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Newton’s System of the World and Comets

Isaac Newton’s cosmology apparently involved regular apocalypses caused by comets overstoking the furnace of the Sun and the repopulation of the Solar System by new intelligent species. He supports this speculation with an interestingly-incorrect anthropic argument.

Isaac Newton published few of his works, and only those he considered perfect after long delays. This leaves his system the world, as described in the Principia and elsewhere, incomplete, and many questions simply unaddressed, like the fate of the Sun or role of comets. But in 2 conversations with an admirer and his nephew, the elderly Newton sketched out the rest of his cosmogony.

According to Newton, the solar system is not stable and must be adjusted by angels; the Sun does not burn perpetually, but comets regularly fuel the Sun; and the final result is that humanity will be extinguished by a particularly large comet causing the sun to flare up, and requiring intelligent alien beings to arise on other planets or their moons. He further gives an anthropic argument: one reason we know that intelligent races regularly go extinct is that humanity itself arose only recently, as demonstrated by the recent innovations in every field, inconsistent with any belief that human beings have existed for hundreds of thousands or millions of years.

This is all interestingly wrong, particularly the anthropic argument. That Newton found it so absurd to imagine humanity existing for millions of years but only recently undergoing exponential improvements in technology demonstrates how counterintuitive and extraordinary the Industrial & Scientific Revolutions were.

Boldly Sir Isaac Newton, in his Principia, laid out the laws of celestial motion—but didn’t solve many other questions about the Solar system: how was the Solar System created and how old was it, how did God keep it stable rather than chaotic, how long would the Sun burn until its fire went out, what is the fate of humanity, and what the role of comets?

What did he make of those problems? Newton declined to commit his beliefs to publication, but an interesting summary survives thanks to a relative of his.


David Gregory summarizes some 1694 comments by Newton, then 52, about the stability of the solar system (from pg365–371 of The Correspondence of Isaac Newton (Turnbull1961), Volume III):

[Newton says] that a continual miracle is needed to prevent the Sun and the fixed stars from rushing together through gravity: that the great eccentricity in Comets in directions both different from and contrary to the planets indicates a divine hand: and implies that the Comets are destined for a use other than that of the planets. The Satellites of Jupiter and Saturn can take the places of the Earth, Venus, Mars if they are destroyed, and be held in reserve for a new Creation.

In the later 1724 “Account of a conversation between Newton and Conduitt”, the now-aged (83) Isaac Newton reveals considerably more details of his speculations about the true system of the world to his nephew-in-law John Conduitt:

…there was a sort of revolution in the heavenly bodies that the vapours & light emitted by the sun which had their sediment as water & other matter had gathered themselves by degrees into a body & attracted more matter from the planets & at last made a secondary planet (viz. one of those that go round another planet) & then by gathering to them & attracting more matter became a primary planet, & then by increasing still became a comet which after certain revolutions by coming nearer & nearer the sun had all its volatile parts condensed & became a matter fit to recruit & replenish the sun…as a fagot would this fire if put into it…

…that would probably be the effect of the comet in 1680 sooner or later…perhaps have 5 or 6 revolutions more first, but whenever it did it would so much increase the heat of the sun that this earth would be burnt & no animals in this earth could live.1

…He seemed to doubt whether there were not intelligent beings superior to us who superintended these revolutions of the heavenly bodies by the direction of the supreme being—

He seemed to be very clearly of opinion that the inhabitants of this earth were of a short date & alleged as one reason for that opinion that all arts as letters long ships printing—needle &c2 were discovered within the memory of History which could not have happened if the world had been eternal

…when I asked him how this earth could have been repeopled if ever it had undergone the same fate it was threatened with hereafter by the Comet of 1680, he answered that required the power of a creator—

…[I] told him I thought he owned there what wee had been talking about—viz. that the Comet would drop into the sun, & that fixed stars were recruited & replenished by Comets when they Dropt into them, & consequently the sun would be recruited too & asked him, why he would not own as freely what he thought of the sun as well as what he thought of the fixed stars—he said that concerned us more, & laughing added he had said enough for people to know his meaning—

The System of the World

Newton explains fully “what he had often hinted to me before” to Conduitt: celestial bodies grow by accretion due to gravity, and as they grow bigger, pass from moons to planets to even larger (!) comets. Comets, in looping past the Sun, slowly become cooked. The Sun would go out due to its constant conflagration, but fortunately, it is constantly renewed and powered by the fresh fuel provided it by comets passing nearby. “Intelligent beings” (angels?) oversee this whole process of regular fueling of the sun, but unfortunately the Great Comet of 1680 passed so close to the Sun that it seems likely that it will soon fall directly into the sun, rather than feeding it a small measure of fuel.

With an enormous quantity of fuel abruptly dumped into the Sun instead of dispensed over eons, it will flare up like a bonfire and quite likely roast the Earth (like a red supergiant might, incidentally), killing everything on it. This possibly happens regularly, since humanity seems to have been created only recently, as evidenced by how recently such major innovations like printing or steel needles had been made (contradicting any supposition humanity had existed for more than a few thousand years). After this, possibly God would renew creation by repopulating instead the moons of Saturn or Jupiter3 which would have escaped the inferno relatively intact due to their distance.

This is an interesting cosmology and has a lot of sense to it (how does the Sun burn more than a long time without some completely unknown and nigh-magical process we might call ‘fusion’ or else regular resupply? pace Lord Kelvin’s well-reasoned & acute but wrong comments on the Sun’s age, comets as inadequate fuel sources, & refuting Evolution4), but is still very alien. Angels in charge of comets! Things really were different then.

It would make for an excellent retro SF or steampunk novel, if nothing else. (Naturally, the heroes would be recruited by the angels to help deal with the crisis of the return of Newton’s comet… Perhaps Ted Chiang would like to write a followup to “Exhalation” or “Seventy Two Letters”, or Scott Alexander & Unsong?)


It’s also interesting for why it’s wrong: Newton needs comets to be at least planet-sized, because comets are too rare to be plausibly fuel sources for the Sun if they’re small (they wouldn’t dump enough fuel in to keep combustion going for another few decades/centuries until the next big comet, as astronomical records since the Babylonians constrained big comets to be highly infrequent), but of course they’re very small; if they were planet-sized, you’d think they’d severely disturb planetary orbital calculations, so was the existing astronomical data insufficiently precise to prove the absence of such orbital disturbances or was there some other issue?

The anthropic/mediocrity argument for the short duration of the human race is also wrong, since we know anatomically modern & presumably equally intelligent humans have been around for at least 50,000 years at this point, with human civilization developing only in the last small fraction. What’s particularly interesting about his argument is that if he had made it at a truly randomly chosen point in human history (picked at random from, say, 50,000 BC to 2019 AD), then he would have correctly concluded the opposite, that the human race was ancient, due to the lack of any discernible progress in the recent past (‘progress’ having not yet been invented): in fact, he could only have made this argument in a tiny window between the start of the Scientific/Industrial Revolution and the archaeological/geological/evolutionary proof of mankind’s antiquity starting around the 1800s, so maybe 400 years or 0.4 millennia; he had to have the bad luck to be born into that exact 0.8% historical window for the argument from progress to be convincing & wrong! Remarkable.

Newton was not the only one to notice how unusual a period he lived in; Girolamo Cardano noted something similar ~150 years prior in his 1575 autobiography The Book Of My Life, although since it is in a chapter subheaded “Concerning Natural Though Rare Circumstancs of My Own Life”5, he appears to have bitten the bullet of believing himself lucky. The Italian astrologer Tommaso Campanella, writing a 1602 utopian tract while imprisoned for organizing a Spanish revolution to bring about a new age (which he would die believing imminent), finishes with his European interlocutor saying, “Oh, if you knew what our astrologers say of the coming age, and of our age, that has in it more history within 100 years than all the world had in 4,000 years before! of the wonderful inventions of printing and guns, and the use of the magnet, and how it all comes of Mercury, Mars, the Moon, and the Scorpion!”6

I wonder if Newton’s belief that he was merely rediscovering what the ancients like the Chaldeans or King Solomon knew, a conviction closely connected to his Biblical & alchemical research, is connected to this ‘recent progress’ argument, as it could also be taken as evidence for humanity existing for a long time but in constant cycles of rise and fall, implying the possibility of many cycles of knowledge being esoterically encoded into the most ancient writings & ideologies?

If I have seen further it is by standing on the sholders [sic] of Giants.

Interestingly, it seems the ‘short human history’ argument is not original to Newton, and has been used elsewhere to defend the eternity of the world (a position made tricky if indeed humans only came into existence recently) because I came across a version of it in Lucretius’s On the Nature of Things:7

Moreover, if heaven and earth never had a beginning or birth, but have existed from everlasting, why have there not been other poets to sing of other events prior to the Theban war and the tragedy of Troy? Why have so many heroic deeds so often been buried in oblivion, instead of flowering somewhere, implanted in eternal memorials of fame? The true explanation, in my judgment, is that our world is in its youth: it was not created long ago, but is of comparatively recent origin. That is why at the present time some arts are still being refined, still being developed. This age has seen many improvements in shipbuilding; it is not long since musicians first molded melodious tunes; our system of philosophy too is a recent invention, and I myself am found to be the very first with the ability to expound it in the language of my country [Latin].

If by chance you believe that all these same things happened before, but that the races of human beings perished in a great conflagration, or that their cities were razed by a mighty convulsion of the world, or that rivers, rapacious after unremitting rains, inundated the earth and submerged towns, there is all the more necessity for you to admit defeat and acknowledge that heaven and earth are destined to be destroyed.

Lucretius’s argument is not quite the same, as he equivocates on whether intelligent species/humans go in cycles of creation & destruction (which appears to be Newton’s take) or if the universe is simply of recent date (which would, incidentally, be consistent with a literalist Biblical take in which recent progress is because the world & humanity were created only recently, per Genesis); his goal is to convince the reader that Heaven & Earth are not eternal and will perish, and it is unimportant if the world is young or old with cycles. But the latter is clearly the same idea as Newton’s: given the fact of recent progress in (apparently) low-hanging fruit like composing epics or inventing needles, this implies either that ‘contemporary’ human civilization is itself of recent origin (in some sense) or that progress only began recently for no good reason. But “one man’s modus ponens is another man’s modus tollens” and the latter is absurd, so they reject it and accept the other possibility.

Another argument, defending Lucretius on different grounds, is provided by Machiavelli in his Discourses on Livy II.5 (“The Changes Of Religion And Of Languages, Together With The Occurrence Of Deluges And Pestilences, Destroy The Record Of Things”) in which he defends eternalism by arguing that we should not expect any trustworthy records because political/religious movements regularly destroy all ancient things (eg. the Burning of books and burying of scholars) every few thousand years, and then particularly extreme disasters wipe out humans every few tens to hundreds of thousands of years:

To those philosophers who maintain that the world has existed from eternity, we might reply, that, if it were really of such antiquity, there would reasonably be some record beyond 5000 years, were it not that we see how the records of time are destroyed by various causes, some being the acts of men and some of Heaven. Those that are the acts of men are the changes of religion and of language; for when a new sect springs up, that is to say a new religion, the first effort is (by way of asserting itself and gaining influence) to destroy the old or existing one; and when it happens that the founders of the new religion speak a different language, then the destruction of the old religion is easily effected. This we know from observing the proceedings of the Christians against the heathen religion; for they destroyed all its institutions and all its ceremonies, and effaced all record of the ancient theology. It is true that they did not succeed in destroying entirely the record of the glorious deeds of the illustrious men of the ancient creed, for they were forced to keep up the Latin language by the necessity of writing their new laws in that tongue; but if they could have written them in a new language (bearing in mind their other persecutions), there would have been no record whatever left of preceding events. Whoever reads the proceedings of St. Gregory, and of the other heads of the Christian religion, will see with what obstinacy they persecuted all ancient memorials, burning the works of the historians and of the poets, destroying the statues and images and despoiling everything else that gave but an indication of antiquity. So that, if they had added a new language to this persecution, everything relating to previous events would in a very short time have been sunk in oblivion.

It is reasonable to suppose that what the Christians practised towards the Pagans, these practised in like manner upon their predecessors. And as the religions changed 2 or 3 times in 6000 years, all memory of the things done before that time was lost; and if nevertheless some vestiges of it remain, they are regarded as fabulous, and are believed by no one; as is the case with the history of Diodorus Siculus, who gives an account of some 40 or 50,000 years, yet is generally looked upon as being mendacious, and I believe with justice.

As to causes produced by Heaven, they are such as destroy the human race, and reduce the inhabitants of some parts of the world to a very few in number; such as pestilence, famine, or inundations.8 Of this the latter are the most important, partly because they are most universal, and partly because the few that escape are chiefly ignorant mountaineers, who, having no knowledge of antiquity themselves, cannot transmit any to posterity. And should there be amongst those who escape any that have such knowledge, they conceal or pervert it in their own fashion, for the purpose of gaining influence and reputation; so that there remains to their successors only just so much as they were disposed to write, and no more. And that such inundations, pestilences, and famines occur cannot be doubted, both because all history is full of accounts of them, and because we see the effects of them in the oblivion of things, and also because it seems reasonable that they should occur.

This is a reasonable argument by Machiavelli: it is true that religions attempt to erase and recycle their predecessors and if only through neglect, assure their disappearance9, and it is also true that occasional catastrophes like pandemics can depopulate regions & end civilizations (eg. the New World, or the Black Plague). Greo-Roman or Renaissance-era philosophers may have believed in vast mathematical and religious knowledge belonging to the Egyptians or ancient Greeks and that known philosophical schools were but the tattered scraps of the original Golden Age—yet, they were still wrong. There were no civilizations 50,000 years ago, and more than enough survives of pre-Christian or pre-Islamic civilizations for us to understand them.

The claims of gradualism and evolution—that the observed geography and biology arose only incrementally over hypothesized periods of millions or even billions of years, such lengths being necessary to account for the human-observed short-term stasis of species or geography—would have doubtless struck them as even more absurd. Who could accept a theory like “after billions of years, humans evolved, but then nothing of any importance happened for hundreds of thousands or millions of years, until then everything started happening in the past 10,000 years at an ever-accelerating pace”? Nevertheless… (Here we have a situation similar to that of heliocentrism and the problem of the parallax, of being wrong for the right reasons. Connell2011 notes the irony: particularly in the Renaissance, these theories of an eternal world emerged as part of the awakening of critical thought about theological dogmas like Creationism—but it was the dogmas which were right about the universe being of a finite age.)

From our perspective, the pace of progress in Newton’s day—never mind Lucretius1700 years prior—was agonizingly slow and near-invisible, but to Newton and his contemporaries, it must have appeared rapid, even more rapid than for Lucretius.

This offers a little twist on the “Singularity” idea: apparently people have always been able to see progress as rapid in the right time periods, and they are not wrong to! We would not be too impressed at several centuries with merely some shipbuilding improvements or a long philosophy poem written in Latin, and we are only modestly impressed by needles or printing presses. Human history, starting sometime in the Neolithic, is a giant exponential, which just keeps going up. What seemed startlingly rapid at one point may seem agonizingly slow viewed from a later standpoint.

  1. How this can be reconciled with his beliefs in a Second Coming of Jesus or the various dates/time-ranges he attempted to estimate for the Apocalypse or even the occurrence of an Apocalypse & Second Coming of Jesus, I do not know.↩︎

  2. This is a confusing sentence and the scan is not available to check, but I interpret Conduitt as meaning “that all arts, such as [alphabetic] letters, long [ocean-going] ships, printing [presses], [steel] needles [and thread], etc”.↩︎

  3. Newton was not the only astronomer to suspect intelligent life on the Jovian moons. In April 1610, Johannes Kepler wrote to Galileo of his Starry Messenger:

    …Meanwhile I cannot refrain from contributing this additional feature to the unorthodox aspects of your findings. It is not improbable, I must point out,344 that there are inhabitants not only on the moon but on Jupiter too or (as was delightfully remarked at a recent gathering of certain philosophers345) that those areas are now being unveiled for the first time. But as soon as somebody demonstrates the art of flying, settlers from our species of man will not be lacking. Who would once have thought that the crossing of the wide ocean was calmer and safer346 than of the narrow Adriatic Sea, Baltic Sea, or English Channel? Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse. Therefore, for the sake of those who, as it were, will presently be on hand to attempt this voyage, let us establish the astronomy, Galileo, you of Jupiter, and me of the moon.

    1. This statement was mistakenly transferred from Kepler to Galileo by Bryk (p. 347). Galileo did not attribute inhabitants to the moon and to Jupiter, despite Bryk.

    2. In the letter of April 19 (NE X, 336:606) Kepler said instead: “at Wackher’s dinner table” (in mensa nostri Vackherii).

    3. In Vespucci’s “Four Voyages” the first two crossings were calm and safe. Perhaps Kepler did not read as far as the third voyage (“On those days [of the Atlantic crossing] we experienced worse weather than anyone had ever suffered at sea before”) and the fourth voyage (“A fierce and bitter storm arose, and a contrary wind and adverse weather prevailed”); in Waldseemüller, “Introduction to Cosmography,” fol. e2v, Bv.

  4. We could note that Kelvin recognized the problem of fusion; his argument is essentially, “there are only two known natural processes which could heat the Sun at its measured power output, burning of something like coal or the heat of collision from its original formation; both of these would power the sun for on the order of tens of millions of years; therefore, the sun is around tens of millions of years old.”

    It logically follows—by modus tollens—that as soon as geologists and others began establishing that the Earth is not tens of millions of years old, but hundreds or thousands, that there must be a third unknown natural process to explain the Sun’s impossible longevity. And if the Sun can tap into this process of creating energy, why not men? And if the energy can be created at least as fast as the Sun creates it, then it can probably be created fast enough to have military applications..↩︎

  5. Pg189–1990, chapter 41, Stoner1930:

    Among the extraordinary, though quite natural circumstances of my life, the first and most unusual is that I was born in this century in which the whole world became known; whereas the ancients were familiar with but little more than a third part of it. On the one hand, we explore america…Besides all these, towards the East under the Antarctic…as well as Japan, Binarchia…all discoveries sure to give rise to great and calamitous events in order that a just distribution of them may be maintained.

    …[M]eanwhile we shall rejoice as in a flower-filled meadow. For what is more amazing than pyrotechnics? Or than the fiery bolts man has invented so much more destructive than the lightning of the gods?

    Nor of thee, O Great Compass, will I be silent, for thou dost guide us over boundless seas, through gloomy nights, through the wild storms seafarers dread, and through the pathless wilderness.

    The fourth marvel is the invention of the typographic art, a work of man’s hands, and the discovery of his wit—a rival, forsooth, of the wonders wrought by divine intelligence. What lack we yet unless it be the taking of Heaven by storm! Oh, the madness of men to give heed to vanity rather than the fundamental things of life! Oh, what arrogant poverty of intellectual humility not to be moved to wonder! But to return to my theme [concerning the avenging of my son]…

  6. Francis Bacon’s New Atlantis is similarly utopian and in the “Salomon’s House” section, describes many scientific achievements like statues raised to Columbus or “your monk that was the inventor of ordnance and of gunpowder”, but also many ancient achievements like the invention of silk, which attribution they know “all these by more certain tradition than you have.” So it’s unclear to me if New Atlantis includes an explicit claim to recent acceleration of progress. Similarly, in his famous Four Great Inventions (Book 1, §CXXIX of Novum Organum), Bacon says his apologetics for invention are to “quicken the industry and rouse and kindle the zeal of others”, and he describes the inventions so as to “observe the force and virtue and consequences of discoveries” and the importance of pursuing inventions to benefit all humanity forever; he notes that their “origin, though recent, is obscure and inglorious” mostly to heighten the contrast between the smallness of the input & greatness of the output, and doesn’t make any claims about acceleration I can immediately see (aside from predicting that following his recommendations for greater empiricism, “the art of discovery may advance as discoveries advance”).↩︎

  7. Alternate translation of the passage, from A. E. Stallings’s 2007 verse translation (Book V “Cosmos and Civilization”, lines 324–344):

    …Besides, were there no birthday for the earth and for the sky,
    If they’d existed always for eternity, then why
    Is it in epic song the ancient poets never employ
    Events before the Seven Against Thebes or Fall of Troy?
    Why have so many deeds of men just dropped into the gloom
    And grafted on the eternal monuments of fame no bloom?

    But this world’s still a fresh and newborn thing, I hold it so:
    The genesis of the world was not so very long ago.
    And that’s why, in the arts, we’re making great strides to this day—
    Ships were recently much improved. Nor was it far away
    In the mists of Time musicians learned to make mellifluous song.
    These very revelations about the universe are young,
    And I myself the first to put them in our mother tongue.
    But if you think these things were all invented before, and lost
    When earlier races of men were burnt up in a holocaust,
    Or a mighty convulsion of the earth laid all their cities low,
    Or relentless downpours made the hungry rivers overflow
    And inundate the land, engulfing towns beneath their spate,
    All the more reason you must admit defeat—you demonstrate
    Yourself that earth and sky are doomed to die!

  8. Note Machiavelli’s Euhemerism here.↩︎

  9. As almost happened to Lucretius (2 or 3 surviving copies) and Livy’s Ab Urbe Condita Libri (only a quarter survives); and as Machiavelli notes later on, the Romans were unkind to their Etruscan predecessors, who remain mysterious. (We could also note that modern population genetics has shown that near-total population replacement is quite common throughout deep history.)↩︎

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