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This isn't specific to computer or software engineering, of course. There are still Roman aqueducts in use that were engineered thousands of years ago.

by smeyer 11y ago

mekael 11y ago
I'm fascinated by things like the aqueducts. The skill to make them is something i can never comprehend.
- grayclhn 11y ago
  Overengineeing doesn't take nearly as much skill as you'd think. It would be pretty easy for any of us to design a wall that, if left alone, would last for thousands of years.
  - kragen 11y ago
    You would think, but often things fail in unexpected ways. https://en.wikipedia.org/wiki/Zinc_pest https://en.wikipedia.org/wiki/Zinc_pest is destroying thousands of die-cast zinc-alloy toys from the 1930s to 1950s. Zinc alloys are pretty corrosion-resistant, so this was a surprise. https://en.wikipedia.org/wiki/Cellulose_acetate_film#Decay_and_the_.22vinegar_syndrome.22 https://en.wikipedia.org/wiki/Cellulose_acetate_film#Decay_a... is destroying a lot of historically important documents in libraries that were laminated in acetate during the 1930s to 1950s in order to preserve them. But this kind of thing sometimes happens to architectural materials, too. https://es.wikipedia.org/wiki/Aluminosis https://es.wikipedia.org/wiki/Aluminosis is destroying a lot of buildings in Spain in the 1960s and 1970s. I've seen a similar process underway in buildings built during the same period in Montevideo, Uruguay, but I don't know if it's from the same cause. https://en.wikipedia.org/wiki/Serpentinite#Serpentinite_reactions https://en.wikipedia.org/wiki/Serpentinite#Serpentinite_reac... will destroy stone walls pretty quickly if you build them out of olivine-rich rock. Reinforced concrete, especially in chloride-rich environments, will eventually spall from oxidation of the reinforcing minerals. Some kinds of aggregate, like dolomite, although resistant to weathering themselves, also have a tendency to slowly destroy concrete. You can definitely build a wall that will last thousands of years in the absence of earthquakes, war, gray goo, or acid rain, if you make the wall out of quartz-rich or otherwise slow-weathering, low-TCE rocks like granite, cement it with lime cement instead of Portland cement, don't try to reinforce it, and don't make it too long, thin, and straight, in order to reduce thermal-cycling stresses. Most of us would never think of most of those issues when we tried to overengineer. The Roman aqueducts have some other interesting virtues, though: due to the arch, they used very little material. We could probably do better with stainless steel today, but they did pretty darn well with masonry. I don't know if you've ever tried building a masonry arch, but there are some nonobvious considerations, and a mistake can kill you.
    - Zardoz84 11y ago
      You should look to the Roman Pantheon building https://en.m.wikipedia.org/wiki/Pantheon,_Rome https://en.m.wikipedia.org/wiki/Pantheon,_Rome
      - kragen 11y ago
        Yes, the Pantheon is a good example of what I was talking about — except that it's built with Roman concrete, which is substantially more weather-resistant than modern concrete, for reasons that are still not well understood. It's probably a matter of using slightly different pozzolans, but the Roman concrete manufacturing process was lost with the fall of the Western Roman Empire. So if you were to try to build a Pantheon today, you'd have a good chance it would fall down in only a century or two. Lime cement, though, we do still know how to make, and it has the advantage of having a lower TCE, which will reduce thermal-cycling stresses on your wall when combined with other low-TCE materials like granite. Both lime cement and Portland cement can suffer pretty badly from acid rain, a problem that was only discovered in 1853 (just yesterday, in the lifespan of the aqueducts or the Pantheon), and which I think we're well on our way to solving. It might come back, though, and it's harsher on lime cement than on Portland cement. This should reinforce my point above about surprising failure modes in things that you think you've "overengineered" to last for the ages.
    - Laforet 11y ago
      Zinc and zinc alloys are also known to produce whiskers slowly (or rapidly if subjected to temperature/stress cycles) which can short circuits over time. https://en.wikipedia.org/wiki/Whisker_%28metallurgy%29 https://en.wikipedia.org/wiki/Whisker_%28metallurgy%29 This is especially a problem in RoHS compliant appliances as the common additives, i.e. lead, used to supress whisker formation in solder cannot be used.
      - kragen 11y ago
        Yes, although it's tin whiskers rather than the zinc whiskers that come from solder. It might be the same mechanism, but the mechanism isn't well understood yet. Which is kind of funny, given that we've been smelting tin since the beginning of the Bronze Age; you'd think we'd understand it by now. I thought about bringing up tin whiskers in my earlier comment, but I decided I was already going over my non-architectural surprising-failure-mode word budget. :)
  - mekael 11y ago
    I wouldn't disagree that you and I could build a wall that would be fine for a thousand years, but could either of us build a wall that could be used daily for a large part of that time? I realize the idea of using a wall is awkwardly phrased, and I pre apologize.
veddox 11y ago
We live in a time and a culture that tells us that "newer is better". But sometimes, the "ancients" weren't that stupid after all...
mooreds 11y ago
More on this: http://www.romanaqueducts.info/q&a/11stillinuse.htm http://www.romanaqueducts.info/q&a/11stillinuse.htm

This isn't specific to computer or software engineering, of course. There are still Roman aqueducts in use that were engineered thousands of years ago.

by smeyer 11y ago

This isn't specific to computer or software engineering, of course. There are still Roman aqueducts in use that were engineered thousands of years ago.

mekael 11y ago

I'm fascinated by things like the aqueducts. The skill to make them is something i can never comprehend.

grayclhn 11y ago
Overengineeing doesn't take nearly as much skill as you'd think. It would be pretty easy for any of us to design a wall that, if left alone, would last for thousands of years.
- kragen 11y ago
  You would think, but often things fail in unexpected ways. https://en.wikipedia.org/wiki/Zinc_pest https://en.wikipedia.org/wiki/Zinc_pest is destroying thousands of die-cast zinc-alloy toys from the 1930s to 1950s. Zinc alloys are pretty corrosion-resistant, so this was a surprise. https://en.wikipedia.org/wiki/Cellulose_acetate_film#Decay_and_the_.22vinegar_syndrome.22 https://en.wikipedia.org/wiki/Cellulose_acetate_film#Decay_a... is destroying a lot of historically important documents in libraries that were laminated in acetate during the 1930s to 1950s in order to preserve them. But this kind of thing sometimes happens to architectural materials, too. https://es.wikipedia.org/wiki/Aluminosis https://es.wikipedia.org/wiki/Aluminosis is destroying a lot of buildings in Spain in the 1960s and 1970s. I've seen a similar process underway in buildings built during the same period in Montevideo, Uruguay, but I don't know if it's from the same cause. https://en.wikipedia.org/wiki/Serpentinite#Serpentinite_reactions https://en.wikipedia.org/wiki/Serpentinite#Serpentinite_reac... will destroy stone walls pretty quickly if you build them out of olivine-rich rock. Reinforced concrete, especially in chloride-rich environments, will eventually spall from oxidation of the reinforcing minerals. Some kinds of aggregate, like dolomite, although resistant to weathering themselves, also have a tendency to slowly destroy concrete. You can definitely build a wall that will last thousands of years in the absence of earthquakes, war, gray goo, or acid rain, if you make the wall out of quartz-rich or otherwise slow-weathering, low-TCE rocks like granite, cement it with lime cement instead of Portland cement, don't try to reinforce it, and don't make it too long, thin, and straight, in order to reduce thermal-cycling stresses. Most of us would never think of most of those issues when we tried to overengineer. The Roman aqueducts have some other interesting virtues, though: due to the arch, they used very little material. We could probably do better with stainless steel today, but they did pretty darn well with masonry. I don't know if you've ever tried building a masonry arch, but there are some nonobvious considerations, and a mistake can kill you.
  - Zardoz84 11y ago
    You should look to the Roman Pantheon building https://en.m.wikipedia.org/wiki/Pantheon,_Rome https://en.m.wikipedia.org/wiki/Pantheon,_Rome
    - kragen 11y ago
      Yes, the Pantheon is a good example of what I was talking about — except that it's built with Roman concrete, which is substantially more weather-resistant than modern concrete, for reasons that are still not well understood. It's probably a matter of using slightly different pozzolans, but the Roman concrete manufacturing process was lost with the fall of the Western Roman Empire. So if you were to try to build a Pantheon today, you'd have a good chance it would fall down in only a century or two. Lime cement, though, we do still know how to make, and it has the advantage of having a lower TCE, which will reduce thermal-cycling stresses on your wall when combined with other low-TCE materials like granite. Both lime cement and Portland cement can suffer pretty badly from acid rain, a problem that was only discovered in 1853 (just yesterday, in the lifespan of the aqueducts or the Pantheon), and which I think we're well on our way to solving. It might come back, though, and it's harsher on lime cement than on Portland cement. This should reinforce my point above about surprising failure modes in things that you think you've "overengineered" to last for the ages.
  - Laforet 11y ago
    Zinc and zinc alloys are also known to produce whiskers slowly (or rapidly if subjected to temperature/stress cycles) which can short circuits over time. https://en.wikipedia.org/wiki/Whisker_%28metallurgy%29 https://en.wikipedia.org/wiki/Whisker_%28metallurgy%29 This is especially a problem in RoHS compliant appliances as the common additives, i.e. lead, used to supress whisker formation in solder cannot be used.
    - kragen 11y ago
      Yes, although it's tin whiskers rather than the zinc whiskers that come from solder. It might be the same mechanism, but the mechanism isn't well understood yet. Which is kind of funny, given that we've been smelting tin since the beginning of the Bronze Age; you'd think we'd understand it by now. I thought about bringing up tin whiskers in my earlier comment, but I decided I was already going over my non-architectural surprising-failure-mode word budget. :)
- mekael 11y ago
  I wouldn't disagree that you and I could build a wall that would be fine for a thousand years, but could either of us build a wall that could be used daily for a large part of that time? I realize the idea of using a wall is awkwardly phrased, and I pre apologize.

veddox 11y ago

We live in a time and a culture that tells us that "newer is better". But sometimes, the "ancients" weren't that stupid after all...

mooreds 11y ago

More on this: http://www.romanaqueducts.info/q&a/11stillinuse.htm http://www.romanaqueducts.info/q&a/11stillinuse.htm