7 ms·

The ending doesn't quite work, and I'd say neither does the article as a whole really. First, we didn't really forget "greek fire" or "roman concrete" exactly.

The ending doesn't quite work, and I'd say neither does the article as a whole really. First, we didn't really forget "greek fire" or "roman concrete" exactly. We don't know what the formula for "greek fire" was exactly because it wasn't recorded. But in modern times we have an amazing chemistry and can come up with a hundred formulas for napalm -- we just don't know which of those matches "greek fire". Nothing was lost but the association between a formula we almost certainly know and a name. Same goes for roman concrete. We know far more about concrete than the Romans did. We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time. Yes, some buildings are works of art, but many things just have a function to fulfill, which is often temporary. Nobody is sad that the millions of mass-made soviet residential crappy buildings aren't still as good as new. If they were made to a better standard they'd still be ugly cookie cutter things. And I'd say the same goes for the Saturn V. We didn't forget material science or heat shielding. We launch plenty rockets and even landed car sized robots on Mars -- that required excellent understanding of heat shielding. If we had any reason to build a modern copy, we'd use whatever shielding is required, after accounting for modern improved materials. We wouldn't be dumbfounded that the thing melted down on the launch pad. That in the popular consciousness we see the engines without the asbestos covering doesn't really mean much of anything.

taeric 4y ago
I'd say this goes to some odd myth that I see all too often. That if "you do it right," you won't have to do it again. Somehow, superior technique and dedication of past attempts was lost and that modern attempts are doomed to failure. In large, paradoxically to the explanation, because we are better at building things that just barely accomplish their goals. That is, it is an odd blind spot to not realize that "barely exceeding the goal" is often far far harder than over building.
cwkoss 4y ago
I'd be interested in making some concrete objects that can last 1000 years. Could anyone suggest some resources or search terms to learn what 'forever' concrete entails in our modern scientific understanding, and how much more it would cost?
- hexane360 4y ago
  I'm a materials scientist. Part of the problem is "ancient Roman concrete" is the epitome of selection bias. We basically know why it's strong, and can basically recreate it, but it would take a very long period of process optimization and corrosion testing to get a consistent product we're sure has a long lifespan. If you want something to last 1000 years, you may be better off cutting it out of a hard, stable stone (like granite).
  - einpoklum 4y ago
    > a very long period of process optimization and corrosion testing How long? 1 year? 10 years? 100? 1000? If it's not the last option, isn't it worth figuring out?
    - RajT88 4y ago
      Imagine the wonders we could build if we could justify the investment based on the lifetime of the structure. Actually, you don't have to imagine it. Go watch the show, "Peripheral". This idea of long-lasting concrete was actually what I found myself thinking about just last night watching it, in the scenes of future London.
  - cwkoss 4y ago
    Is there a recipe of 'off the shelf' components that could be mixed together by a layperson and have a high likelihood of being an order of magnitude more durable? Or is the tailoring of the mix to the environmental conditions going to be a more significant factor than the components?
    - kragen 4y ago
      Aluminum hydroxide and phosphoric acid, I think, mixed with enough suitable aggregate that it doesn't explode when you mix it. Look up recipes for castable refractory. Refractory materials aren't always more durable at ordinary temperatures — olivine sand in particular will serpentinize if allowed to weather — but many of them are. There are actually lots of artificial materials that weather more slowly than rebar-reinforced portland-cement concrete. But buildings are huge — a small house commonly contains many tons of building materials, and a large building contains thousands of tons — so the overriding consideration for building materials is that they be cheap as dirt. In fact, buildings — then and now — are to a very large extent literally made of dirt. And rocks. Bricks? That's clay, which is a kind of dirt. Mortar? That's sand, which is a kind of dirt, glued together with typically a small amount of ordinary portland cement with an even smaller amount of additives. Drywall? That's gypsum, which is the kind of dirt White Sands National Monument is made out of (as well as, in its mineral form, many stunning ancient Egyptian vases) although a significant amount of modern gypsum is sourced from flue-gas desulfurization. Plaster? That's sand glued together with cooked gypsum, except when it's sand glued together with quicklime, which is made by cooking chalk. And of course adobe is sand glued together with unfired clay. The issue is that costs that seem totally reasonable when you're dealing with gram or kilogram quantities of a material become totally unmanageable when you need a hundred tonnes of it. You can use glass, wood, or steel (the cheapest metal) in more modest amounts, but they generally can't replace OPC. So, there's a pretty short list of materials that are both strong enough and cheap enough to use as building cements, and which can additionally be synthesized on a building site between grains of sand (as opposed to, say, in a furnace isolated for oxygen, or at 500°). You have: · the above gypsum, quicklime, ordinary portland cement ("OPC"), and unfired clay; · tar (asphalt); · geopolymer cements (milled metakaolin polymerized with waterglass); · waterglass itself; · Sorel cement (magnesium oxychloride); · magnesium oxysulfate; · calcium aluminates; and · the phosphates of aluminum, magnesium, and occasionally calcium or even zinc. Of these, some have worse weathering properties than OPC: unfired clay, Sorel cement, magnesium oxysulfate, and (if cured improperly, in a famous nationwide disaster in Spain a few decades ago which wasn't discovered for years) calcium aluminates. But there are all kinds of extremely stable materials that would last much, much longer than concrete in the weather, but which are just too expensive to make buildings out of, or which nobody knows how to make big enough pieces of. Soda-lime glass (though foamed glass and fiberglass have uses), aluminum, titanium, aluminum bronze, epoxy "granite", gold, silver, polytetrafluorethylene, sapphire, yttria-stabilized zirconia, yttria, carborundum, silicon, the rubber used for car tires, and so on.
einpoklum 4y ago
> We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time Unfortunately... 1. There's no "we". i.e. the entities choosing concrete mixtures and other construction technology do not typically share interests with the people / organizations which inhabit the buildings, except in some very abstract roundabout sense. Which is part of the reason why 2. Concrete construction is usually not engineered to last even a few centuries, let alone "forever". In fact, it is often so poorly engineered (or one might argue: misengineered) that it won't last even a single century, or less than that. Because the principle of costing less money tends to be taken all the way to the point of just barely passing regulatory constraints. 3. ... and those regulatory constraints are often quite lacking. I live in Israel, and a constructor is not even required to guarantee that their building will not-collapse beyond 7 years' time. 4. Actually, a lot of the mass-made soviet-era residential buildings are very well made and almost as good as new (well, considering how they often weren't so great when new). This depends on the specific country, region, period of construction etc.
jcranmer 4y ago
In chemistry in general, a lot of times, minute impurities can have a massive role on the properties of materials (this is especially apparent in food, were flavors are basically entirely defined by chemicals found in ppm quantity). Modern process control essentially works by having the needed and acceptable impurities measured in precise amounts, and relying on chemists and metallurgists to monitor how these impurities come about, but this kind of control has only really been possible for a century or maybe two. In more ancient times, the process control instead basically relied on "get your ingredients from this well/mine/whatever". So while we actually have a decent idea of what Greek fire is (it's a kind of napalm), we don't have any way of knowing what their actual source of naphtha was, so we don't know what the precise impurities that gave it its best kick were. (I'll also opine that there were probably several different formulas in use, and we may be ascribing properties of different kinds of Greek fire to the same one, which would mean that the search for "the" formula for Greek fire could only ever be a failure.)
- mjhay 4y ago
  The real secret to Greek fire was the Byzantine's unusually advanced "siphon," which heated the mixture in a pressure vessel to allow it to spray fairly long distances. The main use was on ships of course, but there was also a man-portable flamethrower version, which is quite strange to think about someone in AD 900 wielding. This ship-borne version only worked in calm conditions, otherwise fireships were just as likely to set themselves on fire. However, it did do pretty well in the sheltered Sea of Marmara around Constantinople. The fireships probably saved the empire from the Caliphate during the 719 siege of Constantinople by destroying the much large Muslim fleet. That occurred at a nadir of Byzantine power and the height of Caliphate power. Western Eurasian history would have looked very different if the Caliphate got control of the Bosporus then, as opposed to the Turks 700 years later.
- ivanhoe 4y ago
  Yes, exactly, the same story is with the Damascus steel. We now know that the secret to it, beside the cool look, was that it contained many carbon nanotubes in steel that greatly improved the performance of the blade. That was achieved by a combination of special properties of the iron ore (supposedly sourced from somewhere in India) and the technology itself that got lost over the time. Of course, modern steel is way better and we now actually understand the tech behind the carbon nanotubes, but the old masters were achieving it all by simply conducting many, many experiments.
areoform 4y ago
Author here, based on my reading of your comment, I think we're talking at cross purposes. Your comment seems to be about how these technologies aren't useful for us in the present. AFAICT, it doesn't dispute that the knowledge was lost. An additional interpretation is that you're interpreting my writing as being from someone who thinks that "the Romans clearly built it better" etc. That's not the point I'm making. Yes, we have napalm and recipes for it. Yes, we have digital computers that are incalculably better than the Antikythera mechanism. Yes, we can trivially manufacture better concrete. And that's amazing, for us today, but how much better would it have been if we hadn't forgotten about these technologies in the first place and had continued to improve on them? Heron of Alexandria described building steam engines, what if we had continued to experiment on them for over 2k years? Where would we be now? The loss in knowledge doesn't matter (as much) anymore in the present, but it has held us back, measurably so. For a thousand years, between the Antikythera mechanism and a few hundred years ago, we somehow lost their equivalent of Kepler's laws, some version of calculus, precision machining, mechanical computing etc. For over a thousand years, we have no records of anyone producing devices that approached or surpassed its capabilities. What if the knowledge behind that device hadn't been lost and we were 1k years further along into our understanding of mathematics and computing? That's the point here. The point is that those technologies were exceptional at their time, but were still lost, and we are poorer for it, because it took away hundreds of years of erstwhile progress that could have been made had we remembered and kept building on them. Happy to hear how I could make the ending better though!
- FpUser 4y ago
  >"The point is that those technologies were exceptional at their time, but were still lost, and we are poorer for it, because it took away hundreds of years of erstwhile progress that could have been made had we remembered and kept building on them." I agree with you point. On the other hand I think if we did not forget anything and kept improving while still having medieval views we might have had exterminated ourselves already.
- kragen 4y ago
  I really enjoyed the post, even though I wasn't clear what part was fictional and what part was truthful. You might be interested in Lucio Russo's book The Forgotten Revolution. He describes how the Hellenistic scientific and technical culture which gave us Heron's aeolipile, Greek fire, the Antikythera mechanism, Archimedes' method of exhaustion, Eratosthenes' measurement of the Earth's size, Eucid's axiomatization of geometry, etc.†, was lost. Basically what happens was that when centers of science like Syracuse and Alexandria were conquered by the pre-scientific Romans, the philosophers who weren't massacred were dispersed to the four winds, preserving their knowledge in foreign lands if at all. In later generations, Christian fanatics lynched Hypatia and threw down the Egyptian temples, extinguishing the millennia-long knowledge of hieroglyphics. Russo reaches some conclusions that aren't generally accepted, but much of the history he reviews in the book is uncontroversial, if little-known — but starkly horrifying. It wasn't a gradual process of forgetting, but a series of genocidal catastrophes. Similar processes obliterated the House of Wisdom in Baghdad, the Maya codices, the khipu, and in our own time most of the world's languages and folklore, much of the Timbuktu libraries, the Afghan relics of early Buddhism, and the collections of the archaeological museums in Iraq. ______ † I have omitted Roman cement and the separation of gold from silver because I don't have any reason to believe they came from the Hellenistic world.
wnevets 4y ago
> Same goes for roman concrete. We know far more about concrete than the Romans did. We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time. Yes, some buildings are works of art, but many things just have a function to fulfill, which is often temporary. Nobody is sad that the millions of mass-made soviet residential crappy buildings aren't still as good as new. If they were made to a better standard they'd still be ugly cookie cutter things. Practical Engineering has a good video on Roman concrete https://www.youtube.com/watch?v=qL0BB2PRY7k https://www.youtube.com/watch?v=qL0BB2PRY7k
deleted 4y ago
[deleted]
thrown_22 4y ago
>Nobody is sad that the millions of mass-made soviet residential crappy buildings aren't still as good as new. If they were made to a better standard they'd still be ugly cookie cutter things. Yet still better than US suburbia.

taeric 4y ago

I'd say this goes to some odd myth that I see all too often. That if "you do it right," you won't have to do it again. Somehow, superior technique and dedication of past attempts was lost and that modern attempts are doomed to failure. In large, paradoxically to the explanation, because we are better at building things that just barely accomplish their goals. That is, it is an odd blind spot to not realize that "barely exceeding the goal" is often far far harder than over building.

cwkoss 4y ago

I'd be interested in making some concrete objects that can last 1000 years. Could anyone suggest some resources or search terms to learn what 'forever' concrete entails in our modern scientific understanding, and how much more it would cost?

hexane360 4y ago
I'm a materials scientist. Part of the problem is "ancient Roman concrete" is the epitome of selection bias. We basically know why it's strong, and can basically recreate it, but it would take a very long period of process optimization and corrosion testing to get a consistent product we're sure has a long lifespan. If you want something to last 1000 years, you may be better off cutting it out of a hard, stable stone (like granite).
- einpoklum 4y ago
  > a very long period of process optimization and corrosion testing How long? 1 year? 10 years? 100? 1000? If it's not the last option, isn't it worth figuring out?
  - RajT88 4y ago
    Imagine the wonders we could build if we could justify the investment based on the lifetime of the structure. Actually, you don't have to imagine it. Go watch the show, "Peripheral". This idea of long-lasting concrete was actually what I found myself thinking about just last night watching it, in the scenes of future London.
- cwkoss 4y ago
  Is there a recipe of 'off the shelf' components that could be mixed together by a layperson and have a high likelihood of being an order of magnitude more durable? Or is the tailoring of the mix to the environmental conditions going to be a more significant factor than the components?
  - kragen 4y ago
    Aluminum hydroxide and phosphoric acid, I think, mixed with enough suitable aggregate that it doesn't explode when you mix it. Look up recipes for castable refractory. Refractory materials aren't always more durable at ordinary temperatures — olivine sand in particular will serpentinize if allowed to weather — but many of them are. There are actually lots of artificial materials that weather more slowly than rebar-reinforced portland-cement concrete. But buildings are huge — a small house commonly contains many tons of building materials, and a large building contains thousands of tons — so the overriding consideration for building materials is that they be cheap as dirt. In fact, buildings — then and now — are to a very large extent literally made of dirt. And rocks. Bricks? That's clay, which is a kind of dirt. Mortar? That's sand, which is a kind of dirt, glued together with typically a small amount of ordinary portland cement with an even smaller amount of additives. Drywall? That's gypsum, which is the kind of dirt White Sands National Monument is made out of (as well as, in its mineral form, many stunning ancient Egyptian vases) although a significant amount of modern gypsum is sourced from flue-gas desulfurization. Plaster? That's sand glued together with cooked gypsum, except when it's sand glued together with quicklime, which is made by cooking chalk. And of course adobe is sand glued together with unfired clay. The issue is that costs that seem totally reasonable when you're dealing with gram or kilogram quantities of a material become totally unmanageable when you need a hundred tonnes of it. You can use glass, wood, or steel (the cheapest metal) in more modest amounts, but they generally can't replace OPC. So, there's a pretty short list of materials that are both strong enough and cheap enough to use as building cements, and which can additionally be synthesized on a building site between grains of sand (as opposed to, say, in a furnace isolated for oxygen, or at 500°). You have: · the above gypsum, quicklime, ordinary portland cement ("OPC"), and unfired clay; · tar (asphalt); · geopolymer cements (milled metakaolin polymerized with waterglass); · waterglass itself; · Sorel cement (magnesium oxychloride); · magnesium oxysulfate; · calcium aluminates; and · the phosphates of aluminum, magnesium, and occasionally calcium or even zinc. Of these, some have worse weathering properties than OPC: unfired clay, Sorel cement, magnesium oxysulfate, and (if cured improperly, in a famous nationwide disaster in Spain a few decades ago which wasn't discovered for years) calcium aluminates. But there are all kinds of extremely stable materials that would last much, much longer than concrete in the weather, but which are just too expensive to make buildings out of, or which nobody knows how to make big enough pieces of. Soda-lime glass (though foamed glass and fiberglass have uses), aluminum, titanium, aluminum bronze, epoxy "granite", gold, silver, polytetrafluorethylene, sapphire, yttria-stabilized zirconia, yttria, carborundum, silicon, the rubber used for car tires, and so on.

einpoklum 4y ago

> We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time Unfortunately... 1. There's no "we". i.e. the entities choosing concrete mixtures and other construction technology do not typically share interests with the people / organizations which inhabit the buildings, except in some very abstract roundabout sense. Which is part of the reason why 2. Concrete construction is usually not engineered to last even a few centuries, let alone "forever". In fact, it is often so poorly engineered (or one might argue: misengineered) that it won't last even a single century, or less than that. Because the principle of costing less money tends to be taken all the way to the point of just barely passing regulatory constraints. 3. ... and those regulatory constraints are often quite lacking. I live in Israel, and a constructor is not even required to guarantee that their building will not-collapse beyond 7 years' time. 4. Actually, a lot of the mass-made soviet-era residential buildings are very well made and almost as good as new (well, considering how they often weren't so great when new). This depends on the specific country, region, period of construction etc.

jcranmer 4y ago

In chemistry in general, a lot of times, minute impurities can have a massive role on the properties of materials (this is especially apparent in food, were flavors are basically entirely defined by chemicals found in ppm quantity). Modern process control essentially works by having the needed and acceptable impurities measured in precise amounts, and relying on chemists and metallurgists to monitor how these impurities come about, but this kind of control has only really been possible for a century or maybe two. In more ancient times, the process control instead basically relied on "get your ingredients from this well/mine/whatever". So while we actually have a decent idea of what Greek fire is (it's a kind of napalm), we don't have any way of knowing what their actual source of naphtha was, so we don't know what the precise impurities that gave it its best kick were. (I'll also opine that there were probably several different formulas in use, and we may be ascribing properties of different kinds of Greek fire to the same one, which would mean that the search for "the" formula for Greek fire could only ever be a failure.)

mjhay 4y ago
The real secret to Greek fire was the Byzantine's unusually advanced "siphon," which heated the mixture in a pressure vessel to allow it to spray fairly long distances. The main use was on ships of course, but there was also a man-portable flamethrower version, which is quite strange to think about someone in AD 900 wielding. This ship-borne version only worked in calm conditions, otherwise fireships were just as likely to set themselves on fire. However, it did do pretty well in the sheltered Sea of Marmara around Constantinople. The fireships probably saved the empire from the Caliphate during the 719 siege of Constantinople by destroying the much large Muslim fleet. That occurred at a nadir of Byzantine power and the height of Caliphate power. Western Eurasian history would have looked very different if the Caliphate got control of the Bosporus then, as opposed to the Turks 700 years later.
ivanhoe 4y ago
Yes, exactly, the same story is with the Damascus steel. We now know that the secret to it, beside the cool look, was that it contained many carbon nanotubes in steel that greatly improved the performance of the blade. That was achieved by a combination of special properties of the iron ore (supposedly sourced from somewhere in India) and the technology itself that got lost over the time. Of course, modern steel is way better and we now actually understand the tech behind the carbon nanotubes, but the old masters were achieving it all by simply conducting many, many experiments.

areoform 4y ago

Author here, based on my reading of your comment, I think we're talking at cross purposes. Your comment seems to be about how these technologies aren't useful for us in the present. AFAICT, it doesn't dispute that the knowledge was lost. An additional interpretation is that you're interpreting my writing as being from someone who thinks that "the Romans clearly built it better" etc. That's not the point I'm making. Yes, we have napalm and recipes for it. Yes, we have digital computers that are incalculably better than the Antikythera mechanism. Yes, we can trivially manufacture better concrete. And that's amazing, for us today, but how much better would it have been if we hadn't forgotten about these technologies in the first place and had continued to improve on them? Heron of Alexandria described building steam engines, what if we had continued to experiment on them for over 2k years? Where would we be now? The loss in knowledge doesn't matter (as much) anymore in the present, but it has held us back, measurably so. For a thousand years, between the Antikythera mechanism and a few hundred years ago, we somehow lost their equivalent of Kepler's laws, some version of calculus, precision machining, mechanical computing etc. For over a thousand years, we have no records of anyone producing devices that approached or surpassed its capabilities. What if the knowledge behind that device hadn't been lost and we were 1k years further along into our understanding of mathematics and computing? That's the point here. The point is that those technologies were exceptional at their time, but were still lost, and we are poorer for it, because it took away hundreds of years of erstwhile progress that could have been made had we remembered and kept building on them. Happy to hear how I could make the ending better though!

FpUser 4y ago
>"The point is that those technologies were exceptional at their time, but were still lost, and we are poorer for it, because it took away hundreds of years of erstwhile progress that could have been made had we remembered and kept building on them." I agree with you point. On the other hand I think if we did not forget anything and kept improving while still having medieval views we might have had exterminated ourselves already.
kragen 4y ago
I really enjoyed the post, even though I wasn't clear what part was fictional and what part was truthful. You might be interested in Lucio Russo's book The Forgotten Revolution. He describes how the Hellenistic scientific and technical culture which gave us Heron's aeolipile, Greek fire, the Antikythera mechanism, Archimedes' method of exhaustion, Eratosthenes' measurement of the Earth's size, Eucid's axiomatization of geometry, etc.†, was lost. Basically what happens was that when centers of science like Syracuse and Alexandria were conquered by the pre-scientific Romans, the philosophers who weren't massacred were dispersed to the four winds, preserving their knowledge in foreign lands if at all. In later generations, Christian fanatics lynched Hypatia and threw down the Egyptian temples, extinguishing the millennia-long knowledge of hieroglyphics. Russo reaches some conclusions that aren't generally accepted, but much of the history he reviews in the book is uncontroversial, if little-known — but starkly horrifying. It wasn't a gradual process of forgetting, but a series of genocidal catastrophes. Similar processes obliterated the House of Wisdom in Baghdad, the Maya codices, the khipu, and in our own time most of the world's languages and folklore, much of the Timbuktu libraries, the Afghan relics of early Buddhism, and the collections of the archaeological museums in Iraq. ______ † I have omitted Roman cement and the separation of gold from silver because I don't have any reason to believe they came from the Hellenistic world.

wnevets 4y ago

> Same goes for roman concrete. We know far more about concrete than the Romans did. We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time. Yes, some buildings are works of art, but many things just have a function to fulfill, which is often temporary. Nobody is sad that the millions of mass-made soviet residential crappy buildings aren't still as good as new. If they were made to a better standard they'd still be ugly cookie cutter things. Practical Engineering has a good video on Roman concrete https://www.youtube.com/watch?v=qL0BB2PRY7k https://www.youtube.com/watch?v=qL0BB2PRY7k

deleted 4y ago

[deleted]

thrown_22 4y ago

>Nobody is sad that the millions of mass-made soviet residential crappy buildings aren't still as good as new. If they were made to a better standard they'd still be ugly cookie cutter things. Yet still better than US suburbia.