What if Humans Are NOT Earth's First Civilization? | Silurian Hypothesis

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We’re almost certainly the first technological civilization on Earth. But what if we’re not? We are. Although how sure are we, really? The Silurian hypothesis, which asks whether pre-human industrial civilizations might have existed.
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[@sethmaki1333]

Reminds me of the Star Trek: Voyager episode "Distant Origin" where the hero ship happens upon an ancient civilization on the other side of the galaxy that descended from hadrosaurs that left Earth 70 million years ago.

[@brennanr.697]

Scrolled way to far to find a comment mentioning that episode

[@TheJadeFist]

Ya, but if such a society existed, even if we never found evidence of it left on earth, might we find other evidence in our solar system though? Satellites would have lost or been flung from orbit over that long period, so probably nothing there. If it existed in mars it might have completely eroded by now, or been boiled over by lava when the planet was hotter and more volcanologically active. (it's a word now with it) Maybe something still exists there and is simply buried by millions of years of rust, but might be otherwise intact, or something taking wide paths around the solar system, like an early probe the kind we send out now. That probe would be the most likely to survive I think, but good luck finding a tiny piece of metal in the whole Oort cloud you don't' even know is there.

[@ianbrett3276]

It's a shame that they didn't follow up that episode with more on the Vo'th species as recurring guest aliens

[@UltimatePerfection]

​@@ianbrett3276If Prodigy is allowed to go past the second season, maybe we'll see more of them.

[@bannisher]

Everyone in this thread is awesome. LLAP

[@SF-fb6lv]

I think Silurian Hypothesis should be boiled down to: "Due to subduction, records of surface phenomena will be obscured over millennia" instead of the current: "an Industrial Civilization may have existed before humans existed". It is like modifying the belief that "A teapot might be orbiting Earth" to "It would be difficult to detect something as small as a teapot orbiting Earth".

[@stevelyman6917]

"The Brain Eaters," a 1958 horror film had a plot that revolved around an insect civilization from the Carboniferous creating a capsule to escape their refuge from deep underground. Also notable for featuring a pre-Trek Leonard Nimoy.

[@Pictureperfectroof]

Who’s making these movies? Someone knows something

[@Sir_Typesalot]

„They‘re already here, aren’t they?“ - „THEY have been here long before us, Mr. Mulder.“

[@georgemichelakis1202]

Always happy to find a fellow X-Files fan!

[@enotdetcelfer]

This is why we need to build a pyramid on the moon... you know future civilizations will be like, pyramids or it didn't happen.

[@ngud_gaming267]

One last prank before we go. True human activity

[@WayneMcDougall]

One asteroid takes it out ..

[@steve29384]

@@WayneMcDougallsame with earth

[@WayneMcDougall]

@@steve29384 on earth we don't wait for asteroids - just tectonic activity and erosion. The Moon is where you place your monolith.

[@stephanieworkman5110]

@@WayneMcDougallSo you’re saying…we need two pyramids on the moon.

[@Gnomezonbacon]

There was an episode of Star Trek Voyager about this. A dinosaur civ escaped before the asteroid hit and drifted around the galaxy for millions of years until a ship from the same homeworld stumbled into them on the other side of the galaxy.

[@MJG206]

Distant Origin.

[@MrClassicmetal]

How did those creatures manage to escape before the asteroid hit?

[@tmst2199]

Did they make it to another planet or just live in their cars for millions of years?

[@Obiter3]

Was a dinosaur driving the ship?

[@tmst2199]

@@Rich-hy2ey Anthopologists have modern humans emerging from Africa where their ancestors were presumably pretty well-suited.

[@davidtal523]

i really enjoy these episodes that dont contain overly complex math and phsyics that i cant remotely understand. this was interesting, and fun. thank you.

[@DanielVerberne]

I feel much the same. I have loads of curiosity about the world around us and enjoying learn - but I also feel my limits in regards to the technicalities of the underlying science. I'm definitely pro-science and much appreciate it's ability as a system of thought to enriching our knowledge, but I don't think much of my personal capacity to understand the details!

[@GSPV33]

Appreciate all of you at PBS Spacetime, your efforts (shoutouts to the animators & editors.) I also appreciate the community here.

[@pugofwarbr]

this reminds me of the Lovecraft's stories, basically Earth was invaded by different civilizations on the course of millions of years, all them sooner of later became extincts, or devolved, or literally just ghosts remains.

[@RickJaeger]

Lovecraft was writing at a time where he was engrossed by the booming new scientific understanding of "deep time," he thought it was fascinating, hence incorporated into his writing a radical, scientifically-inspired understanding of just how much older the Earth is than conventional wisdom (informed by written history and literalist biblical timelines) previously suggested.

[@yarpen26]

"At the Mountains of Madness" is my favorite Lovecraft's story, even if atypical of his writing in general (speaking of which, it's kinda weird to read such hard sci-fi coming out of a horror guy who's otherwise all about mystery and monsters). Sure, it's absurd to imagine artifical structures withstanding erosion over 30 million years, but it does serve the drama. Lovecraft is an aquired taste and while I absolutely don't recommend going through all of his stuff like I did, since much of it is pretty mediocre, especially from the 1920s, and even this story has its fair share of detractors who can't make their way through the endless paragraphs of descriptions, but if you want to pick anything by him, I'd say pick this one.

[@Mma12367]

If this is true it will explain the war between gods in many mythologies like Anunaki ,ashura vs devas ect it can really help us cause in those mythologies they all were different species not humans

[@yarpen26]

​@@Mma12367 They're all either humans or human-like mutants. The God of Christianity in neo-Platonian interpretation is more like an alien species than any of the other guys. There is not a shred of evidence to suggest that mythologized god wars were anything other than distorted recounts of conflicts between powerful chieftains from eons past.

[@Mma12367]

@@yarpen26 what do you mean by human mutants

[@DanielVerberne]

This fascinating concept brings to mind the famous sci-fi classic 'Nightfall' by Isaac Asimov and Robert Silverberg. In Nightfall, an alien race lives on a world that features not one but several suns. Each sun is up and visible at some part of the time each day and so the concept of 'darkness' is unknown and therefore terrifying to these aliens. In the story, astronomers make a prediction that a full eclipse will occur in the near future, exposing the alien civilisation to complete darkness. It is predicted that most of the aliens will go insane from the experience. Meanwhile in parallel to this storyline, the alien equivalent of geologists are exploring a dig site that uncover something shocking - a layer of carbon and ash buried under the current layer of habitation. The analysis suggest that the ash represents mass fires and destruction - of a previous 'cycle' of civilisation of that alien race. Further digs reveal something even more shocking - an undeniable pattern of wholesale civilisation destruction occurring with a definite period; over and over. It is eventually realised that the current civilisation of aliens on that planet is now 'almost due' for another collapse - and it looks like the forthcoming ultra-rare eclipse and descent into darkness may be the root of all of this. In short, Nightfall as a story contained a seed of the Silurian Hypothesis - what if our current 'advanced' civilisation isn't the first and indeed perhaps only represents the apogee of this particular 'instance' of human civilisation? Now I don't think there's any substance to that idea here on Earth, but nor do I know for sure either.

[@Bitchslapper316]

I think there is some evidence of it happening on earth. Why do most cultures on earth have stories dating back thousands of years about beings coming down from the sky with amazing abilities then calling them gods? How did humans spread across the globe then suddenly all develop agriculture and civilization separately at the same time? We're talking about cultures separated by thousands of miles and oceans who are thought to have had no contact. I have seen the standard answers given to these questions but they don't pass smell test for me. I think it's much more likely there was a more advanced human culture or another species a thousands of years ago that was moving humans around the planet for various purposes. Then one day were gone for whatever reason.

[@justforplaylists]

​@@Bitchslapper316 I'd recommend a podcast called "It's Probably Not Aliens", they talk a lot about those sorts of ideas. But generally, that's selling humans short.

[@Bitchslapper316]

@@justforplaylists I've seen some of them. I'm not saying I believe the crap shown on ancient aliens. However there's never been an acceptable explanation of why humans decided to walk out of a cave tens of thousands of years ago and make up stories of "gods" coming down from the sky. We as modern humans try to apply our own cognitive bias to our ancestors. We see religion from our earliest memories, it's in our schools, on our TV, on the radio and all over the internet. We think believing in religion or a god is normal because in this day and age it is. We apply that same thinking to people thousands of years ago and say "oh it can't be someone actually coming from the sky, it had to be a religion!". I'm also not saying aliens built pyramids, I'm not selling humanity short. I'm saying that all of written history, legends and myths from across the planet from China to India to south America tell us about "gods" coming down from the sky.

[@MirlitronOne]

You've all taken Dr Who too seriously.

[@Jezee213]

Omg, that sounds amazing! I'm going to check it out!

[@docnelson2008]

An excellent discussion of an interesting hypothesis that many dismiss as too speculative despite, as Matt points out, is a valuable exercise for helping us understand so many questions about life on Earth and elsewhere. A marvellous channel.

[@Beya045]

Absolutely phenomenal. Watch all the way through. Thank you for a profound piece.

[@jeffk3746]

This is the proper way to debunk a conspiracy. Don’t strawman the argument or attack the proponents, steelman the argument and actually try to take it seriously, while looking for contradictions that imply falsehood

[@cp37373]

Lol false

[@jeffk3746]

@@cp37373 great argument bud

[@michaelhobbs8082]

How deeply, deeply I wish this is how humanity worked. The political environment in my country is so entirely incompatible with your notion that I think, if we ever achieved the level of rhetoric you imply, it will have completely vanished within our lifetime. The Information Age is giving way to “might makes right” and hypothesis driven science has lost relevance in the public discourse. The adage that “science doesn’t care what you believe” is no longer about truth - but rather a reason to ignore it.

[@oasntet]

It's a useful analysis for other reasons, but it's not a great way to do debunking. The main issue is the imbalance of effort; it takes almost no effort to start a new conspiracy theory, but huge amounts of effort to treat it seriously and do the debunking. And then once you're done debunking, you get lumped in with "them" and are in on the conspiracy.

[@garethdean6382]

The problem is that a solid conspiracy involves the deliberate destruction or hiding of evidence. Any absence of evidence is merely evidence of a successful conspiracy. Only the believers can be trusted and they always find LOTS of stuff.

[@S1nwar]

its really frustrating to think about how hard it is to build a truly functioning timecapsule that is both reachable(and not parked in geostationary orbit), understandable(no language will survive) and mechanically/chemically stable enough

[@Solnoric]

There's an orbital time capsule that won't come down for a few thousand years, so I'd say that most of it is relatively easy to do and the challenge is language, and even then that's not an insurmountable hurdle.

[@ericsaul9306]

That should be relatively easy, you could just write in quartz but if you wanted for this to last for millions of years you should produce millions of this quartz "picture books" and store them through the world

[@greenanubis]

Depends on the time scale your time capsule has to survive. Thousands, easy, sticks and stones will do ya. Millions, you can do it if there is enough of people in civ. Billions, things start to get muddy. Concept of time capsule falls apart. Yea, you can have stuff that can theoretically be stable for trillions of years, but in our universe(practice) you basically have just enough time until your star goes red giant. Until stuff gets recycled on cosmic (time)scale.

[@uclakirk]

We’d have to go all in on the “The Inner Light” strategy and download the experiences of a middle aged man living in a dreary small town straight into the brain of a random alien passing by

[@t.c.bramblett617]

Indeed. It's much more satisfying for me to imagine our existence in the constantly flowing, changing, boiling exchange of matter and energy as a transient game, and to accept that even as we reach out to know more and more while we are aware.

[@s4098429]

The same thought processes and experiments could be used to help find evidence of very brief biogenesis on Mars or Venus. Figuring out the origins of trace amounts of unusual stuff is worthwhile.

[@duskfallmusic]

Ive' been extremey dissociated all night struggling to watch anything -- but apart from playing a game or two, i managed to watch this whole thing, it was JUST calming enough and not super hyped up that I could pay attention - It was really cool, and i'm really grateful that when my brain wants to fold in on itself i got a home on youtube i can poke into for info content :)

[@QoraxAudio]

What do you mean?

[@marcelbruin9151]

​@@QoraxAudiohe was bored

[@Devlinator61116]

I find it funny how the Silurian hypothesis was named after the pre-human race called the Silurians in Doctor Who, which were named after the Silurian period, which ranged from 443.8 to 419.2 million years ago, a time when such a civilization may have hypothetically existed. It's all very recursive, like Pokemon Yellow being based on the Pokemon anime which was based on Pokemon Red and Green.

[@dinoflame9696]

And the Silurian is named after an extinct civilization

[@Crushnaut]

If the Silurian's did exist, they existed before all the worlds major coal beds were laid down, 350-300 MYA.

[@thomasrinschler6783]

While they are named that by a scientist in their first story (and the name sticks), in a later story (concerning their aquatic cousins the Sea Devils), the Doctor says that the time period is incorrect and they should be called "Eocenes"

[@kothar6159]

Funny enough I just got yellow.

[@frankn254]

Red...and Blue.

[@rhysanthony]

This is why I love PBS Spacetime. They’ll cover cutting edge physics topics one day, and then give a fair look at far flung topics like the Silurian hypothesis the next. Fantastic work.

[@ajchapeliere]

all while being clear about what degree of fact vs speculation is going on, too!

[@TylerHimothyOneJr]

I think I prefer Anton Petrov personally, if you havent heard of him you should check his channel out. I will say I did enjoy this video, but tend to disagree with some of their stances in other videos

[@hilohahoma4107]

Yes but they are inherently biased being connected to the most nefarious misinformation paradigms the world has ever seen such as the U.S. Guv which is hiding tons of artifacts proving there WERE non human past civilizations.

[@blink182bfsftw]

​@@TylerHimothyOneJr2wa%@❤❤❤

[@hofmannwaves1525]

LOL they're the most establishment-dogma show out there they hate the idea of aliens it calls anything non-material woo-woo they're the image of obnoxious close-minded modern scientists

[@zbighugh9193]

Ozymandias BY PERCY BYSSHE SHELLEY I met a traveller from an antique land, Who said--"Two vast and trunkless legs of stone Stand in the desert....Near them, on the sand, Half sunk a shattered visage lies, whose frown, And wrinkled lip, and sneer of cold command, Tell that its sculptor well those passions read Which yet survive, stamped on these lifeless things, The hand that mocked them, and the heart that fed; And on the pedestal, these words appear: My name is Ozymandias, King of Kings; Look on my Works, ye Mighty, and despair! Nothing beside remains. Round the decay Of that colossal Wreck, boundless and bare The lone and level sands stretch far away."

[@keithtinkler4073]

Thank you that - very appropriate.

[@glock112983]

This was awesome. This answered a lot of serious questions I had about this idea.

[@cherokeegabel2397]

I think it would be safe to say that if a second "advanced civilization" did emerge, they would immediately know about our existence as soon as they went to the moon... Of course this considers our future proposals of lunar construction and expectancy of human existence...

[@RicardoSavino]

Yes, but what are the odds of they finding something so small on a huge place like the moon? Maybe after we get to the poles, but if we kill ourselves before that, it would be another story.

[@Dennodq]

They would probably think it was aliens.

[@jpuroila]

Depends on how soon they emerged. Also, human remains on moon are (at least currently) limited and easy to miss.

[@obscurity3027]

The surface of the moon is pretty damn big. It’s not a certainty that a future civilization would explore the same small area as the one on which we landed.

[@apokatastasian2831]

also a few meteor strikes in the right places would scatter our footprints and bury our landers and that'd be that

[@brutussmithicus]

I have a Douglas Adams inspired variation on the Silurian Hypothesis. The Dolphins land dwelling ancestors once built a great civilisation, mastering the wheel, cities, post office towers, wars, etc. But the more they developed this magnificent civilisation, the more they realised that they could only de-stress from their high flying careers by mucking about in the water having a good time. Then came the most important moment in their social evolution - they realised that all of these achievements were a pointless distraction from what they actually enjoyed! So they genetically engineered themselves to become fully aquatic, dismantled & cleaned up all of their cities (to avoid giving any future advanced species bad ideas) and retired to the sea, where they have been mucking about and having a good time ever since. The only thing which depresses them is watching humans make the same mistakes, which is why they try to make friends with us & encourage us enjoy mucking about in the sea whenever possible. Whilst completely unsupported by evidence, this hypothesis is now ready for peer review :D 😍

[@gaeroot]

They must not have invented WiFi. No way anyone is giving that up.

[@brutussmithicus]

@@gaeroot Hmmmm, debatable. When I think about the amount of stress I suffer from low battery alerts & listening to ignorant morons spout pseudoscientific BS with supreme confidence, I often want to throw myself into the sea 😕

[@kennethmartin1300]

@@brutussmithicusBut, present company excepted, of course!🤔

[@jamesc8843]

What’s that cartoon that makes the dolphins god like lol

[@brutussmithicus]

@@jamesc8843 Dunno, but worshiping dolphins sounds like a much better idea than worshiping any of the 10000 deranged gods that humanity has invented so far. There is good evidence that dolphins actually exist 😀🐬

[@pastorpresent1]

I think the one who should take a bow here is the one who wrote the script for this video. Very well done! I was somewhat convinced that there had been previous ancient civilizations. But you dealt with all the issues I could think of in a way that was compelling.

[@schfiftyfive9680]

"LIZZID PEEPOL" -Hecklefish

[@cultiv8599]

R u done? -hooman

[@clays1507]

Exactly

[@psantochi]

This whole episode sounds like a bar conversation after a scientific conference. A lot of fun!

[@pavelborisov515]

But without a hangover and burning bottom

[@petergaskin1811]

Sounds like the sort of conversations I have with the World at large after the second bottle of Burgundy.

[@Benson_aka_devils_advocate_88]

"Back of the napkin" equations comes to mind. But this topic has always fascinated me. The chance of a civilization reaching out level of ability when it comes to leaving undeniable signs of its existence is incredibly small. However, a species that develops complex social structures and the basic ability to create shelter, and even a simple mastery of making fire, would be so difficult to detect after a few million years, let alone 100 million. It's incredibly egocentric to think we are the first "intelligent" species. After all octopuses have been around in some form or another far longer than vertebrates have. And they clearly show it doesn't take upright posture with hands and fingers to be able to solve complex problems that require complex problem solving skills. But we have yet to find anything that shows a technical advancement at our level at any time in the last half billion years, and not for a lack of trying either. So, intelligent species is highly likely. Complex social structure is probable. But no, nothing at our level has shown up in the record, _that we know of._

[@billkallas1762]

After everyone having three or four drinks.

[@juliane__]

Except these are only wild wdreams without scientic work of a geologist behind.

[@chaunceyfeatherstone6209]

Stephen Baxter's book 'Evolution' has a chapter exploring this hypothesis. It dispenses with the "advanced" civilization part, which, to me anyway, presents the much more intriguing notion of simply intelligent civilizations before us. If the pyramids aren't going to be here 200 million years from now, what hope would there be for a fire-sharpened stick from 200 million years past?

[@nahCmeR]

Well the pyramids would last exceptionally longer then a fire sharpened stick so I'd say about 0. Really not the best example to use when comparing to the pyramids, I get what you're going for.. but that just ain't it chief

[@razzleyaheard3204]

We have no reason to believe it without evidence in its favor which there is none.

[@Tamamo-no-Bae]

@@razzleyaheard3204 And that is the problem. How would we get evidence of such when 99.9% of all life is erased? The fossils we have are from EXCEPTIONAL cases. If we time travelled back to the cretaceous forexample, we'd see countless species not in the fossil record at all.

[@Alex-ff1mk]

@@nahCmeRyou most definelty didnt get what he was saying if you think that wasnt a good comparison

[@nahCmeR]

@@Alex-ff1mk sarcasm must not be something you're familiar with is it? You don't have to answer you've already made that clear.

[@davidcashin1894]

One thing I love about these videos is that they do not gloss over the hypothetical nature of the question and that they rationally frame that we are forming hypotheses to be tested or in the case of geology searched for and sampled.

[@danm3570]

fun to think about, thanks for going to effort to analyze all this properly 👍

[@senatorchinchilla5389]

I love theories like this because they really explore the vastness of time and space.

[@RATKINGPLUG]

Hypothesis

[@MossyMozart]

@@RATKINGPLUG - Speculation.

[@howardhughes7596]

Theories have evidence that support them, hypothesis do not.

[@SPREAD-THEM]

​@@MossyMozart constipation

[@cyberpleb2472]

@@howardhughes7596 *hypotheses* do not.

[@earthknight60]

For anyone interested in this sort of question the 2008 book *The Earth After Us: What Legacy Will Humans Leave in the Rocks?* by Jan Zalasiewicz is an excellent read. It looks at what the remains of our own civilization will look like over time up to around 100 million years in the future.

[@Dr.Kay_R]

Thanks. I was interested 😅

[@juliane__]

3:06 6:28 No, continental crust is not recycled through plate tectonics. Only oceanic crust is. There is scratching at the boundaries and part subduction of islands, but less than new land mass is produced. Sediments are recycled when being trapped in subduction zones, but as a rule of thumb, these are from mountains. Large continental basins are more or less stable. They stay and accumulate over time. Maybe the early very small landmasses were drawn down, but that is speculation. 6:50 No, we disturbed the earth surface by kilometers depth and wide simultaniously. This will stick out in the the stratigraphic record like a lighthouse. With all machinery 100-1.000t in weight still insitu. Future civilisations will certainly find this simply by observing the magnetic distortion or change in electric conductivity. No future tech, we routinely find deposits in this way. 7:35 No, if they have build roads and rail like we do, we would have find them in the stratigraphy for certain. You can look at river deposits from 100s million of years ago and you can clearly see the geometry with little distortion. As i said large continental basins tend to stay. The stratigraphy down 12 kilometers can be relatively undisturbed. Maybe you guys should stick to astronomy. We are so ubiquitous around the globe, we are one of the defining species of our stratigraphy. Our bones, you plastics, our radioactivity spread, our concrete, iron and steel everywhere and in megastructures, our unprecedent change of the atmosphere and maybe also unprecedent reverse of atmosphere composition. Nothing like this had been found but it would be found for certain. Clearly no one involved asked a geologist. This is 1. semester stuff.

[@vycos-zen]

thank you for the most succinct and informative explanation on this subject, i ever heard. i do see it different, learning about the effects of deterioration, and the eve changing nature of the earths crust. i think we should just get our own stuff together, and not worry too much about the past. :)

[@VRnamek]

if there was such civilisation, maybe our best bet would be to look for artifacts they may have left in pretty stationary environments, like in moons without much geological activity or Lagrange points... they may just be out there, waiting to be found. And indeed as we search for them we ourselves may leave a trail for the next arising curious civilization...

[@georgelionon9050]

Lagrange points are not that stable, they are mostly "saddle" gravity wells or "orbits".. on the long run stuff will fly out (otherwise every body would have moons in the L points)

[@josephdocis1488]

@@georgelionon9050 L4 and L5 are stable, which is why there are groups of asteroids at Jupiter's L4 and L5 with the Sun, called trojans.

[@Somerandom1922]

​@@josephdocis1488however, those orbits aren't that useful outside of their stability. One place to look would be geostationary orbit. It's far enough from earth that orbits can last hilariously long before decaying, and unlike some geosynchronous orbits, there isn't an annoying interaction with the moon that causes it to rapidly decay. However, these would still be small satellites 35,000km away that, if they're millions of years old, may very well have been destroyed by a interplanetary pebble.

[@mattmaas5790]

Well the senate passed a bill that literally talked about declassifying non-human intelligences artifacts and then Republicans just totally gutted it. It's big news in the ufo community and does have lots of specific examples of things to declassify...

[@monad_tcp]

just find the Tacitus

[@mayoite160]

this is the best explanation of the silurian hypothesis i've seen so far, not to mention the most comprehensive exploration of its implications, something sorely lacking from the other videos

[@theark1400]

@@iridium8341doesn’t elaborate 💀

[@Ezekiel903]

agree, but we are missing 100 million years in geological layer, and he assumes that an earlier civilization used the same technology as us, atomic energy, earth fertilizer, oil based industry et cetera, which is a big mistake.

[@paulonius42]

​@@Ezekiel903we have to look for that with which we are already familiar. He doesn't assume anything. He explains how our kinds of technology and energy would leave markers for future generations, because we are the only example of technology and energy use to go by. What exactly do you suggest we should be looking for? Please tell me how to look for an unknown technology we have never conceived.

[@Ezekiel903]

@@paulonius42 massiv build buildings, like the new one found in Siberia, over 8000 years old!

[@paulonius42]

@Ezekiel903 There was no massive building found in Siberia. The 8000-year-old fortress there was a very modest construction. We have other much larger fortresses dating back 5000 years. An 8000-year-old fortress is evidence of our civilization's ancestors 8000 years ago, not even remotely something connected to a previous civilization millions of years ago. Also, the video explained why buildings will be far less likely to last as long as the kinds of evidence he cites in the video. Perhaps you should watch the entire video before commenting next time.

[@jozjonlin3170]

Glad you mentioned the PETM. That era is frighteningly similar to what we see right now. I doubt we'll ever have the evidence to say for sure, but it's entirely possible an advanced civilization lived during the PETM. Possible? Yes. Likely? No.

[@ctuna2011]

"Distant Origin" is the 65th episode of Star Trek: Voyager, the 23rd episode of the third season. Voyager encounters an alien race, but runs afoul of their principles. The Voth are humanoid lizards, and the plot revolves around one particular scientist who has taken an interest in studying Voth origins. They were from Earth and it was hearasey for them to acknowledge the Intelligent monkeys from the same place. Also touched on in Dr Who.

[@r1nger81]

Matt is a fantastic narrator. He's certainly qualified for physics related stuff, but he would make a great documentary narrator on any topic.

[@GenericInternetter]

Simon Whistler

[@r1nger81]

@GenericInternetter Yeah. I dig fact boy too. Great presenter...no shortage of KZbin channels 😁

[@ArawnOfAnnwn]

@@GenericInternetter He has enough channels. Don't spread him even wider!

[@falconeagle3655]

he IS a physicist

[@Jezee213]

he really is great.

[@noanyobiseniss7462]

Any civilization that follows us will find our footprint on the moon if nothing else.

[@norneva775]

Nah they’re will still be some McDonald’s burgers in perfect condition 2,000 years from now

[@noblenormie1179]

Smartest american:

[@michaelyaziji]

Fun. Thanks. 1. Did we just focus on the last 1/2 billion years? 2. I understand Occam’s razor, impossibilities of proving a negative, etc., yet I’m not sure why we assume it is an extraordinary claim (therefore requiring extraordinary proof). Couldn’t we frame it as a default assumption, since all of our experiences of 500m-year-earth timeframes for which we have data has led to technological civilization? Thoughts welcome?!? 😊

[@coolsa]

I've done some thinking about this, when looking back at some historical mass extinction events. The Permian-Triassic extinction event roughly 250 MYA was one that really stood out to me, even though it everything I'll mention can be solidly explained by the aforementioned catastrophic volcanic-fuel interactions. The P-T was one of the few known mass extinctions of insects, which we are also doing. It has some evidence of ozone layer depletion, which we narrowly avoided with CFC's. It has evidence of a large dying of marine life including coral, which is an issue that our actions with ocean-acidification is amplifying. Not sure how volcanism could cause the insect extinctions, but there are some hypothesis that the burning of coal and high-temperature interactions could have created some highly-reactive ozone-consuming chemicals. Volcanism could have also generally increased the CO2 in the atmosphere, leading to increased acidity of the oceans, and then wrecking coral life. Also, a little strange how during this time the Lystrosaurus made up such a large portion of living creatures and left behind so many fossils. Haven't really gone further, but its a very interesting thought experiment! Something for a team up of interdisciplinary researchers to look at... Edit: Forgot to mention the C12 and C13 ratio! Those changed radically due to the mass-burning of organics, which could have been caused by the Siberian Traps volcanism, or by some species of coal-burning creatures.

[@whifflingtove]

Are you suggesting Lystrosaurus could've been domesticated? Why would it be strange for it to be just a very successful grazer?

[@bpz8175]

The mass extinction of insects in the P-T event isn't sudden though (unlike today). Given that the P-T is also the largest mass extinction event on record, it would be expected that insects be affected more strongly just like other life. On the other hand, we are arguably causing insects to go extinct before any other group of animals due to our land and pesticide use.

[@coolsa]

@@whifflingtove They could have been the most successful grazer of all time, and somehow avoided predation (until their extinction), or just happened to live in a way that favoured fossilization (like living by flood plains). Some food for thought though, humanity and our domesticated animals make up around 95% of current land-mammals lifeforms, while Lystrosaurus makes up 90% of the fossils found from the PT boundary. Thinking about it like a science-fiction enthusiast, perhaps they were a domestic species of a specific obligate carnivorous species. Perhaps they were themselves the tool-users, and progressed much much slower than we did in technology, getting "stuck" in some places, and not innovating themselves out of some Great Filters. Who knows what other sapient species would do or how they would behave, that's for scifi authors to speculate, with emphasis on the fiction.

[@coolsa]

@@bpz8175 I mean, there is a 15 million year gap in insect fossil record between the late Permian and early Triassic, with a major shift in dominant species occurring somewhere in this time, so its hard to pin down how long the insect extinction took. Though, the source for that is a paper is dated to 1993, and I really hope that further research and discoveries have happened in the time since, since my main source is Wikipedia citations. A quick google search shows a 2022 paper published in Frontiers claimed that 1/3 of insects went extinct at the PT boundary, which pretty similar to the 10%-40% of insects currently endangered in our Anthropocene era. This paper also specifies these extinctions occurred after a long decline from the middle-Permian onward, so its super unlikely that this was actually caused by any sapient species, but its still fun to speculate!

[@ericsaul9306]

​​@@coolsamore food for the thought! Humans and our pets and livestock will be fossilized by the billions so we will appear quite ubiquitous on the fossil record, the reason for this it's that one of the requisites for fossilization that makes it such a rare occurrence is that the body needs to be buried soon after death, preferably before decaying and before predation in an environment conducive to fossilization and protected from crushing or again predation, this is basically what we have done for thousands of years through burials, it could be the case that Lystrosaurus is so ubiquitous because it was ritually buried too.... Then again probably not.

[@JoePatterson]

Imagine how interesting it would be to find the remnants of a billion year old lunar lander.

[@casinodelonge]

Yes, space artefacts are something he didnt touch on.

[@tukkajumala]

The Moon is hit by around a hundred detectable asteroids every day. Within a billion years the Moon is hit by tens of trillions of asteroids, traveling tens of thousands of km/h. A single nearby impact would annihilate the rover, sending it into space in tiny specks.

[@KevinWarburton-tv2iy]

Yes, but maybe, just maybe there some ancient underground bases/mines, artefacts, ruins on Mars & the Moon. We might find our evidence for other life from elsewhere or elsewhen out there rather than here on Earth.

[@librapondo_]

Question to the maker of this video: I really enjoyed it, if an advanced civilisation launched a satellite, would it have survived to present times in the atmosphere of space?

[@robertabblebaum7813]

Potentially. Most satellites are going to re-enter earth's atmosphere and be destroyed on re-entry. The few that might be thrown out of it's orbit would just be one grain of sand on a beach. There'd be no way of finding it other than by pure dumb luck.

[@udishomer5852]

Great video! Keep up the good work

[@IsaacKuo]

I love the Doctor Who origin of "the Silurian hypothesis" name, because it's an example of Doctor Who actually being scientifically valid. The "Silurians" aren't called "Silurians" by the humans because that's the age they're actually from. Instead, humans call them "Silurians" because that's the geological layer where they found their underground hibernation base. It makes sense that this is a lot deeper than the geological era they're actually from, because they were creating an underground hibernation base from the start.

[@HassanGaba1]

Excellent. This was a really thought provoking video and I must commend the team behind spacetime for not considering this topic off limits, because I trust that with Matt behind the show even a speculative topic like the silurian hypothesis will get the spacetime treatment that it deserves.

[@RobleViejo]

Hijacking the Top Comment to ask a simple question : Why is there so much Xenon 129 in Mars?

[@mattp3518]

​@@RobleViejothat's a very good question that nobody seems to have an answer for

[@petergaskin1811]

Not strictly a hypothesis, I think that this should be filed under "Brainfarts".

[@goobyboxxton8526]

@@RobleViejo Saw this comment and felt the urge to contribute. This video was interesting and a partial explanation of this is addressed at 15:14 when nearby supernovae are mentioned as a possible source of fissile material. Interestingly the half-life of some of these materials and the distances involved would make it impossible to travel such distances and be deposited on planets in our solar system. A controversial alternative hypothesis is solar micronova events. Such events could have also restarted biological development on our own planet. So was it an advanced civilization that wiped itself out from nuclear war, or was it a solar micronova event that sterilized life in our solar system? Or even more far out, was a solar micronova event triggered by an advanced technology as a doomsday weapon or technical failure? The possibilities are only limited by our imagination. Happy hunting all!

[@beardmonster8051]

I just want to point out that even if life did exist prior to sterilizing asteroid bombardment that wouldn't necessarily mean that abiogenesis occurred twice on Earth. Panspermia would be another possible explanation, and in this case we wouldn't even have to go far to find a possible origin for that second occurrence of life. It could have originated on Earth, been launched into space by an impact and then returned via a new impact after conditions once again could support life.

[@rwschumm]

Yes, this is becoming a fairly common thought. Many even think that prior earth residents are actually living underground, or under the ocean somewhere.

[@user-ro5tn3zt1d]

Another amazing video that really makes me think about, well, everything 😆 i'm a 13 y old girl and literally one of my most favourite things is coming home from school and curling up in bed with my cat and watching this channel for literally hours on end till my parents get home from work lol. I've been watching you for a few months now and I'm not lying when I say I've learnt more from this channel than I have in my physics class 😂

[@Ggdivhjkjl]

Have you thought about uploading a video of your cat? 🐱

[@user-ro5tn3zt1d]

@@Ggdivhjkjl I have but my dad said I'm too young to be uploading stuff. Maybe when I'm older I will. For now I'm using the internet to learn as much as I can BC I think I want to study astrophysics when I'm in college 😀

[@Justmint939]

@@user-ro5tn3zt1dyour dad's totally right. Too many creeps out there. Good luck with astrophysics!

[@Dover939]

@@user-ro5tn3zt1d You should listen to your dad. Tons of weirdos especially on youtube. I hope you do well in college, I'm in college now myself

[@ditalotl]

Hi, I am glad you have an interest in these topics and wish you all the best and a lot of luck in your future goals!!! :) But, please be careful of weirdos on the internet! You already posted way to much info, such as your age /gender, as well as the fact that you're alone at home after school (telling you have a cat, can also give someone an impression about your personality, but also narrow you down from a group of people). I am sorry to say this, but sadly, all these info are just gold for creeps lurking around, (online, but also offline...meaning in the real world!). Don't want to scare you either, but I would really advise you to delete this comment :/ You can write another one, if you like, but please keep the info you give about yourself (anywhere on the internet...but also sometimes in real life) to a minimum! Again, wish you the best in the future, and above all...stay safe :) p.s. DON'T EVER send or upload anything online, without your parents consent (and also, only if you feel okay with that!), no matter WHO asks you, okay! Please!!! Even if the requests may sound like they're harmless, like the one from one of the dudes here asking you for cat videos, or whatever! Sorry again if I am scarring you, but better a bit scarred now than very sorry later! Bye 🖐

[@barkasz6066]

Nothing like a bit of existential dread in the morning. This puts the 9 to 5 daily grind in perspective.

[@MSIContent]

Excellent and thought provoking. Nice work.

[@robbob3052]

Stumbled onto this channel like 2 weeks ago. Very happy I did.

[@timurphy8888]

I’m certainly intrigued by the concept of an ancient industrial civilization, I think it’s much more likely (and thus more intriguing) to think of an ancient civilization that wasn’t advanced technologically. Did creatures exist that drew on caves walls that have long ago crept below earth’s surface? Can we ever know?

[@TheGyuuula]

The genes and proteins allowing highly intelligent species to emerge just evolved rescently. Even chimps must acquire a few extra mutations to be able to get the level of humans. Anything living before and during the mesozoic could hardly beat a chicken in intelligence.

[@MossyMozart]

@timurphy8888 - Sounds like that so-called "hollow earth" fantasy.

[@TheGyuuula]

I'm pretty sure I had a commented on this, but it's not visible for some reason.

[@AiNaKa]

@@MossyMozart i think they meant the caves crept below the earth's surface as in subduction

[@FabsHF]

Not only drew on caves.. If there was an Inca or Mayan kind of civilization (non industrial, but with fire, tools, writing, mining) 5 million years ago.. And they lived in a now flooded land.. Could we ever find out?

[@Ganjor420]

I just realized, the sadest solution for the Drake Equation would be, if it turns out the limiting factor why we don't see life everywhere is the duration a civilization survives, and not how hard it is to get there in the first place.

[@oasntet]

The Great Filter is no joke.

[@8584zender]

Sagan pointed this out in the original Cosmos. He ran the (at the time) best guesstimates for the variables in the Drake equation. It all came down to the life expectancy of a technological civilization. If that number was 100 years (from invention of radio to extinction) then the number of radio communicating civilizations in the Milky Way is 1. Just us.

[@icekingsbattlefield9805]

The dark forest theory could be the answer

[@danielash1704]

Amazing thing about the material of everything when you consider that vibrations are exactly the same thing

[@astyanax905]

It's not quite as insane as I once would have thought. video is bang on correct.

[@capt.picard445]

As someone who grew up watching a lot of fascinating documentaries on Discovery channel only to see it go down to become the conspiracy theory sh*thole it is now, I started watching this video thinking ‘No PBS SpaceTime, please don’t’, and ended it thinking ‘Thanks mate, thanks for a detailed explanation’. Thanks for taking on a risky topic and explaining it without bias.

[@mkhanman12345]

Can you discuss what the vid was about

[@MrNuki42]

Just a little reminder: The whole human experience is biased, because we can only perceive the universe from our perspective. We might be "3D Creaters" living in an 11-Dimensional Universe. The key is to question everything and stay true to the scientific principles which lead to a profound understanding of some laws of the universe so far.

[@sidereus8654]

They still have to work that algorithm. Even the thumbnails aren't really representative of the quality of content that is contained within the videos, but that is what people click on so that's what they have to do. The titles are the same way - wording it like they do engages a much wider audience that otherwise might not end up seeing this channel. The people who already come just for the channel are going to see it anyways, a clickbait-y title and thumbnail aren't going to affect that but will draw in thousands or millions of other viewers.

[@oskarskalski2982]

PBS space time have long ago surpassed any documentaries on either discovery or NG. Neither of them can equate with pbsst in quality of the physics related material.

[@ProYada]

@@MrNuki42 Theories are fine. Theories without evidence disguised as fact are not.

[@shadowmil]

I think this type of question and this type of thinking is very important, regardless if we find ancient civilizations or not. This search answers important questions about how we're affecting the environment we live in today.

[@tiffanymarie9750]

@irdium8341 I hear there are a few nukes lying around that would make a big splash

[@wally7856]

We are not affecting it in any way given enough time. 2 billion years from now tectonic plate movements will erase any evidence of our existence.

[@imveryangryitsnotbutter]

@@tiffanymarie9750 Nukes: the "forbidden technology of the Ancients" of the future!

[@dcptiv]

tectonic plate movement devours everything on the surface over time.

[@davydatwood3158]

"We're on track to get at least one [example of an extinct civilisation]" was exactly the humour I needed this morning. :)

[@jajssblue]

This is why it is important that we scatter as much long lived synthetic radionuclides across the world. Got to leave our mark! /s

[@georgelionon9050]

If we wanted to tell future civ to go ### themselves, how would we do that? And they need to understand it too.

[@xaviertorrence2559]

New golden record but the human figures are flipping the bird

[@icedbear]

Have you heard of Crawford Lake? Currently the best location that records our impact. Also called the Anthropocene lake.

[@russellzauner]

Don't make me go up there with an immersion blender and mix the layers!

[@TJ52359]

I think I just saw a Video from Eons a week or so back...

[@dewaard3301]

Did they not recently do a video on this exact lake?

[@henrycarpenter5733]

Good video, apart from one small hiccup. The narrator implies that the anthropocene consists of the last 10,000 years of relatively static climate, suitable for agriculture. It's more accurate to refer to that as the Holocene. The anthropocene is then just defined as an event beginning with either the industrial revolution, or the atomic bomb tests, depending on your point of view.

[@wtflolomg]

I always felt like the Drake equation ignores the idea that civilizations will develop in different windows, and secondly, that the time period within such a civilization where they are "noisy" with RF to be detectable would also be even more fractional. A civilization that is more advanced than us might develop tech that can communicate across interstellar distances without "broadcasting" energy (it's noisy - attracting potential threats - and inefficient)

[@billfrehe6620]

THIS is exactly how you address extraordinary claims like the Silurian Hypothesis. Such claims require incredible standards of evidence. Scientists can take them seriously, there's nothing wrong with that so long as we recognize that the standard of proof is extreme.

[@kh9242]

All that is needed is sufficient evidence it need not be extraordinary

[@Titere05]

It's very complicated to prove, but also to disprove

[@billfrehe6620]

@@kh9242 Wrong. This is why idiot pseudo-scientists get mocked, they make outrageous claims and put up underwhelming evidence to match the claim. The evidence must match the claim. In the present case, there's zero evidence.

[@billfrehe6620]

@@kh9242 Wrong. This is why idiot pseudo-scientists get mocked, they make outrageous claims and put up underwhelming evidence to match the claim. The evidence must match the claim. In the present case, there's zero evidence.

[@vibovitold]

it's essentially a thought experiment which can serve as a starting point for asking actual (interesting and relevant) questions. a thought experiment doesn't have to be plausible in and of itself, in terms of realism of its assumptions.

[@PhilW222]

Many years ago I remember hearing about a dinosaur species (sorry I can’t remember which) that had developed a bigger brain in the later Cretaceous, and the commentator said that had it continued to evolve, it might have been almost as intelligent as humans, and my immediate thought was that it had millions of years head start on the mammals so it would have been MORE intelligent than us. This is a nice overview of what markers might be left, an exciting albeit unproven hypothesis.

[@Shard18]

Mammals actually slightly predate Dinosaurs. Also imagen in the future a new race finds like Babboons or something and r like" if they only had a few million more years they could have been people to." Compleatly unaware we existed. With a hand full of remains artifacts that there academics dismiss as hoxes like we do with stuff like the Critacius hammer

[@jamisojo]

Sounds like a fictional story to get views rather than anything factual.

[@MJG206]

Hadrosaur.

[@Krezmick]

Think how smart some modern bird brains are. I would guess one of the bipedal dinos is a good start.

[@KevinWarburton-tv2iy]

Troodons?

[@ToTheGreatWideOpen]

The Great Wide Open People have FUN FUN with the idea that.. *In the future we'll be revisited by an ancient alien civilization, - Relaxation is needed.

[@Paul.atherton]

Imagine the stuff that is just under water... off the land bridges that are very recently under water. Imagine what civilizations have been lost to time itself

[@JMurph2015]

I think the line of radioisotopes will be pretty unmistakable for a long time into the future. We can't even properly make new steel (easily at least) that doesn't have some miniscule amount of radiation background now. I've read that steel from before the atomic era has become its own market for applications that need very low background radiation levels.

[@DalHrusk]

Do you know how long it takes for those steel contaminating isotopes to decay? Will it be issue after few milions of years?

[@TJ52359]

maybe i'm being difficult... but isn't the Radiation level of Pre-1945 Steel only considered "Low Level" Because Post 1945 is "HighER" and we know what we did in 1945.... If Earth shakes her etch-a-sketch... and the Dog-People rise up in a Billion Years as the 3rd Civilization ; our post WWII numbers will be the only Baseline they know ... and those levels will Either Hinder their ability to do what ever it is that we think we need 'low levels' for; or they will find their own work arounds to it (that we don't consider/solve, because we can still find it however scarce

[@JorgetePanete]

that* its*

[@kennethferland5579]

The problem is that is a test for nuclear technology (specificcally its misuse), not a general test of technological civilization.

[@nigh7swimming]

What if Snowball Earth was simply a nice ski resort for aliens but went out of fashion?

[@Lomogrammaton]

It’s more like a zoo for aliens. So when they come they are just doing a typical trip to the zoo.

[@ArmstrongandTumbler]

I've been talking this theory for so long now, I'm happy someone is covering it in fine detail. There is such a possible chance humans are not the first Earthlings!

[@williamthornton5856]

Something that Mark mentioned, was looking in the past and seeing if there were any periods where worldwide temperatures rose in centuries (like we are doing, anthropogenically with industrial processes) versus taking many thousands of years from most known natural events... Well yes. There have been periods where temperatures actually rose even a bit faster than present times. Human caused climate change is happening, and it does deserve attention to reduce it. World wide temperatures due to human Anthropogenic causes have warmed the world temperature by almost 0.95 deg C, since 1900, and rough estimates are that somewhere between 70 and 90 % of that is human caused. The speed of the rise is very fast compared to most known natural causes. However, 125,000 years ago (during the Sangamon Interglacial) it was 3 deg C warmer than now, AND (this is the important part) it warmed slightly faster then, than the last 100 years from 1920 to 2020 (for 3,000 years) with sea level rising about a foot every 100 years. In the last 100 years sea level has risen about 6 to 8 inches. 125, 000 years ago sea level was about 9 meters higher than today. Think of all the coastal cities, that would exist 125,000 years later that are located where shallow ocean was "then". The climate flattened out temperature wise from 126, 000 years ago to about 119,000 years ago, then it cooled down again over several thousand more years. Eventually another ice age hit, sea levels fell to well below what they are now, (by ten's of meters) and the last ice age ended about 18,000 to 14,000 years ago as it warmed back up. Sea levels rose to near present levels by 10,000 years ago. Human greenhouse gases are warming the climate today about 70 % as fast as it warmed starting 129,000 years ago. Problem is, today we DO NOT know (with certainty) the factors that caused the climate from 129,000, years ago to 126, 000 years ago to warm “soo” quickly. It was something other than rising CO 2 levels. There were no human industrial revolution factors then. It is it is hard to find evidence after125,000 years. There is evidence of sudden shifting ocean currents at that time, and widespread undersea volcanic activity (some evidence from paleomagnetic correlation with known Pole reversals), that could have ejected huge amounts of water vapor into the Stratopause, (which also happened recently in 2022 with the one Tonga Undersea eruption,) but we do not know “with certainty” what caused such rapid warming starting about 129,000 years ago. Though large scale volcanic activity (much more than in the 20th Century, or this one Tonga undersea eruption) is a possible contender, for such rapid climate warming, especially undersea eruptions. In fact, large scale undersea eruptions are one of the few natural events that could cause global warming as fast as humans have been doing. We do not have enough sampling to prove it at this point, regarding the rapid temperature rise leading to the Sangamon Interglacial where is was world wide, significantly warmer than today. However, 125,000 years ago is too recent for a large technological civilization, as more evidence would be present. even natural caused rapid warming comparable to present day human industrialization has happened in the past. However, if there was a tech civilization a half billion years ago, virtually all evidence including any climate change from such a civilization, would be virtually impossible to prove today. Interesting to ponder though.

[@salmonesque]

Incredible writing and great presentation. I love this channel.

[@_MAXrevs_]

That ..."Spacetime" finishing sequence at the end of video has always enthralled me❤

[@jimmyzhao2673]

Try ending all your conversations like that for fun. 😀

[@NexuJin]

@@jimmyzhao2673 won't have many conversations after doing that too many times 😅

[@billg.7909]

I would never watch a video with this title, except when produced by PBS Space Time. Great work again Matt and all.

[@SouthPoleAntarctica]

imagine the joy of future scientists when they see the levels of natural C12 being finally released from its tombs of carboniferous era following the impact of polymer asteroid distributing worldwide thin layer of deposits not unlike the K-T, getting the planet back on track with the climate suitable for growth of corals and other radiata

[@stuffandnonsense8528]

Even at 3.8b we can have a good guess that abiogenisis is extremely quick and common. The thing which clearly takes a long time (or is extremely rare) is complex life.

[@Welverin]

It never ceases to amaze me that the Drake Equation, an equation made up entirely of variables, gets any play. It’s just making up the probability of other life in the universe with extra steps, while giving it an air of respectability so people are fooled into thinking you’re not just making it all up.

[@chrisdonovan8795]

I thought Drake was just a singer. Huh. The more you know. 😂

[@garethdean6382]

It's organized ignorance,and it's very useful when you make up 'reasonable' numbers to argue your case. It gets play because it's a useful tool, if only for the person arguing.

[@fbsfgr]

Make a better guess.

[@KevinWarburton-tv2iy]

The point is that the variables are markers, placeholders ...a framework superstructure in which we strive to fill the gaps with facts within each Variable Box. It gives us an Endo-Skeleton on which to adhere "the Flesh of Knowledge" as we learn more.

[@Welverin]

@@KevinWarburton-tv2iy Nice try, but that's nothing but a bunch of flowery language trying to obfuscate reality: no one actually treats it that way much less makes it clear that's all it is.

[@mikebmcl]

Sort of related, I occasionally wonder whether or not we would actually pick up any of our signals, TV, radio, etc., if we had our SETI setup and other tools in a nearby star system.

[@kirkhamandy]

Wonder no more, you can Google this answer. Just search for "SETI link budget". A "link budget" is the term used by communications engineers to figure out the power their transmitters need to be received by a receiver of a certain sensitivity (with potential noise sources thrown in on the link path). You find a few sites with calculators that explain this in more detail and allow you to find various distances based on signal source and strength. I warn you though, when you understand the link budget it starts to get depressing, and you'll wonder why we're even bothering with a SETI project.

[@Ser_Loyne_duBeoufe]

Excellent question.

[@imagseer]

@@Ser_Loyne_duBeoufe Yes, and even the possibility that any alien replies might be replies to 'Silurian' messages that they intercepted.

[@mattmaas5790]

Nope they become fuzzy right away basically

[@magma2050]

SETI automatically discounts any human signals from being evidence of intelligent life 😁

[@raffyc66]

I imagine Earth's crust as a lava pit, where you see subduction of the hardened crust under another layer... but in extremely slow speed. If you can visualize that, I think you can imagine the rest of my theory. I think it is possible in the vastness of time, to have all evidence of previous civilizations totally, and naturally wiped out, and in fact recycled. The propensity of civilizations to inhabit coastal areas makes it even more credible as a theory, as the glaciations raise and lower the water column, possibly scraping clean any coastal or maritime structures. This is all so fascinating to a simple, regular minded guy like me.

[@briceonyoutube7215]

If you look in the ground for traces of our passage you might not find it but if you look in space, in our orbit, our industrial civilization left quite a bit of evidences!

[@tiffanymarie9750]

I think it's likely we're the first industrial civilization, but "technological" to me covers basic agriculture, hunting tools, and food processing. Given that, it's only somewhat unlikely to have happened in our past. Those kinds of civilizations would leave basically no trace in the fossil record after 500my or so. Edit: maybe watch the video before responding, just a thought.

[@chienforcer]

If there was a civilization that was technologically at or above our current level of technology on Earth, then it is possible their technology could have been biodegradable and not detectable by us at this point.

[@seanparker7415]

I haven't watched the video yet, but if there were a previous industrial civilisation, we would see deposits of iron on the earth's surface: we wouldn't have to dig deeply for iron ore that was geologically deposited. That is, whilst previous cities might have disappeared the elements that supported such civilisations (copper, tin and iron) would remain as superficial deposits that had been previously mined.

[@ericsaul9306]

​@@seanparker7415the problem with that comes from just tectonic plate subduction, as the video stated, after 500 million years no such deposits would be left, they just would be recycled and mixed around only to be thrown again by volcanoes, basically if it wasn't an industrialized society they would be invisible to us

[@rog2224]

@@seanparker7415 "we wouldn't have to dig deeply for iron ore that was geologically deposited" Why?

[@tentacledhorror]

No, there would be a lot evidence. You can't have a civilization without a lot of stuff left behind. Agriculture leaves a lot if evidence behind.

[@user-rm2qj2jh4l]

This is so cool! I love that PBS Spacetime is exploring incredibly unlikely hypothesis like this, and what their implications could be, without sensationalizing them at all, and being real about the actual likelihood of them happening. Because when something like this is analyzed from such a good scientific perspective, there really are interesting things to be learned from it! :D Thanks for these great videos!

[@metal87power]

why unlikely?

[@theskorpian]

@@metal87powerprobably the fact that there's literally zero evidence to suggest, much less support, the hypothesis.

[@user-hh9kz8ng4d]

Unlikely is what the government would say if they found technology better than ours in an archaeological dig, they don’t want us to know the truth

[@fuckingblackgod]

@@theskorpian Absence of evidence is not evidence of abscence.

[@Dover939]

@@fuckingblackgod Which makes it extremely unlikely as the person you quoted said.

[@johnderoy916]

Thank you for pointing out that we have an example of ONLY 1 when dealing with inhabited planets in the universe - not that there are no other only that all of our experience and knowledge is from a sample of 1 - which is meaningless for drawing conclusions.

[@justin-tyme]

There was a great episode of Star Trek Voyager (Distant Origin) that had this premise... "We are not immigrants!" Very cool.

[@exscape]

One of my favorites! And the first thing I thought of when I saw this video title + thumbnail.

[@eSKAone-]

I love this episode 💟🌌☮️

[@anthonymudge9768]

I like how this possibility was explored in both Doctor Who and Star Trek Voyager

[@piotrd.4850]

"Distant Origin" - yeah - beautifully started episode, somewhat simply ended. And Voth, being so powerful - strange they haven't move to earth to e.g. erase proof of distant origin. But beaming Voyager with shields raised inside was really something else even on ST scale.

[@X-jaybyrd]

this was my first thought when learning about plate tectonics in elementary school, funny how our imaginations can lead us to similar ideas.

[@zacharywong483]

Superb video, as always!

[@Nethershaw]

I really, really like it when we do this. This thing is very, very, very, very, very probably not true -- but we stand to learn an awful lot if we explore the possibility anyway.

[@Jason75913]

The better way to put it (and the point of this vid): we stand to learn a lot of we explore _how_ to explore the possibility.

[@----.__]

It's like those matrix logic puzzles, you know the ones, for example there's 5 people who live in 5 coloured houses and have 5 different jobs and keep 5 different pets etc etc. The clues those puzzles give aren't so much the information that's in black and white, you have to infer what can and can't be true and by eliminating what can't be true you find the truths that aren't even written. [edit: they're called "logic grid puzzles". Never bothered to find out the name until today! If you haven't tried them before then give them a go, they're a lot of fun and good exercise for the mind]

[@jakobthomsen1595]

How long (on average) would artifacts survive on the moon? Would the chance of finding something there be larger or smaller than on earth?

[@ILLUMINATED-1]

Radiation from the sun would first bleach then break down many surface artifacts, I believe. Theres also cold-hot cycles and impacts that complicate things.

[@DaveCompton5150]

I've seen estimates that it would take 10s of millions of years for the Apollo landers to be destroyed by micro meteors

[@stevenjones797]

Voyage To The Bottom Of The Sea, season 1 episode 20: “The Invaders”. Seaview discovers the remains of an ancient civilization. Creepy yet thought provoking episode.

[@uncletaylorify]

Star Trek Voyager had this storyline. A species of dinosaur evolved into a civilization on Earth. They became technological and went out to the stars before the meteor strike.

[@SometimestheY]

Many species of dinosaurs were around for a looooong time. They had large, complex brains and are some of the only other bipedal creatures, with grasping hands, we know of to have ever walked this Earth; many of their bird descendants build homes, take care of their young, use tools, and are capable of song and complex speech patterns. It really doesn't seem that far-fetched to me that there might have been some level of at least pre-industrial or early industrial dino civilization. Glad Space Time is finally spreading the word. 😉

[@rhino6139]

Draconian are related to dinos, the way man is to chimpanzees.

[@davidmhh9977]

That's almost existentially horrifying, to think that bird intelligence might be the result of a species with human-like intelligence, decaying for millions of years. I'd be like humans evolving back into ape like primates

[@Iv_john_vI]

Tyrannosaurus Rex having tiny hands definitely suggests they were Jedi.

[@smartguy-lx9im]

Bravo for tackling a topic that is usually considered too "fringe" and "silly" for mainstream science to consider. Keep up the great videos.

[@VestedUTuber]

So, one thing about the issue with early fossils getting subducted, while many probably did, many of them probably would have accreted into sedimentary deposits above the crust itself. Might be a good idea to check around subduction faults, though you'd have to dig VERY deep into them to have a chance to find anything.

[@princecharon]

Something that I've been wondering about for a wile: if a pre-human civilization made it to the Moon and left behind some probes, lander decent stages, and similar stuff, how long would it be recognizable for? Like, there's no meaningful atmosphere and such, but there's also no protection from meteors, so I wonder if the chances of finding anything are higher or lower, even if they had a lot of stuff up there (e.g. sapient dinosaurs who watched the K-T Impact from their moonbase, but eventually died out themselves).

[@xitheris1758]

This, combined with the Martian Canals, is my favorite retro scifi concept.

[@AngeloXification]

Just when I thought I couldn't love this channel any more

[@dxtrum]

Right

[@The-Fool1212]

Could you imagine a somewhat nearby habitable planet just suddenly developing intelligent life millions of years from now and humans simply witness.

[@bebopcowboy9934]

Some people do not like to speak about him but HP Lovecraft was right with many Things in his Stories, May by random but maybe on this one too. See , most of the Ruins got destroyed but even those left by sumerians are older than most would believe and who knows what lays under the seas, under Mountains and got melted by. Continental Drifts

[@3_Dogs_In_A_Trench_Coat]

If there was another civilization I think it stands to reason that they had the same doubts as us. And if it was the case they maybe -juust maybe- had thought of putting a memento in a place more suitable for a long - lasting object like a monolith (Cue in Also Sprach Zarathustra...)