Planetary Radio: Space Exploration, Astronomy and Science - The Slime Mold and the Universe

Episode Date: April 8, 2020

How could a lowly slime mold help researchers understand the distribution of dark matter and galaxies across the cosmos? Joseph Burchett and Oskar Elek of the University of California Santa Cruz will tell us about their team’s groundbreaking work. Bruce Betts and Mat Kaplan announce the first live and interactive What's Up segment is coming on April 23rd. The guys provide their usual assortment of space oddities in this week’s regular segment. Learn and explore more at https://www.planetary.org/multimedia/planetary-radio/show/2020/0408-2020-slime-mold-universe.htmlSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The Slime Mold and the Universe, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. Our main story this week may blow you away. Actually, it should. We'll talk with two scientists who have used the feeding behavior of one of our planet's lowliest creatures to help model the distribution of dark matter and galaxies across the cosmos. It's a tribute to the benefits of multidisciplinary science.

Bruce Betts will also be along shortly with What's Up. Bruce and I have a big announcement, too. Here's a preview. You will be able to join us for the very first What's Up Live coming soon to a device near you. We don't have all the details yet, but it will definitely be on Thursday, April 23rd at 1 p.m. Pacific, 4 p.m. Eastern or 20 hundred hours, 8 p.m. UT. Just a little casual gathering as we all shelter in place and flatten that damn curve. And if you hear this in time, you can also be part of the very first virtual

Yuri's Night celebration on Saturday, April 11th. Yeah, the World Space Party is also going digital this year. You can learn more at yrisknight.net. Lastly, my terrific live conversation with NASA Chief Scientist Jim Green and astrobiologist Penny Boston about life on Mars is now available on demand. The easiest way to find it is from exploremars.org. Here's an even quicker-than-usual review of headlines from The Downlink, the Planetary Society's weekly gift of great resources to fuel your love of space.

NASA has begun a month-long celebration of the Hubble Space Telescope's 30th birthday. You can even find images it captured on your birthday. CHEOPS is ready to start revealing the diameters of worlds orbiting other stars. That's the European Space Agency's characterizing exoplanet satellite. And NASA has selected SpaceX for the delivery of cargo to the Gateway, that small maneuverable space station the agency plans to put in lunar orbit. As always, you'll find all the cool stuff in the downlink at planetary.org slash downlink and you can also sign up to have it delivered every Friday for free to your

inbox. Understanding the distribution of dark matter across the universe is one of the greatest challenges faced by astrophysicists and astronomers, surpassed, perhaps, by learning what the crazy stuff is in the first place. We can't see it, but its gravity appears to give shape and substance to the largest collections of regular matter in the cosmos, galactic clusters. Many theories and complex models have attempted to unravel what looks like a rat's nest of feathery filaments. We can probably assume that none of these efforts mean a thing to Physarum polycephalum. You may have seen it growing across decaying logs or leaves in a forest or even on your front lawn.

The spongy, bright yellow mass is just a slime mold. The spongy, bright yellow mass is just a slime mold. Nevertheless, the efficient way in which it seeks food has inspired a team of scientists. They have created an algorithm that may do a better job of modeling those filaments of dark matter than any previous attempt. The team includes scientists from the University of Massachusetts, North Carolina State University, and the Pontifical Catholic University of Valparaiso, Chile, along with several researchers at the University of California, Santa Cruz. That's where the two lead authors of the March 10 paper are. Joseph Burchett is a UCSC astronomer.

His colleague comes from a discipline that may surprise you. Oskar Elek is a computational media researcher in the university's creative coding lab. He has a background in computer animation. How these two young scientists came to realize that a slime mold could help us understand the universe is just part of what we covered in a recent conversation. Joe, Oskar, welcome to Planetary Radio. Congratulations on this work, which as soon as I got the press release, actually three press releases, I was just blown away. I am so glad to get you on the show to talk about this tie-in between a lowly

slime mold and the largest structures in the universe. Welcome to the show. Thank you. Happy to be here. Thank you, Matt. As Jeff Goldblum told us in Jurassic Park, life finds a way. I don't think he had this in mind, but are you as amazed as I am by the fact that this living creature was able to help us learn something about, I already said it, the biggest structures in the universe? Joe? something about, I already said it, the biggest structures in the universe. Joe? Absolutely. This is trying to characterize, map out the cosmic web in the universe on the largest scales using only the galaxies that we can go out and observe that should trace this cosmic web.

This has been a difficult problem that many people have approached in a lot of different ways. Each of these methods that people have employed to try to address this problem have their strengths and weaknesses. It's taken a lot of effort, and a lot of people, a lot of really smart, talented people have lent their energies toward this problem. And when we started out to try and study the cosmic web for our own purposes, I very much had in mind all of this work that had sort of come before and was about to default to any of these other established, more conventional methods. Given that all of this effort had come before, it was especially surprising to me that turning towards this algorithm inspired by the slime mold was really the best application for our purposes. told you that, and Oscar, I think I'm getting this right, that you suspected that the way this slime mold grows, the way it spreads across the surface looking for food, might be helpful with this challenge. Yeah, I think initially the similarity was kind of visual. So my history and my background is in computer graphics, looking at how we humans look at

things, how we see things, and how we can emulate that. And then, lo and behold, here we have this organism that looks very suspiciously like the cosmic web. Now, the organism is flat, it grows in 2D, by which I mean surfaces of things, dead trees, rocks, dirt, whatever. Yeah, flat land. dead trees, rocks, dirt, whatever. Yeah, flatland. Flatland, exactly. And the cosmic web is, you know, fully, beautifully 3D webbed network.

But it's kind of like the characteristic features that stood out. You know, when you actually look at it closer, and that's when we had already the hindsight of having done, you know, some months of work on this project, we saw this property of the transport network arise. That we realized is kind of the main link between these two. Oscar mentioned that the initial connection that he made was really a visual one, that the networks that the slime mold produces very much resemble the filamentary structure of the cosmic web.

Our initial sort of intent was to find a way to visualize the putative cosmic web, given our galaxy sample that we were working with for this project. I think even at the initial phase when we first, when Oscar brought this slime mold methodology to the table, at that phase, we were still thinking in terms of visualization. It was even another layer of surprise to me that that methodology could then carry through to actually doing quantitative analysis on the data. I want you to introduce us to this slime mold star. And I read, in fact, I saw the picture of it, and we will direct people from the episode page to this excellent UC Santa Cruz press release about this story, about this discovery by Tim Stevens up there at UC Santa Cruz. But first of all, I'm a product of the UC,

so I know the UC Santa Cruz mascot, which happens to be a bright... Yeah, tell me you didn't choose this mold because of the similarly colored UCSC mascot, the banana squad. I clearly did not choose it for that reason. We did not, actually. It's a complete coincidence. Anyway, if anybody who hasn't seen a banana slug, maybe we'll link to that as well. It is, I mean,

I'm a product of UC Irvine. We thought we were pretty cool when we chose the anteater as our mascot, but I'll tell you, the banana slug has us beat hands down. Tell us more about this slime mold and how it makes its way, makes its life on Earth. Yeah, Joe, go ahead. And then I'll provide mine. Just to set the stage for all of that, inspired by this sophisticated, almost intelligent behavior, the slime mold exhibits. You know, we've leveraged that to our particular astrophysical application. The slime mold is not an animal. It's not even a plant when we're thinking about the kingdoms, right, of organisms on earth. It's not an animal. It's not a plant. It's not even a fungus,

but it's a protist. So, you know, in terms of the hierarchical complexity of life, it's a very sort of simple unicellular organism. It's way down there, right? has a phase in its life cycle where the organism can essentially flourish. When it's flourishing, food is sort of abundant, say, in the damp, dark forest floor where bacteria are growing. And so food sources may exist in sort of disparate places, sources may exist in sort of disparate places, but the slime mold is able to establish a network, unicellular macroscopic organism is able to establish this network to sort of connect from food source to food source, you know, say across the surface of a log, you know, just across the ground, moving from place to place. And it's really sort of this phase of its life where it's active, where food is abundant and it can actually feed. It's kind of the phase of its life where its inspiration brings

about, it has sort of a filamentary structure and in turn this filamentary structure is what we use to map the cosmic web. I look at the slime mold from the position of just the patterns that it creates. Joe set the stage for the natural behavior of this thing. What it does from a computational perspective, it actually solves an optimization problem. So how do I relocate parts of my body to most efficiently cover as much space as possible? This is what actually makes the transport network sort of optimal.

Of course, there is nothing like perfect in nature. It's just that it's very close to what you would build if you wanted to most efficiently connect a bunch of spots on the map or a bunch of places in some higher dimensional space like galaxies. And so it's this structural or spatial intelligence of the organism that which we appreciated for and that actually helped us solve this problem. There was a bunch of obstruction necessary to happen for that. But in a sense, we are still connected to the original behavior. You're not actually using the growth of the actual slime mold. You've built its growth, the intelligence, if we can call it that, this what appears to be intelligent behavior,

but probably not intelligence the way we humans think of it, into the algorithm, which actually is the model that you've been able to use for this, I know. And I know also you weren't the first to notice that the slime mold, this network of filaments that it puts out might provide useful data and solutions, approaches for seemingly unrelated problems. I mean, I read something about the Tokyo train network that actually also seems to resemble this. Yeah, this is a perfect example because here you have this bunch of cities or districts of a city,

and you need to build efficient railway. Now, the railway has been built already, but the work that you're referring to is just showing that what are the similarities between the organism and the real world problems that we're solving. And again, we are looking at this not from the perspective of there are the same rules that guide building these networks. That's not the case. It's more like what are the overall properties or behavior after the fact? And then what can we find they have in common that we can use to kind of find

connections computationally? Joe, at first glance, you hear this and it just seems nuts. I mean, a slime mold's growth is not driven by the forces that form and arrange galaxies, right? I mean, that's kind of what Oscar's saying. Yeah, hence my skepticism at the very beginning. Right. A non-believer. Well, a true believer now. Oh, yeah.

Didn't art play a part in this discovery? Oh, yeah. The original connection was actually completely random. So I heard about Simul before, I'm pretty sure Jody before, but you know, we just didn't connect the dots. And then we saw work of this media artist, Sage Jensen, who's based in Berlin. This guy just created these beautiful animations, just using the base algorithm that we started with the work of Jeff Jones. He made it so beautifully stylized, even if just in black and white. The point is that you don't know what's underneath it on the first glance.

But the behavior, the patterns and structures that it creates are just irresistible. that it creates are just irresistible. And then when you look at the cosmic web, which I had the chance to look at just a month before because we discussed this problem with Joe, things just fell into place. So yeah, this has been very important. Joe Burchett and Oskar Elek of UC Santa Cruz will tell us more about the slime mold in the universe

in not much more than a minute. Planetary Radio is once again brought to you by the Caldwell Vineyard, creator of Rocket Science Wine. Sadly, we've finished our bottle of this great proprietary red, but the fun hasn't stopped. I've somewhat foolishly told a spacey friend of mine that I'll give him the distinctive empty with its more than fun back label. The entertaining and thought-provoking text on that little sticker was written by someone who calls herself Coombsville Ava. She was awarded a case of rocket science for her trouble. Think you're up to the same challenge? Caldwell wants your most creative work for their latest label writing competition. You've got till April 28th and up to 80 words to share the inspiration and enjoyment Rocket Science offers anyone who pours themselves

a glass. Enter as often as you like, become a finalist, and you too will be enjoying a case of Rocket Science displaying your own work. Get the lowdown at caldwellvineyard.com slash rocket science, C-A-L-D-W-E-L-L. That's caldwellvineyard.com slash rocket science. Good luck and happy landings. Back now to our conversation with Joe Burchett and Oscar Eelek. Joe, how did you begin to test this hypothesis? I know it involved this huge data set of galaxies. The original project, this is a Hubble Space Telescope archival data research program. This program is funded by the Space Telescope Science Institute to essentially look at the large-scale distribution of galaxies, which large-scale distribution of galaxies forms the cosmic web, right?

And to use the background quasars that shine through the cosmic web in the foreground, by studying the light of those background quasars, we're able to study the gas that comprises the cosmic web or that is a constituent of the cosmic web via its imprint on the background light. But essentially, the key data sets here, there's sort of two main data sets. One is from the Hubble Space Telescope, as I mentioned, but another is a sample of galaxies that were taken from the Sloan Digital Sky Survey. This is an enormous survey, millions of galaxies that are arranged over about a quarter of the night sky.

I had selected a small sample of these galaxies because if you essentially plot up, and this is true of any galaxy survey, if you just sort of plot up the locations of the galaxies, one can sort of intuit where the cosmic web structure should fall. Galaxies are apparently arranged in these sort of filaments, and they're seemingly empty spaces that are voids. This was sort of the initial application once Oscar went away for a weekend and he and his friend holed up and had their own little hackathon to do a lot of the work on this algorithm and sort of the key innovations that they added to it. So we initially fed it this sample of galaxies and the intuition, just what you see, as I said, when you plot up the locations of galaxies, where you kind of intuit the filaments should lie.

When Oscar employed his algorithm with this data set, what visually emerged was just such a striking match to that intuition. This was really an aha moment for me, and I erased 99% of my skepticism. But the scientist in me couldn't let go of all of it. And so the next step was to actually try to use this model in a situation where we sort of knew the ground truth about where the filaments existed and where the filaments formed in the universe. We employed a dark matter only cosmological simulation. So what that means is this is essentially an effort to put in the rules of cosmology as we know them, including the fact that the universe is dominated by dark matter, the universe expands. Using those just from those sort of some initial conditions, the rules of cosmology, let the universe evolve inside a computer until the times of today.

And then one can study how structure forms under the influence of gravity and dark matter. And so it's in those simulations where we know that the cosmological theory generically predicts, from simulation to simulation to simulation, generically predicts this cosmic web structure. So we used one of these simulations. Much of the effort in developing the particular one we used also took place here at UC Santa Cruz. Taking the locations of where galaxies are supposed to form in the simulation, we ran the slime mold-inspired algorithm on those locations locations and that gave us a prediction of where the cosmic web filaments should be according to according to the slime mold right but the nice

thing about using this dark matter simulation is unlike in the real universe where we don't know exactly where the dark matter is in the simulation you know where the dark matter is and so we can compare do a one-to-one comparison of the slime mold prediction of where dark matter filaments should be and where they actually were in the cosmological simulation. And we found an extremely tight correlation, particularly in the density regime where this project that I described before, this Hubble Space Telescope Archival Program, where we were really focusing our efforts and trying to learn more about the gaseous ecosystems of the cosmic web and where galaxies live. So it matched up pretty well. Oscar? Yeah. This match, I just wanted to emphasize that it's not because the slime mold somehow magically is the same thing as the cosmic web in the Dark Matter simulation.

It is by design that we managed to find this match. Which I'm saying just to not make the impression that this is some kind of black magic. It's really that the algorithm that we created is fitting to this data. This is a pretty standard procedure in machine learning and optimization where you have a data set, you're trying to approximate it

or estimate it with some kind of model, right? And in this case, the model is the abstracted behavior of the slime mold. The fact that we have this match is because we bent and configured and fiddled with the model until we got this really good match. And it's really just that it kind of learns the structure. So no need for a mystical connection here between slime molds and galactic clusters. Yeah, let's wait with that until the end when we talk about the implications of this. This is just computer science.

I hope that people will visit this press release. I said we will link to it from this week's show page at planetary.org slash radio because you will see all these great graphics that show the result of this computer modeling and show you where the galaxies are and then show you where the filaments are that connect them. And do I understand correctly, Joe, it's sort of at the intersection of these filaments where we tend to see galaxies forming. Yeah. In particular, the sort of largest structures, the most massive collections of galaxies,

really form at the intersections of these filaments, the so-called nodes. So these are galaxy clusters and galaxy superclusters form at these nodes. Galaxies actually form all through the filaments themselves as well, albeit at much lower densities. So if you think about the intersections of filaments themselves as well, albeit at much lower densities. So if you think about the intersections of filaments are really kind of the megalopolis huge cities of the universe. And lots of interesting things happen in the big city in terms of the galaxies and the gas that live in them. A big part of this study was to try to understand the connection between where galaxies live, whether they live in the New York cities and the Tokyos and the Bejings of the world, of the universe,

and the Tokyos and the Bejings of the world, of the universe, or whether they live out in the boondocks in say the Paintsville, Kentucky, where, where I grew up, tiny little town way out in the country, galaxies that live in relative isolation seem to have a tendency to form new stars. They, they, in one view, you could think of those galaxies living sort of longer, healthier lives in terms of it seems like they typically have young stars in them, which means they've had recent star formation.

Galaxies that live in the big city tend to be dead in the same view. I mean, they're no longer... They have a striking similarity to the society. Yeah, right, right. The metaphor works, yeah. But, you know, these galaxies haven't formed stars in a very long time. Just trying to understand that process

of why do galaxies out in the boondocks form stars profusely and those that are in the big city, what's happening? And we think that's related to the gas supply out of which galaxies form stars. That's sort of the impetus for thinking about galaxies from an ecosystem perspective and thinking about the gaseous environments and transfer that must take place. This formation of stars, I read that this was also another of, well, you called it apparently

another sanity check as you looked into this, because you looked for the formation of these newer stars and it helped increase your confidence? Yeah, absolutely. The picture that I just painted of galaxies in sparser environments having a greater tendency to be star forming than those that live in denser environments. This has been observed for decades now. So that's sort of a well-known result. And it's been refined through the decades, through the years, in terms of quantitatively assessing this relationship.

So yeah, so one of the sanity checks was, you know, the great thing about the product of this slime mold algorithm and running it on the data is we get a local density value for every point in our 3D space. We can go to the locations of the galaxies and we can, from the slime mold model, get its density, the density of its local neighborhood. And then we're able to look at the star formation activity of each galaxy and simply correlate the two. And we're able to recover this behavior that I was just referring to, the tendency of galaxies in denser environments of a fixed mass. If you go into a denser environment, the tendency for that galaxy to be red and dead, so to speak,

the tendency for that galaxy to be red and dead, so to speak, is indeed increased. I am no astrophysicist or cosmologist. I just make my living talking to people like you. But this would seem to indicate a fairly major advance in how we can learn more about our universe, about the cosmos, and where it is headed. about our universe, about the cosmos, and where it is headed, and perhaps a bit more of information about this mysterious stuff called dark matter. Yes, absolutely. This study has been just sort of associating the gas of the intergalactic medium on the largest scales with the cosmic web that's traced by galaxies. And that cosmic web structure is consistent with predictions from our dark matter dominated cosmology in terms of the matter in the universe. But yeah, there's great potential here.

And this is what I'm most excited about is where we could go from here. The ability of this model, of this methodology, to trace out the cosmic web structure, we have some real advantages here that I think some of the previously developed methods perhaps lack. It has maybe some weaknesses relative to those other previous models as well, but we're able to take large galaxy surveys and very efficiently. the simulation, the slime mold simulation runs in a matter of minutes, we're able to produce a prediction of the dark matter cosmic web structure in the universe from the galaxy data in that survey. You know, Joe mentioned this critical property that we get actually a density of the slime mold or of the cast estimate

in 3D space. Maybe members of the audience might be curious, how can we get a density, right? If you see a slime mold growing, it's kind of binary. Either it's there or it's not there, right? So this property comes, again, from the algorithm and the modifications that we had to do to it. Again, we're kind of one step away from the original context in the sense that we no longer simulate slime mold, but we take inspiration from its growth and then simulate a continuous structure that actually has density. And it can have gradients in space. It can have just full-on transitions. And this is actually what's beneficial for the application,

but it's also something that makes it more robust because you're not trying to make a distinction between something being there or something not being there. But now it's a matter of degree to which it is there. So it sounds like the human element in this was as important as the contribution of the slime mold. Well, I mean, it taught us a lot. And we are humble in accepting that something so simple

can be better than us in these aspects. But what I'm talking about is just the design that we added into it to solve our particular problem. To get back to what we can learn about dark matter, Oscar just described this ability of the methodology to give you sort of a local density in space or a probability of a filament being at this particular location. A lot of people are searching fervently for dark matter and signatures of dark matter. This method can provide sort of a signpost or can provide guidance as to where to look, right? You want to look at the very densest pockets of the universe to try to have the

greatest likelihood of detecting a dark matter signal, right? If there's more stuff over here rather than over there, you're more likely to detect it if you look in the denser pocket. I think there's a lot of potential to employ this method in those kinds of searches as well. Very exciting. Shifting gears very slightly, both of you embrace interdisciplinary approaches to science. It seems to me that we would not be having this conversation today if you didn't. Is this key to all of this? Oh, yeah, certainly. I began interfacing with the lab Oscar works in. Shortly after I arrived in Santa Cruz, I was, I was out at an open mic night.

I'm a guitar player, singer, songwriter, where I went out to share a few of my songs and another act featured Angus Forbes on drums. He runs the creative coding lab. We were just sort of chatting after both of our, our sets. And he mentioned that he was an assistant professor at UCSC and he was this expert in data visualization. He probably didn't phrase it exactly that way. He's a pretty humble guy. But yeah, so he mentioned that he's very interested in immersive representations of data and extending how humans interact with computers in terms of analyzing data. This data set from the project that we're working on here of all of these galaxies from the Sloan Digital Sky Survey immediately came to mind. And I'm like, I think I've got the data set for you,

you know, if you're interested in sort of dabbling in astronomy, astrophysics. So we started working on this visualization application, which we eventually published. And I can provide the link to that as well, if you would like. Sure. Yeah. So this is just a web-based sort of 3D representation of this data set, juxtaposed with the Hubble Space Telescope quasar observations that are the diagnostics, what we use to diagnose the gas that fills the cosmic web, right? talk, you know, between me over here in astrophysics and Angus over there in computational media, it was inspiring being around this group of people coming from a completely different perspective, but who really had fresh approaches to thinking about data and fresh approaches, even sort of philosophically, as evidenced by, right by the inspiration of art and data visualization. So yeah, I think this whole collaboration really epitomizes the power of when people

from totally different perspectives, but sort of complementary philosophies can collaborate and bring each other's strengths, but also sort of inspire each other in unique ways. Oscar, before you get into your own interdisciplinary leadings, there's one other thing I want to note, because Joe mentioned that he was a professional musician. I know you recorded albums, Joe, and that one of your bands was called the Mandelbrots. And Oscar, you're kind of a fractal guy, aren't you? was called The Mandelbrots. I did not know that. Oscar, you're kind of a fractal guy, aren't you?

Yeah, very much so, yeah. You just blew my mind. I didn't know that Joe had such a band. I know he had bands, but this he hit from me. He talked about finishing a set at this open mic night. You didn't know he was talking about The Mandelbrot set. Yeah, I played one of The Mandelbrot set. Yeah, I played one of Mandelbrot's biggest hits.

I mean, the guitar even kind of looks like the Mandelbrot, so there might be something there. Maybe. Maybe another project to look into. Well, musification of Mandelbrot set. Okay, check. So, yeah, it's honestly I've, you know, since the early days of my materials and just generally kind of the

paradigm to think about all this visual complexity that surrounds us we people build you know very orderly structures but where in nature do you get square houses you know or cubic houses or circular wheels you know this is extremely rare So nature copes with things by building structures on multiple levels. And that's why we get complex ecosystems, right? That's why we get all this, this amazing stuff that's on this planet and surrounding it. So this is just kind of the prelude. But to me, thinking about the cosmic web as a fractal was extremely intuitive because that's how I've been approaching things for at least a decade now. Coming to Angus's lab, the creative coding lab, the nature of this computational media research is that you involve the arts,

you involve the visual, the acoustic, the different modalities to think about things. Oftentimes, it's not as rigorous to approach things like that. But rigor is something that for me follows kind of an initial inspiration or inception. And in this case, the inspiration was just really this visual gut feeling when you look at these structures. And so, yeah, this has been really important. Speaking of the arts, I have to mention one other thing.

When I looked at this intergalactic network of filaments in that press release, I don't know if either of you is a Trekkie, a Star Trek fan. The audience knows that I am. There was once, if I remember correctly, in a Star Trek Voyager episode, a map, a computer-generated map of what was supposed to be the Borg transwarp network to carry the Borg very quickly around the Milky Way galaxy. And it reminds me of what I saw in the model that you guys have built. Is that crazy?

No. Like if I was a Borg, I would definitely build my network as an optimal transport network. Well, the Borg has assimilated the slime mold, I'm sure. Certainly. Or the along the way. Somewhere. Well, just remember, in the words of Captain Picard, resistance is never futile. And neither is interdisciplinary research, guys. There's a poor segue for you.

But this has been delightful. Thank you so much, not just for the conversation today, but for bringing these interdisciplinary interests to light and making them work for us as we attempt to understand all that surrounds us, including the structure of the universe itself. This is very exciting stuff, and I look forward to hearing how things continue to develop. It's been a very pleasant conversation. Thank you so much, Matt. Yeah, thank you, and we are looking forward to that as well. Trust me. UC Santa Cruz researchers Joe Burchett and Oskar Eelek lead authors of a March 10, 2020 paper in the Astrophysical Journal Letters titled,

Revealing the Dark Threads of the Cosmic Web. journal letters titled, Revealing the Dark Threads of the Cosmic Web. We've got lots of great related links on this week's episode page at planetary.org slash radio. I'll be right back with Bruce. Bill Nye the Planetary Guy here. You've heard Matt deliver highlights from The Downlink, our great space news digest. You told us you want more. Well, you've got it. The Downlink now includes cool space images and fascinating facts about the cosmos that you can share with your friends and family. Best of all, you can have the downlink delivered to your inbox each week for free. Planetary.org slash connect is where to go to learn more and sign up. That's planetary.org slash connect for the downlink.

We've reached the time for what's up on this edition of Planetary Radio. So I am joined by the chief scientist of the Planetary Society. That's Bruce Betts. And I want to amplify on that announcement I made at the top of this week's show that we will join each other once again, except for the very first time, really live, not just Planetary radio recorded live, but live, live, live and in person virtually on Thursday, the 23rd, Thursday, April 23rd, 1 p.m. Pacific, 4 p.m. Eastern, 20 hundred, 8 p.m. U.T. as you inform me, because you think in U.T. I think nowadays. I do. as you informed me, because you think in UT, I think, nowadays.

I do. Well, that's good for us. I didn't have to look it up. I guess we're going to call it What's Up Live. Sure. That's catchy. It's either that or Random Space Fact Live, which is where we started with this. But it'll be fun because you can interact with us directly,

at least through chat. Ask us questions. Make comments. Submit a poem. which is where we started with this. But it'll be fun because you can interact with us directly, at least through chat, ask us questions, make comments, submit a poem. Bruce will have all kinds of cool stuff for us to talk about. I'll just be along for the ride. That will be the key personality addition to the show, able to mock me when I can't answer a question. Yeah, as I so frequently do. Anyway, there'll be more about this next week. And of course, we'll have more details as well at planetary.org. And

I'm sure it'll be pushed out through all the planetary societies, social channels, until they realize what they've gotten themselves into, at least. We just need to at least do the show before that happens. So tune in. It'll be online. It'll be virtual. It'll be video and audio, and you'll be able to submit questions and comments. There'll be random space facts. There'll probably be trivia. It'll be all the joy that we give you every week, but live and mockable.

And longer. Yeah. What, are we shooting for about a half an hour? Yeah, I think that's what we're shooting for. We're going to try and do lots of these live events out of the Society. Long overdue, we're going to do them at least weekly, and Bruce and I get to kick off this series.

Thursday, Thursday, Thursday! April 23rd. Be there! Oh, yeah. We were going straight to the sky. In the morning east, we've got those three planets all lined up from upper right

to lower left. We've got super bright Jupiter and yellowish Saturn and then reddish Mars. Mars and Saturn similar in brightness, and Mars will be brightening and brightening and brightening through October at its opposition. And if you check it out on April 15th, the moon will join the planets as well. Venus is still super bright in the evening west and on April 26th, the moon will join Venus. Venus

is kind of careening upwards in the sky relative to Orion or is Orion careening down. In any case, it'll be above Orion in the sky in the coming week. So Comet Atlas, we talked about last week, could be a naked eye comet in May, or there are some hints that it's starting to break up, so it may not be. So as always with comets, we'll see. On to this week in space history, 1961, first human in space, Yuri Gagarin. In 1970, Apollo 13 launched for what turned out to be an exciting trip. And in 1981, the first launch of the space shuttle. Big virtual celebration, virtual Yuri's night, since we can't get together in person this time. It's coming up on, well, at least the main one, the consolidated one, I believe, is Saturday, April 11, if you hear this in time.

I'm sure it'll all be captured on video so that you can enjoy it after the fact and celebrate that passage of humanity into space, just as Max the dog is. That was actually Gracie. Oh, sorry the dog is. That was actually Gracie. Oh, sorry, Gracie. Good night, Gracie. We move on to random space. I guess they aren't impressed by your impression. Oh, they're not. Well, it's hard to bark words.

That's why dogs don't talk typically. So, Matt, speaking of isolation, Apollo astronauts at the moon were about 400,000 kilometers from everyone but themselves. Command module pilots who circled the moon alone were at times more than 3,550 kilometers away from any other human, the equivalent of being alone in LA and having the closest human be in Washington, DC. Quite a distinction. And I think it got the gentleman who represents the answer for the trivia question that you're about to take care of for us, resolve. It is not coincidental. All right, we move on to the trivia contest where we discuss this individual. I asked you who is the first person to do a deep

space EVA, so outside of low Earth orbit doing an extravehicular activity. And I fear I once again have been caught not being specific enough, but it all worked out. How do we do? I am happy to announce this because Joe Murray, Joseph Murray in New Jersey has been a faithful entrant for about six years, at least. He's finally won. Joe, you did it. And he says, although, and he thought it was Dave Scott, but what we've read is, and a lot of you have said that James Irwin sort of did a stand-up EVA, stood up in the hatch. But it was actually the honors for the first real deep space spacewalk, or EVA, extravehicular activity, go to his fellow crew person, Al Worden. Yes, indeed. Al Worden.

And I wanted to honor him. He just passed away two or three weeks ago. He was just a wonderful man. I will read what a listener, Robert Laporta in Connecticut said. He said he had the honor of meeting Colonel Worden three times, gentleman and a gentle person, special man in a very unique group of astronauts, those 24 brave men who went to the moon. All of them were men, of course. A terrific guy with a great sense of humor as well. Very lively. And I know this because I also got the chance to interview him for Planetary Radio.

And we'll share that link once again. It's a very enjoyable conversation. Yeah, that would be great. What Bruce was referring to about the confusion, a lot of you said Al Worden, but also hedged your bets by saying maybe Neil Armstrong, because that, of course, was a couple of years earlier with Apollo 11 on the moon. But that's not what you were looking for, right? No, but I probably would have accepted either since I was sloppy. Sorry. But random.org chose someone who did say Al Worden, which was my vision of floating in space between the moon and the earth and going outside your space capsule. That seems kind of wild.

Mel Powell in California. He's one of those who hedged his bets. He said, though, that he says, I'd say I'm starting to know how Bruce thinks, but that's just terrifying. Save yourself. I thought you'd like that. Joseph, you are going to win. Well, the honor is not dubious, but the prize may be. If you choose, Bruce and I will record a message for you, a personalized message.

You can use it as your outgoing message on your voicemail system if you'd like to do that. Or you can just, you know, maybe put it on your MP3 or Bluetooth alarm clock and wake up to us every morning. Or put it on a loudspeaker broadcasting throughout the neighborhood. The reason Al Worden went out was to get these film cassettes from the cameras in the service module of Apollo 15. They were big. As we heard from Ian Jackson in Germany, the biggest of these was 152 kilograms. Film cassette contained two kilometers of film, 1,650 photos, which actually sounds kind of low. Ian says, yeah, they don't make cameras like they used to.

It was Mark Dunning who said, yeah, what would it be now? A little tiny wire and an SD card? He could just yank on the wire, I guess, and pull it back into the capsule. They'd have Bluetooth, right? They'd have Bluetooth to the service module. They certainly wouldn't have giant canisters of film that you had to leave. No. Mark added, now more than ever, you guys are the high point of my week.

Parentheses, my version of, I love you, man. Oh, man, we love you, too. Finally, Gene Lewin, our poet laureate, has the week off. But Gene Lewin up in Washington gave us this. Once a man took a stroll from Earth so far away, opening Endeavor's door, his stroll, an EVA, retrieving a cassette of film, the reason for this peregrination, the first in deep space, one of three accomplished in this fashion. He holds a record that still exists in Guinness books today, one for the most isolated human over 2,000 miles away.

Al Worden is the astronaut who took this distant tramp. I would have mailed him a letter if I only had a stamp. Oh, nice work. Thank you, Gene. We're ready to go on. We're headed to X-15 pilots. I know you love the X-15. And which X-15, you may just know this, Matt, but don't say it. Which X-15 pilots later flew on NASA spacecraft missions? Go to planetary.org slash radio contest. Well, I sure know one of them, but I won't say who because you've asked me not to. Otherwise, I would have. You have this time.

You have until the 15th. That'd be what would have been tax day here in the United States, but we all know that that's been swallowed up by the pandemic for, and we get an extra three months. Wednesday, April 15 at 8 a.m. Pacific time. And if you were chosen by random.org and you've got the right answer, you also might get a little personalized message from Bruce and me that you can do with as you wish. That's it. All right, everybody, go out there, look up the night sky and think about what it would be like to be alone circling the moon. Thank you and good night. Well, I can only tell you that Al Wharton said he loved it.

He loved every moment of it. He loved the solitude as well and being further from any other human being than anybody else has ever been. And that's in the interview I did with him. Hey, I'll talk to you next week and also on the 23rd when we will hear from everybody else as well for whatever we will end up calling it. I'll say as a placeholder, what's up live for now. Thanks, Bruce. Cheese muffin live. What do you have one in your hand?

I bet. No, I don't, but I'm going to. That's Bruce Betts, the chief scientist for the Planetary Society who joins us every week here for what's up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its never sly members who want to understand the cosmos.

Sound like you? Join them at planetary.org slash membership. Mark Hilverda is our associate producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Be safe, everyone. Ad Astra!