Gulliver's Travels, Isaac Newton, and Flying Saucers

Jonathan Swift (1667-1745) anonymously published his four-part novel, "Gulliver's Travels" in 1726, at the end of a visit to London.

Most people know it for the chapters set in Liliput (where Gulliver is a giant compared to the natives), and maybe also Brobdingnag (where the natives are giants, and it's Gulliver who's considered tiny). It's a scathing social and political farce, where Gulliver's visits to other societies show different systems of government and different social orders. While in Liliput, Gulliver is considered a dangerous giant, and treats the tiny locals with callous indifference. In Brobdingnag it's Gulliver who's overlooked and considered unimportant, so the extent that he's caged and treated as a pet.

But there's also a chapter (at the end) where he visits the Houyhnhnms, a race of talking horses that Gulliver considers entirely superior to humans, who regard the local ape-decended species (the "Yahoos") as loud, primitive, warlike and violent. After living with the Houyhnhnms, Gulliver comes to see all humans as Yahoos.

And for the science fiction fans, there's a chapter about a giant flying saucer.

Really, there is. The third section of the story has Gulliver being rescued by a scientifically advanced society, based on the flying island of Laputa. The city is built on a four-and-a-half-mile-wide concave circular plate topped by buildings, along with four lakes for collecting rainwater, surrounding an astronomical observatory built into a central shaft, that also includes the levitating mechanism. It is, quite literally, a "castle in the air" inhabited by scientists.

Laputa rules over a kingdom (Balnibari), whose borders are defined by the limits of a naturally-occurring geological magnetic anomaly, and the flying city is held aloft by a giant tiltable magnet, held in place by unbreakable "adamant" cage that is of a single piece with the city's baseplate. The city rises and falls and gets sideways propulsion by adjusting the alignment of the magnet.
The flying city is a local scientific superpower, and the king's response to rogue cities below is to steer the saucer above the rebel stronghold and set it down, crushing them.

Unfortunately, I'm not aware of any illustrated editions of "Gulliver's Travels" where the illustrators tackled Laputa. Perhaps the idea was just too freaky for them. If they had, they'd have probably ended up drawing something that looked like the mothership in Spielberg's 1977 "Close Encounters" film.

The other notable thing about Swift's flying city of Laputa is that although it is ordered along entirely scientific principles, its (highly quotable) math-and-music obsessed inhabitants at the Academy of Lagado are buffoons, working on crazy and expensive projects such as the extraction of sunlight from cucumbers, constantly begging for more money for their projects as the society below them decays – it's a fairly small step to suspect that Swift was taking the mickey out of the esteemed Royal Society (then headed by Isaac Newton), and it's even been claimed that Swift emphasised this by basing all of the Lagado projects on specific Royal Society papers.

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This raises an intriguing question: did Swift actually meet Newton?
It seems that when Swift had been in London in 1710, he'd been visiting a woman called Catherine Barton. Barton was Newton's half-niece, and one of the few people that Newton was close to. Barton wasn't just some peripheral nominal relative of Newton, she'd actually moved to London and moved in with Newton in about 1696 (about the time he got his job at the Mint), and kept house for him.

If Catherine Barton was living with Isaac Newton and being visited by Jonathan Swift, then Isaac Newton would have cast a rather large shadow over Swift's consciousness, even if he hadn't been /the/ Isaac Newton.

And if that wasn't enough, there was also the subject of Money.
Immediately before "Gulliver's Travels", Swift's celebrity was based on his having anonymously written and published the Drapier's Letters in ~1724-25, a series of pamphlets railing against the coining of copper currency for Ireland, which led to a widespread boycott of the new coins in Ireland and their withdrawal. One of Swift's (many) objections was an allegation that the coins were of poor quality - Newton, as Master of the Mint since the mid-1690's, had to get involved and do an assay, and reported that the allegation wasn't true.
Newton was known for his tetchiness, but Swift in particular had a reputation for being gratuitously and grossly offensive. I've got an old C19th copy of "Gulliver's Travels" that describes Swift as having "more than any other man who ever wrote in English, a liking for saying nasty things", and blames this for Swift's repeated ruination of his own career prospects. Apparently Swift wanted to be a bishop, but even as a returning hero of the Irish people, when the people in charge actually met him, it became clear that this wasn't going to happen. That edition of "Gulliver's" mentions "the deadly agitations of his private life" as being something that the C19th reader might want to enquire about in later life – but whatever this unmentionable personal train wreck was, it doesn't seem to have made it as far as his Wikipedia page.

So perhaps the two wouldn't have wanted to meet each other, especially since they both cared about the same woman. Having the the brittle, acidic, reserved Newton in the same room as the extrovert, scandalous, offensive Swift might not have been a good idea, and the fact that they both had strong ideas about currency would probably just have made things worse.

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The young, exiled Francois Marie Arouet ("Voltaire") was also in London around this time, and seems to have been rather keen on Catherine, too.
Voltaire later went on to write "Micromegas" (1752), a short satire that appears to have been partly inspired by "Gulliver", in which a pair of giant aliens from Sirius and Saturn arrive on Earth and meet up with and ridicule a bunch of tiny Earth philosophers (with the exception of one guy who is a follower of John Locke). That's John Locke, the guy whose writings seem to have influenced the American Declaration of Independence, not John Locke, the character from "Lost" (a TV series about a strange island with a natural magnetic anomaly).

Another link between Voltaire's story and Swift's is that both throw in a little casual detail (known to the fictional Laputans and alien scientists) that the Mars was "known" to have two moons, and it seems natural to assume that Voltaire probably borrowed this detail from Swift. In fact, Mars has got two moons – Phobos and Deimos – but they didn't get discovered for real until 1877. That earned both writers an astronomical "credit": the only two named features on the smaller of the two satellites are a pair of adjacent craters, named "Voltaire" and "Swift".

After he'd given up on the brilliant Catherine and snuck back to France, Voltaire shacked up, long-term, with another brilliant woman obsessed with Newton, Émilie du Châtelet, who as well as being a serious respected researcher in her own right, translated, produced and reworked (with her comments) the French edition of Newton's Principia.

To the C18th coffee-house intelligentsia, a mix of physicists, philosophers and political theorists, this was a time of revolution and restructuring (not to mention a certain amount of fluidity over people's living arrangements). England had recently undergone a rapid turnover of rulers, flip-flopping from Monarchy to Republic, and back to Monarchy again, then Monarchy chosen by Parliament. Cromwell had kicked out Charles I, Charles II and James II had taken over from Cromwell, and the Glorious Revolution had then given Paliament the right to choose the monarch, which brought in William and Mary, and which they then exercised again in the Act of Settlement to shunt the succession to Anne, who'd then died, too. The Acts of Union in 1707 had then finally united England and Scotland as a single kingdom. In the politics of 1726 England there were various entrenched factions with specific ideas about how the country ought to be run, and by whom, but there was no guarantee that any one particular group would obtain ultimate control.

There was a sense that this was where we decided what the future was going to look like. Was it going to be run by royalists or republicans? Theologians or scientists? Committees or street campaigners? "Gulliver's Travels" tapped into an appetite for exploring possibilities, and showing how different systems failed. Voltaire's later story got a charge out of lampooning philosophers because at the time, philosophy was reckoned to matter. These guys were potentially the architects of the new society.

"Gulliver" can be seen as parody of how people brought up in different political and philosophical systems can believe that their own way of seeing the world and the correct order of things is right and proper, even when outsiders can see that it's ludicrous, and was, in a real sense, revolutionary. Together with a surrounding body of other philosophical and campaign literature, it helped to set up the context for debate that made the French Revolution and the American War of Independence seem possible to the people who risked their lives to make those things happen.

It's not just a kid's story about a shipwrecked guy being tied down with string by little tiny people.

Isaac Newton and E=mc²

The history of the idea of mass-energy conversion is a slightly murky one. Textbooks and lecturers find it convenient to say that Albert Einstein was the first person to suggest that mass and energy were interchangeable, but really ... he wasn't. That's a handy piece of educational fiction. It ain't so.

By 1905, a number of researchers were reckoned to be close to the E=mc² result. The basic argument went something like this: imagine a mirrored cavity embedded in a piece of material, containing a trapped light-complex, in equilibrium with its container. The radiation pressure of the trapped light within the container is the same in all directions. But if the container and its trapped electromagnetic (EM) energy are now viewed by a different observer who reckons that the container is "moving", then that observer will assign different Doppler-shifted energies and radiation pressures to different parts of the light-complex: The forward-aimed components now get assigned greater energy and momentum than the rearward-aimed components, and the overall momentum of the complex no longer cancels out - the container's nominal motion gives the trapped light an overall momentum that points in the direction of motion.
So the EM contents of the moving container appear to contribute additional momentum to it, as if it contains a speck of matter rather than EM energy. If we aren't allowed to look inside the container, we might not be able to tell whether it contained EM energy or real matter, and by working out how much energy it takes to reproduce the external effects associated with a given amount of mass, we end up with a very short equation for the conversion factor between rest mass and rest energy. That (if we calculate it correctly) is E=mc².

However, it seems that Einstein's competitors either didn't calculate the conversion ratio properly, or failed to come out and suggest in print that this wasn't merely an apparent conversion of mass and energy, but The Real Thing. Einstein did both, and earned the credit.

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If we want to go back further, to find an older example of the idea of "interconvertibility" in a major English-language physics text by a famous author, all we have to do is open a copy of Isaac Newton's "Opticks" [Babson archives]/[1717 edition.pdf], and flip to the "Queries" section at the back. The relevant section is Query 30:

Qu.30: Are not gross Bodies and Light convertible into one another, and may not Bodies receive much of their Activity from the Particles of Light which enter their Composition?...
The changing of Bodies into Light, and Light into Bodies, is very conformable to the Course of Nature, which seems delighted with Transmutations.

I've quoted this at the start of Chapter 2 of the "Relativity..." book ("Gravity, Energy and Mass"), which goes through some of these arguments in more detail (with the help of some pictures).

Traditionally, at this point in the discussion, a physicist will interrupt and say something like,

"Okay, perhaps Newton had the idea, but we weren't able to calculate the specific relationship until we had special relativity. Einstein used Lorentz's relationships in his calculations rather than Newtonian physics, so so E=mc² is clearly specific to Einstein's physics."

But that's not true either. It's correct that Einstein originally presented E=mc² in the context of his new "special" theory, but if he'd done the momentum calculations with the same degree of care using "olde" Newtonian emission theory, he'd have gotten the same result (with slightly less working). In fact, we can construct a continuum of hypothetical theories whose relationships differ by Lorentzlike ratios, and all of them generate E=mc². Turns out, E=mc² is a general result. I've put the details of the "Newtonian optics" argument into the book's "Appendices" section, as "Calculations 2"

So, while some physics histories present Einstein's discovery of E=mc² in 1905 as a triumph of the scientific method, the reality seems to be that the equation's discovery is marked by a sequence of earlier human failures going back two hundred years.
To start with, Newton couldn't calculate E=mc² because he'd gotten the relationship between energy and frequency upside down, and assumed (reasonably but wrongly) that the "bigger", redder wavelengths of light carried more energy and momentum for a given amplitude, rather than less ("The Newtonian Catastrophe", chapter 3). Newton lived 'til 1727, and then his his successors still couldn't calculate E=mc², because they trusted Newton to have gotten it right. If you were an English physicist, suggesting that Newton might have made a mistake was heresy. Towards the end of the century (1783), John Michell used Newton's arguments to calculate the gravitational wavelength-shifting of light, but he was still citing Newton's writing and using the old bad "inverted" relationships. Defending Newton from criticism was now a matter of national pride, and in 1772, Joseph Priestley's History of Optics had been cheerfully ridiculing the mental capacity of those poor retards in Europe who were so behind the times that they actually still thought that light was a wave! Antagonism between the two sets of researchers meant that the Newtonian group couldn't admit the possibility of major error.

The next couple of decades saw Europe shaken up by the French Revolution, and then Continental physics really began to hit its stride. Newton's mistake had generated a bad prediction that light should travel more quickly through glass than air, and when Continental experimenters started using new technology to measure lightspeeds, they were able to show, quite conclusively (and perhaps slightly gleefully), that this wasn't the case. As we got to the mid-C19th, work by Christian Doppler and others meant that we were now quite sure how to calculate the effect of velocity on light for any given model, but instead of going back and correcting Newton's error, Newton's supporters slunk off with their tails between their legs, and did their best to rewrite physics history so that later English-speaking physics students hopefully wouldn't realise just how dumb they'd been.

The latter part of the C19th was then "lost", too. Although we now had plenty of expert wave theorists, lightwaves were now generally reckoned to propagate through some sort of aetheric medium, and there was no agreed set of governing principles defining what that medium's properties ought to be. The credibility of the older Newtonian principles concerning the behaviour of light (such as the idea that the behaviour of matter and light ought to obey a single set of underlying rules) were now widely considered to be "damaged goods", and the proliferation of aether models meant that we now had a bewildering array of competing predictions for exactly how the properties of light ought to be affected by motion. There were just too many damned versions for us to be able to do these sorts of calculations confidently, and be sure that our results meant anything.

That state of affairs lasted until the early Twentieth Century.

This is where Einstein came onto the scene. Einstein had three advantages over most other contemporary theorists when it came to deriving E=mc² - he was a fan of the idea that the principle of relativity should apply to light, he was definite about the set of equations that he wanted to use, and he was (apparently) blissfully unaware of almost all of the previous two centuries of political bickering on the subject (probably helped in part by his habit, as a student, of not bothering to turn up for lectures). So Einstein was able to come to the problem "fresh", without a lot of preconceptions. He'd already tinkered with emission theory, recognised some of the problems, and had then latched onto Lorentzian electrodynamics, and decided that this was The Future.

In 1905, he published his "reimagining" of Lorentzian electrodynamics , which took the characteristics of Lorentz's relativistic aether and deleted the "physical medium" aspect as unnecessary. According to Einstein in 1905, aether was irrelevant to the problem - all that was required to generate the Lorentzian relationships was the principle of relativity and an assumption about lightspeeds. These two postulates were then sufficient to generate all of Lorentz's important math.

And then (as a very short followup paper) ... if the Lorentzian relationships in the previous paper were correct, internal energy imparted mass to bodies, according to the relationship E=mc².
At this point, Einstein was on a roll, and he was looking forwards rather than backwards ... he didn't really have much motivation to point out that, if the relationships in his earlier paper were wrong, and we reverted to the previous relativistic calculations for light, we still got E=mc². Pointing that out was a job for peer review and outside commentators, but almost no-one noticed.

We then coasted though another century, without much to suggest that anyone had connected the dots and understood the broader context for what Einstein had done and how it really related to Newton's earlier work. Right into the 1990s, students were still being told that E=mc² was unique to special relativity, and that the fact that atom bombs worked was ample evidence that no other system of equations could be right. Those claims weren't scientifically or mathematically correct, and weren't researched, but everyone seemed to believe them. Some people wrote research papers and entire books on the history of E=mc², and still somehow managed not to mention the Newtonian connection.

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Not everybody missed it. The Sandman series by Neil Gaiman quotes and cites the key section in "Opticks" and points out its its significance. But Sandman isn't a book on theoretical physics, it's an illustrated fantasy graphic novel. So what we appear to have here is a subject where some people who write university textbooks seem to be doing rather less background research and fact-checking than some people who write comicbooks.

I feel that this is an unhappy situation. But it seems to explain a lot about why theoretical physics is in its current state.