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.
topics: history, philosophy, technology
created: 13 June 2016; modified: 11 Jan 2019; status: finished; confidence: highly likely; importance: 2


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.

Isaac Newton, in his , 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.

Excerpts

David Gregory summarizes some 1694 comments by Newton, then 52, about the stability of the solar system (from of The Correspondence of Isaac Newton (Turnbull 1961), 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 , the now-aged (83) reveals considerably more details of his speculations about the true system of the world to his nephw-inlaw :

…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 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 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 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 needles had been ma de (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 Jupiter 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 a magical process like ‘fusion’ or else regular resupply? pace Lord Kelvin’s ), but is still very alien. Angels in charge of comets! Things really were different then.

It would make for an excellent retro SF or 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 would like to write a followup to or , or Scott Alexander & ?)

Mistakes

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/ 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. 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 (): 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.

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 , 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, because I came across a version of it in Lucretius’s :

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 a little 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), but it’s the same idea: given the fact of recent progress in apparently easy low-hanging fruit like composing epics or inventing needles, this implies either that humanity is itself of recent origin (in some sense) or that progress only began recently for no good reason. But and the latter is absurd, so they reject it and accept the other possibility. The claims of 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 .)

From our perspective, the pace of progress in Newton’s day—never mind Lucretius 1700 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 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], needles [and thread], etc”.↩︎