Prague Pictures: Portraits of a City (21 page)

Rudolf surely suffered a tremor of foreboding when, not long after Kelley's demise, he found himself confronted by yet another outlandish foreigner with a prosthesis. Big blond Tycho of the flowing moustache and metal nose must have seemed a very Viking to the pyknik Emperor. All the more remarkable then that Brahe should have been received at the imperial court with such warmth and generosity. Of course, the Dane had a Europe-wide reputation as an astronomer, but Kelley had been vouched for by Doctor Dee who in turn had been favoured by Elizabeth I.
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Nevertheless, Rudolf was as good as his promise of patronage, and offered to settle Tycho and his extended family in the house of the former pro-chancellor Jacob Kurtz - Kurtz was dead - which Tycho described as 'a splendid and magnificent palace (which [Kurtz] had built in the Italian style, with beautiful private grounds, at a cost of more than 20,000 dalers).' The house stood on the brow of
hill to the west of the palace; it is no longer there, but gigantic statues of Tycho and Kepler have been erected on the site, near the Cernin Palace. Secretary Barwitz showed the Dane over the property, but Tycho was not satisfied, noting that the tower attached to the house would not be large enough to accommodate even one of the astronomical instruments he had brought with him from Hven. Barwitz, no doubt accustomed to the lordly caprices of Rudolf's clients, suggested that perhaps Herr Brahe would prefer to have one of the outlying imperial castles. The choice seems to have been between the Emperor's favourite hunting lodge, Brandys, and a property perched on a hill some forty kilometres or a six-hour carriage ride from the city. Benatky Castle stood in beautiful surroundings above the floodplain of the river Jizera, and was known as 'Bohemian Venice' because when the river was in spate the country round about was under water. Tycho was delighted. At the landlocked heart of Europe, here was another Hven. Before the end of August, the Brahes had moved into Benatky, and Tycho had set up his first instrument.
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At once, Tycho embarked on a lavish rebuilding programme at the Emperor's expense. Within weeks the administrator of the estate, Caspar von Miihlstein, was sending urgent warnings to Barwitz about the mounting cost of the Dane's renovations. It was the beginning of a series of wranglings with imperial officials that would continue to Tycho's death and beyond. To complicate matters, a month after Tycho's move to Benatky there was yet another outbreak of plague in the city and the Emperor had fled the Hradcany for the safety of the countryside. Inevitably the plague reached Benatky, and when the death toll in the area had reached 2,000 Tycho himself - urged, as he loftily pointed out, by his womenfolk, who were frightened he temporarily abandoned the nascent new Uraniborg and retreated thirty kilometers downriver to a castle at Girsitz. He was still there when, at the beginning of 1600, Johannes Kepler arrived in Prague, and thus there was a delay to one of the most momentous meetings in the history of science.

It would be hard to imagine two more dissimilar figures than Kepler and Tycho Brahe. Kepler, the younger of the two by twenty-five years, was born in 1571 - at 2.30 pm on December 27th of that year, to be precise, which Kepler liked to be - on the northern fringes of the Black Forest, in the town of Weilderstadt, a 'free city' within the duchy of Wurttemberg. The family were a mixed lot; Grandfather Sebald was for a time Biirghermeister of Weilderstadt, while his son Sebaldus was, in Johannes Kepler's laconic description of him, 'an astrologer, a Jesuit, acquired a wife, caught the French sickness, was vicious.' Kepler's father, a professional mercenary, was a braggart and a bully who cruelly mistreated his wife and children, eventually abandoning them altogether to go off to the Low Countries to fight with the Duke of Alba's marauders. The mother, Katarina, was quick-witted but cold; like her son, she was fascinated by the natural world, although her interest in herbs and homemade medicines would eventually lead to her being tried on a charge of witchcraft. Johannes was a sickly child, made sicklier by being sent out to work as a farm labourer at the age of eight. Eventually he was put back to school, and received an excellent education thanks to the enlightened policies of the Duke of Wurttemberg. At seventeen he entered the University of Tubingen, where he was taught by the famous Michael Mastlin, a mathematician and astronomer admired even by the great Tycho Brahe.

Kepler was both a devout Protestant and a follower of Pythagoras - the philosopher of the fifth century BC who taught that the universe is centred not on the Earth but on an eternal, invisible flame - and held to the revolutionary theory of Copernicus, who had set the sun at the focus of planetary motion. These were daring beliefs for a young man to hold in those times of religious upheaval and repression.
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He also read widely in the work of the Neoplatonists, and of the mystic and philosopher Cardinal Nicholas of Cusa, who had anticipated Copernicus by a century by declaring that the Earth does not stand still at the centre of the world. From Tubingen in his third year Kepler was directed by the university authorities to take up the post of schoolteacher in Graz in southern Austria. Kepler was aghast at the prospect of being buried alive in the far-off and backward province of Styria; even to get there he would lose ten days because of the different calendar in use in Graz. Nevertheless he bowed to authority, and took up his post at the seminary school in 1594, at the age of twenty-two. His subjects were advanced mathematics, including astronomy. He was a terrible teacher: in his first year he had a handful of students, in his second, none. He also held the position of District Mathematician, which, despite the high sound of it, meant he would be required chiefly to draw up astrological predictions for the town and district at the beginning of each new year. Kepler maintained an ambivalent attitude to astrology, the 'foolish little daughter' of astronomy, as he called it, yet throughout his life he continued to cast horoscopes for himself and his family, especially his children. He took great care with these star charts, while being not at all averse to massaging the data in order to avoid unfavourable predictions.

Kepler recorded the moment, on July 19th, 1595, when his life as a scientist may be said truly to have begun. He was in the classroom of the Graz seminary school, conducting a lesson in astronomy. He had drawn on the blackboard a diagram illustrating the progression of the great conjunctions of Jupiter and Saturn, that is, the crossing points at which, approximately every twenty years, the planet Jupiter catches up with and passes Saturn. Because of slight variations in distance between the points on the Zodiac at which the conjunctions occur - pay attention, please, this is really not as complicated as it seems - it is possible to inscribe a series of triangles within the circle of the Zodiac joining the conjunction points, triangles which on their inner sides will, as if by magic, or divine intention, 'draw' another, smaller circle . . . Oh, all right, here is an illustration.

For years already Kepler the astronomer had been pondering essential questions, such as why there should be six planets - only six were known in his day - and why the distances between their orbits should be set as they are. There must be a plan, a rational design; as Einstein centuries later would insist, God does not play dice with the world.
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To Kepler the Pythagorean, the planetary system was a gigantic musical instrument sounding its vast, silent chord in tune to the geometric laws of harmony. It was a conviction he shared with most astronomers back to antiquity. Kepler's genius, his astonishing originality, lay in the way he tackled the questions that he never stopped asking. Before him, cosmologists had bent their best efforts to describing the disposition of things as they seemed, and predicting accurately how things might be expected to be in the future. Kepler was the first to concentrate not on description, but explanation. He wanted to know not only how things are as they are, but why. A plan, a pattern, there must be.

That day in the schoolroom in Graz when he stepped back from the blackboard - let us imagine the summer sunlight in the dusty window, the chalk-motes drifting in the luminous air, the bored pupils drooping at their desks, one of them dreamily picking his nose - what Kepler saw was that the inner circle was half the size of the outer one. Saturn and Jupiter were the two outermost planets of the solar system, as it was known to him, and Jupiter's orbit was roughly half the size of Saturn's. Was the relationship between them dictated by a triangle, the first figure in geometry? And if so, could the relations between the orbits of the remaining planets also be set according to the dimensions of other geometrical forms? He spent the rest of the summer trying to discover what these forms might be, juggling triangles and squares and pentagons, like Beckett's Molloy shuffling his sucking stones from pocket to pocket. And at last it came to him, when he saw that of course he must move from two to three dimensions. In geometry there are five, and only five, regular or perfect solids, from the cube, with six identical sides, up to the icosahedron, which has twenty sides. It is a characteristic of these shapes that they can be set within a sphere so that all their corners touch the surface of the sphere, and that a sphere can be set inside them so that the surface of the sphere will touch the centre of every side. Perfection. This was it, Kepler believed, God's big secret, the framework of the planetary system, the grid of the great world. This was why there are, as he thought, six planets, because the Lord of the Universe had founded the solar system on the five perfect solids, one set inside each of the planetary orbits, with the sun at the centre.

Kepler's model of the universe, from
Mysteriwn Cosmograpicum

Kepler was to devote the rest of his life to proving his theory, despite the fact that it was unprovable, because mistaken. Even after he had made the momentous discovery that the planets do not move in perfect circles, but in ellipses, and had devised his three laws of planetary motion which revolutionised astronomy and the science of physics, he still clung to his beautiful idea, resorting to some shameless mathematical sleight of hand in his efforts to smooth out the inconsistencies. In the summer of 1595, however, in the first flush of discovery, his immediate need was for the most accurate planetary observations then available. He thought at once of Tycho Brahe. However, it would be more than four years before he would meet the Dane, and even then it took another year and a half, and Tycho's death, for this 'little house dog', as he liked to describe himself, to get his teeth into the juicy meat of Tycho's planetary charts. By then he was a married man with a stepdaughter - his wife, Barbara, twenty-three when he met her, was already twice a widow - and the author of a book setting out his theory of the heavens, with the catchy title
Prodromus dissertationum cosmographicarum, continens mysterium cosmographicum, de admirabili proportione orbium coelestium, deque causis coelorum numeri, mag-nitudinis, motuumque periodicorum genuinis &
proprijis, demonstratum, per quinque regularia corpora geometrica,
or
Mysterium cosmographi-cum
for short.