Galileo and the Copernican Theory

The Life of Galileo by Bertolt Brecht, translated by David Hare

Library Theatre Company, 1996

Pythagoras, Aristotle and Ptolemy

Up until the middle of the 16th century, the Earth, to all intents and purposes, lay at the centre of a system of transparent concentric spheres which rolled around each other creating beautiful music.

This deceptively simple picture of the cosmos had mainly derived from the writings of the Greek astronomer Ptolemy (c85–165 AD). His book Almagest had gathered together the principal ideas of the mathematician Pythagoras with an even greater nod towards the philosopher Aristotle, a thinker and polymath so widely respected that his authority on every area of academic study was believed to be absolute.

Each of the planets was attached to its own crystal sphere, he said, and the whole system was enclosed by the largest sphere of all on which were hung the fixed stars. The trouble was, the longer professional astronomers studied the heavens, the more difficult it became to reconcile their observations with the perceived system.

Copernicus, Brahe and Kepler

In 1543 the Polish priest and astronomer Copernicus suggested that these problems largely dissolved if one assumed the centre of the universe – that is, the point from which measurements were taken – was the Sun rather than the Earth. The next significant step was taken by Galileo’s contemporary, the German astronomer Johannes Kepler who, paradoxically in an attempt to bolster up the Ptolomaic system, studied the meticulous records of the astronomical observer Tycho Brahe and came up with three simple rules:

1 – Each planet describes an ellipse of different dimensions but each uses the Sun as one focus.

2 – The planets move at varying speeds but each covers equal areas of its ellipse in equal times.

3 – There is a mathematical connection between the time it takes a planet to orbit the Sun and that planet’s average distance from the Sun.

Even Galileo was reluctant to accept the idea of an ellipse, which in his view was a deformed circle and therefore an imperfect impossibility. But through his new telescope he discovered mountains on the moon, satellites around Jupiter, the phases of Venus, and even sunspots, all of which suggested a much more down-to-earth view of the heavens than accepted wisdom had hitherto allowed. 

Newton, Einstein and…?

It was Isaac Newton, born the year Galileo died, who was to prove that the gravitational force which draws an apple to the Earth is the same as the one which keeps the planets spinning in orbit around the Sun. Heaven and Earth obey the same physical laws, and man is not the centre of the universe after all. And the search for truth goes on. This century Einstein with his Theory of Relativity has inaugurated the next great cycle of observation, discrepancy and adjustment of accepted thought. In the context of the immeasurably large distances throughout the constantly expanding universe and the leap of the imagination needed to investigate particle physics, Galileo now looks as outmoded as Ptolemy and Aristotle.

But so it will continue, for as long as the world turns.

PS

Another of my keenly insightful plummets into the depths of scientific enquiry and the mysteries of the universe. The only reason I ever ended up writing anything scientific was because the others must have ganged up on me and bullied me into it, or I lost the stone, paper, scissors game or something. I have no interest in science and even less in the physical nature of the unknowable infinite. I even read Brecht’s Galileo play Leben des Galilei in the original German at university, and the only insight I came away with was nothing to do with science, merely a resoundingly sad truth about realpolitik: “Unglücklich das Land das keine Helden hat,” yells Galileo’s student Andrea Sarti, disappointed that his master, threatened with torture by the Inquisition, has cravenly retracted his observations confirming the structure of the heliocentric solar system. “Nein, unglücklich das Land das Helden braucht,” Galileo retorts, surely winning the argument. (“Unhappy the land that has no heroes,” “No, unhappy the land that needs heroes.”) It must be over fifty years since I read that. I couldn’t tell you the first thing about Boyle’s Law, but I can still remember that, and who says it, and in the original foreign language.

For some years now my wife has been avid to see the Northern Lights; I couldn’t give a stuff. Is the universe expanding or contracting? Is it, as the cynical academic Bernard Nightingale wonders aloud in Tom Stoppard’s masterpiece Arcadia, “Standing on a stool whistling ‘When Father Painted the Parlour’?” Who knows? Who cares? It literally couldn’t matter less. The first time I sat my physics O-level I failed with 39% (the pass mark was 45%.) The second time I took it I got 33%. I decided to give up while I was behind.

And I have to say my lack of knowledge about how the world wags has not hindered me one iota. As those with a scientific bent might know, an iota is, of course, an imaginary unit number whose value is the square root of minus one. All I know is that it is the ninth letter of the Greek alphabet, equivalent to our word jot, or tiny amount, which in writing may be used to refer to the little horizontal stroke in the letter t. Compare that to the tittle, which is the dot over the lower-case letters i or j. I would rather know that than be able to define the coefficient of linear expansion.

“Unglücklich das Land das keine Physiker hat?” “Nein, unglücklich das Land das Physiker braucht.”