The Silurian Hypothesis｜Stuff You Should Know

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Welcome to Stuff You Should Know, a production of I Heart Radio.

Hey and welcome to the podcast.

I'm Josh and there's Chuck and this is Stuff You Should Know.

It's just Josh and Chuck today.

That's all right.

Don't freak out Chuck.

We're going to make it just fine.

I'm just glad we're recording.

This is just a little inside baseball here.

This is our third attempt at this recording session.

Yeah.

Well you defused my inside joke to you that I didn't have enough time to prepare for this

episode.

So yeah.

My internet went out because of a wind storm last week and then we were like you were

kind enough to be like, we'll just do it next Thursday.

And then yesterday your internet had problems.

And I said, well let's just do it tomorrow morning because Friday morning at 8.55 is when

the voice is in perfect shape.

Right.

Which was also very kind of you.

So we've been kind to one another throughout this ordeal.

You've got to do that people.

If you want to stay married.

Yeah definitely.

You want the other person to hold your hand.

You better be kind.

But I'm excited to finally, and you know probably it was probably good that I had a lot

more time with this because this is one of those sort of thought experiment.

Mm hmm.

Get your brain in the right frame of mind kind of episodes and we love doing these.

And this is going to be a good one.

Yeah.

For sure.

So what we're talking about today, Chuck, is the salurian hypothesis.

Which if I could do anything with this thing, I would rename it.

I'd be like guys, that was a terrible decision.

I keep listening everybody.

So right.

Exactly.

So the whole thing came out of, we'll explain in a second, but we should probably talk

about where it came from and why we don't like this name.

The whole thing came out of a meeting between a guy named Adam Frank, who's an astrophysicist

at the University of Rochester.

And a guy named Gavin Schmidt, who's the big wig director for the Goddard Institute

for Space Studies, a NASA joint.

And Adam Frank went to Gavin Schmidt and said, hey, I'm trying to figure out if we

could find ancient, defunct civilizations elsewhere off of Earth.

What would I look for?

And the reason he was doing this, it's an answer to the Fermi paradox.

Where is everybody?

Well, one answer is, well, they were here, but now they all died out.

So Adam Frank is looking for evidence that they were there.

And Gavin Schmidt said, let me just stop you right there and up the ante here.

Well, actually, do you know what Gavin Schmidt said?

He said, let me tell you something, Professor Frank.

Hey, and Professor Frank said, oh, God, I've had a dime for every time somebody did that.

Right.

So so close.

Yeah, Schmidt was like, hey, buddy, would you say I'll one up you?

I'll up the ante.

Okay, I'll up the ante here.

What if it's planet Earth?

And what if there were ancient civilizations here, my friend?

And they said, check, please.

Yeah, Adam Frank just vomited directly all over Gavin Schmidt's desk very famously.

Yeah, I mean, I think they sort of started chatting about this thing.

And we should point out that, you know, what we're going to, they wrote a paper, we'll

get to that in a second.

And they named it, salarion hypothesis.

But neither one of them think like, oh, I think this is what happened.

Right.

It's more, you know, it's a thought experiment.

It's what happens when two remarkably intelligent people get together sometimes and take

LSD.

One of the other things about it that I think makes it worthwhile too.

First of all, these guys are the first scientists to seriously explore the idea, which you can

apply science to anything like that.

And they, even though they don't think it is correct, they don't rule it out.

Yeah, you can't rule it out.

There's not enough information to rule it out, right?

Yeah.

But the other thing that it does is it provides kind of like a guide to see what we're doing

now.

Okay, we're going to leave in the far future as well.

Yeah, absolutely.

So I imagine they went to another venue, they went to a bar afterward to have a drink.

Yeah.

Keep this party going.

And they were like, well, you know, there's been enough time for something like this to

have happened.

Yeah.

Because when you look at the fossil record, the oldest thing that we know of is a cyanobacteria

fossil that's about three and a half billion years old that was from the ocean.

Yeah.

If you're talking about complex life, then you only have to go back about 540 million

years ago to the Cambrian explosion.

So like anything beyond that was, you know, stuff like cyanobacteria that we know of at

least.

So any prior intelligent species wouldn't theoretically be older than that Cambrian explosion.

Yeah.

And they call it an explosion because everything went from single-celled organisms like you

were saying to like basically all the types of animals on the planet today.

Yeah.

Just like it exploded.

It's just the best name for it.

You really can't add to that.

But there's another guy, another character we need to add here.

And his name is Jason Wright.

I like this guy.

He's an astronomer at Penn State.

And he said, whoa, whoa, guys.

And this is in a separate paper that I think even predated the saluri and hypothesis paper.

He was saying next to them over hearing them at the bar.

Right.

They were like covering their work while they were there.

Exactly.

So Jason Wright says, not to them directly, but in general, he's like, okay, we don't know

that you have to stop at the Cambrian explosion to look for intelligent life on Earth in

the past.

And the reason why is because we have a really like that's using a really limited definition

of life.

That's using the kind of life that has certain body plans with the central nervous system.

Some have like backbones, some don't, some are jellyfish.

Doesn't matter.

Like what if there's other kinds of life out there?

What if some of those single-celled organisms had gotten together and formed like a hive

mine colony that was capable of intelligent industrialization?

We wouldn't know that.

Like think out of the box, guys.

Yeah.

Exactly.

Because, you know, it's hard to wrap your head around.

All we know is us in what happened with the development of how we got to now.

Yeah.

So he's like, you know, turn that off everybody because that could have happened what

Josh Clark just said.

And they're like, who's Josh Clark?

And they say, you'll find out soon enough.

He said, or maybe there was another like Cambrian like explosion that happened like way,

way back before that.

And maybe it's, maybe they didn't leave any fossils behind or so few that we didn't

find them.

Or maybe, you know, there was a cataclysm that destroyed everything like there was this

complex life.

It destroyed everything.

And it kind of just rebooted the system with these single-celled organisms.

And that's what we know is the start.

Right.

Yeah.

And then, yeah.

Whoa, buddy.

I know.

It's pretty cool.

Can I pay for this guy's drink?

Yeah.

Can I buy you a beer?

So Gavin Schmidt and Adam Frank are like, we think we're on to something here.

Let's kind of flesh this out a little more.

And I think it was Gavin Schmidt who suggested they call it the saluri and hypothesis.

And the reason they call it the saluri and that's a, I think, a period or an epoch or something

in Earth's history 500 something million years ago.

But they weren't naming it after that.

They were naming it after a race of lizard people who are characters on Dr. Who.

Yeah.

Do you have any Dr. Who experience?

None.

I feel like it's like this whole thing out there that's just waiting for me to meet it.

And I'm like, I don't know.

I mean, I've never, I don't know anything about it, but I just caveat that because there

may be emails coming in that are like, they're not lizard like people.

They are this.

Like, I have no idea.

I looked at pictures of them like you did and they look like lizard reptilian type creatures.

They do.

I mean, for all in some cases, if you're not super into Dr. Who, they're lizard people.

I really, really hope so.

The reason that they named it after this race of lizard people and Dr. Who is that on the,

in the Dr. Who universe, they lived about 300 million years ago, which would actually

make them place them in the carboniferous period, not the saluri and apparently all Dr.

Who fans are aware of that.

Right.

Because they're all Dr. Frank's.

Right.

But they supposedly survived a bunch of cataclysm here on earth by moving underground and

hibernating until things cooled off a little bit and now they're back in the Dr. Who

universe.

So they would be like the ancient civilization.

And so there's two reasons why I find that unfortunate that they named it after that.

One, it just makes the whole thing silly to a degree, apologies to Dr. Who fans, but

it like this is an actual like academic exercise they're engaged in.

Yeah.

And it's a thing out of the case.

It's a tea.

I mean, again, we're not saying Dr. Who is silly, but it'd be like us coming up with

like the family ties hypothesis or something.

Right.

Like his name, Dr. It's TV show.

It says like before you even read the abstract, don't take this seriously, but it's meant

to be taken seriously.

It's not tongue and cheek at all.

Yeah.

The paper isn't at least or the hypothesis.

The other reason why is because every single author who wrote any piece or article about

this hypothesis afterward uses a hypothetical lizard race to discuss what we would be looking

for.

And it's so obnoxious, man.

So we are not going to do that.

No, no.

We're not even going to try to guess what they would be like or look like.

They're just the hypothetical ancient industrialized civilization that we're looking for.

So if we're looking for something like that here on earth chuck, what would we start to

look for?

Well, and I mean, those are sort of the questions these guys started.

I guess they went to another bar and started asking.

They're pretty sloshed at this point.

That's going to say.

And they start asking even more questions.

I guess after they got over the, I mean, hopefully they didn't have to argue about

Celurian.

I'm praying they were both Dr. Who fans and that Dr. Frank didn't have to convince old

Gavin, you know?

I think it might have been the other way around and based on the titles, I think Frank

would have had to go along with it.

Okay.

Well, either way, they started to sort of ask these big questions and what it really

comes down to are two main questions.

What should we be looking for?

And in order to think about what should we be looking for, a good place to start is,

well, what are we leaving behind that a future archaeologist or geologist might look

for?

And when they started poking around a little bit, they found that, you know, there's some

stuff here that does bear a resemblance to like possible signals that something could

have happened as far as an ancient industrialized civilization that just went away.

Like, you can't hear it, but my jaw just dropped.

Right.

All right.

Josh's jaw is on the floor.

We're going to seek some medical attention and we'll take a little break and we'll be

right back.

I'm going to ask you guys.

That's a great name.

That's the name of it.

Because of corrosion and erosion, so without that, even though it's hard to imagine, everything will eventually be gone.

And we're talking about in the grand scheme of the big, big timeline, so like hundreds of millions of years.

Yeah, yeah.

But for a city itself, I mean, apparently water intrusion is a big problem for all of those tall buildings, as well as erosion and corrosion and all that.

It's not going to take millions of years for them to go away.

We're talking thousands to tens of thousands of years.

Yeah.

And our cities will be just completely rubble, especially ones that are built on like solid ground or rocky ground, well above sea level.

Because those are the ones that are most like open and left vulnerable to the processes of erosion that sweep across Earth's surface and wipe the whole thing clean.

Yeah.

Yeah, it wouldn't take very long. The stuff that's underground might be a little more easily preserved.

Like, you know, under any city, there's a huge network of infrastructure, pipes and cables and tunnels and hard hats and stuff like that.

That conceivably, even after the city above is long gone, that stuff could be preserved to a certain degree.

Yeah, for sure. And we should shout out this guy that, did you dig him up or was that Livia?

I think Livia found him.

Yeah, his name is, starts with the J, but is Jan Zellis-Chevitz.

And he's a paleontologist at the University of Lester.

Mm-hmm, nice word.

Oh, boy. In the UK. And we shout him out because he, you know, he's sort of let us down this path of looking underground, potentially looking underwater.

Because things would just deteriorate a lot slower down there. But he's just a guy, I just want to recommend if you're, if you want to get into some head, he sort of, yeah, YouTube stuff.

Just Google Jan Zellis-Chevitz. It's Z-A-L-A-S-I-E-V-I-C-Z.

Because I went down a little, because we had so much extra time.

Yeah.

Just a little bit of a wrap at all.

Yeah, I like watching this guy. He has a bunch of YouTube's, or he's speaking to university groups and classrooms and things.

And he's just super smart and interesting.

Yeah, this stuff he's into is super cool too. But yeah, he himself gets it across really well.

I like that.

Yeah. So he points out, he was the one, I think he chose San Francisco. San Francisco is a goner.

It's not going to be around very long. Once we're gone.

And by the way, I keep saying once we're gone, remember that amazing 2007 book The World Without Us by Alan Weissman?

Never heard of it.

Oh, yes, you have. It was like all the thing back in 2007. They made like TV shows about it and all that.

So this guy basically went to the trouble of figuring out in five years, 10 years, 50 years, 100 years, 1000, so on.

That sounds familiar.

What the planet would be like after if humans just suddenly vanished.

And like he goes into detail of like the processes of erosion and corrosion, what effects it's going to have. It's just so fascinating.

That's super cool.

Yeah, it is super cool. And like the series, at least one series, I think I'm like science channel or something like that was worth watching too.

But that, I mean, that has a lot to do with what we're talking about.

So the top side city's gone. The stuff underneath might be preserved.

But the cities that are built along the water.

And there's a lot of cities that are built along water. They like say New Orleans is actually built below sea level.

When people are gone from New Orleans, New Orleans is going to go away really quick.

But it will probably get preserved or at least covered over if not preserved by a lot of the muck, the Delta muck that's brought down the Mississippi River.

And that will conceivably create the conditions to preserve the whole city in some form of fashion.

Totally. But, and you know, a lot of the thought experiment is like introducing things and poking holes in it.

There's not a lot like, you know, if you live in an urban area, it's kind of hard to think that there's not much urban area in the world.

But there really isn't. I think the liberal estimates have it at about a little less than 3% like 2.7, 2.8% of the world has been urbanized.

Some people put it as low as 1%. So there's a lot of just land out there still.

So if you're looking for an ancient civilization, I mean, who's not to say that it could have been like 50% of the earth.

But chances are it would be something a little more like what we're doing.

For sure. And so like you were saying, like that's one of the cool things about this as a thought experiment.

Like you raise this point and then you poke holes in it. But then sometimes you can kind of support it instead.

And so like a legitimate question would be like, why are we assuming that an ancient civilization from millions of years ago in Earth's history had cities.

And the reason why if they have any kind of intelligence, typically the more of an intelligent organism you put together, the more advanced it becomes.

Like 12,000 years ago, there was something like 15 million people across all of planet earth tops.

But then as we started to grow in density, thanks to like agriculture and animal domestication, all of a sudden our technology started to develop a really rapid pace, geologically speaking.

And now here we are. So we could assume that there'd be some form of density because you need X number of intelligent organisms to advance to an industrialized civilization.

One would imagine. So there's actually a legitimate reason to think that they would have cities that we could look for.

The problem is this Chuck, and you know this as well as I do. Yes.

We'll see. The Earth does not like things like cities and ruins or fossils. Let's talk about fossils.

Yeah, I mean that seems to be the next best place to start looking if let's say the buildings are gone. Fossils are how we know what happened in our distant past.

But fossils are tough just because of how rare they are and how hard it is to make one and how sort of lucky it is that they happen to begin with and that we find them.

The T-Rex is a great example just a little like back in the envelope math some estimates say that somewhere in the neighborhood of 20,000 T-Rexes at any given time during their run were walking stomping around planet Earth with their tiny little baby arms.

They were around for about two and a half million years that comes out to roughly 127,000 generations on the lifespan of a T-Rex. So we're talking total roughly of course about two and a half billion individual T-Rexes that lived and died at any point in their history.

And we only found 50 fossilized skeletons which is about two million of 1% of the total population.

Yeah, I should forewarn you that two billions of 1% is my math personally. But I did use it online.

I used to calculate it like three different times to make sure it's accurate my friend. I know the math people are always checking you. I was about to say getting your back but really trying to prove wrong.

I got a target on my back that's what they're trying to get.

As silly as some of that stuff was with the great movie don't get me wrong. But you know the mosquito being covered in amber. Like if you if you look at that movie like that one mosquito got trapped in amber and that's kind of what we're talking about here is just sort of the dumb luck of the fossil happening to begin with a.

And then that fossil that's buried eventually getting pushed up to the earth surface where we can find it right but within the window between it popping up and it being findable to it eroding to where it's not findable anymore it's like it's it's all I mean that's why we don't have a you know billions and billions of fossils is because it's just really rare to make one and find one.

Yeah not just making one but yes finding one it's all a product of time and space in a really complex formula and I saw in an article called how can I become a fossil by John Pickerel from 2018 on BBC really well worth reading.

Did I say start listening to the dooby brothers.

Oh yeah RIP Dickie bets.

Well that all my brothers but sure well yeah I know I knew that but yeah okay I mean they're both brothers yeah yeah same time period RIP Dickie bets it was it's

a tough one if you had been in my brain it would have been no I got you of course and it's also 920 so John Pickerel cited an estimate that one 10th of 1% of all the species that have ever existed has had one of their

individuals fossilized. Oh wow so just really tiny tiny percentages of fossils are ever created but and also I got to just say this quote to

there's another article called the Anthropocene as a joke. Yeah I thought you're going to skip this one is great.

Yeah I got named Peter Brandon who's a science writer wrote it and basically he's explaining like just how insignificant humans have been on Earth

even as much as we've affected Earth just how insignificant it actually is and how easily Earth will shake our stuff off.

Yeah but he had this great quote I think you should say it.

Oh okay. Do you know where he's from so I can prepare.

No let's say Austria.

I mean I guess it's sort of German. I'm just going to read him as American.

This is a great quote each fossil was its own miracles sampled randomly from almost 200 million years of history a few stray wind blown pages of a library.

Isn't that great. Yeah that really drives it home.

It really does so hats off to Peter Brandon and John Pickerel definitely go read those and also go watch YouTube's of Yon Zellushevich.

Right. Sileshevich. Can I manage it. Right but with a Z. Yeah.

So all of that said though we have discovered really really old fossils.

The old is hominid our ancestor the oldest indisputable ancestor to humans.

Austria the pithicus and a men'sus was walking around four and a half almost four and a half million years ago and we have a skeleton of that guy.

So as miraculous as fossilization and discovery of fossils is it does happen.

Yeah absolutely and that's hominids our old buddy.

Yon Zellushevich is like you know what else could happen is we're creating a bunch of potential techno fossils as we advance.

Like somebody could find a smartphone one day somebody could find a grocery bag that's been fossilized.

The more likely thing that's going to be found is not some smart phone that you could plug in and then reboot.

Right. Maybe like let's do a picture. But it might be something like a brick or a glass bottle that's you know that clearly human made that's like artificial in shape and it may be stamped with like a company name or something like that.

Like something like that is is more probable for a future anthropologist to find as a techno fossil.

Yeah so or plastic right. Plastic is another good one. We actually don't know how long it takes plastic to break down to its constituent parts.

We know that it breaks down into really really small particles but there's still like micro particles of plastic.

It's like intact particles of plastic right.

And if if a future like race discovered our plastic they'd be like this is really bizarre because by definition the plastic we make is artificial.

There are like polymers in nature like cellulose that are an analog to our plastic but all the plastic we make is not found in nature.

So if they found that they'd be like this is kind of weird what's going on with this. Yeah for sure.

And then chicken bones too Chuck. Have you ever seen it was an Instagram account it may have been called Atlanta chicken bones.

No.

That were just these great pictures of chicken bones in parking lots and sidewalks all over Atlanta.

Right so that's a really great point. There's the people who are like all bully on the Anthropocene.

The idea that the humans are creating it our own geological era or epoch say like chicken bones are probably a pretty good bet for like fossilized evidence of our presence because we raise and kill so many chickens it boggles the mind their bones get everywhere.

And they are anatomically different from all other kinds of chickens because we bred them to be different like have huge breasts and not be able to walk and all sorts of terrible stuff.

Yeah.

So if you if you found other chicken bones in the fossil record and then you found our broiler chicken bones you'd be like what is this and also why are they in Antarctica.

Right.

I also want to point out since I brought up Atlanta chicken bones I am a lover fried chicken as you know yeah it's probably my favorite food and I have been known to have car chicken.

As long as there's no shower chicken I'm still it's still going on the sand that I'm.

No you want to keep it crispy you don't want any humidity in there but I have always resisted the urge to toss my chicken bones because I have dogs and I walk dogs and if you're not paying attention that dog can snap up

a chicken bone on the sidewalk pretty easily so just a PSA there trying to keep those chicken bones in the box.

Yeah and chicken bones can splinter so readily that it can really hurt your dog's throat stomach you don't want a dog eating chicken bones okay.

Yeah did I ever tell you this will be quick about when my deceased dog Buckley ate an entire drumette that fell off the grill.

No.

It popped off many years ago Buckley left this but I looked down I was like shoot chicken bone or chicken drumette and it was just gone and it was gone so fast and Buckley was there but I was like he wasn't chewing or anything.

I was like what happened to that thing ten minutes later.

He barfs up a hole he swallowed it whole a whole chicken drumette that was still steaming from the heat of the grill so God so it was like I mean thank God he did that because that would not have been good.

Yeah he swallowed that thing like a pill and when he threw up he wiped his mouth he's like totally right.

Yeah I think he thought it was worth it.

So I said something earlier Chuck we were talking about ruins fossils all that stuff I said that earth doesn't really like that kind of stuff and I was right.

Are you setting me up yeah well because here on earth we have plate tectonics we have a situation where if you're talking about the ocean crust it's a duck's below the the lighter continental crust and it's going to push everything down down down.

To the mantle where it melts and then eventually comes back up via like a land volcano maybe an undersea volcano to form a new crust and it's just like this this giant super super slow recycling conveyor belt.

Yeah it takes I think on average about 250 million years for new crust to go through that whole cycle that's just on average you can take hundreds of millions of years longer yeah take less but that's just kind of generally how slow it is the point is is that after X number of millions of years.

That crust is what in everything attached to it is totally gone once it hits that mantle it doesn't discriminate everything gets melted everything gets melted in the.

What about on land well land is not subject to to the forces of like a subduction right but it does have that erosion through wind and water and everything just kind of gets recycled in its own way plus also the plates that do collide with one another and there's you know continental fault lines obviously to the producer of the quakes when they collide the stuff anywhere near those.

Anywhere near those edges gets all kinds of messed up yeah and that's how a lot of mountain ranges form and then there's the Himalayas the thing is is that erosion that process of erosion that completely recycles earth surface over X number of years.

In 88 million years the Himalayas will be gone it'll just be a meadow where they were.

That's one of my favorite sort of facts of the show right there yeah it's hard to imagine the stuff but yeah what is it eroding at like point one millimeter per year.

And again we're talking these we're talking on timelines of hundreds of millions of years here right.

So 88 million years yeah that's it just go romp in the meadow yeah because even if we're just going back to the Cambrian explosion and you can argue that you can go back further like Jason right to it but even if you're just going back 540 million years.

That means continental crusts have like reinvented themselves twice since then the earth's surface has been recycled countless times apparently the oldest surface stretch of earth is only is like less than 2 million years old.

Oh geez that's really young yeah the reason all this stuff is hard to imagine like the Himalayas going away because our sense of time is so limited to about the span of a lifetime.

Yeah plus a couple of decades maybe that when we start to think it tends in in hundreds of millions of years into the future of the past we just stop it just doesn't it doesn't really make sense to us unless we really apply ourselves.

Yeah that's like this yeah exactly.

So you've got plates colliding you've got glaciers do all sorts of they move entire regions around like bulldozers but even something as humble as the movement of earthworms through the soil over enough time that's going to erode fossils ruins subterranean networks of pipes and essentially we're back to square one trying to figure out what to look for for an ancient civilization.

Are we done almost all right maybe we should take a break and we'll come back and talk about why we're striking out and where we go next.

When you think about the future what kind of technology do you envision whatever the future holds artificial intelligence will undoubtedly be at the heart of it all join Graham class as he hosts season two of technically speaking and Intel podcasts from Ruby studio and partnership with Intel explore the future of technology that's rapidly evolving our world today with the help of AI.

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Stuck's net who sucks net stuck net I don't know you know it's stuck in this sucks net.

It's a great name.

Yeah, whoever that's the name of it.

It's a great name.

All right, stuck's net with the with an X.

Okay, Chuck, so we've seen that we can dismiss the archaeologists.

Thank you everybody and bring in the geologists.

Yeah, like take your whip, take your Fedora, pack it all up, go take a break because the geologists are on the scene.

You can doctor Jones, you can take a seat.

Right, so I can't even like what are the geologists like they just they don't have a movie franchise like the archaeologists do.

Yeah, I mean, they're not looking for grails or looking for residue, so it's not it's grabby.

Yeah, I guess they're the thing that you most associate with is like a slight cough in a really large empty room.

Yeah, like there would never be a movie called Indiana Jones and the ancient tree ring.

No, you know, unfortunately, but that's what we're talking about is the fact that if we were to have an idea,

if we were to have a future geologist look back, that's what they would likely be looking for.

Like forget the fossils, they're going to be looking for just little bits of residue by looking at these tiny little layers of sediment that we deposit every day all over the place.

That eventually becomes rock and this is how we've you know, look back at our own past to learn things.

That's how we knew that the dinosaurs were exploded basically because of that asteroid and that Cambrian explosion happened because we have studied geology.

Yeah, we've learned to study those layers that get put down and put down and the problem is on Earth's surface as we've seen.

There's the process of erosion.

Yeah.

There's an entire layer across the whole globe. It's not just in one spot, but there's a billion year stretch of the geological record that's just gone.

It's missing.

Crazy. I'd never heard of this.

Yeah, I hadn't either. It's called the great uncomformity.

And like we'll just never know what was there, what happened during that time because there's no record of it.

They think that it was just a period where there wasn't a lot of sedimentation put down, but there was a lot of erosion.

So some people suggest that it was during snowball earth, one of those periods where like ice sheets cover the entire globe three miles thick and that they could erode stuff, you know, pretty cleanly across the globe.

It's a pretty good, pretty good theory, but stuff like that happens.

And when we're looking on Earth's surface, you run into problems, but because the oceanic crust takes so much longer to recycle, we could look there and can see we'll find something hundreds of millions of years old.

Yeah, I also got to say snowball earth is, I mean, that's the next great Netflix show waiting to happen.

Maybe that's about an adventurous geologist.

Maybe so.

I love it. So yeah, going back underwater seems to be a better bet than because of stuff like the great uncomformity.

Going back underwater where that process is of wearing stuff away is much, much slower is probably a better bet for us and a better bet for future geologists.

Yeah, because all the stuff that enters the ocean or is born and lives and dies in the ocean, it becomes detritus that eventually tumbles down to the ocean floor.

And it gets locked in and sediment there and it happens really, really slowly.

I think 0.8 centimeters every thousand years is about the average sedimentation. So that means that so far we have accumulated about 0.16 centimeters of ocean sediment that would bear our presence, possibly even bear the signals that we ever lived.

But we're doing, we're adding to it every day. Thanks to things like nitrogen fertilizer that we overuse that enters the water sheds and eventually goes to the ocean and then goes and gets trapped in sediment.

And so if you were a future archaeologist or geologist and you were looking at the layer where we existed, you'd be like, what is all this nitrogen suddenly doing here?

And then also what are these weird polymers that used to be our plastic from all the stuff, all the plastic that ends up in our oceans, those will eventually fall down to the bottom and become trapped in the sedimentary layer too.

Yeah, so that supersoaker that your kid lost beyond the point where the waves would bring it back in is eventually going to end up at the bottom or the trash that is floating around the ocean.

All that stuff is going to go down as well. And so this is going to lead behind like a trace, a sediment trace where a future geologist might say, well, hey, I see that there was this specific time period, 100 million years ago, but there was a spike in nitrogen or a spike in these weird,

these weird, human-made polymers, or maybe they didn't know that there were humans, but either way, like...

Yeah, something that doesn't jive with what we have going on today, there are all these weird spikes, so there was clearly something going on in this time that we now think of as our time here in Planet Earth.

Yeah, because that's how we find mysterious signals in the geological record. You compare it to what's above and what's below it.

And if something suddenly appears or disappears, you know, like it's like, look here, look closer here. Radioactivity will probably be a marker that will be behind two from all the nuclear tests.

There'll be plutonium 244 and iodine 129, which have half-lives in the millions, tens of millions of years.

If we end up going out in a massive nuclear war, you bet that will leave quite a signal in the geological record. And one of the other things about leaving a record in oceanic crust is that the Earth goes through cycles of cooling and warming and cooling and warming, and when it cools, the sea levels decline.

It gets sucked up into ice. And so what's under the ocean may end up hundreds of miles inland, future archaeologists to find, probably more easily than they would if it were underwater at the time.

Yeah, for sure. So, you know, sort of striking out all over the place, such that our old astronomer, friend Jason Wright, is like, maybe Earth is not the place to look.

Maybe we should be looking on a place like Mars that doesn't have plate tectonics and is probably a better, more hospitable place for some ancient thing to be discovered one day.

Yeah, and not necessarily a Martian civilization, but an intelligent Earth civilization that sent probes to Mars or something like that.

Yeah, the European Space Agency also points out that if anybody had been around to send a probe out into geosynchronous orbit, the furthest reaches of geosynchronous orbit around Earth, it would still be there.

It's orbit wouldn't have collapsed yet. So, you know, we need to look for 66 million year old probes spinning around Earth. That's a good start too.

Yeah, so all of this sort of presents a paradox. It's pretty interesting, which is that if you're going to be an industrialized civilization that lasts long enough to leave something behind for some future geologists to find, then that means that you found some sort of sustainable way to survive.

And if you found a sustainable way to survive, that means you're not making as much of a findable impact on Earth, you're living more sustainably.

And so you're not dumping plastics into the ocean or nitrogen into the ocean and sort of cleaning up your act and erasing your path a little bit better.

If you're not doing that, then that means you haven't found a sustainable way to live. So that means you're going to, as a society, die out much quicker.

So you're going to be just a shorter blip. So either way, it's just going to make things more difficult.

Yeah, whether you're long lived or short lived, the record you leave is going to end up just being a blip in the geological record, right?

Yeah, again, on that huge timeline.

So, like, I'm sure some people are pulling their hair out. They're like, how then? Like, it is the impossible to find signals that an ancient civilization existed or what signals will we leave to?

And yes, there are. And what you want to look for is not the like traces of fossils or strange appearances of elements in the geological record and sediments.

Instead, you want to look at the impressions that the effects of those things had on Earth, because those get locked into geological records and they can stay around for a very, very long time.

So much so that we can look back into Earth's far, far, far distant past.

Yeah.

And we see signals that were like, can't rule out that this some industrialized ancient civilization produced these effects on Earth, because we don't know what happened.

Yeah, exactly. And what we're talking about is something called a hyperthermal event, where three things kind of line up, which is an abrupt extinction of, maybe not everything.

But many, many, many species, that's pretty obvious, that coincides with a buildup of carbon in the atmosphere and a lot of rapid coastal erosion.

All of those three things happening at once is called a hyperthermal event, and it's a pretty good indication that something really, really big happened to wipe out most everything.

Yes. And usually the hyperthermal events we found are caused by negative carbon isotope extrusions, which is basically just a different way of saying a ton of organic CO2 was pumped into the atmosphere.

And it had all of these telltale marks of sea level rise leading to erosion, mass extinctions, dogs and cats living together, all that stuff.

And so if we look in the past, there are events that coincide with this. One of them is the paleocene, eocene thermal maximum, the PETM.

Yeah, it took place about 56 million years ago. So basically after the dinosaurs died out and right after mammals started to take over Earth.

Yeah, it got really hot. And I was trying to figure out how hot that the surface temps in the Arctic sea were about 73 degrees Fahrenheit.

So that's what you find today around the panhandle in the Gulf of Mexico. These are the Arctic seeds. Today the global annual surface temperatures about 59 degrees Fahrenheit, 15 Celsius.

Back then it was 90 degrees Fahrenheit or 32 degrees Celsius. That's the global temperature, the average across all of the globe. So it was really, really hot. And they have traced that to tons of carbon dioxide suddenly appearing in the atmosphere causing all these changes.

Yeah, and that lasted for about 100,000 years. But that's not the only one. There have been other events similar to that in the Cretaceous period, in the Jurassic period, in the Paleozoic era.

And then in the six million years since the PETM, the Paleocene, Eocene, Thermal Maximum, there were even more of those hyperthermal events. And again, they sort of all bore the same similarities, right?

Yeah, because there's only so many ways that Earth responds to being messed with.

Yeah. And so like all of these things kind of do bear a striking similarity. And there are things, there's natural things that you can point to that could have caused them, like massive volcanic activity across Earth.

Or a sudden huge deposit of shale ended up in the mantle and got recycled very quickly. And all sorts of CO2 was released in the air.

Who knows, but what Schmidt and Frank basically point to is like, and again, they don't think this is correct. They say, like you can't rule out.

Yeah, yeah.

That this is a marker of an ancient civilization, creating climate change in exactly the same way that we're creating climate change today.

Because we are laying down the foundations of a geological signal that will be detectable hundreds of millions of years in the future as a hyperthermal, exactly like the ancient hyperthermal we've discovered in Earth's past.

Yeah, which is basically if we do ourselves in with climate change.

Yeah, because they're predicting if we just keep going fossil fuels just for the rest of the century, by the end of the century,

we'll have increased the global temperature by about 4.8 degrees Celsius, which is huge.

That is that qualifies as a hyperthermal maximum and that PETM, like the biggest hyperthermal maximum that ever happened all of a sudden, that took place over like a thousand plus years.

We're doing this in a couple hundred years. So it will really stick out in the geological record.

Yeah, I think the PETM had a five to seven Celsius degree rise. And if we're looking at 4.8 in that span of time, that's trouble.

Yeah, and that's just by the end of the century. Who knows if we just keep going?

We're not quite sure when the whole thing will steady itself out and what the peaks will be when it does.

So there's one other thing that I found really interesting is that the fossil fuels that we're using to create inadvertently this hyperthermal and earth's geological record is created from the mass extinctions from the past, those dioths, turned into fossil fuels that we use today to essentially add all that carbon to the atmosphere, which is creating these warmer conditions.

Yeah, and then if you take it one step further, we're eventually going to create these mass extinctions that will create the fossil fuels for another industrialized civilization to come tens of millions of years in the future.

That's right. We're just insignificant aren't we?

Yeah.

But also, over a really significant somehow.

That's right. If you really want to get that driven home, go read Peter Brandon's, the anthropocene is a joke.

It almost made me feel like fine about climate change because it just in the grand scheme of things. It's so insignificant. I had to be like, no, no, it matters. It's important to stop thinking like that.

Yeah.

What do you mean?

So you got anything else?

I got nothing else. This is a long way to trust and a lot of fun.

Yeah. Let's hope we remembered to press record.

Oh God. I would just retire.

Well, since Chuck said he would just retire, of course, that means he's triggered listen or mail.

Yes, this is a story from Dylan. This is one that I know about or knew about, but I don't know if we ever talked about it, but it's a pretty interesting little thing.

Hey guys. I've been listening to you for about two years. Helps fit down on my commute and I often learn a lot.

During the hitchhiking F, you were talking about the curb your enthusiasm episode where Larry David picks up a sex worker.

So he can ride in the carpool lane to a Dodgers game. And I wanted to let you know something about that episode. Did you know this?

No, I thought this was amazing.

Yeah. That episode was actually used to help secure an alibi for a man, Juan Catalan, who is arrested for murder.

They filmed the episode during an actual Dodgers game and it just so happened that Juan and his family were sitting in the same section as Larry David.

When they were filming and Juan's lawyer used the raw footage from the episode to help exonerate him.

So they picked up this guy for murder.

And they proved him wrong thanks to this curb your enthusiasm footage. He was like he was at the Dodger game. He couldn't have done it.

God did not want Juan and Jail.

Amazing. There's a short documentary on Netflix called Longshot and it is truly one of the stories you can't believe is true.

Thanks for the years of entertainment. I love sharing the knowledge with you guys through Listener Mail.

Stay positive and keep testing negative. Dylan.

Awesome Dylan. You're a cool cat. We can tell. Thanks a lot for that great email. That was amazing and we will definitely go watch Longshot very soon.

Totally. If you want to get in touch with us like Dylan did, you can send us an email. Send it off to Stuff Podcast at iHeartRadio.com.

Stuff you should know is a production of iHeartRadio. For more podcasts, my heart radio, visit the iHeartRadio app. Apple podcasts are wherever you listen to your favorite shows.

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[실루리아기 가설(The Silurian Hypothesis): 고대 문명의 흔적을 찾아서]-[The Silurian Hypothesis]

📋 Summary

실루리아기 가설: 지구의 잊혀진 과거와 미래의 지질학적 흔적

1. 실루리아기 가설의 기원과 이름의 유래

2. 왜 증거를 찾기 어려운가: 지질학적 제약

3. 무엇을 찾아야 하는가: 테크노 화석(Techno-fossils)

4. 하이퍼서멀(Hyperthermal) 이벤트와 기후 변화

결론

🎯Key Sentences

📝Key Phrases

📖 Transcript

[실루리아기 가설(The Silurian Hypothesis): 고대 문명의 흔적을 찾아서]-[The Silurian Hypothesis]

📋 Summary

실루리아기 가설: 지구의 잊혀진 과거와 미래의 지질학적 흔적

1. 실루리아기 가설의 기원과 이름의 유래

2. 왜 증거를 찾기 어려운가: 지질학적 제약

3. 무엇을 찾아야 하는가: 테크노 화석(Techno-fossils)

4. 하이퍼서멀(Hyperthermal) 이벤트와 기후 변화

결론

ListenLeap으로 딥러닝 학습

🎯Key Sentences

📝Key Phrases

📖 Transcript

ListenLeap이 실제 문맥에서 학습하도록 이끌어줌