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Comment by hooande | Hacker News Reader

This assumes that their technology would be similar to ours. They could have used biological mechanical parts, made from plant or animal material. They could have had radically different theories of mechanics or construction that better fit the state of the planet at their time.

In general the statement "They couldn't have been civilized because they aren't exactly like us" limits what we look for and how we look for it.

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The statement "they couldn't have been civilized because they aren't exactly like us" is a straw man though

The actual question the article posits is "Could an Industrial Civilization Have Predated Humankind?", and so it seems logical to take evidence of industry as a starting point to answer that question. A mere couple of hundred years of human industry has moved vast quantities of matter about, created many new types of molecule, demonstrably altered the climate and filled sediment beds with objects far more eyecatching and likely to be preserved than the dinosaur feathers and skin prints and footprints we've found fossils of. An industrial civilization need not regard combustion engines as the most useful power source, prefer wheels to gliders or think straight lines look cool, but it does need to be characterised by some sort of industry.

A hypothetical species of dinosaur that spent its life writing beautiful poetry, studiously avoiding dropping its organic tools anywhere they might be fossilised and generally being content enough with its life to not try to remake the planet for its convenience might even be more intelligent and cultured than us, but it wouldn't be an industrial civilization.

a human brain contains 100 trillion synapses each transmitting a signal of about 100 bits per second, and weighs 1.3 kg, for something like 10¹⁶ bit operations per second, 8 × 10¹² bit operations per second per gram. the cpu i'm typing this on weighs about a gram and has four cores, each of which typically manages about 1.5 64-bit operations 2.6 billion times a second, about 10¹² bit operations per second and also about 10¹² bit operations per second per gram. evidently the brain tissue is about an order of magnitude more computationally powerful per unit weight, and as it happens it also uses an additional three or four orders of magnitude less energy per unit weight. manufacturing it is also much cheaper. if we knew how to program it, we'd probably program globs of neurons rather than the very fine photolithographic microelectronics we are using today

neurons, however, fossilize very poorly indeed; after death they typically liquefy within days, losing all of the structure that could betray how they functioned

the particular shape of our industrial civilization is based on mass production in centralized facilities of durable goods that are identical to high precision (deep submicron precision in the case of this cpu). clearly this is not the only possible way to produce massive abundance; the rain forest or even the corn field does not work this way, but produces much more detail than tsmc does

much of the durability and fossilizability of our conventional technology stems from its stupidity. to remain standing, a two-story house would once be made with meter-thick walls, while modern hollow brick with plaster and reinforced concrete reduces this to perhaps ten solid centimeters between indoors and outdoors. more frugal balloon-frame designs consist entirely of metastable materials like wood and steel, materials which will lose their structure if left exposed to air and water, either suddenly in a fire or gradually over decades. but even a balloon-frame house is wasteful and inefficient compared to a five-meter-tall stand of bamboo

remaking the planet for your convenience is much cheaper if you can avoid spending resources on durability and fossilizability which don't benefit you during your lifetime

could you get there without a transitional phase of making lots of thick, solid objects out of materials that are stable on geological timescales? probably, but maybe not if your uplift path starts with fire instead of math...

That’s possible that they don’t have the same materials as us but they would have the same problems.

Take plastic or metal. Their main draw is that they do not decompose or degrade. There are a billion problems that can be solved when you have a material that does not naturally degrade or decompose.

So even if this civilization did not use plastic or metal, I find it hard to believe they didn’t come across a problem that needed a stable non-self-destructing material, which would then have been left behind for us to discover now.

It’s not feasible to build anything advanced if all your materials naturally decay.

It’s true that there are fewer decomposing organisms the farther back you go, but you have to go way way back to a point where the chance of intelligent life existing is pretty low.

Absolutely metal and plastic decompose and break down, respectively.

The latter, back into oil.

Sure, but on very long timescales. And eventually once you make enough of it, it gets lodged in all sorts of places, some less susceptible to decomposition, such as humans in bogs or mammoths in glaciers.

I just find it hard to believe there to be not a single trace of anything.

Not all metal. Buried gold retrieved from ancient graves looks very "fresh".

Also most of the noble metals would remain pristine: platinum, iridium, etc…

After ten million years even a large gold ingot would entirely be subsumed by the surrounding matter. Assuming a 10 nanometer/year erosion.

Eh, industrialization is heavily dependent on metallurgy.

What is the word industrial? Metallurgy, mass production, interchangeable parts, and the steam engine. Materials, tools, efficiency techniques, and energy.

The other aspect of industrialization is the sheer scale of it.

Honestly the only thing that comes close IMO is a lot of the cellular mechanisms. It uses materials in novel ways, efficient protein devices, and ATP energy. But I don't think it would scale to macro levels.

Maybe you could squint and look at ant/insect colonies?

Maybe, but on a planet that's full of rocks one would think they would have at least organized a FEW of the rocks into structures of sorts.

Mountains can turn into a flat landscape in a geological timespan. It's also possible we've uncovered the signs of these type of ancient structures and didn't recognize them as such, used the materials to build something during our past, or pretended we didn't recognize it in modern times because that would have slowed/stopped a construction project.

>"They couldn't have been civilized because they aren't exactly like us"

Well if you go back to the dawn of Homo Sapiens that's quite a ways back, but then you could rearrange that concept to say "they couldn't have been that uncivilized because they were exactly like us."

Oh, wait a minute . . .

If they were so advanced that they left the ordinary material world behind, then anything is possible. Otherwise, they would probably be like us in the sense that their in-use technologies would span every level from lowest to their own highest. As our tech improves, we continue to use the wheel and shaped stone and conrete, iron, steel, glass, knives, ceramics, etc. We still use things that are pulled out of the ground (like our distant ancestors) while also using the latest AI algos.

So, a very wide range of "industrial civilizations" would be expected to leave behind lots of basic natural materials in artificial forms. Their basic natural materials would be about the same as ours because they are found in nature and not very diverse (compared to high tech pharma chemicals or digital algos), so we ought to be finding lots of evidence of pre-human low(ish) tech, even if they were quite high tech.

> biological mechanical parts

What’s that?

A wooden cog, a chain made not from metal but from plant fibres, etc etc.

And you’re thinking that the machines that produces these plant based parts at industrial scale were themselves made of plant material, rather than plastics and metals?

What do you postulate were the power sources such an industry would have used?

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