Copernicus’s Theory

Feature, Middle Ages

The Earth No Longer the Centre of the Universe

Near the high altar in the University Church of St Ann in the Polish city of Krakow, there are two inscriptions. One of them, in Latin, says simply, “Nicholas Copernicus, the ornament, the honor and the glory of his country, his city, and his university”. The other reads, in Polish, the language of Copernicus.

“Polskie wydalo go plemie Wstrzymal alonce, wzruszyl ziemie.”

And this tells us why the name Copernicus is held in awe among scientists all over the world, though he died four hundred years ago. Freely translated, it reads, “He asked the sun to stop. And when it did, the earth began to spin. Yet he is Poland’s, Poland nourished him,”

From the earliest days men had looked at the sky and wondered. “In the beginning”, says the Book of Genesis, “God created the heaven and the earth.” And a little further on, “God made two great lights; the greater light to rule the day and the lesser light to rule the night: he made stars also. And God set them in the firmament of the heaven to give light upon the earth.”

So that was the reason. But there were questions still unexplained. When man first blinked at the entrance to his cave, shielded his eyes from the rising sun in the east, he became aware that the sun moved. There was no doubt about it. Whether the thing was only a lamp held high by some invisible hand, whether it was a peephole in the sky, a puncture in the blue firmament, letting in light from some all-embracing heaven, or whether it was a god in a golden chariot, it moved.

At the start of its run, when it was near to the earth, when its golden shape, like an orange which has fallen from its tree into the water and rises slowly to the surface, was lifting above the horizon, one could see it moving. See, it was tangled in the branches of that tree. No, it was breaking loose, it was rising, and it had cleared the tree. It was on its own, moving slowly, definitely, into the sky. After this, one tended to lose interest, it was up there, somewhere, providing light for the tasks of the day, but unless one craned one’s neck, one never saw it. Until evening. Then the sun sank, quite visibly, back into its pool of darkness, but at the other end of the horizon; it sank, not through the branches of the same tree, but in a different place.

And the next morning it rose again, not exactly in the same place. Unless someone had moved the tree in the night, the sun had moved its pathway a few inches. Now it rose, not through the branches, but beside them.

In the second century after Christ, the Greek astronomer Ptolemy produced his own theory. A little startling at first, but it needed only the testimony of the senses to make one realize that it must hold the only possible answer to the mystery of the skies. There is no doubt, said Ptolemy, that the earth is a huge lump of matter in the exact centre of the universe, at the centre of everything. The sun, the moon, the stars, all these revolve unceasingly around it. They change their positions, hour by hour, and this is the reason. We are the centre of the universe, everything goes round us.

It was plausible; it seemed, when one thought about it, absolutely unshakeable. And it was pleasantly flattering to man. Round and round went these heavenly bodies: and if it were not at man’s bidding, at least it was on his behalf; shedding their different radiance to light his day, his night, point the way for his journeys to north, south, east or west.

This delightful theory met no successful opposition for fourteen hundred years.

Then, in February of 1473, Nicholas Copernicus was born in the Polish town of Torun, on the River Vistula. Nowadays it has thriving industries: there are engineering works, chemical works, and textile factories. But it is famous for Copernicus. At the age of eighteen he went from there to the ancient Polish University of Krakow where he studied astronomy, under the Ptolemaic system. From Krakow he went to Italy, where he studied canon law, out of consideration for his uncle, Bishop Lucas, who wished to make him a priest: Copernicus had no intention of becoming a priest, but this was a courteous halfway measure.

He continued, at Bologna University, his studies of the sun and stars and, with them, mathematics. By the turn of the century, in 1500, we find him lecturing in Rome on both these subjects. He was fortunate in being able to observe an eclipse of the moon while he was there. Then, for he was a man of parts, he went on to study medicine at the University of Padua, while finishing studies for his doctor’s degree in canon law.

Now at the age of thirty-two he settled, as his uncle the Bishop had urged him to do, in the bishopric of Varmia, where he became his uncle’s physician and personal secretary. He devoted a great deal of his time to healing the poor and dealing with the Bishop’s correspondence, while at the same time he recruited and trained soldiers to resist the German “Knights of the Teutonic Order” who made periodic raids into Poland.

It was here, in Ermeland, in the intervals of fighting battles, healing the sick and administering church property, that Nicholas Copernicus found time to observe and tabulate the data which revolutionized man’s thinking about the world and its neighbours. Shortly before he died in 1543, still working in Ermeland, his book De Revolutionibus Orbium Coelestium was published. It stated, quite clearly, that the earth was not the centre of things. The sun was the centre of a planetary system, had a number of smaller “planets” moving round it: and the earth was only one of these, and by no means the largest. Far from being stationary and central, the earth was in a huge “orbit”, millions of miles from the sun, travelling at a great speed.

The theory was, in every sense, incredible. As Dr Dorothy Stimson says in her study of Copernicus and the gradual, painful acceptance of his idea: “It is a triumph of reason and imagination; and with its almost complete independence of authority, is perhaps as original a work as a human being may be expected to produce.’ But the publication, long delayed, was a small tragedy. Copernicus, audacious as a thinker, physically brave, was timid over his theories. He was a good churchman and he sensed that the Church would take exception to this revolutionary theory “concerning the revolutions of the heavenly spheres”. Who was Copernicus, indeed, to meddle with Heaven itself? He delayed for years, checking and rechecking data and calculations, before agreeing to publish the work. As he admits in his preface, explaining the delay: “The scorn which was to be feared on account of the novelty and absurdity of the opinion impelled me for that reason to set aside entirely the book already drawn up.”

But he was an honest man and he refused to write, as he had been advised, an introduction explaining that the new system was merely a hypothesis, useful for calculations but not necessarily true. He was ageing fast, his eyes were growing dim, and thus he was unable to see, when the first copy appeared from the printer in Nuremberg, that someone else, meaning well, no doubt, had written the introduction for him.

Because of this disarming foreword, the Church turned a blind eye, failed to realize the theory’s significance, and only did so in 1616, many years after its author’s death. Then, with much-belated haste, it put De Revolutionibus on its forbidden index, where it remained until 1835.

The Catholic Church, so slow to recognize the character of Copernicus’s discovery, made no attempt to decry it, to persecute those who might be tempted to believe it, whereas the new religious reformers were less tolerant. Martin Luther made fiery speeches denouncing the mad Pole, “The New Astrologer, who would overturn the whole system of astronomy.”

Luther was right: the theory did overturn astronomy, though it took more than a hundred and fifty years for it to be accepted in the Universities, and generations more before the common people were prepared to accept it.

The heliocentric theory, that the sun was the centre of our planetary system, was a complete departure from previous thinking on the subject, and although we accept it without question to-day, it is easy to see why it was regarded with fear, even horror. All the evidence of one’s senses argues against it. But once it had been accepted it revolutionized scientific thinking.

Kepler, Galileo and others developed the theory until it was completed by Newton. Without it, Kepler would not have been able to discover the true form of the planetary orbits: the concept of universal gravitation (the well-known apple landing on Isaac Newton’s head) would have been impossible without a heliocentric viewpoint. Without a realization that each heavenly body has its own gravity, depending on its mass, partially countered, for those who reside upon it, by the centrifugal force of that body’s rotation, and that there is no gravity elsewhere, it is unlikely that anyone would, for example, have considered space travel: no satellite or projectile would be able to withstand a constant force of gravity.

Copernicus had ideas which extended far beyond what we now call the solar system, that system of planets, some with satellites around them, all moving round the sun: and we now know that the sun and its solar system are only a minute part of an infinite universe, with other, far larger, systems, revolving around other far larger stars. For the sun, as astronomers soon realized, is only a star, and an inferior one at that, around which we move, in orbit, at a distance of only 93,000,000 miles.

Most distances in space, from star to star, system to system, are far too vast to be expressed in this way; they have to be set out in “light years”. Light travels at 300,000,000 metres (or 186,000 miles) in every second of time. It takes, for example, eight and a half minutes to reach us from the sun; if the sun went out, it would be eight and a half minutes before we knew. The distance which light could travel in one year is obviously too vast to consider, but this is the astronomer’s yardstick, the “light year”. Many stars are millions of light years away from us; their light takes millions of years to reach us. We know, from calculation and conjecture, that in fact many stars and constellations which we see each night are simply not there, they vanished, burnt up, thousands, perhaps millions of years ago, but our descendants will be seeing them for a long time yet.

The theory of Copernicus was extended easily to explain the various seasons. The earth went round the sun, rotating as it did to give night and day, but it did so while tilted, and maintaining that tilt, at a little over twenty degrees, constantly pointing at some far-distant point in the universe. Because of this there would be a time in the earth’s annual orbit when the top, northern half would be pointed toward the sun, “leaning” towards it, which would be midsummer in the northern hemisphere. Six months later, when the earth had travelled to the other side of the sun, while remaining tilted in the same direction, it would be the bottom half of the globe which was tilted up towards the sun; it would be midsummer in the southern hemisphere.

Many other theories which had been only dimly considered before the time of Copernicus were suddenly found, on a heliocentric basis, to be perfectly sound. Even in our own century, the work of Albert Einstein, with his theory of Relativity which has opened up a new world of astronomy and physics, has done little to upset the basic theories of Copernicus.

During the wholesale destruction of Warsaw during the Second World War the famous statue of Copernicus was spared by the Germans, but the inscription below: “Nicholas Copernicus; his fellow-countrymen”, was altered to, “Nicholas Copernicus: the German Nation”, on the assumption that the great man could be regarded as a German. (His birthplace, Torun, was a part of East Prussia for many years, but only after his death.)

The inscription was changed back again after the war and Nicholas Copernicus remains one of Poland’s, and the world’s, greatest.