentrics, and almost any flawed model can be rescued if such fiddle-factors are introduced.

And, of course, the Copernican model was still plagued with all the problems that had led to the abandonment of Aristarchus’ Sun-centred model (see Table 2, pp. 34—5). In fact, the only attribute of the Sun-centred model that made it clearly better than the Earth-centred model was still its simplicity. Although Copernicus did toy with epicycles, his model essentially employed a simple circular orbit for each planet, whereas Ptolemy’s model was inordinately complex, with its finely tuned epicycles, deferents, equants and eccentrics for each and every planet.

Fortunately for Copernicus, simplicity is a prized asset in science, as had been pointed out by William of Occam, a fourteenth-century English Franciscan theologian who became famous during his lifetime for arguing that religious orders should not own property or wealth. He propounded his views with such fervour that he was run out of Oxford University and had to move to Avignon in the south of France, from where he accused Pope John XII of heresy. Not surprisingly, he was excommunicated. After succumbing to the Black Death in 1349, Occam became famous posthumously for his legacy to science, known as Occam’s razor, which holds that if there are two competing theories or explanations, then, all other things being equal, the simpler one is more likely to be correct. Occam put it thus: pluralitas non est ponenda sine necessitate (‘plurality should not be posited without necessity’).

Imagine, for instance, that after a stormy night you come across two fallen trees in the middle of a field, and there is no obvious sign of what caused them to fall. The simple hypothesis would be that the trees were blown over by the storm. A more complicated hypothesis might be that two meteorites simultaneously arrived from outer space, each ricocheting off one tree, felling the trees in the process, and then the meteorites collided head on with each other and vaporised, thereby accounting for the lack of any material evidence. Applying Occam’s razor, you decide that the storm, rather than the twin meteorites, is the more likely explanation because it is the simpler one. Occam’s razor does not guarantee the right answer, but it does usually point us towards the correct one. Doctors often rely on Occam’s razor when diagnosing an illness, and medical students are advised: ‘When you hear hoof beats, think horses, not zebras.’ On the other hand, conspiracy theorists despise Occam’s razor, often rejecting a simple explanation in favour of a more convoluted and intriguing line of reasoning.

Occam’s razor favoured the Copernican model (one circle per planet) over the Ptolemaic model (one epicycle, deferent, equant and eccentric per planet), but Occam’s razor is only decisive if two theories are equally successful, and in the sixteenth century the Ptolemaic model was clearly stronger in several ways; most notably, it made more accurate predictions of planetary positions. So the simplicity of the Sun-centred model was considered irrelevant.

And for many people the Sun-centred model was still too radical even to be contemplated, so much so that Copernicus’s work may have resulted in a new meaning for an old word. One etymological theory claims that the word ‘revolutionary’, referring to an idea that is completely counter to conventional wisdom, was inspired by the title of Copernicus’s book, ‘On the Revolutions of the Heavenly Spheres’. And as well as revolutionary, the Sun-centred model of the universe also seemed completely impossible. This is why the word köpperneksch, based on the German form of Copernicus, has come to be used in northern Bavaria to describe an unbelievable or illogical proposition.

All in all, the Sun-centred model of the universe was an idea ahead of its time, too revolutionary, too unbelievable and still too inaccurate to win any widespread support. De revolutionibus sat on a few bookshelves, in a few studies, and was read by just a few astronomers. The idea of a Sun-centred universe had first been suggested by Aristarchus in the fifth century BC, but it was ignored; now it had been reinvented by Copernicus, and it was being ignored again. The model would go into hibernation, waiting for somebody to resuscitate it, examine it, refine it and find the missing ingredient that would prove to the rest of the world that the Copernican model of the universe was the true picture of reality. Indeed, it would be left to the next generation of astronomers to find the evidence that would show that Ptolemy was wrong and that Aristarchus and Copernicus were right.

Castle of the Heavens

Born into the Danish nobility in 1546, Tycho Brahe would earn lasting fame among astronomers for two particular reasons. First, in 1566, Tycho became embroiled in a disagreement with his cousin Manderup Parsberg, possibly because Parsberg had insulted and mocked Tycho over a recent astrological prediction that had fallen flat. Tycho had foretold the death of Suleiman the Great, and even embedded his prophecy within a Latin poem, apparently unaware that the Ottoman leader had already been dead for six months. The dispute culminated in an infamous duel. During the sword fight, a slash from Parsberg cut Tycho’s forehead and hacked through the bridge of his nose. An inch deeper and Tycho would have died. Thereafter he glued into place a false metal nose, so cleverly composed of a gold-silver–copper alloy that it blended in with his skin tone.

The second and more important reason for Tycho’s fame was that he took observational astronomy to an entirely new level of accuracy. He earned such a high reputation that King Frederick II of Denmark gave him the island of Hven, 10 km off the Danish coast, and paid for him to build an observatory there. Uraniborg (Castle of the Heavens) would grow over the years into a vast ornate citadel that consumed more than 5% of Denmark’s gross national product, an all-time world record for research centre funding.

Uraniborg housed a library, a paper mill, a printing press, an alchemist’s laboratory, a furnace and a prison for unruly servants. The observation turrets contained giant instruments, such as sextants, quadrants and armillary spheres (all naked-eye instruments, as astronomers had not yet learned to exploit the potential of lenses). There were four sets of every instrument for simultaneous and independent measurements, thereby minimising errors in assessing the angular positions of stars and planets. Tycho’s observations were generally accurate to

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°, five times better than the best previous measurements. Perhaps Tycho’s measurements were aided by his ability to remove his nose and align his eye more perfectly.

Figure 11 Uraniborg, on the island of Hven, the best funded and most hedonistic astronomical observatory in history.

Tycho’s reputation was such that a stream of VIPs visited his observatory. As well as being interested in his research, these visitors were also attracted by Uraniborg’s wild parties, which were famous all over Europe. Tycho provided alcohol in excess and entertainment in the shape of mechanical statues and a story-telling dwarf called Jepp, who was said to be a gifted clairvoyant. To add to the spectacle, Tycho’s pet elk was allowed to freely wander the castle, but tragically it died after stumbling down a staircase after drinking too much alcohol. Uraniborg was more like the setting for a Peter Greenaway film than a research institute.

While Tycho had been raised in the traditions of Ptolemaic astronomy, his painstaking observations forced him to reconsider his confidence in the ancient view of the universe. In fact, we know that he had a copy of De revolutionibus in his study and that he was sympathetic to Copernicus’s ideas, but, instead of adopting them unreservedly, he developed his own model of the universe, which was a faint-hearted halfway house between Ptolemy and Copernicus. In 1588, almost fifty years after Copernicus’s death, Tycho published De mundi ætherei recentioribus phænomenis (‘Concerning the New Phenomena in the Ethereal World’), in which he argued that all the planets orbited the Sun, but that the Sun orbited the Earth, as shown in Figure 12. His liberalism stretched as far as allowing the Sun to be the hub for the planets, but his conservatism obliged him to retain the Earth at the centre of the universe. He was reluctant to dislodge the Earth, because its supposed centrality was the only way to explain why objects fall towards the centre of the Earth.

Figure 12 Tycho’s model makes the same error as Ptolemy’s and places the Earth at the centre of the universe, being orbited by the Moon and the Sun. His main breakthrough was to realise that the planets (and the fiery comet) orbit the Sun. This illustration is from Tycho’s De mundi ætherei.

Before Tycho could continue to the next stage of his programme of astronomical observation and theorising, his research suffered a severe blow. His patron, King Frederick, died after a session of binge drinking in the same year that Tycho published De mundi ætherei, and the new king, Christian IV, was no longer prepared to fund Tycho’s lavish observatory or tolerate his hedonistic lifestyle. Tycho had no option but to abandon Uraniborg and leave Denmark with his family, assistants, Jepp the dwarf and cartloads of astronomical equipment. Fortunately, Tycho’s instruments had been designed to be transportable, because he had shrewdly realised: ‘An astronomer must be cosmopolitan, because ignorant statesmen cannot be expected to value their services.’

Tycho Brahe migrated to Prague, where Emperor Rudolph II appointed him Imperial Mathematician and allowed him to establish a new observatory in Benatky Castle. The move turned out to have a silver lining, because it was in Prague that Tycho teamed up with a new assistant, Johannes Kepler, who would arrive in the city a few months later. The Lutheran Kepler had been forced to flee his previous home in Graz when the fiercely Catholic Archduke Ferdinand had threatened to execute him, in keeping with his stated declaration that he would rather ‘make a desert of the country than rule over heretics’.

Fittingly, Kepler set out on his journey to Prague on 1 January 1600. The start of a new century would mark the start of a new collaboration that would lead to a reinvention of the universe. Together, Tycho and Kepler made the perfect double act. Scientific advance requires both observation and theory. Tycho had accumulated the best collection of observations in the history of astronomy, and Kepler would prove to be an excellent interpreter of those observations. Although Kepler suffered from myopia and multiple vision from birth, he would ultimately see farther than Tycho.

It was a partnership that was formed in the nick of time. Within a few months of Kepler’s arrival, Tycho attended a dinner hosted by the Baron of Rosenberg and drank to his usual excess, refusing nonetheless to break etiquette by leaving the table before the Baron. Kepler recorded: ‘When he drank more, he felt the tension in his bladder increase, but he put politeness before his health. When he got home, he was scarcely able to urinate.’ That night he developed a fever, and from then on he alternated between bouts of unconsciousness and delirium. Ten days later he was dead.

On his deathbed, Tycho repeatedly uttered the phrase: ‘May I not have lived in vain.’ There was no need to fear, because Kepler would guarantee that Tycho’s meticulous observations bore fruit. In fact, it is quite possible that Tycho had to die in order for his work to flourish, because while he was alive he carefully guarded all his notebooks and never shared his observations, always dreaming of publishing a solo masterwork. Tycho certainly never considered embracing Kepler as an equal partner – he was, after all, a Danish aristocrat, whereas Kepler was a mere peasant. However, seeing the deeper meaning of his own observations was beyond Tycho, and required the skills of a trained mathematician such as Kepler.

Kepler was born into a lowly family that struggled to survive the upheavals caused by war, religious strife, a wayward criminal father and a mother who had been exiled after accusations of witchcraft. Not surprisingly, he grew up as an insecure hypochondriac with little self-esteem. In his own self-deprecating horoscope, written in the third person, he described himself as a little dog:

He likes gnawing bones and dry crusts of bread, and is so greedy that whatever his eyes chance on he grabs; yet, like a dog, he drinks little and is content with the simplest food… He continually seeks the goodwill of others, is dependent on others for everything, ministers to their wishes, never gets angry when they berate him and is anxious to get back into their favour… He has a dog-like horror of baths, tinctures and lotions. His recklessness knows no limits, which is surely due to Mars in quadrature with Mercury and in trine with the Moon.

His passion for astronomy seems to have been his only respite from self-loathing. At the age of twenty-five he wrote Mysterium cosmographicum, the first book to defend Copernicus’s De revolutionibus. Thereafter, convinced of the veracity of the Sun-centred model, he dedicated himself to identifying just what it was that made it inaccurate. The greatest error was in predicting the exact path of Mars, a problem that had plagued Copernicus’s assistant, Rheticus. According to Kepler, Rheticus had been so frustrated with his failure to solve the Mars problem that ‘he appealed as a last resort to his guardian angel as an Oracle. The ungracious spirit thereupon seized Rheticus by the hair and alternately banged his head against the ceiling, then let his body down and crashed it against the floor.’

With access at last to Tycho’s observations, Kepler was confident that he could solve the problem of Mars and remove the inaccuracies in the Sun-centred model within eight days; in fact, it took him eight years. It is worth stressing the amount of time that Kepler spent perfecting the Sun-centred model– eight years!– because the brief summary that follows could easily underplay his immense achievement. Kepler’s eventual solution was the result of arduous and tortuous calculations that filled nine hundred folio pages.

Kepler made his great breakthrough by jettisoning one of the ancient tenets, namely that the planets all move in paths that are circles or combinations of circles. Even Copernicus had clung loyally to this circular dogma, and Kepler pointed out that this was just one of Copernicus’s flawed assumptions. In fact, Kepler claimed that his predecessor had wrongly assumed the following three points:

1. the planets move in perfect circles,

2. the planets move at constant speeds,

3. the Sun is at the centre of these orbits.

Although Copernicus was right in stating that the planets orbit the Sun and not the Earth, his belief in these three false assumptions sabotaged his hopes of ever predicting the movements of Mars and the other planets with a high degree of accuracy. However, Kepler would succeed where Copernicus had failed because he discarded these assumptions, believing that the truth emerges only when all ideology, prejudice and dogma are set aside. He opened his eyes and mind, took Tycho’s observations as his rock and built his model upon Tycho’s data. Gradually an unbiased model of the universe began to emerge. Sure enough, Kepler’s new equations for the orbits matched the observations, and the Solar System took shape at last. Kepler exposed Copernicus’s errors, and showed that:

1. the planets move in ellipses, not perfect circles,