Daniel and Jorge Explain the UniverseWill our lives be affected when the Milky Way collides with Andromeda?
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Hey Daniel, what keeps you up at night?
Oh? I worry about a lot of things. Financial crises, my kids growing up to be just like me, all sorts of stuff.
I worry about that too, for them.
You worry about my kids growing up to be just like me. We can't have more of him in the world.
Okay, But like on a galactic scale, on a universe scale, what's something we should be concerned about?
Well, we do have a lot of things to look forward to in terms of our galaxy. If we survive the sun exploding in the waters are boiling off, then we have something pretty dramatic to look forward to, which is that our galaxy, the Milky Way, is going to collide with their nearest neighbor and.
Drameda meaning right now there's an entire galaxy and drama heading towards us at this very moment.
That's right. It's like somebody shot it at us with a slingshot and it's zooming right towards us, and it's going to hit us smack on.
Hi.
I'm Jorhek and I'm Daniel, and this is our podcast Daniel and Jorge explain the universe. On the episode today, we're going to talk about.
What will happen when galaxies collide. Is this something we should all be worrying about and packing our bags, about building our underground shelters or we all screw or is it just going to be like a big nothing?
Yeah?
How much should I pack?
You should definitely be stalking lentils no matter what. Lentils are a good investment for any of these ends of the world stories. Not just beans, no, no, Lentils. I mean lentils are a kind of lego.
For a galactic emergency. That's the one to go with.
Yeah. Absolutely, I would invest in lentils heavily. And it's not just because I happen to purchase lentil stocks just before we recorded this podcast and I'm trying to drum up the lentil futures you know, I'm sincerely worried about our listeners, and I encourage you all to go out there and stock pile lentils.
Well, that's a whole hill of beans worth of advice right there.
That's right. And so this is the question in today's podcast, what will happen when our galaxy, the Milky Way, collides with the neighboring galaxy? And this question I love not just because it's huge and dramatic and galactic and all this sort of stuff, but because it was suggested by one of our listeners.
That's right. It's Blake from Australia who listens to this podcast on her commute to work every day.
That's right. And she didn't tell us what she uses to commute. Maybe she rides an beautiful pickup truck. Maybe she's in the back of a limo.
Maybe she writes the Kangaroo.
Yeah, who knows, that's right with a really nice sound system.
Yeah, but she has some interesting feedback for us about our podcast. Right. What did she say?
Yeah? She said that she likes listening to me explain things, but she also likes when you interrupt me. She said that often you interrupt me just the same moment when she has a question and you pose the same question that was bouncing around in her head that she was shouting at her Limo sound system or kangaroo speakers or whatever it is she using to listen to. And so I was glad for that because you know, I like when you interrupt me. Also, it breaks the flow and it keeps me from just droning on and on and on. So thank you Blake for suggesting this topic, and thank you Jorge for occasionally interrupting.
Yeah, I know, I'm happy to be rude.
It seems to come naturally. Yeah, yeah, And so that's the topic of today's podcast. And we thought first before we do, we would walk around like we usually do and ask people, are you worried about a galactic collision? What do you think will happen when our galaxy collides with a neighboring galaxy?
So put that image in your mind, two giant galaxies, full stars running into each other. What do you think is going to happen? Here's what people had to say, big explosion. We'd probably all die.
It is going to be mostly nothing because of all the empty space around the world, although there would be some crashes and so on in the way.
Okay, probably somewhere between a glacial, slow event that we won't even notice and nothing at all.
Maybe leaning toward nothing at all. I think it would probably be a big explosion with something pretty crazy happening. All right. That was a little anti climatic. People seem to have very low expectations of this event.
What do you mean. It seems like half the people were like, it's going to be nothing, and the other half are like, big explosions, We're all going to die.
Well, why do you do you think? Blake asked this question? Do you think this is something she's concerned about or is something she's curious about?
You know, I think Blake is probably deciding whether or not to stock up on lentils.
You know, she's probably right now as sorry, she asked.
I think it's part of just trying to be a sort of a citizen of the larger universe, you know, wondering where we stand and trying to think bigger than just our planet. You know, because there's so much going on out there, it's so easy to just walk around on the surfaces planet never really look up and remember that there's a enormous amount of stuff happening out there, and then you wonder like, well, how is that relevant to me? And is he going to ruin my life? Or can I go on ignoring it?
Right?
So, I think maybe she was just sort of thinking into the deep future and wondering, like, how long can this whole ridiculous, beautiful thing we call life on Earth go on?
Right? Is it going to change from how it is now?
Right? Yeah? Exactly? Do I need to change the way I live? Does it affect any decision making? On the other hand, it could be that Blake, like many people, is just to think her and likes to think about these scenarios, and she probably heard that the Milky Way will collide with Andromeda and wonder like, what's that going to be? Like? You know, this is this other side of me that likes to smash stuff together. I mean, I'm a particle physicist. But then we have the whole universe to play with, right, And so you might wonder like, what happens when planets collide? What happens when solar systems colide? Oh my gosh, what if we could build a galaxy collider and shoot them against each other and smash them into each other? Right, So it just comes out of like a curiosity to see stuff break by smashing it together.
Yeah, well, let's think a step back and just kind of think about why even galaxies would collide, Like, is this a relevant question that is this something that happens a lot galaxies colliding or is it something that's incredibly rare.
It turns out galaxies colliding happens all the time. It's like a totally natural thing.
Really.
And our galaxy, Yeah, not only will our galaxy collide with Andromeda in a few billion years, it's currently colliding with other smaller galaxies and.
What Yeah, we're in a collision right now.
Yeah, that's right. And remember that the galactic time scale are very different. You know, the galaxy takes about two hundred million years just to rotate once.
To go around once.
Yeah, so one galactic year is two hundred million earth years.
But it looks so swirly, It looks you know, you know what I mean, Like it looks like it's in motion, but it's actually it is.
In motion, it's just very slow, right, And so all these things are dancing around each other and sometimes they bump into each other. And the thing I think is amazing is that, you know, until like a hundred years ago, we didn't even know there were other galaxies. Like we looked up at the night sky and we saw stars, and we thought, oh, there's just stars that go on forever. Right, the universe is just filled with stars.
The universe is just like a giant mess of pinpoints, right, just stars.
Yeah, yeah, like somebody hit scattered stars across the cosmos, right, And it was Hubble, the guy for whom the telescope and the constant are named. He's the guy who figured out, oh, some of those things that are really far out there are not stars. There are other galaxies. Right, So there's the universe is filled with other galaxies. And of course there are more galaxies than stars. And then each galaxy, of course contains hundreds of billions of stars, and so the numbers pretty quickly blow your head up before you can understand them. But the point I wanted to make was that we didn't realize there were galaxies until recently, and now we're realizing that galaxies are in motion relative to each other, and they're moving. Now, these galaxies that we see out there in the sky, they're not just like hanging there in space never to change. Right, They are moving their dynamic things, and they're constantly in motion, and they have huge gravitational attraction.
Well, let's break it down. What exactly is a galaxy? I mean, I know it's kind of like a collection of stars, But you know, why do stars clump together like that? First of all? And what makes a galaxy special?
Like?
Why is it more than just a clump of stars?
Well, what makes our galaxy special is that you're in it. Horse, there's no other galaxy that feature is such a good looking, funny.
Cartoonist me and lentils. We make it. We make it habitable.
Right, Okay, so what's the recipe for a galaxy? Right? Well, the thing that the galaxies have the most of, remember, is dark matter. In general, there's about five times as much dark matter as there is any other kind of matter, you know, the stuff that makes up gas and dust and stars and people and cartoonists and ice cream. So it's mostly dark matter.
So that's the stuff we can see or touch. I mean, we did a whole podcast episode on dark matter, but it just in case somebody didn't listen to it. It's like this weird invisible dark gravity thing. That's hanging out that every galaxy has.
That's right. Yeah, we call it dark and matter because we can't see it, so it's dark and we know it gives gravity, so therefore it's matter. And the crazy thing is that until you know, a few decades ago, we didn't even know it existed, and now we know that galaxies are mostly made up of this stuff. Right. Wow, So number one ingredient when you want to make a galaxy is you have to have dark matter.
It's like five times more than the star, right, yeah, exactly, Like a galaxy is basically a clump of dark matter with a few sprinkles of stars in it.
That's right. Yeah. If a galaxy was a cupcake, right, the dark matter would be the chocolate cake, and you know there everything else would be the frosting and the sprinkles. The gas in the dust would be the frosting, the stars would be the sprinkles on top.
Oh I see, okay, that's kind of the right proportions.
Yeah, something like that.
Wow.
So you start with a big blob of dark matter, okay, and that's most of it, and then after that you have huge amounts of gas and dust, right, and that's the stuff that's left over from the Big Bang or left over from stars exploding, and those are the ingredients you need to make planets and stars and all sorts of stuff that you're familiar with, right, And so you have dark matter, you have gas, you have dust, you have planets and stars.
And black holes. Right, Like there's just little black holes sprinkled throughout probably, but there's a huge giant black hole at the center of every galaxy.
That's right. I can't believe I forgot the black hole. The black hole at the center of almost every galaxy is huge. It's like, you know, millions of solar masses and it's sitting there at the center of the black hole, and it's it's got a lot of stuff to it also, right, it carries a lot of mass and so it contributes. So that's what a galaxy is. And you know, a galaxy couldn't really form without all those elements, Like you couldn't really have a galaxy without dark matter because dark matter provides the gravitational traction to suck all this stuff together. You know, they do these simulations of the universe and they say, what would the universe look like if you never had dark matter? In it, and it would take a lot longer for galaxies to form because dark matter has pulled all this stuff together. It's like it's made a you know, like a well in the rubber sheet of the universe, so everything rolls together more closely.
Hmm, Okay, so that's that's a galaxy. It's a black hole surrounded by dark matter and.
Sprinkles of stars and gas and dust and lentils and lentals exactly yes.
And so they're not just hanging out in space. They're moving around.
That's right there. Each one is spinning, right, which is why you see a lot of them having these spiral features. Each one is spinning, and then they're also moving around each other. They have gravity and they're moving around each other, and they have these Each galaxy is a member of a cluster of galaxies, and so these guys are orbiting the center of the cluster. And then the clusters are members of superclusters. So these things have a lot of gravitational interactions everywhere.
It's like a system of galaxies. They all interact with each other, and they're all spin around their common center of mass.
Exactly right, And they're all spinning around that center so it's sort of like a big slow motion tornado, right you looked at it, If you looked at it really really slow, you're like, oh, nothing's really moving. I mean, I guess a little bit. But you watch it at natural speed a tornado, and obviously it's going really fast. And so a galaxy is that's sort of that same way. The gather system of galaxies is sort of that same way. Right, They're all moving around each other and then occasionally, you know, they bump into each other.
Wow, that's so weird to think that gravity works that way. Like we are, you know, moving around the center of the Earth. The Earth is moving around our solar system, around the center of gravity, which is mostly the Sun. But the Sun is awesome, moving around the center of gravity of the galaxy, and the galaxy is also moving around the center of gravity of its cluster of galaxies.
That's right. Yeah, and on and on and on like a bunch of nested Russian dolls, you know, Yeah, until you get to the biggest structures in the universe, you know, which are the superclusters, and then the filaments of superclusters, and beyond that, we don't know anything about whether there are bigger and bigger structures. That's as far as we've seen.
So we're moving around, and sometimes these two galaxies can just run into each other. In the giant fastness with space, all these moving galaxies can sometimes cross paths, right.
Yeah, And there's another thing I want to say about that before we talk about what actually happens, which is that it's incredible to me that gravity is the force that's dominant on these scales, right, Like, that's the thing that's controlling how galaxies form and how they dance around each other, and that's pulling them all the way through the universe and forming these crazy structures. It's all gravity, right. But gravity is the weakest force nature. It's weaker than electromagnetism, it's weaker than any of the nuclear forces. It's pathetically weak, but it's the only one that operates on these huge scales, and it can't be balanced out. And so because it's only an attractive force, it's no repulsive version of it. And so that's why, like on these huge scales, gravity is a thing that dominates. Gravity determines the structure the Solar system, the structure the galaxy, the structure of the clusters, gravity sort of wins in the end. It's like, you know, Revenge of the Nerd Forces, right, It's like the weakest force in the end controls the universe.
It's like slow and steady wins the race.
It's the turtle forces. Yeah, anyway, we need to do a whole other podcast on why gravity is so weird and weak and whatever, and we're get to that.
Okay, So we have a clusters and galaxies are moving around space and some things they collide. So yeah, let's talk about what actually happens when two of these things collide. But first, let's take a quick break.
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All right, so we're sitting in a galaxy and we are moving inside of this galaxy, and this galaxy is moving in space. But there's another galaxy nearby called the Andromeda galaxy, and it's kind of an intercept course with us, right, like we're going to run into it in about four and a half billion years.
Yeah, that kind of they've measured it. They can measure the velocity of Andromeda relative to us, and they can see that it's getting closer and closer every year, and they can also measure the lateral velocity, like is it gonna shoot by us or just or come right at us? And after for a while they weren't sure. They were like, oh, it's head and our way, but it could miss, you know, like every time they say there's an asteroid coming within, you know, a certain thousands of miles of the Earth, and the usually it misses. For a while, they weren't sure, But now they're pretty certain. They've taken enough measurements, they've seen it move, and they can project confidently that these two things are gonna collide. Also, Andromeda and Milky we have a lot of gravity and so you don't have to aim perfectly to get a collision right. They're gonna pull each other closer and closer.
They want to collide, you know, do you know what I mean? Like, it's not like a random asteroid, It's like we're pulling towards each other.
Yeah. Well, I don't know if you can really say they want like you understand the psychology of a galaxy. Do you know what galaxy wants in life?
You know, hey, galaxy feelings?
Right?
I think I read that science fiction novel right where every galaxy is actually a living thing and we were just like the tiny mote on on an island of red blood cells inside a galaxy. Anyway. Yeah, so you don't have to shoot perfectly, and they're going to collide. So to think about what happens in the collision, you probably think about each individual piece separately.
Like we're a cluster of things, Like a galaxy is not a solid object, it's like a word almost like a cloud of things, right, is that kind of what you mean?
Yeah? Yeah, exactly. And you know, imagine two crowds right passing into each other, and like one gets off the train and one's coming down the stairs and they pass each other on the platform. What's going to happen, Well, it depends on how they interact, right, and how dense they are. Oh, so we can start with something on the obvious parts, like the stars. Okay, so you might think, oh my gosh, there's one hundred billion stars come and right at us. That's going to be a big deal.
Is that the right size? Like it isn't dramata about the same size as the Milky Way.
Actually I think it's bigger than the Milky Way. But you know, factors of ten yere are not important. So it's hundreds of billions of stars. And each star, of course is really big. And you might think, well, they're head and right at us. You know this is going to be a big deal, But remember that the stars are really far apart. Also, like galaxies are huge, not just in terms of the number of stars, but in terms of the amount of space they take up. Oh I see, and you know you look around you in our galaxy, there aren't that many stars nearby, right, and the closest stars are light years away.
I like this crowd analogy that's pretty interesting. Like we're a crowd of people getting off the subway. There's a crowd of people coming down the stairs to get on the subway. It's going to be a disaster potentially.
Potentially, But if it's not rush hour and the crowds are pretty light, you know, there's like enough space the two crowds can just pass right through each other.
Like if the stairways and the hallways are huge and people are pretty spread out, it may not be like a riot, you know, it may just be like a busy intersection.
Right, It's like two people leaving Yankee Stadium at the same time as somebody else is trying to come in. Like there's plenty of exits. Nobody's going to bump into each other. Right. Oh okay, and that's sort of the case with stars. I read this one comparison where if you imagine a star is the size of a pingpong ball, on average, the nearest star is three kilometers away, right, So like if you were going to throw a ping pong ball into a cloud of ping pong balls where the spaces between them were three kilometers away, you'd be lucky if you hit anything, right, even if you were trying.
Oh I see, okay, So our galaxy is actually pretty sparse, meaning the stars are pretty far apart from each other. We're not sort of clumped together. Yeah, exactly and astronomically speaking.
Astronomically speaking, and so there's going to be very few or probably zero direct collisions, you know, where one star like actually slams into another one, you get stellar explosions. I mean, that would be pretty awesome. I would pay for front road seats for sure, But I think it's pretty unlikely that's going to happen.
Oh but you know, there's one hundred billion stars running into one hundred billion other stars. Surely some of them are going to hit head on, isn't it. Aren't they?
I mean, there's always a non zero probability, and you could get lucky or unlucky, depending on which outcome you're rooting for. But if they're diffuse enough, right, they're far enough apart, then then all of them could pass through without hitting. I mean, I think probably the most likely scenario is that maybe you get one. The stars also don't have to hit directly to affect each other, right, each one is a big blob of mass, which means it has gravity, and so they can jostle each other. I mean, if another star came by near our solar system and pass nearby, it could affect the orbits of all the planets nudge a planet out of orbit. It didn't have to hit the star directly head on in order to affect our lives.
It could maybe pull us out of orbit or suck us into that other star.
That's right. It could steal planets, right exactly. Or one of our planets could get ejected out of the Solar System right, or it could even kick our star out of the galaxy. Our star is in orbit around the center of the galaxy, right, and if it comes, if another star comes near enough, it could get pulled and so that it gets out of that orbit. An orbit is sort of a delicate thing. It had to be the right radius and the right velocity for it all to work. Start going too fast and you reach escape velocity, and our star could even get kicked out of the galaxy. So we could be you know, sort of evicted from the Milky Way, floating in intergalactic space, just our star with the planets and everything.
Oh I see. So when two galaxies collide, we don't have to worry about things running into each other. But it is going to be pretty chaotic, right, Like, suddenly there's going to be you know, twice a number of stars and that's just going to change everything.
Right, Yeah, exactly, So things are definitely going to get mixed up. The stars won't necessarily smash into each other, but they definitely mix each other up and disturb each other. Yeah.
So are they are these two messages just going to kind of go towards each other, mix a little bit and then keep going. Or are they you know, slamming to each other and then become this giant mega galaxy.
It depends a little bit on their relative velocity. If they're going fast enough relative to each other, then they'll pass through each other, right, But if if they're not, it doesn't seem like they are that The most like scenario is that they merge, that they come together and there's a little bit of sloshing and whatever, but eventually becomes one big galaxy.
Wait, what does that mean? It's like the the other stars and from the other galaxy they're gonna come, but then they're gonna kind of go pass us a little bit, and then they're gonna get pulled back in kind of thing like it's gonna like a giant jelly out in space, Like it's gonna go move, you know what I mean.
But in slow motion, Yeah, or sort of like things getting flushed down the toilet. You know, they come closer and closer and closer and circle each other faster and faster. Oh sorely.
You know, we might circle each other, the two galaxies.
Yeah, and sort of a while being on top of each other, you know, so come together, pass a little. The centers of mass might pass a little bit and then turn and come the other direction and spin it faster and faster until the center is a mass aligne.
So being flushed down the toilet. That doesn't that doesn't sound pleasant. Like, that doesn't sound like it's going to be easy, do you know what I mean? Like, it doesn't sound like it's gonna uh leave us unscathed.
It might, though, you know, our sun could be totally fine, and it could be that the planets are not distorted, their orbits are not distorted, and we could just have a front row seat to a pretty amazing event. And the other thing is that we see this happening all the time. Like you look out into space with the hubble and you zoom in on other galaxies. There's lots of galaxies out there, and lots of them are in various stages of merging, and you can see galaxies that are just starting to merge. You can see galaxies that have been merging for a billion years. You can see galaxies that obviously merged a long time ago. And there's sort of like an uncomfortable blob of two galaxies, like one spiral arm sort of knocked off over here and there's another one over there. And so we have a lot of catalogs of examples of galaxies that have merged. That's how we know so much about it.
Yeah, if you look at there's a bunch of crashes that you can study.
Yeah, exactly. So you want to know what galaxy collisions look like, you don't have to build a galaxy collider. This is one thing I love about astronomy.
You just have to google.
You can just that's right, cosmic googling, otherwise known as telescopes. You just look out into space and eventually you will see that thing happening, like you want to imagine some crazy scenario, or this kind of galaxy hits that kind of galaxy, and then from behind comes a third one that's happening somewhere out there, and you just need to find it and watch it. And so That's the amazing thing about astronomy is that all these cosmic experiments are happening. We just need to look for them.
Wow, okay, well we process. That's say, let's take a quick break.
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All Right, so that's what might happen to the stars in the galaxy. What's going to happen to all these other parts of the galaxy when these two galaxies collide?
Right? And I like that we started with the stars because that's like the most important thing to us, because we're sort of starrocentric, right, because we think stars are the most important element of the galaxy. But the biggest element of the galaxy, remember, is dark matter. And so you might ask, well, what's going to happen to all our dark matter? And just like with the stars, what happens there depends on how much it interacts. Currently, we don't really know anything about how much dark matter interacts. We know that it doesn't interact with normal matter, we think it doesn't interact with itself, or if it does, it doesn't interact very strongly and so, but it does have gravitational attraction. So if the galaxies are going to hit each other and they're not moving too fast that they just basically pass right through each other, then the gravity from dark matter is going to affect the gravity from the other galaxies dark matter just the same way the stars are, and the two will sort of merge eventually become one big dark matter halo. And it's the kind of thing I would love to watch, but you can't really see the dark matter.
It could be just another version of the cluster of stars. You know. It's like one blob goes into the other blog and then they kind of slush around and then just becomes a bigger blob.
Yeah, you can think of the stars. It's sort of like a collisionless liquid, right, It's like a you have a liquid of stars that don't interact with each other the same way the dark matter does. So dark matter and stars are basically operating this under the same principles. The only relation of ant interaction that we know about is gravity. So everything we said about stars is also going to affect the big blobs of dark matter. Now, dark matter is much more continuous. We think it's smooth. It's not like there's just dots of it here and there. But because it how hardly interacts with each other, it doesn't matter if it rams smack into itself. Right, It mainly effect is gravitational.
It may not interact with itself, meaning it could just pass by itself and not really kind of explode or collide or do anything besides pull itself gravitationally.
Yeah, exactly. And we don't even know what dark matter is made at us. We can't say things like dark manner particles can do this. Dark matter as far as we know, it's just smooth, collisionless blob of something. And we know it has gravitational interactions and that's really about all we know about it. So we think that that that's what's going to happen. And you know, we've seen dark matter in these gravitational collisions and we see that it basically sticks with the galaxies, right, it sticks with the stars.
Okay, so then the last part is the black hole at the center of each galaxy.
What no, no, don't forget the dust, right, this gas or dust, which a lot of people overlook. And this is actually the most exciting part because.
The dust is the most is the coolest part.
That's how you know you're listening to a nerdy podcast and they get excited about dust. Oh my god, the dust.
You know.
If for those people who are like expecting dramatic events and explosions, this is where you get them. Okay, because dust is not diffuse, right, It's spread everywhere, Like you have a big blob of dust. It's not like little clusters of mass the way stars are. It's a huge extended blob of dust. And when it smashes into another blob of dust, you're gonna get fireworks. Like those clouds of dust interact with each other the way dark matter doesn't, and they're spread everywhere the way stars aren't, and so you get huge collisions. And what happens when you compress gas and dust. What happens when you collide huge blobs of gas and dust is you get more dense and then you get stars. And so you could see like new stars being born where these two huge clouds of gas and dust bang into.
Each other literally like fireworks.
Like that's right, Cosmic fireworks. I mean, what's more dramatic, and then what's a better cosmic fireworks than seeing stars be born?
Yeah, so this one is going to be like too, you know, you know, two liquids kind of running into each other. It's going to be kind of dramatic. You know, it's going to be like with the sound effects and everything in space.
No, yeah, exactly, It's just like two water balloons hitting each other. Right, You're gonna get an initial shockwave. And you know you don't get stars born when you fire water balloons at each other because the density isn't good enough obviously, But yeah, you're gonna get a shock wave, you're gonna get friction between the fluids, and you're gonna get stars being born. It's gonna be pretty dramatic. So you don't want to be there.
You don't want to want to But we are, aren't We surrounded by gas clouds and stuff?
Oh? I think you need denser stuff. I mean, the Milky Way definitely has big clouds of gas and dust.
Oh I see, But when those clouds run into the other clouds, then that's where this stuff happen. But we're not necessarily sitting in one of those clouds.
That's right, Yeah, Okay, the last element is the black hole, right, and so our galaxy is a huge black hole in the center, and the other almost every other galaxy is a huge black hole in the center, and there it's going to be mostly dominated by gravity, right, because they're going to pull each on each other really hard, and they're going to pass by each other a little bit, perhaps because they probably not it can hit dead on, and then they're gonna swing around. They're going to pull on each other, so they'll probably be you know, some sort of a near miss, and then they'll turn around and come back, and then they'll just circle each other faster and faster and faster. And if you remember the episode we did on gravitational waves, or if you've heard about the discovery of gravitational waves, you know that what happens when black holes get close to each other is they start to circle each other faster and faster, until eventually they spin really really fast and the distance gets closer and closer and closer, and then they merge and they become one enormous black hole. They like eat each other.
Right, And it's not a peaceful event. It's like a pretty violent thing, right, Like they've been super super fast. There's energy spewed out everywhere, and then suddenly you have these huge, cataclysmic gravitational waves.
Oh yeah, when black holes fight, it's a big mess. Absolutely. You don't want to be anywhere near that, wow, because huge amounts of radiation, not just gravitational waves. Right, yeah, you make gravitational waves, which are pretty awesome from a physics point of view, but you know, these things tear up into each other and emit huge amounts of radiation, and so you don't want to be anywhere near that. Yeah. I mean that's going to like sterilize life on any nearby star system for sure. But anyway, there probably isn't any life in the center of the Heart galaxy for that same reason that the galactic black hole is already emitting huge amounts of life killing radiation, so you don't want to get too close anyway.
It's like the eye of a storm. There's nothing living in the middle of it.
That's right, right. I don't know if it's calm inside the black hole, though. We did a whole episode actually on what it's like to be inside a black hole. So you guys should go listen to that. But yeah, everything is swirling around that central black hole, and so probably what will happen is they'll merge and the new milk the new galaxy. I wonder what that galaxy would be called. Actually, how would you combine Andromeda and the Milky Way like Drama Way, milk milk Drameda, I don't know, andromedaway, the Andromeda away. There you go, the Andromeda away. Yeah. The the new galaxy would have a huge, super duper massive black hole at its center, and so I think that basically sums it up. You'd have the black holes will probably emerge huge violent eruption of radiation there. The gas and the dust would have a lot of friction. It caused, caused star formation.
Big explosion, big explosion works, Yeah, exactly.
Friction, Yeah, just all the kind of stuff you expect to see in the next Transformers movie. And then stuff. He'll be there everything. If there's some money to be made, he'll be there. And then the stars and the and the dark matter will just have a gravitational effect, but they'll, you know, eventually settle down and in a few more billion years, the new galaxy will have its own shape. It will sort of settle into its own new shape.
But it kind of sounds like every part will do something different, do you know what I mean?
Yeah, they will because they follow different rules, right, they'll interact differently and so.
But so then kind of the nice structure we have now is going to be pretty much obliterated right when it merges with the other one.
Yeah, exactly. You shouldn't count on your real estate being the same value after the galaxy collision. Everything's going to be shook up, right, absolutely.
So it's going to be disrupt The entire both galaxies is going to be totally disrupted fireworks collisions. But you're saying it's possible we may survive it, right, Like it's possible nothing will actually happen to our Solar system.
I think that's the most likely outcome. Yeah, is it will just be sort of interesting, slightly, Yeah, most likely most likely thing. I mean, we're a star, We're basically part of our star, right you think of the Solar system as just one big blob, And the most likely thing is that nothing gets close enough to disrupt our orbit around the star. And you know what, even if our star gets like ejected from the galaxy, so what we don't need the galaxy. We could live just fine, just a star with a bunch of planets in the middle of intergalactic space. We don't need anything else. We just never start to provide energy for life, so so we don't I mean, just in the same way we're talking about the beginning of the episode, like you don't really notice what's going out in space because you don't usually have to. And if all those if all those stars disappeared and all we and we were in the middle of intergalactic space, it wouldn't change your life at all. You would still still need to stock up on lentils for the coming apocalypse. You know, it wouldn't save you or change your plans at all.
You wouldn't mind getting kicked out of town like that. That's kind of what it would feel.
Like, Like that's the right excell The whole town, our whole town would just get kicked out, you know, and we just go on living the way we did before. But things will definitely change for us even if we survived it's galactic collision, the night sky will look very different. I mean, as Andromeda approaches in the next few billion years, it will grow in the sky and eventually look really big. And then after the collision, right when things have settled down, the night sky will look totally different. All the stars will have been rearranged, and we won't see that band in the Milky Way anymore.
Well, that makes me feel better. I was sweating. I was sweating what was going to happen for and a have billion years from now. But now now I feel better, and I hope Blake you also feel a little bit better.
Yeah, that's right, Blake, chill out, don't worry about it. You have nothing to worry about to work. I think it's fun to think about things happening deep into the future, and also even further into the future. You know, the the universe has been around fourteen billion years, right, and that's just sort of like the initial bits now before we get to the interesting part. But it could be that we're not even at the interesting part.
You know.
Thinking about galaxies in this way reminds you that they're spinning their dynamic, they're swirling around each other. What's going to happen? We don't know, right, they could continue to swirl and form crazy new structures that know, the universe has never seen before because there hasn't been time to make them. And so this is the kind of thing makes me think about the universe, like on the trillion in your two trillion life year cycle, Like if life is still around ten trillion years into the history of the universe, they'll think about these first few moments of galactic formation as you know, almost irrelevant or just like just warming up.
Yeah, the best maybe yet to come.
Now, that's right. I'm an optimistic person, so I'm always hoping that the best thing is yet to come.
Exactly well, great, Thank you so much, Blake for sending us this question. We really enjoyed answering it.
That's right. And check out our book called We Have No Idea. It's a guide to the unknown questions of the universe, all the things that physics wants to know the answer to but really hasn't got a clue about. And thanks for listening.
Yeah, and if you're hungry or want to stuck up, just don't forget to get Daniel's Spicy lentils, now available at your local grocery store.
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