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

39 Comments

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

39 responses to “Isaac and the apple – the story and the myth

  1. You can read Stukeley’s account in his own hand at this Royal Society site: https://royalsociety.org/collections/turning-pages/ (scroll down a bit to Memoirs of Sir Isaac Newton’s Life – the apple comes in on page 15).

    P.S. Why is it so hard to comment on WordPress – it keeps trying to get me to log in!!!

  2. Every time the story of Newton’s apple comes up I’m reminded of its role in the thinking of Charles Fourier, the loopy but surprisingly influential utopian socialist. Fourier claimed that he came to his key insight on what was wrong with society when he realized that an apple at an inn he was staying at was priced hundred times higher than apples in his home town. Supposedly this event led to the discovery of “passionate attraction,” the analogue to gravity in Fourier’s physics of human relations. In the full-blown version of this story, four apples were crucial in history: two bad apples and two good apples—the apple in the Garden of Eden, the Apple of Discord that led to the Trojan war (long story), Newton’s apple, and Fourier’s apple.

  3. Really enjoyed this. I love history and its wonderful mysteries😍

  4. Jeb

    “This is of course, as Fara correctly points out, a complete load of rubbish.”

    Depends where you place value here. I like trash, and place a particular high value on trash that contains what is termed ‘legendary proof.’ It helps me to work out what kind of trash I am looking at and allows for more accurate comparison.

    ” is the tale of Isaac and the apple a real story or is it just a myth? The answer is that it is both.”

    I think its a very real story, specifically a foundation legend.

    Legendary proof helps to keep things real here. It seems to work using a form of familiarity creating a “passionate attraction.”

    I remember an awkward moment at a conference when an interested member of the public stood up and shouted ‘no its not a legend the empty treasure chest is kept in my church.’

    H.O.S. places too high a value on myth busting as a form of spectacular public execution. Death by fireworks.

    Resisting the urge as you have done here makes for a more interesting if uncertain tale. Messy uncertainty also keeps things real and very much alive.

    • LucyM

      I just wanted to second the sentiment I think you probably express there. Obviously myths like anything else, should be debunked when demonstrably wrong in fact. But when it’s competitive weighing of historical fragments left by centuries an open-question vocabularly has higher fidelity.

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  6. LucyM

    Awesome piece thank you so much for sharing your knowledge in this way, made accessible to the ordinary person by means of wit and brevity, not watering down.
    I’m struggling with the idea significant numbers of people nurse the sort of misconception assumed by yourself and the historian you review. I’m shamelessly depending personal experience for all or most of this, but I’ve never come across anyone, or read or otherwise been in witness of, anyone nursing the kind of bump-on-the-head stroke of genius explanation for Newton’s theories.
    By the same coin, I think we all or most of us, probably takeaway something like that to begin with. I suppose those that have no interest whatever and put it all to one side then and there, freezing forever the knocked-by-apple explanation, do theoretically carry that frozen misconception around for the rest of their lives. But then again if they have no interest, they probably forget their misconception before too long anyway.
    Or, is there documentary or other evidence of substantial persistent specifically this misconception?

    .

    • Jeb

      The persistent factor in the long history of genius may be the need to understand what it is to be human?

      Its history may map our altering perception and understanding of such desires.

  7. Great post, as ever.
    However, the issue raises a question of caution, at least for me:
    It’s quite easy to imagine a scenario whereby the ‘apple’ story is well known, but no description of the event survived in Newton’s writings (or that of his contemporaries). Wouldn’t it be a pity to conclude newton never said any such thing?

    Many historians would indeed reach this conclusion, and do so in many other instances of similar stories in science. I’m always a little uneasy with this, because of the possibility that the oral tradition of a story survived while evidence/original writings to support it did not.

    So,for example, the story that G. dropped stones of various weights from the tower of Pisa is routinely dismissed because no evidence exists to support it. Many writings of the time survived, with no description of such an experiment. My viewpoint is that many writings of the time but were also lost – so we don’t know for sure that the event didn’t happen. So my approach to these science stories is to state that there is no evidence to support a story if there is none, but to leave the possibility that it happened open (unless one can rule it out on the grounds of consistency)

    • In the case of Galileo, there are several interesting cases. First, “eppur si muove!” Curiously, the first known record of this supposed utterance comes from a painting done right after Galileo’s death, approximately 10 years after the trial. It doesn’t appear in print until 124 years after the trial. In such a case, I think the term ‘myth’ fits.

      Regarding the Leaning Tower of Pisa, we can say for sure that others performed the experiment before Galileo allegedly did (for example, Giuseppe Moletti and Simon Stevin). Certain apparent discrepancies in the Galileo account were largely laid to rest when Settle and Miklich redid the experiment in front of a camera. “Engines of Our Ingenuity”, no. 166, has a nice description. Galileo never claimed himself, in so many words, to have performed the drop. The story first appears in the posthumous biography by his assistant, Viviani. Viviani’s bio is regarded as not completely reliable for various reasons.

      Among recent historians, you’ll find a spread of opinions. Heilbronn is skeptical. Wootton in The Invention of Science splits the difference: “Viviani was probably right to say that Galileo performed this experiment,… But there is absolutely no evidence, other than Viviani’s account much later, to suggest that crowds gathered to watch Galileo’s early experiments.”

      Finally, in the early part of the 20th century it became conventional historical wisdom (largely thanks to Koyré) to doubt that Galileo had performed almost any of his iconic experiments (e.g., the inclined planes). This extreme revisionist viewpoint was decisively refuted by a two-pronged attack. Thomas Settle and James MacLachlan each repeated some of the experiments, showing that doubts based on “internal” evidence were unfounded. And Stillman Drake went back to hitherto unpublished manuscripts, finding positive documentation.

      Even so, it must be acknowledged (to paraphrase MacLachlan) that Galileo had real experiments, imaginary experiments, and thought experiments, and he did not always clearly distinguish which was which.

      A few refs:

      [1] An Experiment in the History of Science, T. B. Settle, Science, 1961, 133, p.19-23.
      [2] Galileo’s Experimental Confirmation of Horizontal Inertia: Unpublished Manuscripts (Galileo Gleanings XXII), Stillman Drake, Isis 64(3) p.290-305.
      [3] A Test of an “Imaginary” Experiment of Galileo’s, James MacLachlan, Isis 64(3) p. 374-379.
      [4] Experimenting in the History of Science, James MacLachlan, Isis 89(1) p.90-92.

    • C M Graney

      Cormac sez: “So my approach to these science stories is to state that there is no evidence to support a story if there is none, but to leave the possibility that it happened open (unless one can rule it out on the grounds of consistency)”
      ———————————————
      I like that idea at least for teaching. Somewhere I read that Galileo’s mother helped him make telescopes. I’ve never been able to find that again, but it seems somewhat likely …
      https://books.google.com/books?id=v6LLBgAAQBAJ&pg=PA58 (Galileo’s Telescope)
      … and students find it an entertaining idea, so I will relay the story with the caveat that it may well be a myth.

      • laura

        That’s such a good book. It’s amazing that Galileo research can be still be so fresh after so many decades of it.

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  9. C M Graney

    Hey, there is a book out that uses this subject as its title: Newton’s Apple and Other Myths about Science, by Numbers & Kampourakis (Harvard U Press, 2015).

  10. I have the book Galileo’s telescope sitting on a shelf, had forgotten about it…nice one Chris!
    Not sure I like the sound of the Harvard book, sounds a bit definitive…

  11. Jeb

    ” It doesn’t appear in print until 124 years after the trial. In such a case, I think the term ‘myth’ fits.”

    Its a myth because its historically contingent?

    • @Jeb: Or perhaps ‘legend, i.e.:

      a traditional story sometimes popularly regarded as historical but unauthenticated

      the dictionary.com entry for ‘myth’ offers:

      a traditional or legendary story, usually concerning some being or hero or event, with or without a determinable basis of fact or a natural explanation…

      Key point: there may or not be a kernel of truth behind the eppur si muove story, but we’ll never know. At least we can be pretty sure Galileo didn’t proclaim it loudly to the inquisitors!

      Heilbron’s bio Galileo may be cited as an instance of cormac’s complaint. Heibron writes:

      Galileo rose without muttering eppur si muove (“still it moves”) and returned, shattered, to the Medici palace.

      No doubt Heilbron’s time machine revealed to him what Galileo may or may not have muttered under his breath. Or maybe greensight…

      Of course one is inclined to be skeptical. The lack of any contemporary written records corroborating the story speaks against it. Galileo’s disciple Viviani does not include the story in his bio. The scene in the painting is definitely false. Anyway, if true, how did this report come down to us? Galileo would have had to tell someone. Staircase wit? Pure fabrication? Who knows.

      I’m afraid I don’t understand what you mean by ‘historically contingent’. Stephen Gould used to use this term to emphasize that things could have turned out very differently: rewind the tape of life and replay evolution, and intelligent life might not be here. But that doesn’t seem to be your meaning…

      • Jeb

        I’m afraid I don’t understand what you mean by ‘historically contingent’

        Occurring or existing only in certain circumstances.It has a determinable historical context.

        Myths are more often than not timeless entities with no sense of history. The spectrum is fuzzy though between myth and legend.

        These are certainly H.O.S. myth’s.

      • Jeb

        p.s Michael. Try and be more clear.

        If I say “I believe in Robin hood” and you say but that’s a myth. I am not going to have a problem with the English it’s correct and the usage is perfectly understandable in this context, I am just going to be insulted as such words are general taken in a pejorative way by believers.

        Its also saying nothing about what my belief in Robin Hood actually is. I may be standing in a suit of armour I have made myself out of tins of baked beans and have an unfortunate disposition to accepting the legend as fact, or I may be dancing sky clad round an oak tree entranced by the myth.

        H.O.S seems like my friends trip to Egypt the asked the owner of a camel what its name was he replied Michael Jackson they then asked what the name of the Donkey was. Oddly it was called Michael Jackson as well. When they asked why they both had the same name. The owners response was “In Egypt all animals are called Michael Jackson.”

  12. Jeb

    Thony. This took me 3 times to read to get the sense of what you are actually saying.

    That is a mix of a. My stupidity. b. I understand the terms differently and they don’t translate well in a different subject area.

    c. I suspect may be related to how I have been taught to read history. In a period where sources are rare and any datable evidence you have, whilst almost certainly retro may tell you nothing about the period it purports to represent but rather a lot about the period it is written in.

    I can’t help looking at the way myth is deployed in H.O.S without getting left with the sense I may be viewing some form of contextual slight of hand that I cannot relate to my understanding of how you read history and place it in historical context.

    Hard to read and make sense, as I am so use to this strict contextualised form of reading history and dealing with single documents with multiple contextual layers as yielding valuable historical data.

  13. Heilbron discusses Viviani’s description of the Pisa experiment in his (Heilbron’s ) biography of Galileo on page 59-60. He doesn’t come down on either side, truth or myth, leaves it open.
    I’m looking forward to seeing what Heilbron sys in the Apples book

    • Heilbron is much more generous towards Viviani’s highly dubious biography than most Galileo experts.

    • Heilbron’s article is titled “That Galileo Publicy Refuted Aristotle’s Conclusions About Motion by Repeated Experiments Made from the Campanile of Pisa”, i.e., that’s the myth. (Also worth reading: ch. 8, “The Leaning Tower”, of David Wootton’s Galileo: Watcher of the Skies; and ch.6, “Jesuits on the Tower”, of Chris Graney’s Setting Aside All Authority, plus Appendix B, which translates Riccioli’s reports on his own tower experiments, with commentary.)

      Heilbron writes:

      There are several reasons for suspecting that Viviani’s story is a myth: No member of the large and literate audience present and shocked seems to have written a word about it. … Nonetheless, much of Viviani’s story can be confirmed if we take it to apply to a group rather than to an individual [i.e., other folks were dropping things from heights at this time]. …

      The reason that none of the putative witnesses to Galileo’s singular performance ever mentioned it is that it did not take place. [Heilbron’s time machine at work again.] In any case, the demonstration would not have been singular. Professors claiming to know and show the truth about motion, including Galileo’s professors when he studied at Pisa, Girolamo Borro (1512-1592) and Francesco Buonamici (1533-1603), frequently threw objects from the windows of their lecture rooms…

      Wootton and Heilbron cover much the same historical material but with different slants; I recommend reading both. Let me quote Wootton on Galileo’s unpublished manuscript “De motu” (c.1590):

      …at first, he tells us, the lighter object moves faster, but then it is overtaken by the heavier object, which reaches the bottom ahead of it. He has, he tells us, repeated this experiment many times.

      This peculiar result lead Koyré and others to conclude Galileo never performed any of these experiments. Wootton writes:

      Unfortunately, Viviani, Cooper, Koyré and the modern physicists who write about high tower experiments share a fundamental misunderstanding …: they think that experiments are straightforward, and that repeating them is unproblematic.

      The consensus these days points the finger at the difficulty of releasing the light and heavy object simultaneously. Borro and other ball droppers of the time (Coresio, Renieri, de Arriaga, Riccioli, Cabeo, …) reported conflicting results, generally at variance with what “should” have happened.

      Summing up,

      (a) There’s no good reason to believe Galileo didn’t do the tower experiment (though maybe not from the campanile).

      (b) He definitely wasn’t the first to do so, and the notion of a spectacular demonstration, Galileo vanquishing the Aristotelians, counts as a refutable myth.

      • (a) Equally there is no good reason to believe that he did

      • @thonyc:

        I disagree with your “equally”: I think Wootton builds a pretty convincing prima facie case that Galileo performed the ball drop, just not in front of a crowd. What is your reason for concluding that he lied in the unpublished De Motu? Unless your default assumption is that Galileo always lied…

        Besides, as David Letterman demonstrated, dropping things from a height is fun!

  14. Hi Michael, thanks for those references – as always, I come away from this blog with several references I’m looking forward to chasing up.
    However, it puzzles me that the experiment should have been that difficult to perform. My understanding is that the principle of ball-dropping experiments was *not* to show that two balls of different weights drop at approximately the same rate – that would be quite difficult to demonstrate experimentally, even without the complicating fact of air resistance (which depends on factors such as shape and material).
    Instead, the aim of ball-dropping experiments in those days was to *disprove* Aristotle’s conjecture, i.e., to show that a very heavy ball doesn’t fall significantly faster than a heavy ball. That’s much easier to establish experimentally and I believe the phenomenon was tested by several people around this time.
    I can’t remember where I first read this (possibly Ernan McMullin’s ‘The Galileo Affair’?) but it makes sense to me

    • aim of ball-dropping experiments in those days was to *disprove* Aristotle’s conjecture…

      Not really. This sort of “experiment as hypothesis testing” model wasn’t well-established at this point, it really takes root around the time of Boyle. (Wootton has a chapter on this in The Invention of Science.) Of course you can find occasional instances earlier. But the scholars at the time entertained a bunch of different ideas about the behavior of falling object (even among Aristotelians); it wasn’t a clean Aristotle vs. the modern viewpoint face-off. It is true that in 1612 Coresio did some ball drops from the Leaning Tower, and claimed the results vindicated Aristotle’s.

      Nowadays we say that speed is independent of weight in a vacuum. But most scholars at that time believed a vacuum was impossible. In fact, Aristotle’s statement of the “speed proportional to weight” rule occurs in the context of his proof of this impossibility. (Heilbron springboards from this to an argument that Aristotle didn’t mean what he plainly wrote, but that’s another topic.)

      Note that Galileo, in “De Motu”, claimed that the lighter object starts faster out the gate, before being passed by the heavier object in a long enough fall. Not until much later, in the context of his mature (and mathematical) ideas on mechanics, did he come round to the modern viewpoint. (Koyré was right about that.)

      Did Galileo try the experiment in Pisa, maybe on one of his nightly rambles with his drinking buddies? With apologies to Thony, “we will probably never know the final truth about the [Leaning Tower of Pisa] story but I for one find it totally plausible [in modified form] and am prepared to give [Galileo] the benefit of the doubt.” However…

      If we’re asking about significant events in the history of science, then Galileo’s ball drop is a myth. If it occurred, it was not the transitional dramatic event as usually depicted. As early as the 6th century CE, John of Philoponus wrote:

      But this [view of Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small…

  15. 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.

    Chandrasekhar discusses this in Newton’s Principia for the Common Reader (p. 2-6). Noteworthy: Newton later wrote that the calculations agreed “pretty nearly”, and in other cases (e.g., his calculation of the speed of sound, his formula for refraction in birefringent crystals) he showed himself quite willing to allow “fudge factors”. In any case, why (asks Chandrasekher and others) didn’t Newton redo the calculation on returning to Cambridge, where he would have had access to the correct data, and obtained good agreement?

    The famous astronomer J.C.Adams has speculated that another factor played a key role. The moon-apple computation depends crucially on the assumption that the attraction of the apple to the earth can be calculated as if all the mass of the earth were concentrated at its center. Not at all obvious, and one of the most difficult calculations in the Principia! Perhaps Newton didn’t feel sure until he’d obtained this result.

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  17. Jeb

    ‘Newton’s Principia for the Common Reader’

    That’s an interesting title. How do you frame a story for the ‘vulgar genius’ would be the late 17th century choice of words?

    ‘Artificially’ is Newtons specific choice of words which seem to hint at retrospective abstraction.

    Newton’s ideas about language and literalism seem relevant here. Surprised its not formed part of the discussion.

    • Chandrasekhar (one of the greatest astrophysicists of the 20th century) wanted to make the mathematical aspects of the Principia more accessible for present day readers. Not the place to go for what used to be called the ‘external’ historical aspects.

      I don’t know which quote from Newton you are referring to (‘Artificially’).

      • Jeb

        Argument with Thomas Burnett on creation and literalism.

        “As to Moses I do not think his description of ye creation either Philosophical or feigned but that he described realities in a language artificially adapted to ye sense of the vulgar.”

        Newtons argument is that Moses description depicts what a ‘vulgar’ observer would note from a human perspective.

      • @Jeb: Ah, OK.

        Chadrasekhar took his title from this quote from Dr Johnson, which he uses as epigraph:

        I rejoice to concur with the common reader; for by the common sense of readers, uncorrupted by literary prejudices, after all the refinements of subtilty and the dogmatism of learning, must be generally decided all claim to poetical honours.

  18. Jeb

    “external’ historical aspects”

    Its a possible ‘internal’ historical aspect I think. Newtons story about apples does not contradict his wider perspectives on the cosmos or his beliefs on how such things should be read.

    • Sure. Chandrasekhar’s book though is extremely ‘internalist’. He wishes only to ease the reader’s path who desires to absorb the Principia in all its technical glory. I don’t think he even mentions the apple story, and “Newton the man” is almost entirely absent from Chandrasekhar’s book.

      • Jeb

        I could understand why his more mythical persona would be absent here, the entrails of the subject are dynamic and varied. I suspect this story is a myth when placed in its context and time.

        “To the source culture a myth by definition is “true”, in that it embodies beliefs, concepts and ways of questioning to make sense of the world.”

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