Seemingly everyone is talking about artifacts and lack thereof.
Maybe we should be looking for something else. Some different kinds of signs.
If -we- wanted something to outlast us, what would we build?
What can preserve information across literally millions, even billions for years?
Life.
The genomes, the bird songs, the designs some fish draw in the sea floor [0], that gland in octopuses that basically cause them to self-destruct within a short lifespan, but removing which allows them to continue living just fine?
Maybe even the growth rings of trees.
Could there be any clues encoded in those patterns? Is there no hint of genetic modification (I hesitate to say "intelligent design" because of its loaded implications related to religion) similar to what we ourselves are doing now?*
* (and have been doing for thousands of years, via selective breeding etc.)
One clue to there not being a civilization like ours in the past, is all the oil that we found in the earth. Such a convenient energy resource would have likely been used up before we arrived, had there been an industrial civilization before.
If a future intelligent species would dig around a hundred million years from now, they'd see traces of us in the form of a radioactive sediment layer.
The paper discusses the longevity of radioactive isotopes over large time scales - basically only a few isotopes have half-lives long enough to last for tens of millions of years, and those can be created naturally as well as artificially.
On the point about oil, the paper points out that oil deposits have been created cyclically over large time scales:
"At least since the Carboniferous (300–350 Ma), there has been sufficient fossil carbon to fuel an industrial civilization comparable with our own"
There were three anoxic events, where the ocean was completely depleted of oxygen, in the Cretaceous period 132, 120 and 93 million years ago.
"these [carbon] releases often triggered episodes of ocean anoxia (via increased nutrient supply) causing a massive burial of organic matter, which eventually became source strata for further fossil fuels.
Thus, the prior industrial activity would have actually given rise to the potential for future industry via their own demise. Large-scale anoxia, in effect, might provide a self-limiting but self-perpetuating feedback of industry on the planet."
Although, as the paper notes:
"Alternatively, it may be just be a part of a long-term episodic natural carbon cycle feedback on tectonically active planets."
> Such a convenient energy resource would have likely been used up before we arrived, had there been an industrial civilization before.
Isn't the earth crust constantly moving, so new petroleum reservoirs are constantly formed and other destroyed as dispersed liquid hydrocarbons move and migrate in reservoirs?
So even if a civilization depleted its reserves, then new reservoirs would be available once the crust has moved enough?
Well the carbon in the atmosphere might build up to a point that it cooks most life on earth. So probably still wise to leave it in the ground as much as possible
Not sure why you're getting downvoted. It's definitely plausible that a prehistoric civilization would have left genetic traces of meddling with other species. Whether they'd have done it deliberately or not is more of a philosophical question.
Regardless, it's another interesting question: if another civilization bred and domesticated, and possible modified, other species 200 million years ago, what genetic traces would be left in the genome of current life?
200 million years is a fair old while in terms of genetic drift, however if you were building DRM or copyright information into your engineered forms, you'd likely want to do it in such a fashion that the form would be nonviable without that set of codons.
So you'd look for things like sudden changes to respiratory complexes that seem to require a large leap, or essential amino acid codings, and try to correlate those changes via genetic clocks with the kind of thermal events described in the article. One thing that came into existence around the PETM was mammals, with all of their novel adaptations.
Still, it could be (is more likely to be) correlative, not causative - or causative in a different way - a changed environment could exert extreme pressure on forms, causing some novel mutations to take hold.
There's another place to store information which isn't in the genes themselves but in the mapping of codons to amino acids. This location would be invariant across generations.
This paper on "biological SETI" made some noise when it came out and then disappeared, literally gone from arxiv, perhaps because the crackpot smell is too strong? I am curious if it merited either debunking or further study but didn't see much of either. If there is a signal there, it seems more plausible that prior inhabitants put it there than ET.
I suspect any evidence short of multiple artifacts from multiple locations would be circumstantial at best, regardless if the traces are in the planet's geological record or in the genetic code of an ancestor of whatever the supposed ancient ones ate for dinner.
On the other hand, multiple correlating indicators could give a pointer about where to look. Alas, it's likely such a place either deep underneath the ocean floor or that it's buried under kilometres of rock.
> that gland in octopuses that basically cause them to self-destruct within a short lifespan, but removing which allows them to continue living just fine
Wait what? has this been tried? Can we make long living octopodes by just doing a small operation?
> Octopus reproductive organs mature due to the hormonal influence of the optic gland but result in the inactivation of their digestive glands, typically causing the octopus to die from starvation. Experimental removal of both optic glands after spawning was found to result in the cessation of broodiness, the resumption of feeding, increased growth, and greatly extended lifespans. [0][1]
what we've learned until now is that, if such an information processing device would have existed then any sufficiently advanced civilization would have been using it to mine crypto currency.
If 'Dinomen' existed, we may see it in the other dinos or plants via domestication. If they were carnivores, we may see dinos bred to be fatter or larger. If they were herbivores, then we'd see certain plants that were bred for food, and maybe dinos bred for labor or as pets. One of the issues with domestication is controlling the breeding/birthing cycles of animals. Chickens and pigeons tend to be easier to do this with because they are dinosaurs and lay eggs.
We see this in our own mammalian species like cows. Their bone structure is (slightly) different from wild cattle and certain breeds have massive horns because us humans just like it. Dogs too, we've made a lot of breeds of them that all look very different. I'd imagine that a lot of the world should be covered in cow and dog bones of a wide variety of shapes and sizes.
Come to think of it, the ceratopsids (like triceratops) have a large variety of head crests, there were tons of them about, and they were pretty fat and muscular. Hmmm ...
We might be able to detect genetic engineering quite simply...
By comparing genomes, you can construct a philogenetic tree of known animsls, and thier hypothetical ancestors the instances where a mutation popped into being making a species and it's defendants distinct.
You can slot genomes from near extinct species and amber trapped insects into this tree and confirm where they sat.
So genetic engineering would look like - fish genes suddenly appearing in the dog family tree or butterfly genes turning up in a plant.
This would be pretty detectable with just a computer and open data. Has someone done it?
Keep refining/miniaturizing the technology. from mainframes, PCs, tablets, mobile watches to tiny chip in brain. In energy from coal, oil, electric, solar to zero-power. Eventually the grossness will disappear to a great extent. leaving little to know artifacts. The remaining artifacts including the dwelling structures get recycled into their raw sources given sufficient time; especially if remain under water for good amount of time. Continents may fall into ocean destroying the evidence more quickly.
This is only when you are expecting a civilization as current one. How about those who weren't dependent on technology ever - they may have chosen a route to discover about the nature, the universe and themselves drastically different from that of ours and hence we, enamored by a false sense of superiority, fail to even contemplate of such possibility let alone any chance of discovering an evidence of their existence.
I have a different idea. There are numerous historical accounts of basic resources available directly on the surface. These were cleaned up in preindustrial times when we had to start to dig for them. We have already removed almost everything that was in easy reach and now the resources we are digging up are either difficult to reach or require a lot of technology to concentrate and clean up. I am convinced there were no previous industrial civilizations because we would not see so many resources available in so clean form and so close to surface.
The problem is to insert something into the genetic code that survives evolutionary pressures over hundreds of millions of years. There would of course be great irony in this point; a civilization knows how to modify an animal in a way that is more adaptable for millions of years, yet it that civilization itself went extinct.
I think a lot of us assume civilization to mean that the sapients must at least be as technologically advanced as us right now. But there could have been simple hunter gatherer societies which used materials like wood and other organic stuff for their constructions.
I think assuming that all civilizations must live in a concrete jungle like us is as likely to be wrong as to assume that all aliens must look like us, or that all life in the universe must only exist in a temperature range of 0-60'C
I certainly never had that opinion. I would consider for example the people of ancient Greece to be an advanced civilization, despite the relative lack of what we consider to be modern technology. And you can go back much further than ancient Greece for that matter.
There is a general misconception that advanced modern technology equates to an advanced civilisation. Looking back to ancient Greece, Mesopotamia or Egypt there were a lot of interesting ideas implemented in those societies that we haven't even thought of today. Ancient Greece had a very interesting healthcare system for example which was passed down to ancient Rome in some form. A lot of countries today have advanced weaponry, rockets, digital computing but haven't managed to implement a solid healthcare or education system.
It's true. We could define civilization as being consciously aware of the state of Nirvana. It's possible that early pre-human civilians all transcended long before discovering how to weave baskets or husband livestock.
If your species only needs to spend half a day foraging for food and the other half lounging under a tree contemplating the nature of existence, why bother with the grind of technology when you could jump straight to the endgame?
Civilisation is not a state of mind. That doesn't make any sense, because it is completely at odds with how the word is used in practice, e.g. "Aztec civilisation", "Western civilisation", "Modern civilisation". The actual definition of civilisation is about structured culture and communities: https://en.wiktionary.org/wiki/civilization
The wiktionary definition of "civilized" [0] is "Having a highly developed society or culture" -- developed into what, late Victorian era upper-class British men, like the people who wrote the OED the definition was cribbed from? The human species, especially those of highly developed society and culture, have a long record of exterminating others of their kind on the grounds that the others are "uncivilized".
Civilization is purely a state of mind. A species that achieved enlighnment before inventing the wheel or harnessing fire can be no less "civilized" than one that will engage in intraspecies mass murder for the right to enslave other members of their own species. I would argue they are more civilized, in fact.
Civilization means complex urbanized society. Doesn't imply technology like the present - for example we talk about the Sumerian civilization. It is really a question of how organized the society is.
I mean, the perfect seams of the joints in various Peruvian ruins, the melted rock formations, the unexplained techniques for constructing massive stone structures .. I think there is definitely a case to be made for previous, advanced civilisations, which we haven't quite yet understood properly.
But then again I could just be a victim of the Gaia spam and Grahama Hancock interviews on JRE ..
Reminds me of a story I stumbled across a long time ago (at least as measured by internet time) about a guy in Michigan that figured out a method to build Stonehenge with a small crew and simple tools:
Yeah, sure, we could build Stonehenge today, but Stonehenge is not really representative of the monolithic cultural artefacts we couldn't easily build today, and Stonehenge, while popular in the Anglosphere, is not nearly as fascinating from the monolithic perspective as Baalbek and Sacsayhuamán and Gobekli Tepe ..
These all have things we need to look into, before we make big leaping conclusions about how primitive other cultures were and how things proceeded to the superlatives of modernity.
I'm prepared to learn that the rock cultures used hand tools and it was all just a lot of back breaking labor, but I also would not be surprised to learn that a laser-cutting device was discovered in a temple somewhere, and which 'explains everything' without any hand waving alien haircuts - albeit opening too many doors.
Pretty simple. First you pick two rocks that have nearly the right shape (its obvious they did that, because each joint is clearly custom). You put some dust on one surface. Take the mating surface, and rub it a bit on that dust. That will reveal the high spots. Take a smaller rock and bang on the high spots to grind them down a bit. Repeat the process until no more high spots.
It's not dissimilar to how telescope mirrors are ground to perfection, and how to make a perfectly flat steel surface.
Doesn't explain the entire lack of tool marks, though. Or the lack of embedded shells.
I am curious about the perfectly flat, right-angled interiors of the 50+-ton (always empty!) basalt boxes in Egyptian mausoleums. We have a plausible story about cutting the outsides using copper saw blades with gems embedded in the edge, but no similar one for the insides, particularly the inside corners.
We also need to understand why the tech for working the biggest rocks was lost before the Inka took up building. The late work always uses much smaller rocks, and is relatively crude.
> Doesn't explain the entire lack of tool marks, though.
Because they didn't use tools. I've watched telescope mirrors ground to incredible precision by hand, no tools.
> Or the lack of embedded shells.
Use rocks without embedded shells.
> inside corners
Use drills, clean up with files or blocking. Remember the Pharaohs had essentially infinite resources to do that for one box. He would have used the best masons, paid them well, and gave them the time they needed.
> why the tech for working the biggest rocks was lost
We can't know why, but the most plausible explanation is one that accounts for lost technology everywhere. People didn't have writing or didn't bother to write it down or lost the books.
>> Doesn't explain the entire lack of tool marks, though.
> Because they didn't use tools. I've watched telescope mirrors ground to incredible precision by hand, no tools.
Good one. That doesn't work on non-convex polygonal shapes. Notably, the faces are not just identically curved, as one would get by interfering faces. They are both flat.
>> Or the lack of embedded shells.
> Use rocks without embedded shells.
The rock faces in the quarries have embedded shells. Only the cut faces of rocks from those quarries lack them.
>> inside corners
> Use drills, clean up with files or blocking. Remember the Pharaohs had essentially infinite resources to do that for one box. He would have used the best masons, paid them well, and gave them the time they needed.
Infinite labor doesn't help in a box. Only one or two masons would fit. We know what their rock drills were like; they had a minimum radius measured in inches. And, again, no tool marks.
You don't get to define out the unknown by inventing excuses to ignore it; that is the same as inventing aliens. It takes actual work.
Yeah, that's a bit glib. A lot of the joints and seams technology in Peruvian ruins is unexplainable - even with modern industrial processes, we would be very hard pressed to replicate the results of some of these structures. Like it'd be very, very hard to do it as well as the ancients did, even with our crazy construction technology...
1. Lots of people with lots of time on their hands did something that we'd be currently hard pressed to do but no one has really tried yet.
OR
2. Two aliens land on Earth and one of them says "Hey, how do we help out these poor savages to advance their civilization? I know, we'll teach them to build really cool walls from stone!"
...I know which one I'll pick. The wiki article doesn't offer any suspicions of extraterrestrial origin. In fact, a contemporary account suggests it's just hard work:
"to save themselves the expense, effort and delay with which the Indians worked the stone, they pulled down all the smooth masonry in the walls. There is indeed not a house in the city that has not been made of this stone, or at least the houses built by the Spaniards."
Or 3, some ancient people had better construction technology than we give them credit for. No need to bring up aliens every time someone questions orthodoxy.
Yes, there are many theories that can be entertained. My favourite is the mythos that, over a hundred thousand years, perhaps humans did evolve to the point they had technology to leave the planet, tidying up after themselves as they did, and its just us stragglers left behind that have been slowly devolving the tools they also left behind .. 'what if' doesn't have to be disregarded, just because its preposterous.
I mean, I never once mentioned two aliens in a UFO, but hey .. sure, why not.
I think people tend to overestimate progress. Skyscrapers happened a hundred years ago with advent of elevators. I've visited some Roman cites, they are massive. They had five storey residential buildings - just like these days.
Yeah, no. Its basaltic and granite blocks, literally cut with micro-mm precision, and glued together in a fashion that prevents seam gaps. These seams, in some cases, are thousands of years old ..
And then, there are the fused-rock glasses found on some monuments which defy explanation. Lightning? Perhaps, but then there's that corona eruption theory ..
Someone was melting rocks. Maybe with microwave resolutions.
Last time I checked it, it was concrete. Forms for blocks are made from animal skins. Cement was made in kiln. At least one kiln has pretty modern look.
Look, there are all sorts of schools of thought on how these things were built, but none of them were conclusive. I'm not saying it was rock-melting alien technology, but it was clearly some form of advanced technology we are unable to duplicate or conceive was available to the builders.
Here's where to go to get on the Graham Hancock/Randall Carlson train, in case you haven't seen it:
So, they made a unique, precision rock mold, exactly one for each unique, poured-concrete megalith, and then... turned the mold into more concrete, and poured that into another unique, laboriously constructed rock mold? Color me not satisfied with this picture.
Mold is made from animal skin (waterproof) and wood, then block is cast in place. Skin degraded with time, so nothing left between blocks. It's easy to notice bumps on blocks where animal legs were.
The jury is still out. A lot of these studies were re-assessed and found to be quite faulty - i.e. you cannot bang two rocks together and get a perfectly flat surface with <0.005mm deviation in flatness.
Also, there is a lot of unexplained melted rock all over Peru and Ecuador and so on. Somebody in the ancient world either had a light sabre, or .. it was aliens.
> I mean, the perfect seams of the joints in various Peruvian ruins
Er... the peruvians was an advanced civilization. Certainly advanced enough to fit stones snugly. That we don't know the exact techniques used for various ancient buildings does not mean they couldn't have built it.
In any case saying "maybe someone else did it" explains absolutely nothing. You just have a new hypothesis with zero evidence.
Ha, I was thinking, a victim of the ancient aliens series on TV. We do have a lot to think about in the past and it seems to be filtered through a very narrow modern view.
There are countless animal and plant fossils from as far back as 100s of millions of years ago. Wouldn't we have found at least a few fossils of constructed objects?
Not much, since the ocean floor tends to be quite young on geological terms. For example, the oldest parts of the floor of the northern Atlantic ocean only started to form after Laurasia broke apart 50 million years ago, and the floor of the Pacific ocean is regularly recycled in the subduction zones of the pacific ring of fire.
Right, but organisms are small, get eaten, rot etc. Civilizations change their environment, build cities, manufacture tools with stronger materials. Advanced civilizations even more so.
still today, most of our civilization lives on the coast. The coast lines and ocean levels have changed significantly over the last 100million years. whole regions, such as where England used to be connected to mainland Europe, were just submerged.
Likewise Sundaland, whose mountaintops are now Indonesia; and Sahul, between Australia and New Guinea. Australians have oral records of the upheaval that came from that flooding.
Earth has an interesting property, where it’s got just enough gravity to hold water and air in just the right amounts. And just far enough away from the sun to provide heat and cold. And that special magnetosphere to protect delicate life from being ionized by cosmic rays.
You’ve gotta wonder if lava and plate tectonics has melted away all traces of any previous civilizations. Like, the entire crust would have to become an inferno.
Maybe when the moon formed, from another planetary body colliding with the earth, that this cosmic event destroyed all previous civilizations on Earth, and made the planet inhospitable for a million years.
And maybe if that civilization became space faring, if they left technological artifacts elsewhere in the solar system. Like on Mars. Or in the asteroid belts.
Or perhaps, they were able to see the incoming collision, that they jettisoned from the solar system, and went to another star system in search of a new planet to call home.
The question being asked is not "sensationalist". It is a perfectly legitimate question of epistemology: can we know? If there ever was such a trans-ancient civilization, would evidence still be identifiable? Or is deep time as, and perhaps even more, unknowable as deep (relativistic) space?
Long before Doctor Who geologists have referred to an era in Earth's history as the Silurian. This is because it was originally identified from sedimentary rock layers found in south Wales in an area where the Romans had encountered a fierce tribe of natives named the Silures. One thing led to another and British Victorian scholars being what they were, the rocks were named after something a Latin master taught rather than anything locally relevant, like the Welsh.
Incidentally, the Silures lived in the part of Wales where the city of Cardiff is located. There is a known active rift in the space-time continuum under the city of Cardiff [0]. This could also explain much.
"We name the hypothesis after a 1970 episode of the British science fiction TV series Doctor Who" - The Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record?
https://arxiv.org/abs/1804.03748
I expected Silurian come from silicon but I was wrong. Once heard the idea that there might have been silicon based life on earth and all the sand we have is from that period - much like oil is dead carbon based life. Scientifically there is not much to it, I think, but it would make a good basis for a SciFi story nevertheless.
"The Light of Other Days" is by novel written by Stephen Baxter, based on a synopsis by Arthur C. Clarke, that deals with this issue as a "surprise" near the end of the novel. Basically, the world is in turmoil for a series of reasons worse than what we have going on now, and then it is discovered we're the 2nd advanced civilization to evolve on Earth, with details of them and their demise. Well worth the read for a number of good reasons.
What do we take for civilizon? We often are so humanicentric. Shouldn't we count ants and termites as civilization? I saw there is a reference about a book on ants in this thread.
The same is true for advanced galactic civilization: we are so ignorant of it, of what life is and what should or not qualify as living being. What is intelligence and wisdom? Recognition of plant communication is so recent, what lesson do you take out of it? How many dimensions actually encompasses us and how do they interact?
Take the Fermi paradoxes. Let's say your are some kind of very advanced civilization so advanced you know how to deal with all your civilization need to ensure perpetual sustainable forcastable needs of your civilisation. Let's say you manage to do that in a parcimonic way, avoiding to reveal your existence to other potentially hostile exogenous civilisations. Let's say that you are on top of that able and willing to explore other civilisations. At least in a first time in a way most likely undetectable. So your exploration project lead you to earth in a way like the hologram guy in code quantum. Would humans be the most interesting topic of interest for you? If so, would you see them as species you would think that you would label as wise, intelligent? Would it worth to decipher their language and try to give them some advises, with which chance that they would be followed? Given the way we treat each other and how we treat the rest of the biosphere, what opinion would you have of our species, seriously? Then, wouldn't it some form of wiseness to not reveal yourself until the species proves able to overcome the challenge of leaving peacefully and in harmony with the rest of the cosmos, or goes extinct, or destroy it if it seems to evolve toward a possible form of threat? After all, for such an advenced civilization, spawning a distinct civilization far less advenced such as us, or other forms of life/entity should be a peace of cake, so this would be no big loss, would it?
The biggest arguement against this is that we know a lot of minerals (iron etc) we're deposited before any multicellular life formed on earth. In a few short millenia we've used most of those resources. By extension, if someone was here before us, they'd have used the same deposits and we wouldn't have found them.
We already have a layer of radioactive deposits that's used as a boundary of the nuclear age.
If The Event happens now then I imagine nuclear waste dumping sites (which often try to account for deterring far future exploration) and plastics in regular rubbish dumps would be indicators of our civilisation.
Natural reactors were in my mind when writing this, thinking perhaps one can engineer a reactor but it appear to be natural. The thought went no further.
Desert glass has fooled people before too I think.
The problem people are complaining about in the comments is the tendency of many science journals lately to use their articles as undercover delivery vehicles for political messages in the guise of investigating something else.
If I had no agenda other than looking for evidence of pre-human technological civilization, I would focus on artifacts, as most people would. That is how we have found almost all ancient civilizations. You can't have even a slightly advanced civilization without creating big, hard objects such as rock or concrete or metal. Even a rather poor SE Asian town of 100,000 people out in the jungle will leave some fossils where their cheap, concrete buildings stood that, a billion years from now, may still exist and appear clearly non-organic (fossilized basements with pipes, for example). And if the civilization was "technological", it was probably populated enough for many such towns to have existed, at least one of which would probably have exposed fossils somewhere.
Of course asteroid strikes and plate tectonics could have buried it, and it's an interesting question where you might look for a city built a billion years ago, but there would probably be a lot more column inches devoted to solid artifacts, fossils, and questions like these than to climate change if the only thing on these scientists' agenda really was the question they claim.
I don’t think you can dismiss the problem of plate tectonics so easily. Vast amounts of the former surface of the earth are now several kilometres under our feet. That’s not something you can wave away.
Also it’s not reasonable to compare species fossil hunting with artefact hunting as equivalent. T-Rex as a species existed for 18 million years, with total cumulative population numbers estimated in the trillions or thousands of trillions across huge geographic areas and time spans. We have fossil fragments for only 50 individuals. That’s a staggeringly minuscule sample for a species spread out over a considerable span in both time and space.
An ancient civilisation might have existed for only a few thousand years, less than the blink of a geological eye. Unless you were to look at exactly the right strata at exactly the right layer you’d miss them completely. As a result it makes much more sense to look at environmental level effects, massively expanding the scope of your available evidence.
You're not likely to have much evidence to show of a civilization a billion years ago if all you have is excess carbon dioxide that might be due to any number of natural phenomena: forest fires due to overgrowth followed by drought, asteroid strikes thawing the tundra or whatever. Good luck claiming ancient civilizations if all you have is "a lot of organic material returned the CO2 to the atmosphere" but with no artifacts or anything else to show.
Now, I'm just using a billion years as a huge stretch to make it harder to find the artifacts I'm talking about. Anything within a 100M would be leaving fossils of all sorts of junk. A fossilized piece of an obviously artificial concrete building or bridge would be solid evidence and clearly Plan A compared to arguments about the cause of ancient CO2 fluctuations if you are purely interested in evidence of ancient civ.
Carcasses of tyrannosaurs were small, biodegradeable and tasty though, so their preservation was the rare exception rather than the rule. It would be rather harder to miss evidence of industrial cities of tens of millions of people spread across entire continents, many of which have not been subsumed by plates.
Most of the skeletons of the ancient Egyptians aren't found, but their pyramids are very much in evidence, and this was a civilization far too small and unsophisticated to leave obvious traces in the form of global warming.
I don't think we can rule out the possibility that past species used tools and communicated in ways which resemble human language, but if they'd been numerous and advanced enough to disrupt the climate with their Industrial Revolution, one can reasonably assume remnants of some of its products more substantive than evidence of temperature fluctuations or nitrate residues would exist.
Easier to get excited by false positives by widening the search space though: the same geological forces capable of disappearing nations are surely capable of causing temperature anomalies.
But enviromental effects billions of years ago could have be by any cause. They might indicate something, but much more solid would be real artifacts. Structures. Chemical compounds, etc.
But yes, the question is, what trace would our civilisation leave, if abandoned today, in a billion years, if the tectonic plates move in those timescales?
That's true, but we are actually reasonably good at identifying those causes, as the examples in the article show. For example the Paleocene-Eocene Thermal Maximum was also caused by a huge release of stored carbon, but over a 50,000 year period the per-year rate of release was tiny compared to our rate of output over the last few centuries. It is also associated with evidence of volcanism and geological uplift. Other causes would also leave other traces.
Nobody is saying that carbon release by itself just as a single undifferentiated data point proves anything. Of course there can be other explanations, those possible explanations are discussed in the paper. These criticisms are clearly well known to the authors, addressed in the paper and contextualised by the evidence. But it's only one dimension of evidence, and I don't think dismissing it is so easy or useful.
In a micrometeorite environment, they'll last a million years at most. All that will be left after a million years is a curious and anomalous concentration of metallic particles. After a billion years it will be buried and very easy to miss.
Possibly objects in an L4/L5 lagrange point as well.
Though I couldn't find an answer on whether those are stable on geological time scales, Earths only Trojan has been there for thousands of years but that isn't 60 million either.
Something I remembered from visiting Stonehenge a long time ago: the standing stones are impressive things, having been there for about four thousand years or so if memory serves. But also in the surrounding area are piles of dirt from approximately the same era. I wasn't expecting that.
It seems that every non-trivial modern construction project leaves behind a pile of dirt somewhere, usually as an unintentional side-effect rather than an end in itself. And these piles of dirt it seems stick around for a really long time if no one goes out of their way to flatten them back out.
I remember once reading about someone, I think he was a bored meteorologist in the wilderness of Alaska with a bulldozer and a lot of time on his hands. The story goes that he used the bulldozer to write something offensive (I don't think the story said what, exactly) and the local legislature chose not to do anything about it because then the offensive message would be part of the official records of the legislature. Maybe it's an urban legend; I wasn't able to find it with a quick google search. But I'd like to think his message will be visible from space long after most modern constructions have been torn down or destroyed by the slow process of time.
I guess few consider feasible a "wakanda" hypothesis. Maybe these guys somehow managed to survive in few numbers through the million of years since their civilization decline, and they'are around us, hidden in plain sight.
Around 1400, a giant base - thousands of "old" people - in the middle of Greenland or Antarctica would have been almost 100% unreachable / undetectable for that moment's human technology.
Right now there could be a giant space station around Neptune or somewhere in the outer ring of the solar system and we could barely notice it as an asteroid doing funny stuff (lights with no sunlight reflections!), if we got lucky enough to get a blurry image somehow.
Maybe those out-of-the-solar system visitors are here not for us at all (no scouting), but they are here in their regular interchange with our older - highly advanced - cousins.
Think about it, didn't we try to do the same with some primitive human tribes in the Amazon? We just tried to left them alone as far as possible, to do their stuff and we thrive in our own civilization, far away from them.
A more advanced civilization of this solar system could be doing the same with us in Earth.
We say "out there is fully inhabitable" just as we said that
about Siberia or Alaska, or the Sahara. But now - with some technology help - there are thousands of humans living in those places (even if we have no NY city like settlements).
Yes, and if my grandmother had wheels she would be a bicycle.
Honestly dude, we barely have evidence for existence and you just invented a interplanetary civilization out of thin air. While it might be amusing to some, its slippery slope we have already fallen down and found anti-vaxxers down there. Please refrain from making these wild assertions, and if not at least put a disclaimer about where you got the theory from.
haha, I get it sounds really crazy, but we are talking about advanced genetic engineering spanning millions of years in the future, so I though this other crazyness couldn't be that much out of place.
You're quite right about the sources, tought
Just my imagination.
I've been inspired by an article I found here sometime ago.
We as species got almost wiped out several times. But, we managed to recover and we rebuilt everything from scratch.
What could have happened if in the meantime of our recovery, some other species could have evolved (that's somehow happened with the Neanderthals)?
How Human Beings Almost Vanished From Earth In 70,000 B.C.
I think they are superpositions if two types of graph. First the left hand and bottom graphs. The blue graphs are concentrations of 13C isotope from various sources in the ecosystem. The red graphs are estimates of global temperature in degrees centigrade. Both types of graph are shown as deviations from the long term mean.
So what they show is that as 13C isotope levels drop, global temperatures rise. The drop in 13C concentrations is presumably because carbon from fossil fuels has extremely low isotope content because it mostly decayed, so as the proportion of fossil fuel carbon in the ecosystem rises isotope concentrations fall.
For the right hand graph red and blue are both isotope tracks, one is carbon the other is oxygen, which is being used as a proxy for temperature.
Too many presumptions about the inherent logic of how we structure things prevents us from seeing those who were not subject to this logic and it’s blind spots
Seems plausible that a sufficiently small and dim object could remain unobserved by humans, but if we’re considering objects from millions or even billions of years ago, I’m not sure the orbit would have remained stable.
There's no way for a satellite to orbit the Earth over geologic time scales.
Even geosynchronous and geostationary orbits degrade over time (though time scales extend to ten thousand years and longer).
Micrometeorites would shred any satellite to pieces and decay from thermal stress and radiation would basically turn satellites to dust over time (again - think millions of years).
I imagine archeologists digging up some ancient texts, written in a very sophisticated language,which eventually get translated and it turns out to be :" 101 social media tricks you can use to boost your business".
Yes, I'm fairly convinced that at some point some ancient civilization even more advanced than our own existed...then they invented social media and it all collapsed.
Bookkeeping of sorts is extremely old activity.I'm sure as soon as someone said ' you owe me 5 cows.No I don't,we settled last year' a need for bookkeeping was born.
I was just thinking that. Why even bother turning on comments if that's what happens? Maybe the final traces of our civilization will be a fossilized hard drive with some internet comments on it.
Possibly because nobody who actually reads scientific articles recreationally or for work will read the comments or at least won't consider them a serious discussion. However, leaving the comments off would likely cause those disagreeing to claim it's an "echo chamber" and push them to spread the article with quote tweets about how bad it is, causing much more of a storm. Letting people air their crazy theories is easier than having to deal with them getting built up until your publication is flooded with letters asking to stop whatever perceived malicious agenda you've got.
Maybe we should be looking for something else. Some different kinds of signs.
If -we- wanted something to outlast us, what would we build?
What can preserve information across literally millions, even billions for years?
Life.
The genomes, the bird songs, the designs some fish draw in the sea floor [0], that gland in octopuses that basically cause them to self-destruct within a short lifespan, but removing which allows them to continue living just fine?
Maybe even the growth rings of trees.
Could there be any clues encoded in those patterns? Is there no hint of genetic modification (I hesitate to say "intelligent design" because of its loaded implications related to religion) similar to what we ourselves are doing now?*
* (and have been doing for thousands of years, via selective breeding etc.)
[0] https://www.youtube.com/watch?v=hpdlQae5wP8