Nicolaus Copernicus

Copernicus’s cosmos

Oh heavens, no

How one man took on the church

Sep 24th 2011 | from the print edition

See the revolution of the times

A More Perfect Heaven: How Copernicus Revolutionised the Cosmos. By Dava Sobel. Walker & Company; 272 pages; $25. Bloomsbury; £14.99 . Buy from Amazon.com, Amazon.co.uk

THE common rule in biography is that the more important the subject, the heavier the tome—with both pages and piety. Dava Sobel flouts this convention. Famous for her delightfully quirky books on the history of science, starting with the 1995 bestseller, “Longitude”, she delivers here a refreshingly fast-paced and breezy account of the life of Nicolaus Copernicus, the Polish cleric who knocked the Earth from its perch at the centre of the solar system and put the sun in its place.

Ever since Claudius Ptolemy published the “Almagest” in the second century AD, almost all astronomers had believed that the Earth lay at the centre of the universe. The sun, the planets and the stars supposedly revolved around it once a day. It was a faith reinforced by common sense, a reverence for the wisdom of antiquity, and its resonance with Christian mythology. Geocentrism fit with several passages in the Bible, and with the church’s view of the world more generally, which held that the Earth, as the abode of God’s greatest creation, sat at the centre of everything. Ptolemy’s model was complex, with planetary orbits modified by smaller orbits (called epicycles), but it fit with observations, and could even be used to predict what the night sky would look like at an arbitrary date in the future.

It is not known when the idea of a sun-centred cosmology came to Copernicus. He was not the first to dream it up: Aristarchus of Samos, a Greek astronomer, proposed something similar around 250BC, although no details of his system survive. Copernicus’s first speculations on the subject appear in a 40-page booklet printed before 1514, which he circulated to some friends and colleagues. Although he continued to refine the theory, he was reluctant to publish, either because he feared ridicule for such an outlandish suggestion, or because he worried about a reaction from the church. Indeed the church would imprison Galileo Galilei, an Italian astronomer, for advocating the sun-centred model of the universe a century later.

But Copernicus did eventually publish his celestial theory at the end of his life. One person seems to have been instrumental in persuading him to go ahead, a scholar called Rheticus, or Georg Joachim von Lauchen, a young mathematician who arrived on Copernicus’s doorstep in 1539 and spent two years as his pupil.

In her introduction, Ms Sobel writes that she has long been fascinated by this meeting. She uses the book to imagine what took place between the two men, presenting it in the form of a play. The scarcity of surviving evidence gives Ms Sobel some poetic latitude. Readers are treated to a demonstration of an arcane machine, subplots involving pederasty and concubinage, and a conspiracy to hide Rheticus’s presence (he was a Lutheran) from the Catholic bishop of Varmia. Rheticus ultimately overcomes his own doubts about Copernicus’s theory and manages to persuade his host to commit his ideas to paper.

“A More Perfect Heaven” does a good job of giving the flavour of life in Reformation-era Europe, at least among its intellectual elite. But there is strangely little discussion of the intellectual underpinnings of Copernicus’s system of the world, and of the meticulous observations that eventually convinced him that Ptolemy was wrong. It was a giant leap suddenly to argue that the Earth orbits the sun, rather than the other way around, particularly without telescopes. Imagine trying to deduce this with the naked eye, a sextant and little else. Then imagine the difficulties of defending it against the obvious criticisms in an era before mathematically rigorous physics: why are we not flung from the Earth if it spins round so fast? Why are there not hurricane-force winds? That Ms Sobel overlooks these questions is a shame, since it rather undervalues an immense intellectual achievement and leaves a noticeable hole in an otherwise excellent book.