Category Archives: History of Optics

Why doesn’t he just shut up?

Neil deGrasse Tyson (NdGT), probably the most influential science communicator in the world, spends a lot of time spouting out the message that learning science allows you to better detect bullshit, charlatans, fake news etc. etc. However it apparently doesn’t enable you to detect bullshit in the history of science, at least judging by NdGT’s own record on the subject. Not for the first time, I was tempted recently to throw my computer through the window upon witnessing NdGT pontificating on the history of science.

On a recent video recorded for Big Think, and also available on Youtube and already viewed by 2.6 million sycophants, he answers the question “Who’s the greatest physicist in history?” His answer appears under the title My Man, Sir Isaac Newton. Thoughtfully, Big Think have provided a transcription of NdGT’s blathering that I reproduce below for your delectation before I perform a Hist_Sci Hulk autopsy upon it.

Question: Who’s the greatest physicist in history?DeGrasse Tyson:    Isaac Newton.  I mean, just look… You read his writings.  Hair stands up… I don’t have hair there but if I did, it would stand up on the back of my neck.  You read his writings, the man was connected to the universe in ways that I never seen another human being connected.  It’s kind of spooky actually.  He discovers the laws of optics, figured out that white light is composed of colors.  That’s kind of freaky right there.  You take your colors of the rainbow, put them back together, you have white light again.  That freaked out the artist of the day.  How does that work?  Red, orange, yellow, green, blue, violet gives you white.  The laws of optics.  He discovers the laws of motion and the universal law of gravitation.  Then, a friend of his says, “Well, why do these orbits of the planets… Why are they in a shape of an ellipse, sort of flattened circle?  Why aren’t… some other shape?”  He said, you know, “I can’t… I don’t know.  I’ll get back to you.”  So he goes… goes home, comes back couple of months later, “Here’s why.  They’re actually conic sections, sections of a cone that you cut.”  And… And he said, “Well, how did find this out?  How did you determine this?”  “Well, I had to invent integral and differential calculus to determine this.”  Then, he turned 26.  Then, he turned 26.  We got people slogging through calculus in college just to learn what it is that Isaac Newtown invented on a dare, practically.  So that’s my man, Isaac Newton. 

“WHO’S THIS BLATHERING TYSON FOOL?”

Let us examine the actual history of science content of this stream of consciousness bullshit. We get told, “He discovers the laws of optic…!” Now Isaac Newton is indeed a very important figure in the history of physical optics but he by no means discovered the laws of optics. By the time he started doing his work in optics he stood at the end of a two thousand year long chain of researchers, starting with Euclid in the fourth century BCE, all of whom had been uncovering the laws of optics. This chain includes Ptolemaeus, Hero of Alexandria, al-Kindi, Ibn al-Haytham, Ibn Sahl, Robert Grosseteste, Roger Bacon, John Pecham, Witelo, Kamal al-Din al-Farisi, Theodoric of Freiberg, Francesco Maurolico, Giovanni Battista Della Porta, Friedrich Risner, Johannes Kepler, Thomas Harriot, Marco Antonio de Dominis, Willebrord Snellius, René Descartes, Christiaan Huygens, Francesco Maria Grimaldi, Robert Hooke, James Gregory and quite a few lesser known figures, much of whose work Newton was well acquainted with. Here we have an example of a generalisation that is so wrong it borders on the moronic.

What comes next is on safer ground, “…figured out that white light is composed of colors…” Newton did in fact, in a series of groundbreaking experiment, do exactly that. However NdGT, like almost everybody else is apparently not aware that Newton was by no means the first to make this discovery. The Bohemian Jesuit scholar Jan Marek (or Marcus) Marci (1595–1667) actually made this discovery earlier than Newton but firstly his explanation of the phenomenon was confused and largely wrong and secondly almost nobody knew of his work so the laurels go, probably correctly, to Newton.

NdGT’s next statement is for a physicist quite simply mindboggling he says, “That freaked out the artist of the day.  How does that work?  Red, orange, yellow, green, blue, violet gives you white.” Apparently NdGT is not aware of the fact that the rules for mixing coloured light and those for mixing pigments are different. I got taught this in primary school; NdGT appears never to have learnt it.

Up next are Newton’s contributions to mechanics, “He discovers the laws of motion and the universal law of gravitation.  Then, a friend of his says, “Well, why do these orbits of the planets… Why are they in a shape of an ellipse, sort of flattened circle?  Why aren’t… some other shape?”  He said, you know, “I can’t… I don’t know.  I’ll get back to you.”  So he goes… goes home, comes back couple of months later, “Here’s why.  They’re actually conic sections, sections of a cone that you cut.””

Where to begin? First off Newton did not discover either the laws of motion or the law of gravity. He borrowed all of them from others; his crowing achievement lay not in discovering them but in the way that he combined them. The questioning friend was of course Edmond Halley in what is one of the most famous and well document episodes in the history of physics, so why can’t NdGT get it right? What Halley actually asked was, assuming an inverse squared law of attraction what would be the shape of aa planetary orbit? This goes back to a question posed earlier by Christopher Wren in a discussion with Halley and Robert Hooke, “would an inverse squared law of attraction lead to Kepler’s laws of planetary motion?” Halley could not solve the problem so took the opportunity to ask Newton, at that time an acquaintance rather than a friend, who supposedly answered Halley’s question spontaneously with, “an ellipse.” Halley then asked how he knew it and Newton supposedly answered, “I have calculated it.” Newton being unable to find his claimed calculation sent Halley away and after some time supplied him with the nine-page manuscript De motu corporum in gyrum, which in massively expanded form would become Newton’s Principia.

NdGT blithely ignoring the, as I’ve said, well documented historical facts now continues his #histsigh fairy story, “And he said, “Well, how did find this out?  How did you determine this?”  “Well, I had to invent integral and differential calculus to determine this.”” This is complete an utter bullshit! This is in no way what Newton did and as such he also never claimed to have done it. In fact one of the most perplexing facts in Newton’s biography is that although he was a co-discoverer/co-inventor of the calculus (we’ll ignore for the moment the fact that even this is not strictly true, read the story here) there is no evidence that he used calculus to write Principia.

NdGT now drops his biggest historical clangour! He says, “Then, he turned 26.  Then, he turned 26.  We got people slogging through calculus in college just to learn what it is that Isaac Newtown invented on a dare, practically.  So that’s my man, Isaac Newton.” Newton was twenty-six going on twenty seven when he carried out the optics research that led to his theory of colours in 1666-67 but the episode with Halley concerning the shape of planetary orbits took place in 1682 when he was forty years old and he first delivered up De motu corporum in gyrum two years later in 1684. NdGT might, as an astro-physicist, be an expert on a telescope but he shouldn’t telescope time when talking about historical events.

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Filed under History of Optics, History of science, Myths of Science, Newton

Bringing the heavens down to earth

The Frisian Protestant pastor and amateur astronomer, David Fabricius, was beaten to death by one of his parishioners on 7 May 1617. Because he corresponded with both Tycho Brahe and Johannes Kepler and was quite a significant figure in Early Modern astronomy the Society for the History of Astronomy had a short post on Facebook commemorating his death on last Sunday, which contained the following claim:

David Fabricius was, following Galileo’s lead, one of the early users of the telescope in astronomy[1]

This claim contains two factual errors. The first is that it was Johannes, David’s son, who introduced the telescope into the Fabricius household and not David, although David soon joined his son in his telescopic observations. I’ll explain further later.

The Fabricii, father and son, remain largely unknown to the world at large but a monument to them both was erected in the churchyard in Osteel, where David had been village pastor, in 1895.

The second error is more serious because it indirectly perpetuates a widespread myth concerning the introduction of the telescope into astronomy and Galileo’s role in it. There is a popular perception that Galileo, and only Galileo, had the genius, the wit, the vision to realise that the newly invented telescope could be used as an astronomical instrument and that he singlehandedly pioneered this new discipline, telescopic astronomy. This is of course complete rubbish and seriously distorts the early history of the telescope in astronomy and does a major disservice to all of the others who contributed to that early history. I will admit to having done a small fist pump when I read the following in John Heilbron’s Galileo biography:

The transformation of the Dutch gadget into an instrument powerful to discover novelties in the heavens did not require a Galileo. His unique strength lay in interpreting what he saw.[2]

That the telescope could be used as an astronomical instrument was recognised during its very first public demonstration by its inventor, the German/Dutch spectacle maker Hans Lipperhey, which took place at the court of Prince Maurice of Nassau in Den Haag during the Dutch-Spanish Peace Conference on an unknown day between 25 and 29 September 1608. We have a detailed account of this demonstration from a French flyer or newsletter describing the first visit of the Ambassador of Siam to Europe, the Ambassador being present at the demonstration. Through this flyer the news of the new invention spread rapidly throughout Europe. Amongst the other descriptions of the wonderful abilities of this “…device by means of which all things at a very great distance can be seen as if they were nearby, by looking through glasses…” we can read the following:

The said glasses are very useful at sieges & in similar affairs, because one can distinguish from a mile’s distance & beyond several objects very well, as if they are near & 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. [my emphasis]

The first astronomer to build and use a telescope as an astronomical instrument was Thomas Harriot, who drew a sketch of the moon using a telescope on 26 July 1609 before Galileo even had a telescope.

Thomas Harriot’s 1609 telescopic sketch of the moon

This of course raises the question where Harriot obtained his knowledge of this instrument. In the early phase of the telescopes existence it became a common habit to present heads of state and other worthies telescopes as presents. In England James I (VI of Scotland) was presented with one at the end of an elaborate masque created for the occasion by Ben Jonson, the Renaissance playwright. The telescope was obtained from the United Provinces through the offices of Cornelis Drebbel, the Dutch inventor and scholar, who was employed at James’ court. This telescope was probably Harriot’s, who enjoyed good connections to court circles, introduction to the instrument.

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

Harriot did not observe alone. In London he observed together with his instrument maker Christopher Tooke in London, whilst Harriot’s pupil the landowner and MP, Sir William Lower observed in Wales, together with his neighbour John Prydderch, with a telescope made by Harriot and Tooke. Each pair took turns in observing comparing their results and then Harriot and Lower compared results by letter. This meant that they could be reasonably certain that what they had observed was real and not some optical artefacts produced by the poor quality of the lenses they were using. So here we have four telescopic astronomical observers independent of Galileo’s activities.

In Franconia Simon Marius also built and used telescopes in 1609, at the time unaware of the similar activities of Galileo in Padua. As I have written in another blog post Marius discovered the four largest moons of Jupiter just one day later and independently of Galileo. Marius also made the first telescopic observations of the Andromeda Nebula, significant because the Andromeda Nebula would later become the first galaxy to be recognised as a galaxy outside of our galaxy.

Simon Marius frontispiece from his Mundus Jovialis

Another telescopic pioneer in Southern Germany was the Jesuit astronomer in Ingolstadt, Christoph Scheiner, who famously became embroiled in a dispute with Galileo over who had first observed sunspots with a telescope and what exactly they were.

Christoph Scheinet (artist unknown)

The dispute was rather pointless, as Harriot had actually observed sunspots earlier than both of them and Johannes Fabricius, to whom we will turn next, had already published a report on his sunspot observations unknown to the two adversaries. Christoph Scheiner and his assistant, another Jesuit astronomer, Johann Baptist Cysat, would go on to make several important contributions to telescopic astronomy.

Johann Baptist Cysat, holding a Jacob’s staff

Johannes Fabricius brought his telescope home from the University of Leiden, where he had almost certainly learnt of this instrument through the lectures of Rudolph Snel van Royan, professor of mathematics and father of the better know Willibrord Snel of Snell’s law of refraction fame. Rudolph Snel van Royan was probably the first university professor to lecture on the telescope as a scientific instrument already in 1610.

Rudolph Snel van Royan
Source: Wikimedia Commons

It is also known that Cort Aslakssøn and Christian Longomontanus acquired lenses and built their own telescopes in the first couple of years of telescopic astronomy in Copenhagen, but unfortunately I haven’t, until now, been able to find any more details of activities in this direction. If any of my readers could direct me to any literature on the subject I would be very grateful.

Christian Severin known as Longomontanus

Turning to Italy we find the astronomers on the Collegio Romano under the watchful eye of Christoph Clavius making telescopic astronomical observations before Galileo published his Sidereus Nuncius in 1610, using a Dutch telescope sent to Odo van Maelcote by one of his earlier students Peter Scholier. Grégoire de Saint-Vincent would later claim that he and Odo van Maelcote were probably the very first astronomers to observe Saturn using a telescope. It was the astronomers of the Collegio Romano, most notably Giovanni Paolo Lembo and Christoph Grienberger, who would then go on to provide the very necessary independent confirmation of the discoveries that Galileo had published in the Sidereus Nuncius.

As can be seen Galileo was anything but the singlehanded pioneer of telescopic astronomy in those early months and years of the discipline. What is interesting is that those working within the discipline were not isolated lone warriors but a linked network, who exchanged letter and publications with each other.

Some of the connections that existed between the early telescopic astronomers are listed here: Harriot had corresponded extensively with Kepler and was very well informed about what Tycho and the other continental astronomers were up to. David Fabricius corresponded with Kepler and Tycho and even visited Tycho in Prague but unfortunately didn’t meet Kepler on his visit. Johannes would later take up correspondence with Kepler. Tycho corresponded with Magini in Bologna who passed on his news to both Galileo and Clavius. Clavius was also very well informed of all that was going on in European astronomy by the Jesuit network. Almost all of the Jesuit astronomers were students of his. Marius corresponded with Kepler, who published many of his astronomical discoveries before he did, and with David Fabricius, whom he had got to know when he visited Tycho in Prague to study astronomy. Longomontanus had earlier been Tycho’s chief assistant and corresponded with Kepler after he left Prague to return to Copenhagen. Interestingly another of Tycho’s assistants, Johannes Eriksen, visited both David Fabricius in Friesland and Thomas Harriot in London on the same journey.

What we have here is not Galileo Galilei as singlehanded pioneer of telescopic astronomy but a loosely knit European community of telescopic astronomers who all recognised and utilised the potential of this new instrument shortly after it appeared. They would soon be joined by others, in this case mostly motivated by Galileo’s Sidereus Nuncius, a few of them even supplied with telescopes out of Galileo’s own workshop. However what is very important to note is that although Galileo was without doubt the best telescopic observer of that first generation and certainly won the publication race, all of the discoveries that he made were also made independently and contemporaneously by others, so nothing would have been lost if he had never taken an interest in the spyglass from Holland.

 

 

 

 

 

[1] Because I pointed out the errors contained in this claim in a comment, it has now been removed from the Facebook post!

[2] J. L. Heilbron, Galileo, OUP, 2010, p. 151

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A birthday amongst the stars

Readers will probably be aware that as well as writing this blog I also hold, on a more or less regular basis, semi-popular, public lectures on the history of science. These lectures are as diverse as this blog and have been held in a wide variety of places. However I have, over the years, held more lectures in the Nürnberg Planetarium than anywhere else and last Thursday I was once again under the dome, this time not to hold a lecture but to help celebrate the ninetieth birthday of this august institution.

Before the twentieth century the term planetarium was a synonym for orrery, a mechanical model, which demonstrates the movements of the planets in the solar system. The beginnings of the planetarium in the modern sense was as Walther Bauersfeld, an engineer of the German optics company Zeiss, produced the plans for the construction of a planetarium projector based on earlier concepts. In 1923 the world’s first planetarium projector, the Zeiss Mark I, was demonstrated in the Zeiss factory in Jena and two months later on 21 October in the Deutschen Museum in Munich. Following further developments the first planetarium was opened in the Deutschen Museum on 7 May 1925.

Zeiss Mark I Planetarium Projector

Various German town and cities followed suit and the city council of Nürnberg signed a contract with Zeiss for a planetarium projector on 12 February 1925. The contract called for the city council to pay Zeiss 150, 000 Reichsmark ( a small fortune) in three instalments and 10% of the takings from the public shows. In a building on Rathenauplatz designed by Otto Ernst Schweizer the Nürnberg planetarium opened ninety years ago on 10 April 1927.

Original Nürnberg Planetarium

Fitted out with a new Zeiss Mark II projector the first of the so-called dumbbell design projectors with a sphere at each end for the north and south hemispheres. It was the world’s ninth planetarium.

Zeiss Mark II Planetarium Projector

From the very beginning the planetarium was born under a bad sign as the NSDAP (Nazi) city councillor, Julius Streicher, (notorious as the editor of the anti-Semitic weekly newspaper Der Stürmer) vehemently opposed the plans of the SPD council to build the planetarium. On 30 January 1933 the NSDAP seized power in Germany and the days of the planetarium were numbered. In November the planetarium director was ‘persuaded’ to recommend closing the planetarium and at the beginning of December it was closed. There were discussions about using the building for another purpose but Streicher, now Gauleiter (district commissioner) of Franconia was out for revenge. In March 1934 the planetarium was demolished on Streicher’s orders, with the argument that it looked too much like a synagogue! However the projector, and all the technical equipment, was rescued and put into storage.

Historischer Kunstbunker Entrance: There are guided tours

During the Second World War the projector was stored together with the art treasures of the city in the Historischer Kunstbunker (historical art bunker), a tunnel under the Castle of Nürnberg.

Following the war, in the 1950s, as Nürnberg was being rebuilt the city council decided to rebuild the planetarium and on 11 December 1961 it was reopened on the new site on the Plärrer, with an updated Zeiss Mark III. During the celebrations for the five hundredth anniversary of the death of Nicolaus Copernicus in 1973, whose De revolutionibus was printed and published in Nürnberg, the planetarium became the Nicolaus-Copernicus-Planetarium. In 1977 the Mark III projector was replaced with a Mark V, which is still in service and in 2010 the planetarium entered the twenty-first century with a digital Full-Dome projector.

Nicolaus-Copernicus-Planetarium am Plärrer in Nürnberg (2013)

The Zeiss Mark V Planetarium Projector in Nürnberg

Since the 1990’s the planetarium has been part of the City of Nürnberg’s adult education complex and alongside the planetarium programme it is used extensively for STEM lectures. I shall be holding my next lecture there on 28 November this year about Vannevar Bush, Claude Shannon, Robert H Goddard and William Shockley- Four Americans Who Shaped the Future (in German!) and if you’re in the area you’re welcome to come and throw peanuts.

 

 

 

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

On an excursion

If you wish to read the latest words of wisdom, this time on the conception and invention of the reflecting telescope, then you will have to take an excursion to AEON magazine, where you can peruse:

How many great minds does it take to invent a telescope?

Isaac Newton’s reflecting telescope of 1671. Photo ©The Royal Society, London

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Filed under History of Astronomy, History of Optics, History of Technology, Newton

If you are going to blazon out history of science ‘facts’ at least get them right

Today’s Torygraph has a short video entitled 10 Remarkable Facts about rainbows, at 57 seconds it displays the following text:

Until the 17th Century, no one had

the faintest idea what a rainbow

was, how it got there or what it was

made of…

This is, of course, simply not true. In the 14th century the Persian scholar Kamal al-Din Hasan ibn Ali ibn Hasan al-Farisi (1267–1319) gave the correct scientific explanation of the rainbow in his Tanqih al-Manazir (The Revision of the Optics). Almost contemporaneously the German scholar Theodoric of Freiberg (c. 1250–c. 1310) gave the same correct explanation in his De iride et radialibus impressionibus (On the Rainbow and the impressions created by irradiance). The two scholars arrived at their conclusion independently of each other but both of them did experiments involving the study of light rays passing through glass spheres full of water and both scholars were influenced by the optical theories of Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham. Unfortunately both explanations disappeared and it was in fact first in the 17th Century that the Croatian scholar Marco de Antonio Dominis (1560–1624) once again gave an almost correct explanation of the rainbow in his Tractatus de radiis visus et lucis in vitris, perspectivis et iride.

De Dominis' explanation of the rainbow Source: Wikimedia Commons

De Dominis’ explanation of the rainbow
Source: Wikimedia Commons

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Isaac and the apple – the story and the myth

The tale of Isaac Newton and the apple is, along with Archimedes’ bath time Eureka-ejaculation and Galileo defiantly mumbling ‘but it moves’ whilst capitulating before the Inquisition, is one of the most widely spread and well known stories in the history of science. Visitors to his place of birth in Woolsthorpe get to see a tree from which the infamous apple is said to have fallen, inspiring the youthful Isaac to discover the law of gravity.

The Woolsthorpe Manor apple tree Source:Wikimedia Commons

The Woolsthorpe Manor apple tree
Source:Wikimedia Commons

Reputed descendants of the tree exist in various places, including Trinity College Cambridge, and apple pips from the Woolsthorpe tree was taken up to the International Space Station for an experiment by the ‘first’ British ISS crew member, Tim Peake. Peake’s overalls also feature a Principia patch displaying the apple in fall.

Tim Peake's Mission Logo

Tim Peake’s Mission Logo

All of this is well and good but it leads automatically to the question, is the tale of Isaac and the apple a real story or is it just a myth? The answer is that it is both.

Modern historians of Early Modern science tend to contemptuously dismiss the whole story as a myth. One who vehemently rejects it is Patricia Fara, who is an expert on Newtonian mythology and legend building having researched and written the excellent book, Newton: The Making of Genius[1]. In her Science: A Four Thousand Year History she has the following to say about the apple story[2]:

More than any other scientific myth, Newton’s falling apple promotes the romantic notion that great geniuses make momentous discoveries suddenly and in isolation […] According to simplistic accounts of its [Principia’s] impact, Newton founded modern physics by introducing gravity and simultaneously implementing two major transformations in methodology: unification and mathematization. By drawing a parallel between an apple and the Moon, he linked an everyday event on Earth with the motion of the planets through the heavens, thus eliminating the older, Aristotelian division between the terrestrial and celestial realms.

[…]

Although Newton was undoubtedly a brilliant man, eulogies of a lone genius fail to match events. Like all innovators, he depended on the earlier work of Kepler, Galileo, Descartes and countless others […]

[…]

The apple story was virtually unknown before Byron’s time. [Fara opens the chapter with a Byron poem hailing Newton’s discovery of gravity by watching the apple fall].

Whilst I would agree with almost everything that Fara says, here I think she is, to quote Kepler, guilty of throwing out the baby with the bath water. But before I explain why I think this let us pass review of the myth that she is, in my opinion, quite rightly rejecting.

The standard simplistic version of the apple story has Newton sitting under the Woolsthorpe Manor apple tree on a balmy summer’s day meditation on mechanics when he observes an apple falling. Usually in this version the apple actually hits him on the head and in an instantaneous flash of genius he discovers the law of gravity.

This is of course, as Fara correctly points out, a complete load of rubbish. We know from Newton’s notebooks and from the draughts of Principia that the path from his first studies of mechanics, both terrestrial and celestial, to the finished published version of his masterpiece was a very long and winding one, with many cul-de-sacs, false turnings and diversions. It involved a long and very steep learning curve and an awful lot of very long, very tedious and very difficult mathematical calculations. To modify a famous cliché the genius of Principia and the theories that it contains was one pro cent inspiration and ninety-nine pro cent perspiration.

If all of this is true why do I accuse Fara of throwing out the baby with the bath water? I do so because although the simplistic story of the apple is a complete myth there really was a story of an apple told by Newton himself and in the real versions, which differ substantially from the myth, there is a core of truth about one step along that long and winding path.

Having quoted Fara I will now turn to, perhaps Newton’s greatest biographer, Richard Westfall. In his Never at Rest, Westfall of course addresses the apple story:

What then is one to make of the story of the apple? It is too well attested to be thrown out of court. In Conduitt’s version one of four independent ones, …

Westfall tells us that the story is in fact from Newton and he told to on at least four different occasions to four different people. The one Westfall quotes is from John Conduitt, who was Newton’s successor at the Royal Mint, married his niece and house keeper Catherine Barton and together with her provided Newton with care in his last years. The other versions are from the physician and antiquarian William Stukeley, who like Newton was from Lincolnshire and became his friend in the last decade of Newton’s life, the Huguenot mathematician Abraham DeMoivre, a convinced Newtonian and Robert Greene who had the story from Martin Folkes, vice-president of the Royal Society whilst Newton was president. There is also an account from Newton’s successor as Lucasian professor, William Whiston, that may or may not be independent. The account published by Newton’s first published biographer, Henry Pemberton, is definitely dependent on the accounts of DeMoivre and Whiston. The most well known account is that of Voltaire, which he published in his Letters Concerning the English Nation, London 1733 (Lettres philosophiques sur les Anglais, Rouen, 1734), and which he says he heard from Catherine Conduitt née Barton. As you can see there are a substantial number of sources for the story although DeMoivre’s account, which is very similar to Conduitt’s doesn’t actually mention the apple, so as Westfall says to dismiss it out of hand is being somewhat cavalier, as a historian.

To be fair to Fara she does quote Stukeley’s version before the dismissal that I quoted above, so why does she still dismiss the story. She doesn’t, she dismisses the myth, which has little in common with the story as related by the witnesses listed above. Before repeating the Conduitt version as quoted by Westfall we need a bit of background.

In 1666 Isaac, still an undergraduate, had, together with all his fellow students, been sent down from Cambridge because of an outbreak of the plague. He spent the time living in his mother’s house, the manor house in Woolsthorpe, teaching himself the basics of the modern terrestrial mechanics from the works of Descartes, Huygens and the Salisbury English translation of Galileo’s Dialogo. Although he came nowhere near the edifice that was the Principia, he did make quite remarkable progress for a self-taught twenty-four year old. It was at this point in his life that the incident with the apple took place. We can now consider Conduitt’s account:

In the year 1666 he retired again from Cambridge … to his mother in Lincolnshire & whilst he was musing in a garden it came to his thought that the power of gravity (wch brought an apple from the tree to the ground) was not limited to a certain distance from the earth but that this power must extend much further than was normally thought. Why not as high as the moon said he to himself & if so that must influence her motion & and perhaps retain her in her orbit, where-upon he fell to calculating what would be the effect of this supposition but being absent from books & taking common estimate in use among Geographers & our seamen before Norwood had measured the earth, that 60 English miles were contained in one degree latitude on the surface of the Earth his computation did not agree with his theory & inclined him to entertain a notion that together with the force of gravity there might be a mixture of that force wch the moon would have if it was carried along in a vortex…[3]

As you can see the account presented here by Conduitt differs quite substantially from the myth. No tree, no apple on the head, no instantaneous discovery of the theory of gravity. What we have here is a young man who had been intensely studying the theory of forces, in particular forces acting on a body moving in a circle, applying what he had learnt to an everyday situation the falling apple and asking himself if those forces would also be applicable to the moon. What is of note here is the fact that his supposition didn’t work out. Based on the data he was using, which was inaccurate, his calculations showed that the forces acting on the apple and those acting on the moon where not the same! An interesting thought but it didn’t work out. Oh well, back to the drawing board. Also of note here is the reference to a vortex, revealing Newton to be a convinced Cartesian. By the time he finally wrote the Principia twenty years later he had turned against Descartes and in fact Book II of Principia is devoted to demolishing Descartes’ vortex theory.

In 1666 Newton dropped his study of mechanics for the meantime and moved onto optics, where his endeavours would prove more fruitful, leading to his discoveries on the nature of light and eventually to his first publication in 1672, as well as the construction of his reflecting telescope.

The Newtonian Reflector Source: Wikimedia Commons

The Newtonian Reflector
Source: Wikimedia Commons

Over the next two decades Newton developed and extended his knowledge of mechanics, whilst also developing his mathematical skills so that when Halley came calling in 1684 to ask what form a planetary orbit would take under an inverse squared law of gravity, Newton was now in a position to give the correct answer. At Halley’s instigation Newton now turned that knowledge into a book, his Principia, which only took him the best part of three years to write! As can be seen even with this briefest of outlines there was definitely nothing instantaneous or miraculous about the creation of Newton’ masterpiece.

So have we said all that needs to be said about Newton and his apple, both the story and the myth? Well no. There still remains another objection that has been raised by historians, who would definitely like to chuck the baby out with the bath water. Although there are, as noted above, multiple sources for the apple-story all of them date from the last decade of Newton’s life, fifty years after the event. There is a strong suspicion that Newton, who was know to be intensely jealous of his priorities in all of his inventions and discoveries, made up the apple story to establish beyond all doubt that he and he alone deserved the credit for the discovery of universal gravitation. This suspicion cannot be simply dismissed as Newton has form in such falsification of his own history. As I have blogged on an earlier occasion, he definitely lied about having created Principia using the, from himself newly invented, calculus translating it back into conventional Euclidian geometry for publication. We will probably never know the final truth about the apple-story but I for one find it totally plausible and am prepared to give Isaac the benefit of the doubt and to say he really did take a step along the road to his theory of universal gravitation one summer afternoon in Woolsthorpe in the Year of Our Lord 1666.

[1] Patricia Fara, Newton: The Making of Genius, Columbia University Press, 2002

[2] Patricia Fara, Science: A Four Thousand Year History, ppb. OUP, 2010, pp. 164-165

[3] Richard S. Westfall, Never at Rest: A Biography of Isaac Newton, ppb. CUP, 1980 p. 154

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Filed under History of Astronomy, History of Mathematics, History of Optics, History of Physics, History of science, Myths of Science, Newton

The Huygens Enigma

The seventeenth century produced a large number of excellent scientific researches and mathematicians in Europe, several of whom have been elevated to the status of giants of science or even gods of science by the writers of the popular history of science. Regular readers of this blog should be aware that I don’t believe in the gods of science, but even I am well aware that not all researches are equal and the contributions of some of them are much greater and more important than those of others, although the progress of science is dependent on the contributions of all the players in the science game. Keeping to the game analogy, one could describe them as playing in different leagues. One thing that has puzzled me for a number of years is what I regard as the Huygens enigma. There is no doubt in my mind whatsoever that the Dutch polymath Christiaan Huygens, who was born on the 14 April 1629, was a top premier league player but when those pop history of science writers list their gods they never include him, why not?

Christiaan Huygens by Caspar Netscher, Museum Hofwijck, Voorburg Source: Wikimedia Commons

Christiaan Huygens by Caspar Netscher, Museum Hofwijck, Voorburg
Source: Wikimedia Commons

Christiaan was the second son of Constantijn Huygens poet, composer, civil servant and diplomat and was thus born into the highest echelons of Dutch society. Sent to university to study law by his father Christiaan received a solid mathematical education from Frans van Schooten, one of the leading mathematicians in Europe and an expert on the new analytical mathematics of Descartes and Fermat. Already as a student Christiaan had contacts to top European intellectuals, including corresponding with Marine Mersenne, who confirmed his mathematical talent to his father. Later in his student life he also studied under the English mathematician John Pell.

Already at the age of twenty-five Christiaan dedicated himself to the scientific life, the family wealth sparing him the problem of having to earn a living. Whilst still a student he established himself as a respected mathematician with an international reputation and would later serve as one of Leibniz’s mathematics teachers. In his first publication at the age of twenty-two Huygens made an important contribution to the then relatively new discipline of probability. In physics Huygens originated what would become Newton’s second law of motion and in a century that saw the development of the concept of force it was Huygens’ work on centripetal force that led Christopher Wren and Isaac Newton to the derivation of the inverse square law of gravity. In fact in Book I of Principia, where Newton develops the physics that he goes on to use for his planetary theory in Book III, he only refers to centripetal force and never to the force of gravity. Huygens contribution to the Newtonian revolution in physics and astronomy was substantial and essential.

In astronomy Christiaan with his brother Constantijn ground their own lenses and constructed their own telescopes. He developed one of the early multiple lens eyepieces that improved astronomical observation immensely and which is still known as a Huygens eyepiece. He established his own reputation as an observational astronomer by discovering Titan the largest moon of Saturn. He also demonstrated that all the peculiar observations made over the years of Saturn since Galileo’s first observations in 1610 could be explained by assuming that Saturn had a system of rings, their appearance varying depending on where Saturn and the Earth were in their respective solar orbits at the time of observations. This discovery was made by theoretical analysis and not, as is often wrongly claimed, because he had a more powerful telescope.

In optics Huygens was, along with Robert Hooke, the co-creator of a wave theory of light, which he used to explain the phenomenon of double refraction in calcite crystals. Unfortunately Newton’s corpuscular theory of light initially won out over Huygens’ wave theory until Young and others confirmed Huygens’ theory in the nineteenth century.

Many people know Huygens best for his contributions to the history of clocks. He developed the first accurate pendulum clocks and was again along with Robert Hooke, who accused him of plagiarism, the developer of the balance spring watch. There were attempts to use his pendulum clocks to determine longitude but they proved not to be reliable enough under open sea conditions.

Huygens’ last book published posthumously, Cosmotheoros, is a speculation about the possibility of alien life in the cosmos.

Huygens made important contributions to many fields of science during the second half of the seventeenth century of which the above is but a brief and inadequate sketch and is the intellectual equal of any other seventeenth century researcher with the possible exceptions of Newton and Kepler but does not enjoy the historical reputation that he so obviously deserve, so why?

I personally think it is because there exists no philosophical system or magnum opus associated with his contributions to the development of science. He work is scattered over a series of relatively low-key publications and he offers no grand philosophical concept to pull his work together. Galileo had his Dialogo and his Discorsi, Descartes his Cartesian philosophy, Newton his Principia and his Opticks. It seems to be regarded as one of the gods of science it is not enough to be a top class premier league player who makes vital contributions across a wide spectrum of disciplines, one also has to have a literary symbol or philosophical methodology attached to ones name to be elevated into the history of science Olympus.

P.S. If you like most English speakers think that his name is pronounced something like Hoi-gens then you are wrong, it being Dutch is nothing like that as you can hear in this splendid Youtube video!

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