The Darkest Dark

Summary

Radiolab Podcast Summary: "The Darkest Dark"

Radiolab, hosted by Lulu Miller and Latif Nasser, delves deep into the mysteries of darkness in the episode titled "The Darkest Dark", released on January 17, 2025. This episode explores the enigmatic world of ultra-black deep-sea fish through the investigative journey of biologist Sanka Johnson from Duke University. Combining scientific inquiry with profound philosophical insights, the episode unravels how certain creatures achieve the darkest hues on Earth and the broader implications of these findings.

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1. Introduction and Setting the Scene

Molly Webster, one of the hosts, sets the stage by sharing her experience of winter darkness, creating a personal connection to the episode's theme of darkness.

[03:17] Molly Webster: "We are in the middle of deep winter. The shortest day of the year just happened... it can feel like there's just nothing out there. There's nothing beyond it, there's nothing in it. It's just kind of this black void."

This introspection leads her to encounter Sanka Johnson, whose work redefines her understanding of darkness.

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2. Sanka Johnson’s Deep-Sea Expedition

Sanka Johnson narrates his experiences aboard a research vessel navigating the pitch-black depths of the ocean.

[02:17] Sanka Johnson: "When we're at sea, beyond the ship lights, it's absolutely dark... you feel like it's asking you something."

Describing life on the ship, he emphasizes the suffocating industrial environment dominated by steel and diesel fumes.

[04:48] Sanka Johnson: "You live in a very small room... a bit like an oil rig platform without the oil."

Despite the challenges, Sanka expresses a profound passion for being at sea, highlighting the unique and isolated life aboard.

---

3. The Mystery of Ultra-Black Fish

Sanka introduces the core mystery: capturing images of deep-sea creatures so black they elude photography.

[06:19] Sanka Johnson: "80 to 90% of the species down there can make light... but there was this group of animals that we simply could not get a good photograph because they were just so... incredibly black."

He describes how these fish resemble "the black holes of fishes," absorbing nearly all light, making them indistinguishable from their surroundings.

---

4. Scientific Investigation into Darkness

To understand the unprecedented blackness, Sanka and his team investigate beyond pigments to the very structures that create color.

a. Exploring Structural Coloration

They examine butterfly wings, notably the Brooks birdwing, discovering that microscopic structures, not just pigments, contribute to their color.

[18:07] Sanka Johnson: "It's like this weird little forest where photons go to die."

Using advanced microscopy, they uncover a "honeycomb array" of tiny structures that trap light, preventing its reflection and thus creating ultra-blackness.

b. Linking to Moon Regolith

Unexpectedly, the mathematics used to study the Moon's soil ("regolith") becomes instrumental in understanding the fish's dark coloration.

[25:07] Sanka Johnson: "It turns out the soil of the Moon... is not so different in terms of the shape and size and refractive indices and absorption of these black fish."

This cross-disciplinary approach allows them to simulate and confirm how light interacts with the fish's melanosomes—the microscopic structures containing melanin.

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5. Discoveries and Implications

The research reveals that the fish achieve their darkness through a precise arrangement of melanosomes, optimizing light absorption beyond what pigments alone can achieve.

[25:30] Sanka Johnson: "They were about three to four times as black right in the area where the bioluminescence was."

This discovery has significant implications for technology, inspiring engineers to develop materials like Vantablack, which absorb nearly all light.

[26:43] Sanka Johnson: "Engineers try to make little tic tacs... to make really dark materials. Solar cells are a really big deal because everyone's trying to optimize the amount of electricity you can get out."

However, despite understanding the mechanism, photographing these fish remains elusive, underscoring the effectiveness of their natural camouflage.

[27:22] Sanka Johnson: "We still can't photograph an anglerfish. We can't get a good picture."

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6. Philosophical Reflections on Darkness

Beyond the scientific exploration, the episode delves into the philosophical nature of darkness. Sanka challenges the notion of darkness as emptiness, portraying it instead as a presence rich with complexity.

[30:00] Sanka Johnson: "Blackness, at least in my experience, is not an emptiness, but has an incredible presence. It feels very rich, like, you know, like it's the ultimate substance."

Molly Webster synthesizes this by highlighting that darkness contains multitudes, suggesting that what feels like an emptiness is actually a profound and intricate realm.

[29:23] Molly Webster: "Whether you're talking about a fish or the looming gloom outside of your window, what feels like an emptiness... actually contains multitudes. And not just that it is a place where all the light falls inside of it. So in a way, the darkest thing is also the brightest."

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7. Corrections and Clarifications

In the concluding segments, Molly addresses factual clarifications, ensuring accuracy regarding species like dragonfish and fangtooth fish, and acknowledging advancements in ultra-black materials surpassing Vantablack.

[30:31] Molly Webster: "Dragonfish, in fact, are not the fish that have fangs that slide back into their skulls. That is the fangtooth fish..."

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Conclusion

"The Darkest Dark" weaves a narrative that traverses the abyssal depths of the ocean to the frontiers of material science, all while pondering the essence of darkness. Through Sanka Johnson's relentless quest to unveil the secrets of the blackest fish, Radiolab invites listeners to reconsider their perceptions of darkness—not as mere absence of light, but as a realm teeming with hidden complexities and profound presence.

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Notable Quotes:

• Molly Webster [03:17]: "There's just kind of this black void."

• Sanka Johnson [06:19]: "They're like the black holes of fishes."

• Sanka Johnson [18:07]: "It's like this weird little forest where photons go to die."

• Sanka Johnson [25:30]: "They were about three to four times as black right in the area where the bioluminescence was."

• Molly Webster [29:23]: "What feels like an emptiness... actually contains multitudes."

---

References:

For an in-depth exploration and to read more about ultra-black materials and deep-sea biodiversity, visit Radiolab's website.

Transcript

[Roman Mars]

WNYC Studios is supported by the podcast 99% invisible. Design is everywhere in our lives, perhaps most importantly in the places where we've just stopped noticing. 99% Invisible is a weekly exploration of the process and power of design and architecture. Host Roman Mars asks questions, why do we use the bleep sound to cover up inappropriate words on radio and tv? What's with mall culture? And how did the mall become a ubiquitous part of American life? And why are houseplants having a moment right now? 99% invisible will answer all that and more every Tuesday. Follow and listen to 99% invisible wherever you get your podcasts.

[Soren Wheeler]

Radiolab is brought to you by Progressive Insurance. Do you ever think about switching insurance companies to see if you could save some cash? Progressive makes it easy to see if you could save when you bundle your home and auto policies. Try [e-mail] Progressive Casualty Insurance Company and affiliates. Potential savings will vary. Not available in all states. Dates Radiolab is supported by the John Templeton foundation, funding interdisciplinary research and catalyzing conversations designed to inspire awe and wonder. Dive deeply into the wonders of the [e-mail].

[Molly Webster]

Hey, Soren here, the executive editor of Radiolab. Most of you probably already know that we launched a competition to name one of our Earth's corpses. Quasimoons. These little moon ish, but not exactly moon, like bits of rock that hang out around our planet. And we now have a winner. We got a bunch of names in. You all voted on them, and we picked one, which means that we, well, really most of you, if you submitted a name or even voted, have named a heavenly body. It's the first time anything like that has ever happened to me personally. But to see the winner, you can now go to radiolab.org check out the name, and sit in that strange, dreamy feeling that we all helped to name a celestial body. Thanks for listening, thanks for participating and enjoy the show.

[Sanka Johnson]

Wait, you're listening. Okay.

[Molly Webster]

All right.

[Annie McEwen]

Okay.

[Molly Webster]

All right.

[Annie McEwen]

You're listening to Radio Lab.

[Sanka Johnson]

Radio Lab from wnyc. So when we're at sea, beyond the ship lights, it's absolutely dark, especially if it's a cloudy night. I mean, it's as dark as anywhere you can get on the planet. If they turn out the lights on the ship. I mean, it's just astonishing, you know, when you're there in like complete darkness, it's a funny presence. It's hard to describe, but you do feel like you know it's there and it's like, I don't know, it sounds Weird. It's probably left over some terror of the dark we have. Who knows? But yeah, you feel like it's asking you something.

[Molly Webster]

Hey, it's Molly Webster, this is Radiolab. We are in the middle of deep winter. The shortest day of the year just happened. And you know, when the sun sets at 4:30, it can feel like a wall just kind of descends outside of my apartment. Just like an impenetrable wall of blackness. And it can feel like that there's just nothing out there. There's nothing beyond it, there's nothing in it. It's just kind of this black void. And this is a lovely annual spiral that I get to go down until this year when I bumped into the guy you just heard from. His name is Sanka Johnson, He's a biologist at Duke University. And he told me a story that has me reimagining darkness this winter. And so this episode is that story. And we're gonna start with Sanka out at sea on the back of a boat.

[Sanka Johnson]

I mean, I always like to say that everybody wants to go to sea once and maybe one out of a hundred ever wants to go again. Because, you know, seasickness and all those things are, you know, kind of real. But the people who want to go again, I mean, they really want it. You know, we just have this, this passion for being out there. And not just the ocean and not just, you know, the animals, but, but the life on the ship is like it own special sort of strange thing.

[Molly Webster]

How so?

[Sanka Johnson]

Well, everything is decided for you. I mean you don't get decide breakfast, you don't get to decide lunch or dinner. You live in a very small room. I mean one of my rooms was so small that the bottom half of my bed actually went into the wall and so I would crawl in and my upper part of my body was still in a room and the other half was like dug into the bowels of the wall of the ship. And yeah, extremely industrial. If you like trees or anything green or anything like that. It's just a pile of steel. A bit like an oil rig platform without the oil. But it's still got the smell. I mean it smells really well, it smells intensely of diesel because of that.

[Molly Webster]

Really?

[Sanka Johnson]

Well, that's how you move the ship, right? You know, there's this giant engine.

[Molly Webster]

I guess I just thought it like went somewhere else. I don't know, like it went off the back of the ship and didn't engulf you or something.

[Sanka Johnson]

No, it goes right through your head.

[Molly Webster]

Wow, you've really painted a Picture here.

[Sanka Johnson]

You know, my wife always says that we need to stop calling it a cruise because then it makes it sound like a pleasure cruise when it's really more like working in a sort of a factory of sort, you know, out in the middle of nowhere.

[Molly Webster]

And what Sanka's doing out there is releasing these giant nets off the back of the ship and the nets get lowered down deep, deep, deep, deep, deep into the sea. Like we're talking 10,000ft almost. And they're trying to capture these creatures that live in a world where light and dark play out a battle of life and death.

[Sanka Johnson]

It's pitch black. You won't see anything. And so 80 to 90% of the species down there can make light. They're running around with little flashlights under their eyes and shining them forwards to look for things. They're fishing with light. You know, they're using their own light and the light of others to basically find each other and most of the time try to eat each other every now and then, try to mate some of these animals. Their whole body is covered with lights. And so, you know, we're collecting these animals in one way or another and then we photograph them in a dish. And literally it usually takes about one to 200 shots to get a nice shot of a, of an animal. It's a very frustrating process. Love doing it. But there was this group of animals that we simply could not get a good photograph because they were just so, I mean, basically incredibly black. To the point which, you know, when you took a picture of them, all you saw was like a black shape in the middle of the picture.

[Molly Webster]

You're not seeing gills, you're not seeing fins, you're not seeing, you're just, yeah.

[Sanka Johnson]

You'Re just looking at what looks like a two dimensional cutout shape of a fish. Normally when you look at things and we take it for granted, even when we look at things that are quite black, we see the shape of it. Like, you know, one of the, weirdly enough, one of the darkest things in our lives is a new automobile tire. And when you look at a tire, I mean, it looks like a tire, Right? So this just, I mean, you really feel like when you look at some of these fish, you're looking through them into a hole, into absolute nothingness.

[Molly Webster]

Wow. Okay, so what are the certain fish or species?

[Sanka Johnson]

One are. They're called the dragonfish and they're sort of like the evil fish predators of the deep. They're kind of long and skinny and they're lit up with a few Lights on their bodies. And they tend to have pretty impressive teeth that are so long that they actually have slots in their forehead so that they can close their jaw without the teeth punching into their brain.

[Molly Webster]

They slide their teeth into their skull.

[Sanka Johnson]

Yeah. So when, you know, they shut their jaw, I mean, if they didn't do this, they would literally impale their own brain with their teeth.

[Molly Webster]

That is gonna be the best thing I hear all day.

[Sanka Johnson]

And the other group were the anglers that people saw in Finding Nemo, where they're hanging a little bioluminescent lure on basically a little stick over their face. And so if the angler isn't extremely dark, that bioluminescence lights up its body, which makes it not a very successful lure. So you imagine you're some poor little fish. You swim up to see this nice, tasty looking bioluminescent sphere, and then you see a pair of big eyes and a giant body and all this other kind of stuff leering back at you. You're probably gonna back off. And so anglerfish need to be really dark so that they avoid lighting themselves up.

[Molly Webster]

That's fascinating. So it's not even necessarily, sometimes, I think, really dark to blend in or something.

[Sanka Johnson]

Well, it is. Any light you make is gonna give you away. It's like you're surrounded by enemies and. And if you give anything away, they're all gonna come for you.

[Molly Webster]

Oh, my gosh. It's like that horror film, like the Quiet place.

[Sanka Johnson]

Yeah, it's exactly like that. It's like a very tense world because the fish is working incredibly hard not to be lit up by its own lure. I mean, once we measured it, two things about them really surprised us. Okay. One was they were the darkest things that had ever been measured on the planet.

[Molly Webster]

Oh, my gosh.

[Sanka Johnson]

Yeah. They're about 100 times darker than anything that you consider dark in your normal life. You know, like I said, you know, a new automobile tire is actually one of the darkest things you see. And then, you know, like, whatever, a black table or, you know, any of the black things in your life typically reflect, you know, a few percent of the light. And these were about 100 times better than that. Oh, they're black. Is the blackest known technological substance, which is this stuff called vantablack.

[Molly Webster]

Is the fish darker than vantablack?

[Sanka Johnson]

They're kind of equal. They're all.

[Molly Webster]

I'm totally jumping in here just to say for anyone who has not seen Vantablack, Sanka and I did some googling of it. It's like this essentially spray on black carbon that if you put it on a surface, it, like, disappears the thing that you paint it on, so it ends up looking like you're looking at a black hole.

[Sanka Johnson]

A friend of mine bought some of the vantablack. And the problem with the vantablack is the second you look at it, dust starts to fall on it. And so then the surface ends up being a lot more reflective than you want. And the only way to get it on is to sort of cook it on in this hot vacuum, which is not great for lots of things. And here these animals are absorbing nearly all the light, and they're still able to swim around. It's really rugged. It's really robust.

[Molly Webster]

Wow. Okay, so you're staring at the blackest black, and you're not like, all right, job well done. No, we've done it.

[Sanka Johnson]

No, no, no, not quite.

[Molly Webster]

What happens next?

[Sanka Johnson]

I mean, the other thing, yes, we sort of learned in the measurement was. And this kind of blew us away because, you know, people talk a lot about natural selection and evolution and how animals have a strong pressure to increase their ability to do something. And we noticed that even though across the entire spectrum, these animals are extraordinari blacker than just about anything that's ever been out there. They were about three to four times as black right in the area where the bioluminescence was, which showed you that even though they were just about perfect, natural selection was pushing them to be even more perfect. And it gave you an idea of just how ferocious the pressure is down there to be as good as you can be in this way, to camouflage yourself as well as you can. So we knew they were fighting really hard, and we wanted to know how they were doing it.

[Molly Webster]

Like, how do you create the blackest black?

[Sanka Johnson]

Yeah, exactly. You know, if they're fighting that hard to do it, they must be doing, you know, something pretty cool.

[Molly Webster]

The journey to discover that very cool thing takes Sonka from butterflies to the moon and completely shifts around my understanding of darkness. And that's all coming up after the break.

[Annie McEwen]

All right, here I am.

[Molly Webster]

Ready to.

[Annie McEwen]

Ready to do it. I'm ready to do it. Okay. My name is Annie McKeown, and I am a senior producer at this show, which basically just means that I, you know, spend many hours banging my head against, you know, the computer screen, but, you know, lovingly banging. I think the best part of my job is creating an immersive scene so you can, like, see it in your mind and feel it in your heart. And it doesn't even really matter what it is.

[Molly Webster]

You want to set the scene?

[Annie McEwen]

Okay, so where are you? Okay, let's just say I'm at a jazz club.

[Soren Wheeler]

Cool.

[Annie McEwen]

It could be what it would be like to talk to a Neanderthal at a bar or. Alright, so a black hole moving through the earth. This primordial black hole punches through the atmosphere like a tiny needle of gravity. Or this scientist who looks deep down into the ocean and sees this octopus. Mom's little babies that are her species and they see a baby here and a little baby there.

[Sanka Johnson]

Little octopuses crawling around.

[Annie McEwen]

Like when I. When I'm actually building something that I'm feeling and I'm kind of like flying through it, I actually kind of feel like wee wee. And I'm excited to share it with people because if it's done right, it's like I can take you by the hand and lead you into this like, magical world that surprises you and makes you feel things that maybe you didn't even know you could feel. And if a story can do that, then the world becomes this expansive place where, like, that's possible anywhere and all these, like, doors open up because you've heard the unexpected. Radiolab and the work we create is possible thanks to the generosity of our listeners. Your financial support allows us to explore, report and invest in stories nobody else can do. If you rely on Radiolab and the kind of work we create, the best way to support us is to become a Lab member. The Lab is our membership experience where for just a few bucks a month, you can access exclusive perks and benefits like bonus content, ad, free listening, our full archive, limited edition merch, and so much more. To become a Lab member and support radiolab, go to radiolab.org join and thank you.

[Soren Wheeler]

Radiolab is supported by Capital One Banking. With Capital One helps you keep more money in your wallet with no fees or minimums on checking accounts and no overdraft fees. Just ask the Capital One bank guy. It's pretty much all he talks about in a good way. He'd also tell you that Radiolab is his favorite podcast too. Oh really?

[Sanka Johnson]

Thanks.

[Soren Wheeler]

Capital One Bank Guy. What's in your wallet? Terms apply. See capitalone.com banker FDIC Radiolab is brought to you by Progressive Insurance. Do you ever find yourself playing the budgeting game? Well, with the name your price tool from Progressive, you can find options that fit your budget and potentially lower your bills. Try [e-mail], progressive Casualty Insurance Company and affiliates. Price and coverage match limited by state law not available in all states. Radiolab is supported by Rocket Money. Managing finances can feel complicated and time consuming, right? But it doesn't have to be. Rocket Money is a personal finance app that helps find and cancel your unwanted subscriptions, monitors your spending, and aims to help lower your bills so you can help grow your savings. See all of your subscriptions in one place. And for those you don't want anymore, Rocket Money can help you cancel them. Rocket Money's dashboard also gives you a clear view of your expenses across all of your accounts and can help you easily create a personalized budget with custom categories to help keep your spending on track. Whether your goal is to pay off credit card debt, put away money for a house, or just build your savings, Rocket Money makes it easy. Cancel your unwanted subscriptions and reach your financial goals faster with Rocket Money. Just go to RocketMoney.comRL today, that's RocketMoney.comRL.

[Molly Webster]

Hey, it's Molly Webster. This is Radiolab. We are talking to Sanka Johnson, who is finding himself staring at some incredibly black fish. They're like the black holes of fishes. And he's trying to figure out, he wants to figure out, how do they get this dark? The trick is he maybe sees one of them every two or three years. So in order to set off on his quest to figuring out how the fish get so black, he actually has to start by looking at another animal.

[Sanka Johnson]

So we wanted something that was easier to get, but nevertheless still quite black. And we had heard that maybe there were some butterflies, that parts of their wings were really black. And we thought, well, wow, we could work with that.

[Molly Webster]

Where did you hear that?

[Sanka Johnson]

Funny enough, a really amazing insect biologist who is interested in the color of butterfly wings, like, 50ft down the hall. And so he pulls out this beautiful butterfly called a Brooks birdwing that's mostly green, but parts of it around the green are extremely black.

[Molly Webster]

So then you're just like, how?

[Sanka Johnson]

Yeah, exactly. Because the first thing you might think is, well, if you want to make something really black, just keep adding more and more pigment. Like, if you want to put something really black on, like a painting or something, just keep adding more and more black paint. Turns out that doesn't work. So you can have a coffee table that is absolutely soaked with some sort of really black pigment, and it's still kind of shiny when you look at it in a lot of directions.

[Molly Webster]

And the fish, the fish were not shiny at all. Neither was the butterfly wing. Remember, it looked like that void. So Sanka and his grad student Stuck the wing under a microscope to try and figure out what was going on. And what they saw was not a void at all.

[Sanka Johnson]

Yeah, it was really cool. It was like this beautiful honeycomb array, like those Czech cereals, except it sort of went in all directions, and it was very, very small. So there's a whole bunch of little holes, and they had a really particular size, being about the size of a wavelength of light. And we got all excited about that, because once it gets through, it's like there's this undercarriage that's like this crazy pinball machine where the light just sort of bounces around, you know, sort of unhappily and can never find its way back out the hole. Like, if you fell through a hole in the ice and you're trying to swim around, and so your chance of actually getting back out of the ice is really low. So turns out, to make something really dark, you also have to mess with the structure of it. You have to kind of create a weird little forest where photons go to die. There's some things going on with pigments, but for the most part, it's just about how this butterfly wing is made at a microscopic level. And we really had that hammered in when Alex took some of this black and green part of the wing, and he did a certain kind of microscopy that requires that you first spray kind of like a gold coating on top of them.

[Molly Webster]

Okay.

[Sanka Johnson]

And normally that makes whatever you spray. Well, it looks kind of gold. It looks like it just got sprayed with metal, like, you know, like the Tin man and the wizard of Oz. And they were still black, and they were still green, so it didn't matter. You spray all this gold on it. And the really. Yeah, they were just perfectly black. Still perfectly. Which meant that even though we had covered up all the color, you know, all the pigment, but we left the structure. The structure alone was enough to keep the wing completely black.

[Molly Webster]

It's like. So you're really diving deep into actually what color is.

[Sanka Johnson]

Yes.

[Molly Webster]

It is a hard concept for my brain to think structure. It's really thinking about the physics of color. Right. Which you don't often think about. You just think, there is a color, There's a paint, There's a thing, and I put it on something, and it is that. But, like, the idea that it's that you could cover up the color and the structure could still make a color is.

[Sanka Johnson]

Yeah, yeah. It's like, what gives them their beautiful green color or blue color or whatever is actually when you look at them in a microscope, they're just a forest of funny little structures, really. And those little structures preferentially reflect certain kinds of light. And in the case of the black parts, they basically. They reflect nothing. But what we really wanted to do is get back to the fish because, you know, we really like the fish. And so, you know, at this point, we knew that they had to be doing something really special with their structure, and we wanted to know what that was. And we expected to see something kind of like what we saw in the butterflies.

[Molly Webster]

Like the honeycomb forest.

[Sanka Johnson]

Yeah, something like a honeycomb forest or like this, you know, this crazy pinball structure or something to suck up all light. And it wasn't what we saw at all. Instead, we saw this. Basically, it's. I mean, I don't know how many people still eat Tic Tacs, but, you know, imagine if you don't eat Tic Tacs.

[Molly Webster]

You're talking to a person that will still eat a Tic Tac.

[Sanka Johnson]

I love Tic Tacs. Or, you know, all perfect. You know, they're sort of shaped, you know, kind of like an oval.

[Molly Webster]

It's like mini mini pills.

[Sanka Johnson]

Mini, mini pills? Yeah, like tiny pills. Right. And they're all piled together, and that's pretty much what we saw. Which.

[Molly Webster]

Well, you saw that in the fish.

[Sanka Johnson]

In the fish inside the fish skin. And each one of those little tic tacs is something called a melanosome. It's like a little structure that holds melanin, the thing that makes many animals dark.

[Molly Webster]

Whoa, wait. Okay, so is a melanosome a cell or. It's something that's inside a cell.

[Sanka Johnson]

Something inside a cell. Typically inside a cell, it's pretty small, and it's shaped like a Tic Tac, and it absorbs light. And normally, when you're looking at an animal that's dark, there are a few of these melanosomes in each cell. But in this case, there was this massive proliferation of them. The fish, they just sort of went nuts and just started making tons and tons and tons of these things to the point where the whole inside of the skin of the fish was just this crammed together pile of melanosomes. And we knew that wasn't enough. Like I said before, having a lot of pigment isn't enough to make something really dark. You have to have the right structure to go with it. And we thought that was going to be really easy to figure out what's going on. I mean, this involved basically a bunch of math. The problem is it's not so hard to Understand how light interacts with a particle when it's all by itself. But it's really hard to understand what it's doing when it's all in a pile, okay. Because all the little things in the pile, they all interact with each other. It's like if you throw a rock into a pond, you get this beautiful expanding, circular front of waves. Now imagine you throw, like, 10,000 little pebbles into the pond. Then you get this really complicated mess. And that's what we were trying to figure out was the complicated mess. And I think I was looking for technical ways of solving that mess. And weirdly enough, I kept getting pulled back to people who were studying the full moon, which we did not expect at all.

[Molly Webster]

I just thought you were gonna be like, yeah. And then one day in October, we figured out the math problem.

[Sanka Johnson]

No, no, no.

[Molly Webster]

So when you would scientist Google, a whole bunch of tiny particles piled on top of each other light, you would get articles about the moon.

[Sanka Johnson]

Yes. And in the beginning, it kind of surprised me. I was like, why would I keep bringing it back to the moon?

[Molly Webster]

Yeah. Cause I think of the moon, and I think bright. I don't think black. So I wouldn't be like, I'm going to look at the Moon to solve this black problem.

[Sanka Johnson]

Turns out the soil of the Moon, the regolith, is not so different in terms of the shape and size and refractive indices and absorption of these black fish. And so the math that was developed for the Moon could be adapted to study what was going on in the fish.

[Molly Webster]

And so what did it tell you about the fish? Like, what?

[Sanka Johnson]

Basically what we did is we were able then, using that math, to run a million different simulations to basically see the size of the particles was sort of the perfect size for making the fish as black as possible. And then we found out that not only were the little tic tacs the right size, but they were actually pretty much exactly the right shape, which was really cool because that shape and size was very different from the melanosomes you see in all the other animals. And so these black fish were actually fine tuning the shape and size of these little things so that once the light got into this sort of gumball pile of these tic tacs, it would just scatter around forever. And every time it bounced into another melanosome, more of it would get sucked up, the light would more or less get lost. And it ended up having a lot of implications for engineers who wanted to build things like this to make really black things that they can use in cameras. And spectrometers and a ton of other equipment.

[Molly Webster]

Engineers have co opted this research.

[Sanka Johnson]

Yeah, we see papers on it. Lots of engineers try to make little tic tacs that they're spraying on different surfaces or incorporating different surfaces to make really dark materials. You know, solar cells are a really big deal because everyone's trying to optimize the amount of electricity you can get out of a solar cell. But then also a lot of the sort of the internal parts of things that we use involving light, you know, cameras and things of that sort. It turns out there are a surprising number of people who are interested in making light go away.

[Molly Webster]

So can you photograph an anglerfish now?

[Sanka Johnson]

No, we still can't do it. We can't get. But now we know why we can't get a good picture. I mean that was kind of it. I mean we were able to solve, come up with the answer about why we couldn't get a good picture and we could figure out how the animals could do it. And it helped us understand a little bit more about sort of the hide and seek game in the deep sea and how deadly serious it is that animals will go to these extreme, you know, sort of adaptations just to avoid being seen by like a little bioluminescent flashlight.

[Molly Webster]

So you just of all, like there's so many things you've done in your life and like one of them was you're just staring at the darkest color.

[Sanka Johnson]

Yeah.

[Molly Webster]

On the planet.

[Sanka Johnson]

Yeah. I mean one of the things our lab studies a lot are like things like coloration, iridescence, bioluminescence and all that kind of stuff. But one of the things we always ignored was, you know, these sort of non color things, like basically the absence of color, like being extremely black. And so it was a really neat new thing to look at. And it got us really excited when we could see, you know, something that made ecological sense, you know, in these animals having to hide. And something that just ended up with such a striking result.

[Molly Webster]

Yeah, yeah. It is so cool. You're in a world where you're probably lured to the lores and then you've been staring the whole time at the blackest black.

[Sanka Johnson]

Yeah, yeah. I mean, I always say that, you know, we're, you know, as humans we're attracted to certain things and we ignore the thing that actually matters. So like, for example, when we look at something red, we really focus on the fact that it's red. But biologically what's really happening is something is taking away all the blue and green and yellow light. And that's the actual part that matters. And so what we see is actually the opposite of what's really happening.

[Molly Webster]

What that means is that the darkness, whether you're talking about a fish or the looming gloom outside of your window, what feels like an emptiness. Sanka's saying that it actually contains multitudes. And not just that it is a place where all the light falls inside of it. So in a way, the darkest thing is also the brightest.

[Sanka Johnson]

Blackness, at least in my experience, is not an emptiness, but has an incredible presence. It feels very rich, like, you know, like it's the ultimate substance.

[Molly Webster]

This episode was reported by me, Molly Webster. It was produced by me, Rebecca Lacks and Pat Walters. It was edited by Pat Walters. It was fact checked by Natalie Middleton with mixing from Jeremy Bloom. We also featured music by Norwegian pianist Vettel Nara. Before we go, two fact clarifications. Dragonfish, in fact, are not the fish that have fangs that slide back into their skulls. That is the fangtooth fish. Fangtooth fish can also be ultra black. In fact, all of these fishes are some of the darkest things measured on the planet. But they are not the only dark things we've seen. Ultra black in insects and in birds. To read more about all of this, head on over to our website. And for all of you tech heads out there, you probably know that by now there are new man made substances that are actually darker than Vantablack. All of that'[e-mail] and that's it. I'm Ollie Webster, this is Radiolab and I'll see you out there in the dark. Does that sound creepy? Thanks for listening. Bye.

[Lemon]

Hey, I'm Lemon and I'm from Richmond, Indiana. And here are the staff credits. Radiolab was created by Jad Abumrad and is edited by Soren Wheeler. Lulu Miller and Latif Nasser are our co hosts. Dylan Keefe is our director of sound design. Our staff includes Simon Adler, Jeremy Bloom, Becca Bressler, W. Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhu Nyanan Sambandan, Matt Kielty, Rebecca Lacks, Annie McEwen, Alex Neeson, Sara Khari, Sarah Sandback, Anissa Vita, Arianne Wack, Pat Walters and Molly Webster. Our fact checkers are Diane Kelly, Emily Krieger and Natalie Middleton.

[Sanka Johnson]

Hi, my name is Tresa. I'm calling from Colchester in Essex, uk. Leadership support for Radiolab's science programming is provided by the Gordon and Betty Moore Foundation Science Sandbox Samantha Foundation Initiative and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

[Molly Webster]

Here's a.

[Roman Mars]

Way you can support WNYC in our centennial year. Donate your used car. We'll turn your old car into the news and conversation that we've been serving to the community for over 100 years. Many listeners have already donated their cars to WNYC. It's an easy way to support the station, and you'll get a tax deduction. Learn [e-mail] car WNYC Studios is supported by Carnegie hall, which presents pianist Bruce Liu in recital performing works by Tchaikovsky, Mendelssohn, Scriabin and Prokofiev's Piano Sonata no. 7. Jan. 24. Tickets and information@carnegie hall.org.