I'm a geologist and have worked as such academically and professionally. Yes, there would be ample evidence to work out an industrial society jad once been present. The research and discovery would take time, but given what we have done to date there would have been time enough to find evidence of a society like ours.
Wouldn’t all of our oil & gas and mineral extraction leave huge evidence in the geologic record? Even if some aliens scooped up all traces of civilization from the surface, you’d still have all those emptied wells, water-filled wells, evidence from fracking, open pit mining, and all the rest.
If you entertain the notion that 55M years ago the PETM was caused by the Silurian civilization then geologically you have to realize that it was only 40M years ago that the Indian plate slammed into the Eurasian plate and caused the uplift of the Himalayas. Mt Everest just didn't exist at all back then. And shield glaciers have carved the continents on a 100k year cycle for at least the past 1M years which would have destroyed all of the surface mining evidence at northern latitudes. A lot changes geologically over those kinds of time periods.
Of course most of our oil reserves come from the Mesozoic age (66-252 million years ago) so either the Silurians quickly transitioned away from fossil fuels, or blew themselves up and went extinct before they could extract all of it.
There could have been a much larger amount of fossil fuels in the ground that was almost used up by the Silurians and now we believe what they left us with is all there ever was.
This makes me wonder: which methods of resource extraction lead to the complete destruction of evidence that resource existed, and which methods lead to a preservation of evidence? If you insert a deep well into a fossil water aquifer, and only use 10% of it, will it all have evaporated after 5 million years due to exposure to the elements?
Over the timescales we’re talking about, most all of the evidence would be shredded, compacted, oxidized/metamorphized then the above, filled with sediment then the above, etc.
One example of those - Intact fossils are very rare, and life has been ever present on the surface of the planet a billion+ years, near as we can tell.
That said, unless they weren’t around for long or didn’t have much success/impact, some difficult to dismiss evidence would likely to be present somewhere we ran across already - like fossils. Even if 99.99999% of all our evidence gets subducted, anyone doing as much digging 50 million years from now as we’ve done recently would have a hard time missing all of traces we’ve left.
A really weird set of isotopes and geological features
(like in Oklo, but not explainable naturally) from something like the National Test Site, or a layer of something like lead or mercury or radioisotopes in the sediment record not explainable by other means (like we’ve left), or a landfill full of plastic+stainless steel+carbon since metamorphized, or weird geological features like road fragments with no plausible natural explanation.
So unlikely, but not impossible. We are talking lengths of time 1000x (approx.) the furthest back of our own artifacts we’ve found.
But then we often have nothing for millions of generations and absurdly large amounts of biomass for species that we know well enough to know where to dig – but nothing was preserved there, and we can't dig in more than a few tiny spots. The crust's top layers are an immensely big volume and very hard to penetrate and not sure there would be a reason to dig right into an oil well that was emptied millions of years ago. Also, there is a strong aversion to sensationalist explantations in the sciences, so such scratches might even be known but attributed to some ill-understood kind of volcanic activity or earthquake scarring just because speculation towards a Silurian civilization isn't conducive to swift career progression.
Among the stuff we can use to proof the hypthesis of such a civilization (from skimming the linked paper):
- evolutionary evidence pointing at the possibility of species with large enough brains to build industrial civilizations
- sedimentary proof of artificial pollution and CO2 levels
- fossils
Any hypothesis has to be proven to be true, proofing it to be wrong is impossible and not things work. What the cambrisge paper did, was pointing towards wayw to proof the existence of an ibdustrial civilization millions of years ago. Now the work is on the people believing that theory to proof it.
Speculating without considering the basic principles behind said claim, concluding it is impossible to proof that theory wrong and finishing all that off with a the claim that such a civilization most definetly did or could have existed is just stupid. It worries me so, that this kind of shit shows up on HN more and more often.
> proofing it to be wrong is impossible and not things work.
That's pretty much entirely how science works ever since Karl Popper: You find an observation that the hypothesis cannot predict or predicts wrong. Bam, hypothesis falsified and rejected, no matter how much positive proof was uncovered until that point.
We have a different view when it comes to the hypothesis then: the hypothesis is that there was no pre-historic idustrial civilization, proof that hypothesis wrong. The paper we discuss gives hints on how to proof that non-existence hypothesis wrong, or, in my ill choosesn words, proof the existence of said civilaztion.
Or, if you like, find and show proof making the existence of such a civilaztion likely. And no, the burden of proof is not on the side diaputing the claim of such an civilization, as only the existence of something can be proven, not the absence. Hence the very exact formulation of any null-hypothesis.
Coming back to some pre-dinosaur industrial civilization (why stop at industrial so, why not an instellar one?): there is a ton of data and samples from that time periods (litterally reaching back hundreda of million of years), so everyone trying to find evidence for such a very bald claim has a lot of data to work with. Just putting out the claim and saying it must be true brcause nody can proof it wrong is not how things work, in reality that is, on the internet everything goes apparantly.
The comment presents no arguments aside from a fallacious one (argument from authority).
>but given what we have done to date there would have been time enough to find evidence of a society like ours
Geology is a relatively young science. Today's widely accepted facts were laughed at only a few decades ago. Take Wegener's plate tectonics theory: He was ridiculed for it and it only started to become mainstream accepted opinion among geologists after his death, around the 1960s. Your grandparents may still have been taught the land bride idea¹ when they were kids, which nowadays is seen as extremely ridiculous. Yet many today, who may not consciously be aware of these developments, assume that science™ has always known this and that we basically understand earth. We've barely started scratching the surface, in the literal sense.
As for hypothetical civilizations lost millions of years ago, there is no way one can rationally claim to know for certain, it depends on so many factors. The Silurian is merely an example, since this is a thought experiment. It could have been much longer ago, it's speculation. But let's assume Silurian it is, and let's say plastics would stay detectable that long (we don't know this for sure). All you have to have is a civilization that didn't invent them, or didn't widely use them. And no nuclear bombs either - hardly inconceivable. Though as an aside, the half-life of Plutonium-239 is only around 24k years! So good luck detecting that.
“Laughed at” and “ridiculed” seem to be common aspects of a dysfunctional science culture. In that, I always maintain heavy skepticism of loud, and especially media-echoed, claims scientific consensus. I say that generally.
Science that's far from politics and monetization seems generally in good shape, at least from a distance? For instance theoretic cosmology has all sorts of 'deviant' theories being widely pursued and researched in a healthy fashion. At least this correlation definitely seems to hold in reverse, where science that is closely tied to monetization or politics seems to be exceptionally intolerant, dysfunctional, and (probably consequently) also prone to absolutely abysmal replication rates.
How is monetization the problem? The biggest issues with non replicable science are all in academia which is grant funded. Corporate labs don't seem to have unusually big issues with non replicable research. Obviously, add if they couldn't replicate it they can't monetize it.
Tobacco funding research to prove smoking is healthy.
> The biggest issues with non replicable science are all in academia which is grant funded.
Yes, that was his other point, politically charged topics are bound to create bad science. So things related to poverty, intelligence, gender, race, education etc.
Medical research, especially pre-clinical, stands shoulder to shoulder with social psychology in terms of replication rates. Wiki has a brief paragraph on it on their replication crisis page [1], but this [2] page does a far better job of conveying and citing all sorts of interesting data and studies.
The pathway to profit for medicine is getting the FDA to approve your drug. This should only happen if the drug works, but the way the FDA determines that is by the data and studies you give them. Well at least in theory, there's also complete nonsense like aduhelm where the FDA even approved a drug their own medical panel concluded didn't work, leading to mass protest resignations. [3] That's probably an argument against shenanigans (why even bother?), but I still think it's relevant just to emphasize how dysfunctional our medical regulatory system has become.
Yep. To be fair the plate tectonics one is an extreme example, it's a famous paradigm shift. But it should make you think, eminent experts in the field went as far as calling it "pseudo-science". They didn't simply disagree with it on a professional level, some of the personal attacks against Wegener were quite vile.
What if it wasn't at our scale but more like late 1800s europe and limited to regions like phoenicia, mesopotamia or the mediterranean coast.
Places like alexandria have a ton of history under the city that can't be explored because people live there now but what if what people were building on top of 2-3k years ago was on top of a ruins that existed millenia before their time?
When you find roman ruins for example you would stop digging right?
I like the origin of “Silurian”, especially the caveat in the second sentence.
> We name the hypothesis after a 1970 episode of the British science fiction TV series Doctor Who where a long-buried race of intelligent reptiles ‘Silurians’ are awakened by an experimental nuclear reactor.
> We are not however suggesting that intelligent reptiles actually existed in the Silurian age, nor that experimental nuclear physics is liable to wake them from hibernation.
I'm somewhat surprised he didn't talk about evidence of space-faring ancient civilizations. If humans perish and a new intelligent species comes around in millions of years, they would be able to find stuff we've left on the moon, provided we pepper it all over its surface so as to survive any future meteor impacts.
12 people have been to the moon for about a total human surface time of about 6 days 17 hour mostly spent most of that time spent within a small radius near the six landing sites. and we haven't bothered to go back in over 51 years the number of tablet you would have to bury on the moon for a civilization as advanced as our to find one would be ridiculous you would essentially have to tile the moon in them for us to have guarantee we would have found one of them.
The Lunar Orbiter Laser Altimeter has mapped the lunar surface to, best as I can tell from a quick search, about 1m resolution. So I think a reasonably sized stele or 2001-style monolith would probably have been discoverable at our current tech level.
But we wouldn’t be able to detect human level lunar activity in a million years time.
We can barely detect human activity from 50 years ago when we know exactly where it is.
I think we are More likely to spot ancient Geostationary satellites, which will have drifted away from a perfect circle but should still be noticeable. LAGEOS aren’t in anywhere near that high an orbit but should survive 8 million years. They have a plaque on them designed by Sagan should a future civilisation find them.
But we haven’t put anything built to last on the moon - rovers and landing stages are very small and relatively fragile
A similar civilisation may have gone to the moon, but thanks to irradiation and micrometeorites over millions of years. Footprints and tyre tracks would certainly be gone, and while you could land at an Apollo landing site and detect remains of refined metal, it’s unlikely to be something you could see from orbit with our level of equipment, you’d have to get up close and personal, and we haven’t done that.
How long would it survive as a monolith on the surface before it would appear to be another boulder? How long until it is illegible due to micrometorite abrasions?
The “2001” monolith was heavily implied to have been explicitly buried. It was detected first as a magnetic anomaly, and when touched while exposed to sunlight it emit an enormous RF burst.
In other words, it was specifically protected from the elements, in a way intended to be detected only by a species at a certain minimum level of technological development.
I see people think about what evidence for what we've built might exist after millions of years but I wonder if evidence of what we've destroyed might be more lasting? Just out of curiosity I wonder if in the future we will be able to rule out "natural" causes (such as volcanic activity/meteorites/gamma ray bursts etc) and find otherwise unexplainable mass extinctions.
Read the paper. The fossil record is very incomplete, only a handful of species are known from it compared to the abundance of variations that have ever existed. We have evidence of mass extinctions far greater than that caused by humans but there were many smaller scale ones among the background noise of normal extinction.
Right.. but that's why I said "in the future". I know there's little evidence and I commented elsewhere that this paper comes to the same conclusion as the Kurzgesagt vid. What I'm suggesting is with future tech we might get a better mapping of these extinctions and the identifiable causes if known. I'm not suggesting we will find fossils that just don't exist.. but maybe getting a better holistic view of each layer around the earth.
Shouldn't atomic testing have produced a layer of light platinum group elements (predominant in fission products) that are not associated with heavy platinum group elements (rare in fission products)? Anomalies in the concentration of PGEs have been seen as indicators of meteorite impacts before:
Perhaps we should create stone tablets akin to the voyager records that we scatter all over. Ideally they give a set of precise dates and times where we plan to be “listening” — just in case we can test whether we can receive messages from the future.
The Dark Forest idea was pretty convincing to me. I'm not sure we should throw around information about our existence, not until we learn more about other space civilizations.
The critique here is that the primary discussion is about fossilization rather than geological modification. A brutalist architecture building acts kind of like a granite batholith in sedimentary rock. And yes even then eventually things will likely be recycled but for definitions of the "last couple hundred million years" the argument can be made that there will be signs that something was making changes with intent.
In a scenario where sea levels rise, and it is surrounded by sand which is then compressed into sedimentary rock which carries it around "nominally" intact I would guess it survives for quite a while. Of course there isn't anything that says we can't create some tungsten spheres as containers to hold memorabilia from the current time. Even if recycled they would not be destroyed. Of course their interiors would get hot too so you're probably want to have your information etched on thin sheets of tungsten insider the sphere.
Huh? The "last couple of hundred million years" involves all current above sea-level landmass being subducted back into the mantle - probably more than once. We're talking about the Himalayas rising up and going back into the magma of the Earth's mantle and rising up again.
I am really curious what kind of sign you envision will survive that onslaught.
perhaps another interesting question - how to deliberately leave an indicator that we did exist? i would suggest the moon landing sites, and maybe the stuff we have put in the lagrange points (don't know how stable those are over long time spans are)
Best bet I can think of would be to mass produce something that ~doesn't decompose and spread a bunch everywhere so at least one will be found.
Something like diamond plaques with writing on them, maybe just reuse what we put on Voyager but in different materials.
I bet there's a better material than diamond, not sure what though. You'd want something that lasts, but not something that can be reused. Eg don't use gold, someone will melt it down later...
Enormous piles of very skillfully worked massive stone blocks. Artifacts made of common, long-lived matter so precisely crafted that we could barely duplicate them today.
You mean like pyramids? Heh look at what few thousands of years caused to them, and its not even very challenging environment (very low humidity, mostly sand abrasion). In fact, go to mountains and actually try to look around a bit from geological perspective - they are constantly being weathered, all types of rock, by mostly rain and elements. Elements cut through stone like through butter.
Just because something doesn't visibly keep disappearing in front of your eyes doesn't mean its some ultra stable form to last for a billion years.
Also, one proper earthquake and your fine stone structure is a big pile of rubble. Now do it 100x.
From a geological perspective, several types of rock will last more than long enough. Maybe you're thinking too long-term, heh.
During the last 2.6M years - and man's been around -at least- that long - there've been a dozen or two ice-ages. Between them were interglacials, some of which lasted 2 or 3 times longer than our 10,000-year holocene. More than enough time and resources for an earlier (even wiser or saner) humanity. Or three.
Or we could mark the Earth-facing side of the Moon somehow; that would endure over geological time scales. Maybe not via massive excavations with nuclear charges (sounds like vandalism to me), but, say, hundreds of kilometers long figures/patterns made with aluminium foil sheets hung on poles, or just spread on the regolith (so - easily removable).
Stone blocks will be quarried, weathered, ground by glaciers and then subducted beneath the crust. Small artifacts disappear even faster and are harder to find.
Maybe to drive this point home from another point of view: the dinosaurs roamed the earth for tens of millions of years. We have so little evidence from that, that our ideas what they looked like have changed significantly from the portrayal in Jurassic Park.
Humans have been around for a frw hundred thousand years (if you're generous). Our current traces will be gone in a few million.
> perhaps another interesting question - how to deliberately leave an indicator that we did exist?
Replace as many plants and animals as we can with genetically engineered versions that have messages encoded in their junk DNA.
That would not be good enough to tell aliens who visit long after all life on Earth has gone extinct that we were here, but could work for future intelligent species that evolve from existing Earth life after humanity is long gone.
It's interesting to think that some peoples could have made it to the iron age. Finding random streaks of iron and rocks wouldn't be out of place in most places in the world, they'd have to transport or build some far away rock. And even then we'd probably just attribute it to the latest ice age or some other geological event.
The question is how much of the surface is still the surface, and if the old surface would be encountered by us (e.g. while digging) or is now deep down or churned into magma....but this would obviously mean that the civilization occurred prior to dinosaurs...and if there was one thing that a civilization wouldn't stand for is dinosaurs eating them all up.
There would be thousands of perfectly circular holes drilled straight through many older layers of rock, with casings, from fossil fuel extraction. They would presumably be filled with sediment, but still obviously artificial.
We have fossils from the Cambrian period ~500 million years ago that include many traces of holes from burrowing animals. We've identified animals from ~500 million leaving many different kinds of traces as well as from fossils. 500 million years from now humans will have left many remaining traces. While older fossils are rare and precious, there's no generalized entropy that just destroys all old things (until there's a supernova/mega-meteor/etc., eventually the planet will be gone with enough time). In the right conditions much can be preserved for hundreds of millions of years. Many human artifacts like gold and other inert metal tools will be around besides the many physical changes we've made across the surface of the Earth.
There is one constantly happening thing that wipes the slate clean - tectonic plates movement. You can be lucky with a spot that doesn't disappear into Earth's mantle, there are few spots like that on Earth, but its not granted.
While it is true that over deep time less and less survives due to subduction not all areas do, and human activity covers vast surfaces now leaving many artifacts and traces. You should also consider that we do have fossils from > 3 billion years ago. Certainly not everything will survive but there’s no question some human traces will persist for hundreds of millions of years.
How do we even know those holes are 500m years old? You cannot carbon date a rock (that's when the rock formed, not when the hole was made). Perhaps we're missing evidence of earlier civilizations in plain sight
It’s well worth reading about this. The ways that scientist have determined these things are complex but easily discoverable on the Internet.
Also, while I was using hundreds of millions because that was the timeframe of the original question, the reality is that we actually have fossils that are more than 3 billion years old.
There's more. At the same time oil well holes are drilled many orders of magnitude deeper making them cross thousands of strata rather than being limited to a meter or two. Most oil drilling is in areas prone to subduction but there are areas in Canada where they're drilling over surface rocks that are hundreds of millions of years old. Those won't subduct soon and are far more discoverable than an animal burrow due to size. We've got around 1 million active oil wells in N. America, fewer than animal burrows, but in areas they'll be preserved in deep time and in sufficient numbers there's a reasonable chance of discovery.
I believe things like the Hoover Dam or a skyscraper with its glass, steel, aluminum, concrete and myriad human artifacts would leave behind a significant amount of artifacts which will be detectable even after millions years.
Its a reasonable question - what human made artifacts would survive for hundreds of millions of years? Would concrete and steel buildings still be intact after hundreds of millions of years of erosion and weathering? Would objects in a 5 story deep basement be intact? Would even something we placed on the moon be visible after a 500 million years of micrometeorite impacts?
Erosion would happen, but also icebergs would wipe out anything like buildings during the next ice age. And eventually subduction would consume the existing earth’s surface into the inner molten layer, leaving behind zero trace, but that might take hundreds of millions of years.
Interesting! Thank you. So craton areas, say, near the equator where icebergs may not reach, could possibly contain remnants from indefinitely old civilizations?
Which exact artifacts do you have in mind that won't desintegrate in a few hundred million years? Pyramids won't last even one million and they're not among the most fragile products of human civilization.
You may have confused geology with archeology, they operate on completely different time scales.
Coins in the right conditions last two thousand years easily (I collect ancient coins, have some that are 2500 years old that are in excellent condition). I expect in the right conditions some would last a few hundred million years. There's plenty of other non-biodegradable, chemically inert, discoverable things like stainless steel tools, gold jewelry, and other artifacts that humans make that could easily persist for millions of years.
As soon as coins appear in a geologic stata they become the most common archaeological artifacts found from humans, and at this point we've got hundreds of billions of them spread all over the globe with many becoming lost in spots where even if they were submerged in water, they could easily still remain intact for hundreds of millions of years. Not all coins are inert, but many are, and many really are going to stick around millions of years. While volcanic heat and pressure can mangle inert metals, not many other natural processes will. There's no magical entropy that would cause inert artifacts in geologically stable areas that some coins would wind up in to just lose their form magically. In our world today there's a lot of stainless steel, gold, and other inert artifacts that are going to persist for hundreds of millions of years. It's not like there's volcanoes everywhere, nor do tectonic plates subsume everything - we've got Cambrian fossils after all...
Depends on the sort of water, I guess. Salty and oxygen-rich wouldn't be so good. I'll just leave the https://en.wikipedia.org/wiki/Antikythera_mechanism here for you to think about. That had ca. 2100 years +/-ca. 100 years of underwater seawater exposure, and look what it did to it.
What would only 10000 years more of that have done to it?
That's bronze. I'd assume any brass/bronze/copper to corrode away, that's what it does naturally. Now consider gold, stainless steel, and the many other inert materials humans work with. I assume 10,000 year old gold artifacts would look the same as the 5000 year old artifacts we know of which are very well preserved, and other similar materials would fare similarly.
A million is a mind bogglingly large number, especially in years. I honestly can not say eitherway if anything survives. Coins might end up as a lump of rock with slightly higher metal content than surroundngs.
It is a very long time, but we still do have a lot of fossils, and with many human artifacts they won't fossilize so much as just sit there in their strata - we make artifacts that don't even need to fossilize since they are already stable, chemically inert, and resistant to biodegrading or corrosion, and if they do corrode, then in the right conditions those would be a kind of fossil. Ancient life made left lot of traces and humans are currently leaving as many traces as any other species has ever left, and we're leaving artifacts and other traces spread all across the globe, even in the oceans. We have fossils from >3 billion years ago. Not everything subducts. There's existent areas of long term geology stability and those areas are as littered with human traces, artifacts, and other remains as anywhere else. I honestly can't imagine all traces of humanity being undiscoverable considering in 100 million years, in 400 million subduction and time will have erased a lot, but I'm pretty confident there would be quite a few discoverable traces if some future life form were to apply modern archaeological methods then, esp. given that the scale and scope of changes humans are making is massive and global. At the very least future paleontologists would see the effects of humans on their habitat in the fossil record of the ongoing mass extinction, but I expect much more would be discoverable than that.
There’s still a lot of room to hide in that “almost”. Continental shields in Canada and Australia haven’t been recycled into the deep Earth and we can still find geological features there that are billions of years old.
We have fossils that are > 3 billion years old. While subduction does steadily erase the past, not everything subducts. See:
https://en.wikipedia.org/wiki/Craton
Hmmm, assuming there were an extra retro reflector on the moon, have we pointed a laser at enough of the moon to find it? At what rate would it acquire dust without wind?
i think you would be more likely to detect a prior advanced human civilization from 100k+ years ago rather than some other species from 100m+. and we don't have any of those either.
a planetary apex species capable of industry would have funerary rituals to prevent anything from learning a taste for their bodies. their dead would be well protected from harm if they weren't already somehow destroyed, and this would probably prevent any form of fossilization to be found later.
even assuming you can't find their biological remains, you might expect to find metals they had used, perhaps within a similar context that we find fossilized remains already. an unnatural combination of metals under some soil.
i've seen one conspiracy-like youtube video of this[1]. i haven't seen any other sources and i doubt this is real. even if it sounds cool conceptually, the video gets a little over the top in craziness, especially for something that has basically zero sources but would be widely known if it were true.
based on my limited understanding of these chemicals, things like gold, platinum, titanium, would likely be left over in a relatively non-degraded state.
and if legitimate traces could be contemplated, for any tests based on organic elements i would expect a kind of signal compression or expansion to happen in the soil over time due to pressure, diffusion, and potentially something like moisture.
>a planetary apex species capable of industry would have funerary rituals to prevent anything from learning a taste for their bodies. their dead would be well protected from harm if they weren't already somehow destroyed, and this would probably prevent any form of fossilization to be found later.
That seems to be making a lot of assumptions. Why couldn't tossing bodies into a tar pit be a funerary rite?
a tar pit as in the ones formed from petroleum, as in when crude oil rises to the earth's surface? as in the crude oil made from all the extinct dinosaurs from hundreds of millions of years ago?
its a nice idea, but its technically putting the cart before the horse as those pits wouldn't have been around due to them being formed from decaying organic matter from that time. if you're trying to say those could have been locations where those rituals might have taken place, i suppose its fair enough to ask that, to test it you could check the locations and crude grade of all currently known oil locations, and if you manage to find similar grades on land as you find in the middle of the sea, especially in locations that were never land to begin with or weren't land during those time periods, then that would disprove the idea because they wouldn't have made tar pits in the ocean. there probably other ways to test this idea but this is what i have off the top of my head.
You’re picking out what was obviously an example of a burial rite that involves permanently destroying remains.
And I agree, it’s quite anthropomorphic to assume another intelligent species would place as much emotional value on graves as humans do. There’s really no reason for it other than some historical/superstitious customs.
If you think about how strange and hard to comprehend even fungi or octopuses are, I don’t think we can make any assumptions about the culture of a non-human intelligence. Going as far as claiming they would bodies their deceased is borderline ridiculous.
>as in the crude oil made from all the extinct dinosaurs from hundreds of millions of years ago?
Oil is not primarily made of dinosaurs but rather of plankton and algae.
>its a nice idea, but its technically putting the cart before the horse as those pits wouldn't have been around due to them being formed from decaying organic matter from that time.
You're talking about 100 million years ago as if that's a tremendously long gap but glossing over a span of about 400 million years as if it were a single instant. At any rate a tar pit was just an example of an environment that is conducive to fossil formation.
It's interesting to me to compare this with the curse of Tutankhamen's tomb -- it didn't stop us. I doubt these warnings alone will stop future us from opening anything. People will probably say the radiation is there to stop people from stealing the treasure and send something 'disposable' in to open the containers.
I would think that a civilization like ours wouldn’t have left the amount of fossil fuels that we still find. We certainly aren’t going to leave that much for future civilizations.
This was mentioned in The Mote in God's Eye. Later civilizations had to go straight to renewables or nuclear because no accessible fossil fuels were left.
Fossil fuels are a renewable resource on the geological time frame. They're not use once and gone forever. Most of the oil we know of today was formed in the Mesozoic and later. So after the Silurian.
In fact, suspiciously, only a small percentage of what exists today is assumed to have been formed in the Paleozoic. If anything the notion that they'd have used up the fossil fuel only supports the idea that such a civilization may have existed, if anything.
But of course one can also point to the simple fact that we're already transitioning to renewables and we're far from being short. We just do it because it's better. So why couldn't a past civilization have done the same?
The jump to either is fairly trivial because hydropower is so abundant. 18% of the worlds current electricity is supplied by hydroelectric power. Considering we developed nuclear energy using 1940’s industrial capacity hydro could easily bridge the gap.
Similarly while trains needed fossil fuels ships didn’t and allowed for very efficient transportation of goods on the ocean and inland through areas with sufficient rainfall. The major historic use of coal was for heating, but much of the earth never gets that cold.
Almost all of our current hydropower is based on damns made of concrete. Creating the cement for that is very energy intensive. Also turbines and generators are made of metals which require a lot of energy to melt.
Probably you can bootstrap a waterpower based industry somehow without fossil fuels but it is not trivial.
The other thing is that each incremental step in such a process has to provide some benefit to the participants. For example you are not going to have generators without readily available good quality copper wire, but bootstrapping a copper refining and wire making industry without fossil fuels is very hard. Those people need to see a reason for doing it in a world where there is no electricity yet therefore there is very little need for said copper wires.
Historically the Industrial Revolution was mostly bootstrapped by hydro / biofuel power. Useful combustion engines were only invented fairly late in the process. You don’t need to start with massive dams, you need to bootstrap industry to get to that point. Even 0.1% of the worlds current electricity generation is a massive amount of energy.
There’s this idea that the Industrial Revolution ran on coal but Coal was an inferior fuel for steel production until ~1827 or so.
Eventually steam locomotives beat horse / manpower drawn canal boats, but it a close contest until surprisingly recently. Hell the last commercial cargo sailing ship was in use until the 1960’s long after nuclear power became a thing.
> Almost all of our current hydropower is based on damns made of concrete. Creating the cement for that is very energy intensive.
Is that really harder than building hundreds of kilometers of aqueducts? Humans have known how to engineer water flows for thousands of years, if we valued power we would build those dams. That power would be more expensive so it would slow down the industrial revolution but it would still happen.
Also you don't need continuous power for an industrial revolution, that is convenient but factories are still revolutionary even if they just run half the year.
The issue isn't electricity, it's energy. How do you run your first ironworks without coal? You can't really exploit hydro for electricity without industrialization, and you can't really have an industrial revolution without coal.
England ran out of Land not forests. They set aside large tracts of land for growing wood starting in the Middle Ages because having wood was useful both as a construction material and for burning.
Critically, you can move wood long distances so running out locally isn’t an major issue as long as you don’t run out globally.
Early Ironworks couldn’t use coal due to suffer issues, the US didn’t swap until 1827 long after the Industrial Revolution kicked off. Also, we’ve used a relatively small fraction of the worlds coal supply, so there’s little reason to assume a prior civilization would have used it up either.
A large fraction of the early/mid Industrial Revolution was powered by hydro/wood. Abundant rainfall is why so much industry ended up in the north eastern US and England. Efficient motors was more a result of a scientific and industrial innovation rather than the cause of such.
So suggesting Ironworks as a major obstacle doesn’t really stand up.
That’s not true. We use syngas (about 50% H, 50% CO) in all the iron ore reduction plants built in the Us in the last few decades, and they can run almost entirely on hydrogen.
Additionally, coal wasn’t even used for making steel in the US basically at all until 1827 (charcoal has fewer impurities like the sulfur found in a lot of early coke). The US primarily used charcoal from wood even for iron production until well into the mid 1800s (and by 1884, charcoal was still used for 10% of iron and steel production in the US, and charcoal was still used in some niche areas even into the 1940s). And steam locomotives in the US were also often powered by wood in the 1800s.
My understanding (which could certainly be incorrect) is that most fossil fuels formed between the evolution of trees and fungi that could breakdown lignin and so most fossil fuel deposits were ancient even to the dinosaurs. I doubt that significant stores would form between now and the deadline for life on earth in a few hundred million years.
Yeah, (un)fortunately simple math is all you need to see the carbon cycle could not possibly have worked that way. There isn’t enough carbon produced under the proposed scenarios to support hundreds of years of tree growth, let alone millions. There was probably other stuff that broke down lignin.
Or maybe fossil fuels used to have springs all over the place. In medieval times there actually used to be oils streaming to surface and used in mundane lamps.
Machine it into a gauge block for some obvious technological precision. Maybe carve it.
I read once that stamping serial numbers into steel changes something at a molecular level in the steel, so that filing them away is not enough to remove the number entirely. Maybe we can do that to tungsten.
I remember this being posted here a few months ago. There's the question of evidence but also simply the question of prerequisites for technological civilization.
People have mentioned fossil fuel depletion. These do renew on geological timescales, but there's a minimum bound of when they could have started to accumulate. The reason we don't have fossil fuels going back further than the Palezoic isn't because a far-past civilization may have depleted earlier stores, but because the types of organisms that eventually create fossil fuels didn't exist at a large enough scale until the Carboniferous period, which occurred in the late Paleozoic. There are other possible sources of energy, but none as easily accessible as igniting a high-energy combustible material.
There's the general evolution of bodily morphology necessary for advanced tool creation. Although I am sometimes struck during all the nature documentaries I watch of animals stuck in rough situations where greater intelligence might have helped, I am far more often struck by animals that would have been helped by grasping hands. Among sea-dwellers, you've got the tentacles of certain cephalapods for combining manual dexterity with high-intelligence and that's pretty much it. Even extremely intelligent whales are quite limited in what they can do with tools because all of their limbs are taken by locomotive purposes, whereas cephalapods often move via jet streams.
On land, this requires bipedalism, so when did this first start to show up? There are no bipedal reptiles. Bipedalism in mammals is quite late arriving just because mammals are quite late arriving. It's not entirely limited to apes. Otters can do quite a bit with their hands, raccoons to some extent.
Birds unfortunately ended up needing their wings to fly. Earlier dinosaurs did have grasping hands and likely at least a few of them had pretty decent manual dexterity, but these didn't show up until the Jurassic or so.
Then there is intelligence, and not only intelligence, but the need to learn. Species that develop cultures and highly-adaptable learned behaviors tend to have both longer gestation periods and longer times to reach sexual maturity and adulthood. This makes them more dependent on parental nurture. These are r-selected species, which again, I don't believe includes any known reptiles. It seems to have become a common strategy with mammals specifically because mammals developed the ability to secrete milk, and in birds via gaining the ability to store food they could regurgitate from their stomachs. This allows young to not have to fend for themselves and they can spend years learning all of the complex behaviors required to do something like create a civilization. Neither of those traits showed up until after the K-Pg extinction.
There's the rather obvious constraint that you need to be a highly social species in the first place. Intelligent or not, you can only build a civilization through the coordinated actions of many across large divides of time and space. Social behaviors and division of labor show up in colonial insects and you could even argue they have something akin to civilization, but their small size seems to preclude the level of intelligence necessary for what we would recognize as an advanced technological civilization. Large-scale social behaviors in larger animals has tended to show up for one of two reasons, either because traveling in herds offers protection from predators, or because hunting in packs allows for all to thrive even if only a subset of adults at any one time are capable of acquiring food while other needs to focus on learning, play, or child-rearing. The group intelligence and behavioral sophistication required for herds is not as great as for hunters, so we would probably expect predators to be the ones who might develop technology and civilization. This is again not something we see in reptiles. It shows up in birds and mammals, but also not until after the K-Pg extinction. Some types of dinosaurs very likely hunted in packs and had social communities with division of labor.
Once you have those things, you still need a means of communicating and recording highly technical and specialized information. In humans, this required specific mutations in the linguistic center of the brain and in our mouths and throats to produce language, and these only happened in the last million years. That is, of course, not the only way to do it. Certain whales might have sufficiently sophisticated vocalizations that, if they had the means to invent writing, it might be enough. Some of the chemical ways in which certain types of insects communicate could potentially be far more sophisticated than we could imagine, but again, they're insects and limited in what they can do with extremely small brains. Birds also have extremely sophisticated vocalization capabilities, but can't write because of lack of manual dexterity and they don't show up until after the K-Pg extinction. Reptiles don't seem to have particularly sophisticated communications capabilities as far as we can tell.
This again leaves open dinosaur capabilities we may not be aware of.
All in all, it just strikes me that all of the prerequisites I can think of that have to be present on the biological level show up the earliest we know for sure sometimes in the late Cenozoic after the K-Pg extinction, and well after really, given the need to recover. The very earliest they might have occurred in earlier types of land animals that show the necessary morphological and behavioral traits is the Jurassic. The idea that organisms like this may have actually existed in the Silurian just seems mind-bogglingly unlikely. Forget about the visible effects they may or may not have had on the surface of the Earth or potentially nearby non-Earth bodies. How and why did their entire evolutionary family tree disappear and leave no descendents?
Steel corrodes away on much shorter time scales. Concrete also eventually breaks down due to repeated thermal cycling and weathering. Even if some steel or concrete survives it might be buried and difficult to find.
Dinosaur bones and trilobites don't last very long. What we find are fossils. Steel and concrete don't fossilize.
What if they progressed beyond that? And were mindful of pre-that clean up? In theory it feels that the more advanced they were the less likely they were to leave a trace we might find.
> The dating of ice sheets has proved to be a key element in providing dates for palaeoclimatic records. According to Richard Alley, "In many ways, ice cores are the 'rosetta stones' that allow development of a global network of accurately dated paleoclimatic records using the best ages determined anywhere on the planet".[43]
If a civilization develops stone working, metalworking, leaded gasoline, nuclear power, etc , that's all probably recorded in ice cores (that are apparently 5 million years old in bubbles).
What would be a more cost effective way to identify signs of prior civilization?
Read the emissions off in black holes that old, (or rather, black hole accretion disks, which are apparently modified Lorentzian attractors with superfluidity and Hawking radiation)
Fly there and perform multiple geologically and geographically covering miles-deep sediment sample studies,
