The great New Horizons Pluto fly-by has occurred. We have our mottling, our iron colors, and large patches of light and dark which will keep astrogeologists like Jonathan active and excited for months and years to come. I wanted to make sure you all had a chance to see the NASA reports on the Pluto surface, and Pluto’s moon Charon, whose surface shows every sign of a very active interior.
I am also happy to announce that I have just launched a new Kickstarter campaign, to support the production of two new CDs of my music. “Stories and Stone” is a companion album to “Sundown: Whispers of Ragnarok” containing variant arrangements of my Viking music, plus new recordings of my anthem for Space exploration and human progress “Somebody Will”. “Trickster and King” will be the first album recorded by myself and my singing partner Lauren Schiller as the duo “Sassafrass: Trickster and King”. The whole first album and half of the second are finished and streaming online, so please listen and enjoy. And if you enjoy, please consider supporting the Kickstarter, and spread the word about it (NOW OVER – it was a great success, THANK YOU! Hear the music here). Much of the goal of this campaign is to raise money so I can afford to hire help, including my assistant Mack who works with me here on Ex Urbe and with other projects. I am having more and more demands on my time as teaching and research at Chicago become more intense, and especially as the release of my novels approaches, and the more help I can hire the more time I can devote to Ex Urbe posts and other creative projects. So if you’ve been wondering if there’s a “tip jar” or some other way you can support Ex Urbe, this is a great way, as is spreading the word about the campaign.
The finished album, to be released in August:
And the second album still in progress:
Somebody Will with guitar:
It’s hard to pick a single favorite track, but if I had to it is probably Hearthfire in five parts, with guitar performed by my (wonderful and Space exploration-championing!) editor Patrick Nielsen Hayden:
The first CD should ship in September, with an instant digital download when the Kickstarter finishes in August.
Meanwhile, to split the difference between Viking music and Pluto, I recently had the good luck of a daytime flight over Greenland in beautiful weather, so please enjoy this photo essay on the wild and icy geology of our own little planet, and the frosty habitat of our native Jotuns and trolls:
A week from today, the NASA New Horizons Spacecraft will perform its close flyby of Pluto, beaming back the first color images of our solar system’s last uncharted world (and finally telling the makers of the Celestial Buddies line what color they should make their long-awaited cuddly Pluto). In celebration of the occasion, I have solicited a guest post from my good friend Jonathan Sneed, an astrogeologist/ paleobiologist, currently working as a research technician with the Solar System and Exoplanet Habitability Group here at the University of Chicago. Jonathan studies rocks, and what rocks tell us about how planets and other astronomical bodies form and develop, especially when life gets in the mix. These are the skills we need to predict which planets and other space rocks might have life, or the chemicals necessary to support us as we launch out into the vast and black frontier. Jonathan’s essay offers predictions about what New Horizons might find when it makes its flyby next week, gives a taste of how much photos alone can teach us about the history and potential of Pluto, and offers a glimpse of how astrogeology lets us learn about the celestial stepping stones scattered around us.
When she’s talking about the history of skepticism, our host likes to talk about Pluto, and in particular about the argument that scientists had about it. Shall it be a planet? A dwarf planet? A planetoid? Megarock? Especially large ice cube? In her classroom, Pluto is the enemy of eudaimonia, a didactic example of the stress we experience when our perceptions shift and the maps are all rewritten. She discusses the ways that we use doubt to insulate ourselves against collisions between truth and belief, how the ancient Pyrrhonists found a refuge in uncertainty. It’s all rather grim.
Obviously, I can’t let her be the one to talk about the imminent New Horizons flyby.
It is, after all, a unique moment in human history! For most of us, most of the time, discovery is a kind of communication. You turn to page 57 and look at a full-page spread of the Krebs Cycle, or stop by a street performer on your way to the grocery store and hear real jazz for the first time, or open your RSS feed and read a quote by Sartre, and your world shifts under your feet just a bit. But moments like this are a reminder: there are things that nobody knows, and you have the ability to know them. If you’re willing to admit a little uncertainty, that is.
Over the next few weeks, a great many things will become known about a whole new world. I thought this might be a good opportunity to sketch out some of what you might look for, so that you can participate a little bit more actively in that moment, if you have a mind to do so. The New Horizons craft is outfitted almost entirely with cameras, imagers, and spectrometers of one sort or another, so we’ll have basically one thing to go on: what color is it?
Granted, some of those photons will be well outside the range of the human eye, so I’m using ‘color’ with a certain amount of poetic license. But at the end of the day, it’s a remarkably straightforward little device. We were curious about Pluto, so we looked at it. The atmosphere should be quite visible, and it’s more than thin enough for us to peer through that atmosphere to the solid surface beneath. From there, we’ll see not just the elements that make up pluto, but also the chemical arrangements that they’ve made for themselves and the large shapes and geological formations that have emerged. Are there mountains and valleys? Volcanoes? Some kind of erosional process that cycles and recycles the surface?
And these things, in turn, will tell us more than you might expect. Because we don’t just know what Pluto looks like now; we have a pretty good guess about where it started, and two points make a line.
One of my favorite facts (up there with ‘birds are dinosaurs’) is that the number of mineral types in the universe is increasing at an exponential rate. For a geologist, every day is the most exciting day the universe has ever had! A while back, the first stars and the preposterous forces at work inside them, gave us the first heavy elements and the few mineral grains they can form drifting in interstellar space. Eventually, those first primitive grains clumped together to form rocks and then whole planets, with solid bits and fluid bits and change, and new minerals emerged from that dynamism. The kind of minerals that are only formed when water evaporates into an atmosphere and leaves a residue behind. The kind that are only formed when some kind of fancy-pants self-sustaining carbon-based chemical process decides to secrete a shell for itself. The kind that first come in to being when a state legislature settles on new safety standards for concrete. And so on, accelerating ever onwards.
(Actually, human-created objects don’t technically count as minerals, but this is an arbitrary semantic line. ‘Anthropocite’ is far too wonderful a word to not get used in a scientific journal eventually.)
What this means for Pluto is that, despite the huge variety of things that a (dwarf) planet(oid) might do, the starting ingredients have to be drawn from a set of things that can be cooked by a star and are willing to clump together in space. As to what it did with those things in the four and a half billion years since… well, that’s harder to guess. But here are some of the most important ingredients that might go into your Pluto recipe, drawn straight from the primordial dust itself:
Water ice. Ammonia. Silicates, with a variety of elements thrown in for flavor- potassium, phosphorous, a great many metals. Iron and sulfur compounds, usually bonded with oxygen or mixed in with the silicates. Carbon, doing its crazed carbon dance, probably already forming a few amino acids and alcohols as it falls into the gravity well. Carbon, being less creative, oxidized or in the form of methane. Hydrogen and helium, as much as you like, although those will run away from the world almost as soon as they arrive.
I’ve been careful to emphasize some of the ones that I think are going to be important, so this is isn’t comprehensive. But it’s a lot closer to comprehensive than you’d think. All in all, there are a little more than a hundred different molecules floating around between the stars, a shockingly finite list.
Even more conveniently, we have a category we can use. No, not ‘planet’, alas. The category I am thinking of is ‘Kuiper Object’. On Ex Urbe, categories are a deep and compelling subject in their own right, but for the time being I shall take a narrow and cowardly view. All I mean is that Pluto is quite similar to a lot of other things in the ways we have already measured, and so I wouldn’t be too surprised if it was also similar to those things when we measure new aspects of it.
Kuiper Objects are a fascinating bunch, named by the region just outside Neptune’s orbit. They’re quite icy (some would even float), and they come in a range of exciting colors for the discriminating consumer (gray is common, and red and black are, as always, favorites). There are many things we don’t know about Kuiper objects, but we’ve also had one tantalizing opportunity:
This is a picture of Triton, one of the moons of Neptune, given to us by interstellar traveler and Blind Willie Johnson fan Voyager II. Triton is quite icy, although it would not quite float in water. It comes in a range of exciting colors, primarily gray and red. And it’s going around Neptune in basically the wrong direction, which implies that it fell into Neptune’s gravity well a good deal after planetary formation. It also, for the record, has an atmosphere, surface composition, and density shockingly similar to that which we infer for Pluto. So, there’s that.
A while back, I shared an office with a guy who wrote a thesis about how confusing Kuiper Objects are. He had written an efficient and cutting-edge program that would transform reasonable assumptions into arcane squiggles and crying graduate students. I learned a lot from that guy, especially about the perils of trying to predict the behavior of (dwarf) planet(oid)s given even very simple starting conditions. What happens when you make a very, very large pile of ice and silicates, and then wait for four and a half billion years? What do we expect to see when we take our picture of Pluto? Potentially, a lot of things.
But for any big pile of rocks, there are basically four ways to get the thing to move: sunlight, radiation, gravity, and chemistry. Actually, gravity and radiation make a nice twofer.
The idea is this: shuffle silicate rocks and water ice into a big ball. A lot of the heavier metals mixed in with your silicates are a bit radioactive, so they warm the ice around them into a kind of slush (same reason the Earth is a fluid once you go a few miles down). That’s just enough lubrication to let the heavy stuff fall to the bottom, and the lighter stuff rise to the top- and now we have some density gradients to work with, and maybe even some liquid(ish) water. Even more excitingly, everything in that ball that isn’t easily trapped in mineral form (the nitrogen compounds, the methane, and all those wonderful mad organic molecules) will tend to get squeezed out to the exterior surface, or near it. We call those ‘volatiles’, which is one of those charmingly literal phrases that scientists sometimes use. They explode, is what I’m saying.
Almost certainly, this is the process that first set Pluto in motion. But what happens then, especially on the surface? Once you squirt out all the gasses and form an atmosphere, and expose your wiggly mad carbon to sunlight, what does it do next? Well, here’s where the graduate students start crying, but let’s give it a shot. We’ll start with the most sensible and least speculative feature, giant ice volcanoes.
Ice volcanoes are a good sign of an active world, for the same reason that molten rock volcanoes are on Earth- they have to be refreshed by ongoing tectonic activity. As far as we know, they’re exactly the same kind of structure. At temperatures this low, ice is just another kind of rock, and it takes geological forces to warm that rock up to its melting point and expel it as magma. Except, the magma is water (plus a complicated mix of other volatiles like nitrogen)- so we call it ‘cryomagma’, a truly fabulous word if ever I saw one.
If we’re exceptionally lucky, we’ll see an active volcano during the flyby- on Triton, our closest analogue to Pluto, these eruptions can last for (Earth-) years, so it’s not an unreasonable hope. But even if we don’t, we should be able to find strong evidence that they did happen; look for dark smears in the calderas as frozen nitrogen ‘ash’ falls back to the surface.
Another really important thing to watch out for is the craters. Specifically, there not being any.
Here’s a puzzle for you: how do we date rocks on Mars? If you’re lucky enough to have a rover right there, you can run any number of exciting tests, but it’s a big planet and there aren’t that many rovers. Yet, we have guesses about the age of Olympus Mons and Hellas Planitia. How?
The answer is that Mars is fairly inert- enough so that the craters are more or less permanent fixtures. So if you know how often a meteorite is going to blow a hole in a given area, all you have to do is count the craters and then you have a pretty good measure of how long that surface has been exposed. ‘Pretty good’ means plus or minus 600,000,000 years, granted. But I think it’s a pretty cool trick anyway.
So if we make it to Pluto and it’s covered in craters like Earth’s moon or Mars, then that means Pluto has slowed down a lot in the last few billion years. If, on the other hand, it’s fairly crater-free, then something is busy removing those craters. That smells quite a bit like active tectonics. So: ice volcanoes, or craters, but not both- those tools could give us a pretty good idea of whether there is an active mantle in the subsurface, pushing the outer (nitrogen, methane, ice) crust around and otherwise being interesting.
Only, that mantle would be a fluid made of, among other things, water.
As a species, we’ve gotten very good at looking, so even before New Horizons we knew a few things about the surface of Pluto. Broadly, it has the coloring we expect for a Kuiper Object: grey, black, and red, and is sharply mottled. But what, actually, do these colors mean?
I mentioned sunlight as one of the forces that must move Pluto. Granted, the sun lacks a certain degree of strength at that distance, but in combination with the rotation of the (dwarf) planet(oid), the sun is going to be the primary cause of temperature variations at the surface, far away from all that radioactive rock at the center. As the ice volcanoes have shown us, it’s not so much the absolute temperature that matters, as whether or not that temperature cycles around any interesting phase transitions. And as it happens, there are three (and only three, that I know of) materials in our original Pluto recipe that have an interesting phase transition at Pluto’s surface temperatures: carbon monoxide, methane, and nitrogen.
These can have seasonal rhythms, they can precipitate or frost, and are generally going to provide a lot of the bulk material for all the really interesting chemical reactions at the surface. If the ice of Pluto is as rock on Earth, then these are its water and air.
Nitrogen doesn’t help us with that coloration problem too much, but the other two? Those are interesting. Because the beating heart of both is a bit of carbon, and carbon is flexible enough to explain a great many things and a great many colors. This is the element that gives us black graphite and transparent diamonds, after all. When our carbon molecules are left outside for a few billion years of exposure, through years of those interesting phase transitions, something will change- the carbon will fry in the ultraviolet light. Very, very slowly, and it has to be peeled away from the hydrogen and oxygen first, but it will fry all the same. And as it happens, this can explain both the red and the black against a grey ice background.
These are not, of course, the only explanations for the colors that we see on the surface of Pluto. Red has a classic association with iron oxides (you and Mars are red for the same reason, as it happens), and there is a potential universe out there where the surface of Pluto is rusted. But the world is not very dense, and so this would require a great many odd things- not only that there be no mantle fluidity to pull dense minerals inward, but that some inverse process pulled it away, concentrating that metal on the outer circumference. I can’t think of what that might be. But nonetheless, it could be what reality gives us. The disadvantage of this theory is not that it is impossible, just that it requires a great many things to be true. And so I lean towards an explanation that doesn’t demand further concessions from reality, using only the processes that we already acknowledge on the parts that we started with.
Carbon and Water:
I have done a mean thing. I used cryovolcanics and an analogy to Triton as a way of suggesting that there might still be liquid (or at least slushy) water on Pluto. And then, I invoked a reasonably elegant explanation of Pluto’s mottled coloration to suggest that surface processes are driving chemistry of complex carbon molecules.
You are now thinking about aliens.
Or at least, I assume so. I would be. Not flying saucers or anything out of our drive-through horror shows. No, you’re considering the possibility of some simple microbe, maybe a Plutonian lichen of some sort, with subtle but radical implications for our role in the universe as living things. Then again, maybe not; I spend a lot of time thinking about aliens, so my calibration may be off. But if you were thinking about aliens, I apologize. There are not aliens on Pluto. Definitely not, certainly not. I am at least 95% sure, and even that is rounding down. Probably.
There’s a funny inverse to the eudaimonia of skepticism. If we remember that anything we believe might be false, then we can indeed let go of our beliefs with a certain grace. But if anything might be false, then just think of all the things that might be true! And there’s the danger. Before long, we look up and see the canals on Mars that we hope for, rather than the Vallis Marineris as it actually is.
Every planet and moon that we’ve investigated in this solar system has been utterly unique. These worlds are awesome, and frightening, and alien. Crystal cities on Venus would have been amazing, but they would have been amazing in a very human way- they would have been our fantasy, not an encounter with a genuinely new reality. And in the same way, whatever is really on Pluto, it’s going to be an experience that wasn’t bent to fit our expectations, a thing that nobody knows. It will be wonderful, even though it won’t be life.
Welcome to a new feature here on Ex Urbe — the promoted comment.
From time to time, Ada makes a long substantive chewy comment, which could almost be its own post. Making it into an actual post would take valuable time. The comment is already written and fascinating — but hidden down in a comment thread where many people may not notice it. From now on, when this happens, I will extract it and promote it. I may even go back and do this with some older especially awesome comments. You’ll be able to tell the difference between this and a real post, because it’ll say it’s posted by Bluejo, and not by Exurbe, because it will say “a promoted comment”, and also because it won’t be full of beautiful relevant carefully selected art but will have just one or two pieces of much more random art.
I thoroughly enjoyed reading this new post. As I am reviewing macroeconomics, especially the different variations of Solow Model, I cannot help but link “intellectual technology” with the specific endogenous growth model, which attempts to led the model itself generate technological growth without an exogenous “manna from heaven”. In this model, technology growth is expressed endogenously by the factor capital as “productive externalities”, and individual workers, through “learning by doing,” obtain more “skills” as the capital grows. Of course, the “technology factor” in the model I learned is vaguely defined and does not cover the many definitions and various effects of “intellectual technology” not directly related to economic production.
Your conversation with Michael reminds of me the lectures and seminars I took with you at Texas A&M. By the time I took your Intellectual History from Middle Ages to 17th Century, I have already taken some classes on philosophy. Sadly, my fellow philosophy students and I usually fell into anachronism and criticized early thinkers a bit “unfairly” on many issues. That is why your courses were like a beam of light to me, for I was never aware of the fact that we have different logic, concepts, and definition of words from our predecessors and should hence put those thinkers back into their own historical context.
It seems to me that Prof. Peter E. Gordon’s essay “What is intellectual history’ captures the different angles from which you and Michael construe Machiavelli: Michael seems more like a philosophy/political science student who attempts to examine how and why early thinkers’ ideas work or not work for our society based on our modern definitions, concepts, and logic, thus raising more debates on political philosophy and pushing the progress of philosophical innovation; your role as an intellectual historian requires one to be unattached from our own understanding of ideas and concepts and to be aware of even logic that seems to be rooted in our subconsciousness so that to examine a past thinker fairly without rash judgement. Michael is like the one who attempts to keep building the existing tower upward, while you are examining carefully the foundation below. For me personally, it would be nice to have both of these two different ways of thinking.
I have a question: I have been attempting to read a bit of Karl Marx whenever time allows. He argues that our thinking and ideology are a reflection of our material conditions. If we accept his point of view, would it be useful to connect intellectual history with economic history?
Nahua, I think you have hit it spot on with your discussion of Peter Gordon’s essay. When I worked with him at Harvard (I had the privilege of having him on my committee, as well as being his teaching assistant for a course) I remember being struck by how, even when we were teaching thinkers far outside my usual scope like Heidegger, I found his presentation of them welcoming and approachable despite my lack of background, because he approached them in the same context-focused way that I did, evaluating, not their correctness or not or their applicability to the present, but their roots in their contemporary historical contexts and the reasons why they believed what they believed.
For Marx’s comment that “our thinking and ideology are a reflection of our material conditions” I think it is often very useful to connect intellectual history with economic history, not in a strictly deterministic way, but by considering economic changes as major environmental or enabling factors that facilitate or deter intellectual change and/or the dissemination of new ideas. I already discussed the example of how I think the dissemination of feminism in the 19th century was greatly facilitated by the economic liberation of female labor because of the development of industrial cloth production, more efficient ways of doing laundry, cleaning, cooking etc. Ideas about female equality existed in antiquity. They enjoyed a large surge in conversation and support from the intellectual firebrands of the Enlightenment, through figures like Montesquieu, Voltaire and Wollstonecraft. But mass movements and substantial political changes, like female suffrage, came when the economic shift had occurred. To use the “intellectual technology” concept, the technology existed in antiquity and was revived and refined in the 18th century, but it required economic shifts as well to help reach a state when large portions of the population or whole nations/governments could embrace and employ it.
As I work on Renaissance history, I constantly feel the close relationship between economics and the intellectual world as well. Humanism as I understand it began when Petrarch called for a revival of antiquity. Economics comes into this in two ways. First, the reason he thought a revival of antiquity was so desperately necessary was because Italy had become so politically tumultuous and unstable, and was under such threat of cultural or literal invasion from France–these are the consequences, largely, of economic situations, since Italy’s development of banking and its central position as a trade hub for the Mediterranean had filled its small, vulnerable citystates with incomparable wealth, creating situations where powerful families could feud, small powers could hire large mercenary armies, and every king in Europe wanted to invade Italy for a piece of its plump pie. Then after Petrarch, humanism’s ability to spread and succeed was also economically linked. You can’t have a humanist without books, you just can’t, it’s about reading, studying, correcting and living the classics. But in an era when a book cost as much as a house, and more than a year’s salary for a young schoolmaster, a library required a staggering investment of capital. That required wealthy powers–families or governments–to value humanism and have the resources to spend on it. Powers like the Medici, and Florence’s Republican government, were convinced to spend their money on libraries and humanism because they believed it would bring them glory, strength, respect, legitimacy, the love of the people, that it would improve life, heal their souls, bring peace, and make their names ring in posterity, but they couldn’t have made the investment if they hadn’t had the money to invest, and they wouldn’t have believed humanism could yield so much if not for the particular (and particularly tumultuous) economic situation in which Renaissance Italy found itself.
Yesterday I found myself thinking about the history of the book in this light, and comparing it to some comments I heard a scientist make on a panel about space elevators. We all want a space elevator–then space exploration will become much, much less expensive, everyone can afford satellites, space-dependent technologies will become cheap, and we can have a Moon Base, and a Mars program, and all the space stations we want, and all our kids can have field trips to space (slight exaggeration). To have a space elevator, we need incredibly strong cables, probably produced using nanofibers. Developing nanofibers is expensive. What the engineer pointed out is that he has high hopes for nanofiber devlopment, because nanofibers have the ideal demand pattern for a new technology. A new technology like this has the problem that, even if there are giant economic benefits to it later on, the people who pay for its development need a short-term return on that, which is difficult in the new baby stages of a technology when it’s at its most expensive. (Some of you may remember the West Wing episode where they debate the price of a cancer medication, arguing that producing each pill costs 5 cents so it’s unfair to charge more, to which the rebuttal is that the second pill cost 5 cents, but the first pill cost $300 million in research.) Once nanofiber production becomes cheap, absolutely it will be profitable, but while it’s still in the stage of costing $300 million to produce a few yards of thread, that’s a problem, and can be enough to keep a technology from getting support. One of the ways we work around this as a society today is the university system, which (through a form of patronage) supports researchers and gives them liberty to direct research toward avenues expected to be valuable independent of profit. Another is grant funding, which gives money based on arguments for the merit of a project without expecting to be paid back. A third is NASA, which develops new technologies (like velcro, or pyrex) to achieve a particular project (Moon!), which are then used and reused in society for the benefit of all. But looking at just the private sector, at the odds of a technology getting funding from investors rather than non-profits, what the scientist said is that, for a technology to receive funding, you want it to have a big long-term application which will show that you’ll make a steady profit once you can make lots of the thing, but it needs to also to have a short-term application for which a small number of clients will be prepared to pay an enormous amount, so you can sell it while it still costs $300 million, as well as expecting to sell it when it costs 5 cents. Nanofibers, he said, hit this sweet spot because of two demands. The first is body armor, since it looks like nanofibers can create bullet-proof fabric as light as normal fabric, and if we can do that then governments will certainly pay an enormous amount to get bullet-proof clothing for a head of state and his/her bodyguards, and elite military applications. The second is super-high-end lightweight golf clubs, which may seem like a frivolous thing, but there are people who will pay thousands of dollars for an extremely high end golf club, and that is something nanofibers can profit from even while expensive (super lightweight bicycles for racing also qualify). So nanofibers can depend on the excitement of the specific investors who want the expensive version now, and through their patronage develop toward the ability to produce things cheaply.
In this sense the history of the book, especially in the Renaissance, was very similar to the situation with nanofibers. In the early, manuscript stage when each new book cost the equivalent of $50,000 (very rough estimate), libraries were built and humanism was funded because wealthy people like Niccolo Niccoli and Cosimo de Medici believed that humanist libraries would give them and their home city political power and spiritual benefits, helping them toward Heaven. That convinced them to invest their millions. Their investments then created the libraries which could be used later on by larger populations, and reproduced cheaply through printing once it developed, but printing would not have developed if patrons like them weren’t around to make there be demand for the volume of books printing could produce. It took Petrarch, Niccoli and Cosimo to fund a library which could raise a generation of people who could read the classics before there was enough demand to sell the 300-1500 copies of a classical book that a printing press could print. And, working within current capitalism, it may take governments who really want bullet-proof suit jackets to give us our space elevator, though universities, NASA, and private patronage of civilian space programs are certainly also big factors pushing us forward.
In sum, I would say that economics sometimes sparks the generation of new ideas–as the economically-driven strife Petrarch experienced enabled the birth of humanism–but it also strongly affects how easily or quickly a new idea can disseminate, whether it gets patronage and support, or whether its champions have to spread it without the support of elites, patrons or government. Thus, in any given era, an intellectual historian needs to have a sense of funding patterns and patronage systems, so we can understand how ideas travel, where, and why.
One more thought from last night, or rather a test comparison showing how the concept “intellectual technology” can work. I was thinking about comparing atomism and steel.
Steel is a precursor for building skyscrapers. Despite urban demand, we didn’t get a transition to huge, towering metropoles until the development of good steel which could raise our towers of glittering glass. Of course, steel is not the ONLY precursor of the skyscraper–it also requires tempered glass, etc. And it isn’t the only way to build skyscrapers, you can use titanium, or nanotech, but you are very unlikely to get either of those things without going through steel first. Having steel does not guarantee that your society will have skyscrapers. Ancient Rome had steel. In the Middle Ages Europe lost it (though pretty-much everywhere except Europe still had steel). When steel came back in the Renaissance it still didn’t lead immediately to skyscrapers, it required many other developments first, and steel had to combine with other things, including social changes (growth of big cities). But when we look at the history of city development, studying steel is extremely important because the advent of steel-frame construction is a very important phase, and a central enabling factor for the development of modern cities.
My Lucretius book looks at the relationship between atomism and atheism in the same way that this analysis looks at steel and skyscrapers. Atomism was around for a long time, went away, came back, etc. And you can have non-atomic atheism, we have lots of it now. But atomism, as the first fully-developed mechanical model of the working of Nature (the first not dependent on God/gods to make the world work) was, in my opinion, one of the factors that you needed to combine with other developments to reach a situation in which an intellectual could combine mechanical models of nature with skepticism with other factors to develop the first fully functional atheistic model of the world. It’s one of the big factors we have to trace to ask “Why did atheism become a major interlocutor in the history of thought when it did, and not before or after?” just as tracing steel helps us answer “Why did skyscrapers start being built when they did?” There had almost certainly been atheisms before and independent of atomism (just as you can make really tall things, like pyramids or cliff-face cities, without steel-frame construction) but it was rare, and didn’t have the infrastructural repeatability necessary to let it become widespread. Modern atheists don’t use Epicurus, they more frequently use Darwin, just as modern skyscrapers use titanium, but the history of skyscrapers becomes clear when we study the history of steel. Just so, the history of atheism becomes much clearer when we study atomism. Of course, we now use steel for lots of things that aren’t skyscrapers (satellite approaching Pluto!), and similarly atomism has lots of non-atheist applications, but we associate atomism a lot with atheism, just as we think a lot about “towers of glass and steel” and usually think less about the steel bolts in our chairs or the steel spoons we eat with. All applications of steel, or epicuranism, can be worth studying, but skyscrapers/ atheism will never stop being one of the biggest and most interesting, at least in terms of how they changed the face of our modern world. And finally, while minority of buildings are skyscrapers, and a minority of contemporary people are atheists, the study of both is broadly useful because the presence of both in the lives of everyone is a defining factor in our current world.