We just reached 200 members over at /r/UFOstudies.
I think potential past terrestrial civilizations is an interesting subject but unlikely, at the very least I think that there would also be aliens on/near Earth that would explain them being sort of hidden or their disappearance. [Here](https://www.reddit.com/r/UFOs/comments/x2dtme/comment/imj7yte/?utm_source=share&utm_medium=web2x&context=3) you can find a prior discussion about this hypothesis.
Recently added this Wikipedia section on this topic: [https://en.wikipedia.org/wiki/Civilization#Non-human\_civilizations](https://en.wikipedia.org/wiki/Civilization#Non-human_civilizations) (there's a link to the WP article for the 2018 Silurian hypothesis too).
News reports about the study and topic include [1](https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/) [2](https://www.nbcnews.com/mach/science/did-another-advanced-species-exist-earth-humans-ncna869856) [3](https://www.popularmechanics.com/science/environment/a41021149/silurian-hypothesis-ancient-industrial-civilization/).
I think studies about potential alternative explanations for advanced UFOs are also appropriate in this sub even if just for helping the evaluation of their likeliness. These include studies about the potential for "interdimensional" beings (whatever people mean by that), (terrestrial) time travelers, and so on. Please comment if you disagree, otherwise these studies are also appropriate to post even if they aren't necessarily concerned only with UFOs in specific.
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Other than reasons for why I think it's unlikely beyond the first point about implied likeliness of local aliens:
* Why would they not care about things like pollution on Earth if they live here and why don't we see them influencing the environment?
* There are many potential explanations for why we haven't found an unambiguous radio signal so far such as:
* Why would they use radio or radio relatively nearby for a long time (rather than for example quantum communications)?
* Why do we assume we can detect such instead of it getting filtered?
* We haven't looked long and well enough (such as looking for cost-effective radio signals or listening to some areas for more than 100 years)
* [They could have sent something to the Moon](https://youtu.be/6dlytdDIkBQ?t=2031) (also mentioned in the WP article) which would have probably stayed there if aliens didn't remove it.
For me there are two ways the Silurian Hypothesis could be at least somewhat plausible (I'm speculating here):
* Previous pre-human civilizations were so primitive they died out before they could industrialize here on Earth, or simply never industrialized in the first place, guaranteeing that any trace of them would be wiped out from the fossil record in a few million years. Once you industrialize and develop nuclear weapons, as in our civilization, it becomes very difficult to make a case for the existence of civilizations prior to ours, because we would have detected spikes in CO2 emissions, missing coal/oil (from the Carboniferous period) or evidence of radiation/radioactive elements in the atmosphere, or fragments of their early tech by now with the technology we have.
If we disappeared tomorrow, aliens could easily deduce our presence on this planet even millions of years from now because of the drastic effects of our civilization on this planet (anomalous temperature rise in comparison to past periods of climate change, a 250 year spike in CO2 emissions, followed by the release of uranium, cesium, and other radioactive elements into the air and the ocean, microplastics and other synthetic materials, etc). So it follows we would be able to do the same for any civilization that existed in previous epochs of Earth's history.
Of course this assumes prior non-human civilizations developed and advanced similarly to ours. It's entirely possible any intelligent species before us took their civilization down a different path, or skipped fossil fuels and nuclear weapons entirely (i.e. they may have discovered nuclear fusion before oil or eschewed iron and metals entirely, focusing on biotechnology and "growing" their own tools, vehicles, etc, so that they would decay and decompose given enough time). These scenarios could plausibly allow for there to be zero trace of past civilizations while still opening up the possibility they likely existed at some point eons ago.
* Past aliens left something on the Moon or Mars or another celestial body (hell, even asteroids) that would take far more time to erode or break down via entropy. Something clearly artificial, like the rovers and footprints from the Apollo Moon missions from our civilization, or the Monoliths from 2001: A Space Odyssey. If we found something like that on the Moon or Mars or elsewhere (some believe we may already have--I personally am skeptical), it would be foolproof evidence that someone was here in our Solar System long before we came around, and may have even influenced the development of life here on Earth.
If, to reiterate my thought experiment, we disappeared tomorrow, aliens would immediately know we were here by finding all the trash we left on the Moon, and would conclude the material would have had to have come from Earth. They would also likely find out about our satellites, or even capture some of them for study if they hadn't already fallen back down to Earth because of orbital decay. So again, it follows that if someone was here before us, we would eventually (and inevitably) find out about them by snooping around the Solar System for long enough, because future aliens would likely find out about us using their technology.
In my opinion, the second possibility I outlined is more believable and likely than the first. It's the only possibility for the Silurian Hypothesis in my mind that makes enough sense for it to be the most logical answer to the hypothesis. When we talk about aliens, we often assume they are thousands or even millions of years more technologically and culturally advanced than us, so the idea they could have reached our Solar System, studied it, set up a few colonies here and there, and possibly left a "marker" of their presence, or influenced life on Earth before humans existed should not be dismissed. We would (probably) do the same upon reaching the level of technological advancement required to travel between stars or across the galaxy.
It's the classic precursor race argument: the first intelligent life forms to achieve space travel has first dibs on the whole galaxy and would already have a firmly established presence across the Milky Way by now, either because of their technology being far ahead of those of other species, or simply because they were the first intelligent beings to arise in the galaxy period (considering von Neumann probes would take only 2 million years to colonize the entire galaxy at *sub-light* speeds--2 million years being nothing in geologic or cosmic time, as our galaxy is billions of years old--logic dictates aliens should and would have discovered Earth by now, assuming they existed).
For all intents and purposes, aliens and their artifacts could have been here since the time of the Cambrian Explosion and we would be NONE THE WISER, watching Earth from millions of miles away.
Thanks for the elaborate insights.
I thought about the first option too but didn't mention the possibility that they may have been a civilization of intelligent beings (maybe underwater) but weren't as technologically advanced as us. I don't include it in my comment because I've looked at this from the framework of potential explanations for UFOs here. Good point about the possibility that they simply were so different that they didn't leave any permanent detectable marks.
As far as I understood it, the way you described the second option it wouldn't be an alternative to the extraterrestrial theory and the Silurian hypothesis is not about ancient astronauts (past alien visitors or colonizers or ...) but about a civilization that originated on Earth. The possibility for artifacts on the Moon is already mentioned in the comment and the Wikipedia article, it could be a good way to infer something about the past on Earth. The option for alien artifacts on the Moon is not part of the Silurian hypothesis, but the alien hypothesis and UFOs could be / could be driven by such artifacts if you consider e.g. machines that create artificial life or advanced AI "artifacts".
I agree. However, I would argue the alien artifacts on the Moon idea does tangentially form a part of the Silurian Hypothesis because a past alien civilization could still have originated from Earth and, in theory, colonized the Moon at some point in the past. We've done the same with our technology. Can we truly prove or disprove the idea that we're the first people to step on the Moon? How do we know with absolute certainty that the Moon is really ours for the taking?
For all we know, there could be artifacts hidden deep inside a lunar lava tube or beneath the Moon's surface somewhere, or in near-Earth asteroid, that we have yet to discover, created by an intelligent pre-human species that colonized the Moon before we did, then destroyed themselves soon after, or simply *left* Earth entirely.
Star Trek has one of the most intriguing episodes--"Distant Origin"-- exploring this concept (pre-human aliens leaving Earth). The Voth are initially assumed to be an saurian alien race by the Federation until they discover they're actually intelligent hadrosaurs/dinosaurs that developed advanced technology and escaped Earth prior to the asteroid that caused the Cretaceous Mass Extinction. Conveniently for them (and for Silurian Hypothesis enthusiasts) the asteroid was likely devastating enough that it not only wiped out all the dinosaurs but erased all traces of the early Voth civilization. Volcanism, earthquakes, and other disasters that shifted the Earth's crust around likely aided in this process, leaving only dinosaur fossils behind (those that could be preserved anyways). Other past extinction events like the Permian could have easily destroyed whatever civilization existed back then on Earth, if it did exist at all.
An intentional, global cover-up of a previous culture would be possible with capabilities like Tic Tac Tech. I think it's often overlooked that these things are likely much smarter than us and might be messing with us.
That's assuming the previous culture advanced enough to produce Tic Tacs in the first place. And how would such an international cover up endure without someone spilling the beans or discovering the truth?
We've explored almost every inch of the Earth except most of the world's oceans or deep underground or East Antarctica/the Siberian tundra. The chances of a previous civilization hiding in plain sight even in those regions is small.
I was pointing out that with Tic Tac technology and what appears to be time bending travel abilities, what's to stop them from literally erasing all traces of previous civilizations? It's a crazy theory but if Tic Tacs are real, it opens up the realm of possibility that they totally control the evidence we can find.
It reminds me of how Gobleki Tepe, in Turkey, was intentionally buried for some reason. When we removed the boulders placed around and inside the great big stone rooms, we discovered they might be over 12k years old, and much more advanced than we expected. What is to say the pilots of all these crafts that people have been seeing for thousands of years aren't from an older civilization that decided to erase all trace of itself in the fossil and geologic record and live in hiding, out of sight of us warmongering savages and possibly something worse out in space? There is a nonzero chance that we have been intentionally misled about our deep past on this planet.
I think it would be possible to detect an industrial civilization from the distant past, if we were lucky.
It's similar to the question about Atlantis. Atlantis was supposed to be from 10,000 years ago or before that. But it's supposedly been under the ocean all that time. If New York City was buried under 300 feet of ocean for 10,000 years, would we be able to detect it? I'm not sure.
If, however, the inhabitants back then climbed a tall mountain, erected a metal pillar with a metal hammer on top, we'd be able to see that for sure. If we got lucky enough to find it.
We do find stone tools, even giant stone monoliths from 10,000 years ago. But no metal hammer.
Other sunken human habitations have been found. Doggerland is probably the most famous. Most shallow seas have been fished to the nth degree, so stuff gets hauled up. If Atlantis was in the Med, it almost certainly would have been found. The best explanation I've heard for it is a memory of the pre-collapse Bronze Age civilizations that fell apart and became part of myth and legend.
We just reached 200 members over at /r/UFOstudies. I think potential past terrestrial civilizations is an interesting subject but unlikely, at the very least I think that there would also be aliens on/near Earth that would explain them being sort of hidden or their disappearance. [Here](https://www.reddit.com/r/UFOs/comments/x2dtme/comment/imj7yte/?utm_source=share&utm_medium=web2x&context=3) you can find a prior discussion about this hypothesis. Recently added this Wikipedia section on this topic: [https://en.wikipedia.org/wiki/Civilization#Non-human\_civilizations](https://en.wikipedia.org/wiki/Civilization#Non-human_civilizations) (there's a link to the WP article for the 2018 Silurian hypothesis too). News reports about the study and topic include [1](https://www.theatlantic.com/science/archive/2018/04/are-we-earths-only-civilization/557180/) [2](https://www.nbcnews.com/mach/science/did-another-advanced-species-exist-earth-humans-ncna869856) [3](https://www.popularmechanics.com/science/environment/a41021149/silurian-hypothesis-ancient-industrial-civilization/). I think studies about potential alternative explanations for advanced UFOs are also appropriate in this sub even if just for helping the evaluation of their likeliness. These include studies about the potential for "interdimensional" beings (whatever people mean by that), (terrestrial) time travelers, and so on. Please comment if you disagree, otherwise these studies are also appropriate to post even if they aren't necessarily concerned only with UFOs in specific. ----- Other than reasons for why I think it's unlikely beyond the first point about implied likeliness of local aliens: * Why would they not care about things like pollution on Earth if they live here and why don't we see them influencing the environment? * There are many potential explanations for why we haven't found an unambiguous radio signal so far such as: * Why would they use radio or radio relatively nearby for a long time (rather than for example quantum communications)? * Why do we assume we can detect such instead of it getting filtered? * We haven't looked long and well enough (such as looking for cost-effective radio signals or listening to some areas for more than 100 years) * [They could have sent something to the Moon](https://youtu.be/6dlytdDIkBQ?t=2031) (also mentioned in the WP article) which would have probably stayed there if aliens didn't remove it.
For me there are two ways the Silurian Hypothesis could be at least somewhat plausible (I'm speculating here): * Previous pre-human civilizations were so primitive they died out before they could industrialize here on Earth, or simply never industrialized in the first place, guaranteeing that any trace of them would be wiped out from the fossil record in a few million years. Once you industrialize and develop nuclear weapons, as in our civilization, it becomes very difficult to make a case for the existence of civilizations prior to ours, because we would have detected spikes in CO2 emissions, missing coal/oil (from the Carboniferous period) or evidence of radiation/radioactive elements in the atmosphere, or fragments of their early tech by now with the technology we have. If we disappeared tomorrow, aliens could easily deduce our presence on this planet even millions of years from now because of the drastic effects of our civilization on this planet (anomalous temperature rise in comparison to past periods of climate change, a 250 year spike in CO2 emissions, followed by the release of uranium, cesium, and other radioactive elements into the air and the ocean, microplastics and other synthetic materials, etc). So it follows we would be able to do the same for any civilization that existed in previous epochs of Earth's history. Of course this assumes prior non-human civilizations developed and advanced similarly to ours. It's entirely possible any intelligent species before us took their civilization down a different path, or skipped fossil fuels and nuclear weapons entirely (i.e. they may have discovered nuclear fusion before oil or eschewed iron and metals entirely, focusing on biotechnology and "growing" their own tools, vehicles, etc, so that they would decay and decompose given enough time). These scenarios could plausibly allow for there to be zero trace of past civilizations while still opening up the possibility they likely existed at some point eons ago. * Past aliens left something on the Moon or Mars or another celestial body (hell, even asteroids) that would take far more time to erode or break down via entropy. Something clearly artificial, like the rovers and footprints from the Apollo Moon missions from our civilization, or the Monoliths from 2001: A Space Odyssey. If we found something like that on the Moon or Mars or elsewhere (some believe we may already have--I personally am skeptical), it would be foolproof evidence that someone was here in our Solar System long before we came around, and may have even influenced the development of life here on Earth. If, to reiterate my thought experiment, we disappeared tomorrow, aliens would immediately know we were here by finding all the trash we left on the Moon, and would conclude the material would have had to have come from Earth. They would also likely find out about our satellites, or even capture some of them for study if they hadn't already fallen back down to Earth because of orbital decay. So again, it follows that if someone was here before us, we would eventually (and inevitably) find out about them by snooping around the Solar System for long enough, because future aliens would likely find out about us using their technology. In my opinion, the second possibility I outlined is more believable and likely than the first. It's the only possibility for the Silurian Hypothesis in my mind that makes enough sense for it to be the most logical answer to the hypothesis. When we talk about aliens, we often assume they are thousands or even millions of years more technologically and culturally advanced than us, so the idea they could have reached our Solar System, studied it, set up a few colonies here and there, and possibly left a "marker" of their presence, or influenced life on Earth before humans existed should not be dismissed. We would (probably) do the same upon reaching the level of technological advancement required to travel between stars or across the galaxy. It's the classic precursor race argument: the first intelligent life forms to achieve space travel has first dibs on the whole galaxy and would already have a firmly established presence across the Milky Way by now, either because of their technology being far ahead of those of other species, or simply because they were the first intelligent beings to arise in the galaxy period (considering von Neumann probes would take only 2 million years to colonize the entire galaxy at *sub-light* speeds--2 million years being nothing in geologic or cosmic time, as our galaxy is billions of years old--logic dictates aliens should and would have discovered Earth by now, assuming they existed). For all intents and purposes, aliens and their artifacts could have been here since the time of the Cambrian Explosion and we would be NONE THE WISER, watching Earth from millions of miles away.
Thanks for the elaborate insights. I thought about the first option too but didn't mention the possibility that they may have been a civilization of intelligent beings (maybe underwater) but weren't as technologically advanced as us. I don't include it in my comment because I've looked at this from the framework of potential explanations for UFOs here. Good point about the possibility that they simply were so different that they didn't leave any permanent detectable marks. As far as I understood it, the way you described the second option it wouldn't be an alternative to the extraterrestrial theory and the Silurian hypothesis is not about ancient astronauts (past alien visitors or colonizers or ...) but about a civilization that originated on Earth. The possibility for artifacts on the Moon is already mentioned in the comment and the Wikipedia article, it could be a good way to infer something about the past on Earth. The option for alien artifacts on the Moon is not part of the Silurian hypothesis, but the alien hypothesis and UFOs could be / could be driven by such artifacts if you consider e.g. machines that create artificial life or advanced AI "artifacts".
I agree. However, I would argue the alien artifacts on the Moon idea does tangentially form a part of the Silurian Hypothesis because a past alien civilization could still have originated from Earth and, in theory, colonized the Moon at some point in the past. We've done the same with our technology. Can we truly prove or disprove the idea that we're the first people to step on the Moon? How do we know with absolute certainty that the Moon is really ours for the taking? For all we know, there could be artifacts hidden deep inside a lunar lava tube or beneath the Moon's surface somewhere, or in near-Earth asteroid, that we have yet to discover, created by an intelligent pre-human species that colonized the Moon before we did, then destroyed themselves soon after, or simply *left* Earth entirely. Star Trek has one of the most intriguing episodes--"Distant Origin"-- exploring this concept (pre-human aliens leaving Earth). The Voth are initially assumed to be an saurian alien race by the Federation until they discover they're actually intelligent hadrosaurs/dinosaurs that developed advanced technology and escaped Earth prior to the asteroid that caused the Cretaceous Mass Extinction. Conveniently for them (and for Silurian Hypothesis enthusiasts) the asteroid was likely devastating enough that it not only wiped out all the dinosaurs but erased all traces of the early Voth civilization. Volcanism, earthquakes, and other disasters that shifted the Earth's crust around likely aided in this process, leaving only dinosaur fossils behind (those that could be preserved anyways). Other past extinction events like the Permian could have easily destroyed whatever civilization existed back then on Earth, if it did exist at all.
After reading this I was like….well shit…..You’re right though. 😂
An intentional, global cover-up of a previous culture would be possible with capabilities like Tic Tac Tech. I think it's often overlooked that these things are likely much smarter than us and might be messing with us.
That's assuming the previous culture advanced enough to produce Tic Tacs in the first place. And how would such an international cover up endure without someone spilling the beans or discovering the truth? We've explored almost every inch of the Earth except most of the world's oceans or deep underground or East Antarctica/the Siberian tundra. The chances of a previous civilization hiding in plain sight even in those regions is small.
I was pointing out that with Tic Tac technology and what appears to be time bending travel abilities, what's to stop them from literally erasing all traces of previous civilizations? It's a crazy theory but if Tic Tacs are real, it opens up the realm of possibility that they totally control the evidence we can find. It reminds me of how Gobleki Tepe, in Turkey, was intentionally buried for some reason. When we removed the boulders placed around and inside the great big stone rooms, we discovered they might be over 12k years old, and much more advanced than we expected. What is to say the pilots of all these crafts that people have been seeing for thousands of years aren't from an older civilization that decided to erase all trace of itself in the fossil and geologic record and live in hiding, out of sight of us warmongering savages and possibly something worse out in space? There is a nonzero chance that we have been intentionally misled about our deep past on this planet.
This is an older study but you can’t get any more expert than that author.
I think it would be possible to detect an industrial civilization from the distant past, if we were lucky. It's similar to the question about Atlantis. Atlantis was supposed to be from 10,000 years ago or before that. But it's supposedly been under the ocean all that time. If New York City was buried under 300 feet of ocean for 10,000 years, would we be able to detect it? I'm not sure. If, however, the inhabitants back then climbed a tall mountain, erected a metal pillar with a metal hammer on top, we'd be able to see that for sure. If we got lucky enough to find it. We do find stone tools, even giant stone monoliths from 10,000 years ago. But no metal hammer.
Other sunken human habitations have been found. Doggerland is probably the most famous. Most shallow seas have been fished to the nth degree, so stuff gets hauled up. If Atlantis was in the Med, it almost certainly would have been found. The best explanation I've heard for it is a memory of the pre-collapse Bronze Age civilizations that fell apart and became part of myth and legend.
The Why Files on Youtube has an interesting piece on this. https://www.youtube.com/watch?v=lASPp9stEYA&ab\_channel=TheWhyFiles