CHARLES BERGQUIST: This is “Science Friday.” I’m Charles Bergquist.

FLORA LICHTMAN: And I’m Flora Lichtman. Charles, I know you’re into space stuff.

CHARLES BERGQUIST: True.

FLORA LICHTMAN: Do you have an extraterrestrial bucket list? Like if you had James Webb Space Telescope eyes and were not constrained by the laws of space and time, is there an outer space place you’d go see?

CHARLES BERGQUIST: Yeah. You know, I’ve always been a sucker for the classic spiral galaxies like M51A, the whirlpool.

FLORA LICHTMAN: I am picturing a giant hot tub in the sky. Is that what it looks like?

CHARLES BERGQUIST: I mean it’s kind of your classic textbook definition picture of what a galaxy looks like, but it’s also this stunningly beautiful spiral of swirling stars up against pitch black space.

FLORA LICHTMAN: Ooh. That sounds like a good destination. And I wish we could go see it, your giant space Jacuzzi, but we can’t. But guess what. We might be able to hear it. Do you want to guess what it sounds like?

CHARLES BERGQUIST: So on the one hand, I know that, in space, no one can hear you scream. But on the other hand, I also somehow imagine all the gas, and dust, and stuff making kind of a wispy, wooshy kind of thing, kind of like a shoo.

FLORA LICHTMAN: Well, what if I told you it could sound something like this?

[ETHEREAL MUSIC]

That choral music sung by trapped ghosts is Whirlpool Galaxy M51A. Not literally. Like if you blasted off into space, you obviously wouldn’t hear this. This sound is made by scientists taking real data and sonifying it, turning that data into sound. My next guests have transformed data from galaxies, black holes, nebulas, supernovas, you name it, into sound. And they put it all together in a new album called Universal Harmonies.

Dr. Kimberly Arcand is a visualization scientist at NASA’s Chandra X-ray Observatory in Cambridge, Massachusetts. Dr. Matt Russo is an astrophysicist and musician at the University of Toronto. Both of you, welcome to “Science Friday.”

KIMBERLY ARCAND: Thanks so much. It’s great to be here.

MATT RUSSO: Thanks for having us.

FLORA LICHTMAN: Kim, why did you start turning space data into dulcet tunes? Where did where did this all begin?

KIMBERLY ARCAND: Well, for me, I have been working for NASA’s Chandra X-ray Observatory for about 25 years. And I spent the first few years of my career just figuring out how to process this invisible kind of light, X-ray light, into something we can see and then sort quickly realized after a few years that that’s leaving out a segment of the population. Sonification is just this idea of translating information into sound.

FLORA LICHTMAN: And this is part of NASA’s sonification program? Like why does NASA want to do this?

KIMBERLY ARCAND: Yeah. So for the most part, it was because we’re really trying to make sure our data is accessible. Right. There is this idea that when you’ve got all of this type of invisible light that you’re working with, whether it’s X-ray light or infrared light, we don’t have to only prioritize the visual. We can use other senses to be able to explore it, to be able to learn from it, to be able to enjoy it.

And so sonification, in particular, was a technique that I had learned about from a colleague Dr. Wanda Diaz. She’s an astronomer and computer scientist who is blind and uses sonification to be able to understand stars. And so I reached out to Matt and his colleague Andrew. And we started working on a project to take Chandra data and other data sets that we had to translate them into something we could hear and experience in a new way.

FLORA LICHTMAN: Matt, you’re a musician and an astrophysicist. Is there a connection between the two?

MATT RUSSO: There is. And we’re not the first to realize. This is an extremely old idea. It goes back over 2,000 years to people like Pythagoras. For centuries, it seemed almost obvious that there’d be some connection between the cyclical patterns in the universe and the cyclical patterns in music and, in particular, the harmony of both. And it turns out there is a lot of overlap because music and astronomy both have a lot to do with repeating cycles and listening or observing how those cycles interact with each other.

FLORA LICHTMAN: I want to understand this better, how these sonifications work. I mean we know space is a vacuum and sound can’t travel through it. So what are we hearing?

MATT RUSSO: So there’s many different ways to do sonification. In some cases, you can simply take light data that’s received, so for example how bright a star is over time, and convert that into a sound wave. But you can also take more artistic approaches and maybe convert the pixels in an image to different musical pitches to communicate that information through sound.

FLORA LICHTMAN: So we’re hearing maybe a translation of brightness or maybe a translation of actually pixels. Are any of your sonifications actual sound data that has been pitched into our hearing range?

MATT RUSSO: Yes. There’s one amazing example. And it’s our sonification of the Perseus galaxy cluster. And that was an image taken with X-rays. But the image itself shows ripples. They’re actual sound waves traveling through gas in space that are launched by a supermassive black hole. And because the sound waves are visible in the image, we can extract their shape and resynthesize them as a sound. That also involves changing the frequency of those sound waves by about seven or eight musical octaves.

FLORA LICHTMAN: That’s actually fewer octaves than I would have guessed.

MATT RUSSO: Actually, I misspoke. It’s actually seven or eight actual full piano lengths, so 56 or 57 full octaves. Is that closer to your expectation?

FLORA LICHTMAN: Yeah. I don’t even know. That’s probably still fewer than I would have thought.

MATT RUSSO: That’s quite a lot. Yeah. 57 octaves means you’re doubling the frequency 57 times. So that’s really an exponentially large change in frequency.

FLORA LICHTMAN: So let’s take a listen to the sonified Perseus cluster. So this is a huge collection of galaxies with a black hole right in its center.

[EERIE MUSIC]

This sounds exactly like what I’d imagine a black hole to sound like. Absolutely terrifying. What are we hearing?

MATT RUSSO: We’ve heard that a lot.

KIMBERLY ARCAND: Yeah. A lot of people have said that. We’ve heard people saying it sounds like a horror movie soundtrack or it’s like something Hans Zimmer would write if he was working on a tense piece of music. I think it really helps strike our imaginations. But this one’s really exciting because this is one of my favorite data sets of all time. The science result for this came back. It came out in 2003.

Some colleagues of mine, Dr. Andy Fabian and some of his colleagues, were working on a study of the Perseus cluster of galaxies where this supermassive black hole is just burping out into the hot gas, creating these pressure waves. And they did the math to be able to find out that that was the deepest note in the universe being created, this diva out there singing this incredibly deep song.

And so when we started this sonification project, I was very excited to work on this one because it already had a sound, if you will, those sound waves in the image that we can hear. And so for this one, being able to actually translate that or resynthesize it back up, was very, very exciting for me because this is a data set I’ve stared at for a long time. And so to be able to hear it, to actually hear that true sound, was just super cool.

FLORA LICHTMAN: One of my favorite space structures are the Pillars of Creation. It’s a classic, obviously. And we got some brand new pictures from James Webb last year of the pillars. They look like these giant yellow monstrous fingers that are reaching out through the heavens. Please correct me. I feel like I’m on the line with people who probably could describe it better.

KIMBERLY ARCAND: You’re definitely on the track. The way I like to think of the Pillars of Creation, they are tall, skinny columns of gas and dust. And inside those dusty columns are just beautiful little baby stars forming. What I like so much about this data set– it’s very iconic. So a lot of people have seen it, are familiar with it. And it’s just beautiful. But not everybody can access what that image looks like. So being able to take that data and combine it with Chandra data where you’re seeing slightly older stars around it, that combination of data, taking that and bringing it into something you can hear is really exciting.

FLORA LICHTMAN: Well, let’s hear some of it.

[MUSIC PLAYING]

OK. This is actually– it’s kind of creepy for a nursery.

[LAUGHING]

KIMBERLY ARCAND: Yeah. What’s interesting about this data set, these tall columns of gas and dust, I think the tallest one’s about four light years tall. And a light year is the distance that light travels in a year so about 10 trillion kilometers, so say about 40 trillion kilometers tall.

And when you’re looking at that in optical light or infrared light, you’re catching those beautiful structures. And all around it are those slightly older stars that are kind of like having these little temper tantrums, if you will, in X-ray light. And so as you’re scanning across from left to right, you’re capturing those beeps and bloops of those little temper tantrum stars. And then you’re also very clearly hearing those tall, thin structures. So that was sort of the idea with that one.

FLORA LICHTMAN: So what are the beeps and boops exactly?

MATT RUSSO: When you look at the image created with X-ray light showing all of those intense X-ray bright stars, it’s like a spattering of paint. There’s bright stars all over. And in this sonification, their brightness and their position controls the note you’re hearing. So every little beep and boop you hear is a star emitting intense X-rays. And the pitch of the note tells you where it is in the image. So if it’s towards the top of the image, it’s a higher pitch. And the volume tells you how bright or extended that object is.

FLORA LICHTMAN: OK. And so the kind of windy synthesizer sound is actually representing the pillar that I see in the picture.

KIMBERLY ARCAND: Correct. Yeah. It’s hard trying to capture that texture, if you will.

FLORA LICHTMAN: That’s so cool. I mean, can we learn anything scientifically by listening to the universe?

KIMBERLY ARCAND: Oh, absolutely. In astronomy, there’s I think a couple of really good reasons for sonification for research. One of those reasons would be studying time series data or things like variable stars. Variable stars I think are a great example because when you have a variable star, there’s something changing. Right. So you’re getting the shape of the light curve, if you will, that’s going to indicate different kinds of information, whether it’s the relative sizes of the stars, relative surface brightnesses, or whatnot. And being able to track all those changes by sound can be really helpful.

FLORA LICHTMAN: That’s so cool. Matt, are there some parts of the universe that are more rock and roll and other parts that are more elevator music-y?

KIMBERLY ARCAND: That’s great.

MATT RUSSO: There are. The clearest example is solar systems. And this is also one of the earliest connections between music and astronomy. It’s actually pretty straightforward to convert the motion of planets into musical rhythms and notes. And so when you do that, every solar system has its own beat and its own kind of harmony. So some are very pleasant and peaceful. And others are a little more tense and disjointed. So there’s everything up there.

FLORA LICHTMAN: What about our solar system? Where do we fall on the cheesy to cool spectrum?

MATT RUSSO: Well, that kind of depends on your aesthetics. Our solar system, it’s not very harmonious in a classical sense, a fixed repeating beat like some other solar systems. But it has its own charm.

FLORA LICHTMAN: I’m Flora Lichtman. This is “Science Friday” from WNYC Studios. I’m talking with scientists who turn space data into sound. You said the movements of planets can be converted to notes or rhythms. I’m trying to imagine just what that means exactly. Like our orbit is given a note, our orbit around the sun?

MATT RUSSO: Yeah. So when you hear a note with your ears, what you’re hearing is sound waves oscillating very, very fast. So it’s air molecules bouncing back and forth at a certain frequency. And so if you take the motion of the planets say in our solar system, and you imagine speeding everything up by many millions or billions of times, then each planet has its own frequency. It’s doing its cycle at its own rate. And so you can associate that with a certain frequency of sound. And you could see if the planets work together or against each other.

FLORA LICHTMAN: Matt, what does it mean to you as an astrophysicist to hear outer space?

MATT RUSSO: Yeah. Yeah. Sometimes I do. It’s always very exciting when you have a data set and you have some idea for how it’s going to turn out but you never really know until you design the algorithm, you write the code, and then you press Run and you just sit back and listen to what’s in that data. So that’s always a very exciting moment.

And as an astrophysicist but also as a musician, I just also find it very exciting that there are several connections between music and astronomy. There are real sound waves happening in space. They can’t travel to us because there’s too much of a vacuum. But there is gas in space. There are stars. There are dust clouds with gas. And sound can travel through those objects. So I find it interesting from that perspective, that it’s kind of breaking that common idea that there’s literally no sound in space and that’s not quite true. It’s just sound just has a hard time traveling through.

FLORA LICHTMAN: There is sound in space.

MATT RUSSO: Yeah. Wherever there’s something for it to travel through.

FLORA LICHTMAN: You heard it here first. I love that. I love that. Kim, what about you? I mean just on the sort of emotional level, does listening to space produce a different feeling than looking over an Excel worksheet?

KIMBERLY ARCAND: Oh, absolutely. I mean so I think the first time I’ve heard some of these pieces, again, I know the data really well. I’ve worked on this stuff for years. And so I know these pixels. And the very first time I heard the galactic center, it was one of the very first pieces that Matt and I worked on. And it was so moving to me because it’s a very dense and busy data set. There’s a lot going on.

There’s all of these different kinds of light, three different kinds of light. It’s sort of a downtown area of our Milky Way. It’s like the hustle and bustle of the New York Times Square kind of area right so there’s a lot happening, a lot of energy, a lot of activity. And I can stare at those pixels and I can understand it. But when I hear it, it just makes me think about different segments of the data in a different way.

Sound itself just has a sort of stickiness to it. Right. Music kind of sticks in our head. And we process sound and music differently. And so I’ve looked at that image that I created back in 2009 I think quite differently since hearing it. I’ve found things in the data that I never realized before. I’ve seen different sections of that image and process it in new ways. And I love that. I love that sound can make me think of a data set that I’ve known and loved for so long in a new way. I think it’s really exciting.

FLORA LICHTMAN: Yeah. Probably makes you have a different feeling about it, too, or adds to it.

KIMBERLY ARCAND: Oh, absolutely. It adds to it. Absolutely, it does.

FLORA LICHTMAN: Kim, part of the goal of this project was to create something that’s more accessible for blind and low vision people. Have you heard any feedback from people who have used the sonification? How have they impacted people?

KIMBERLY ARCAND: Yeah. So we’ve been working with people who are either blind or low vision on this project pretty much since day one. We’ve had people saying things like I didn’t know the universe was so beautiful or I didn’t know the universe could be so engaging. And I love that this project is able to bring the data that I get to swim in every day to more people.

FLORA LICHTMAN: Well, thank you both for joining me today.

MATT RUSSO: Thanks for having us.

KIMBERLY ARCAND: Thanks so much.

FLORA LICHTMAN: Dr. Kimberly Arcand is a visualization scientist at NASA’s Chandra X-ray Observatory based in Cambridge, Massachusetts. Dr. Matt Russo is an astrophysicist and musician at the University of Toronto. To listen to “Universal Harmonies,” go to sciencefriday.com/spacesounds.

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