The rise of Catholic objections to Copernican ideas

(For those following the Copernican postings in sequence, I made a mistake. Today’s posting should have appeared BEFORE the one that dealt with The role of Protestant opposition to Copernicus. Sorry about that!)

The last myth that I will address concerning the Copernican revolution is that it met immediate, widespread, and religious opposition from the Catholic Church. This took the form of releasing the full force of the Inquisition against his ideas, which resulted in Copernican Giordano Bruno being burned for advocating those ideas and Galileo being forced to recant his support for Copernicus’ sun-centered universe. This is the view, for example, expressed by Bertholt Brecht in his famous play Life of Galileo.

Religious opposition did eventually arise but not immediately and the initiative came from the newly formed Protestant churches, not the Catholic Church.

One reason that there was no immediate religious opposition to Copernicus’ book De Revolutionibus Orbium Caelestium was because his book was very mathematical and hence incomprehensible to anyone other than other mathematical astronomers. And we saw that this small group had good reason to be skeptical, on scientific rather than religious grounds, of the idea that the Earth was in motion.

Another possible reason for the lack of religious opposition was that putting the Earth in orbit around the Sun was not perceived at that time as a demotion for human beings, as is now portrayed.

A third possible reason was that the Catholic Church did not find this new idea as heretical as is now supposed. It is worthwhile to quote Thomas Kuhn’s book The Copernican Revolution more fully on this point:

For sixty years after Copernicus’ death [in 1543] …individual Catholic clergymen expressed their incredulity or abhorrence of the new conception of the earth, but the Church itself was silent. The De Revolutionibus was read and at least partially taught at leading Catholic universities. Reinhold’s Prutenic Tables, based on Copernicus’ mathematical system, were used in the reformation of the calendar promulgated for the Catholic world in 1582 by Gregory XIII. Copernicus himself had been a cleric and a reputable one, whose judgment was widely sought on astronomical and other matters. His book was dedicated to the Pope, and among the friends who urged him to publish it were a Catholic bishop and a cardinal. During the fourteenth, fifteenth, and sixteenth centuries the Church had not imposed cosmological conformity on its members. The De Revolutionibus was itself a product of the latitude allowed to Churchmen in matters of science and philosophy, and before the De Revolutionibus the Church had spawned even more revolutionary cosmological concepts without theological convulsions. In the fifteenth century the eminent cardinal and papal legate Nicholas of Cusa had propounded a radical Neoplatonic cosmology and had not even bothered about the conflict between his views and scripture. Though he portrayed the earth as a moving star, like the sun and other stars, and though his works were widely read and had great influence, he was not condemned or even criticized by his church. (p. 196)

And yet it is true that, beginning in 1616, the Church banned teaching of the idea of a sun-centered universe and De Revolutionibus was placed on The Catholic Index of forbidden book in 1616 (and stayed there until 1835). This period also began the dismissal and banishment of prominent Catholic Copernicans, culminating in the forced recantation of Copernicus’s ideas in 1633 by Galileo (then nearly 70 years old) under threat of torture by the Inquisition, and his subsequent house arrest. The Church ban on Copernican ideas remained until 1822 and has been a source of embarrassment for the Church ever since.

(In 1600 the Church burned the philosopher Giordano Bruno (who was a Copernican) at the stake for heresy, but it was not explicitly for that particular belief. He had committed other heresies involving the doctrine of the Trinity for which other people had also been executed earlier. Bruno had been an advocate and popularizer of Copernican ideas, though, which might have led to the popular perception that he was the first martyr for the new science.)

But by 1633 it was too late for the Church to stop Copernican ideas because by then new supporting evidence for it was arriving thick and fast. They were trying to stop the tide when it was in full flood, and the attempt was a hopeless failure.

Tycho Brahe (1546-1601), although a believer in an Earth-centered universe, had by then produced accurate naked eye observations of stars which had removed many false old data that had confused the picture and provided a whole set of new data that planetary models needed to fit.

Johannes Kepler (1571-1630) was a life-long Copernican who devoted himself to address the problems of the sun-centered model and his eventual adoption of elliptical orbits led to the elimination of the awkward epicycles in Copernicus’ model. His three laws of planetary motion were a triumph of simplicity in explaining planetary motion and his Rudolphine Tables, published in 1627, was so superior to all other astronomical tables that they became widely used and their underlying Copernican basis was becoming widely known and appreciated. “Kepler solved the problem of the planets.” (p. 219)

And the final nail in the earth-centered cosmology was Galileo’s use of the telescope for astronomy, beginning in 1610. These telescopes were soon freely available and suddenly everyone could observe the stars and planets and see for themselves what had hitherto been just the province of astronomers. Among other things, Galileo’s discovery of the moons of Jupiter was a devastating blow to the Ptolemaic model since it showed that not everything was orbiting around the Earth, as was the key assumption of the geocentric models.

Finally, Isaac Newton’s (1643-1727) dynamical theories of motion and gravitation that explained Kepler’s laws were the sign that the Copernican revolution, begun about 150 years earlier, was complete.

But although the Church lost this battle a long time ago, it took over three centuries for it to formally acknowledge this. It was only in 1992 that Pope John Paul II lifted its edict of Inquisition against Galileo. The Pope even went so far as to claim that Galileo may have been divinely inspired, saying: “Galileo sensed in his scientific research the presence of the Creator who, stirring in the depths of his spirit, stimulated him, anticipating and assisting his intuitions.” This may have been a rather futile effort to recover some dignity from an embarrassing debacle for religion.

But what happened between 1543 and 1610 to cause the Catholic Church to switch from neutrality to opposition, and adopt such a hard-line, long-lasting, and ultimately futile anti-Copernican stand? We’ll see that in a future post. (Update: Due to the mis-sequencing, this ‘future’ posting already appeared three days ago as The role of Protestant opposition to Copernicus.)

Having fun with telephone representatives

Once in a while, I look in on the site Jesus’ General which is a parody website that is hard to describe but is often hilarious. It was the most recent winner of the Koufax Award for Most Humorous Blog.

Recently, the General posted an item about a telephone conversation that someone named Eugene Mirman had with a representative who was trying to get him to switch to her Christian long-distance phone company. As part of her sales pitch to Mirman, the phone rep first made sure that Mirman was opposed to same-sex marriages and then proceeded to allege that rival phone companies AT&T, MCI, and Verizon were all involved in promoting hard-core pornography, child pornography, and homosexuality, thus making them unworthy of God-fearing people.

The recording has Mirman becoming increasingly scandalized by the revelations he hears about these companies. The telemarketer seems oblivious to the fact that he is putting her on. His over-the-top outrage at the sins of AT&T, MCI, and Verizon, which seemed to me to be such an obvious leg-pull, seemed to appear genuine to the phone rep, which makes me wonder if they routinely get calls from people who actually think and talk like that.

Such pranks as the one Mirman pulled usually give me mixed feelings. On the one hand, the people who answer the phones are usually low-paid employees, reading from a script provided by their employers and may not be true believers themselves. They are often just doing what they are told, and I feel a bit sorry for them. I try to be polite to them (even to telemarketers), even while I am annoyed at the companies they represent. (It is interesting that this particular company’s website does not have any overt religious or anti-gay message so that aspect of its business must be done through other channels that pre-screen to contact those people already sympathetic to their views.)

On the other hand, using pretty wild religious messages (at one point she agrees with Merman that “God hates AT&T, MCI, and Verizon”) and vicious anti-gay rhetoric as a sales tool struck me as particularly despicable and so I had no qualms laughing out loud as I listened to Merman’s ranting. It was also amusing to hear the efforts by the phone rep to keep him angry but not enough to prevent him from seeing the main point, which was to switch his phone service provider to her company.

Listen to the mp3 audio clips yourself, especially the link to “Anti Gay Phone Company II.” It’s a riot.

The reading level of this blog

I came across an interesting website recently. You type in the URL of any site and it comes back immediately with various measures of the site’s readability, including the years of education necessary to understand it, its clarity, and so forth. It also provides comparisons on these indices with various standard media such as newspapers and magazines.

So naturally the first thing that I did was put in this blog’s URL to see how I shaped up. Here is what I got:

Readability Results for http://blog.case.edu/mxs24
Average words per sentence 16.15
Words with 1 Syllable 3,230
Words with 2 Syllables 1,010
Words with 3 Syllables 561
Words with 4 or more Syllables 415
Percentage of word with three or more syllables 18.71%
Average Syllables per Word 1.65

That much was pretty straightforward. The other three numbers were more mysterious:
Gunning Fog Index 13.94
Flesch Reading Ease 51.07
Flesch-Kincaid Grade 10.15

The site helpfully explains that the Fog Index “is a rough measure of how many years of schooling it would take someone to understand the content. The lower the number, the more understandable the content will be to your visitors. Results over seventeen are reported as seventeen, where seventeen is considered post-graduate level.” Looking at the algorithm, it seems to depend entirely on the number of words per sentence and the percentage of words that have three or more syllables.

So it takes about 14 years of education (or up to college sophomore level) for someone to understand the content of my website. So clearly I am not going to get huge market share with my blog.

For comparison, some Fog Index Scores are given for other publications:

6 TV guides, The Bible, Mark Twain
8 Reader’s Digest
8 – 10 Most popular novels
10 Time, Newsweek
11 Wall Street Journal
14 The Times, The Guardian
15 – 20 Academic papers
Over 20 Only government sites can get away with this, because you can’t ignore them.
Over 30 The government is covering something up

Since my Fog Index score is close to 15, it seems like it is hard for me to shake the habits of writing in the style of academic papers even in the more casual setting of a blog.

The Flesch Reading Ease number “rates the text on a 100-point scale. The higher the score, the easier it is to understand the document. Authors are encouraged to aim for a score of approximately 60 to 70.” So I flunk this score pretty badly, it looks like. This algorithm, seems to depend entirely on the number of words per sentence and the average number of syllables per word.

The Flesch-Kincaid grade level, like the Gunning-Fog index, “is a rough measure of how many years of schooling it would take someone to understand the content. Negative results are reported as zero, and numbers over twelve are reported as twelve.” This seems like the same measure as the Fog Index, but uses average number of syllables per word instead on percentage of words with three syllables or more.

What is one to make of things like this? I find them fun even if I don’t take them too seriously. For one thing, you have to be skeptical of these instant computer-generated analyses of such complex things as writing. While these programs are great at doing numbers, one has to be wary of claims that they can accurately measure things like clarity and reading grade level. They all assume that the number of polysyllabic words and the length of sentences are the only factors, and that the nature of the content is immaterial.

This explains the results for the Bible, which had initially puzzled me. It is ranked together with TV Guide, although surely it is a more difficult book to understand. But it does use short words and sentences. This kind of algorithm also also might explain why the Wall Street Journal, which one might think is less readable than the New York Times, scores at three grades below it.

Suppose I want to become more easily readable. Should I use more words of one syllable? Or shorter sentences? Or both? Or is it the topics that cause the problem? When you write about academic topics, polysyllabic words (two already in this sentence!) creep in without any effort. Can I write about the Copernican Revolution (two more!) and avoid words like heliocentric (another one!)

To become more readable must I switch my focus from history and philosophy of science to Britney Spears? There are some prices that are too high to pay even for increased ease of readability…

The role of Protestant opposition to Copernicus

For many years after the publication of Copernicus’ book De Revolutionibus Orbium Caelestium in 1543, his ideas remained within the mathematical astronomy community. The more popular books on astronomy and cosmology either were unaware of his work or chose to ignore them. But there were a few non-astronomers such as poets who were aware of his work and they ridiculed it for advocating a moving Earth, not because of any ideas of heresy. It was though the poets and other popularizing writers of that time that Copernicus’ ideas became more widely known.

It is interesting that the earliest objections to Copernican ideas on religious grounds came from Protestant groups, who are usually missing in the popular folk history which features the dispute as being between Copernicus and the Catholic Church. Thomas Kuhn in his book The Copernican Revolution suggests that this was because the people of the Reformation (led by Martin Luther in his break with the Catholic Church) were emphasizing Biblical authority, viewing “the Bible as the single fundamental source of Christian knowledge” as opposed to the Catholic Church which focused more on doctrinal issues that allowed it more flexibility in dealing with science. And there were clear contradictions between the Bible and Copernicus.

Martin Luther spoke out against Copernican ideas in 1539 saying that the idea of a moving Earth going around a stationary Sun clearly went against the book of Joshua [10:13] that said that Joshua commanded the Sun to stand still. Luther’s main lieutenant Melanchthon followed up by finding other Biblical versus that suggested that the Earth was stationary. This was followed up by other Protestant leaders such as Calvin (Kuhn 191-193).

Pretty soon the Bible became the main weapon used against Copernican ideas and clergymen in the seventeenth century started going through the Bible line by line, looking for arguments.

The conflicts between the Bible and Copernicanism did not stop just with verses that dealt with the Earth’s motion. Recall that acceptance of Copernicanism implied acceptance of a whole range of associated physics ideas and these raised profound theological issues. As Kuhn points out (p. 193):

When it was taken seriously, Copernicus’ proposal raised many gigantic problems for the believing Christian. If, for example, the earth were merely one of six planets, how were the stories of the Fall and of the Salvation, with their immense bearing on Christian life, to be preserved? If there were other bodies essentially like the earth, God’s goodness would surely necessitate that they, too, be inhabited. But if there were men on other planets, how could they be descendents of Adam and Eve, and how could they have inherited the original sin, which explains man’s otherwise incomprehensible travail on an earth made for him by a good and omnipotent deity? Again, how could men on other planets know of the Savior who opened to them the possibility of eternal life? Or, if the earth is a planet and therefore a celestial body located away from the center of the universe, what becomes of man’s intermediate but focal position between the devils and the angels? If the earth, as a planet, participates in the nature of celestial bodies, it cannot be a sink of iniquity from which man will long to escape to the divine purity of the heavens. Nor can the heavens be a suitable abode for God if they participate in the evils and imperfections so clearly visible on a planetary earth. Worst of all, if the universe is infinite, as many of the later Copernicans thought, where can God’s Throne be located? In an infinite universe, how is man to find God or God man?

It was clear that Copernicus’s ideas were seriously discomfiting for Christians, especially the Biblical literalists that were dominant in the new Protestant movement, which provided the first institutionalized opposition. People started calling the Copernicans ‘infidels’ and ‘atheists’ and urging their repression. But the Protestant churches did not have the powers of enforcement that the Catholics had.

Kuhn argues that it was probably due to the pressure from the burgeoning Protestant church that caused the Catholic Church in 1616 to abruptly switch its policy from tolerance of Copernican ideas to repression. “Copernican doctrines were, in fact, condemned during the Counter Reformation, just when the Church was most convulsed by internal reforms designed to meet Protestant criticism. Anti-Copernicanism seems, at least in part, one of these reforms, Another cause of the Church’s increased sensitivity to Copernicanism after 1610 may well have been a delayed awakening to the fuller theological implications of the earth’s motions. In the sixteenth century those implications had rarely been made explicit.” (p. 198)

In an earlier posting we showed that the idea of a moving Earth being considered a demotion for human beings is something that arose only in the late 17th century. It may be that this idea was developed from around 1650 onwards when religious bodies were fighting what was essentially a propaganda war against heliocentric ideas, the scientific battle being essentially already lost. It may have served as part of the effort to rally non-scientific (but religious) people to turn against Copernican ideas by appealing to their pride.

What is ironic is that after being the possible impetus for the Catholic Church turning against Copernicanism, the Protestant churches fairly quickly abandoned their opposition to these ideas when it became clear that the evidence in favor of a Sun-centered system was overwhelming. But the Catholic Church, being a much larger and more tradition-bound and bureaucratic operation, was left clinging to its anti-Copernican views for a long time afterwards. The Church ban on Copernican ideas remained until 1822 and his book remained on the list of forbidden books until 1835. In fact it was only as recently as 1992 that Pope John Paul II lifted its edict of Inquisition against Galileo. Thus the Catholic Church is now the religious institution identified with perhaps the most notorious anti-science episode in history.

This ends the series of postings on the myths surrounding the Copernican revolution. Another interesting feature about the whole Copernican story is the parallel with Darwinian evolution and the opposition to it, right up to the present so-called intelligent design movement. These questions will be examined in a later posting.

The myth concerning circular orbits

In this posting we will examine the myth that the Copernican revolution was hampered by its insistence that the orbits be circles.

To understand the reasons behind this we need to look at the work of an influential, but often unrecognized, player in the Copernican revolution, the astronomer Tycho Brahe (1546-1601). He is considered the greatest naked-eye astronomer. He lived just before the invention of telescopes and the accuracy, scope, and reliability of his observations had enormous impact on the field.

It is interesting that Brahe, like most astronomers at that time, rejected Copernicus’ ideas of a moving Earth. He could not accept the arguments for the Earth’s motion, seeing that as creating more problems than solving them. In fact, he developed his own system (called the Tychonic system) that was mathematically equivalent to the Copernican system, but had the Earth as a stationary center. (p. 202. Most of the material in this post is from Thomas Kuhn’s book The Copernican Revolution and page numbers are from that book.)

But despite his opposition to a heliocentric system, his data provided two major benefits for the Copernican model. They got rid of some erroneous old data that plagued all the earlier models because they were so hard to fit within any mathematical framework. That helped to remove some of the anomalies that the Copernican system could not explain. And they generated new precise data that provided the kinds of puzzles that enabled Copernican convert Johannes Kepler (1571-1630) to come up with the idea that the motions of the planets were not based on circular motion (as Copernicus and Ptolemy and Brahe had all assumed) but elliptical.

In the folk history that surrounds the Copernican revolution, the introduction of elliptical orbits is rightly recognized as a crucial development that helped in its eventual acceptance, but the pre-Keplerian astronomers are wrongly criticized for insisting on circular motion. It is implied that they did this because of aesthetic considerations and because of slavish adherence to the authority of the Greek philosophers and so forth. We quoted in a previous post the introductory physics textbook Physics by Fishbane, Gasiorowicz, and Thornton which gently chided Copernicus for his seemingly rigid and dogmatic adherence to some aspects of orthodoxy. “Unfortunately, Copernicus continued to insist on describing all motions with circles and, because the true motions of the planets about the Sun are not circles, epicycles continued to be needed in the Copernican description to accommodate the observations of planetary motion.” (p. 320, emphasis added.)

This is an unfair characterization.

The reasons for assuming circular motions were quite reasonable, when seen through the eyes of the people at that time. Since there was no notion of force or gravity then, you needed to have an explanation of motion. As the motions of the stars and planets were regularly repeating, it was not unreasonable to assume they had the simplest repeating motion, which was that of an object going around in a circle. In the case of circular motion the dynamical questions could also be finessed away by saying that the object could be considered as “doing the same thing” or “moving in the same way” all the time or with no variation in its motion. This made it easier to think of this kind of motion as ‘natural’ in some way, that once it had been set in motion it would continue, and did not require any further explanation. (p. 245)

If you had more complicated motions like ellipses and the like, that would have meant that the speeds and positions of the planets were constantly changing and this required a dynamical theory of motion that simply did not exist at that time. Recall that just introducing the idea of a moving Earth created all kinds of new unsolved problems for the existing physical theories of that time. Adding non-circular motions would have compounded those problems even further and provided even greater grounds for rejection of Copernican ideas.

So it was eminently sensible of Copernicus to stick with circular motions (assuming that he had even considered alternatives) and we should refrain from imposing harsh retrospective judgments on the people involved simply because we have the benefit of hindsight. Copernicus had to work with what he had.

Kepler’s innovative idea of elliptical orbits enabled the Copernican model to dispense with the cumbersome and complicated epicycles. But in order to justify this non-circular motion and make it more worthy of acceptance, Kepler had to introduce his own theories of motion, which included an inverse-square law and an anima motrix (p. 214). These innovations led to Kepler’s laws of planetary motion, which led in turn later to Newton’s successful theories of motion and gravitation.

If all these matters had been left only to astronomers, Copernicus’ ideas would probably have achieved a quiet victory. But that was not to be. As the significance of his ideas reached beyond the community of mathematical astronomers, a religious reaction ensued, and it is this that we will examine in a future posting. The nature of this religious reaction has some surprising features that run counter to the folk history surrounding the Copernican revolution, and has interesting parallels with the current efforts to oppose evolution.

Those things will be explored in future postings.

Copernicus’ ideas gain support from a few astronomers

As astronomical observations became more comprehensive, and as sea-faring became more widespread, the need for better star-charts in order to have more accurate time-keeping and navigation became imperative. In order to meet this demand for increased accuracy, the method of epicycles outlined by Ptolemy became more and more complicated, and was extended in different ways by different mathematical astronomers until it became hard to say what the Ptolemaic system was. Instead there were a whole set of different calculations all based on the Ptolemaic system, all getting increasingly complicated. And none of them quite agreed with the full range of good naked-eye observations. (p. 139. Most of the material in this post is from Thomas Kuhn’s book The Copernican Revolution and page numbers are from that book.)

Part of the problem was that some of the earlier observations were simply erroneous, a problem that plagued Ptolemaic and Copernican astronomy alike, and these went away later as better observations came along (p. 139). But other problems were more substantive.

This state of affairs was unsatisfactory to say the least. But while many astronomers felt that the Ptolemaic system, although complicated, could ultimately be made to work with further tinkering, Copernicus felt that this was a sign that the two-sphere model itself was at fault and needed to be replaced, and thus proposed his new model.

But because his system, like that of Ptolemy, used circles for the orbits, it also needed epicycles to give more detailed predictions. And as the observational data got better, it too started getting very complicated.

As Kuhn says:

His full system was little if any less cumbersome than Ptolemy’s had been. Both employed over thirty circles; there was little to choose between them in economy. Nor could the two systems be distinguished by their accuracy. When Copernicus had finished adding circles, his cumbersome sun-centered system gave results as accurate as Ptolemy’s, but did not give more accurate results. Copernicus had failed to solve the problem of the planets. (p. 169)

The Copernican model had some aesthetic and qualitative advantages over the Ptolemaic system. It provided a more natural qualitative explanation for the retrograde (zig-zag) motion of planets like Mars as observed from the Earth and answered some important questions concerning the ordering of the planets. Kuhn continues:

Judged on purely practical grounds, Copernicus’s new planetary system was a failure; it was neither more accurate nor significantly simpler than its Ptolemaic predecessors. But historically the new system was a great success; the De Revolutionibus did convince a few of Copernicus’ successors that sun-centered astronomy held the key to the problem of the planets, and these men finally provided the simple and accurate solution that Copernicus had sought. (p. 171)

This is an important point to appreciate about scientific revolutions. They very rarely give demonstrably better results than their predecessors right at the start. What usually happens is that they have an appeal (often aesthetic) that attracts others to work within the new model and solve the puzzles and problems generated by it. And if the new model proves fruitful over time in solving more puzzles, then it gains adherents.

It is important to understand that Copernicus’ work initially was restricted to the community of astronomers. Copernicus was widely respected as one of Europe’s leading astronomers and reports about his work, including his heliocentric hypothesis had been circulating since 1515, so when his De Revolutionibus was published in 1543, it was hardly a surprise to other astronomers. But even those who were skeptical of the idea of a moving Earth accepted that it was the most comprehensive account of celestial motions since Ptolemy.

But while astronomers hailed his work and used his tables and methods, most were skeptical of the central idea of a moving Earth. They dismissed it as some kind of artificial trick that turned out to be useful in providing calculations for the motion of planets (similar to the way that Planck’s quantum hypothesis was initially conceived). This idea that the motion described by a model was a convenient fiction was not unprecedented. Ptolemy himself had said that not all of his own epicycles had to be considered physically real. Some were to be thought of as mathematical fictions that gave numerically sound results (p. 186).

But the very fact that the Copernican model was useful attracted new people to study it and thus its ideas spread within the astronomical community, and its central thesis did gain a few converts, although they were a small minority. One of the key converts was Johannes Kepler, who (as we shall see later) was to play a key role in removing the epicycles from Copernicus’ model and sealing its superiority.

Copernicus and the laws of physics

In a previous post, we saw that the popular notion that the Copernican model of the universe was opposed because it implied a demotion for human beings is not supported by close examination of the views of the people actually living in those times. It is, instead, a revisionist version of events that gained ascendancy around 1700 or so.

In today’s post we will examine the myth that the immediate opposition to Copernicus was raised by religious people. The fact that the Copernican model was not perceived contemporaneously as a demotion already weakens the case for that story but there’s more.

To understand this better, we need to understand the broader framework of physics in which astronomy was embedded. This framework was due to Aristotle. He did not invent it completely but incorporated many of the ideas that were around at that time into a comprehensive system that encompassed physics and astronomy. (Most of the material in this post is from Thomas Kuhn’s book The Copernican Revolution and page numbers are from that book.)

In Aristotle’s cosmology, the universe was composed of a series of rotating concentric spheres, with the stars embedded in the outermost sphere and the planets embedded in inner spheres. The Earth was a small sphere located at the center of this universe. The universe was finite and the heavens existed beyond the outermost sphere. In this cosmology, the directions ‘up’ and ‘down’ were well-defined. ‘Down’ was towards the center of the universe and ‘up’ was away from it, towards the sphere containing the stars.

The elements were earth, air, water, and fire and each element had its natural affinity for a location in this universe. As could be seen from the fact that rocks fell to the ground, earth (being heavy) was drawn to the center. On the other hand, the fact that flames leaped upwards showed that fire (being light) was drawn towards the heavens. Aristotle was pretty clear that he was saying that the Earth was at the center of the universe, not because it was important, but simply because it was massive. To quote Aristotle “It so happens that the earth and the Universe have the same center, for the heavenly bodies do move towards the center of the earth, yet only incidentally, because it has as its center at the center of the universe.” (p. 84)

This model explained lots of things such as why objects fell to the ground when released from any point on the Earth’s surface (it was being attracted to the center of the universe) and why the Earth was spherical in shape. But it also explained why the Earth was motionless at the center. For it to move, then there had to be some constraint that took it away from the center, just as it required someone to lift an object in order to raise it above the ground. (The concept of ‘force’ had not yet been introduced.)

This model of the universe was successful in explaining the motions of the stars, but that was only a small part of the reasons for its acceptance. There were alternate models of the universe that postulated a moving and rotating Earth but, as Kuhn points out, there were excellent reasons for accepting Aristotelian physics and its resulting cosmology over its competitors. It simply made a lot more sense.

For example, Copernicus’ heliocentric model required the Earth to be in motion. But what constraint caused it to move away from the center? Nobody could explain that. Furthermore, if the Earth was not stationary at the center, but was midway in the sequence of planetary orbits around the Sun, then how could you define ‘up’ and ‘down’? Why would objects fall ‘down’ if the Earth were not at the center of the universe (remember that the concept of gravitational mass had not been invented then)? Nobody could explain that either. How could objects that were thrown vertically upwards fall back to the same point if the Earth were not at rest? Another unexplained puzzle.

And since the Earth was still believed to be the most massive object in the universe, then if it was not drawn to a fixed point at the center of the universe, did that mean that there was no center at all? If there was no center to that universe, could that mean that the universe was infinite?

So accepting Copernicus’s ideas was to not simply replace one model for the stars and planets with another. It also meant that a whole class of physics problems that had been considered solved were suddenly unsolved.

The reason that Copernicus’ ideas ran into opposition, at least in its immediate aftermath was not because of the supposed demotion of humans, but because having a heliocentric system resulted in the creation of a lot of problems for the physical theories that were coexisting with the astronomical models. So much of the initial resistance was from within the physics and astronomy communities, not the religious ones.

In fact, Copernicus did not seem to fear religious opposition to his ideas. In his landmark book De Revolutionibus Orbium Caelestium he even had a prefatory letter addressed to Pope Paul III where he apologized for the seeming outlandishness of his suggestion that the Earth moved but explained that he was forced to arrive at that hypothesis because of the inadequacy of the Ptolemaic system in predicting the positions of stars or its adequacy for constructing calendars.

Copernicus’ ideas stayed within the science and astronomy community for a long time, even though he was not hiding them. But only they were interested in the improvements to the calculations that he promised. And it was from among them that initial opposition existed, not from the religious sector.

Now, thanks to years of education, we reject the idea of a geocentric universe, but Kuhn points out that even now children and primitive peoples still have Aristotelian ideas. And recent research in physics education reveals that Aristotelian physics concepts are still retained by many people despite years of formal education to the contrary. This is because the ideas make so much intuitive sense. So it was perfectly reasonable and rational for this cosmology to be preferred over its competitors and for Copernicus’ ideas to meet opposition.

This point will be elaborated in later postings.

Was the Copernican model a demotion for human beings?

In this post, we will look at one particular myth surrounding the Copernican story, the one that says that Copernican ideas were opposed because they implied a demotion for human beings.

Nicolaus Copernicus (1473-1543) published De Revolutionibus Orbium Caelestium, his epic work describing a heliocentric system, in 1543 the year of his death. Until then, Ptolemy’s geocentric model described in his Almagest had been the one used for studying planetary motions. In this model, the Earth was at the center of the universe and every celestial body orbited about the center. The Almagest was the “first systematic mathematical treatise to give a complete, detailed, and quantitative account of all the celestial motions.” (Thomas Kuhn, The Copernican Revolution, p. 72) This work was so good and its methods so powerful, that it provided the framework for astronomical calculations for nearly 1500 years. It was the framework that guided Copernicus’ own work.

One of the key elements of the folklore surrounding the Copernican revolution is that the idea of a heliocentric system was opposed because it dethroned the Earth from its privileged central position as the center of the universe. It is believed that religious authorities (mainly the Roman Catholic Church) wanted to retain the geocentric model because human beings were God’s special creation and since they lived on the Earth it seemed only right that the Earth should be at the center of the universe. So Copernican ideas were opposed because they seemed to imply a demotion for humans and were thus a blow to human pride.

This view of history can be found in the statements of eminent people such as geneticist Theodosius Dobzhansky who in 1973 (on the occasion of the 500th anniversary of Copernicus’ birth) wrote that with Copernicus, the Earth “was dethroned from its presumed centrality and preeminence.” Carl Sagan described Copernicanism as the first of a series of “Great Demotions…delivered to human pride.” Britain’s Astronomer Royal Sir Martin Rees said “It is over 400 years since Copernicus dethroned the Earth from the privileged position that Ptolemy’s cosmology accorded it.” Sigmund Freud said that Copernicus caused an outrage against humankind’s “naïve self-love.” Biological anthropologist Terrence Deacon said that: “Since Copernicus first suggested that Terra Firma might not be located at the center of the cosmos, most of the remaining vestiges of human specialness have come into doubt.”

Dennis R. Danielson in his article The Great Copernican Cliché (American Journal of Physics, vol. 69, October 2001, p. 1029-1035) tries to sweep away this particular aspect of the Copernican folklore. (The above quotes are from that article.)

The first point that Danielson makes is that the Earth was not believed (even by Aristotle) to be the center of the universe, it was thought to be at the center of the universe, and the distinction is important. It was believed that there was a center of the universe (defined as the center of the large outer sphere in which the stars were embedded) and that matter was drawn to that center. This was why the Earth, being the most massive body (the other elements being water, air, and fire) ended up motionless at the center. There was nothing anthropomorphic in this idea. It was quite physical and naturalistic.

Danielson further points out that the center of the universe was not considered, at that time, a desirable place to be. “In most medieval interpretations of Aristotle’s and Ptolemy’s cosmology, earth’s position at the center of the universe was taken as evidence not of its importance but (to use a term still in circulation) its grossness.”

In fact, it was believed by ancient and medieval Arabic, Jewish, and Christian thought that the center was the worst part of the universe, the basement, the sump, where all the muck was collected, so being at the center was not worn as a badge of pride. Danielson points out that in Dante Alighieri’s (1265-1321) Divine Comedy, hell itself is in the inner core of the Earth, which is close to the very center of the universe, consistent with it being considered a foul place. Dante also speaks of hell in ways consistent with Aristotelian dynamics, not as full of flames (because fire is up in the sky, displaced by the heavier earth) but as frozen and immobile.

Danielson quotes medieval writers describing the location of the Earth as “the excrementary and filthy parts of the lower world” and that we humans are “lodged here in the dirt and filth of the world, nailed and riveted to the worst and deadest part of the universe, in the lowest story of the house, and most remote from the heavenly arch.” Cardinal Bellarmine in 1615 says “the earth is very far from heaven and sits motionless at the center of the world”, again emphasizing the low status of the center, since the center is very far from heaven.

By contrast, heaven was ‘up’ and the further up you went in the sky, away from the center, the better it was. So what Copernicus was suggesting, by putting the Sun at the center and the Earth in orbit around it was really a promotion for the Earth and its inhabitants, taking them closer to the heavens.

So when did this history get inverted so that now we believe the opposite? Danielson is unable to pinpoint when exactly the present erroneous view that it was a demotion gained supremacy but he says that from 1650 onwards you can find some writers making that claim and that by the time you get to writer, scientist, and philosopher Goethe (1749-1832) the new belief had taken hold completely. Goethe himself wrote:

Perhaps no discovery or opinion ever produced a greater effect on the human spirit than did the teaching of Copernicus. No sooner was the earth recognized as being round and self-contained, than it was obliged to relinquish the colossal privilege of being the center of the world.

We see that Goethe manages to propagate two historical distortions in that one small paragraph, first repeating the notion of the Earth being found to be round only around the time of Copernicus (and which we refuted earlier in the posting about Columbus), and then that the Copernican revolution was a demotion for humans.

So why and how did this revisionist view of history gain supremacy? It is hard to tell but Danielson suggests some reasons. One is that after the heliocentric model had been well established, the location of the Sun did come to be perceived as a special and privileged place, since all the planets revolved around it, and the Earth was simply one of many planets. So people read back into history the newly believed excellence of the center and imposed that belief retrospectively on the pre-Copernicans.

Another possibility is that the story of humankind’s demotion became a form of perverse pride for human beings. As Danielson says:

[T]he trick of this supposed dethronement is that, while purportedly rendering “Man” less cosmically and metaphysically important, it actually enthrones us modern “scientific humans” in all our enlightened superiority. It declares in effect, “We’re truly very special because we’ve shown that we’re not so special.” (emphasis in original)

But if, in reality, at the time of Copernicus and for some time after, the heliocentric model was seen as a promotion for humans and not a demotion, why was the model opposed? When exactly did the opposition arise? And by whom? In future posts we will look at these and other elements of the Copernican folklore and see what turns up.

Looking closely at scientific history

Since I started looking more closely into the history of science, there are two things that I have learned that I have recast into principles.

The first is that the more closely we examine important historical events in science, the less resemblance they bear to the popular condensed capsule versions that are learned in school or college or portrayed in the popular media. The earlier posting about Columbus and the flat Earth is a case in point.

The second principle is that while science textbooks are usually good for teaching the current principles of science, they tend to be bad for teaching anything about the history of science or the nature of science. In those cases, what they usually describe is better described as folklore rather than history.

Take for example one of the most famous of all scientific revolutions, the one associated with Copernicus. The popular version of this story goes as follows:

The ancient Greeks, while pretty good at mapping the stars and motion of planets, tended to create models of the universe that were strongly influenced by religious, philosophical, and aesthetic considerations, rather than on observation and experiment. Hence they came up with the idea that the Earth was the stationary center of the universe (which pleased those religious people who wanted to give pride of place to the home of God’s greatest creation – human beings) and that the stars and planets were embedded on the surface of a sphere that rotated around the Earth in circles, which pleased those philosophers with highly refined sensibilities who felt that since the circle and sphere were the most perfect geometric shapes, they had to play a central role in the cosmos.

The story continues that the prestige of these ancient Greek philosophers such as Aristotle (384-322 BCE) was so great, and commitment to religious doctrine so strong, that many people gave blind adherence to these ideas and stubbornly tried to retain them in the face of contrary evidence. For example, the planet Mars usually moves in the eastward direction in the sky but sometimes shows retrograde motion (i.e., zig-zags, briefly heading westward before going eastward again). To explain this and other peculiar behavior epicycles were incorporated were incorporated into the Earth-centered circular orbits.

To visualize how an epicycle works, imagine a child on a merry-go-round who, while being carried around in a big circle (called the deferent) by the merry-go-round, is herself running around one of the horses in a smaller circle (the epicycle). When viewed from the stationary center of the merry-go-round, her resulting motion is quite complicated, and sometimes she will appear to be moving in the direction opposite to the merry-go-round itself. This model was used to explain retrograde motion of Mars when viewed from the Earth.

But while this helped, it did not explain all the features of planetary motion and this required adding even more complicated epicyclic motion, culminating in the comprehensive mathematical system developed by Ptolemy (100-178 CE), and written up in his Almagest, which became the standard model.

When Nicolaus Copernicus came along with his model of a Sun-centered system, his ideas were fiercely opposed by the Roman Catholic Church because they displaced the Earth from the center of the system and this was seen as a demotion for human beings and counter to the teachings of Aristotle. This resulted in the inquisitors of the Spanish Inquisition persecuting, torturing, and killing for heresy those people who advocated Copernican ideas, although popular history is hazy on what exactly was done to which scientist. Galileo Galilei is thought to have been most affected by the Inquisition. It was Isaac Newton’s monumental work on motion and gravity that finally sealed the acceptance of Copernican ideas.

The above version of the Copernican story, that blind adherence to the doctrines of great philosophers like Aristotle, supported by religious dogmas, hampered the development of science, is what is popularly believed and passed on in science textbooks, which usually provide a breezy and quick synopsis of the above scientific history, with minor variations.

For example, take the introductory physics textbook Physics by Fishbane, Gasiorowicz, and Thornton. It is a very good textbook as far as the physics goes (I used it when I taught the introductory physics courses) but says things like “Blind reverence for authority impedes scientific progress, and for a long period the work of ancient Greeks was regarded with crippling irreverence.” (p. 1) and “[Ptolemy's] theory was limited by a culturally imposed belief that perfect, circular motion describes celestial motion.” (p. 321) Even Copernicus is gently chided for his rigid adherence to some aspects of orthodoxy. “Unfortunately, Copernicus continued to insist on describing all motions with circles and, because the true motions of the planets about the Sun are not circles, epicycles continued to be needed in the Copernican description to accommodate the observations of planetary motion.” (p. 320)

The Greek philosophers are often spoken of (at least in physics circles) as being great philosophers but rotten scientists. One gets the strong feeling, in reading such accounts, that because of the dogma imposed on people by the ancient Greeks and the Church, scientific progress was held back for a thousand years or so.

So that, I assert, is what people generally believe about this aspect of scientific history. Is this a straw man? Perhaps, but it is close to what I believed until I started looking more closely at scientific history. In later postings we will see how much of this popular story stands up to closer scrutiny.

The myth about Columbus and the shape of the Earth

In his April 3, 2005 New York Times column called It’s a Flat World, After All, Thomas Friedman begins:

In 1492 Christopher Columbus set sail for India, going west. He had the Nina, the Pinta and the Santa Maria. He never did find India, but he called the people he met “Indians” and came home and reported to his king and queen: “The world is round.”

This is just a throwaway anecdote, to set the frame for another of Friedman’s typical banal outpourings of conventional wisdom. (Sorry to offend the many Friedman fans that are out there but I have never understood his appeal. Not only does he not seem to have any original insights but he also comes across as patronizing and condescending, especially towards the people of other countries.)

But this posting is not meant to poke fun at Friedman, as enjoyable as that might be. That is done much better by Matt Taibbi of the NY Press as he reviews Friedman’s latest book which bears the name The World is Flat. It is instead intended to address one of my pet peeves, the widespread belief that at the time of Columbus’ famous journey, he and almost everyone else believed that the Earth was flat.

This is just not true. So can we all get together and stamp out this myth once and for all?

Thomas Kuhn in his book The Copernican Revolution discusses the early cosmologies and shows quite clearly that the idea of the flat Earth went out very early in recorded history. As early as the seventh century BCE Anaximander of Miletus (624-546 BCE) thought that the Earth was in the shape of a wheel. By the fourth century BCE, most Greek philosophers and astronomers believed in a two-sphere universe, in which the Earth was a tiny sphere, surrounded by a much larger concentric rotating sphere in which the stars were embedded.

The beliefs in the sphericity of the Earth, even back in those early days, were based on careful observations and solid reasoning. The fact that ships moving away had their hulls disappear before the mast, the fact that if you were on high ground, you could see more of the ship than when you were at sea level, the circular edge of the shadow of the Earth on the Moon during lunar eclipses, were all convincing arguments against a flat Earth and educated people of that time accepted them.

In fact, there are references to the measurement of the Earth’s circumference that appear in Aristotle’s (384-322 BCE) writings but the first complete record of this measurement comes from the Eratosthenes (276-194 BCE), the librarian of Alexandria in what is now Egypt, who arrived at a figure that was only off by about 5% from present day measurements, which is remarkable. He obtained this value from observing that the length of the shadow cast by a vertical stick depended on its latitude.

Aristarchus (310-230 BCE) and others in the third century B.C.E had sophisticated measurements of the sizes of the Moon, the Sun, the various distances between them, etc. and all these things were widely known among educated people.

The idea of using the round Earth to sail westward to India was also suggested by geographer Strabo, who was born around 63 BCE.

All this was about 1,500 years before Columbus.

The idea that Columbus and the Spanish nobility may not have been aware of this knowledge is also a myth. Columbus knew the Earth was round as did the other educated people of Spain. The reason that Columbus found it hard to gain support for his expedition was not because people thought he would fall off the edge of the flat Earth, but because Columbus had come up with a dubious calculation for the radius of the Earth that was quite a bit smaller than the accepted value, and it was suspected that he had fudged the calculation in order to make his trip appear more feasible and worth supporting. If the better values for the radius were adopted, then his ships would not have been able to carry enough provisions to reach India.

So Columbus’ arrival in America did not save him from falling off the edge of the Earth, it just saved him and his crew from starvation and death. If America had not been there, his ships would never have been able to make the long trip over the Atlantic and Pacific oceans.

So while it is true that in 1492 there were probably some people who thought that the Earth was flat (as there are probably still people now too), this was not the view of educated people, and definitely not true of Columbus and the people of the Spanish Royal Court.

So why is this myth so resilient? Is it because it makes a dramatic story? Is it still taught in history courses in American schools? Whatever the reason, it is time to put it to rest.