Daniel and Jorge Explain the UniverseDaniel and Jorge talk about the mysterious, unexplained "space roar" and whether its a clue about something new in the Universe.
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Hey, Daniel, do you ever think we should explore the universe with all five senses?
Hmm? Well, I'm definitely a fan of looking out into space.
Yeah, but we have other senses. Have you thought about what space smells like?
Well, astronauts report that space smells a little bit like a barbecue.
Really does it taste like barbecue?
Also, I don't know, maybe frozen barbecue? I guess. Well, I hope it doesn't feel like barbecue. Space is not that saucy it turns.
Out or sound like barbecue.
That would just be the sound of aliens preparing their barbecue grills.
Well, let's just hope we're not on the menu.
Talk about first contact, first course race.
Of course, I am more handy cartoonists and the creator of PHP comics.
Hi, I'm Daniel. I'm a particle physicist, and I do love me a barbecue.
So it really smells like barbecue? Space?
It does. Actually, we had a listener question recently about what space smells like and there are a bunch of really interesting organic molecules out there in space that like cling to space suits and then release themselves when you come back inside, and they smell like sometimes like sulfur, sometimes like barbecue.
What does it mean? Like the astronauts will go out into space on a spacewalk and then when they come in they smell like barbecue.
Yeah, exactly, when they open up their helmets again after they've come back in, the stuff that's stuck to their spacesuit now goes up their nostrils and it smells a little bit like barbecue.
The technically barbecues are part of the universe. Yeah, the universe does smell like barbecue, as it does smell like other things.
Our barbecued universe.
Welcome to our podcast Daniel and Jorge Explain the Universe, a production of iHeartRadio.
In which we use all sorts of absurd food analogies to explain to you what the universe is like. Is it goopy and saucy, is it chewy and stringy? Can you bite right through it? But really we want to make sure that you understand the nature of the universe, the things that scientists are thinking about, the things that we are mentally chewing on and the things we have not yet been able to digest.
That's right, because even analogies are part of the universe, and so it's a broad topic that we are discussing here.
Daniel and Jorge explain bad analogies with other horse analogies.
It feels like we just becompounding the problem there. But it is a pretty interesting universe out there, and there's a lot going on. Like if you just sit there in space and you float, you can smell things, you can feel things, I'm sure radiation hitting you, and you can see only a lot out there in the universe.
Absolutely, and we are continuing to invent new ways to interronte with our universe. And basically every time we do, we find something shocking, We discover something else out there in the universe we didn't even know existed.
Yeah, I mean, we're just sitting here in one corner of the Milky Way, which is sitting in one corner of the observable universe, and we're getting a lot of signals from everywhere. Basically, anything that gives us light, we get that light, and we detected with our telescopes and our antennants exactly.
We are drowning in information from the universe, much of which we didn't even know existed until recently. For example, most of astronomy has been done using visible light, light that you can see with your eyes, and even maybe enhanced with telescopes. But there are really interesting signals in X rays and on the other side of the spectrum down to radio waves. You can also look at all the particles that are washing over us, neutrinos and other crazy sources of information about what's going out there in the universe. And recently we added gravitational waves to our toolkit for listening to the universe. And each of these tells us something different about the nature of the universe because different stuff out there emits in different ways. Some of it gives off light, some radio waves, some gravitational waves. Each one can tell us something different about what's out there in the universe.
What sense would you use, Daniel to describe detecting gravitational waves? Like, what sense do you need to detect gravity? Do you feel it? Do we hear it, do we see it?
You would feel it technically because it's a space quake, right, It's like a shaking of space itself. Space contracts, it expands and wiggles, so that's really what's happening. And a lot of science communication about gravitational waves, though they talk about listening to the universe. They talk about like the chirp of black holes. I think that's a tiny bit confusing because we're not using our ears to hear these things. We're not getting sound waves from gravitational waves. What they've done is taken the frequency of those waves, transform them into sound waves, and then listen to them.
We're feeling the gravitational waves.
Yeah.
I like thinking about gravitational waves as the shaking of space.
All right, Well, there are a lot of things out there giving of a light and signals and gravity, and for the most part we sort of know where it's coming from over or what's making these signals. But sometimes there are surprises.
There are almost always surprises, and a lot of times these things are picked up by accident. Somebody develops a new kind of antenna or a new kind of telescope and looks out of the universe the first time, maybe looking for one thing and finding something totally different, and then puzzling over it and wondering like huh, what's making all that light? We're emitting all that radiation? And those are fascinating clues that tells about something new out there in the universe or something we knew about that's doing something we didn't know about.
Yeah, and there is one particular signal out there that is basically all around us. You can hear it in every direction, but we don't know what's making it. It's sort of this weird, unexplained phenomena exactly.
And it's also got a hilarious name to it. Oh does it in physics? How surprising? I'm shocked, hilarious and some ways misleading. Well, today on the podcast, we'll be tackling the question what is the space roar now, Daniel? Is it like a roar like a lines war or is it more like a cat's mew like rare.
Like?
Is the universe caddy or is it you know, not had its morning coffee yet?
What is the universe's attitude exactly? Does the universe need to go to therapy? Like, dude, chill out, Somebody give the universe some valium.
What's definitely cool and chill. We've I think we've established that. And does it get kind of hot sometimes.
Yeah exactly. Roar is a pretty funny name. Really. I would have called this the space hiss, the space hiss hiss, yeah, exactly.
Like the space buzzes.
Yeah, the space buzz That would have been a great name for it.
The space hum space hum.
That makes it sound like alien music, you know, like Gregorian alien chants.
The space whistle while you work.
Yeah exactly. I think all of those would have been more accurate names than the space raur.
Now see now you're calling it row. I would spell that differently than roar.
Oh yeah, that's more like the space meal.
Yeah. Yeah. But anyways, it is a thing, the space roar, and it's kind of a big mystery in physics, and we were wondering how many people out there knew what it was or had heard of it or been I don't know the subject of its attitude.
So thanks to everybody who is willing to guess at the true nature of something poorly named by astronomers. If you are willing to participate for a future episode, please write to me to questions at Danielandjorge dot com.
I like how you just totally threw astronomers under the bus. There you could have said physicists. You definitely specifically said astronomers there.
Yeah, well, I feel like they are the target of your criticism more often than other kind of physics.
So, mister particle man, are you serious.
Yeah, we got strange names, we got charming names, but you know, the astronomers there, maybe let's call them more creative with their names. Remember that whole episode about space centaurs.
Let's not hear me Rara about this topic any.
Longer, all right, let's not hiss about it.
All right? Well, as usual, Danel went out there and ask people what they thought the space roar was. So think about it for a second. If someone asked you, what would you say? How would you answer? Here's what people had to say, same as it's called aurora.
I imagine it's got to do with soundwaves, and I think they might come from all directions in space.
The space roar sort of reminds me of a tiger or a lion. But in our universe, I think that the space roar could be like an explosions. Maybe it could be compared to the Big Bang, and maybe this explosion was the beginning of something. I don't know if it could have been the beginning of a galaxy.
The spice roll, I'm fairly certain is aliens.
Probably it can only be radio waves, since nobody can scream at us, we wouldn't hear it because you avoid the sound cannot travel, So the space road can be in radio.
We always talk about light and energy being transmitted through space, but a lot of what happens in the universe also produces or could produce sound if there was something to convey that sound. So is this some sort of accumulation of that. I have no.
Idea, all right, I like this idea of a space tiger or a space lion, an alien space tiger.
Yeah, that was basically your answer.
Yeah, and some people assume it has something to do with radio waves or at least some sort of waves that we're getting out there from the universe.
Yeah, totally solid response there.
Yeah, but technically can when you get sound from space, I know, and space no one can hear you scream. But is that because you're wearing a helmet or because you can transmit sound?
Right? Anything where you describe something we get from space in terms of a sound is usually playing the same trick we talked about with respect to gravitational waves where you're getting some other kind of wave, and all waves have a frequency, and then you transform that wave into a sound wave so you can listen to it. This is no different than like taking radio waves or X rays from space which you can't see visually, and then just shifting them in the spectrum so that you can see them like a false color image. So, no, you can't actually hear any sounds from space because sounds are mechanical waves. They require like air shifting or something banging into something else. So we can't hear anything technically from space.
Right, But space isn't completely empty, right, It's not a perfect vacuum. There's a little bit of gas and hydrogen everywhere, isn't.
There No, exactly, there are some particles out there, So you could imagine there are some like waves in the solar wind, for example, oscillations that happen like the sun has a period of eleven years, where like there's lots of ups and downs in the radiation it emits, So you can imagine waves propagating in that medium, and perhaps you could imagine actually listening to them. So yeah, there are ways you're right for sound to propagate through not totally empty space. But space is also not empty in another way. We always talk about space being filled with quantum fields, and those fields can't propagate waves, and for example, that's what a photon is. It's a wave in the electromagnetic field in otherwise empty space.
Hmm, sounds good. So they can hear these scream in space from radiation burning probably.
Yeah, if you scream in light, then yes, people can hear you scream.
All right, So there's this big mystery in physics called the space roar. Now, Daniel step us through this, what is the space war?
The space roar is a totally weird, unexplained source of radio from space, and that's why they call it the space roar because it comes in the radio spectrum, which is a spectrum where we often listen to. Right, you might even be hearing this podcast on the radio, which means it's been transmitted using radio waves. So, because we associate radio waves with sound often, I think that's why I got this name, the space roar. But basically it's unexplained source of radio waves from space.
I guess, meaning that if you turn on your radio, you would technically be able to listen to this rar. Right, Yeah, exactly since it is coming in through the radio waves.
Mm hmm. You need a radio antenna. And remember that radio waves are just another part of the electromagnetic spectrum. All these are photons. You could call all of it light if you want, but they're all just part of the same wiggling of electromagnetic fields. In the center of the spectrum. There's visible light. Above that there's UV light, and then X rays below it, there's infrared light, and below that are radio waves. So radio waves a just photons with a very very long wavelength. And you know, as we were saying earlier, for centuries, people were doing astronomy only by looking at visible light, the light you could see with your eyes, and of course there's a lot of fascinating information about stars in the universe you can see you just with your eyes or gathering more of those visible photons into a telescope. But in the nineteen thirties it was this amazing discovery that you could actually listen to the sky using radio waves also, and that there was a huge source of radio waves coming to us from space.
How did we discover that? Was it through like actual radios?
No, it was really interesting accidental discovery. By this guy Janski. He was hired by the Bell Telephone Company. They wanted to beam radio signals across the Atlantic, and they were worried that thunderstorms would generate radio interference, so they hired him to like listen to the radio spectrum carefully and see if you could understand these forms of interference. So he built basically a huge radio telescope, the first radio telescope, just to gather radio waves, and he heard a lot of stuff that he couldn't explain as coming from Earth.
Hmmm, interesting, totally unintended.
Totally unintended. He it was like a fascinating little piece of science. He heard this weird hiss he couldn't explain, and actually he discovered that it was correlated with the rotation of the Earth, which is how he knew it wasn't coming from the Earth. It's like seeing something in the sky and you see it once a day, so you know that, like as the Earth is turning, it's appearing in the sky. But he was looking at the sky in a different spectrum, right, He was looking at the sky in the radio waves, and what he was actually listening to was radio emissions from the center of the galaxy. Wow, And so here was like a whole new way to listen to the sky, to look out at the universe. Nobody'd ever thought that there are natural sources of radio waves out there in the universe and by listening to them we could tell what's going on. And the whole field is hilarious sort of because nobody really did anything about it until about ten years later when this guy outside Chicago built the world's first radio telescope by himself in his backyard and he was basically the only radio astronomer in the world for about ten years.
Wow.
A pioneer, a pioneer, absolutely in his garage in his backyard. This thing is huge. It's one of these big dishes. So Janski's first one was just like a string of antennas on a big wheel that he could turn and then rever. He built the first dish to sort of like concentrate radio waves and collect them together. And that's the sort of radio dish that we have now. Like Aricibo until recently was a big radio telescope, and we have other big radio telescopes. You can see them. They're these huge dishes and have to be big because radio has very long wavelengths, right.
I guess it's sort of like, you know, maybe astronomers at the time were still busy trying to figure out what they were seeing in the visible light spectrum, and so nobody thought to look in other wavelengths.
Yeah, exactly. There's still plenty of astronomy to do in visible lights. People are still doing it now. But you know, there's a lot of spectra out there, and the universe looks different at different spectrum. You know, different things glow at different temperatures. Some things are very bright in the UV and very dark in the visible light, or they're very strong radio emitters and they're very quiet and the visible and so it's sort of like looking at the universe in color instead of in black and white. You can see different things light up in different things being dark at different frequencies, and so it's sort of like extra colors to the universe. It's really a great way to sort of understand what's out there, right.
Right, it's a great romantic line. And hear you're glowing in the X ray spectrum, all right, So that was a bit a hiss that he heard back then, But now we're hearing a roar and it's sort of unexplained. So what's the history of this roar when we first started listening to it or seeing it? And who did it?
So there's an experiment developed called the Arcade instrument. ARCADE is one of these tortured acronyms. It stands for absolute radiometer for cosmology, astrophysics and diffuse emission. But it's basically a really sensitive radio antenna attached to a balloon and it goes up in the atmosphere and it listens to radio waves and they're trying to really accurately measure these sources of radio waves because they want to understand things like the very early universe. They want to listen to the cosmic background radiation and detect to see if, like the first stars in the universe gave it a little bit of hot spots here and there. So they launched this probe something like ten fifteen years ago, and it was one of the most sensitive probes to radio waves, and they heard this crazy hiss that they couldn't explain.
Wow, where did they launch it? Was this one of these like antarctic balloons or was it outside Chicago? Also the epicenter of radio astronomy.
It was launched from a spot in Texas. NASA has a scientific balloon facility there, and this thing is not just like a normal balloon. It's one of these like massive weather balloons, and as it goes up it gets really really big. And this thing went up to thirty seven kilometers above the Earth's surface.
All right, So then they send out this balloon and they I guess were they able to point it? Can they point it around? And that's when they heard this roar.
They can't point it. It's just sort of like flats around. They don't steer it. But it has a bunch of antennas on it, so you can get directional information about the signals you're picking up based on like when they arrive at the instruments. It's sort of like parallax or like binocular vision, and so they can't tell where things are coming from. And so you know, they saw a lot of the expected stuff in the radio. You can see the Sun, you can see the galactic center, you can see Jupiter, you can see other galaxies that are putting out radio waves, and that's sort of what they expected. But they also found this sort of like overall signal, this uniform hiss that nobody'd ever heard before, and it's much much stronger than anything they expected. Hmmm.
Interesting. All right, let's get into a little bit more in detail of this his and then let's talk about where it could be coming from and what it could be. But first let's take a quick break.
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All right, we're talking about the space roar, a mysterious signal that the Arcade instrument detected on a balloon thirty seven kilometers up in the sky. Now, Daniel, this is different than the cosmic microwave background radiation, right, the cmb R.
That's right, This is different from the cmb no R. We're not living in the Marvel universe. The CMB does emit in the radio. Right. Part of the CMB is in the radio spectrum. It's a bit of confusing terminology here because sometimes waves in this part of the spectrum are called radio sometimes they're called microwaves. It truly the same thing. Essentially, anything longer than a millimeter you could call it radio wave, or you could call it a microwave. So you could also call it the cosmic radio background.
Mmmmmm, So it is sort of like the cosmic microwave background, but it's just at a different waveline.
Yeah, exactly. They were looking for at the slightly longer wavelength portion that's not as well studied, because what they wanted to understand was can they see like the heat the light put out from some of the first stars in the universe, which would have emitted in the radio. That was sort of their scientific goals, like measure this part of the spectrum really really accurately and then study it for hints about the formations of the first stars, which they hoped would leave a little fingerprint on this part of the universe.
Oh, I see, they send that Balluna up to study the CMB specifically, but in the radio wave wavelength.
Yeah, exactly and to study sort of the longer tails of the c B, which people haven't studied as precisely using like Kobe and Plank and w MAP and those other satellites. So it has a slightly different sensitivity than other instruments. So sort of the first time people looked with this precision at this part of the spectrum.
Mmmm, all right, So then I guess they expected to hear like a background his but what they found was not quite what they were expecting to find.
Yeah, they expected to find the CMB, as we talked about that's part of the spectrum. They also expected to hear sort of like a diffuse background. You know, like all the galaxies that are out there, they emit in the radio, especially if they have a strong black hole at their center, they're going to be giving off a lot of radio waves. So you expect sort of just like a diffuse source of noise out there in the universe in radio waves. But they heard this hiss. That's not the CMB. It comes at a different wavelength, and it's much much stronger than what you would expect just from like all the galaxies emitting. It's like six times larger than what we can.
Explain, Wait, why can't it be the CMBA.
Well, we know the CMB pretty well. The CMB is what you expect from like a two point seven degree kelvin black body emitter, So we know its spectrum and we know its intensity. And this is just much bigger than the CMBs. That's not consistent with what you would expect from the CMB mm.
I see, And it's much bigger than what you would expect from just a general din of the universe. Yeah, like the general radio wave background of the universe.
Yeah, exactly. And it's the most sensitive instrument in this area. And it also has an absolute calibration, which is the reason we first heard it. Most of the radio balloons and other things listening to this part of the spectrum before would always just do a relative calibration that would like, listen to two points and look for example, at radio from the center of the galaxy relative to just sort of like an average direction. So previous experiments couldn't detect like an overall background noise because they were always like measuring relative to the background noise. This is the first experiment that can actually measure the background noise itself because it has an absolute calibration on it. And so this is the first time we realized that the background noise that Din you were talking about is just much larger than what we can explain. You know, It's like if you walked into a room expecting there to be ten people in there, but instead there's the noise from sixty people. You're like, where's all this noise coming from? Mysterious Yes, something out there in the universe.
Like this one. They calibrated by I guess shielding it completely or just having like knowing their instruments so much that they know what no radio emissions would sound like this thing.
They shield it, they cool it down to two point seven degrees kelvin using super fluid liquid helium, which is pretty awesome. And then they also have a device on there which gives out a known signal, so like it has its own little calibrator on it which they can calibrate absolutely, like they know what they should be hearing from this. So rather than just using the sky to calibrate where you're sensitive to background noise in the sky, they have their own little calibration source. This is like a little add on thing they did to make it more sentence so they could like calibrate it more precisely. And what they discovered is like ooops, the background from the sky was much bigger than what everybody had thought, and nobody had been sensitive to it before because nobody else had done their own calibration.
I see now, is this coming from a particular direction or it's like it's coming from everywhere.
It seems to be coming from everywhere, right, It's really weird. It comes from all directions and we don't know yet, like is it coming from our galaxy or is it coming from other galaxies? It's really confusing.
If it was coming from other galaxies to be pretty surprising, wouldn't it, Because they're so far away that that signal should be pretty weak by the time it gets here, So it would be a pretty big source at those galaxies.
It would be you know, some of those galaxies really pump out radio waves. All galaxies put out radio for example, like Andromeda, it puts out ten to the thirty two watts. Like that's just a huge number. It's hard to wrap your mind around. You know, your light bulb is like fifty watts or one hundred watts. Andromeda puts out ten into the thirty two watts, you know, and it's all noise. It's not even like playing good music or anything. But that's actually a fairly quiet galaxy. Some of the galaxies out there, like Sickness A. It puts out a million times as much radio energy. So these galaxies, you're right, they're really far away, there are millions of light years away, but they're still very loud in the radio, which just tells you how intense they are.
Could those be the source of this space we are?
Well, that was the first idea, is that people thought, oh, well, you know, maybe the galaxies are louder than we thought, but we can listen to the individual galaxies. We can tell basically how loud galaxies are. In order to explain it with galaxies, you need to just like add more galaxies because you need this like diffuse emission not just from individual galaxies. But there sort of isn't enough space to add more galaxies. Like if you just said, what if there are a bunch of galaxies out there we didn't know about somehow, then you'd have to like pack them into the universe like sardines. And so you can't really explain this just by like adding more galasalleaxies.
Mmm, so it can't be galaxies? Could it be something specific? Like you know, there just happens to be like a like a pulsar aimed at us or something like that, or a quasar.
It's coming from all directions, right, So what you need is like a very large population of something, all of which is emitting these sources.
And emitting sort of like noise too, right, like not any frequencies in specific.
Yeah, well down here in the radio. But exactly, it's not like a spike. It's not like a very narrow peak. And you know, and maybe we should talk about like why things emit radio because that helps us understand what it is that's generating this sound.
All right, Yeah, what makes things imi radio waves?
Well, we have a few sort of categories of things that can make radio waves. One is just things being hot. You know, everything in the universe gives off radiation. It's called black body radiation depending on your temperature, and things that are really hot give up higher frequency radiation, you know, for example, like X rays and ultra violet light from really really hot things, things like the sun give off in the visible spectrum, things like cool clouds of gas and dust give off in the infrared, but things also emit in the radio. So like big dark dust clouds out there in space that are really pretty cold, they glow in the radio spectrum. That's one source of radio waves. Another source comes from just like magnetic fields, charge particles, when they move to a magnetic field, they get bent, like for example, when the solar wind hits the Earth's magnetic field, you get the Northern lights. Right. The particles are emitting light when they bend, because anything that accelerates, anything that turns in a magnetic field, has to give off a photon to do that, and if things have the right speed, then those photons are radio waves. And so if you have charge particles moving through a magnetic field, you're gonna get photons, and sometimes those photons are radio waves. But maybe my favorite sos of radio waves is that it turns out that there are sort of natural molecular lasers out there in space.
Natural molecular lasers.
Yeah, exactly. You know, a laser works when you have light passing through a resonant cavity as a material in it that can sort of amplify it. And we don't want to go in detail into the physics of lasers. But there are sometimes out there in space, these dense pockets of molecular clouds, and if life passes through them at the right frequency, it can become a maser, which is basically a laser, but in the microwave spectrum. And I remember microwaves and radio waves basically the same thing. And so sometimes out there there are these basically radio lasers just sort of naturally occurring.
Wow, So the could those be what's cassing these space roar?
No, we don't think those things happen often enough to explain the space roar. They wouldn't be coming in every direction. Those things typically come from like dense clouds inside our Milky Way. But these emissions don't follow the pattern of the Milky Way right, Like, they don't lie along the plane of the Milky Way. Remember, the Milky Way is a flat disc. And so if these things were coming from our galaxy, from something in our galaxy, you would expect it to be like in the disk of the galaxy that when you pointed your intennas away from the galaxy, it would get fainter. But it doesn't. It seems to be in every direction. So either the Milky Way has some new structure in it that tends to be like a spherical halo around us that's emitting this or it's coming from somewhere outside the galaxy.
Hmmm, Like it doesn't seem to get louder when you sort of listen towards the center of the galaxy. It's like pretty even all around this.
It's pretty even in every direction. And that's why they call it this space roar, because it's just like filling space with this.
Sound right right, Trying to make a statement, But to.
Me, it's really exciting because it's like a puzzle. It's like something out there is giving off this radiation and we don't have an explanation for it, and that tells us that it has to be something new, and we're about to learn something new about the universe. Something in the universe has been screaming at us forever and we only recently heard it, and so that to me is exciting because it makes us be creative about what could possibly be out there. Is it something we're familiar with that's screaming in a way we didn't expect, or is it something totally new out there that's creating this crazy radiation.
Right, And I guess they're pretty sure it's not a technical issue, right, Like, they've calibrated this pretty good.
They've calibrated this pretty good. Exactly. They were really surprised to see this, so they spent a long time. This is not like an aha moment one evening. You know, they did this flight in over the lasted several days, but they spent months and months and months analyzing this data, removing background noises, removing other background noises, checking for sources of mistakes and uncertainty, and calibration and cross checking and redouble cross checking, because you know, it takes a lot of guts to publish a paper like this to say there's something we don't understand in our data. Your fear at night when you wake up the middle of night you're like, wait a second, did I remember to check for this thing? Is that you overlooked something simple, that you're making a mistake. It's exciting, right to say we found something new we don't understand, but it's also a little terrifying. So they definitely cross their t's and dot their eyes. These are very careful.
Folks, especially this one, because the discovery is not very specific, right, I mean they're basically saying, hey, we're getting a lot more noise in our instrument than we think we should, which normally just means that you're not doing it right right, But here they're saying that this could be something new in the universe.
Yeah, they're pretty sure this is actual signal from space and not just an artifact of their instrument. And you know, this is a very carefully engineered instrument, like they are flying liquid helium up in a balloon, like they spent a lot of time designing this thing. I read the design paper and it's very detailed. These folks definitely did their homework, and so I certainly believe that this is a signal from space, which now lets us wonder about, you know, what is it. You know, another aspect of writing a paper like this when you see a new signal from space is you're sort of putting it out there and you're not naming the source of it. You'd love to see a new signal from space and at the same time explain it because you're like, wow, look a new signal, and we discovered something new. Here's the explanation that would be like a complete sign antipic story instead you just sort of publish the experiment and then go I don't know, and then everybody gets to play with it. But it sort of opens the door for somebody else to come in and explain your discovery, right right, Yeah, it's very open and collaborative. That's pretty good, all right.
So it can be other galaxies because there aren't enough galaxies to make up this background roar, and it's probably not a magnetic field or the cosmic microwave background radiation. So the question is what could it be. Let's talk about that, But first let's take a quick break.
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All right, we're talking about the space Roar or row, otherwise know one as the cosmic radio background noise.
Kind of, yeah, part of it exactly.
Yeah, Yeah, So we tacked off a couple of things that it can't be. It can't be galaxies, it can't be magnetic fields potentially, So what could it be?
Daniel, Well, as usual, we have a spectrum of possibilities ranging from like pretty boring to totally bonkers slash exciting.
I'm gonna guess we're gonna start with the boring and build up to the bonkers one.
Absolutely, so sort of the most boring explanation is that maybe there are just more magnetic fields than we thought. Remember, when charge particles fly to magnetic fields, they bend, and bending means acceleration, and when any charge particle accelerates, it has to give off a photon. It's just basic conservation of momentum. You can't move in one direction without pushing something else off the other direction, and that's usually a photon. So if magnetic fields out there are stronger than we thought they were, then there's gonna be more of this kind of radiation from charge particles than we thought. And if there's sort of everywhere, then charge particles everywhere are gonna be basically roaring at us. And remember we did an episode about whether or not space itself is magnetized because we've been discovering, as we've been trying to measure magnetic fields through the universe, that magnetic fields are kind of everywhere, Like there's definitely one from the Earth and the Sun and Jupiter, and even our galaxy has a magnetic field. But recently we discovered that there are magnetic fields between galaxies and between galaxy clusters, and there might even be magnetic fields out there in the huge voids where there's just nothing. So it might just be that space has more magnets than we thought, which leads to more particles roaring at us.
Right, maybe the universe is just more attractive than we thought. Yeah, it has a certain glow to it basically, right, Yeah, exactly, it's more active than we thought, you know, and it's more magnetic. There's more things that you can't really quite see that are happening in there.
M M. And you know, you need two ingredients to make a roar from magnetic fields. You need the magnetic fields, and then you also need the particles. And as you were saying, space is not empty, right, They're particles everywhere, even between galaxies. In fact, like something like half of the stuff in the universe is the intergalactic plasma, this stuff between galaxies. So there are a lot of particles out there flying through these magnetic fields, and if they are larger than we expect, that could be the source of the space roar.
Right, But do we know what's causing these magnetic fields or what would cause the magnetic fields to be that strong for it to generate this roar.
We definitely do not know the source of these magnetic fields, which is sort of like awesome and crazy. That's something as basic as like the magnetic field. Though the universe can't be explained. People are talking about like weird unknown mechanisms inside galaxies or between galaxies. But my favorite possible explanation for what's causing these magnetic fields is that maybe they are primordial, Maybe they date from the origin of the universe itself. That when the universe was created, some energy just sort of like slipped into a magnetic field and then got stuck there. So it's like leftover energy from the Big Bang captured in a magnetic field still around.
I see it's in the DNA of the universe.
Yeah, it could be. It could be people have forever assumed the default configuration should be like no magnetic field, no stuff, no moving charges, no magnets, no magnetic field. But it mightn't just be that. The baseline situation for the universe is to have magnetic fields in it. So if you find that stuff interesting, check out our whole episode about is space magnetized?
All right, and that's a vanilla explanation. Then some of the universe is inherently magnetic to a super high degree than we thought it was possible. What's our next possibility?
Next possibility is stuff happening.
You know, we talked about that's a technical term, stuff happening. Isn't that just the column definition of physics physic stuff happens.
Yeah, But in this case it'd be exciting stuff happens. Exciting stuff happens. Yes, Exciting stuff is happening out there in the universe. And in this case it might be galaxies dancing around each other and eventually merging. You know, these galaxies are sources of radio because they're black holes and because the big clouds of gas and dust that are in them. And it might be that when galaxies merge, that that merging forms some turbulence, and that turbulence sort of like gets these clouds of gas and dust to emit in the radio waves louder than they otherwise would. And so it could be that there's part of this process of galaxy merging that we don't quite yet understand.
Oh, I see. It could be something normal happening, but that when it happens at an extreme level, we just don't have a good model for it. So maybe that's what's generating these waves.
Yeah, instead of having more galaxies out there, have the same number of galaxies, but have them do something different from what we expected. So maybe there's more of these mergers happening than we thought, or the mergers are more turbulent than we thought, and that's what's giving off this roar. So not new stuff, but old stuff doing new and exciting things, teaching old galaxies.
New tricks, right, physics stuff happens in any ways, all right, So it could be merging galaxies. What else could it be.
It could also just be something new out there in the universe that's giving off radio missions that's not on our list of things we understand. You know. It could be not stars, It could be not the centers of galaxies. It could be you know, not black body emission. It could be some new source of radio emission.
That we somehow have missed all this time.
Yeah, we somehow have missed. And people have even connected it, for example, to our favorite universe mystery, which is dark matter. R hat it might be that dark matter is out there and that it can annihilate with itself. Remember, dark matter, we know is something massive that's out there, but we don't really know what it's made out of. One hypoth for dark matter is that it's the really heavy particles that mostly just sit around and do nothing. But it's sort of hard to explain how you get dark matter and how you have the amount of dark matter that we have in the universe if there's no way for dark matter to be created or for it to annihilate itself. So people have thought of this idea that maybe dark matter sometimes bumps into itself and then annihilate. It's just like particle antiparticle. Maybe this dark matter and anti dark matter, and sometimes it bumps into itself and then turns into for example, normal matter like electrons and positrons.
I see. So maybe all this dark matter, because there's a lot of dark matter in the universe. Maybe that's what's causing this glow. That's the idea. Yeah, and that would make sense because dark matter is pretty diffuse out there. We're sort of surrounded by it in a halo and in our galaxy.
Mm hmm.
That would sort of make sense.
That would make a lot of sense. So in more detail, the mechanism is that these dark matter particles annihilate and then create these electrons and positrons. But because dark matter is heavy, like it's much heavier than electron or positrons, these particles would be created with sort of a lot of energy. It'd be flying through the universe and when they hit magnetic fields they would bend and then they would give off some radio waves. And so it could be as you say that this is sort of a signal of a lot of dark matter surrounding the galaxy and giving off these electrons and positrons which then roar at us. Dark matter we know there's five times as much of it as normal matter, and as you say, it's not spread through the galaxy, and the same way that normal matter is, it tends to make up this big halo. It surrounds everything and it's fluffy and diffuse. It's not as clumped, and so that would be a good explanation.
Wow.
So basically dark matter would not be dark, that's what you're saying. You would have to rename it, or would you continue with this incorrect name.
It would still be dark. It just wouldn't be quiet, right, It'd be like screaming the matter.
See now you're mixing the metaphors or Daniel, so you're saying it's not quiet.
It's so much fun to mix your metaphors and put silly names on. I see why astronomers are tempted.
I see you just threw them under the bus again.
No, and now I'm joining them. I'm saying, you know what, I get.
It all right. So it could be dark matter. That would be pretty exciting and pretty far out there. But it gets in wilder, it.
Gets even wilder. I was reading some sort of bonkers ideas that there could be alternate universes out there. Right. This is like the multiverse theory, the idea that our universe is not the only universe that's out there, there are other universes out there, and that these universes sort of echo with ours, and there are even ways for our universe to communicate with those universes, for like radiation to slip from our universe to their universe. And there's this crazy idea, this Fredkin Wolfram automaton, which spreads across multiple universes that like lives in more than one universe and gives off radio signals, and so the idea is like, maybe this could be evidence of other universes.
WHOA, yeah, like you're seeing like the shadow or the glow of other universes that are sort of on top of ours.
Right, yeah, exactly, And I don't want to be too clickbaity, like this is total speculation and it's not a prediction. Like if this was an idea that had been invented before we heard it, and somebody said, I think there are multiverses out there, and you can prove it if you hear this particular thing, go out and look for it, and then we found it. Now would be convincing, But you know, once you see it and you don't know how to explain it, and then later you cook up a crazy multiverse explanation for it, it's sort of less convincing as an explanation. It's always more impressive to predict something than to postdict something.
Right, But isn't that technically the same thing, Daniel. It's like it just depends on the order in which you do it, but it's still the same sort of connection, right.
I don't know. I think the order sort of matters. Like, you know, naming lottery numbers after they've picked the lottery is a lot easier than before. Right, It's sort of the same deal. Like telling the past is a lot easier than telling the future. So I think order matters.
Yeah, right, right, But I guess what I mean is that they could still be right. Oh, just because they came up with it afterwards doesn't mean that they're wrong.
Absolutely. They could still be right, absolutely, But it's not really like evidence for their theory. You know, it's not that hard to come up with a theory that describes what you see. What's hard is to come up with a simple theory that explains what you see, which means it's capable of making predictions. That's what science is about, right, It's predicting the future, not just describing the past. So you're right, we can't rule out this idea. The only way to rule it out is to do future experiments to compare against their predictions. So it could totally be that we live in a multiverse and that the space war is you know, a sound from these other universes or radio emissions from these common overlapping elements of our universes could totally be But you know, I don't want to oversell.
It right right, I wonder if it could it be something more mundane, like could it just be I don't know, like rada ways coming from our technology, Like could it be the just human noise, or I guess you would hear it only coming from Earth.
Yeah, exactly, it's not connected to the Earth, right. It seems to be coming from every direction and it's independent of the orientation of the Earth. And also one of the reasons they launched this thing on a balloon was to sort of trying to get away from earth bound sources of noise. You know, the Earth is very loud in the radio these days because there's so many cell phones and radio emitters. They're basically everywhere I see. A good place to do radio astronomy is like on the dark side of the Moon because it's shielded from the Earth, but it's kind of hard to get there. So launching a balloon into space is a good way to sort of insulate yourself away from a lot of sources of earth bound noise.
Well, I think I got it, Daniel, What is it? I think it's cell phone signals from aliens, Like it just happened to be in the middle of a couple of you know, intergalactic alien cell phone towers, and that that's what we're listening to.
I can't believe nobody else has suggested that idea.
Right, it's obvious, and I came up with it before getting in my hands into the data, so technically counts.
Well, then the question is, why are these aliens roaring at each other? Like what's going on? Can't you guys just calm it down? You know, what's the cosmic equivalent of like knocking on your ceiling with a broomstick.
Well, they're just on the phone, changing emojis and memes, and you know, we just don't know how to decode it. That's all.
Well, we're busy here trying to listen to the origins of the universe and understand, you know, the heating of the first stars, and they're just like chatting with each other, and we can't make out these cosmic signals.
Yeah, yeah, well that's what life is.
All about, learning to live with your neighbors.
Hogging to your fellow sentient beats. All right, So it's a big mystery in astronomy and physics, and there's this big roar. So it's still a mystery, and so what are people doing about it than you?
Well, of course they are proposing new projects, spend more money to gather more data. There's this plan for a new version of the Arcade experiment that's going to be much bigger. It's going to have five hundred gallons of liquid helium, which is going to allow it to be even colder and stay more sensitive. To get like more data, maybe we can look for some variations. Maybe we can see if it's a little bit stronger in one part of the sky than somewhere else. So that's one possibility. So we could just sort of like get more resolution on the problem that might give us a clue. We also have ground based instruments, and now that Aricibo is in the past, unfortunately, that's most powerful radio telescope in the world is in Green Bank, West Virginia, which is the beautiful instrument you should google it and check this thing out, and it can make very precise maps of the skies and these radio frequencies. Again to look for patterns, right, because even the cosmic microwave background has patterns to it, right, and those patterns are important. There's a huge amount of information encoded in those patterns. So we're just the very beginning of understanding this other map of the sky and what's in it and what it means.
Cool, all right, So maybe expect more in the coming years. But in the near future it's going to be a big mystery. If we are bathed in mystery. There's a huge source of radio waves that is coming from all over space and we don't know what it is. Yeah, we won't know for a little while.
Yep, until we hear more roar.
In the meantime, Universe, we hear you. We hear you roaring. We respect you, We get it. Maybe chill out a little.
Bit, exactly, We're doing our best to figure out what you're roaring. It is all about.
May it's the universe hitting the brustick underling at us because we're being too noisy.
Exactly. Maybe we should learn to shut up. Too many podcasts and on that note, thanks for listening to this.
One, Thanks for joining us, See you next time.
Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of iHeartRadio. For more podcasts from iHeart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact. But the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. How is you as dairy tackling greenhouse gases. Many farms use anaerobic digesters to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as dairy dot COM's Last Sustainability to learn more.
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