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So maybe just stick right to the paper itself and its clearly stated motivation?
> Perhaps unusually, the authors of this paper are not convinced of the correctness of their proposed hypothesis. Were it to be true it would have profound implications and not just for astrobiology. However, most readers do not need to be told that it is always a bad idea to decide on the truth or falsity of an idea based on the consequences of it being true. While we strongly doubt that any previous industrial civilization existed before our own, asking the question in a formal way that articulates explicitly what evidence for such a civilization might look like raises its own useful questions related both to astrobiology and to Anthropocene studies. Thus, we hope that this paper will serve as motivation to improve the constraints on the hypothesis so that in future we may be better placed to answer our title question.
[0]https://www.cambridge.org/core/journals/international-journa...
Places where there is suddenly a vast collection of foreign rocks from the other side of the world that can't be explained by glaciers.
Radioactivity from nuclear tests that can't be explained by stellar phenomena and leave a layer of weird isotopes and isotope ratios all around the world, as we already have done.
And while we aren't to the point we'd have found this quite yet necessarily, evidence on the Moon where unlike Earth evidence probably would in fact persist for millions of years, especially if it ever attained any scale, e.g., "a large complex of cities" might still leave a visible mark on the surface easily visible to modern satellites and clearly with no other explanation available as to what caused it.
People get stuck on the idea that the only way to determine there was intelligent life earlier is to find a super complicated artifact which obviously can't survive, but there are footprints we've left in the world that are way, way larger than a cell phone or even a major city.
I don't find it hard to believe we've lost entire human civilizations. In fact I'd call it the smart bet. Maybe those civilizations were even a bit more sophisticated than we'd have thought, with maybe an earlier and entirely unknown Iron Age popping up somewhere for some period of time or something. But this is the first major technological civilization this planet has ever seen, even across geological time scales. And those lost human civilizations never reached to the level where they took all the easy resources like we have, because if they had, we wouldn't be able to get them. Some resources we call "non-renewable" do replenish on a few million year time scale, but we also pull lots of resources out of billion-year-old rocks, such as copper mines in northern Michigan which are pulling resources out of pre-Cambrian rocks. Clearly nobody else has been there, at scale.
Why is it obvious that none of them can survive? Ordinary bones can become rocks (fossils) that are preserved. If mining of iron ore is visible, things would have been made out of iron -- wouldn't a large structure made out of iron leave some trace? Or even a small one? Why are there dinosaur fossils galore, but not so much as a pre-human fidget spinner to be found?
Not really, because none of this passes the smell test if you know even a tiny bit about geology and paleontology. The most solid arguments are religious texts, there is not really any substance other than that.
Nah, you way off on that, coastlines have remained relatively same last million years, def not subducted into an ocean trench
We have plenty of fossil evidence from, from your example, a million year old hominids. Far more than we would need to expect to see evidence of civilization.
Subduction makes up for a tiny tiny proportion of where coastal land "goes" in any age.
You'd need an enormous set of coincidences for a past civilization of hominids to go unnoticed.
Jokes aside, what is the evidence, beyond "Ancient mystical texts"?
[0] http://www.myths.com/pub/fiction/science-fiction/Asimov/Nigh...
https://en.wikipedia.org/wiki/Falsifiability
I know about Yellowstone, Campi Flegrei, etc, but I haven't heard about a supervolcano below the Atlantic. What's that referring to?
Our knowledge is becoming holographic such that to prevent the reemergence of civilization one would have to wipe out all of us at once.
So there could have been this hypothetical civilization 55 million years ago already. And they've only just disappeared (if they did) 10'000 or so years ago? Without a trace?
Also, no, a conspiracy cannot be the answer to a question we've not yet asked. The word has a clear meaning, it requires people to conspire to hide something from you.
"Ancient mystical texts hint at earlier creation, the life that preceded the Garden, prequels to Genesis. These incarnations are not reported in the Bible because they are none of your goddamn business, but the evidence is everywhere. Some students of conspiracy believe there was a time when lizard people shared the earth with modern men, the older race dying as the younger emerged from the forest. The last of the lizards were worshipped as gods; these were the deities of ancient India and Greece. The technology—weapons and machines—created miracles. You can see the lizard kings in carvings from Mesopotamia, the oldest historical records, where humans bow before reptile men. You find them again in the Torah, where they appear as Nephilim..."
dude wind hundreds of thousands of years into future, sands of time, etc. modulo two warring biological descendants of humans not full diff species tho
I also use the Carboniferous Period as a metric as to why "Advanced alien life" isn't more abundant (and I believe it should be factored into the Fermi equation)...
All those trees growing, soaking up sun, dying and just laying there to be compressed and buried without anything to decompose them, and then humans using them like solar batteries to power civilization (i.e. burning the coal), is one of those million-to-one things that enabled the human race to develop beyond basic society.
We needed all that coal and oil (and gas) based power to get to the point - industrially and technologically - where we could even build solar panels or nuclear to replace them, so its not like you could start from first principals and jump straight to modern power generation either.
The odds that the same sequence of events - fungus and bacteria not having the tools to decompose lignin (or whatever the alien equivalent is) - to happen on an extra-solar planet is ... pardon my pun ... astronomical :D
(yes, I used a dash to separate ideas in a sentence, deal with it...)
I do not understand this statement, I thought an area in Quebec was around 3 - 4 billion years old. I looked, seems Australia may have the oldest area:
https://www.bbc.com/travel/article/20220126-is-the-pilbara-t...
But I say the article could be true, but the only issue I have is the large dinos. I would think they could be an impediment to any organized settlements.
One other thing, didn't most of our fossil fuels come from the Carboniferous era ?
https://en.wikipedia.org/wiki/Carboniferous
And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left? Like, billions of individuals, cities, factories, metals, concrete, mines, wells, roads and bridges and tunnels, stone sculptures!, plastic, waste dumps, farms, agricultural land, billions and billions of artifacts of all materials, most of them entirely artificial. All gone because "nothing resists 400 my" and, "oh btw, check this dinosaur footprint and this fossilised piece of skin, how cool"?
The fossils we do have are of highly successful species in that geography. It’s a matter of chance, leaving behind a fossil, after all.
And unlike biological matter that can fossilize, industrial structures etc do not. All our manufactured stuff has very short life once it reaches the crust and starts getting compacted.
The more time you add, the better the odds we’d find this evidence lost.
And if this wasn’t a global, but more localized pre-human civilization, the evidence would be thinner still.
Which is why this isn’t a scientific hypothesis really. It’s more showing you the limits of scientific inquiry into the deep history of Earth.
I think this is it: the point of this argument is to inspire some awe in the listener, making them realise how vast Earth's time is compared to our horizons.
But in practice, the argument is wrong. A dead animal's skin is expected to lasts weeks to months- and yet we have fossilised specimens. A footprint typically lasts hours, and yet we have ones that are hundreds of millions of years old. Even if the expected lifespan of our artifacts is nothing in comparison with these timespans, a small percentage of artifacts will either be preserved or leave recognisable traces- exactly as it happened for soft tissues and footprints. It's extremely naive to think that none of this will leave traces.
The counter-counter argument is that while we’ve been here for a comparative blink of an eye, we’ve left behind 4 orders of magnitude more stuff than just nests, bones, and a feather or two.
I do find it difficult to believe that we would not leave enough fossil and mineral evidence for future paleontologists to find. I get that the surface will churn, but layers of rock routinely become exposed, revealing the geological history of the area. No tea cup shards, no impressions of rusted cars in the mud, no concentration of metal in strangely rectilinear formations that suggests skyscrapers?
While there would probably very little direct evidence of humans after millions of years, there would probably be at least some anomalous evidence someone could find.
So current human population is 400 thousand times the maximum T-rex population at any one time. A few decades are enough to produce more human individuals than the entire T-rexes history. We also have the ability to go (and die) pretty much anywhere, so there will be human skeletons in every crevice, depth and environment on Earth. We also produce an absolutely staggering amount of artifacts of all kinds, from plastic straws to giant tunnels and artificial caves. There are zero chances an advanced civilisation on Earth won't be aware of us in 400 million years.
Plastic will be gone in ~1000 years,
https://www.activesustainability.com/environment/waste-plane...
tunnels and artificial caves in a few million years at most as they are compressed by the weight of the rocks above them ("tunnel squeezing").
If humanity vanished today, in 1 million years almost all of our artifacts would be gone or burned under miles of subduction.
In 10 million years there would literally be nothing left.
That is completely incorrect. We have sedimentary rocks from 100 M years ago on the Earth’s surface right now, that never underwent any kind of subduction.
Subduction only occurs at plate boundaries and is not nearly this fast. Continental plates float on top like foam and do not get subducted. It's the oceanic plate that is created at mid-ocean ridges and gets subducted at the margins.
Also, just as we "engineered" animals and plants through selective breeding, previous animals/plants could have been the results of selective breeding by a previous civilization: There'd be no way to tell just as there'd be no way to tell our "tampering" a few million years in the future.
How so? We know how it forms, there is no real gap in understanding there. What could lead to the kind of distribution of oil and gas fields we can observe?
I mean, would an ant walking on a highway be able to tell that it's artificial?
400 million years ago is as distant as the stars. The Earth was a different planet then, in a sense.
It’s also yet another Fermi paradox answer. Even if our civilization lasts for millions of years, that’s a blip. We are searching both space and time and both are incomprehensibly vast.
As such it seems impossible for life to have reached interstellar travel anywhere in the Milky Way before at most a few million years ago, otherwise we would see it.
Which is weird because life surely can’t be that rare in the entirety of space time.
Of course the galaxy could be teaming with non interstellar life, but once you reach mankind’s level of sentience and technology it dormant seem a massive jump to interstellar, and once that happens there’s no way to put the genie back in the bottle.
This is what I always say to "Why haven't we found any aliens yet??"
Hell, we wouldn't even have known about the existence dinosaurs, lifeforms on THIS VERY PLANET, if we hadn't chanced upon their remains.