A strange signal from space
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This is Unexplainable or Not, the game show where we finally get some answers. This week, our guest is Julia Longoria. She's been working on a new Unexplainable series all about AI that's going to be coming out next week. And then after that, she's going to be joining the Unexplainable team permanently. Welcome, Julia. Thank you. I'm so happy to be here with you all. We are extremely excited as well.

How are you feeling about making your debut on solving some high-pressure, potentially unsolved mysteries? I am shaking in my boots. I'm terrified. We love to welcome people when they're as nervous as possible. So here's what we're doing. Unexplainable or Not is a game show where you have to guess what we know and what we don't. You're going to hear three scientific mysteries, and you're going to hear them from me,

from our supervising producer, Meredith Hodna. Hey there. And from our senior reporter, producer, Bird Pinkerton. Hello. Two of these mysteries are still unexplainable, but one of them has recently been figured out. After you hear all the mysteries, you're going to get a chance to guess which one you think scientists have actually explained.

And this week, in honor of you, we're doing a whole Julia-themed show. Oh my goodness. You've worked on some of our favorite shows out there from More Perfect to Rabbit Hole to Radiolab. It's honestly kind of crazy how many amazing shows you've worked on. Guys, thanks. And each of us is going to tell you a mystery related to one of those shows.

I am so intrigued by what that means. Like, I just don't know. I'm really excited to hear what the mysteries are. Let's just say don't get your hopes up on the connections. But first up, you're going to hear a mystery from Bird. Hello, Julia. Welcome to the show. Hi, Bird. So I love to overachieve. So I have actually hit two.

two of your past jobs. Oh my god. And that my mystery is set in the Atlantic. Also the name of a publication you worked for. Okay, now I'm getting how tangential we are. I love it. Okay. And it's also about holes like your past show Rabbit Hole. So these are extremely real connections.

But mostly this is just an excuse for me to do my favorite thing, which is to acknowledge that the ocean is full of mysteries that we are trying to understand. And so today I want to focus on an ocean riddle that was turned up by NOAA. That's the National Oceanic and Atmospheric Administration. Two A's. Yes, the NOAA. So in 2022...

A NOAA ship was sent out to explore a bunch of spots in the Atlantic, especially along the Mid-Atlantic Ridge. And in one of their dives, they spotted these weird holes on the ocean floor. So this is like 2,500 meters down. How far down? So this was 2,500 meters down, like 1.5 miles about. And like, they look almost...

They're a little over a centimeter wide, a few centimeters long, and they appear in a straight line, like a line of holes one after another, almost like a row of stitches. Yeah, it really looks like a kid playing in the sand, like doing like... Really deep underwater in the sand. A mile and a half under the Atlantic. They don't look...

unintentional, essentially. Yeah, they look very intentional, yeah. And it's not the first time that holes like these have been spotted. There were others seen back in 2004, also in the Atlantic. And the scientists who wrote a paper describing those holes noted that they look kind of similar to holes that they'd found in fossilized rock, which suggests, right, that they're probably not man-made if they're also in the fossil record. But then...

How are they made? I reached out to NOAA, and they sent me a statement that said, essentially, it could be some kind of process happening. So maybe there's some kind of tectonic activity in the area, releasing gas bubbles that come up to the surface and make these holes in some way. I feel like gas bubbles wouldn't make that, though. Yeah, it's like, they're so rectangular looking that I was kind of like,

skeptical as well. But they're also considering organisms that might do this, like maybe something's moving along the surface and making these. Or they've considered burrowing organisms because there are little mounds of sediments by the holes. So to kind of check all this out, one of the things that they did was to collect some environmental DNA from the site. So that's basically like DNA fragments that are just floating around and

And the idea there is to look at those DNA fragments and compare them, see if they match up with anything in our like vast catalog of basically like everything that we have seen before, essentially. And in the statement that they sent, this lab director named Dr. Alan Collins said the little DNA fragments they gathered near these holes did not match anything in their data sets.

There's just so much down at the bottom of the ocean that we have not cataloged yet, right? That we can't always use our catalogs to figure out what's going on. And so that sort of leaves us with this mystery of what are these holes? Where did they come from? It feels a little absurd to think that you can encounter something like this 20 years ago and then encounter it again later.

in 2022 and still not have clear answers. But maybe it feels so absurd because we do have clear answers. And this is not a testament to how very little we know about the ocean floor. And it is instead a mystery we have solved. So, Julia, what do you think? Do you think we might have solved this one or do you think this is an unsolved mystery?

I feel like we would have solved it. That is what my gut is saying. They are just holes. They are just holes. How hard could it be? Yeah. All right. Just remember the gut feeling when you start getting more mysteries later on. Yeah. Next up, Meredith has her own mystery for you. All right. Julia, hello. Meredith, hello. My mystery today is all about concrete, which...

Not a direct tie to your resume, but we'll get there. It'll all come around. I'm on the edge of my seat. I know. Fascinating stuff. So concrete is the most used building material in the world. We're pumping out billions and billions of tons of it every year for our buildings, our roads, our dams. Like concrete is basically the bedrock of modern life.

But there's a concrete mystery that stretches back thousands of years to the Roman Empire. Hmm.

Just like us, you know, Romans, they used their concrete to build their roads, their aqueducts, their cities, even their marketplaces. You got some experience with marketplace, right, Julia? Hey! Nice. And their temples, like the Pantheon, built 2,000 years ago, this huge, unreinforced concrete dome that you can still see today.

And that is exactly the point. That concrete is still there in the middle of Rome. And it's not just in beautifully preserved historical buildings. You can see this ancient concrete in seawalls, like submerged in saltwater, getting pounded by waves, the harshest conditions. And these walls are still standing thousands of years later. And we don't know why. Hmm.

Some scientists think it has to do with the chemistry of the Romans, like raw materials. There's this very special volcanic ash that came from one very specific seaside town that Romans shipped across the empire to make their concrete. Other researchers think that the durability of this Roman concrete came down to how they mixed all of their concrete ingredients together together.

Either way, it's extremely hard to figure out why this concrete lasts so long. Because all we have are like the surviving remains, like chemically altered by millennia of wear and tear and, you know, being exposed to the elements. It's also impossible to tell what was like purposeful engineering and what was just kind of like a lucky accident in material science. Yeah.

But one thing that we do know is that our modern concrete doesn't stand up nearly as well. That was going to be my question, like, what's the shelf life on concrete? Well, so I asked a professor of engineering at MIT, Admir Masic.

And he told me that modern concrete has a shelf life of 50 to 100 years, maybe 150 years, like if you're stretching it. Wait, we outlive concrete? Yeah. Or some concrete? Some concrete. Depending how long we live, right? Yeah.

Issue with like if you look at the Frank Lloyd Wright building that was supposed to be like a waterfall building or something and they want to preserve it, but it's like falling apart because so much of it is concrete. Oh, interesting. It's very tragic. Totally. And it's not just architectural marvels we're talking about here. Our modern concrete infrastructure is continually crumbling and needs to be replaced and repaired even as we're going on to build just like more and more and more out of our concrete infrastructure.

And this has a huge environmental toll. The production of concrete is responsible for, like, billions of tons of carbon released into the air, accounting for as much as, like, 8 or 9 percent of just all greenhouse gas emissions just from concrete. Wait, why is it so, like, it's just rock? Why is it so, or it's...

It's just little bits of concrete. It's concrete rock. What is concrete? But why does it emit so much CO2? So the process of taking limestone and making it become like this liquid rock of cement that then gets mixed into concrete.

You're basically like heating it up so much that you're stripping out carbon dioxide. It's like pound for pound. Got it. Every pound of cement made releases just about a pound of CO2 into the air. That's so inefficient. Yeah. So figuring out the secret of Roman concrete, what makes it so durable, what makes it last so long. Yeah.

could be the key of making our own long-lasting concrete, you know, that doesn't need to keep being replaced and dramatically cut the carbon cost of all of our infrastructure.

You know, you're really blowing my mind because I'm like how I didn't quite realize we were building our societies on like such shaky foundations. Yeah. Shaky and like super environmentally harmful. Yeah. Yeah. Like, why are we doing that? Yeah. Isn't there better stuff to use? I guess. I don't know. Yeah. Maybe they figured it out. So what do you think? Do you think we know why Roman concrete was so durable or do you think that's still an unsolved mystery?

I'm leaning toward it's an unsolved mystery, but I guess I just found out that we are building on Shakespeare Foundation, so maybe we aren't. But I'm like very highly impressionable. Well, just hold off till the third mystery. Yep. And this one is inspired by your time at Radiolab. Nice. Specifically, the radio part.

I want to tell you about something called the Wow Signal. So in Ohio, in the 70s, there was this telescope called Big Ear. It wasn't a normal telescope with lenses and mirrors. It was a radio telescope, which means it was essentially listening to

for radio waves. And it would kind of output the data that it got on these spreadsheets. And an astronomer was going over this data, and he noticed this really weird signal. There's no recording of it, but there is a printout of the data, which I can show you here. Wow. Wow. Someone just wrote...

Wow! Exclamation point. I assume that's not the signal. No, no, that's where the name comes from. The guy basically circled the signal, which was just this huge spike in energy. And he wrote, wow. So, wow signal. But the next time that patch of sky where the signal came from was analyzed, it was gone. And the signal was never recorded again.

a chance that like a bird fell on something and no one noticed well the thing is it wasn't just that this signal never happened again the signal was kind of inherently strange because it was just in one narrow frequency so essentially like one note on the keyboard and

Which means that it probably wasn't a natural signal from space because if it was any kind of supernova or a pulsar or just something that happens all the time in space, that would have sent all kinds of frequencies. And the frequency it was sent at happens to be the same frequency that hydrogen emits radio waves at.

which got people ultra excited because this is the frequency that a lot of astronomers and scientists think that aliens would probably choose to communicate with us because they would probably try to communicate on the most universal frequency, you know, most common element in the universe, hydrogen. Wow. And there is actually an international agreement that prohibits broadcasting on this frequency. Wow.

because it might interfere with signals coming from space. All of which is why the guy who found this signal a couple years ago, he said, quote, I'm convinced that the wow signal certainly has the potential of being the first signal from extraterrestrial intelligence.

Now, he might be biased. Yeah, we all want to be that guy. We all want to be the guy who discovers aliens, right? So I called up a different astronomer just to get her sense of things. She's a radio astronomer, so she also kind of specifically looks for radio waves coming from space. She works at the University of Oregon. Her name is Yvette Sendis. And she's not exactly convinced by the aliens theory, I guess.

I don't know if that's a shocker, but... I mean, I'm of the opinion that, like, if you think we're alone out here, you're delusional. I agree. But Yvette doesn't think this is the evidence that we're not alone. Fair. And she told me there's this theory that maybe a blast of radiation could have hit a hydrogen cloud in deep space, which would explain why this signal was just on the one hydrogen frequency. Yeah.

But no one's ever observed a radiation blast big enough to make the wow signal. So Yvette isn't into that either. She basically told me that it's easy to get excited about weird signals in radio astronomy. But given how many radio signals we're just always emitting all the time, if you detect something weird, odds are it's from us, like maybe a glitch on our end or something.

And that's basically what she thinks might explain this. She thinks it might have been a satellite or interference or something. But even that explanation isn't perfect because the wow signal wasn't moving relative to the stars in the background like a satellite would. It seemed like it came from somewhere really far away, which means that after all of this, we're left with a whole series of imperfect explanations that

Unless it was the aliens. And aliens, if you're listening, maybe reach back out and let us know that you're listening a little more clearly than just... Who dis? New phone. Yeah, maybe be a little more explicit than hydrogen. I don't know. So that's where we are. What do you think? Do you think we figured out the wow signal? I don't know. I'm on the fence about this one. Sounds like you're on the fence about a lot of them. Yeah.

Perfect. I knew I was going to be bad at this game. So you've got the mystery of birds' weird deep ocean holes. You've got Meredith's Roman concrete being way more durable than we would otherwise expect. And we've got what potentially caused the wow signal. They're all unexplainable. Or at least they all were unexplainable at one point.

One of these potential mysteries has recently been figured out. And you'll have a chance to guess after the break. Support for Unexplainable comes from NetSuite. In case you didn't know, crystal balls, not real, which means it's tough to predict the future. And that means it's pretty tough to run a business.

But with NetSuite by Oracle, you don't need a crystal ball. NetSuite says that almost 40,000 companies choose NetSuite to help future-proof their business so they can stay on track no matter what tomorrow brings. NetSuite's a top-rated cloud ERP, bringing accounting, financial management, inventory, and HR into one fluid platform.

NetSuite says they offer real-time insights and data that you can use to make the right decisions at the right time. NetSuite says they can help you respond to immediate challenges and seize opportunities. Speaking of opportunity, you can download the CFO's Guide to AI and Machine Learning at netsuite.com slash unexplainable. The guide is free to you at netsuite.com slash unexplainable. netsuite.com slash unexplainable.

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Ryan Reynolds here from Mint Mobile with a message for everyone paying big wireless way too much. Please, for the love of everything good in this world, stop. With Mint, you can get premium wireless for just $15 a month. Of course, if you enjoy overpaying, no judgments, but that's weird. Okay, one judgment.

Anyway, give it a try at mintmobile.com slash switch. Upfront payment of $45 for three-month plan, equivalent to $15 per month required. Intro rate first three months only, then full price plan options available. Taxes and fees extra. See full terms at mintmobile.com. It's nice to meet you. I'm Julia. It's unexplainable or not. Julia, welcome back. Happy to be here. We've got three mysteries to choose from, and only one of them has been explained.

Mystery one, what are all these weird holes at the bottom of the ocean? Mystery two, why was Roman concrete so strong? And mystery three, what's behind the wow signal? So just kind of tell me what you're thinking. Okay. Maybe all of your anxieties. I'm very anxious right now. Okay.

Just a baseline assumption I have is that the ocean is such a mystery to us. So I have a feeling that maybe we don't have an explanation for that one. And then as far as the concrete, it does feel like one that we would

most feasibly have an answer to. But it's the kind of thing we would like just postpone figuring out because like big concrete, you know? Big concrete doesn't want better concrete? Because then we wouldn't have to fix the concrete all the time. Like that's, you know, that's big money. It's all an elaborate ruse. It's a concrete conspiracy. It goes all the way up to the top. Uh,

And yeah, the last one, I mean, I'm puzzled by, but I feel like maybe it has a dumb answer. Like bird really like, I don't know if you were trying to sway me or to bamboozle me with that. Maybe a bird went on there. I am a bamboozler, famously. That's true. I had that feeling. I'm going to guess and probably be wrong that the last one, the wow, is the one that we know. Wow. Wow. Wow.

Wow signal, final answer? Wow signal, final answer. Okay. Locking it in. Here's your answer. Instead of degrading, it gets better. That's what is happening with Roman concrete.

They cracked open big concrete. They found the answer. Big concrete's got to worry. Now who's shaking in their boots? Julia, your face two seconds into that quote, it just fell. I know, you were just like, no! God damn it. So, Julia.

why Roman concrete is so durable has been figured out. And Meredith is going to tell you how this mystery was solved shockingly recently. Yeah, so it turns out that I, Meredith Hodnot, am the bamboozler.

It's always the ones you don't expect. I know. Underneath this smiley facade, it's just bamboozled down to the core. So we just heard from the MIT engineering professor I talked to, Admir Masic, and he just loves concrete. The beauty of concrete is...

is the fact that you have this incredible freedom of forms. You pour concrete and then it solidifies into a rock. He found out a couple years ago why Roman concrete lasts thousands of years. And he says it all has to do with the mix. So, little Concrete 101.

Concrete is a bunch of sand and gravel and rocks all held together by a glue made from processed limestone and clay called cement. Heard of it. And throughout his career, Admir has looked at samples of Roman concrete from across the Mediterranean, some samples even preserved at Pompeii.

And everywhere he looked, there were these little millimeter-scale nuggets of mostly calcium. Yeah, that's a great... I never used the little nugget term, but I think it describes it incredibly well. It's gold for us in the sense that these little nuggets...

are super calcium rich. It's like a, like a Dairy Queen blizzard that's not fully blizzed. It's like got the big pieces. Yeah. And Edmure says it was generally thought that these nuggets happened because the Romans were just not very good at mixing their concrete. The nuggets were considered bad material processing. But

all the Romans bad at mixing all of their concrete. Like these nuggets are everywhere. You put so much effort in this material design and then you don't mix it properly every single time. It's like, guys. And that gave Admir and his team an idea. I started to challenge this, that Romans consistently badly mix their concrete.

So, cement, the glue of concrete, needs water to solidify. It's an important part of the chemistry that turns the calcium of limestone and other chemicals like silicates into such a powerful binder.

Admir says that he's been able to prove that the way the Romans mixed their cement meant that not all of the calcium combined with the water. These chemical reactions of mixing the concrete would get so hot that some of the water evaporated, leaving these calcium nuggets behind.

Our modern concrete is much more uniform. - It's a milkshake. - Exactly. - In the modern, you have all homogeneously distributed calcium, very boring, like super mixed in, whereas ancient Roman concrete is like super heterogeneous. - So let's use our concretes to make some walls. Over time, tiny cracks start to form in the concrete and water starts to leak in.

In modern concrete, that's it. It's the beginning of the end. The water gets into the concrete and these cracks, it can freeze and thaw, making those cracks spread even further. The water could get all the way down to the metal rebar that is the structural support of the concrete structures. And then it starts eroding and rusting and beginning the whole crumbling process. Hmm.

But in ancient Roman concrete, that water leaks in, it hits one of these tiny calcium nuggets, that nugget dissolves, then recrystallizes and seals up the crack. So what makes Roman concrete magical is the chemistry behind healing process that's not taking place in modern concrete.

Fascinating. Roman concrete is literally healing itself. And Admir and his team aren't suggesting we make concrete the way Romans used to. There have been like a few engineering advances in the last couple of thousand years that are worth hanging on to. But this discovery is inspiring ideas for additives to help modern concrete heal itself. Wait, so why wouldn't we just

make concrete the way the Romans used to. Like if their concrete lasted for 2,000 years and our concrete lasts for like 100 years, why wouldn't we just... I also am confused by this. Make all the stuff with Roman concrete. Yeah. Right. So the Romans, they knew a lot of things, but they did not know how to make a concrete wall that was not like gigantically thick.

In ancient Roman structures, there is no reinforcement, no steel. And so they built the structures with huge walls, thick walls, and everything was very, very bulky. And then while they could make these beautiful domes,

It's actually really hard to make flat concrete surfaces without that structural support. So the top of the Pantheon is just like this open skylight. And Admir was saying like, yeah, that's probably because they kept falling down because they couldn't figure out how to structurally support it. Maybe they even tried to make it and were not successful and then just left it open. I don't know. I should actually look into that. So if we want to keep our like

thin-walled, elegant concrete skyscrapers with all those, like, real nice flat floors. We got to figure out how to take lessons from the Romans, but not do as they do. So, Julia, even though you didn't get the answer right here, you were stumped by big concrete, we do have a consolation prize for you, which is a song I wrote. Incredible.

Wow. Wow.

But finally scientists figured out why. It's because the Romans built them all with concrete. And tiny little hearts mixed clumps. They built them with concrete. These nuggets that were mostly made of calcium. They built them with concrete. It wasn't like they sucked at mixing. They built them with concrete. It's more like they just crushed at building. They built them with concrete.

These nuggets that we

The nuggets. Nugget really is an excellent word.

What a dream. One last thing before we go. Julia, the Unexplainable series, you've been working on Good Robot. It comes out next week. Yeah, it does. So I wonder if you could give us a little preview. I actually have a trailer for you. Okay. Let's listen.

Suppose in the future there is an artificial intelligence. I've been asking some very smart people a question that's been on a lot of our minds. Should we be worried about artificial intelligence?

But the answers I got from the greatest minds in AI surprised me. One guy told a parable of an AI that could cause an apocalypse. Let's give this super intelligent AI a simple goal. Produce paperclips. Be a paperclip? Be a paperclip?

Another woman cast AI as an octopus. We posit this octopus to be mischievous as well. And yet another story sounded like it was out of the Bible. She seems likely to drown. What should you do? Imagining AI as a savior. Like a god. Yeah, like a god. And all of these fantastical tales from the greatest minds in AI made me wonder, maybe even these people don't know what to think.

I'm Julia Longoria. Good Robot, a series about AI coming March 12th on Unexplainable, wherever you get podcasts. Oh man, I'm so excited for this, Julia. And we're so glad to have you on the team. Oh, thanks.

That's it for Unexplainable or Not. Thank you to our presenters, Bird Pinkerton. That's me. The Bamboozler. And Meredith Hodnot. That's my name. Both Bamboozlers. You said it. And thank you to our audience for joining us. If you have a mystery or a solved mystery you want us to tell on an upcoming game show, let us know. We read every single email. That's it for Unexplainable or Not. Goodbye.

This episode was reported by Bird Pinkerton, Meredith Hodnot, and me, Noam Hassenfeld. Production and music from me, editing from Meredith, who also runs the show. Production support from Thomas Liu, mixing and sound design from Christian Ayala, and fact checking from Melissa Hirsch and Anouk Douceau. Thanks so much to Julia Longoria for playing our game this week. Her unexplainable series, Good Robot, launches next week. And after that, you'll be hearing a lot more from her going forward.

So get excited. Thanks to Lauren Katz for her help with this episode and honestly all the game shows we've done so far. Thanks to Brian Resnick for co-creating the show. And special thanks to both Anouk and Rob Byers who are moving on to new projects. Anouk has been an incredibly thoughtful researcher and fact checker for us. And Rob has taught us all more about sound and engineering and just...

listening than I ever knew was possible.

If you have thoughts about the show, send us an email. We're at unexplainable at Vox.com. And you can leave us a review or a rating wherever you listen. It really helps us find new listeners. You can also support this show and all of Vox's journalism by joining our membership program today. You can go to Vox.com slash members to sign up. Unexplainable is part of the Vox Media Podcast Network. And we'll be back with the first episode of our series, Good Robot, next week.

And tiny little fun mixed cups These nuggets that were mostly made of calcium It wasn't like they sucked at mixing It's more like they just crushed and filled in And the nuggets, and the nuggets, and the no-nug-nuggets

All right, Sean, you can do this promo talking about all the great Vox Media podcasts that are going to be on stage live at South by Southwest this March. You just need a big idea to get people's attention, to help them, you know, keep them from hitting the skip button. I don't know. I'm going to throw it out to the group chat. Kara?

Do you have any ideas? In these challenging times, we're a group of mighty hosts who have banded together to fight disinformation by speaking truth to power, like the Avengers, but with more spandex. What do you think, Scott? I'm more of an X-Man fan myself. Call me Professor. Can I read minds? I can't really read minds, but I can empathize with anyone having a midlife crisis, which is essentially any tech leader. So

Minds are important, Scott, but we're more than that. I think that you can't really separate minds from feelings. And we need to talk about our emotions and explore the layers of our relationships with our partners, coworkers, our families, neighbors, and our adjacent communities. I just want to add a touch more. From sports and culture to tech and politics, Vox Media has an all-star lineup of podcasts that's great in your feeds, but even better live.

That's it. All-stars. Get your game on. Go play. Come see a bunch of Vox Media All-stars and also me at South by Southwest on the Vox Media podcast stage presented by Smartsheet and Intuit. March 8th through 10th in Austin, Texas. Go to voxmedia.com slash SXSW. You'll never know if you don't go. You'll never shine if you don't glow.