Category Archives: History of Optics

The emergence of modern astronomy – a complex mosaic: Part XXXIX

The emergence of modern astronomy – a complex mosaic: Part XXXIX

One of the most often repeated false statements in the history of science is that Isaac Newton discovered gravity. Of course he didn’t discovery it, it’s all around us. You can observe gravity every time you drop something. Making the claim more precise, by saying Newton discovered the law of gravity, doesn’t really improve the situation much. What Newton did do was he proved the law of gravity and made the fairly rational assumption based on the available evidence that this law applies universally to all bodies in the cosmos. An assumption that is not written in stone and has been questioned in the present time for the general theory of relativity, the theory that replaced the Newtonian theory of universal gravity and of which the Newtonian theory of gravity is a very good approximation for local cases. However we don’t want to take the path to modern theories of cosmology and dark matter but want to stay firmly in the seventeenth century with Newton.

We can start with a brief survey of theories of gravity before Newton. Originally gravity was the Latin term applied to Aristotle’s explanation of why, when dropped, things fall to the ground. Aristotle thought that objects did so through a form of vital attraction, returning to their natural home, consisting predominantly of the elements earth and water. Fire and air rise up. This only applied to the Earth, as things beyond the Moon were made of a fifth element, aether, the quintessence, for which the natural form of motion was uniform circular motion.

This neat model wouldn’t work, however for Copernicus’ heliocentric model, which disrupted the division between the sublunar and supralunar worlds. To get around this problem Copernicus suggested that each planet had its own gravity, like the Earth. So we have terrestrial gravity, Saturnian gravity, Venusian gravity etc. This led Alexander von Humboldt, in the 19th century, to claim that Copernicus should be honoured as the true originator of the universal theory of gravity, although it is by no means clear that Copernicus thought that he planetary gravities were all one and the same phenomenon.

The whole concept became even more questionable when the early telescopic astronomers, above all Galileo, showed that the Moon was definitely Earth like and by analogy probably the other planets too. At the end of a long line of natural philosophers stretching back to John Philoponus in the sixth century CE, Galileo also showed that gravity, whatever it might actually be, was apparently not a vitalist attraction but a force subject to mathematical laws, even if he did get the value for the acceleration due to gravity ‘g’ wrong and although he didn’t possess a clear concept of force.. Throughout the seventeenth century other natural philosophers, took up the trail and experimented with pendulums and dropped objects. A pendulum is of course an object, whose fall is controlled. Most notable were the Jesuit, natural philosopher Giovanni Battista Riccioli (1598–1671) and the Dutch natural philosopher Christiaan Huygens (1629–1695). Riccioli conducted a whole series of experiments, dropping objects inside a high tower, making a direct confirmation of the laws of fall. Both Riccioli and Huygens, who independently of each other corrected Galileo’s false value for ‘g’, experimented extensively with pendulums in particular determining the length of the one-second pendulum, i.e. a pendulum whose swing in exactly one second. As we will see later, the second pendulum played a central roll in an indirect proof of diurnal rotation. Huygens, of course, built the first functioning pendulum clock.

Turning to England, it was not Isaac Newton, who in the 1670s and 80s turned his attention to gravity but Robert Hooke (1635–1703), who was Curator of Experiments for the newly founded Royal Society. Like Riccioli and Huygens Hooke experimented extensively with dropping objects and pendulums to try and determine the nature of gravity. However his experiments were not really as successful as his continental colleagues. However, he did develop the idea that it was the force of gravity that controlled the orbits of the planets and, having accepted that comets were real solid objects and not optical phenomena, also the flight paths of comets. Although largely speculative at this point Hooke presented a theory of universal gravity, whilst Newton was still largely confused on the subject. Hooke turned to Newton in a letter with his theory in order to ask his opinion, an act that was to lead to a very heated priority dispute.

Before we handle that correspondence we need to go back to the beginnings of the 1670s and an earlier bitter dispute between the two.  In 1672 Newton announced his arrival on the European natural philosophy scene with his first publication, a letter in the Philosophical Transactions of the Royal Society (1671/72), A New Theory of Light and Colours, which described the experimental programme that he had carried out to demonstrate that white light actually consisted of the colours of the spectrum.

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Newton’s original letter. Source: Royal Society

This brilliant piece of experimental optics did not receive the universal praise that, reading it today, we might have expected, in fact it was heavily criticised and attacked. Some critics were unable to reproduce Newton’s experimental results, probably because their prisms were of too poor quality. However, others, Hooke to the fore, criticised the content. Hooke and Huygens, the two current leaders in the field of optics both criticised Newton for interpreting his results within the framework of a particle theory of light, because they both propagated a wave theory of light. Newton actually wrote a paper that showed that his conclusions were just as valid under a wave theory of light, which, however, he didn’t publish. The harshest criticism came from Hooke alone, who dismissed the whole paper stating that he had already discovered anything of worth that it might contain . This did not make Newton very happy, who following this barrage of criticism announced his intention to resign from the Royal Society, to which he had only recently been elected.  Henry Oldenburg (c. 1619–1677), secretary of the Royal Society, offered to waive Newton’s membership fees if he would stay. Newton stayed but had little or nothing more to do with the society till after Hooke’s death in 1703. Newton did, however, write a very extensive paper on all of his optical work, which remained unpublished until 1704, when it formed a major part of his Opticks.

By  1679 tempers had cooled and Robert Hooke, now secretary of the Royal Society, wrote to Isaac Newton to enquire if he would be interested in reopening his dialogue with the Royal Society. In the same letter he asked Newton’s opinion on his own hypothesis that planetary motions are compounded of a tangential motion and “an attractive motion towards the centrall body…” Hooke is here referencing his Attempt to Prove the Motion of the Earth from Observations (1674, republished 1679),

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which contains the following fascinating paragraph:

This depends on three Suppositions. First, That all Coelestial Bodies whatsoever, have an attractive or gravitating power towards their own Centers, whereby they attract not only their own parts, and keep them from flying from the, as we observe the earth to do, [here Hooke is obviously channelling Copernicus] but that they do also attract all other Coelestial Bodies that are within the sphere of their activity … The second supposition is this, That all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a streight line, till they are by some other effectual power deflected and bent into a Motion, describing a Circle, Ellipsis, or some other more compounded Curve Line. [the principle of inertia, as propounded by Descartes] The third supposition is, That these attractive powers are so much the more powerful in operating, by how much nearer the body wrought upon is to there own Centers. Now what these several degrees are I have not yet experimentally verified…

Whether or not this is truly a universal theory of gravity is a much-debated topic, but if not, it comes very close and was moving much more in that direction than anything Newton had produced at the time. As we shall see later this was to cause not a little trouble between the two rather prickly men.

Newton declined the offer of a regular exchange of ideas, claiming that he was moving away from (natural) philosophy to other areas of study. He also denied having read Hooke’s paper but referred to something else in it in a later letter to Flamsteed. However, in his reply he suggested an experiment to determine the existence of diurnal rotation involving the usually dropping of objects from high towers. Unfortunately for Newton, he made a fairly serious error in his descripting of the flight path of the falling object, which Hooke picked up on and pointed out to him, if unusually politely, in his reply. Newton of course took umbrage and ended the exchange but he did not forget it.

In our next episode we will deal with the events leading up to the writing and publication of Newton’s great masterpiece, Philosophiæ Naturalis Principia Mathematica (1687), which include the repercussions of this brief exchange between Hooke and its author.

 

 

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Filed under History of Astronomy, History of Mathematics, History of Optics, History of Physics, Renaissance Science

How to create your own Galileo

Writing this book review caused me a great deal of of stress, even leading to sleepless night when I made the mistake of reading the offending piece of literature as bedtime reading. The review itself has become horrendously long and I must at times fight my instinct to add even more explanations, as to why this or that was wrong. It is in the words of that excellent history of science author, Matthew Cobb, ‘baggy and rambling’ and should actually be radically edited but I just can’t be arsed to do it, so I’m simply posting the whole monstrosity. For those, who don’t want to read the whole thing, and I wouldn’t blame you, the first three and the last five paragraphs offer a sort of synopsis of the whole thing.

Since I began writing book reviews on a more regular basis I have tried only to review books that I personally find good and which I think might be of interest to those who come here to read my weekly scribblings. I decided that on the whole it isn’t worth wasting time and energy writing about uninteresting, mediocre or simply bad books. However, occasionally a book come along that I feel duty bound, given my reputation as a #histSTM grouch, to debunk as a favour to my readers so that they don’t waste their time and energy reading it; today’s review is one such.

Some time back I wrote a post about the Alexandrian mathematician and philosopher Hypatia, which started with the fact that she has been used as a sort of blank slate onto which numerous people down the centuries have projected their images of what they would have wanted her to be. In the case of Hypatia this is fairly easy, as the rest of my post pointed out we know next to nothing about the lady. Another figure, who has been used extensively over the years as a silhouette, which people fill out according to their own wishes is Galileo Galilei; in his case this is more difficult as we actually know an awful lot about the Tuscan mathematician’s life and work. However, this has not prevented numerous authors from creating their own Galileos.

The latest author, who has decided to present the world with his Galileo, is the astrophysicist and very successful author of popular books on mathematics and science, Mario Livio with his Galileo and the Science Deniers.[1] I might not have bothered with this book but Livio is a very successful pop science book author, as is made very clear by the fact that the hardback and paperback were both issued simultaneously and at very low prices; the publishers expect it to sell well, so it will unfortunately have a big impact on uninformed peoples perceptions of Galileo. I say unfortunately, which, of course, gives readers of this review a very strong clue as to what I think of this book. Quite simply don’t bother, it brings nothing new to our knowledge of Galileo and in fact is full of, at times, quite serious historical errors, serious that is if you’re a historian, who takes getting the facts right seriously.

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The opening sentences starts with a couple of wonderful errors and also lays out Livio’s version of Galileo:

Being an astrophysicist myself, I have always been fascinated by Galileo. He was, after all, not only the founder of modern astronomy and astrophysics–the person who turned an ancient profession into the universe’s deepest secrets and awe-inspiring wonders–but also a symbol of the fight for intellectual freedom.

I think Copernicus, Tycho Brahe and Johannes Kepler might want a word with Livio about, who exactly is the founder of modern astronomy. Also, excuse the language, but what the fuck did Galileo ever do for astrophysics? The final half sentence tells us into which silhouette Livio has decided to pour his Galileo; Livio’s Galileo is the white knight of freedom of speech and freedom of thought, who has mounted his charger and taking up his lance sets off to kill the anti-science dragon of the Holy Roman Catholic Church. This is, of course not a new Galileo but a well-known old model, which historians of science have spent a lot of time and effort dismantling over the last fifty plus years.

Central to the problems with Livio’s book is that he completely ignores the historical context in which the Galileo story took place. His is totally a presentist view in which he applies the social rules and moral judgements of the twentieth-first century to the various occurrences he sketches in the early seventeenth century. This is quite simply very bad historiography. He compounds this error by trying to draw parallels between Galileo’s conflict with the Catholic Church and the current problems with science denialists in our times, hence the title of his book. To do this he simply denies Galileo’s critics any scientific basis for their criticism whatsoever, Galileo is science, his critics are anti-science. A rather simplistic and historically highly inaccurate presentation of the known facts.

Just to make clear what exactly the historical context was, there existed no freedom of speech or freedom of thought under any civil or religious authority anywhere in Europe at the beginning of the seventeenth century; such social concepts still lay in the future. There is a slight irony in the fact that the current wave of science denialists, against whom Livio’s book is directed, are in fact exercising their, protected by law, rights of freedom of thought and speech. More importantly the Holy Roman Catholic Church was not just a religion and a church but also a powerful political and judicial body with judicial rights over all within its dominion and this in an age of absolutism with the Pope as the most absolute of all absolute rulers. All authorities both civil and religious reserved for itself the right to determine what its subject were permitted to express in public, the Catholic Church was in no way unique in claiming and exercising this right.

Still in the preface to Livio’s book we find his first distortion of the historical scientific facts, he writes that Galileo’s telescopic discoveries, “All but destroyed the stability of the Earth-centered Ptolemaic universe.” Here Livio, and not only here, fails to differentiate between Aristotelian cosmology and Ptolemaic astronomy. All of the telescopic discoveries, with the exception of the phases of Venus, demolished aspects of Aristotelian cosmology but had no significance for Ptolemaic geocentric astronomy. The discovery of the phases of Venus, of course, refuted a pure geocentric system but was perfectly compatible with a Tychonic geo-heliocentric system, which then became the default alternative to a heliocentric system. With two notable exceptions that I will deal with later Livio makes no clear mention of the fact that the telescopic discoveries were made within the same approximately three year period not only by Galileo but simultaneous by others, so if Galileo had never used a telescope it would have made very little difference to the subsequent history of astronomy. This makes rather a mockery of Livio’s next dubious claim, “his [Galileo’s] ideas became the basis on which modern science has been erected.” This is much less true than Livio and other Galileo groupies would have us believe. Galileo made a contribution but others in the seventeenth century actually contributed significantly more.

One last comment from the preface, Livio writes:

He insisted on publishing many of his scientific findings in Italian [actually Tuscan not Italian] (rather than Latin), for the benefit of every educated rather than for a limited elite.

In the early seventeenth century almost every educated person would per definition have been able to read and write Latin; Latin was the default language of education.

Reading the opening chapter of Livio’s book, Rebel with a Cause, I constantly had the feeling that I had been transported back to the 1960s and 70s, when I first began to read books about the history of science in general and Galileo in particular. It as if the last fifty plus years of history of science research had never taken place, he even relies on Einstein and Bertrand Russell as his historical authorities, at times I shuddered. He goes so far as to tell us that the Renaissance happened because people discovered that they were individuals! I can’t remember when I last read this particular piece of inanity and I would be curious who actually put it into the world. The final page of this chapter contains all of the classic Galileo clichés.

Perhaps most important, Galileo was the pioneer and star of advancing the new art of experimental science. He realised that he could test or suggest theories by artificially manipulating various terrestrial phenomena. He as also the first scientist whose vision and scientific outlook incorporated methods and results that were applicable to all branches of science.

There is a long historical list of people who would disagree–Archimedes, Ptolemaeus, al-Haytham, Grosseteste, Roger Bacon, William Gilbert and a whole host of alchemists starting with Abū Mūsā Jābir ibn Hayyān (for Livio opinion on alchemy see below)–just to name the most prominent. Modern research has also conclusively shown that artisanal practice in the fifteenth and sixteenth centuries played a significant role in the development of empirical, experimental science. Livio’s last sentence here is also rather dubious, apart from some rather trivial aspects, there are no methods and results that are applicable to all branches of science.

…in four areas he revolutionised the field: astronomy and astrophysics; the laws of motion and mechanics; the astonishing relationship between mathematics and physical reality […]; and experimental science.

Despite everything, Galileo’s contributions to astronomy were rather minimal and he certainly didn’t revolutionise the field, others such as Kepler, whom he ignored, did. I am still trying to work out what his contributions to astrophysics could possibly be? His real major contribution was indeed to motion and mechanics but he was no means alone in this others such as Simon Stevin and Isaac Beeckman made substantial contributions to the new developments in these areas. The mathematics thing, to which Livio keeps returning, is baloney and I shall deal with it separately later. Galileo made contributions to the development of experimental science but he was by no means alone in this and to say he revolutionised it is hyperbole.

The only defense remaining to those obstinately refusing to accept the conclusions implied by the accumulating weight of empirical facts and scientific reasoning was to reject the results almost solely on the basis of religious or political ideology

Here Livio betrays his own tactic, put crudely, throughout the book he twists the historical facts in order to try and make out that there no legitimate scientific objections to Galileo’s claims, however there were.

The next chapter is the usual enthusiastic fan boy description of Galileo’s talents as an all round humanist and contains nothing particularly objectionable but does contain a strong indication of the superficiality of Livio’s historical knowledge. He writes, “First, at age twenty-two, Galileo, already had the chutzpah to challenge the great Aristotle on topics related to motion…” People had been consistently challenging the great Aristotle on topics related to motion since the sixth century CE and Galileo was merely joining a long tradition of such work. Livio also casually calls Aristotle’s theory of motion impetus! Impetus was, of course, a theory initially developed by John Philoponus in the sixth century CE when seriously challenging Aristotle’s theory of motion. On a side note Livio says that the tools to treat such variables such as velocity and acceleration, i.e. calculus, were first developed by Newton and Leibniz. Other seventeenth century mathematicians who contributed substantially to the development of the calculus such as Cavalieri, de Saint-Vincent, Fermat, Pascal, Descarte, John Wallis and Isaac Barrow would be very surprised to hear this. On the same page he repeats the myth that Christoph Clavius was “the senior mathematician on the commission that instituted the Gregorian calendar, he wasn’t, Ignazio Danti was.

Clavius turns up as one of the leading mathematicians, who the young Galileo turned to for mentorship when he was trying to establish a reputation as a mathematician and get support to find an appointment as professor of mathematics. Interestingly Galileo’s other mentor Guidobaldo del Monte (1545–1607) appears nowhere in Livio’s book. This is strange as it was del Monte, who acquired the professorship in Pisa for Galileo through his brother Cardinal Francesco Maria del Monte (1549–1627), who was the de ‘Medici cardinal and recommended Galileo to the Grand Duke. It was also del Monte, who devised the experiment that led Galileo to the parabola law, which Livio calls one of Galileo’s crowning achievements.

In the next chapter on Galileo’s work on the theory of fall Livio can’t help taking a sideswipe at alchemy and astrology:

It is certainly true that, at their inception, the sciences were not immune to false beliefs, since they are sometimes connected to fictitious fields such as alchemy and astrology. This was partly the reason why Galileo decided later to rely on mathematics, which appeared to provide a more secure foundation.

This off hand rejection ignores completely that astrology was the main driving force behind astronomy since its beginnings in antiquity down to the seventeenth century and that all the leading Renaissance astronomers, including Galileo, were practicing astrologers. The practice of astrology/astronomy, of course, requires a high level of mathematical ability. Alchemy developed virtually all of the experimental methods and the necessary equipment to carry out those experiments on which chemistry was built.

Now in Padua, where Galileo was also professor of mathematics, a position that he once again acquired with the assistance of del Monte, we get the story of Galileo’s three lectures on the nova of 1604. Livio informs us that “Christoph Clavius confirmed the null parallax determination–that is, no shift had been observed–but refused to accept its implications as compelling.”

This is once again Livio’s tactic of trying to discredit the Jesuits. The implications that he is talking about are that the heavens are not unchanging as claimed by Aristotle. Clavius observed the nova of 1572 and already in 1581 published a digression on the subject fully accepting that the nova was supralunar and that the heavens were not unchanging. He included this in his Sphaera in 1585, the most widely read astronomy textbook in the late sixteenth and early seventeenth centuries and he probably thus had the most influence in persuading others that change had occurred in the heavens. He also included the same results for the novae of 1600 and 1604, so what is Livio talking about? Clavius was unable to explain what these novae were but then again nobody else in the seventeenth century could either.

We now move on to Galileo, telescopic astronomy and the Sidereus Nuncius. Although he actually talks about other telescopic astronomers–Scheiner, Marius, Harriot, Fabricius–they are only offered bit parts in Livio’s screenplay, which follows the usual path of giving Galileo credit for everything. He attributes the discovery of Earthshine, the Moon illuminated by sunlight reflected by the Earth, to Galileo, whereas it was previously discovered by Leonardo, who didn’t publish, and Michael Mästlin, who did. He attributes the discovery of stars that can’t be seen without a telescope to Galileo, whereas this was already noted in the printed account of the first telescope demonstration in Den Hague, the source of Sarpi’s and thus Galileo’s first knowledge of the telescope. We then get one of the most bizarre claims made by Livio in the book:

Even more consequential for the future of astrophysics was Galileo’s discovery that stars varied enormously in brightness, with some being a few hundred times brighter than others.

Coming from a professional astrophysicist I find this statement mind boggling. The difference in brightness between celestial objects is obvious to anybody with reasonable eyesight, who simply looks up at the night sky in an area without light pollution. Astronomers even use a six-point scale to designate the different levels of brightness, which is termed magnitude; this was first introduced by Ptolemaeus around 150 CE!

We then get a very brief account of the star size argument as originated by Tycho, which Livio falsely claims Galileo dismissed by saying that the observed star discs are merely artefacts. They are in fact merely artefacts but Galileo didn’t say this. He accepts their existence and uses a completely different argument to try and dismiss the star size argument.

We now arrive at the Moons of Jupiter and Simon Marius. Livio mentions Marius several times in his book but insists on calling him Simon Mayr, his birth name, why? Marius issued all of his publications under the Latinised version of his name and so historian refer to him as Simon Marius. Livio doesn’t call Copernicus, Kopernik or Tycho, Tyge their birth names, so why does he call Marius, Mayr? What he writes about Marius and the Moons of Jupiter left me, as a Marius expert, totally flabbergasted:

What would have undoubtedly annoyed Galileo no end is that the Galilean satellites are known today by the names assigned to them by the German astronomer Simon Mayr rather than as the “Medici stars.” Mayr may have independently discovered the satellites before Galileo, but he failed to understand that the moons were orbiting the planet. [my emphasis]

First off, the names were suggested by Kepler not Marius, who however first published them specifically mentioning the fact that they were suggested by Kepler. Secondly Marius discovered the moons, famously, one day later than Galileo, any confusion about who discovered what when being produced by use of different calendars, Gregorian and Julian. Thirdly, the clause that I have emphasised above is pure and utter bullshit. Marius knew very well that the moons orbited Jupiter and he calculated the orbits, calculations that he published before Galileo. Marius’ calculations are also more accurate than those of Galileo. Should Livio doubt any of this I can send him scans of the relevant pages of Mundus Jovialis in the original Latin or in German and/or English translation. Livio now brings the story of Galileo hating Marius because he accused him of being behind Baldessar Capra’s plagiarism of Galileo’s proportional compass pamphlet in 1606. Marius had been Capra’s mathematics teacher earlier in Padua. Livio fails to mention that the accusations are provably false. Galileo in 1607 had himself cleared Marius of any involvement in the case and the whole episode took place a year after Marius had left Padua.

We now move on to the peculiar shape of Saturn and the discovery of the phases of Venus. In the later case we get absolutely no mention that the phases of Venus were discovered independently by Harriot, Marius, and the astronomers of the Collegio Romano, the latter almost certainly before Galileo. Livio notes correctly that the discovery of the phases definitively refutes the possibility of a pure geocentric system. However, it does not refute a geo-heliocentric Tychonic system. Livio admits this very grudgingly:

…but could not definitely dispose of Brahe’s geocentric-heliocentric compromise […]. This left a potential escape route for those Jesuit astronomers who were still determined to avoid Copernicanism.

Throughout his book Livio tries to imply that there is no real justification for supporting the Tychonic system, whereas it was not only the Jesuits, who did so but many other astronomers as well because the empirical evidence supported it more that a heliocentric one, of which more later. However, Livio consistently ignores this fact because it doesn’t fit his fairy-tale narrative.

Livio deals fairly conventionally with the telescopic discovery of sunspots and the discussion on their nature between Galileo and Christoph Scheiner and although he ends his account by noting the publication of Scheiner’s Rosa Ursina sive Sol (1626–1630) he makes no mention of the fact that the book is a masterpiece of astronomy, far better than anything Galileo published in the discipline. As should always be noted, due to the haste in which he wrote and published it, Sidereus Nuncius was closer to a press report than a scientific publication. He does however mention, what he calls “some further comments he made later in the book The Assayer, which the Jesuit astronomer took to be directed at him personally, did turn him into an unappeasable enemy.” Galileo actual vehemently and totally falsely accused Scheiner of plagiarism in The Assayer, which he later compounded by plagiarising Scheiner’s work in his own Dialogo. Scheiner’s antagonism is understandable. We now get the real reason why Livio keeps badmouthing the Jesuits; he sees them as behind Galileo’s trial in 1633. He writes, “This marked just the beginning of a conflict with the Jesuits, which would culminate in the punitive actions against Galileo in 1633.” This is an old myth and quite simply not true, the Jesuits did not come to Galileo defence but they were also not responsible for his trial.

We now come to objections to the telescopic discoveries:

How could anyone be sure that what Galileo was seeing was a genuine phenomenon and not a spurious artifact produced by the telescope itself?

Not only wasn’t there a convincing theory of optics a that could demonstrate that the telescope doesn’t deceive, they contended but also the validity of such a theory in itself based on mathematics, was questionable. [my emphasis]

 

Livio tries to imply that both objections are just anti-science nit picking but they are in fact very solid, very necessary scientific question that had to be asked and to be answered if people were going to accept the validity of the telescopic discovery. To the first general objection, although Galileo, an excellent observer, made none himself, there were numerous cases of published discoveries that turned out to be merely optical artefacts in the early years of telescopic astronomy. Not really surprising given the really poor quality of the instruments being used, Galileo’s included.

That an optical theory of the telescope didn’t exist was a very serious problem, as it would be with any new scientific instrument. If you can’t explain how the instrument works how do you expect people to accept the results? Kepler solved the problem with his Dioptrice published in 1611, which explained fully and scientifically how lenses and lens combinations function, describing various different types of telescope. Galileo dismissed and mocked, what is now regarded as a milestone in the history of geometrical optics. The last clause is, once again, Livio spouting total crap. Theories of optics had been geometrical, i.e. mathematical, since at least, in the fourth century BCE and even Aristotle classified optics as one of the mixed sciences, i.e. those such as astronomy that are dependent on mathematics for their proofs. Kepler’s book was accepted by all those qualified to pass judgement on the matter, with the notable exception of Galileo, who didn’t want to share the limelight with anybody, and together with Kepler’s earlier Pars Optica (1604) formed the foundations of modern scientific optics.

The reference to mathematics here is Livio’s attempt to create or propagate a myth that before Galileo, nobody conceived of a mathematics-based science. It is time to tackle that myth. Livio argues that Aristotle rejected mathematics in science and that Aristotelians regarded anything proof based on mathematics as not valid. He, of course, finds an obscure Aristotelian contemporary of Galileo’s to quote to prove this but does not quote any evidence to the contrary or even appear to think that some might exist. He is very wrong in this. Because, in Aristotle’s opinion, mathematics does no deal with the real world the results of mathematic are not episteme or scientia or as we would say knowledge. He however makes allowances for the so-called mixed sciences, astronomy, optics and statics. Livio acknowledges this status for astronomy but argues with the medieval Aristotelians that astronomical mathematical models are mere calculating devices and not models of reality; describing cosmological reality was the domain of the philosophers and not the mathematical astronomers. He also claims that this was still the situation in the second decade of the seventeenth century, it wasn’t. Beginning with Copernicus astronomers began to claim that their mathematical models were models of reality and by the time of Galileo’s first dispute with the Catholic Church this had become the generally accepted state of the discipline. The debate was which mathematical model describes the real cosmos?

It is a standard cliché in the history of science that one of the major factors that drove the so-called scientific revolution was the mathematization of science. Like many clichés there is more that a modicum of truth in this claim. Livio believes it is absolutely central and one of the major themes of his book is that Galileo was the first to mathematize science in his experiments on motion and the laws of fall. This is quite simply not true and Livio can only maintain his claim by steadfastly ignoring the history of mathematics in science prior to Galileo or did he even bother to look if there was any?

Starting with Galileo’s researches into motion and fall there is a three hundred year history of experimental and mathematical investigation into exactly this area starting with the Oxford Calculatores, who derived the mean speed theorem, which lies at the heart of the laws of fall and going down to Giambattista Benedetti (1530–1590), who produced all of the arguments and thought experiments on the subject for which Galileo is famous. There is much more, which I have already dealt with in an earlier post and won’t repeat here.Galileo knew of all of this work. The Archimedean renaissance in mathematics and the sciences, replacing the authority of Aristotle with that of Archimedes, in which Galileo is a major figure, does not start with Galileo but goes back at least to Regiomontanus (1436–1476).  The works of Archimedes were edited by Thomas Venatorius (1488–1551) and printed and published in a bilingual Greek and Latin edition in Basel in 1544. In general the sixteenth century saw a massive increase in the application of mathematics to a wide range of subjects, a development that was already well underway in the fifteenth century, including linear perspective in art, cartography, surveying, navigation, physics and astronomy. Galileo in no way started the mathematization but represents, together with several of his contemporaries such as Johannes Kepler, Simon Stevin, Christoph Clavius and Isaac Beeckman, a temporary high point in these developments. All four of those contemporaries were actually better mathematicians than Galileo.

On the question of the epistemological status of mathematical proofs, which Livio clearly states was still doubted in Galileo’s time, Christoph Clavius, who many people don’t realise was an excellent epistemologist, had already changed perceptions on this when Galileo was still a child. Clavius a Jesuit and thus by definition a Thomist Aristotelian used Aristotle’s own arguments to demonstrate that mathematical proofs have the same epistemological status as philosophical proofs. He even went to the extent of translating parts of the Elements of Euclid into Aristotelian syllogisms to show that mathematical proofs transport truth in the same way as philosophical, logical ones. Clavius’ influence was massive, he fought to get mathematics accepted as part of the educational reform programme of the Jesuits and then got the mathematical sciences established as a central part of the curriculum in Catholic schools, colleges and university also training the necessary teachers to carry out his programme. There is a reason why the young Galileo turned to Clavius, when seeking a mentor for his mathematical ambitions.

Taking all of this together the roll of mathematics and status of mathematical proofs in the sciences was very different in the early seventeenth century than the picture that Livio serves up. Far from being ground breaking Galileo’s (in)famous quote from The Assayer  “the book of nature is written in the language of mathematics” (which Livio offers up several times in his book) was actually stating a truth that had been generally accepted by many natural philosophers and mathematicians for many decades before Galileo put pen to paper.

Returning to Galileo’s telescope discoveries, Livio tells us that Kepler published his letter praising Galileo’s telescopic discoveries under the title Dissertio cum Nuncio Sidero (1610) then goes on to write: “Galileo was clearly pleased with its content, the letter was reprinted in Florence later in the year.” What Livio neglects to mention is that Galileo was responsible for that edition in Florence, which was a pirate edition published without Kepler’s knowledge and without his permission or consent. Livio makes it appear that the Jesuit astronomers of the Collegio Romano only reluctantly started to try and confirm Galileo’s discoveries and then only when ordered to do so. This is a complete distortion of what actually happened.

The astronomers in the Collegio Romano had their own telescopes and had been making astronomical telescopic observations well before Galileo published the Sidereus Nuncius. They immediately leapt on the pamphlet and set out to try and confirm or refute his observations. They had some difficulties constructing telescopes good enough to make the necessary observations and Christoph Grienberger (1561–1636), who was acting head of the school of mathematics due to Clavius’ advanced age, corresponded with Galileo, who provided copious advice and tips on observing and telescope construction. This was a work of friendly cooperation under fellow mathematicians. After some difficulties they succeeded in providing the necessary confirmation, which they made public and celebrated by throwing a banquet for Galileo when he visited Rome in 1611. As already stated above the Jesuit astronomers probably observed the phases of Venus before Galileo.

Livio then goes on to draw parallels with the fact that, “The current debate on global warming had to go […] through a similar painful [my emphasis] type of confirmation process.” I find this statement, quite frankly, bizarre coming from a scientist. All scientific discoveries have to be independently confirmed by other scientists, it is a central and highly important part of the whole scientific process. What the astronomers of the Collegio Romano did for Galileo was in no way “painful” but a necessary part of that scientific process for which Galileo was very thankful. I find it particularly bizarre given the very lively current debate on the significant number of scientific papers that have to be retracted because of failing confirmation. Reading Livio in the worst possible light, and not just here but at numerous other points in his narrative, he seems to be saying, if Galileo says it is so, then it must be true and anybody, who dares to criticise him, is in the wrong.

Of course, Livio cannot avoid the myth that, “First Copernicus and Galileo removed the Earth from its central position in the solar system.” Having previously quoted the “Copernicus principle”: the realisation that the Earth, and we human beings, are nothing special…” Also: “ What’s more the Copernican system was bound to be at odds with a worldview that had placed humans at the very center of creation, not only physically but also as a purpose and focus of for the universe’s existence.” Although geometrically central, the philosophers and astronomers in the Renaissance did not regard the Earth’s position as central in any special way. It was far more the bottom, the dregs of the universe. Trying to move the Earth into the heavens was moving it into an exalted place. At least Livio is honest enough to admit that Galileo remained blind to Kepler’s work, although Livio reduces it to just the discovery of elliptical orbits, whereas Kepler actually contributed more to modern astronomy than Copernicus and Galileo together.

Livio now moves on to Galileo’s entry into theology and his Letter to Castelli. As with all Galileo apologists, whist admitting that Galileo was trespassing in the territory of the theologians, he thinks that Galileo was right to do so and what he wrote was eminently sensible and should have been acknowledged and accepted. What Galileo did struck at the vey heart of the Reformation/Counter Reformation dispute that had been raging in Europe for one hundred years and just three years later would trigger the Thirty Years War, which devastated central Europe and resulted in the death of somewhere between one and two thirds of the entire population. The Catholic Church had always claimed that they and only they were permitted to interpret Holy Scripture. Luther claimed in opposition to this that every man should be allowed to interpret it for themselves. This led to schism and the Reformation. The Catholic Church confirmed, with emphasis, at the Council of Trent that only the Church’s own theologians were permitted to interpret the Bible. Now along comes a mere mathematicus, the lowest rang in the academic hierarchy, and cheerfully tells the theologians how to interpret the Holy Writ. The amazing thing is that they didn’t simply throw him into a foul dungeon and throw away the key.  I mentioned earlier that the Church was a judicial organ and the decisions of the Council of Trent were binding laws on all Catholics. Galileo knowingly and very provocatively broke that law and got mildly and unofficially admonished for doing so. Whatever a modern observer may think about the quality of Galileo’s theological arguments is completely irrelevant, it’s the fact that he made them at all that was the offence. However, in doing so he together with Foscarini provoked the Church into taking the heliocentric hypothesis under the microscope. He had been warned, as early as 1613, by various friends including Cardinal Maffeo Barberini, the future Pope Urban VIII not to do so.

Livio thinks that because he finds Galileo’s arguments in the Letter to Castelli reasonable and ‘because of science’ that the Catholic Church should have cut Galileo some slack and let him reinterpret the Bible. The Catholic Church should abandon their exclusive right to interpret Holy Writ, one of the fundaments of their entire religion, so that a nobody, and despite his celebrity status, in the grand scheme of things Galileo was a nobody, could promote an unproven astronomical hypothesis! This is the same exclusive right for which the same Church was prepared to engage in one of the most devastating wars in European history, just three years later. In his pseudo-historical narrative Livio has here completely lost touch with the historical context.  In fact Livio is not writing history at all but making presentist moral judgements with hindsight.

There is another bizarre statement by Livio where he writes:

All this notwithstanding, however, the Church might have still accommodated (albeit with difficulty) a hypotheticalsystem that would have made it easier for mathematicians to calculate orbits, positions, and appearances of planets and stars as long as such a system could be dismissed as not representing a true physical reality. The Copernican system could be accepted as a mere mathematical framework: a model invented so as to “save the appearances” of astronomical observations–that is, to fit the observed motion of the planets.

I am frankly baffled by this paragraph because that is exactly what the Church did in fact do. They fully accepted heliocentricity as a hypothesis, whilst rejecting it as a real physical description of the cosmos. This is shown very clearly by their treatment of Copernicus’ De revolutionibus, which unlike Kepler’s books, for example, was not placed on the Index of forbidden books but was only placed on it until corrected. This correction was carried out by 1620 and consisted only of changing or removing the comparatively few statement in the book claiming that heliocentricity was a real physical description of the cosmos. From 1621 Catholics were free to read the now purely hypothetical De revolutionibus. Livio relates all of this fairly accurately and then drops another clangour. He writes:

In reality, the modifications introduced by Cardinal Luigi Caetani and later by Cardinal Francesco Ingoli were indeed relatively minor and the publication of the revised version was approved in 1620. However, the new edition never reached the press, and so Copernicus’s book remained on the Index of Prohibited Books until 1835!

This is once again complete rubbish. The Catholic Church never intended to publish a new or revised edition of De revolutionibus. What they did was to issue the list of corrections deemed necessary and every Catholic owner of the book was expected to carry out the corrections in the own copies themselves. Quite a few obviously did and we have a number of surviving copies, including Galileo’s own private copy, with the corrections carried out according to the issued instructions. Interestingly almost all of the thus censored copies are in Italy or of Italian provenance, it seems that Catholics outside of Italy didn’t take much notice of the Vatican’s censorship order. De revolutionibuswas of course removed from the Index in 1620 having been corrected. Also, I know of no case of anyone being prosecuted for reading or owning an uncensored copy of the book.

Livio tries to counter the argument that I have presented above that Galileo was admonished because he meddled in theology by claiming that the motivation was one of anti-science. Livio. “[They] were trying only to convince Galileo not to meddle in theology, as a few modern scholars have concluded.” To counter this he brings statements from Grienberger and Bellarmino saying that elements of Copernicus theory contradict passages of Holy Writ. He writes:”[they] were quite intent on crushing the Copernican challenge as a representation of reality because, from their perspective, they were vindicating the authority of Scripture in determining truth.” Dear Dr Livio that is theology! As Bellarmino wrote in his letter to Foscarini, if a contradiction exists between Holy Writ and a proven scientific fact, the heliocentric hypothesis was of course at this point in time no where near being a proven scientific fact, then the theologians have to very carefully considered how to reinterpret Holy Writ; that is what theologians do!

This brings us to Roberto Bellarmino famous letter to Paolo Antonio Foscarini. Foscarini, a monk, had written a book defending heliocentricity and reinterpreting the Bible in a similar way to Galileo. Criticised, he sent his book to Roberto Bellarmino for his judgement; he hoped it would be favourable. The title contains the word Pythagorean, so Livio explains that the Pythagoreans thought Earth etc. orbited a central fire, therefore the comparison with Copernicus’ theory. Livio then writes, “Greek philosopher Heraclides of Pontus added, also in the fourth century BCE that the Earth rotated on its axis too…” As far as can be determined Heraclides proposed diurnal rotation in a geocentric system and not in a heliocentric or Pythagorean one.

Livio goes into a lot of detail about Foscarini’s text and Bellarmino’s letter but I will only mention two points. Livio quotes the paragraph that I have already paraphrased above, “…if there were a true demonstration that the sun is at the center of the world and the earth in the third heaven, and that the sun does not circle the earth but the earth circles the sun, then one would have to proceed with great care in explaining the Scriptures that appear contrary, and say rather that we do not understand them, than what is demonstrated is false.” Livio adds, “But I will not believe that there is such a demonstration, until it is shown me. Nor is it the same to demonstrate that by supposing the sun to be at the center and the earth in heaven one can save the appearances, and to demonstrate that in truth the sun is at the center and the earth in the heaven; for I believe the first demonstration may be available, but I have very great doubts about the second, and in case of doubt one must not abandon the Holy Scripture as interpreted by the Holy Fathers.”

This is of course eminently sensible and rational. If you want me to accept you scientific theory then show me the proof! Livio doesn’t accept this and goes of into a long diatribe, which demonstrates his own prejudices rather more than any faults in Bellarmino’s logic. He then comes with a totally spurious argument:

If two theories explain all the observed facts equally well, scientists would prefer to adopt, even if tentatively, the simpler one. Following Galileo’s discoveries, such a process would have definitely favoured the Copernican system over the Ptolemaic one, which was what Galileo had been championing all along. The requirement of simplicity would have also given an advantage to Copernicanism over Tycho Brahe’s hybrid geocentric-heliocentric model.

Ignoring the fact that the Ptolemaic system was dead in the water after the discovery of the phases of Venus and so the comparison is a waste of time, any alert reader will immediately spot the massive error in this argument. The two theories, Copernicus and Brahe, do not explain all the observed facts equally well. The Copernican system requires something very central that the Tychonic system does not, terrestrial motion. Livio adds this in a very off hand way, “Of course the ultimate test would have been to find direct proof for the Earth’s motion…” There was in fact absolutely no empirical proof of the Earth’s motion and wouldn’t be until Bradley discovered stellar aberration in 1725! To give the “advantage to Copernicanism over Tycho Brahe’s hybrid geocentric-heliocentric model” would be under the circumstances actually unscientific.

A little bit further on Livio delivers another highly spurious comment, he writes, “…but Bellarmino’s position was extremely rigid. He did not believe that a proof of Copernicanism could ever be found.” Livio is here putting words into Bellarmino’s mouth, who never said anything of the sort, rather he expressed doubt that that such a proof existed.  Livio finishes off his series of spurious attacks on Bellarmino by claiming to prove him theologically wrong. I find it slightly amusing that a twenty-first century astrophysicists claims that Bellarmino, who was universally regarded as the greatest living Catholic theologian and whose reputation as a theologian was such that at the end of his life he was both head of the Index and head of the Inquisition, was theologically wrong.

Things developed as they must and we now have Galileo rushing off to Rome to try and rescue the situation with his infamous theory of the tides. Livio explains the theory and its possible origins then he drops the following jewel:

Albeit wrong, Galileo’s commitment to mechanical easy-to-understand causation made his theory of tides at least plausible.

There is only one possible answer to this claim, bullshit! A theory that states there is only one high tide and one low tide at the same time every day, when there are in fact two of each of which the times travel around the clock over the lunar month (a strong indication of the correct theory of the tides) is anything but a plausible theory. It is as I said bullshit.

We now turn to the committee of consultors set up to examine the theological implications of heliocentricity. Livio of course has much to say against this. His first objection:

Ironically, the same office that had objected vehemently to scientists intruding into theology was now asking the theologians to judge on two purely scientific questions–two of the central tenets of he Copernican model.

Once again Livio appears to have no idea what theology is. The discipline of theology covers all forms of human activity in their entirety. There is absolutely nothing in human existence that doesn’t fall under the remit of theology. Secondly the function of the consultors in this case were being asked to examine the two central tenets of heliocentricity in relation to Catholic religious belief, not a scientific question at all.

Next up, Livio objects to the consultors themselves: “Not one was a professional astronomer or even an accomplished scientist in any discipline.” All of the consultors were highly educated, learned men, who would have had a solid instruction to Ptolemaic astronomy during there education and were more than capable of asking an expert for his advice if necessary.

Consultor: Is there any empirical evidence that the Earth moves and the Sun stands still?

Astronomer: No

Consultor: Is there any empirical evidence that the Sun and not the Earth is at the centre of the cosmos?

Astronomer: No

Simple wasn’t it.

 

The decisions of the consultors are well know:

On February 24 the Qualifiers delivered their unanimous report: the proposition that the Sun is stationary at the centre of the universe is “foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture”; the proposition that the Earth moves and is not at the centre of the universe “receives the same judgement in philosophy; and … in regard to theological truth it is at least erroneous in faith. (Wikipedia)

Foolish and absurd in philosophy is the scientific judgement and sounds somewhat harsh but can be simply translated as, is not supported by the available empirical evidence. Livio would disagree with both the judgement and my interpretation of it but it is historically fundamentally accurate. The second part of each judgement is of course the theological one. As is also well known the Pope commissioned Cardinal Bellarmino to inform Galileo of the decision and to instruct him not to hold or teach the heliocentric theory. Books, such as those of Kepler, claiming the physical reality of heliocentricity, were placed on the Index and De revolutionibus, as detailed above until corrected, which it was.

Bewilderingly Livio accuses Bellarmino and the Jesuits of failing to support Galileo against the Pope, which displays an incredible ignorance of the Catholic Church, the Pope and the Jesuit Order in the seventeenth century. As stated at the beginning the Catholic Church was a religious, political and judicial power in an age of absolutism and the Pope was an absolutist ruler. The Society of Jesus (Jesuits), and Bellarmino was also a Jesuit, is a religious order dedicated to and directly under the authority of the Pope. Livio’s accusations are totally insane.  He, of course, can’t resist making ahistorical and inaccurate comments about the decision, he writes:

The ruling made by officers of the Church for whom retaining authoritative power over areas totally outside their expertise took priority over open-minded critical thinking informed by scientific evidence.

Livio here continues to ignore/deny the simple fact that the scientific evidence in the early seventeenth century simply did not support an interpretation of heliocentricity as a physical reality and whilst it appears somewhat draconian the Church decision doesn’t actually say anything else.

Livio also launches the presentist moral outrage attack, “[some] argue that some of the responsibility for the prohibition of Copernicanism lies with Galileo himself, because he wouldn’t keep his mouth shut. Such claims are outrages.” Firstly the heliocentric hypothesis was never prohibited only the heliocentric theory, which given its scientific status at the time was in fact, although unnecessarily harsh, justifiable and secondly if Galileo had displayed somewhat more tact, instead of behaving like the proverbial bull in a china shop, things would never have taken the turn that they did.

We move on to the dispute over the nature of comets between the Jesuit astronomer Orazio Grassi and Galileo. Here Livio again displays his ignorance of the history of astronomy. He writes:

Grassi’s theory of comets deviated courageously from the Aristotelian view, which placed comets at about the distance of the Moon. Instead following Tycho Brahe, Grassi proposed that the comets were further out between the Moon and the Sun.

[…]

As to the actual nature of comets, many astronomers at the time were sill adopting Aristotle’s theory, which stated that these represented exhalations of the Earth that became visible above a certain height due to combustion, disappearing from view as soon as that inflammable material was exhausted. Grassi, however, again followed Brahe in suggesting that comets were some sort of “imitation planets.”

 

The modern debate on the nature of comets and whether they were sub- or supralunar began in the fifteenth century with Toscanelli (1397–1482), who tried to track the path of Comet Halley in 1456, as if it were a supralunar object. The debate continued in the work of Georg von Peuerbach (1423–1461), Toscanelli’s one time student, and Peuerbach’s student, Regiomontanus (1436–1476), who wrote a work on how to detect parallax in a moving comet. The debate continued in the 1530’s with many leading European astronomers taking part, including, Johannes Schöner (1477–1547), who published Regiomontanus’ work on comets, Peter Apian (1495–1552), after whom the law concerning comets’ tails in named, Copernicus (1473–1543), Gerolamo Cardano (1501–1576) and Jean Pena (1528–1558). The latter two both proposed a theory that comets were translucent, supralunar, bodies that focused the Sun’s rays like a lens creating the comets tail. Tycho’s comet, the great comet of 1577 was observed by astronomers all over Europe and Tycho, Michael Mästlin (1550-1631) and Thaddaeus Hagecius ab Hayek (1525–1600), three leading astronomers, all determined that comets were supralunar. Clavius accepted these results and included the fact that comets were supralunar in his Sphaera. This meant that the official view of the Catholic Church in general and the Jesuits in particular was that comets were supralunar. This view was confirmed again by astronomers throughout Europe observing Comet Halley in 1607. The was nothing courageous about Grassi’s theory of comets and in fact you would be hard put to it to find a serious European astronomer, apart from Galileo, who still adhered to Aristotelian cometary theory in 1618. In the same year Grassi’s Jesuit colleague Johann Baptist Cysat (c. 1587–1657), a student of Christoph Scheiner, became the first astronomer to observe a comet with a telescope giving the first ever description of a comet’s nucleus in his Mathemata astronomica de loco, motu, magnitudine et causis cometae qui sub finem anni 1618 et initium anni 1619 in coelo fulsit. Ingolstadt Ex Typographeo Ederiano 1619 (Ingolstadt, 1619). He followed Tycho Brahe in believing that comets orbited the sun. He also demonstrated the orbit was parabolic not circular.

Galileo, who due to ill health had not observed the comets of 1618, launched a vicious and insulting, unprovoked attack on Grassi’s publication, presenting a view of comets that was totally out of date, ignoring all of the accumulated scientific evidence from the last two centuries on the nature of comets just to put one over on the Jesuits and the supporters of Tycho’s theories. Livio does his best to defend Galileo’s disgusting behaviour but even he admits that Grassi was principally in the right and Galileo simply wrong. Livio goes as far as to claim that because comets has an elongated elliptical orbit (actually only some do) that Galileo’s claim that they travel in straight lines was more correct than Grassi’s claim that they orbit the Sun. In all other instances Livio goes out of his way to emphasise that hindsight shows that Galileo was right and his critics wrong so why the opposite tack here? Comets do orbit the Sun. Livio scrabbles around in the cesspit that is Galileo’s paper on comets looking for crumbs for which he can give Galileo credit.

Livio now criticises Grassi’s answer to Galileo’s attack because it contained sarcastic attacks on Galileo. Talk about pot calling the kettle black. He even brings up the obtuse suggestion that it was actually written by Christoph Scheiner because of his antagonism towards Galileo. This theory has a small problem; Scheiner only became antagonistic towards Galileo after Galileo had viciously insulted him in The Assayer, a publication that still lay in the future. Livio’s whole account of the affair is biased in Galileo’s favour so that it serves as a lead up to The Assayer, for the time being the last document in the dispute, because, as already mentioned, Livio sees it as the document in which Galileo established the place of mathematics in science. Livio’s account of The Assayer and its significance is more than somewhat outlandish.

With very little evidence to base this opinion upon, Galileo thought in 1623 that he knew the answer: the universe “is written in the language of mathematics.” It was this dedication to mathematics that raised Galileo above Grassi and the other scientist of his day, even when his specific arguments fell short of convincing–and even though he assigned to geometry a more important role than it seemed to deserve at the time. His opponents, he wrote, “failed to notice that to go against geometry is to deny truth in broad daylight.”

This whole paragraph contains so much that is wrong that it is difficult to know where to start.  I have already explained above that by the time Galileo wrote this infamous piece of purple prose it was widely accepted by both mathematician and natural philosophers that the future of science lay in an intensive mathematization. A process that was well under way when Galileo wrote something that was not new and sensational but a common place. A lot of contemporary scientists were dedicated to mathematics, such as Johannes Kepler, Simon Steven and Isaac Beeckman. In fact the last two both contributed at least as much to the development of mathematical physics in the seventeenth century as Galileo if not more. Unfortunately their achievements tend to get blended out on the popular level by the Galileo myth machine of which, Livio is just the latest in a long line of operators.

To raise Galileo above Grassi because of his dedication to mathematics is more than a joke; it’s grotesque. Earlier in his account of the dispute between Grassi and Galileo, Livio acknowledged that Grassi was an excellent optical physicist and an equally excellent architect both disciplines are fundamentally mathematical disciplines. He also points out that Grassi succeeded Grienberger as professor for mathematics at the Collegio Romano, who had succeeded Clavius. The chair for mathematics at the Collegio Romano was unique in European universities. Clavius had set up what we would now call an institute for advanced mathematics, a roll that both Grienberger and Grassi kept alive. This institute was dedicated to exemplifying, establishing and developing the roll of mathematics in the sciences. The Collegio Romano was quite simply the most advanced school for mathematics and its application anywhere in Europe. As far as geometry goes the standard textbook for geometry throughout most of the seventeenth century was Christoph Clavius’ Euclides Elementorum Libri XV, Rom 1574, note the date. This was not simply a new translation of Euclid’s classic but a modernised, simplified, streamlined textbook that was used extensively by both Catholic and Protestant educational establishments; the last edition was printed in 1717.

Shortly after the above passage on Galileo’s supposed revolutionary thoughts on mathematics we get the following throwaway line:

Galileo introduced the revolutionary departure from the medieval, ludicrous notion that everything worth knowing was already known.

When I read this I didn’t know whether to laugh, cry, rip my hair out (if I had any), or simply go out and throw myself off a high cliff in the face of such imbecilic drivel. I strongly suspect that any of my history of medieval science friends and colleagues will react similarly should they happen to read the above sentence. Starting at the very latest with the translation movement in the twelfth century medieval science was an evolving developing field with advances in a wide range of disciplines. The medieval scholars laid the foundations upon which Galileo built his own achievements. I would be quite happy to give Dr Livio a very long reading list of good books on medieval science to help him find a way out of his ignorance.

At the end of his chapter on The Assayer Livio warms up the old discovery of Pierto Redondi that Galileo was denounced to the Inquisition for the bits of primitive atomism contained in The Assayer. This was indeed true but the accusation was dismissed and nothing came of it, as Livio admits. Livio, however, now writes a whole paragraph about how important atomism, he actually means particle physics, is in modern physics, mentioning quarks, leptons, gage bosons etc., etc. I wonder how Livio would react if he knew that the principle source of atomism in the seventeenth century is now considered to be the German alchemist Daniel Sennert (1572–1637) reviving the theories of the thirteenth century alchemist Paul of Taranto. You remember alchemy one of those fictitious fields together with astrology that scientists sometime connected to.

Next up the Dialogo: Livio acknowledges that there were external political and social factors that affected the situation within the Vatican in the years leading up to the publication of the Dialogo. He starts with the astrological scandal. In 1630 an astrological prognostication predicting the Pope’s death was made and circulated by, to quote Livio, the abbot of Saint Praxedes in Rome. Livio then tells us, “some of Galileo’s adversaries tried to pin the blame on Galileo…” What Livio neglects to mention is that although Galileo was in this case innocent there were plausible ground for suspecting him, it was a case of guilt by association. Firstly, Galileo was known to be a practicing astrologer. Secondly, the abbot of Saint Praxedes, Orazio Morandi had been a good friend of Galileo’s since at least 1613. Thirdly, following an audience with the Pope concerning the forthcoming Dialogo in 1630, Galileo took part in a supper with Moriandi in Saint Praxedes together with Rafaello Visconti (Master of the Sacred Palace), another friend of Galileo’s, who read the manuscript of the Dialogo for Niccolò Ricardi the censor, who never actually read it, and an appraiser of the Inquisition. When Morandi was arrested for his horoscope and thrown into the Vatican’s dungeon, Visconti was also implicated and banished from the Vatican. That Galileo came under suspicion by association is hardly surprising. This was not a plot against Galileo as Livio claims.

We then have a wonderfully mangled piece of history from Livio, who write:

Unfortunately, this was not the end of the trials and tribulations Galileo had to endure for the publication of the Dialogo. Most significant of these was the sudden death on August 1, 1630, of Federico Cesi, the founder and sole source of funding for the Accademia dei Lincei. As a result the printing had to be done in Florence, outside of Riccardi’s jurisdiction. After some negotiations, it was agreed that Father Jacinto Stefani, a consultor of the Inquisition in Florence, would be in charge, but only after Riccardi approved the introduction and conclusion.

Although Cesi’s death was a serious blow to Galileo’s plans because he Cesi was supposed to finance the publication of the Dialogo, but this was not the reason why it was published in Florence and not in Rome. What actually happened is that after Galileo had returned to Florence from Rome with his manuscript the plague broke out in Florence. Restrictions on travel imposed by the authorities meant that Galileo could not return to Rome to oversee the printing and publication of his book. He requested permission from Riccardi to get the book published in Florence instead, but as already mentioned Riccardi hadn’t actually read the book intending to review the pages as they came of the printing press instead, having accepted Visconti’s recommendation. Riccardi was now in a pickle and wanted Galileo to send him a copy of the manuscript but due to the immense cost of producing such a copy, Galileo was very reluctant to do so.  Riccardi agreed to Galileo just sending the introduction and conclusion to Rome to be controlled and the rest being controlled in Florence by Stefani. Galileo and his circle of supporters now manipulated and even oppressed the two censors and played them against each other. The result was that the imprimatur was granted by Stefani under the impression that Ricarrdi had already cleared the manuscript for publication in Rome, he hadn’t, without actually controlling the text himself. Galileo had an imprimatur that had been obtained under false pretences, which meant that he didn’t actually have an imprimatur at all. All of this came out during the investigations following publication, which contributed to Galileo’s being prosecuted but did not play a role in the actual trial.

All of this, which Livio doesn’t mention at all, is important because when dealing with the trial Livio several times emphasises that the Church had given Galileo to publish the book as it was because he had not one but two imprimaturs, whereas in fact formally he didn’t have one at all.

Livio now tells us:

There is a certain sleight of hand in the title. [Dialogue Concerning the Two Chief Systems of the World, Ptolemaic and Copernican, Propounding Inconclusively in the Philosophical Reasons as Much for the One Side as for the Other] Even if one were to ignore the fact that the Aristotelian and the Ptolemaic systems were not identical, there was at least one other world system that in terms of agreement with observations was superior to the Ptolemaic: Tycho Brahe’s Hybrid system in which the planets revolved around the Sun, but the Sun itself revolved around the Earth. Galileo always regarded that system as unnecessarily complex and contrived, and he also thought that he’d found proof for the Earth’s motion through the phenomenon of the tides, so in striving to hand Copernicanism a clear victory (although formally the book was inconclusive) he probably didn’t want to confuse the issue with superfluous qualifications.

Once again so much to unpick. Livio obviously doesn’t understand that the system propagated by the Catholic Church before Copernicus was an uneasy mixture of Ptolemaic astronomy and Aristotelian cosmology, not Aristotelian astronomy, which is a whole different kettle of fish that had been revived by some in the sixteenth century and against which Clavius had fought tooth and nail. In fact he devotes much more space to refuting the Aristotelian homocentric astronomy in his Sphaera than he devotes to refuting Copernicus. The developments in astronomy since Copernicus published De revolutionibus had left Aristotelian cosmology in shreds and Clavius had been quite happy to also jettison that, so for Clavius, speak the Catholic Church, the world system was simply the Ptolemaic.

In fact Galileo’s whole title and thus his whole book is a complete sham By 1630 the two chief systems of the world were the Tychonic system and Johannes Kepler’s elliptical heliocentric system, which was regarded as separate from and as a competitor to Copernicus’ system. The Ptolemaic system had been killed off by the discovery of the phases of Venus and the plausible assumption that Mercury would also orbit the Sun as its general behaviour was identical to that of Venus; the phases of Mercury were first observed in 1639. Galileo just used Ptolemy as a fall guy for his sham Copernican victory. Copernicus’ heliocentric system had been rendered totally obsolete by Kepler’s discovery of the three laws of planetary motion, empirically based mathematical laws I would point out, which Galileo just completely ignored clinging to Copernicus’ ‘unnecessarily complex and contrived’ system of deferents and epicycles. Livio’s dismissal of the Tychonic system as ‘superfluous qualifications’ is put quite simply a joke, especially given that the Tychonic system was at the time the leading contender as the world system because of the failing evidence of terrestrial motion.

Livio without realising it now points out the central problem with the Dialogo:

The Dialogo is one of the most engaging science texts ever written. There are conflicts and drama, yes, but also philosophy, humor, cynicism, and poetic usage of language, so that the sum is much more than its parts.

All of the above is true except that as a piece of astronomy the sum is much less than its parts, which I will explain shortly. There is no doubt whatsoever that for all of his undeniably polymathic talents, Galileo’s greatest gift was as a polemicist. A friend of mine, who is a Galileo expert, calls him the first science publicist and this is a function that he carried out brilliantly. Yes, the Dialogo is a brilliant piece of literature, which is probably unequalled by any other scientific publication in the entire history of science. However, its literary brilliance appears to have blinded many of its readers to the fact that as a piece of astronomy it’s total crap.

As already mention, Galileo struts on to the stage to discuss what he calls the two chief world systems but actually delivers up is a sham battle between two obsolete and refuted systems. He clung stubbornly to his completely false theory that comets are mere optical illusions originating on the Earth against a mass of solid, empirical, scientific evidence that comets were in fact supralunar celestial objects that orbited the Sun. Something that Galileo was no prepared to accept because it was first proposed by Tycho, who saw it as supporting evidence for his system. He clung to Copernicus’ deferents and epicycles rather than acknowledge Kepler’s much simpler, empirically proven elliptical orbits. In fact, Galileo completely ignores Kepler’s three laws of planetary motion, by far and away, the best scientific supporting evidence for a heliocentric system because if he did acknowledge them he would have to hand the laurels for proving the superiority of the heliocentric system to Kepler instead of winning them for himself, his one and only aim in the whole story. Last but by no means least he structures his whole book and his argument around his totally ludicrous theory of the tides. One of the greatest mysteries in Galileo’s life is why he, an undeniably brilliant scientist, clung so tenaciously to such an obviously bankrupt theory.

Galileo’s masterwork sailed majestically past the actually astronomy debate in the 1630s and played little or no role in the ensuing astronomical discussion of the seventeenth century in which it was largely ignored being of no real relevance. It only became crowned as a classic in the late eighteenth and early nineteenth centuries when Galileo was declared to be a scientific martyr

Livio, like so many others, blinded by the radiance of Galileo’s rhetoric sees the matter somewhat differently. In a surprisingly short presentation of the book he praises Galileo’s achievements. There are a couple of minor points that I would like to pick up on, Livio delivers up once again the myth of heliocentricity removing the Earth from its central place in the cosmos:

More important, the act of removing humans from their central place in the cosmos was too brutal to be remedied by some philosophical pleasantries at the end of a debate from a very different tone.

The whole central place in the cosmos myth is one created in the late eighteenth century and I know of no seventeenth century use of it to criticise the heliocentric hypothesis. In a bit of waffle towards the end of this chapter Livio says the “He [Galileo] did his best…” If Galileo had truly done his best he would not have ignored the most compelling evidence for the heliocentric hypothesis, Kepler’s laws of planetary motion. He goes on to say that, “History has indeed proved that Galileo was right,” it hasn’t Galileo was wrong and Kepler was right.

Livio gives a fairly short and largely accurate account of Galileo’s trial by the Inquisition and the events leading up to following the publication of the book. The only major error being, as mentioned above, his insistence that the book had two imprimaturs. Livio acknowledges that the judgement of the three clerics, commissioned to read the book and determine whether Galileo taught or defended in anyway the heliocentric theory, that he had in fact done just that and thus broken the order from 1616 was correct. Although he can’t avoid a dig at Melchior Inchofer, the Jesuit under the three. This was the charge that was brought against Galileo and of which he was found guilty. He also can’t avoid turning up the emotional rhetoric, “What happened on the following day remains one of the most shameful events in our intellectual history.” Galileo deliberately and wilfully broke the law and received the standard punishment for having done so, which included abjuring. There is an old saying under criminals, if you can’t do the time don’t do the crime. Galileo was arrogant enough to think that he could put one over on the Catholic Church and get away scot-free, it turned out that he couldn’t.

We get a short, once again, rather gushing account of the Discorsi, Galileo real claim to fame but Livio rather spoils it by once again trying to claim that Galileo created modern science.

Through an ingenious combination of experimentation (for example, with inclined planes), abstraction (discovering mathematical laws), and rational generalisation (understanding that the same laws apply to all accelerated motions), Galileo established what has since become the modern approach to the study of all natural phenomena.

Although in the case of the studies presented by Galileo in the Discorsi he proved himself to be an excellent experimental scientist, all of these things had been done by others before Galileo and independently by others contemporaneously to Galileo. He was only one amongst other who helped to establish this methodology. Galileo was part of the evolution of a new scientific methodology that had started long before he was born and which he did not initiate. Like many others before him Livio also falsely attributes Newton’s first law, the principle of inertia, to Galileo. Whilst Galileo did indeed produce a version of the principle of inertia, Newton took his first law from the works of René Descartes, who in turn had taken it from Isaac Beeckman, who had formulated it independently of Galileo.

The next chapter of Livio’s book is an obtuse story of an account of the Galileo affair commissioned by the Vatican in the 1940s and then not published but then published under the name of a different author in the 1960s. The sole aim of this chapter is simply to take another gratuitous swing at the Catholic Church. The book closes with a fairly long digression on Einstein’s views on science and religion, which brings us to a major problem with the book, apart from the historical inaccuracies, it tries to be too many things at once.

One thing that I have mentioned in passing is Livio’s attempts to draw parallels between what happened to Galileo and the current crop of science deniers. The analogies simply don’t work because no matter how hard Livio tries to claim the opposite, Galileo’s critics in astronomy, especially the Jesuits, were not science deniers but just as much scientists as Galileo, who argued for an equally valid, in fact empirically more valid, system of astronomy, the Tychonic one, as Galileo’s heliocentric system. All the way through the book Livio keeps trying to disqualify the Tychonic system as unscientific but in the first half of the seventeenth century it was just as scientific as the heliocentric hypothesis. The only person practicing science denial here is Livio. He also wants to present the book as a discussion of the general relationship between science and religion but the whole time he argues from a presentist standpoint and refuses to view the relationship in Galileo’s time in its correct historical context. Lastly he actually wants to sell the book as a new biography of Galileo presented with the insights of a working astrophysicist, his own claim at the beginning of the book. Unfortunately it is here that he fails most.

He enters his story with a preconceived image of Galileo as a white knight on his mighty charger fighting for freedom of speech and freedom of thought in the sciences and as the originator and creator of modern experimental and mathematical science. With this image firmly in mind, from the start of his narrative, he fills out the picture with a classic case of confirmation bias. He completely ignores any real facts from the history of science that might force him to rethink his preconceived image of his hero. There is no mistaking the fact that is a strong element of hero worship in Livio’s vision of Galileo. Instead of describing the real state of science in the early seventeenth century, he present the reader with a comic book version of Aristotelian philosophy from the thirteenth century making it easier for him to present Galileo as some sort of superman, who dragged natural philosophy kicking and screaming into the modern world, whilst singlehandedly creating modern science. Edward Grant the eminent historian of medieval science (a discipline that Livio probably thinks doesn’t exist, because he seems to think that there was no medieval science), once very perceptively wrote that Aristotelian philosophy was not Aristotle’s philosophy and went on to point out that it is very difficult to define Aristotelian philosophy, as it kept on evolving and changing down the centuries. The Thomist philosophy of the Jesuits in the first third of the seventeenth century was a very different beast to the Aristotelian philosophy that Thomas Aquinas propagated in the thirteenth century. The historical distortions that Livio presents would be funny if they weren’t so grotesque.

On the question of Galileo being ‘a symbol of the fight for intellectual freedom, a lifetime of studying and thinking about Early Modern science has brought me to the conclusion that he wasn’t. In my opinion Galileo didn’t really care about such abstractions as freedom of thought, freedom of speech or intellectual freedom, all he cared about was his own vainglory. As Mario Biagioli clearly shows in his Galileo Courtier,[2] Galileo was a social climber. He was a relatively unknown, middle aged, professor of mathematics, who overnight became the most celebrated astronomer in Europe because of his telescopic discoveries. Alone the way he presented those discoveries shows his principle aim was to see what he could gain socially from them. Galileo loved his celebrity status and revelled in it. His engagement for heliocentricity was all motivated by the thought that if he could prove it true, then he would become even more famous and even more feted. To achieve this aim he lied, cheated and plagiarised. He attacked and viciously stomped on all those he regarded as competitors in his strivings for fame and adulations. He also deliberately ignored any evidence for heliocentricity presented by others (see Kepler’s laws of planetary motion) that might mean that they get the laurels and not he. Galileo might have been a great scientist but he was also a vain egoist. I think all of this might go someway to explaining his extraordinary blindness to the enormous inadequacies of his theory of the tides.

Reading this book made me very angry. The only positive thing I can say about it is that Livio is an excellent writer and the book is very well written and easy to read, but in the end even this must be viewed negatively. Mario Livio is a prominent scientist and the very successful author of popular books on mathematics and science. Because of his reputation non-specialist journals will have glowing reviews of his book, mostly written by people, who are neither Galileo experts and nor historians of science. If it follows the normal pattern for such books, specialist journals and professional historians of science will decline to review it, because it’s a pop book. The book will almost certainly become a genre bestseller and another generation of readers will acquire a mythical image of Galileo Galilei and a totally false impression of Renaissance science, something I have battled against in the eleven years that I have been writing this blog.

[1] Mario Livio, Galileo and the Science Deniers, Simon & Schuster paperbacks, New York, London, Toronto, Sydney, New Delhi, 2020

[2] Mario Biagioli, Galileo Courtier: The Practice of Science in the Culture of Absolutism, University of Chicago Press, Chicago & London, ppb. 1994

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May 27, 2020 · 8:35 am

The emergence of modern astronomy – a complex mosaic: Part XXXIV

Without any doubt the biggest impact on the discussion of astronomy and cosmology at the beginning of the seventeenth century was made by the invention of the telescope in 1608 and the subsequent discoveries that were made by astronomers with the new revolutionary instrument. That the Moon was not smooth and perfect as claimed by Aristotle but had geological features like the Earth, that the Milky Way and some nebula resolved into separate stars when viewed through the telescope, that the Sun had spots, that Jupiter had four Moons orbiting it and lastly that Venus displayed phases showing that it must orbit the Sun and not the Earth. All of these, for the times, amazing discoveries were made between the end of 1609 and 1613 then the stream of new discoveries dried up as suddenly as it had begun, why? The problem was a technological one.

All of these initial discoveries had been made using so-called Dutch or Galilean telescopes that consisted of a simple tube with two lenses a convex objective at the front and a concave eyepiece at the back.

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Optical diagram of Galilean telescope y – Distant object ; y′ – Real image from objective ; y″ – Magnified virtual image from eyepiece ; D – Entrance pupil diameter ; d – Virtual exit pupil diameter ; L1 – Objective lens ; L2 – Eyepiece lens e – Virtual exit pupil – Telescope equals Source: Wikimedia Commons

A simple instrument with a serious drawback, by adjusting the focal lengths of the lenses one can increase the magnifying power of the instrument but the greater the magnifying power the smaller the field of vision. Most of the discoveries were made using telescopes with a magnifying power of between twenty and thirty. With such telescopes, for example, Galileo could only view about one quarter of the Moon at a time. With magnifying powers above thirty the Dutch telescope becomes effectively useless as an astronomical instrument. The discoveries that had been made by 1613 marked the limit of discoveries that could be made with the simple Dutch telescope, another instrument had to be found if new discoveries were to be made.

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Galileo’s sketches of the Moon from Sidereus Nuncius. Source: Wikimedia Commons

The solution to the problem had already been presented by Johannes Kepler in his Dioptrice published in 1611.

In this important contribution to the science of optics Kepler not only explained, for the first time, how the Dutch telescope functioned but also what became known as the Keplerian or astronomical telescope with a convex objective and a convex eyepiece. He also described the function of the so-called terrestrial telescope with three convex lenses. The astronomical telescope had a much bigger field of view than the Dutch telescope and could thus be constructed with a much higher magnification.

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Source: Wikimedia Commons

It, however, suffered from the problem that whereas the image in the Dutch telescope was upright, in the astronomical telescope it was inverted. Thus the terrestrial telescope the third lens functioning as an inverter, righting the image.

Christoph Scheiner constructed astronomical telescopes for his work observing the Sun.

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Scheiner’s astronomical telescope for recording sunspots Source: Wikimedia Commons

However, Scheiner remained an exception, if a prominent one, and in general it took three decades before other astronomers turned from the Dutch telescope to telescopes with convex lenses. This of course raises the question, why? The inverted image in the simple two lens astronomical telescope was one problem, however not for Scheiner, who projected the Sun’s image onto a sheet of paper and could thus simply invert his drawn image when finished. There is, however another reason for the very protracted move away from the Dutch telescope to the astronomical telescope and that reason bears the name Galileo Galilei.

Since the publication of his Sidereus Nuncius in 1610, Galileo had become the authority for all things connected with telescopic astronomy.

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Title page of Sidereus nuncius, 1610, by Galileo Galilei (1564-1642). *IC6.G1333.610s, Houghton Library, Harvard University Source: Wikimedia Commons

Galileo was also arrogant enough to reject anything that he didn’t discover or originate. He made rude noises about the astronomical telescope praising the advantages of the Dutch telescope against the astronomical telescope, even though they didn’t exist. He was also very rude about and dismissive of Kepler’s Dioptrice claiming that it was unreadable. His authority was sufficient to hinder the adoption of the astronomical telescope.

One of the first to go against the authority of Galileo and construct and observe with an astronomical telescope was the Italian astronomer Francesco Fontana (c. 1558–1656), who as we saw earlier made the telescope with which Zupi first observed the phases of Mercury.

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Fontana drew a new more accurate map of the Moon, discovered the bands visible on Jupiter. He made the first drawings of Mars and discovered its rotation also inferring the rotation of both Jupiter and Saturn. He published a book of all of his discoveries Novae coelestium terrestriumque rerum observationes, et fortasse hactenus non vulgatae  in 1646.

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Italian astronomer Francesco Fontana created woodcuts showing the Moon and the planets as he saw them through a self-constructed telescope. In 1646, he published most of them in the book Novae Coelestium, Terrestriumque Rerum Observationes, et Fortasse Hactenus Non Vulgatae. Source

This turned out to be a major problem as the book also contained discoveries that Fontana claimed to have made, for example new moons of Jupiter Saturn and Venues, which simply didn’t exist. The charitable explanation is that these were optical artefacts produced by his telescope. This highlights another major problem of early telescopic astronomy, the quality of the early telescopes ranged from bad to abysmal.

The quality of the glass used to make the lenses was usually fairly poor. Often discoloured and equally often containing inclusions, bubbles created during the cooling of the glass, which interfered with the optical quality of the glass. All the early lenses were spherical, i.e. their curvature was segment of the surface of a sphere. This was the only shape that could be ground and polished with the technology available at the time. Even so, the further one got from the centre of a lens the more it tended to deviate from the correct form. This meant that the image formed by such lenses tended to be fairly severely distorted. The current theory is that the invention of the telescope occurred not when somebody succeeded in grinding and polishing lenses, spectacle makers had been doing that for three hundred years before the telescope emerged, or when somebody came up with the right combination of lenses, there is evidence that the magnifying property of the combination of a convex and a concave lens was known sometime before the breakthrough, but when somebody (Hans Lipperhey?) first came up with the idea of masking the outer edges of the objective lens reducing the available area to the truly spherical centre and thus creating a sharp image at the cost of a loss of light. Another problem was so-called spherical aberration. A spherical lens doesn’t actually focus light to a single point but the image is spread out over a small area causing it to blur. This was already known to Ibn al-Haytham (c. 965–c. 1040), who also knew the solution, lenses shaped according to the surfaces of ellipsoids or hyperboloids but lens makers in the seventeenth century were incapable of grinding such shapes. A much bigger problem was chromatic aberration. This is caused by the fact that simple lenses focus different wavelengths and thus different colours of light at slightly different points, causing coloured fringes on the images.  However, the discovery of chromatic aberration by Isaac Newton still lay in the future and its solution even further in the future. Over time the telescope makers discovered that making objective lenses with very long focal lengths reduced the problem of spherical and chromatic aberration and so throughout the seventeenth century the telescopes got longer and longer. Given all of these optical problems it is not surprising that astronomers made discoveries that were illusions; it is to a certain extent a wonder that they discovered anything at all.

The major breakthrough in the use of the astronomical telescope came with the invention of the multiple lens eyepiece by Anton Maria Schyrleus de Rheita, born Johann Burkhard Schyri  (1604–1660), an Capuchin monk, who had studied optics and astronomy at the University of Ingolstadt, the university of Christoph Scheiner and Johann Baptist Cysat, which, although they were no longer present when he studied there, still maintained a high standard in these disciplines. Schyri built his own telescopes and made astronomical observations. In 1643 he published his observations in his Novem stellae, which was full of new discoveries but like those of Fontana they mostly weren’t. Much more important was the publication in 1645 of his Oculus Enoch et Eliae in which he describe, without illustrations, a terrestrial telescope with a three lens eyepiece, as well a description of a pair of binoculars.

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Beginning in 1643 he had already begun to manufacture his new telescope together with the Augsburger instrument maker and optician Johann Wiesel (1583–1662), Germany’s first commercial telescope maker.

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Johann Wiesel with one of his telescopes. Copper engraving by Bartholomäus Kilian, 1660 Source: Wikimedia Commons

The Wiesel/ Schyri terrestrial telescope, which had an upright image, a wide field of vision and high-level magnification, was a huge success throughout Europe. Not only did they sell well but they were soon copied and used not just on land but also as astronomical instruments. In his book Schyri also coined the terms ocular and objective for telescopes.

The Wiesel/ Schyri telescope broke the dam and opened the market for convex lens, astronomical telescopes. In Italy Eustachio Divini (1610–1685) a clockmaker began to manufacture optical instruments becoming by 1646 the leading optician in Italy selling astronomical telescopes throughout Europe.

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Portrait of Eustachio Divini in Carlo Antonio Manzini’s “Dioptrica Pratica” Bologna 1660 Source: Wikimedia Commons

In 1649 he published his first book of observations centred round a spectacular selenography.

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Eustachio Divini Selenography

He would later go on to make detailed observations of Jupiter, the changing shape of the belts, the big red spot and the shadows cast by the satellites. His observation confirmed the axial rotation of the planet.

Divini’s reputation as Europe’s leading telescope maker/astronomer was usurped in 1656 by the still young Dutch polymath Christiaan Huygens (1629–1695), who designed his own astronomical telescope, which he constructed with his brother Constantijn (1628–1697) and with which he discovered Titan the largest of Saturn’s moons.

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Christiaan Huygens by Caspar Netscher, 1671, Museum Boerhaave, Leiden Source: Wikimedia Commons

The year before he had already staked his territory by explaining that the strange observations made by various astronomers of Saturn were in fact differing views of rings surrounding the planet. He explained this in his Systema Saturnium in 1659, which also contained the first telescopic sketches of the Orion Nebula. His explanation of the rings led to a major dispute with Divini, who was convinced that they were a belt of satellites.

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Huygens’ explanation for the aspects of Saturn, Systema Saturnium, 1659 Source: Wikimedia Commons

In the same year he made the first observations of a surface feature of another planet, Syrtis Major, a volcanic plain on Mars, using it to determine the length of the Martian day.

Divini lost his status as Italy’s prime telescope maker to the Campani brothers Matteo (1620–after 1678) and Giuseppe (1635–1715) in a series of contests staged the Accademia del Cimento to test the quality of their telescopes in 1664, which the Campani brothers won, although largely through skulduggery. Of interest is that the quality of the telescopes were compared by reading printed letters though them, a forerunner of the letter charts in the practice of every ophthalmic optician.

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Giuseppe Campani (1635-1715) Telescope with four tubes, Rome, 1666 Florence, Istituto e Museo di Storia della Scienza, inv. 2556

Although Giuseppe Campani was an active astronomer, who made his own observations and discoveries it is their most famous customer, who made the biggest impact, Giovanni Domenico Cassini (1625–1712), who became Jean-Dominique when he moved to France in 1669.

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Giovanni Cassini artist unknown Source: Wikimedia Commons

Employed as an astronomer at the observatory in Panzano by the Marquis Cornelio Malvasia (1603–1664) from 1648, Cassini was able to study under Giovanni Battista Riccioli (1598–1671) and Francesco Maria Grimaldi (1618–1663), themselves important telescopic astronomers, who produced an important lunar map, at the University of Bologna.

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Riccioli/Grimaldi Lunar Map Source: Wikimedia Commons

In 1650 he was appointed professor for astronomy at the university. During his time in Bologna Cassini was able, with the assistance of Riccioli and Grimaldi, using a meridian line in the San Petronio Basilica to prove that that either the Sun’s orbit around the Earth or the Earth’s orbit around the Sun was an ellipse thus confirming a part of Kepler’s astronomical system. The experiment was unable to determine if the system was geo-heliocentric or heliocentric.

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San Petronio Basilica The winter solstice end of the meridian line Source: Wikimedia Commons

As Europe’s leading telescopic astronomer Cassini discovered and published surface markings on Mars, determined the rotation periods of Mars and Jupiter, discovered four satellites of Saturn–Iapetus and Rhea in 1671 and 1672 followed by Tethys and Dione in 1684–he is also credited with the co-discovery with Robert Hooke of the big red spot on Jupiter. He was able to determine the orbits of the moons of Jupiter with enough accuracy that they could be used as a clock to determine longitude, as originally suggested by Galileo. A spin off of this research was the determination of the speed of light by Cassini’s assistant, Ole Rømer (1644–1710). He also showed that both the moons of Jupiter and Saturn obeyed Kepler’s third law, a fact used later by Newton in his Principia Mathematica.

The problem of aberration and the semi-solution of having objectives with ever-longer focal lengths led to the development of the aerial telescope. These are extremely long focal length telescopes that have an objective lens and an eyepiece but no tube, instead having some mechanism to keep the two lens units aligned. Christiaan Huygens constructed one with a cord between the objective and the ocular.

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An engraving of Huygens’s 210-foot aerial telescope showing the eyepiece and objective mounts and connecting string. Source: Wikimedia Commons

The most famous aerial telescope, however, was that of Johannes Hevelius (1611–1687), a wealthy beer brewer and amateur astronomer who lived in Danzig.

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Johannes Hevelius and his wife Elizabeth observing together Source: Wikimedia Commons

Hevelius constructed a telescope with a focal length of 150 feet, which became a tourist attraction.

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1673 engraved illustration of Johannes Hevelius’s 8 inch telescope with an open work wood and wire “tube” that had a focal length of 150 feet to limit chromatic aberration. Source: Wikimedia Commons

He also built a fully equipped observatory on the roof of his brewery and undertook extensive astronomical observations. He, like other, produced a very detailed map of the Moon, discovered four comets and hypothesised that comets obit the Sun on parabolic orbits, created an extensive star atlas in which he described and named ten new constellations, seven of which are still included in official star maps.

With the exception of the discovery of the five largest moons of Saturn, this second wave of seventeenth century telescopic astronomy, starting in about 1640 and continuing till the end of the century, was not as spectacular as the first one. However by the end of the century the small discoveries had accumulated to create a completely different picture of the heavens to the one that existed at the beginning. Planets were no longer Aristotle’s perfectly smooth, spherical bodies but had satellites and surface features, rotated on their axes and had determinable day lengths. The Moon had been accurately mapped by several independent astronomers and there was absolutely no doubt in the minds of the observers that it was fundamentally earth like. The position of many more stars had been accurately mapped and the orbits of the newly discovered satellites had been accurately determined. The celestial spheres of Aristotle and Ptolemaeus had been totally banished. During this second wave of telescopic observation and discovery telescopic astronomy came of age and became a recognised scientific discipline.

In 1669 Cassini was appointed the first director of the Paris Observatory, which had been founded in 1667 by the French minister of finance, Jean-Baptiste Colbert (1619–1683).

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An engraving of The Paris Observatory in the beginning of the 18th century with the wooden “Marly Tower” on the right, erected by Cassini to support both tubed and aerial very long telescopes Source: Wikimedia Commons

The founding of the Paris observatory was followed in 1675 with the founding in England of the Royal Observatory in Greenwich by Charles II, with John Flamsteed appointed in the same year as the first Astronomer Royal.

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Royal Observatory Greenwich Source: Wikimedia Commons

Berlin came somewhat later in 1700 with the appointment of Gottfried Kirch (1639–1710) but who never lived to see his observatory, which first opened in 1711. What we see here is a radical change in the status of astronomy. Whereas for most of the seventeenth century astronomy had been the province of either private citizens or university professors it now became the province of governments with astronomers appointed as civil servants required to deliver astronomical data for cartographical and navigational purposes.

 

 

 

 

 

 

 

 

 

 

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Filed under History of Astronomy, History of Optics, History of science

Annus mythologicus

Almost inevitably Newton’s so-called Annus mirabilis has become a social media meme during the current pandemic and the resulting quarantine. Not surprisingly Neil deGrasse Tyson has once again led the charge with the following on Twitter:

When Isaac Newton stayed at home to avoid the 1665 plague, he discovered the laws of gravity, optics, and he invented calculus.

Unfortunately for NdGT and all the others, who have followed his lead in posting variants, both positive and negative, the Annus mirabilis is actually a myth. So let us briefly examine what actually took place and what Isaac actually achieved in the 1660s.

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Portrait of Newton at 46 by Godfrey Kneller, 1689 Source: Wikimedia Commons

We will start with the calculus, which he didn’t actually invent at all, neither in the 1660s nor at any other time. Calculus has a more than two thousand year history stretching back to fourth century BCE. The development of calculus accelerated in the seventeenth century beginning with Kepler and Cavalieri and, previous to Newton, reaching a high point in the work of John Wallis. What Newton, like Leibniz, did was to collate, order and expand the work that others had already produced. Let us take a closer look at what Newton actually achieved in the 1660s.

But before we start, one point that various people have made on the Internet is that during this time Newton was a completely free agent with no commitments, obligations or burdens, a bachelor without children. In college his chambers were cleaned by servants and his meals were prepared by others. At home in Woolsthorpe all of his needs were also met by servants. He could and did devote himself to studying without any interruptions.

Newton, who entered Trinity College Cambridge in June 1661, was an indifferent student apparently bored by the traditional curriculum he was supposed to learn. In April 1664 he was due to take a scholarship exam, which would make him financially independent. The general opinion was not positive, however he did pass as he also passed his BA in the following year, when the prognosis was equally negative. Westfall suggests that he had a patron, who recommended that Cambridge retain him.

Freed by the scholarship, Newton now discovered his love and aptitude for the modern mathematics and set off on a two-year intensive study of the subject, almost to the exclusion of everything else, using the books of the leading mathematicians of the period, Descartes (but in the expanded, improved Latin edition of van Schooten), Viète and Wallis. In October 1666 Newton’s total immersion in mathematics stopped as suddenly as it had begun when he wrote a manuscript summarising all that he had internalised. He had thoroughly learnt all of the work available on the modern analytical mathematics, extended it and systematised it. This was an extraordinary achievement by any standards and, although nobody knew about it at the time, established Newton as one of the leading mathematicians in Europe. Although quite amazing, the manuscript from 1666 is still a long way from being the calculus that we know today or even the calculus that was known, say in 1700.

It should be noted that this intense burst of mathematical activity by the young Newton had absolutely nothing to do with the plague or his being quarantined/isolated because of it. It is an amusing fact that Newton was stimulated to investigate and learn mathematics, according to his own account, because he bought a book on astrology at Sturbridge Fair and couldn’t understand it. Unlike many of his contemporaries, Newton does not appear to have believed in astrology but he learnt his astronomy from the books of Vincent Wing (1619–1668) and Thomas Street (1621–1689) both of whom were practicing astrologers.

I said above that Newton devoted himself to mathematics almost to the exclusion of everything else in this period. However, at the beginning he started a notebook in which he listed topics in natural philosophy that he would be interested in investigating further in the future. Having abandoned mathematics he now turned to one of those topics, motion and space. Once again he was guided in his studies by the leaders in the field, once again Descartes, then Christiaan Huygens and also Galileo in the English translation by Thomas Salusbury, which appeared in 1665. Newton’s early work in this field was largely based on the principle of inertia that he took from Descartes and Descartes’ theories of impact. Once again Newton made very good progress, correcting Descartes errors and demonstrating that Galileo’s value for ‘g’ the force of acceleration due to gravity was seriously wrong. He also made his first attempt to show that the force that causes an object to fall to the ground, possibly the legendary apple, and the force that prevents the Moon from shooting off at a tangent, as the principle of inertia says it should, were one and the same. This attempt sort of failed because the data available to Newton at the time was not accurate enough. Newton abandoned this line of thinking and only returned to it almost twenty years later.

Once again, the progress that the young Newton made in this area were quite impressive but his efforts were very distant from his proof of the law of gravity and its consequences that he would deliver in the Principia, twenty year later. For the record Newton didn’t discover the law of gravity he proved it, there is an important difference between the two. Of note in this early work on mechanics is that Newton’s concepts of mass and motions were both defective. Also of note is that to carry out his gravity comparison Newton used Kepler’s third law of planetary motion to determine the force holding the Moon in its orbit and not the law of gravity. The key result presented in Principia is Newton’s brilliant proof that Kepler’s third law and the law of gravity are in fact mathematically equivalent.

The third area to which Newton invested significant time and effort in the 1660s was optics. I must confess that I have absolutely no idea what Neil deGrasse Tyson means when he writes that Newton discovered the laws of optics. By the time Newton entered the field, the science of optics was already two thousand years old and various researchers including Euclid, Ptolemaeus, Ibn al-Haytham, Kepler, Snel, and Descartes had all contributed substantially to its laws. In the 1660s Newton entered a highly developed field of scientific investigation. He stated quite correctly that he investigated the phenomenon of colour. Once again his starting point was the work of others, who were the leaders in the field, most notably Descartes and Hooke. It should be clear by now that in his early development Newton’s debt to the works of Descartes was immense, something he tried to deny in later life. What we have here is the programme of experiments into light that Newton carried out and which formed the basis of his very first scientific paper published in 1672. This paper famously established that white light is made up of coloured light. Also of significance Newton was the first to discover chromatic aberration, the fact that spherical lenses don’t sharply focus light to a single point but break it up into a spectrum, which means the images have coloured fringes. This discovery led Newton to develop his reflecting telescope, which avoids the problem of chromatic aberration.

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Newton’s sketch of his crucial experiment. Source: Royal Society

Here trying to establish a time line of when and where he carried out these experiments is very difficult, not alone because Newton’s own statements on the subject are contradictory and some of them are provably false. For example he talks about acquiring a second prism from Sturbridge Fair in a year when one didn’t take place. Also Newton’s source of light was sunlight let into a darkened room through small hole in the shutters. This was only possible at certain times of year and certain times of day when the sun is in the right position respective the window. Newton claims experiments made at times where these conditions weren’t met. That not all the experiments were made in Woolsthorpe Manor is clear, as many of them required two operators, which means that they were made when Newton was back in his chambers in Trinity College. The best guestimate is that this programme of experiments took place over the period 1660 to 1670, so once again not in Newton’s year of quarantine.

Another thing that keeps getting mentioned in connection with this story is that during his experiments on light Newton, shock-horror, stuck a pin in his eye! He didn’t. What he did was to insert a bodkin, a flat, blunt, threading needle, into his eye-socket between his skull and his eyeball in order to apply pressure to the back of his eyeball. Nasty enough, but somewhat different to sticking a pin in his eye.

All in all the developments that the young Newton achieved in mathematics and physics in the 1660s were actually spread out over a period of six years. They were also not as extensive or revolutionary as implied in Neil deGrasse Tyson brief tweeted claim. In fact a period of six intensive years of study would be quite normal for a talented student to acquire the basics of mathematics and physics. And I think we can all agree that Newton was very talented. His achievements were remarkable but not sensational.

It is justified to ask where then does the myth of the Annus Mirabilis actually come from? The answer is Newton himself. In later life he claimed that he had done all these things in that one-year, the fictional ones rather than the real achievements. So why did he claim this? One reason, a charitable interpretation, is that of an old man just telescoping the memories of his youth. However, there is a less charitable but probably more truthful explanation. Newton became in his life embroiled in several priority disputes with other natural philosophers over his discoveries, with Leibniz over the calculus, with Hooke over gravity and with Hook and Huygens over optics. By pushing back into the distant past some of his major discoveries he can, at least to his own satisfaction, firmly establish his priority.

The whole thing is best summarised by Westfall in his Newton biography Never at Rest at the end of his chapter on the topic, interestingly entitled Anni mirabiles, amazing years, not Annus mirabilis the amazing year, on which the brief summary above is largely based. It is worth quoting Westfall’s summary in full:

On close examination, the anni mirabiles turn out to be less miraculous than the annus mirabilis of Newtonian myth. When 1660 closed, Newton was not in command of the results that have made his reputation deathless, not in mathematics, not in mechanics, not in optics. What he had done in all three was to lay foundations, some more extensive than others, on which he could build with assurance, but nothing was complete at the end of 1666, and most were not even close to complete. Far from diminishing Newton’s stature, such a judgement enhances it by treating his achievements as a human drama of toil and struggle rather than a tale of divine revelation. “I keep the subject constantly before me, “ he said, “and wait ‘till the first dawnings open slowly, by little and little, into full and clear light.” In 1666 by dint of keeping subjects constantly before him, he saw the first dawnings open slowly. Years of thinking on them continuously had yet to pass before he gazed on a full and clear light.[1]

Neil deGrasse Tyson has form when it comes to making grand false statements about #histSTM, this is by no means the first time that he has spread the myth of Newton’s Annus mirabilis. What is perhaps even worse is that when historians point out, with evidence, that he is spouting crap he doesn’t accept that he is wrong but invents new crap to justify his original crap. Once he tweeted the classic piece of fake history that people in the Middle Ages believed the world was flat. As a whole series of historians pointed out to him that European culture had known since antiquity that that the world was a sphere, he invented a completely new piece of fake history and said, yes the people in antiquity had known it but it had been forgotten in the Middle Ages. He is simply never prepared to admit that he is wrong. I could bring other examples such as my exchange with him on the superstition of wishing on a star that you can read here but this post is long enough already.

Bizarrely Neil deGrasse Tyson has the correct answer to his behaviour when it comes to #histSTM, of which he is so ignorant. He offers an online course on the scientific method, always ready and willing to turn his notoriety into a chance to make a quick buck, and has an advertising video on Youtube for it that begins thus:

One of the great challenges in this world is knowing enough about a subject to think you’re right but not enough about the subject to know you’re wrong.

This perfectly encapsulates Neil deGrasse Tyson position on #histSTM!

If you want a shorter, better written, more succinct version of the same story then Tom Levenson has one for you in The New Yorker 

[1] Ricard S. Westfall, Never at Rest: A Biography of Isaac Newton, CUP; Cambridge, ppb. 1983, p. 174.

 

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Stylish writing is not necessarily good science

I have become somewhat infamous for writing #histSTM blog posts that are a predominately negative take on the scientific achievements of Galileo Galilei. In fact I think I probably made my breakthrough as a #histsci blogger with my notorious Extracting the Stopper post, deflating Galileo’s popular reputation. I actually got commissioned to write a toned down version of that post for AEON several years later. In my opinion Galileo was an important figure in the evolution of science during the early seventeenth century but his reputation has been blown up out of all proportion, well beyond his actual contributions. To make a simple comparison, in the same period of time the contributions of Johannes Kepler were immensely greater and more significant than those made by Galileo but whereas Galileo is regarded as one of the giants of modern science and is probably one of the three most well known historical practitioners of the mathematical sciences, alongside Newton and Einstein, Kepler is at best an also ran, whose popular image is not even a fraction of that of Galileo’s. This of course raises the question, why? What does/did Galileo have that Kepler didn’t? I think the answer lies in Galileo’s undeniable talents as a writer.

Galileo was a master stylist, a brilliant polemicist and science communicator, whose major works are still a stimulating pleasure to read. If you ask people about Galileo they will more often than not quote one of his well-known turns of phrase rather than his scientific achievements. The two books trope with its ‘mathematics is the language of nature’, which in the original actually reads: Philosophy is written in this grand book, which stands continually open before our eyes (I say the ‘Universe’), but can not be understood without first learning to comprehend the language and know the characters as it is written. It is written in mathematical language, and its characters are triangles, circles and other geometric figures, without which it is impossible to humanly understand a word; without these one is wandering in a dark labyrinth. Or the much-loved, the Bible shows the way to go to heaven, not the way the heavens go, which again in the original reads: The intention of the Holy Ghost is to teach us how one goes to heaven, not how heaven goes. It is a trivial truth that Galileo had a way with words.

This cannot be said of Johannes Kepler. I shall probably bring the wrath of a horde of Kepler scholars on my head for saying this but even in translation, Johannes Kepler is anything but an easy read. Galileo even commented on this. When confronted with Kepler’s Dioptrice (1611), one of the most important books on optics ever written, Galileo complained that it was turgid and unreadable. Having ploughed my way through it in German translation, I sympathise with Galileo’s negative judgement. However, in his rejection Galileo failed to realise just how scientifically important the Dioptrice actually was. Nobody in their right mind would describe Kepler as a master stylist or a brilliant polemicist.

I think this contrast in literary abilities goes a long way to explaining the very different popular conceptions of the two men. People read Galileo’s major works or selections from them and are stimulated and impressed by his literary mastery, whereas Kepler’s major works are not even presented, as something to be read by anyone, who is not a historian of science. One just gets his three laws of planetary motion served up in modern guise, as a horribly mathematical side product of heliocentricity.

Of course, a serious factor in their respective notorieties is Galileo’s infamous trial by the Roman Inquisition. This was used to style him as a martyr for science, a process that only really began at the end of the eighteenth and beginning of the nineteenth centuries. Kepler’s life, which in many ways was far more spectacular and far more tragic than Galileo’s doesn’t have such a singular defining moment in it.

Returning to the literary theme I think that what has happened is that non-scientists and non-historians of science have read Galileo and impressed by his literary abilities, his skill at turning a phrase, his adroit, and oft deceitful, presentation of pro and contra arguments often fail to notice that they are being sold a pup. As I tried to make clear in the last episode of my continuing ‘the emergence of modern astronomy’ series although Galileo’s Dialogo has an awesome reputation in Early Modern history, its scientific value is, to put it mildly, negligible. To say this appears to most people as some form of sacrilege, “but the Dialogo is an important defence of science against the forces of religious ignorance” or some such they would splutter. But in reality it isn’t, as I hope I made clear the work contributed nothing new to the on going debate and all that Galileo succeeded in doing was getting up the Pope’s nose.

The same can be said of Il Saggiatore, another highly praised work of literature. As I commented in another post the, oft quoted line on mathematics, which had led to Galileo being praised as the man, who, apparently single handed, mathematized the physical science was actually, when he wrote it, old hat and others had been writing the book of nature in the language of mathematics for at least one hundred years before Galileo put pen to paper but none of them had taken the time to express what they were doing poetically. In fact it took historians of science a long time to correct this mistaken perception, as they also tended to suffer from a serious dose of Galileo adoration. The core of Il Saggiatore is as I have explained elsewhere is total rubbish, as Galileo is arguing against the scientific knowledge of his time with very spurious assertions merely so that he doesn’t have to acknowledge that Grassi is right and he is wrong. An admission that very few Galileo scholars are prepared to make in public, it might tarnish his reputation.

Interestingly one work that deserves its historical reputation Galileo’s Sidereus Nuncius, also suffers from serious scientific deficits that tend to get overlooked. Written and published in haste to avoid getting beaten to the punch by a potential, unknown rival the book actually reads more like an extended press release that a work of science. It might well be that Galileo intended to write a more scientific evaluation of his telescopic observations and discoveries once he had established his priority but somehow, having become something of a scientific superstar overnight, he never quite got round to it. This is once again a failing that most readers tend to overlook, over awed by the very impressive literary presentation.

Much of Galileo’s written work is actually more appearance than substance, or as the Germans say Mehr Schein als Sein, but ironically, there is one major work of Galileo’s that is both literarily brilliant and scientifically solid but which tends to get mostly overlooked, his Discorsi. The experiments on which part of it is based get described by the book itself remains for most people largely unknown. I shall be taking a closer look at it in a later post.

 

 

 

 

 

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The Royal Society really needs to work on its history of the telescope

One would think that the Royal Society being one of the eldest, but not the eldest as they like to claim, scientific societies in Europe when presenting themselves as purveyors of the history of science, would take the trouble to get their facts right. If, however, one thought this, one would be wrong. Last week on the Internet the Royal Society was pushing a slide show, under their own name, on Google Arts and Culture on the history of the telescope in astronomy that in terms of historical accuracy is less than one, as a historian of science, nay of the telescope, might hope or indeed wish for.

The slide show in question is titled, Silent Harmony: astronomy at the Royal Society: Discover how innovation in telescopes and other optical instruments changed the way we see the universe. Following the title slide we have another general blurb slide but things then get serious on the history level, we get told under the heading, The new astronomy:

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Galileo Portrait by Ottavio Leoni Source: Wikimedia Commons

Galileo Galilei (1564-1642) was the first to explore the solar system using a telescope. His work directly built on famous predecessors such as Nicolaus Copernicus (1473-1543) and Johannes Kepler (1571-1630), who set out to model a heliocentric universe – one in which the sun is at the centre of the universe – and theorise the motion of planets. 

Sometimes I tire slightly of repeating myself but once more into the breach dear friends, once more. Galileo was not the first to explore the solar system using a telescope. That honour goes to a man in London, you know London home of the Royal Society, Thomas Harriot (1560–1621).

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Portrait often claimed to be Thomas Harriot (1602), which hangs in Oriel College, Oxford. Source: Wikimedia Commons

Also at the same time as Galileo was aiming his telescope at the heavens in Padua, Simon Marius (1573–1625) was doing the same in Ansbach in Franconia

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Simon Marius Source: Wikimedia Commons

and Giovanni Paolo Lembo (1570–1618) and Odo van Maelcote (1572–1615) in Rome. Whilst Galileo was more than prepared to call himself a Copernican, he very strongly rejected or ignored the work of Johannes Kepler, so saying that his work directly built on that of Kepler is more than a simple distortion of history. To say that these three theorised the motion of planets is to say the least bizarre, all astronomical models whether heliocentric, geocentric or geo-heliocentric theorise the motion of planets that is a large part of what astronomy is. We are not finished with Signor Galileo:

Galileo’s Starry Messenger was the first published work to incorporate scientific observations made using a telescope.

The treatise contains descriptions of lunar landscapes, new stars in well-known constellations and the major satellites of Jupiter.

This is all correct, however because he was the first to publish people make the mistake of thinking he was the first or even the only one to make telescopic observations in 1609. Moving on, the next slide caption isn’t correct:

Galileo designed and built the most powerful telescope of his generation.

His own instrument, a thirty-power magnifier preserved at the Museo Galileo in Florence, served as model to other instrument-makers for many years.

I’m beginning to think that the Royal Society has got something against Thomas Harriot. Whilst Galileo did indeed build a thirty-power telescope it was not the most powerful telescope of his generation, Harriot built a fifty-power one. However, as in a Dutch telescope (convex objective/concave eyepiece) the field of vision diminishes with magnification the fifty-power telescope proved next to useless. Galileo’s own instrument did not serve as a model to other instrument-makers for many years that, is to put it mildly, total bullshit. Lots of people knew how to construct a simple Dutch telescope and did so without any reference to Galileo.

We skip a few slides and arrive at the most famous President of the Royal Society, Isaac Newton;

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Portrait of Newton by Godfrey Kneller, 1689 Source: Wikimedia Commons

we get a picture of Newton’s reflecting telescope with the following caption:

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Replica of Newton’s second reflecting telescope, which he presented to the Royal Society in 1672 Source: Wikimedia Commons

The Royal Society also owns a reflecting telescope made by Newton as a direct application of his theories on light and colour.

This statement is a best misleading and at worst simply wrong depending on how you interpret it. Newton’s theories on light and colour led him to the awareness that the coloured fringes visible on the images of the then normal refracting telescope were the result of chromatic aberration, i.e. the visible light being split up into the colour spectrum when passing through a spherical lenses. This discovery led him to developing a reflecting telescope because he believed falsely that creating an achromatic lens was impossible. It would be more than half a century before Chester Moore Hall invented the first achromatic lens. The principle of the reflecting telescope, which with a suitable mirror, does not suffer from chromatic aberration, had been known since antiquity and Newton was by no means the first to try and construct one. He was, however, the first to succeed in producing a functioning reflecting telescope. You can read an outline of the full history of the reflecting telescope here. Interestingly nobody succeeded in copying Newton’s achievements for the best part of fifty years, when John Hadley (1682–1784), another fellow of the Royal Society, who gets no mention in this slide show, finally succeeded in producing large scale functioning reflecting telescopes; Newton’s instrument was little more than a toy.

The instrument allowed him to make various observations conclusive with his theories on gravity.

This caption is just high-grade rubbish. Newton did not make any observations with this instrument that were in anyway connected with his theory of gravity, let alone conclusive with it.

There are, in the mean time, quite a few good books on the history of the telescope, I have most of them sitting on my book shelf and I’m sure some of them are in the Royal Society’s library, so why didn’t who ever put this slide show together consult them or simply ask an expert?

 

 

 

 

 

 

 

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The emergence of modern astronomy – a complex mosaic: Part XX

It is not an exaggeration to say that the invention of telescope was a very major turning point in the general history of science and in particular the history of astronomy. Basic science is fundamentally empirical; people investigating the world make observations with their senses–taste, sight, touch, smell, hearing–then try to develop theories to describe and explain what has been observed and recorded. The telescope was the first ever instrument that was capable of expanding or strengthening one of those senses that of sight. The telescope made it possible to see things that had never been seen before.

The road to the telescope was a long one and one of the questions is why it wasn’t invented earlier. There are various legends or myths about devices to enable people to see things at a distance throughout antiquity and various lens shaped objects also from the distant past that might or might not have been lenses. Lenses in scientific literature in antiquity and the early middle ages were burning lenses used to focus sunlight to ignite fires. The first definite use of lenses to improve eyesight were the so-called reading stones, which emerged around 1000 CE, approximately hemispherical lenses, placed on documents to help those suffering from presbyopia, weakening of the ability of the eye to focus due to aging.

Reading-stone

Source: Zeiss

Reading glasses utilising plano-convex lenses first appeared around 1290.

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The earliest pictorial evidence for the use of eyeglasses is Tommaso da Modena’s 1352 portrait of the cardinal Hugh de Provence reading in a scriptorium Source: Wikimedia Commons

The current accepted theory of the discovery of simple lenses is that in the Middle Ages monks cutting gems to decorate reliquary discovered the simple magnifying properties of the gemstones they were grinding and polishing.

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Reliquary Cross, French, c. 1180 Source: Wikimedia Commons

By the middle of the fifteenth century eye glasses utilising both convex and concave lenses were being manufactured and traded, so why did it take until 1608 before somebody successfully combined a concave lens and convex lens to create a simple so-called Dutch telescope?

There are in fact earlier in the sixteenth century in the writings of Girolamo Fracastoro (ca. 1476–1553) and Giambattista della Porta (1532–1615) descriptions of the magnifying properties of such lens combinations but these are now thought to refer to special eyeglasses rather than telescopes.

Della Porta Telescope Sketch

The early lenses were spherical lenses, which were hand ground and polished and as a result were fairly inaccurate in their form tending to deviate from their ideal spherical form the further out one goes from the centre.  These deformations caused distortions in the images formed and combining lenses increased the level of distortion making such combinations next to useless. It is now thought that the breakthrough came through the use of a mask to stop down the diameter of the eyepiece lens cutting out the light rays from the periphery, restricting the image to the centre of the lens and thus massively reducing the distortion. So who made this discovery? Who first successfully developed a working telescope?

This question has been hotly discussed and various claims just as hotly disputed since at least the middle of the seventeenth century. However, there now exists a general consensus amongst historian of optics.

[To see the current stand on the subject read the bog post that I wrote at this time last year, which I don’t intend to repeat here]

Popular accounts of the early use of the telescope in astronomy almost always credit Galileo Galilei, at the time a relatively unknown professor for mathematics in Padua, with first recognising the potential of the telescope for astronomy; this is a myth.

As can be seen from the quote from the French newsletter AMBASSADES DV ROY DE SIAM ENVOYE’ A L’ECELence du Prince Maurice, arriué à la Haye le 10. Septemb.1608., recording the visit of the ambassador of the King of Siam (Thailand), who was also present at the first demonstration of the telescope the potential of this new instrument, as a tool for astronomy was recognised from the very beginning:

even the stars which normally are not visible for us, because of the scanty proportion and feeble sight of our eyes, can be seen with this instrument.

In fact the English polymath Thomas Harriot (1560–1621) made the earliest known telescopic, astronomical observations but, as with everything else he did, he didn’t publish, so outside of a small group of friends and acquaintances his work remained largely unknown. Also definitely contemporaneous with, if not earlier than, Galileo the Franconian court mathematicus, Simon Marius (1573–1625), began making telescopic observations in late 1609. However, unlike Galileo, who as we will see published his observations and discoveries as soon as possible, Marius didn’t publish until 1614, which would eventually bring the accusation of having plagiarised Galileo.  At the Collegio Romano, the Jesuit University in Rome, Odo van Maelcote (1572–1615) and Giovanni Paolo Lembo (1570–1618) were also making telescopic observations within the same time frame. There were almost certainly others, who didn’t make their observations public.

Before we turn to the observations and discoveries that these early telescopic observers made, we need to look at a serious technical problem that tends to get ignored by popular accounts of those discovery, how does a telescope work? In 1608 when the telescope first saw the light of day there existed absolutely no scientific explanation of how it worked. The group of early inventors almost certainly discovered its magnifying effect by accident and the first people to improve it and turn it into a viable scientific instrument, again almost certainly, did so by trial and error. At this point the problem is not to find the optical theory needed to develop better telescopes systematically but to find the optical theory necessary to justify the result the telescope produced. Using any sort of instrument in science requires a scientific explanation of how those results are achieved and as already stated at the beginning no such theory existed. The man, who came to the rescue, was Johannes Kepler in the second of his major contributions to the story of heliocentric astronomy.

Already in 1604 in his Ad Vitellionem Paralipomena Astronomiae pars optica, Kepler had published the first explanation of how lenses focus light rays and how eyeglasses work to compensate for short and long sightedness so he already had a head start on explaining how the telescope functions.

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Source

Francesco Maurolico (1494–1575) had covered much of the same ground in his Theoremata de lumine et umbra earlier than Kepler but this work was only published posthumously in 1611, so the priority goes to Kepler.

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In 1611 Kepler published his very quickly written Dioptrice, in which he covered the path of light rays through single lenses and then through lens combinations. In this extraordinary work he covers the Dutch or Galilean telescope, convex objective–concave eyepiece, the astronomical or Keplerian telescope, convex objective–convex eyepiece, the terrestrial telescope, convex objective–convex eyepiece–convex–field–lens to invert image, and finally for good measure the telephoto lens! Galileo’s response to this masterpiece in the history of geometrical optics was that it was unreadable!

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Source: Wikimedia Commons

In the next section we will turn to the discoveries that the various early telescopic astronomical observers made and the roles that those various discoveries played in the debates on, which was the correct astronomical model of the cosmos. A much more complicated affair than it is often presented.

 

 

 

 

 

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The emergence of modern astronomy – a complex mosaic: Part XIX

Tycho and Kepler was one of the most important partnerships in the history of Early Modern science and a good counter example to those who mistakenly believe in the lone genius myth. Tycho the observational astronomer with an obsession for accuracy, who produced an unequalled volume of raw data

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Tycho Brahe Source: Wikimedia Commons

and Kepler the theoretical astronomer with an equal obsession for accuracy, who would come to turn that data into a completely new heliocentric model of the cosmos.

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Johannes Kepler Source: Wikimedia Commons

Superficially a marriage made in heaven but when the two men first met in Prague their future cooperation almost ended before it even started. Arriving in February 1600 at Tycho’s new home in Benátky Castle Kepler was initially welcomed as a guest and observer.

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Benátky Castle Source: Wikimedia Commons

He was impressed by Tycho’s setup and his data collection to which he hoped to gain access to fine tune his Platonic solids model of the cosmos. Tycho was impressed by the young theoretician but, suspicious of possible plagiarism, was not prepared to make his data freely available. Kepler was of course desperate for paid employment and after two months entered negotiations with Tycho over some sort of fixed employment. The young, working class, German mathematician took umbrage at the arrogant attitude of the Danish aristocrat and in a strop broke off the talks, departing for Prague. Interestingly Tycho, needing fresh workers, proved himself surprisingly conciliatory and through the diplomatic efforts of the Bohemian physician Jan Jesenius (1566–1621) Kepler was persuaded to return to Benátky, where conditions of employment for him were eventually arranged.

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Jan Jesenius

Kepler, who had left his family in Graz, now returned there and after a failed attempt to obtain employment from Archduke Ferdinand in August 1600 he finally set off for Prague with household and family. Initially he was employed directly by Tycho his first task being to write an account of the plagiarism dispute between Tycho and Ursus, probably as a punishment for having supplied Ursus with munitions in that dispute, and naturally he was expected to find in Tycho’s favour. This work, which turned out to be very impressive, was never published in Tycho’s or Kepler’s lifetimes and much more significant was the first real astronomical work that Tycho assigned to him.

When Kepler had first arrived in Benátky, Christen Longomontanus (1562–1647), who had returned to the fold having initially left Tycho’s circus when he quit Denmark, was working on the raw data for the orbit of Mars.

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Christen Longomontanus

Tycho now removed him from this work, assigning him instead to the Moon’s orbit, and gave the task instead to Kepler under Longomontanus’ supervision. This turned out to be one of the most fateful decisions in the entire history of astronomy. Kepler initially thought that he could knock off this task in a couple of weeks but in fact it took him six years to complete but as well as the mathematical difficulties involved there were extenuating circumstances. Before turning to the results of what Kepler called his war with Mars, a play upon the fact that Mars was the Roman god of war, we need to take a look at some of those circumstances.

Tycho’s financial resources were stretched so he negotiated with Rudolf, the Emperor, for Kepler to be appointed directly to the court in order to produce a new set of planetary tables, using Tycho’s data, to replace the existing Prutenic Tables of Erasmus Reinhold and to be named, of course, after the Emperor. What seemed like a step up for Kepler proved to be very problematic, as Rudolf, always strapped for cash, was very bad at paying his staff.

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Rudolf II Portrait by Martino Rota Source: Wikimedia Commons

The next major event was the death of Tycho on 24 October1601 barely a year after Kepler had started working with him. For Kepler this was both good and bad. Already appointed to produce planetary tables for Rudolph, he now inherited Tycho’s title as Imperial Mathematicus, as the obvious candidate Longomontanus had left Benátky and Tycho’s service the previous year. This was truly a major step up but with the same caveat that Rudolf was extremely bad at paying salaries. Kepler was, of course, now in physical possession of all of Tycho’s data but unfortunately not in legal possession. Although he had been Imperial Mathematicus, Tycho’s data did not belong to Rudolf but was his own private property and was on his death inherited by his family. Kepler was faced with the problem of negotiating with Tycho’s son in law Frans Gansneb genaamd Tengnagel van de Camp over the use of the data. Frans Tengnagel initially claimed that he would work with the data but he was a diplomat and not an astronomer or mathematician and in the end a compromise was reached in that Kepler could use the data but that Fans Tengnagel would be named as co-author in any resulting publications. In fact, in the end Frans Tengnagel’s only contribution was a preface to the Astronomia nova.

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Frans Gansneb genaamd Tengnagel van de Camp

Even though he now possessed the desired data Kepler did not sit down solely to finish calculating the orbit of Mars. In 1604 he published his Astronomia Pars Optica, the most important work in optics since the Middle Ages, which laid the foundations of the modern science of optics.

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Astronomiae Pars Optica

It included the first explanations of how lenses work to correct short and long sight and above all the first-ever correct explanation of how the image is formed in the eye. This work would, as will see, proved extremely important following the invention of the telescope at the end of the decade. Also in 1604 a supernova appeared in the skies and Kepler systematically observed it, confirmed it was definitively supralunar (i.e. above the moon’s orbit) and wrote up and published his findings, De Stella nova in pede Serpentarii, in Prague in 1606. This of course confirmed what had already been demonstrated in the 1570s that the heavens were not incorruptible, driving another nail into the coffin of Aristotelian cosmology.

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Stella nova in pede Serpentarii title page

During this period Kepler also finished his determination of the orbit of Mars, in the course of which he changed the course of astronomy forever. Published in 1609 the Astronomia Nova ΑΙΤΙΟΛΟΓΗΤΟΣ seu physica coelestis, tradita commentariis de motibus stellae Martis ex observationibus G.V. Tychonis Brahe, to give it its full title, is without any doubt whatsoever one of the most important books in the whole history of astronomy, although it was not recognised as such until long after it appeared.

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Astronomia Nova title page Source: Wikimedia Commons

Unique amongst major scientific publications the book appears to outline in great detail the path that the author took in his determination of the Planet’s orbit, including all the false paths he followed, the errors that he made and even his calculating mistakes. Normally scientists leave all of this out of their published work presenting only the successful conclusions of their battles with the evidence and data. So why did Kepler include all of his six years of strife in his finished product. The answer lies in the statement above, appears to outline. In fact the account presented is to some extent, to use an actual term, fake news. Kepler is deliberately misleading his readers but why?

Kepler was a convinced Copernicaner in a period where the majority of astronomers were either against heliocentricity, mostly with good scientific reasons, or at best sitting on the fence. Kepler was truly revolutionary in another sense, he believed firmly in a physical cause for the structure of the cosmos and the movement of the planets. This was something that he had already propagated in his Mysterium Cosmographicum and for which he had been strongly criticised by his teacher Mästlin. The vast majority of astronomers still believed they were creating mathematical models to save the phenomena, irrespective of the actually physical truth of those models. The true nature of the cosmos was a question to be answered by philosophers and not astronomers. Kepler structured the rhetoric of the Astronomia Nova to make it appear that his conclusions were inevitable; he had apparently no other choice, the evidence led him inescapably to a heliocentric system with a real physical cause. Of course, he couldn’t really prove this but he did his best to con his readers into thinking he could.

Kepler tested and refined his arguments in one of the most fascinating correspondences in the history of astronomy, which took place with the Frisian amateur astronomer David Fabricius (1564–1617) over a total of eight years; a correspondence that also makes a mockery of the lone genius myth. Fabricius was a Protestant pastor and a passionate amateur astronomer. He first emerged on the European astronomical scene when he took up contact with Jost Bürgi (1552–1632) in Kassel in 1592 to request his advice on constructing astronomical instruments. In 1596 having, as the first astronomer to do so, observed the variable star Mira he wrote a letter to Tycho Brahe in Hven describing his discovery. This was the start of an extensive correspondence between the two that lasted until Tycho’s death in 1601. In that year he visited Tycho in Prague, where he met Simon Marius (1573–1625) with whom he would also correspond but not Kepler who was in Austria on family business. The letters that Kepler and Fabricius exchanged were more in the nature of academic papers often running to forty or fifty pages.

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Monument to David Fabricius & his son Johannes in the church yard in Osteel his parish Source: Wikimedia Commons

Fabricius was neither a geocentrist nor a heliocenrist but a solid supporter of Tycho’s geo-heliocentric compromise and so was an ideal sparing partner for Kepler. Kepler would outline his latest heliocentric theories and Fabricius would do his best to demolish them and his best was very good indeed. This meant that over the years of their correspondence Kepler could really develop and refine the complex arguments that he would then finally present in the Astronomia nova. Probably frustrated by his failure to convert Fabricius to his way of thinking, Kepler rather abruptly broke off the correspondence in 1609. Fabricius, who Kepler acknowledge as the best observational astronomer in Europe following Tycho’s demise, died tragically in 1617, beaten to death with a spade by a local farmer, who thought Fabricius had accused him of being a thief in a sermon.

Despite Kepler’s best efforts the Astronomia nova was largely a flop when first published. Those who read it largely rejected his argument for heliocentricity. The book however contains two of the most important discoveries in the history of astronomy, Kepler’s first two laws of planetary motion:

1) That planets orbit the Sun on elliptical paths with the Sun situated at one focus of the ellipse

2) That a line connecting the planet to the Sun sweeps out equal areas in equal periods of time.

Kepler actually developed the second law first using it as his primary tool to determine the actually orbit of Mars. The formulation of this law went through an evolution, which he elucidates in the book, before it reached its final form. The first law was in fact the capstone of his entire endeavour. He had known for sometime that the orbit was oval and had even at one point considered an elliptical form but then rejected it. When he finally proved that the orbit was actually an ellipse he knew that his battle was over and he had won.

Although, at the time, Kepler had temporarily lost the public battle in the larger war for the recognition that the cosmos, as it was then known, was indeed heliocentric the publication of the Astronomia nova represents one of the most important steps towards the final victory in that war. This would not remain Kepler’s only contribution to that war but before we look at his further efforts we need to turn to what was possibly the most important event in the history of Early Modern astronomy, the invention of the telescope.

[Attentive readers of this blog might have noticed that I have ‘plagiarised’ my own post on the Astronomia nova from December last year. I simply couldn’t be bothered to find new ways of expressing things that I had already expressed to my own satisfaction.]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Filed under History of Astronomy, History of Optics, History of science

An important 13th-century book on optics

The thirteenth-century Silesian friar and mathematician Witelo is one of those shadowy figures in the history of science, whose influence was great but about whom we know very little.

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Page from a manuscript of Perspectiva with a miniature of the author Source: Wikimedia Commons

His biography can only be pieced together from scattered comments and references. In his Perspectiva he refers to “our homeland, namely Poland” and mentions Vratizlavia (Wroclaw) and nearby Borek and Liegnitz suggesting that he was born in the area. He also refers to himself as “the son of Thuringians and Poles,” which suggests his father was descended from the Germans of Thuringia who colonized Silesia in the twelfth and thirteenth centuries and his mother was of Polish descent.

A reference to a period spent in Paris and a nighttime brawl that took place in 1253 suggests that he received his undergraduate education there and was probably born in the early 1230s. Another reference indicates that he was a student of canon law in Padua in the 1260s. His Tractatus de primaria causa penitentie et de natura demonum, written in Padua refers to him as “Witelo student of canon law.” In late 1268 or early 1269 he appears in Viterbo, the site of the papal palace. Here he met William of Moerbeke  (c. 1220–c. 1286), papal confessor and translator of philosophical and scientific works from Greek into Latin. Witelo dedicated his Perspectiva to William, which suggest a close relationship. This amounts to the sum total of knowledge about Witelo’s biography.

In the printed editions of the Perspectiva he is referred to as Vitellio or Vitello but on the manuscript copies as Witelo, which is a diminutive form of Wito or Wido a common name in thirteenth century Thuringia, so this is probably his correct name. Family names were uncommon in thirteenth-century Poland, and there is no evidence to suggest that Witelo had one.[1]

Witelo’s principle work, his Perspectiva, was not started before 1270, as he uses William of Moerbeke’ translation of Hero of Alexandria’s Catoptrica, which was only completed on 31stDecember 1269. Witelo is one of three twelfth century authors, along with Roger Bacon (c. 1219–c. 1292) and John Peckham (c. 1230–1292), who popularised and disseminated the optical theories of  Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham, known in Latin as Alhazen or Alhacen. Al-Haytham’s Kitāb al-Manāzir (Book of Optics) was the most important Islamic texts on optics and one of the most important in the whole history of optics. It was translated into Latin by an unknown translator in the late twelfth or early thirteenth century with the title De aspectibus. Bacon was the first European author to include De aspectibus in his various writings on optics and Witelo and Peckham followed his lead. Although it is clear that Witelo used Ptolemy’s Optica, Hero’s Catoptrica and the anonymous De speculis comburentibus in composing his Perspectiva, and that he was aware of Euclid’s Optica, the Pseudo-Euclid Catoptrica and other prominent works on optics, it is very obvious that his major debt is to al-Haytham’s De aspectibus, although he never mentions him by name.

The Perspectiva is a monumental work that runs to nearly five hundred pages in the printed editions. It is divided into ten books:

Book I: Provides the geometric tools necessary to carry out geometrical optics and was actually used as a geometry textbook in the medieval universities.

Book II: Covers the nature of radiation, the propagation of light and colour, and the problem of pinhole images.

Book III: Covers the physiology, psychology, and geometry of monocular and binocular vision by means of rectilinear radiation.

Book IV: Deals with twenty visible intentions other than light and colour, including size, shape, remoteness, corporeity, roughness darkness and beauty. It also deals with errors of perception.

Book V: Considers vision by reflected rays: in plane mirrors

Book VI: in convex spherical mirrors

Book VII: in convex cylindrical and conical mirrors

Book VIII: in concave spherical mirrors

Book IX: in concave cylindrical, conical, and paraboloidal mirrors

Book X: Covers vision by rays refracted at plane or spherical surfaces; it also includes a discussion of the rainbow and other meteorological phenomena.

Witelo’s Perspectiva became a standard textbook for the study of optics and, as already mentioned above, geometry in the European medieval universities; it was used and quoted extensively in university regulations right down to the seventeenth century. The first printed edition of this important optics textbook was edited by Georg Tannstetter (1482–1535) and Peter Apian (1495–1552) and printed and published by Johannes Petreius (c. 1497–1550) in Nürnberg in 1535 under the title Vitellionis Mathematici doctissimi Peri optikēs, id est de natura, ratione & proiectione radiorum visus, luminum, colorum atque formarum, quam vulgo perspectivam vocant.

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Georg Tannstetter Portrait ca. 1515, by Bernhard Strigel (1460 – 1528) Source: Wikimedia Commons

Georg Tannstetter born in Rain am Lech in Bavaria had studied at the University of Ingolstadt under Andreas Stiborius (c. 1464–1515) and when Stiborius followed Conrad Celtis (1459–1508) to Vienna in 1497 to become professor for mathematics on the newly established Collegium poetarum et mathematicorum Tannstetter accompanied him. In 1502 he in turn began to lecture on mathematics in Vienna, the start of an illustrious career.

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Conrad Celtis: Gedächtnisbild von Hans Burgkmair dem Älteren, 1507 Source: Wikimedia Commons

Peter Apian, possibly his most famous pupil, was born, Peter Bienewitz, in Leisnig. He entered the University of Vienna in 1519 graduating B.A. in 1521. He then moved first to Regensburg and then to Landshut where he began his publishing career with his Cosmographicus liber in 1524.

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Apianus on a 16th-century engraving by Theodor de Bry Source: Wikimedia Commons

Following several failed attempts to acquire the position, Apian was appointed printer to the University in Ingolstadt in 1527, as well as lecturer for mathematics, positions he would hold until his death in 1552, when he was succeeded by his son Philipp (1531–1589), who had begun to take over his teaching duties before his death.

Apian’s Ingolstadt printing office continued to produce a steady stream of academic publications, so it comes as somewhat of a surprise that he chose to farm out the printing and publication of his own Instrumentum primi mobilis (1534) and the Tannstetter/Apian edited Witelo Perspectiva (1535) to Johannes Petreius in Nürnberg. Although both books were large and complex it should have been well within Apian’s technical capabilities to print and publish them in his own printing office; in 1540 he printed and published what is almost certainly the most complex science book issued in the sixteenth century, his Astronomicon Caesareum. The problem may have been a financial one, as he consistently had problems getting the university to supply funds to cover the advance cost of printing the books that he published.

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Source: Wikimedia Commons

Johannes Petreius, actually Hans Peter, was born in the Lower Franconian village of Langendorf near Hammelburg. He studied at the university in Basel graduating MA in 1517. Here he also learnt the printing trade in the printing office of his uncle Adam Petri (1445–1527). In 1523 he moved to Nürnberg where he set up his own printing business. By the early 1530s, when Apian approached him, he was one of the leading German printer publishers with a good reputation for publishing mathematical works, although his most famous publication Copernicus’ De revolutionibus orbium coelestium still lay in the future. In fact his publishing catalogue viewed as a whole makes him certainly the most important printer publisher of mathematical books in Germany and probably in the whole of Europe in the first half of the sixteenth century. As was his style he produced handsome volumes of both Apian’s Instrumentum and Witelo’s Perspectiva.

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Apian’s Instrumentum Title Page Source: Sothebys

Although he died in 1550 the Petreius printing office would issue an unchanged second edition of the Witelo in 1551, which was obviously in preparation before his death. After his death his business ceased as he had no successor and his catalogue passed to his cousin Heinric Petri (1508–1579) in Basel.

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Vitellionis Mathematici doctissimi Peri optikēs… title page Source: Christie’s

The Witelo volume would come to play a role in the eventual publication of Copernicus’ magnum opus by Petreius. When Georg Joachim Rheticus (1514-1574) set out in 1539 to seek out Copernicus in Frombork he took with him the Witelo tome as one of six specially-bound-as-a-set books, four of which had been printed and published by Petreius, as a gift for the Ermländer astronomer. The Petreius books were almost certainly meant to demonstrate to Copernicus what Petreius would do with his book if he allowed him to print it. The mission was a success and in 1542 Rheticus returned to Nürnberg with Copernicus’ precious manuscript for Petreius to print and publish in 1543.

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Copernicus De revolutionibus title page Source: Wikimedia Commons

There was a third printed edition of Witelo’s Perspectiva printed and published from a different manuscript by Friedrich Risner (1533–1580) together with al-Haytham’s De aspectibus in a single volume in Basel in 1527 under the title, Opticae thesaurus: Alhazeni Arabis libri septem, nuncprimum editi; Eiusdem liber De Crepusculis et nubium ascensionibus, Item Vitellonis Thuringopoloni libri X.

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Friedrich Risner edition Opticae Thesaurus (Basel, 1572) Title Page Source

This is the edition that Johannes Kepler (1571–1630) referenced in his Astronomiae pars optica. Ad Vitellionem Paralipomena (The Optical Part of Astronomy: Additions to Witelo) published in Prague in 1604, the most important book on optics since al-Haytham’s.

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Astronomiae pars optica. Ad Vitellionem Paralipomena  Source: University of Reading

Witelo remains an obscure thirteenth century scholar but his optics magnum opus cast a shadow down more than four hundred years of European history of optics. [2]

[1]All of the biographical information, and much else in this article, is taken from David C. Lindberg, Witelo in Complete Dictionary of Scientific Biography, Charles Scribner’s Sons, 2008. Online at Encyclopedia.com

[2]For more on Witelo’s influence on the history of optics see David C. Lindberg, Theories of Vision from al-Kindi to Kepler, University of Chicago Press, Chicago and London, 1976, ppb. 1981.

On Peter Apian as a printer Peter Apian: Astronomie, Kosmographie and Mathematik am Beginn der Neuzeit mit Ausstellungskatalog, ed. Karl Röttel, Polygon-Verlag, Buxheim, Eichstätt, 1995 and Karl Schottenloher, Die Landshunter Buchdrucker des 16. Jahrhundert. Mit einem Anhang: Die Apianusdruckerei in Ingolstadt, Veröffentlichungen der Gutenberg-Gesellschaft XXXI, Mainz, 1930

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Filed under Early Scientific Publishing, History of Astronomy, History of Mathematics, History of Optics

Galileo’s the 12th most influential person in Western History – Really?

Somebody, who will remain nameless, drew my attention to a post on the Presidential Politics for America blog shortly before Christmas in order to provoke me. Anybody who knows me and my blogging will instantly recognise why I should feel provoked if they just read the opening paragraph.

Despite the paradigm-shifting idea of our #28 Nicolaus Copernicus, for nearly a century afterward his heliocentric theory twisted in the solar wind. It took another man to confirm Copernicus’s daring theory. That alone would make this other man an all-time great contributor to Western science, but he gifted us so much more than merely confirming someone else’s idea. He had a series of inventions, discoveries, and theories that helped modernize science. His accomplishments in mechanics were without precedent. His telescope observed what was once unobservable. Perhaps most importantly, he embodied, furthered, and inspired a growing sentiment that truth is a slave to science and facts, not authority and dogma.

This man was Galileo Galilei, and he’s the 12thmost influential person in Western History.

Before I start on my usually HistSci_Hulk demolition job to welcome the New Year I should point out that this crap was written by somebody claiming to be a history teacher; I feel for his student.

This post is part of a long-term series on The Top 30 Most Influential Western European Figures in History; I kid you not! Sorry, but I’m not a fan of rankings in general and to attempt to rank the historical influence of Western Europeans is in my opinion foolhardy at best and totally bonkers at worst.

We turn our attention to his #11 Galileo Galilei. We start with the very obvious false claim, the very first one in fact, Galileo did not ‘confirm Copernicus’s daring theory.’ Next up we have the statement: ‘He had a series of inventions, discoveries, and theories that helped modernize science.’

Only in his teens, he identified the tautochronic curve that explains why the pendulum behaves as it does. This discovery laid the groundwork for Christian [sic] Huygens to create the world’s first pendulum clock, which became the most accurate method of keeping time into the twentieth century. 

It is Christiaan not Christian Huygens. Galileo discovered the isochronal principle of the pendulum but the earliest record of his researches on the pendulum is in a letter to his patron Guidobaldo del Monte dated 2 November 1602, when he was 38 years old. The story that he discovered the principle, as a teenager was first propagated posthumously by his first biographer Viviani and to be taken with a pinch of salt. He didn’t discover that the free circular pendulum swing is not isochronal but only the tautochrone curve is; this discovery was actually made by Huygens. There is no evidence that Galileo’s design of a never realised pendulum clock had any connections with or influence on Huygens’ eventually successfully constructed pendulum clock. That pendulum clocks remained the most accurate method of keeping time into the twentieth century is simply wrong.

The precocious Galileo also invented thethermoscope…

 It is not certain that Galileo invented the thermoscope; it is thought that his friend Santorio Santorio actually invented it; he was certainly the first during the Renaissance to publish a description of it. The invention was attributed to Galileo, Santorio, Robert Fludd and Cornelius Drebble. However, the principle on which it was based was used in the Hellenic period and described even earlier by Empedocles in book On Nature in 460 BCE. This is part of a general pattern in the Galileo hagiography, inventions and discoveries that were made by several researchers during his lifetime are attributed solely to Galileo even when he was not even the first to have made them.

At just 22, he published a book onhydrostatic balance, giving him his first bit of fame.

 This ‘book’, La Bilancetta or The Little Balance was actually a booklet or pamphlet and only exists in a few manuscripts so during his lifetime never printed. He used it together with another pamphlet on determining centres of gravity to impress and win patrons within the mathematical community such as Guidobaldo del Monte and Christoph Clavius; in this he was successful.

He attended medical school but, for financial reasons, he had to drop out and work as a tutor. Nevertheless, he eventually became chair of the mathematics department at theUniversity of Pisa.

He studied medicine at the University of Pisa because that was the career that his father had determined for him. He dropped out, not for financial reasons but because he wanted to become a mathematician and not a physician. He studied mathematics privately in Florence and having established his abilities with the pamphlets mentioned above was, with the assistance of his patrons, appointed to teach mathematics in Pisa. However, due to his innate ability to piss people off his contract was terminated after only three years. His patrons now helped him to move to the University of Padua.

He taught at Padua for nearly 20 years, and it’s there where he turned from reasonably well-known Galileo Galilei to Galileo[emphasis in original]. Like the great Italian artists of his age, he became so talented and renowned that soon just his first name sufficed.

This is simply rubbish. He remained virtually unknown outside of Padua until he made his telescopic discoveries in 1610. He turned those discoveries into his exit ticket and left Padua as soon as possible. As for his name, he is, for example, known in English as Galileo but in German as Galilei.

We now turn to mechanics the one field in which Galileo can really claim more than a modicum of originality. However, even here our author drops a major clangour.

Through experimentation, he determined that a feather falls slower than a rock not because of the contrasting weight but because of the extra friction caused by the displacement of Earth’s atmosphere on the flatter object. 

Through experimentation! Where and when did Galileo build his vacuum chamber? Our author missed an opportunity here. This was, of course, Galileo’s most famous thought experiment in which he argues rationally that without air resistance all objects would fall at the same rate. In fact Galileo’s famous use of thought experiments doesn’t make an appearance in this account at all.

Galileo built on this foundation a mathematical formula that showed the rate of acceleration for falling objects on Earth. Tying math to physics, he essentially laid the groundwork for later studies of inertia. These mechanical discoveries provided a firm launching point for Isaac Newton’s further modernization of the field.

It is time for the obligatory statement that the mean speed formula the basis of the mathematics of free fall was known to the Oxford Calculatores and the Paris Physicists in the fourteenth century and also the laws of free fall were already known to Giambattista Benedetti in the sixteenth century. As to inertia, Galileo famously got it wrong and Newton took the law of inertia from Descartes, who in turn had it from Isaac Beeckman and not Galileo. In the late sixteenth and early seventeenth centuries several researchers tied mathematics to physics, many of them before Galileo. See comment above about attributing the work of many solely to Galileo. We now turn to astronomy!

In the early 1600s, despite Copernicus’s elegant heliocentric model of the solar system having debuted more than a half-century earlier, skeptics remained. Indeed, there was an ongoing divide among astronomers; some favored the Copernican model while others clung to the traditional Ptolemaic premise adopted by the Catholic Church, which put the earth at the universe’s center. Even Tycho Brahe, a leading post-Copernican astronomer, favored geocentrism, though his Tychonic system did make some allowances for Copernicus’s less controversial ideas. Brahe’s position helped him avoid the fate of heliocentrist Giordano Bruno who was burned at the stake by the Catholic Inquisition in 1600. This heated astronomical climate awaited Galileo Galilei.

There is nothing particularly elegant about Copernicus’ heliocentric model of the solar system. In fact it’s rather clunky due to his insistence, after removing the equant point, of retaining the so-called Platonic axiom of uniform circular motion. His model was in fact more cluttered and less elegant than the prevailing geocentric model from Peuerbach. Sceptics didn’t remain, as our author puts it, implying in this and the following sentences that there was no reason other than (religious) prejudice for retaining a geocentric model. Unfortunately, as I never tire of repeating, Copernicus’ model suffered from a small blemish, a lack of proof. In fact the vast majority of available empirical evidence supported a geocentric system. You know proof is a fundamental element of all science, including astronomy. If I were playing mythology of science bingo I would now shout full house with the introduction of Giordano Bruno into the mix. No, Giordano was not immolated because he was a supporter of heliocentricity.

Like Bruno, Galileo knew Copernicus was right, and he set out to prove it. Early in the seventeenth century, he received word about a new invention created by the German-Dutch spectacle-makerHans Lippershey In 1608, Lippershey used his knowledge of lenses to make a refracting telescope, which used lenses, an eye piece, and angular strategies to bend light, allowing in more of it. More light could clarify and magnify a desired object, and Lippershey’s rudimentary design could make something appear about three times bigger. Galileo, though he never saw a telescope in person nor even designs of one, heard a basic description of it, checked the information against his brain’s enormous database, realized it could work, and built one of his own. A better one.

Comparing Bruno with Galileo is really something one should avoid doing. Our author’s description of how a refracting telescope works is, I admit, beyond my comprehension, as the function of a refracting telescope is apparently beyond his. The claim that Galileo never saw a telescope, which he made himself, has been undermined by the researches of Mario Biagioli, who argues convincingly that he probably had seen one. I love the expression “checked the information against his brain’s enormous database.” I would describe it not so much as hyperbole as hyperbollocks!

With his improved telescope he could magnify objects thirty times, and he immediately pointed it to the once unknowable heavens and transformed astronomy in numerous ways:

I will start with the general observation that Galileo was by no means the only person pointing a telescope at the heavens in the period between 1609 and 1613, which covers the discoveries described below. He wasn’t even the first that honour goes to Thomas Harriot. Also, all of the discoveries were made independently either at roughly the same time or even earlier than Galileo. If Galileo had never heard of the telescope it would have made virtually no difference to the history of astronomy. He had two things in his favour; he was in general a more accurate observer that his competitors and he published first. Although it should be noted that his principle publication, the Sidereus Nuncius, is more a press release that a scientific report. The first telescope Galileo presented to the world was a 9X magnification and although Galileo did build a 30X magnification telescope most of his discoveries were made with a 20X magnification model. The competitors were using very similar telescopes. “…the once unknowable heavens” we actually already knew quite a lot about the heavens through naked-eye observations.

  • It was assumed that the moon, like all the heavenly spheres, was perfectly smooth. Galileo observed craters and mountains. He inferred, accurately, that all celestial objects had blemishes of their own.

This was actually one of Galileo’s greatest coups. Thomas Harriot, who drew telescopic images of the moon well before Galileo did not realise what he was seeing. After seeing Galileo’s drawings of the moon in the Sidereus Nuncius, he immediately realised that Galileo was right and changed his own drawing immediately. One should, however, be aware of the fact that throughout history there were those who hypothesised that the shadows on the moon were signs of an uneven surface.

  • Though Jupiter had been observed since the ancient world, what Galileo was the first to discover was satellites orbiting around it — the Jovian System. In other words, a planet other than the Earth had stuff orbiting it. It was another brick in Copernicus’s “we’re not that important” wall.

And as I never tire of emphasising, Simon Marius made the same discovery one day later. I have no idea what Copernicus’s “we’re not that important” wall is supposed to be but the discovery of the moons of Jupiter is an invalidation of the principle in Aristotelian cosmology that states that all celestial bodies have a common centre of rotation; a principle that was already violated by the Ptolemaic epicycle-deferent model. It says nothing about the truth or lack of it of either a geocentric or heliocentric model of the cosmos.

  • Pointing his telescope at the sun, Galileo observed sunspots. Though the Chinese first discovered them in 800 BC, as Westerners did five hundred years later, no one had seen or sketched them as clearly as Galileo had. It was another argument against the perfect spheres in our sky.

Telescopic observations of sunspots were first made by Thomas Harriot. The first publication on the discovery was made by Johannes Fabricius. Galileo became embroiled in a meaningless pissing contest with the Jesuit astronomer, Christoph Scheiner, as to who first discovered them. The best sketches of the sunspots were made by Scheiner in his Rosa Ursina sive Sol (Bracciano, 1626–1630).

  • Galileo also discovered that Venus, like the moon, has phases (crescent/quarter/half, waxing/waning, etc.). This was a monumental step in confirming Copernicus’s theory, as Venusian phases require certain angles of sunlight that a geocentric model does not allow.

The phases of Venus were discovered independently by at least four observers, Thomas Harriot, Simon Marius, Galileo and the Jesuit astronomer Paolo Lembo. The astronomers of the Collegio Romano claimed that Lembo had discovered them before Galileo but dating the discoveries is almost impossible. In a geocentric model Venus would also have phases but they would be different to the ones observed, which confirmed that Venus, and by analogy Mercury, whose phases were only observed much later, orbits the Sun. Although this discovery refutes a pure geocentric system it is still compatible with a Capellan system, in which Venus and Mercury orbit the Sun in a geocentric model, which was very popular in the Middle ages and also with any of the Tychonic and semi-Tychonic models in circulation at the time so it doesn’t really confirm a heliocentric model

  • The observable hub of the Milky Way galaxy was assumed to be, just as it looks to us, a big, milky cloud. Galileo discovered it was not a cloud, but a huge cluster of stars. (We now know it numbers in the billions.)

Once again a multiple discovery made by everybody who pointed a telescope at the heavens beginning with Lipperhey.

Galileo not only confirmed Copernicus’s heliocentric theory, but he allowed the likes of Johannes Kepler to more accurately plot out the planets’ orbits, Isaac Newton to explain how it was happening, and Albert Einstein to explain why. It was such a colossal step forward for the observable universe that some people didn’t even believe what they were seeing in the telescope, electing to instead remain skeptical of Galileo’s “sorcery.”

Galileo did not in any way confirm Copernicus’ heliocentric theory. In fact heliocentricity wasn’t confirmed until the eighteenth century. First with Bradley’s discovery of stellar aberration in 1725 proving the annual orbit around the sun and then the determination of the earth’s shape in the middle of the century indirectly confirming diurnal rotation. The telescopic observations made by Galileo et al had absolutely nothing to do with Kepler’s determination of the planetary orbits. Newton’s work was based principally on Kepler’s elliptical system regarded as a competitor to Copernicus’ system, which Galileo rejected/ignored, and neither Galileo nor Copernicus played a significant role in it. How Albert got in here I have absolutely no idea. Given the very poor quality of the lenses used at the beginning of the seventeenth century and the number of optical artifacts that the early telescopes produced, people were more than justified in remaining skeptical about the things apparently seen in telescopes.

Ever the watchdog on sorcery, it was time for the Catholic Church to guard its territory. Protective of geocentrism and its right to teach us about the heavens, the Church had some suggestions about exactly where the astronomer could stick his telescope. In 1616, under the leadership of Pope Paul V, heliocentrism was deemed officially heretical, and Galileo was instructed “henceforth not to hold, teach, or defend it in any way.”

The wording of this paragraph clearly states the author’s prejudices without consideration of historical accuracy. Galileo got into trouble in 1615/16 for telling the Catholic Church how to interpret the Bible, a definitive mistake in the middle of the Counter Reformation. Heliocentrism was never deemed officially heretical. The injunction against Galileo referred only to heliocentrism as a doctrine i.e. a true theory. He and everybody else were free to discuss it as a hypothesis, which many astronomers preceded proceeded to do.

A few years later, a confusing stretch of papal leadership got Galileo into some trouble. In 1623,Pope Urban VIII took a shine to Galileo and encouraged his studies by lifting Pope Paul’s ban. A grateful Galileo resumed his observations and collected them into his largest work, 1632’s “Dialogue Concerning the Two Chief World Systems” In it, he sums up much of his observations and shows the superiority of the newer heliocentric model. The following year, almost as if a trap were set, the Catholic Inquisition responded with a formal condemnation and trial, charging him with violating the initial 1616 decree. Dialogue was placed on the Church’s Index of Prohibited Books.

Maffeo Barberini, Pope Urban VIII, had been a good friend of Galileo’s since he first emerged into the limelight in 1611 and after he was elected Pope did indeed show great favour to Galileo. He didn’t, however, lift Paul V’s ban. It appears that he gave Galileo permission to write a book presenting the geocentric and heliocentric systems, as long as he gave them equal weight. This he very obviously did not do; Galileo the master of polemic skewed his work very, very heavily in favour of the heliocentric system. He had badly overstepped the mark and got hammered for it.  He, by the way, didn’t resume his observations; the Dialogo is based entirely on earlier work. One is, by the way, condemn after being found guilty in a trial not before the trial takes place when one is charged or accused.

Galileo’s popularity, combined with a sheepish Pope Urban, limited his punishment to a public retraction and house arrest for his remaining days. At nearly 70, he didn’t have the strength to resist. Old, tired, and losing his vision after years of repeatedly pointing a telescope at the brightest object in the solar system, he accepted his sentence. Blind and condemned, his final years were mostly spent dictating “Two New Sciences,” which summarized his 30 years of studying physics.

Galileo’s popularity would not have helped him, exactly the opposite. People who were highly popular and angered the Church tended to get stamped on extra hard, as an example to the masses. Also, Urban was anything but sheepish. The public retraction was standard procedure for anyone found guilty by the Inquisition and the transmission of his sentence from life imprisonment to house arrest was an act of mercy to an old man by an old friend. Whether Galileo’s telescopic observations contributed to his blindness is disputed and he hadn’t really made many observations since about 1613. The work summarised in the Discorsi was mostly carried out in the middle period of his life between 1589 and 1616.

The author now veers off into a discussion, as to who is the father or founder of this or that and why one or other title belongs to Copernicus, Newton, Aristotle, Bacon etc. rather than Galileo. Given his belief that one can rank The Top 30 Most Influential Western European Figures in History, it doesn’t surprise me that he is a fan of founder and father of titles. They are, as regular readers will already know, in my opinion a load of old cobblers. Disciplines or sub-disciplines are founded or fathered over several generations by groups of researchers not individuals.

His article closes with a piece of hagiographical pathos:

Moreover, Galileo’s successes were symbolic of a cornerstone in modern science. His struggle against the Church embodied the argument that truth comes from experience, experiments, and the facts — not dogma. He showed us authority and knowledge are not interchangeable. Though the Inquisitors silenced him in 1633, his discoveries, works, and ideas outlived them. For centuries, he has stood as an inspiration for free thinkers wrestling against ignorant authority.

This is typical exaggerated presentation of the shabby little episode that is Galileo’s conflict with the Catholic Church. It wasn’t really like that you know. Here we have the heroic struggle of scientific truth versus religious dogma, a wonderful vision but basically pure bullshit. What actually took place was that a researcher with an oversized ego, Galileo, thought he could take the piss out of the Pope and the Catholic Church. As it turned out he was mistaken.

Being a history teacher I’m sure our author would want me to grade his endeavours. He has obviously put a lot of work into his piece so I will give him an E for effort. However, it is so strewn with errors and falsities that I can only give him a F for the content.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Filed under History of Astronomy, History of Optics, History of science, Myths of Science, Renaissance Science