About this episode
Get every episode summarized
Each time Astronomy Cast publishes, we email you a written briefing from the transcript — the topics, who appeared, and any specific claims, with the ad reads skipped.
Email me new episodesFree for 3 shows. No card needed.
Hosts & guests
Transcript ready
321 searchable segments. Every word is indexed and playable.
Full transcript
Astronomy Cast — Ep. 778: Dyson Swarms. Machine-transcribed; use the interactive transcript above to jump the player to any line.
Oh Astronomy cast episode 778, Dyson Swarms. Welcome to Astronomy cast for a weekly
episode. Yeah, yeah, I every now and then, like for me, two coffee, right? One coffee I'm going to get up, one coffee after I've sort of done a bunch of important work and deserve a reward. Exactly. A third coffee if the second coffee just like didn't do its desire to job, or I'm just feeling like I want to continue the sort of habit to the ritual, but my wife gives me this sort of stern look and she goes, that's your third coffee, isn't it? And you, you know, you're you're too and fro from the bathroom, you are having trouble getting to sleep at night, you are feeling a little jittery, you regret it every single time, and I'm like, shut up, let me drink my coffee. There will be no regrets, I refuse. I refuse to ever regret coffee, except for Turkish coffee, that often at least to regret. Apparently the new research which we can shortly ignore is that having a mixed drink coffee and tea actually gives you the greatest health outcome. So so now Carla has wisely said, hey, I'll make you some taking your
children's tea and like fancy tea, long this and much of that. And so she will go like, oh, mix a tea. And so I'll have a glass a couple of the tea and then that that hits all the same spots. So so that's that's the solution. Instead of the dreaded third coffee up your tea game. I need easier to clean tea filters. Right. That's a personal problem. Yeah. Yeah. She's got like a metal one that she puts in her for her tea pot. It works really well. So right, let's do our job. Freeman Dyson asked a fascinating question. What would it look like if a civilization was using all the energy coming from the star? And what form would this take? This introduced the concept of a Dyson sphere or more realistically a Dyson swarm surrounding a star. But if you're skeptical about the concept, you're in good company and we'll talk about it a second, but it's time for a break. And we're back. Okay. So I want to get this out of the way before we
continue this entire conversation, which is that Angel Collar, who is a wonderful science communicator and YouTuber recently posted video proposing that the whole idea of a Dyson swarm Dyson by Freeman Dyson was like joke. He was trolling people who were thinking about the idea of radio surveys as a way to search for extraterrestrial intelligences and saying like if you think you could do a radio survey, why don't you do an infrared survey? All these ideas are dumb. You're all idiots, but you know, I'm going to write a four-page paper and lampooning you and done. Fine, maybe, but there has been a legacy to this idea that has persisted and grown to this day. So so yes, we've watched the video. I have, I don't know if you have, but I've watched the video. And and then I went on to to watch some actual interviews with Dyson and Dyson does not refer to it
as being satire or anything like that. He did consider it as an aside to his actual research, just a fun little thing he did. And I mean, we've all done ludicrous calculations to see what the result was. I figured out human beings, but gotified will be 70 light years long because I could. Nice. Yeah, yeah. So these kinds of things are within our capacity. And he asked the question, what would happen if we surrounded a star with solar panels? And and it was an aside, it was not his primary research. It was one of these things where he was very chagrand, you could tell in the interview, that this became the thing he was known for. But that's not the same thing as doing satirical research. People do do satirical research. This is not it. Yes. And so, so I think this elicits an emotional response in people. Yeah. And I, you know, we should definitely
unpack this maybe at some point later on in the end. But I, I think it's, it's important as you listen to this episode that you put that part of your brain and just set it aside, we will address it. I promise you by the end, but I, but, but I think what's important is the to take this question and just kind of go like we're using more energy. What happens if we use more energy forever? What are thealfusion limits of that drive for us to use more energy? What does that look like? And you sort of reach a sort of a logical sort of in state. And then you say, could we see that? And then that gives you some interesting answers that that legitimate astronomers have been puzzling to the state. So let's kind of go back and and sort of look at the original paper. What was the idea or what was the question that Dyson was investigating? It was basically a what are the full consequences of surrounding a a star with solar panels that
that was the core idea? And, and is this a way to to solve power issues? What will this look like from the outside? And it's the what will it look like from the outside? Which is where things to me get particularly interesting because there's there's no there's no getting rid of heat readily in space. And this is one of those things that everyone who's like put data centers in space seems to be ignoring. We obey all the laws of thermodynamics in this house. So, so the the problem ends up being you you have a system where you're heating up you're heating up you're heating up it takes a vast quantity of material to build it and for what purpose. And then you also end up with gravitational instabilities and stuff like that. Yep. Yes. So, so this idea like we know that humanity's use of energy has been growing at an
exponential rate since humanity first arrived on the scene. Yeah. And that that rate can be, you know, it is a smooth exponential curve and it is grown and grown and grown and now we use I don't know how many like petawatts of power ludicrous amount of energy right now across the entire planet. And yet that growth continues and people always say, oh, we'll we will stop wanting to grow a use of power will surprise surprise now we have AI data centers now something energy is even more a require than it ever was like we've came up with new reasons to be able to use it. So, so I think that that you can that you can say maybe we'll want more energy in the future is a is a logically sound proposition to me. Yes. And that you can then say what if we wanted all of it that was available to us. What is the maximum amount of energy that we could harvest from our local environment. And as you said, Dyson said, what if you tried to extract
all the energy from your star. And the idea that we're all used to the idea that's been popularized so much in science fiction Star Trek has one of my favorite examples. Yes. Is is the solid Dyson sphere and and it turns out Dyson spheres are highly unstable. The star does a little bit of of coughing up CMEs and and your spheres just going to wiggle wobble and it's not great. Well, the the problem is that when you put something in orbit. Yeah. Then that thing is is able to maintain a sort of balanced state around the object that you're orbiting. If you try to make a rigid sphere, you are no longer in orbit. Your equator might be in orbit. You're just gravity is held there. Yeah, the poles are no longer in orbit. Yeah. And so this thing
now is no longer sort of held in this this equilibrium and just will start to drift around or the star will drift around inside of it and will crash into the side of the Dyson sphere. There is no way to make a rigid Dyson sphere and make it stable. You have to make as you as we sort of have put into the title, you have to make a Dyson swarm. Right. And and Dyson knew this immediately. Like he he sort of, you know, he called it Dyson sphere. He was thinking of satellites in orbit around the star. And Larry Nevin took it in his science fiction in the direction of well, what about a ring? Yes. And even the ring is not stable. No, no. So so you have to have discrete objects in motion forces balanced the centripetal versus gravitational. Right. Then you can go for billions of years. Right. Look at you. It's got moons. They've been ordering for billions of years. That is stable. Yes. No problem. Yes. Yeah. Now,
swarms are are something that that is suddenly feeling more and more realistic as we look at the increasing number of communications satellites going around and around our world. And as we look at plans for there, there's this new satellite company that is literally looking to beam sunlight into nighttime areas of our planet because they can. Well, I always say that we have already begun to build our Dyson swarm. Yes. So look at look at James Webb. Yes. Right. James Webb is orbiting the Sun. It's orbiting in a very specific orbit, but it's essentially orbiting the Sun. It's not really orbiting the Earth. Yeah. It is collecting solar power from the Sun that would have made it off into space. And it's doing work with it. In this case, doing astronomy and computation. Right. All of the other satellites that we have put into space that are orbiting the Sun, they are part of our Dyson swarm. We've already begun the construction of our Dyson swarm. Now, it is pathetic, but you can imagine this smooth growth over time as we launch more satellites.
They do more work. They we come up with uses for them. They continue to harvest energy for the Sun. That it will never feel like, you know, now we will begin the construction of our Dyson swarm. It'll just be, hey, look, we ran out of energy that we can harvest from the Sun. And I mean, the other side of that is like, if you look at the geostationary orbits, they have very well defined. You put them here. They have this spacing. We are filling up the spacing. We are making the spacing smaller. Things are never fully stable in geostationary because the moon has gravity and that, therefore, it likes to yank things around. And so there's a lot of work that goes into trying to keep things in a nice neat grid. And so this starts to put you in the situation of, well, that's just one band around the quater that we're already starting to fill and it's already unstable. Now, what are the consequences? And I think we should look at two
different cases. One is the case of, let's surround the Sun. And then the other is, let's surround the Earth with steerable satellites that can collect light and beam it to the surface of the planet, which is something that people are talking about doing. All right, we're going to talk about those in a second, but it's time for another wreck. And we're back. All right, well, let's start with, I want to start with your second idea first because it seems like a smaller, more feasible idea. Right. So there are two different problems that folks are looking to solve with a Dyson Swarm light around the planet Earth. And one is by sticking enough satellites around our planet, by which I mean, far more than what Starlink will ever accomplish, you start to do a significant dimming of the amount of sunlight reaching the planet Earth. And because of that,
you can potentially offset a climate change by changing sunlight incident on the planet. Don't do this. We don't understand the science well enough. That's just the path to chaos. But so, so I mean, you're specifically talking about a geoengineering concept where you are attempting to block sunlight falling on the Earth as a way to combat climate change, not as a solution to our ever growing need for energy. It's a twofold solution. So on one hand, big old solar panels, you can't see how much I'm holding my arms out, big old solar panels that are collecting light, collecting energy, and blocking that light energy from reaching the surface of the planet. The other side that is, you then solve the energy crisis by doing tight beam pulsing of that energy to the surface of the planet. This increasing the heat on the planet.
Well, so this is where it starts to get, huh, because the idea is, and I love the fact that they're always like wirelessly send the energy to the surface of the planet. It's just sort of like, all right, we're going to stress that word of all the things you're going to stress. Yeah. So the idea is, sunlight has a whole range of different temperatures. It's a black body radiation. It's incidence across a wide area. So now instead, we're going to block out a lot of that light. We're going to focus it down to a narrow beam. We're going to send it down to the energy collector that is ready to somehow receive it. This is like, we're sodium and stuff like that. It's really good at collecting energy. How we do this is one of those things that isn't a solved problem. Right, question mark. I mean, isn't that sort of like putting your farm
in a warehouse and then putting grow lights on the top of the roof of your farm and then hoping that you're going to get that that that turned out to be the right, the smart move. Yeah. And and not a greenhouse, a dark warehouse solar panels on top. Grow lights on the other side. Now you're down to whatever is the efficiency of the grow lights. You are throwing away usable energy. And that energy that's going to be transported through our atmosphere has a number of different issues going for it. One of those issues is you don't want to fly a plane through it. So now you're having to keep track of all of these beams of light coming down from the sky to the surface of the planet. Yeah. Your satellites, you're not going to want to have them in geostationary orbits. So you're going to have to be essentially doing bursts of directed energy as as the energy is sent down to the collection areas. You can't do continuous blast
unless you have like a line of collectors around the planet. That's going to be hot. It's going to be when you're putting energy through the atmosphere. I mean, they're not saying the word laser necessarily, but what they're describing is narrow beam, columnized light. It's going to be hot. So now you're causing chemical reactions by heating up a a channel of air through the atmosphere in ways that normally it would only get heated through other things like lightning and stuff. It's not going to be as hot as lightning. But the collection systems are going to heat up. The computers are using this electricity for are going to heat up. They're going to release heat like can we just agree that you get one or the other? Yeah. That you either get to darken you get to reduce the amount of incident light falling on your planet or you set up collecting systems that are that are beaming power to the planet and you maybe get that advantage. You're going to get additional heat and you're going to heat the planet up. You have to kind of choose when you want.
And it's also a stability issue. When you look at graphics of what Dyson Swarms look like, they're always a sphere of equally spaced satellites. But the problem is that to stay in orbit, you have to be going round and round the world and the entire swarm can't be moving in lock, step like a solid object. And so you're going to have to have them at different altitudes. You're going to have them at different angles. And suddenly it starts to become a nightmare of traffic congestion. And you now have things at different altitudes that are beaming energy and potentially not just going to blast airplanes, but are going to blast each other. Right. So you know, we are skeptical. Yes. Okay. I want to move on to the actual, the Dyson Swarmist as thought through by Dyson, but it's time for another break. And we're back. So, so where do you get the stuff
to make a swarm that could completely surround your star? You take apart the entire solar system. Right. And admittedly, if you're doing a low key, very open swarm, you need less materials. So maybe you get to leave behind the planet earth. But what they've figured out, there's some really cool computations. And there's an excellent article in universe today where if you put one of these too close to the sun, there's just no thermodynamics controlling it. If you put it further out, that energy then has to pass over the planet earth. And so what they're talking about is if you put one out at like Mars-like distances, that's a good distance for it to work. But then you're going to raise the temperature of the planet earth. Yes. 140 degrees Kelvin or Celsius pick which one you want. Yes. 140 degrees is a lot people. It's a lot. Yeah. Yeah. The, if I remember this article,
you had to go to past Uranus, where the increase in temperature was only say four or five degrees. And like you're not, you're not going to have enough material to make a sphere that that's that big. Right. So earth is kind of going to the woodchip or two, right? Like if you want to properly build your Dyson Swarm and you want temperatures to be habitable, the temperatures have to be habitable on the satellites themselves. Right. There are no planets anymore. You are, you're doing that. Now you couldn't come up with a, with a way that maybe the earth is orbiting just outside the Dyson Swarm that the, that the orbits are overlapping in a way that leaves a gap open for planet earth as earth is rotating. Like I'm sure some future solar system engineer can come up with a architecture that allows you to have a planet. Still get that sunlight while you have the, you've dismantled everything else and you just have the rest of the Dyson Swarm. For, you know, because you're, you're nostalgic about the planet that you grew up on. It's an easy way to have the correct amount of gravity. Right. Yeah. Sure. But I, you know, at this point,
you've got probably rotating space stations that are thousands of kilometers across. Right. Like you've, you've got to, you've come up with, you, you've, you've dismantled your, your planet. So how much energy like, like what do you get out of this if you go into dismantle your solar system? I mean, you can nominally capture 100% of the energy coming off of the sun. So the total energy coming off the sun is 10 to the 33 ergs, which admittedly is a stupid astronomical unit. Normal people speak in watts. So this is 10 to the 26 watts of energy. That's a lot of zeros. Yeah. So, so I don't think there's enough light bulbs that have ever been created to take advantage of that. No. I now want to do the calculation of if you made a light bulb every second since the beginning of the universe, do you get there probably,
probably. Right. But yeah. Yeah. Yeah. It's a lot of energy. And, you know, people always go, like, no one's going to need to use that much energy. And, and my response is humanity says, hold my beer. That, that we will invent reasons to use all of that energy. Ideas that we cannot even fathom or imagine today. You're moving the solar system around. Yeah. You may want to move the solar system. You may want to park it into a better orbit. There's all kinds of things, computation, running ancestors simulations, solving scientific problems. Who knows, you know, turning energy into matter in useful functions. Running a simulation of the entire universe, including all of the human beings in it. Yeah. Yeah. So we have no idea what they will use it. But I think it's, I think again, it is a reasonable assumption to make to say, I don't know what they're going to use it for, but they'll figure out a reason. And so now we're just going to try and calculate this thing. And so as you mentioned, downside is you probably don't get to have planets anymore.
That you're going to either super cook anything that is inside the orbit. And so you're going to have to, and you need the raw material, you are going to lose your solar system, the benefit you get is this Dyson swarm. So then I think the question is, and I think what Dyson was getting at it was, could we see this happen? Could we see them out there in the universe? What would they look like? And why? And this is where you take metal, you heat it up. It re-radiates in infrared. And so if you start looking for systems that are giving off vast amounts of energy in the infrared, because you've taken the energy that's coming through the surface of a star, spread it out over a significantly large surface area. And then the other side is just like a swarm may not be having to re-radiate the entire energy of a star. In one way or another, but it's still going to heat up. Data centers are still going to heat
up. Things that use power are always going to have heat waste. That's just one of the unfortunate realities of thermodynamics. There's heat waste. And so when we go looking at stars, we go looking for thermodynamic access in the infrared. And there is an interesting case, tabby star, where they were seeing really weird dips in the light curve. It was behaving in weird ways. There was this brief moment in time where we had to ask the question, is this a Dyson sphere under construction? The answer was no. No, it's not. Yeah, it's dust. And we could tell because the thermal access didn't match what you would expect from a advanced civilization engineering, it's solar system. But is it like just a cloud of dust around a star, just a kind of Dyson swarm, just an unintentional Dyson swarm? It's going to have less of a cliff
on its infrared radiation. So yeah. So this is an example of one that people are like, oh, maybe it's an alien megastructure. But there have been others. There was some research that was done within the last two years or so, where someone had noticed some candidate, potential objects that fit this criteria, where it's a compact object that is giving off, that is located within the Milky Way that is giving off an excess of infrared radiation and not other wavelengths. And then the applause blocks when H is in fact, they're not within the Milky Way, they are actually galaxies that are far away that are producing an excess of infrared because they have a supermassive black hole at the heart of them. And it's really hard to tell what is in the Milky Way and what is one of these galaxies and they've all lined up. And so you can sort of easily explain the way. But people have gone looking for and doing surveys of the universe to look
for these Dyson swarms. The wise data set was looked through to see what could be found. I'm sure the Roman data set is going to be looked through. Yes. I don't know if Euclid goes far enough into the infrared to allow it. That's I think so too. So Euclid's already starting to do data releases. This is one of those things where there's lots of different ways that people are asking are their civilizations out there. And this is one of the straightforward techno signature ways to go looking. And so I think I want to bring this back which is that sort of that idea that we talked about early on that you're feeling kind of skeptical about this thing. And my position is always that this is a thought experiment. Yes. That that you're asking yourself what if you take what if you continue on this growth curve? What if you do this? Does this create a signal? It does this give us a way to search for life in the universe. And it does. Yeah. It says
that if if civilizations proceed upon this course, then they're going to create these objects. They're going to have infrared signature. And we're already searching the universe for infrared signature. So why not take a moment, look through your data, see if there is someone usual infrared objects. If there are, maybe you're going to discover something new which people already have like Boyage and Star or these weird red galaxies. And and this is also one of those things where even if the idea of a Dyson swarm spelled out in terms of a a mesh network of satellites all at a given distance from their star working as a single entity. I mean, it doesn't have to be something like that. As I already said, something like that starts to become a traffic nightmare. But if instead you imagine a solar system where you have massive stations around it, I just finished rereading the children of time and then the sequel books which
include a solar system where one of the planets gets murdered for lack of a better way to describe what happens to the planet. And the entities, I'm trying desperately not to spoil the book. The entities all end up living in spacecraft. And so now you have a solar system that is swarming with spacecraft. They're trying to be the thing that keeps the civilization going. And so now you don't have a swarm, but you do have that excess of spacecraft that have excessive infrared radiation again. Yes, you don't have to go full Dyson swarm. You can go partial. You can just build an excess of spacecraft and that will start transitioning the star from purely the spectrum that you normally expect to see into something that is showing off an excess infrared radiation. And it is something that is detectable and something is within reach. And so I think if you hold in your mind the opinion that answering the question of whether or not we are alone in the universe is one of
the most important questions that humanity can ask has ever asked. And you would like to know the answer to that question. If I gave you an envelope and in that envelope was the answer to the question and you would question, are you curious, would you open the envelope, would you look inside, would you find out what the answer is, then we should always be looking for ways to conduct that search. Ways that may seem like crazy science fiction, but they are possible and they are feasible and we might as well just look. And this is one of those amazing cases where the same data that's needed to go looking for potential infrared excesses around stars will also do amazing science. So there's no downside to this one. Collect the survey data, allow us to do the research for all the different things that can answer from are there license fears to are there's red galaxies at the beginning of the universe, dust or are they red and dead? Let's check all of them out.
Yeah, and I think it's the same conversation where people like we shouldn't be looking for life on Mars, right? Like why not? Wouldn't it be cool if we did? Like let's not come up with the wrong answer to whether or not there's life on Mars. Let's come up with the right answer and the right answer requires discipline and caution and care and takes multiple steps and you need to make sure you do every piece of it correctly so that you can get a scientific consensus agreeing that each step has been done properly. Let's do the same thing with all of these other deep questions to try to get good answers. And that is the way we progress as a civilization and that is what I hope with this as well. There's a there's a you know there are have been about like 40 ideas proposed for how we could search for alien civilizations. Looking for the effects of nuclear wars, looking for the effects of you know them sending messages in our direction, them communicating with each other, them building megastructures that are blocking the light of the star, them visiting us, them setting up factories in the solution. Like there's a million there's there are dozens of ideas
that each one could be its own research project and I think a lot of them are kind of interested in the exciting and have other possible things we should search for. So you know are we absolutely destined to become a civilization that has a distance where no of course not right. Is it the only way that civilization progress of course not but it is something we could look for and it would be a fascinating and interesting we actually did find it kind of terrifying. Oh yes, oh yes and and this is this is the science of today where we could discover any of this in our lifetime or not. Yeah and that's that's why we keep looking as we don't know what we will or won't find tomorrow. Yeah yeah all right thanks Pamela. Thank you Fraser and thank you to everyone out there on Patreon who has supported us. This week we would like to thank the following $10 a month and up patrons. Alan Gross, Alexis, Andrew Stevenson, Arctic Fox, Astrosets, B-Bob Apocalypse,
Benjamin Mueller, Bob Crayl, Brett Mormon, Brian Cook, Burry Gowin, Christian Berghold, Conrad Haling, Daniel Loosely, David Boggerty, David Rossetter, Dr. Whoa, Dwight Elk, Iran Zegrev, Fairchild, Flower Guy, Frodo Tannenbach, Jeff McDonald, Glenn McDavid, Greg Davis, Hal McKinney, Jay Alex Anderson, Janelle Jean-Baptiste Lamatine, Jeremy Kerwell, Jim of Everett, Joe McTee, John Herman, Jonathan H. Staver, JP Sullivan, Kate Cendredo, Keith Murray, Kimberly Raik, Labrat Matt, Lee Harborn, Lana Spencer, Mark Schindler, Matt Rucker, Matthias Hayden, Michael Purshell. That's Stella Dicking. Stella,
Lana Spencer, Mark Schindler, Matt Rucker, Matthias Hayden, Michael Purshell, Michelle Cullen, Nala, Noah Albertson, Poldy Disney, Polly Middelink, Philip Walker, Red Bar is watching, RJ Basque, Robert Hindel, Ruben McCarthy, Sergio Sencevro, Sam Brooks and his mom, Scone, Sean Matt, Shabhana, Steve Rutley, Taz Tully, The Brain, Tiffany Rogers, Travis C. Porco, Van Ruckman, Will Field, and Zach Prokhandel. Thank you so very much. All right, thanks for one and we'll see you next week. Goodbye, everyone. Astronomycast is a joint product of Universe Today and the Planetary Science Institute. Astronomycast is released under a Creative Commons Attribution License.
So, love it, share it and remix it, but please credit it to our hosts, Fraser Kane and Dr. Pamela Gay. You can get more information on today's show topic on our website, astronomycast.com. This episode was brought to you thanks to our generous patrons on Patreon. If you want to help keep this show going, please consider joining our community at patreon.com slash astronomycast. Not only do you help us pay our producers a fair wage, you will also get special access to content right in your inbox and invites to online events. We are so grateful to all of you who have joined our Patreon community already. Anyways, keep looking up. This has been Astronomycast.
More episodes
