Can you roast a marshmallow in space, and other listener questions.

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Speaker 1: Hey, or Hey, I have an important star geasing question for you. Hit me so obviously, to fortify yourself for a cold night of dark sky watching, everyone needs to make s'mores on the campfire after dinner. Is that any mean a question? It's a s'mores are required when you go camping. Yeah. Absolutely, But my question is how do you like your marshmallows? You like them white, gently toasted, or totally blackened? Because I'm pretty picking about my smores. They need to be like just slightly toasted. But mostly I just want more of them. I should have known the marshmallow jokes. We're going to make for a rocking road that makes more of them. Hi'm orhand make cartoonists and the creator of PhD comics. Hi. I'm Daniel. I'm a particle physicist and a professor at U c Irvine, and I have strong opinions about marshmallow tisting. Interesting. Is there a special physics technique to make perfect moores? You have to keep at exactly the right distance for exactly the right time, and any deviation from that results in inedible garbage. Interesting? And I guess you have to rotate it too. That's very important, you know, experimentally determined rotation rate. Did you rotate your marshmallows at and did you hook up some kind of motor to it so it's always precisely the same. I will say I have done a lot of extensive experimentation on this front. You know, for science, you have a lot of data points in your stomach and around your waist. That's exactly My data collection device gets bigger and bigger as I keep taking more data. But welcome to a podcast. Daniel and Jorge Explain the Universe, a production of My Heart Radio in which we twist and turn the entire universe around, trying to understand exactly the right distance to look at it. So that makes some sense. We ask the biggest, the deepest, the squishiest, the tastiest, the toastiest of questions about the nature of the universe. What's in it? How big is it? And how can we possibly understand it? Yeah, because it's important to understand the universe, not too much so that it gets toasted, but not too little so that it's too hard. And the chalk that doesn't melt. You think it's possible to understand the universe too much like we ruined the mystery. It's no fun anymore. Yeah, you know, it's sort of like knowing too much about a movie before you go in. It's hard to enjoy it, you know. Or it's like knowing too much about writing, and then you can't enjoy a book or a TV show anymore. Oh man, give me all the physics spoilers. I want to know them. I'm happy to have all these surprises being ruined. I don't want to hear about the next year's Nobel Prize. I want to know about it now. But then you're gonna spoil it for everybody else. Isn't that the whole point of physics to disseminate the knowledge and spoil it for everyone that's in the clubhouse plaque? Right? That is part of it. But you know, I think that it's impossible to know the universe too well because I think, honestly jokes aside, there's an infinite amount of things to know. I think we will never know everything about the universe. They will always be more marshmallows to toast and more physics puzzles to unravel. Maybe you should preface every research paper you published, but that you know, warning spoilers ahead. Finding the spoilers is exactly the job of physics, right, Physics is basically the spoilers. Or maybe we should just like figure out the universe and very slowly dull it out, you know. We should talk to the Marvel folks and like have plot twists and stuff like that. Yeah, and sequels, lots of sequels, that's important. And multiverses. I guess now that's the thing. Yeah, I would definitely like sequels and multiverses for my funding. I guess if you spoil one universe, it's always more universes. Technically to watch movies right with different actors. There's an infinite audience out there and an infinite possible box office infinite spoiling war. It will be the name of the big culmination movie Marvel. We get a cut of that one one millions of infinity. But it is an amazing universe, a delicious universe, and an incredible universe to think about and to ask questions about it, and especially to be curious about. That's right. And it's not just academic physicists who are toasting marshmallows and thinking deep thoughts under dark skies while on camping trips. It's everybody out there who looks up at the night sky and wonders what's going on around that start is there an alien looking back at me? Or what's the physics of this marshmallow? How is it really getting roasty and toasty? Everybody out there who is curious about the universe is doing physics and being a physicist, that's right. We get questions on this podcast from little kids from seven years old to seventy seven year old who look at the universe and wonder how it all works and what makes it the way it is. And we love that because we think that being curious is part of being human and that science belongs to everybody. So if you're the kind of person who thinks about the universe and wonders how things work, then right to us, please send us your questions. Don't feel alone, we are all sharing these mysteries together. Right to us too, two questions at Daniel and Jorgey dot com. We answer every email. We right back to everybody. And let me send a special encouragement to those of you who have been listening to the podcast for years and haven't written to us yet. I know you have questions and we'd love to answer them. It sounds like you're scraping to the bottom of the barrel now, Daniel. But actually you get a ton of questions every day. You get questions every day through Twitter, through email, and also through our discord channel. We have a discord channel. That's what it's called, right, That's what my fourteen year old tells me. It's called a discord server. I think it's called Yeah, it's not a discord TikTok or something. Yeah, exactly. We interact with people on Twitter. We answer dozens of questions over email, and on discord. We have a community not just me answering questions, but other listeners talking about cool things they've read, interesting stuff they've seen, and talking about the episodes, asking questions about things they heard. So please come interact. You're not out there alone wondering about the universe. Well, have you gotten listeners to answer their own questions? Like one listener aswers the question of another listener sounds like you might, you know, put us out of the job here. That's exactly what happens. You know, somebody asked a question like two am, and then by the time I log on at seven am or so, there's a whole discussion and people proposing answers, and it's a lot of fun. Obviously, you need to stay up all night every night on Discord, just like your fourteen year old son. Yeah, exactly. Maybe we should work in shifts euro Upe that time. Anyway, Yeah, there you go. But yeah, we do get a lot of amazing questions because people are curious. They look at the world, they listen to this podcast. They hear about things happening out there in the cosmos and the very nature of our atoms and courts, and the questions come up. Questions do come up, and they send them to us. And sometimes those questions are so fun that I think other listeners would like to hear the answers that we pick a few of them and answer them right here on the podcast. And so today on the podcast, we'll be tackling listener questions number twenty four or is that like the TV show twenty four? Are we going to talk about, you know, nuclear bombs? And if we don't answer it, something terrible's going to happen. I don't know which one of us is, Jack Bauer. Are you going to torture physics answers out of me? Torturing physicists. That might make a good show. I hope it doesn't get a big audience. Who wants to see a physicist suffered? Come on, that's right? Yeah, physics our self torturing anyways, exactly why else would you choose that career if not to torture yourself? Otherwise we just would have been a cartoonist, you know, easy, laid back, no stress career. That's right, Eat cereal at eleven am. You put on your earphones and you you hop on a podcast. Yeah, twice a week, easy living. I do get risk cramps though, that is the one hazard in the job. Also, your pajama pants and sometimes get a little bit cheap, but you know you have to remember to change them. So are you ambidextrics? Can you switch to the other wrist when you know the right wrist runs out of good jokes? You know? I just turned my computer around. I don't know how that works. You're the physicist, OK, yeah, I think you just violated parody symmetry. Did you just say I violated parrot tree? Did? Yeah? The parents are very upset about their tree. I flipped their tree. Yeah. This is the twenty four episode in which we answer listener questions, and so people send us questions and how does it work down and you ask them to record it and then send it to us. Yeah, if there's a question I think will work well on the podcast, I ask them to just record themselves at home. They use the phone, to use their computer, they use whatever they have, and they just email it to us. And so it's very easy, no big deal. And so that's why we get this fun audio from listeners all around the world with cool accents. Yeah, very cool. And so today we'll be answering three pretty awesome questions from listeners, and they're pretty exciting and kind of delicious as well to think about. One of them is about roasting marshmallows in space, the other one is about the impending collision of our galaxy with another galaxy. And the last one is about I guess what would you call that space rain? Dangerous space rain? About how to survive the cosmic weather between here and other stars. Interesting. I guess if you're roasting marshmallows out there, you want to be safe as well. You don't want to be extra crunchy, that's right. So we have deep questions about the future of our galaxy and practical questions about how to roast marshmallows. All right, well, let's tackle our first question, and this one comes from Aiden, who is a question about eating snacks. I was wondering how close would you need to get to the sun to safely roast a marshmallow, or basically, how close could a single person get to the sun and be safe, or how much closer to the Sun would the Earth need to move for humans to even notice a difference. Thanks, all right, thank you, Aiden. And I'm a little confused he sort of posted the same question in three totally different ways, I feel. I think his question is trying to understand sort of the temperature things get when you get closer or further from the Sun, because you know, the Earth is sort of like at the perfect temperature for water to be liquid on the surface and for humans to have like nice relaxing vacations in Haaii and not get too hot, but if we were any closer, things would get a little toastier. And so I think he's really asking about, like, what is the temperature gradient? You know, how close do you have to get to the Sun before things get uncomfortable? I see, well, he painted a picture of roasting marshmallows in space. So I guess I'm picturing Aiden in a spacesuit holding a stick with a marshmallow on it, and is he wondering like how close does he have to get to roast the marshmallow or how close can you get without you know, burning up? Yeah, it's a good question because he's using the marshmallow as a probe, right, like what happens to the marshmallow? Is it going to survive? The problem is that if the marshmallow gets toasted, he's probably also getting toasted because you know, unlike a fire, if you're near a fire, then the temperature drops off really quickly. So you know, you can have the marshmallow be a foot or too closer to the fire than you are and it'll get toasted and you won't. But when it comes to the sun, the temperature drop off is you know, over a much larger scale, and so if the marshmallows a foot closer to the sun than you are, you're probably getting just as toasted as the marshmallow. I see, unless I guess you have some kind of shielding, special shielding, like what if it's he's behind like a big shield with a little hole that you can stick the marshmallow through so that it gets roasted by the sun, but not yeah, or his stick is like really really long. That's a good physics solution there. Just make a roasting stick that's you know, three hundred thousand miles long. Yeah, exactly. I just ponwned off the problem to the engineers, like, please, you know, send me three prototypes by tomorrow. Yeah, just don't make it out of chocolate. That would defeat the purpose, like a chocolate cover roasting thick. I'm gonna write that down, Daniel, that's my next pat Okay, Yeah, I wonder how many of those will actually make it out of the lab or you know, well, I made it three hundred kilometers long, but it seems to have been chewed on. That's right, and I had a heart attack before it could write the pen. But I think there's actually two interesting questions here about roasting this marshmallow in space, assuming that aiden can somehow get to a safety ins or has shielding, and you know, one is like what happens to a marshmallow when you put it out in vacuum? And the other is then how close do you have to bring it to the Sun to get it toasted. I see you're thinking, like maybe let's just send the marshmallow by itself, Like let's throw it into orbit around the Sun, and when it comes back it'll be nice and toasting. Yeah, But also I'm wondering, like, well, listening actually be edible. If you put a marshmallow into outer space, it might like explode, right because of the internal pressure. And so then even if it is toasted, is aiden really gonna want to eat it? I mean, I just want to deliver to our listeners the treat that they're looking for. It sounds like you just said like that the marshmallow would explode or get bigger, which all both of them sound good, But you're not going to get more marshmallow, right, be the same marshmallows, just less dense. The idea, of course, is that marshmallows have air bubbles inside them. The way you make a marshmallows, if you whip up all this fat and this sugar and so it's really like a little froth. It's like a big foam. And so we take that into outer space, it might just explode because all those air bubbles no longer have air pressing on them from the outside. Interesting. But wait, is a marshmallow like a sponge or does it actually have air trapped inside? You know, like a sponge you can squeeze and and somehow all the holes are connected to each other. Right, it's a really good question. You know. I think that there is some air trapped inside this marshmallow. So I actually went and did some research. And there's a physicist at you see, Santa Barbara that did this experiment. He took a marshmallow and he put it in a vacuum chamber. So it's kind of vacuum chamber in his lab, probably for other real physics reasons, probably cause a few million dollars, but funded by the NSFU, Yeah, probably exactly. I mean the National Snack Foundation for Research and Snack Physics. Yeah, yeah, not to be confused with the nih which is the National Imbibing Headquarters in the National Indigested Headquarters. Well, he took some marshmallows and put them in a bell jar of vacuum chamber, and the marshmallow expanded to about twice its normal size, And so that suggests that there is some air trapped in there. And if you reduce the pressure on the outside of a marsh it really will inflate. Wow, did he or she polished these results just on a blog? So this is not a peer reviewed right, you know, so take it with the grain of salt people, right, or as a piece of chocolate. But there's another question, because the vacuum of space, of course, is much much colder than the atmosphere in this lab, and so you might also imagine that the marshmallow might flash freeze, in which case it wouldn't expand. It might freeze first and then the air would sort of leak out through cracks. And so it wasn't exactly clear what would happen in that case. They need to do more experiments, which also, you know, thinking about it, sounds like exactly the kind of research that goes on in the place like did you see Santa Barbara. Oh, they followed up more experiments. They took the marshmallow and dipped in liquid nitrogen and then put it in the vacuum chamber, and it didn't expand as much. And so you know, that's not exactly what would happen in space. But I think it's a pretty good proxy, and so I think this marshmallow before it gets toasted, is going to puff up a little bit, but still be recognizably marshmallowy. I see, But then as you get closer to the Sun, it's going to heat up. Then it's gonna heat up exactly. So then then it might expand to twice its size. Yes, because as marshmallows heat up, they do expand, right, because the error that's trapped inside them gains in pressure and volume. So it might not explode. Or maybe it depends on how quickly you put it in a vacuum too. So then you put this marshmallow out in space, it expands, and then how close do you have to be to the Sun before you can it gets nice and toasty. It's a good question, and you have to make some assumptions here about how you're going to heat the marshmallow, because there's some subtleties like if you take an object and you put it at the same distance from the Sun as the Earth, it'll get heated to about five celsius. So that's like, you know, forty five or so degrees fahrenheit just from being out in space, just from being out in space and getting radiation from the Sun. And that's assuming that it gets thermalized. That like, the energy coming on one side goes through the object and heats up also the other side of the object, and it goes into sort of thermal equilibrium. That's not true. For example, of the Moon. The Moon is an object, you know, very similar in distance as the Earth from the Sun, but it gets very very hot on one side and cold on the other side because it doesn't normalize. Like the Moon gets more than a hundred C on one side and it's very very cold on the other side because the heat is all trapped on one side doesn't like bleed all the way through the Moon. So if we're talking about a smaller object, we're not just that's like spinning, so the heat gets evenly through it. Then something at the distance of the Earth gets to about five C. I say, thinking about kind of the physics, I guess, you know, it's getting all this radiation and energy from the Sun on one side, but I guess all around it, it's still in a vacuum and a really cold vacuum, and so it's shooting off heat in all directions. Right, it's like just trying to get cold. But then it also has this source of energy from the Sun and so you're saying, at some point, maybe it gets to it clirium and it gets to an even temperature. Yeah, and things here on Earth they also cool off. Right, you have something really hot, like a pie, you put it on your counter, it's going to cool off. That happens mostly because the heat is diffusing. It's the molecules of the pie are bumping up against the air molecule and they're warming them up, and then that air gets pushed away and you get new cold air. There's another mechanism for cooling, which is that you can just radiate off heat. Like things that are hot get red hot or white hot, they glow. They give off heat through radiation, and so in space you don't have air to cool things down, but you can still radiate heat. So things cool down slower in space than they do on Earth. It's harder to lose your heat in space than it is here on Earth because there's no air, no wind basically to cool you down. But you're exactly right. We're talking to hear about an object that comes into thermal equilibrium, where it's gaining energy from the Sun and radiating some energy away, but it comes into equilibrium, And so what that equilibrium temperature is depends on how close you are to the Sun. If you're very, very close to the surface of the Sun, you're gonna be basically at the Sun's surface temperature, which is like thousands of degrees. And if you're out where the Earth is, you'll be around five degrees celsius. But I guess the question is, you know, at what point will it get toasty? You know, like if it's facing the Sun and you get close to it, I would imagine that at some point the side of the marshmallow facing the Sun is going to start to melt, maybe and maybe even toast. Yeah, And so I did a little calculation using stuff on Boltzimann approximation, etcetera. And I'm figuring that you need the marshmallow to get to be about fifty c in order to toast, in order to melt, which is a temperature with the marshmallow melts, And in order to get to that temperature, you need to be about point four a U. So of the distance between the Earth and the Sun is a temperature where an object will get to fifty c in equilibrium somewhere between Venus and mercury. I see, that's an equilibrient meaning I guess if you're constantly rotating your marshmallow, or you give it a little bit of a spin in space before you throw it out there, it might reach some sort of equiproum, right, because it's going to be you know, kind of basting calm almost rotisserie marshmallow solar rotisserie. Right, that's really what you're doing when you're rotating the steak. Right, Yeah, that's right, the poor man's rotissory. And so that's assuming that it's spins it's equally distributed. If it's not, then one side of it will get hotter. So, for example, if you have a marshmallow at that's just stationary and all the energy is going to the surface of the marshmallow, then it's going to be like the Moon where it gets really hot on one side even at our distance. You know, a marshmallow in space that isn't rotating is going to get roasted on one side, even at one au from the Sun. Oh I see, So just putting a marshmallow out in space in orbit around Earth, it's going to get toasted or melted at least. Yeah, if it gets like tidally locked to the sun, so one surface of it is always facing the sun. Then the sun will eventually toast, it will heat it up to like, you know, more than a hundred seed and then and then what will happen. It will become like goof floating in space and I know which sentence, and then an attack Earth. It will be warm and so it'll be liquid. I don't know if life can spontaneously form inside space marshmallows, So I think that's a topic for another podcast. But then you're saying that it can't actually roast like you will. You'll never get it that nice brown color because in space you can't have that. Yeah, the roasting, that browning is actually an oxid Asian effect, right, that's reacting with the air. And so that can happen because there isn't any air out there. So you can melt a marshmallow in space. But I don't think you can brown it because there's no oxygen out there. Really wouldn't at least like you know, totally convert into carbon or something. You know. I find it hard to be heat up something in space, even to a million degrees, and when in't like char at least. I think the charring in some biochemists out there should correct me, involves the process where you are, you know, using oxygen to react with the elements and doing chemical transformations. If all you're doing is heating it up, and you're just going to be heating it up, you're not gonna be making any other chemical transformations. But I guess there is a little bit of oxygen, right, because the marshmallow does have some air tract into it, as as scientists have found out. Oh that's true. So if the marshmallow freezes and cracks and expels a little bit of oxygen, so now it has its own tiny little atmosphere, and you heat it up fast enough, it could also use that oxygen to brown I suppose. Yeah, there's like an interdisciplinary study here. We need like biochemists and physicists engineers to build this giant stick. Well, we're writing a grand proposal to the National Snack Foundation and uh, maybe they'll fund this study. But they don't give you money. They just give you more snacks in kind costs. They call it all right, aiden, Well, I think that's that the answer for you there. You need to put the marshmallow to roasted in space. You need to put it about point four adu, so the way to the sun, the somewhere between Venus and Mercury. If you put a marshmallow out there, spin it around, it will eventually melt and turn goody, delicious, and maybe even a little crispy. Let us know, and don't forget to publish your work, and stay tuned for our next episode, in which we asked the same question for chocolate. But in the meantime, we'll answer more questions from listeners when we come back. We have questions about galaxy collisions and micro meteors. Will get to those, but first let's take a quick break. All right. We are answering listener questions and also getting a little hungry talking about marshmallows, sns more. We should stop recording this podcast around lunchtime, and I think it focuses our jokes around feud, or at least after lunch. You know, so they were hungry for dessert, but then we're going to be full and sleepy. But who needs to dessert when you have the knowledge and the mysteries of the cosmos to snack on? Exactly? But we're supposed to be soothing our listeners to sleep and not going to sleep ourselves on the podcast. What do you mean we're actively trying to make people sleepy? No, but I got a lot of listeners who write in and say that they enjoy listening to our voices as they fall asleep, which I think means we put them to sleep. Or did they like our voices to be the last thing to hear before they fall asleep. That's very feels very intimate. You're getting very sleepy. What's your day? I don't know. Did you turn off the lights now you're going to give the nightmares? Is the stove still on? Is there somebody right behind you staring idea you're gonna give me nightmares? Is there a physicist standing over your deck right now? Did you lock the windows? Everything is fine, nothing is screwed up. Go to sleep. The universe is going to turn on without you. Everything's out of control, I mean in control. But as you go to sleep, think about the nature of the universe and what your questions are. It's right, yeah, and a lot of people have because they send us their questions and we are answering them here today on the podcast. Is our next question comes from Ryan, who is a question about our impending collision with the Andromeda galaxy. Hey, Daniel and Jorge, I have a question that spent on my mind for a while regarding galaxies, and they're galactic collisions that can occur. So my question is, how is it the galaxies like Andromeda and Milky Way are destined to collide with each other in the far future. I know that the universe is expanding and therefore all matter isn't a constant motion, but how can two massive objects like galaxies just be going towards each other? Thanks for inserting the question by all right, Thanks Brian. It sounds like it's something that's he's been thinking about it for a long time. Yeah, maybe Ryan falls asleep wondering about the cosmic fate of the galaxy. Well, he would have to sleep a lot for it to happen in his sleep, right, Maybe he's wondering how long can I sleep? Should I set my alarm clock for a million years, for a billion years? I don't want to miss it? Or do I have to set my alarm or will joint galaxy crashing into us waking up? If you can sleep through that, then like wow, that's a superpower. I haven't managed to sleep through my morning at our kids morning routine, So maybe if a galaxy collision happened, I wouldn't know it. Well, that's another question. How many galaxies would it take to wake up Rhead or any cartoonist. But yeah, Ryan asked about our impending collision with Andromeda, and so phillis in Daniel. We're going to collide with another galaxy. We are going to collide with another galaxy, and Jomeda is headed our way, and Drameda is the nearest galaxy to us, but it's still pretty far away. It's millions of light years away. But there's something really cool that I think is not widely enough appreciated about Andromeda, and that's how big it is. It's millions of light years away, but it's actually so big that if you could see it in the night sky, it would be bigger than the full moon. It would be like a huge object in the sky. Well, I mean, if if it's right next to us, it would occupy our entire night sky, right, that's right. But even millions of light years away, it's still enormous. You know. Somebody wrote me and asked me a question about seeing distant objects using telescopes. And the thing that telescopes do is not so much magnification as gather more light so you can see dim things right there, like enhance the brightness of things more than they make them bigger. Because a lot of exciting things the nice guy are already really big. They're just too dim to see. So Andrameda is like that, it's incredible if you can see Andrameda in the nice sky. It's really very dramatic. Oh, I see, you're saying, like if we could keep our eye cones open and of and looked at the sky at night, we would see Andromeda and it would be about the size of the moon. Yeah, it would be larger than the full moon. People imagine that all the galaxies are out there are like the tiniest, dimmest little dots. They're even dimmer and further than stars. But this is like look up in the nice sky. You would see this enormous spiral galaxy like right there. It would be incredible, but it's just so dim that you can't see. It's not newly as bright as the full moon or many of the other stars in our galaxy. Maybe it's a good thing we can't see it. You know. Imagine if every time you looked up at the sky you saw this giant galaxy coming towards you. I mean, be frightening, right when it's like, oh I look at that beautiful moon and the giant galaxy. Yeah, be like is it getting there? Is it coming this way? It is getting bigger, but by a very small amount every year. And this is a question people ask kind of often. They're trying to reconcile two things they've heard. One is that Andromeda is coming towards us, and the other is space between galaxies is expanding, and the whole universe is expanding, and everything is getting further and further apart. And these two things seem to be in contradiction. So I get a lot of people writing in asking this kind of question, or this very exact question. That's right, because we have talked a lot in this podcast about how the universe is expanding due to dark energy, and the universe is getting bigger and bigger, and so I guess Ryan's question is, like, very everything is getting bigger and bigger and farther and farther away. How is it that we are even in danger of colliding with another galaxy. Yeah, and so there are two effects happening there right. One is the universe is expanding. New space is being created all the time, and that new space is not just being made out there in deep space. It's made everywhere. It's made between me and you, it's made between the atoms in your body. It's made between the Earth and the Sun, it's made between the Sun and other stars. It's everywhere. Home geniously, like everywhere in space is expanding. But that expansion is not that dramatic, you know, over a light year or so, it's like a centimeter per year, and so it's sort of like a very gentle breeze. And the other effect that's going on, of course, is gravity or other bonds. The reason that dark energy is not tearing you apart is because the bonds in your body are more powerful than dark energy. Over short distances, they win, and over distances like between the Earth and the Sun, gravity winds. So gravity, even though it's super duper weak compared to the other forces, is more powerful than dark energy over these short distances. But as distances get larger and larger, gravity gets weaker and weaker. Right, you don't feel the gravity of distant objects as much as you feel the gravity of nearby objects. So as distances get larger, gravity gets weaker, but dark energy doesn't. Dark energy gets more powerful with distance, so at some point, over long distances, dark energy winds, and over short distances, gravity winds. Like right now, dark energy is trying to pull our solar system apart, or even you apart, right, but the gravity is sort of keeping things tightly bound together. Yes, it's like there's a very gentle breeze, but you and your friend are holding each other's hands, so you're not getting pulled apart. But over large distances that that gentle breeze becomes like a hurricane almost right, Like it's additive like that, The breeze just gets more massive the longer use sample it, and gravity gets weaker. Because if we're talking about gravity between galaxies or between clusters of galaxies, now we're talking about hundreds of millions of light years. And while gravity's extent is infinite, right, you do feel the gravity of Andromeda and other galaxies, it drops off like one over the distance squared, and so you get twice as far. It's four times weaker. Over those vast distances, gravity gets pretty weak and then dark energy takes over. So if you look at the universe only at the scale of like superclusters of galaxies, right, the structure is our solar system, that our galaxy, and then clusters of galaxies, then clusters of clusters of galaxies that we call superclusters. Between superclusters, dark energy is winning. Superclusters are moving away from each other faster and faster every year. Gravity cannot hold them together because the distances are too great. Yeah, it's almost like, you know, we're on a tiny little island and the other galaxy cluster isn't another tiny little island somewhere in the over the vast ocean, and the ocean is getting bigger yea, And the largest thing that gravity can hold together is sort of one galaxy cluster. So like the Milky Way and Andromeda and the other galaxies in our cluster that we call the local group, these things are gravitationally bound. Gravity is strong enough to hold them together like a little group of islands, but the ocean between our cluster and other clusters is expanding like a supercluster. Astronomers argue about whether it's even really a thing, because they don't not sure whether it's gravitationally held together or just sort of currently right now near each other, but dark energy will eventually tear it apart. I see, that's kind of sad, but I guess you know, it sort of depends on the distances, right, Like, if our cluster was closer to another closter close enough, then they would maybe feel more gravity towards each other. It just so happens that there's a bunch of space in between. There is a bunch of space in between, and so that lets us answer Ryan's question. You know, how is it possible if space is expanding, for Andromeda the Milky Way to becoming close to each other. Well, the answer is that gravity wins over dark energy between neighboring galaxies. Even though in Drameda is millions of light years away, it's got a lot of gravity, and that gravity is pulling us towards it, and our gravity is pulling it towards us. So what you're saying that the Milky Way does feel gravity towards Andromeda, like we feel it, like it's actually changing our trajectory. Absolutely. Yeah, it's a huge object. It's much much bigger than the Milky Way. It's much more massive than the Milky Way. So we do feel it's gravity, and you know it's going to take a long time. It's billions of years for these large distant objects to pull each other together. But eventually that's what gravity does. You know, gravity operates over large distances in long times, but it's very patient. It just keeps going. It's like the energizer Bunny of the universe. But you know, I kind of interpreted Ryan's questions a little bit differently because he used words like destiny and like why is our galaxy destined to crashing to another one? And so I think his question sounded more like he was wondering, how is it a coincidence that we, in this vastness of space our galaxy isn't a crush collision course with another galaxy when you know it could have easily, you know, be aimed to to miss this or you know, it's almost like trying to hit two pebbles out there in the vastness of space. Yeah, and if you just imagine like a bunch of bouncy balls in a huge volume of space, you figure they're never going to hit each other. But these bouncy balls are attracted to each other. Gravity is pulling these things together, So it's not random that these things are pointed towards each other. It's not just bad luck or good luck, depending on which side you're rooting for. Gravity is actively pulling this stuff together. The whole reason the galaxy exists is because gravity has pulled the matter together to make the stars, and then pulled those stars together to make galaxies. And now it's pulling those galaxies together to make bigger galaxies. And this wouldn't be the first collision for the Milky Way. We've collided with many other galaxies. We have other little dwarf galaxies inside our galaxy that we've already gobbled up and eaten, and most galaxies out there, I've been through several rounds of collisions, and so more collisions definitely in our future. But I guess that you know, there is sort of an element of luck to it as well, Right Like, we're not destined, Like our whole galaxy cluster isn't destint all destined to crash into each other at some point in the future, right Like it's not all going to be just a giant black hole eventually, is it? Yeah? Actually, it kind of is definitely become a giant black hole. If you look really far into the future, these islands that gravity is controlling, eventually they will pull them all into a black hole. The only thing that lets us resist that is angular momentum. Like the reason our Milky Way hasn't yet collapsed into a black hole is because those stars have a lot of velocity, so they can maintain an orbit around the black hole. But eventually they'll lose that. They'll radiate away some of that energy and gravitational waves, or they'll bump into each other and they will collapse into the black hole. And similarly, all the galaxies and our local group eventually will coalesce into one meta galaxy with a super duper black hole at its center eventually will eat all the stuff. Wow. But then we're talking like trillions of years now, right, not like billions. We're talking like maybe even like, you know, hundreds of trillions of years. Yes, exactly. But the deep, deep future of the universe, assuming dark energy keeps going, is that it's nice and cozy, little crowded. It's a bunch of super isolated, super massive black holes, and it's going to take a really really long time. But The cool thing is that if you took like a time lapse movie of this process, it would look like it's happening really fast. It would make a lot of sense. You're like, oh, crash, crash, crash, and then the whole thing coalesces. We're just sort of watching it in super duper slow motion. Interesting. So it's a little bit of a coincidence we're crashing into Andromeda in the next couple of billion years, but it's not a coincidence in the long term of things, where you know, eventually everything's going to collide with with itself exactly. It wasn't predestined that we would collide with this galaxy at this particular time, but there was no way we were going to avoid colliding with other galaxies at some point. So either way, it's still a few trillion or billion a year US and so Ryan used to have a lot of time to sleep in. It's right in Rusty marshmallows the rest easy. All right, let's get to our last question of the day here, and it's about micro meteors and surviving being out in space. But first let's take another quick break. All right, we are answering the listener questions here today on the podcast, and we've had two awesome questions and our last one is about micro meteors and it comes from Bess Hi Daniel Jorge. My name is boss Um from in the Netherlands. I have a question for you guys. So if you travel really quickly to space, like you go really fast, maybe almost just feel a light, what would happen if you would hit like a tiny piece of debris or maybe like a tiny rock. Would it bounce off or would it explode the ship? And if so, like, how are we able to to travel in the future without having to worry about exploding with flight? I was really curious about that. Thank you, bye bye. Alright, awesome question here about being out in space, I guess is space is not a complete empty vacuum, right, There's stuff floating out there in space. There is a lot of stuff out there in space, and not just like the tiny quantum fields that are fluctuating at very low energies. There's really stuff out there. You know, the Sun pumps out the solar wind which is filled with particles, but also there's lots of space dust and micromedeors and all sorts of things. Whizzing around out there in space. Yeah, he talked about micro meteors, and so what is the micromedia. Micromedia is just like a pebble that's out there in space, you know, micromeding really really small. And the stuff that's out there in space has been coalescing in the Solar System for a long time, and so most of it's in the form of the Sun and the planets and even big asteroids. But sometimes those things collide and leave debris. And we talked on an episode recently about space dust, which are like little particles of stuff that are out there in the Solar System. Nobody's exactly sure where they come from. Maybe they're whipped off of storms on Mars. Maybe they come from collisions of asteroids and the asteroid belt. We're not exactly sure. Exploded marshmallows, perhaps from failed experiments by aliens, alien campers. That's right, edible space junk, just open your mouth and space. And there is also a lot of debris. You know, there's a lot of debris near Earth from you know, satellites that have fallen apart and burned up, and you know, screws dropped by astronauts and stuff like that, and some of the stuff is moving pretty fast yea. And in fact, the Earth sort of gets pelted by micromedeors all the time, right, Like we're literally getting showered by these tiny little rocks, except that they get burned up in the atmosphere. Yeah, the size of the rock is inversely proportionals the frequency of the chances that it hits Earth. So really really big rocks like the one that killed the dinosaurs really rare, small enough rocks to make shooting stars, not that rare, like you can see them on a random night. Really really tiny rocks that don't even make shooting stars happen all the time, like constantly, and so like if you see it as a shooting star, it means the atmosphere burned it up. But if you are above the atmosphere, those things can hit you, right, absolutely, those things can hit you. And they're moving pretty fast. You know. The Earth is moving around the Sun at like thirty kilometers per second, so these speeds are really high, and things are flying through the Solar system, you know, like five to twenty kilometers per second is totally not unusual for micromediors. These tiny little space petals, whoa You just made me realize that maybe it's not the meter hitting you, it's like you hitting the meteor, like it was just floating out in space peacefully, and then the Earth just kind of you and the Earth so came barreling around and and you hit the little rock. Yeah. The rocks have their own little podcasts like, Hey, I'm worried about people coming and hitting me at high speed. Yeah, I had to dream or a giant marshmallow totally engulfed or ecosystem. It was delicious and it had a lot of air in it, but now everything's really sticky, I don't know, embedded in giant marshmallow. Pretty good way to what if our entire milky way like an andramatous sized marshmallow, right, that would be interesting. It depends is it melted marshmallow or is it nice and room temperature. Because I don't want to be boiled alive, and so I have a molten marshmallow. That's times horrible. That's true. That probably also ruined the marshmallow. Nobody wants to eat marshmallows with boiled cartoonists inside. That's right, nobody wants more of those. But Boss's question is also about like how do we survive this field of micro meteors. Like, if we're moving through space at high speed, you know, then these things basically coming at us at high speed, how can we possibly survive transit between stars? Right? It's it's kind of like being shot at by bullets, right, Like these things are going faster than a bullet. Yeah, these things are super fast, and like bullets, they can be small, but they can carry a lot of energy. Right, bullet rips right through you because it's going super duper fast, so it's a lot of kinetic energy. So yeah, these things are dangerous and everybody that goes out into space, even near Earth, needs shielding to protect themselves from these things. Remember we talked about the Juno spacecraft that went out to explore the outer reaches of the Solar System and it was pelted by space dust so much so that it's solar panels had all these little spellations that came off that helped them even measure the amount of space dust. So yeah, it's like being in a dust storm right where it can shred you kind of right, because these things are going like like kilometers per second, like three to eighteen kilometers per second. Exactly. Imagine being in a dust storm where the winds are kilometers per second velocity that it's like sandpaper, right, it would totally shred you. And so I guess the solution if you're at third space is to have shielding. I guess, like something to block those incoming bullets. Yeah, and so we got a lot of stuff out there in space, and so NASA has worked on this kind of thing, and for example, the I s S the space station has shielding. And the standard solution to this is something called a Whipple shield, named after an engineer whose last name is Whipple. And the basic idea is to have like multiple layers of shielding. So you have like your internal shield, and then you have a gap and you have another layer of shielding and the outer layer shielding. Its job is to break up the micro meteorite into even smaller pieces, so instead of having like a bullet instead you have like a bunch of smaller bullets. And the idea is that it spreads out, so it's not like one localized impact on your inner shield, like spreads it out over multiple smaller impact sites. Interesting, but what is this outer shield made out of? Doesn't it get destroyed when a bullet hits it, so eventually you can get used up. It cannot last forever. You don't want to get hit twice in the same spot. Though. Some people are working on these shields that are self healing that will repair a hole in themselves. Interesting. How does that work? Well, they use some sort of gel so that at low temperatures it's solid and it can act as a shield. But then when something passes through it, the friction of it heats it up and so it becomes liquid and then it like flows just close up the whole automatically. Oh whoa interesting Now, of course you make me think of what if we make it out of marshmallows, like it bounce to get absorbed and with the heat also you know, reseal it. I think we're gonna have to consult the marshmallow lab, but you see Santa Barber to find out. I'm thinking like a layer of marshmallows to slow down the meteor, than a layer of chocolate to really take out the kinetic energy. And then Graham Cracker plates to um to really fortified. And when we walk into the lab and see somebody heating this thing with a laser, and you're like, no, seriously, we're doing space physics. Here. You see somebody with like a gun pointed at a Smores sandwich. There doing real science. Yeah, and so this is sort of the state of the art. It's a whipple shield. You have like a thin outer bumper and then you have a gap, and you can have multiple layers of it, right to try to like make yourself protected from even higher energy objects, so you can break them up in several stages. You can do things like stuff the gap with materials that could help absorb the energy, like kevlar, etcetera, like a bulletproof vest literally, yeah, like a bulletproof But in the end you have to build shielding because, as Vast says, if this thing passes through your ship and punctures it, then boom your toast, right. So this could be a real problem, and it is going to be a real problem if we ever do get to travel in between the stars. Yeah. I've always wondered, like, if you're going through space and you're going really really fast, almost at the speed of light, like if a tiny rock hits you, it's your toast, right, Like it would have so much energy exactly unless you have a really good shielding at the front of your ship that can break it up so that it becomes like many smaller rocks. And the key here is the pressure applied for each rock, Right, it's amount of kinetic energy delivered, like per area. Same kinetic energy that's in a bullet isn't a big deal if it hits over a much broader area. Like that's how a bulletproof vest works, right. It takes a bullet which is trying to put a lot of energy into like one half a square centimeter, and it just spreads it out over your entire chest. And so that's why when you're hit with a bullet and you're wearing a bulletproof vest, you get knocked over, right, but you don't get penetrated, doesn't like go into your body. So that's the idea is to spread out the energy over a larger area. But yeah, if it gets through, then you've been shot with a bullet and you're dead. I guess the International Space Station that's covered in all this shilling, they have all sorts of shielding on the space station. They have like a hundred different kinds of shields based on like how much time the astronauts spend there because you have to balance mass, right, these things are heavy, and so lifting them into space costs energy and money, so you don't want a bunch of shielding where you don't need it. So they have like more shielding with the astronauts spend more time, and then they have like one special room that's like super shielded, so if they see like a shower of these things coming, the astronauts can like you know, basically go into their panic room. And recently, one of these things like smacked into the one of the windows. They have this like observation room in the I S S. We have big windows you can look on the Earth, and the micromedia right hit one of those windows and you know, took out a little vivid and so that was a little bit scary because if it cracks the window, it's kind of a panic time. But there, yeah, exactly then it time to do space marshmallow experiments. Yeah, quickly before you can run out of auxin. And and like you said, these things were out right, like they're constantly getting pelted by micrometers and so they were out right. So is is a space station doesn't have like a maintenance program where it replaces its shields every now and then. Yeah, exactly, you got to replace them and launch new ones. And that's why everything in space is constantly getting degraded. And so when you hear people talking about, like, you know, launching space based solar power or space based or space space that, remember that these things will not last that long in space. This huge radiation to fry the electronics. But there's also basically space sandpaper wearing down everything. Is this you know, constant wind of stuff just like trying to destroy in space. Remember the atmosphere protects us from all of this. You know, it's basically a huge shield. It sounds like you want to have maybe some air trapped around your space station to protect you. Maybe maybe trapped in the form of marshmallows. Yeah, or maybe we should use the plan we talked about once. Instead of lying somewhere else away from our solar system, we should just move the entire solar system, like we want to go visit another star. We just turn our son into our rocket. Remember that idea. Yeah, Yeah, we had a whole podcast about it. Yeah, And that would solve a lot of these problems, right, because you could bring your atmosphere shield with you as you move around the galaxy. And you also need shielding if you're going out in space by yourself, right in a space suit. Yeah, that's one of the dangers of these e v A s when the astronauts leave the space station and they're just protected by their suit. They have some shielding on these suits as well, but you know, that's a pretty dangerous if you're hit by a micro meteorite, it could puncture your suit. And so they do have them shielded, and they do some calculations. You know, they say, we want less than a one percent chance that we're gonna lose an astronaut per decade, and that's the threshold they apply to figure out like how much shielding they need. Yeah, I guess it's like walking out into the middle of a gunfight, kind of hoping you don't get hit. Yeah, you're doing signs in the middle of a gun range. That's gutsy, Daniel. How dangerous is your day job. I'm not taking any risks like that. I'm just eating too many marshmallows for science. And so you're building a little you know, shielding around your middle section, not so a little anymore. All right, Well, that answers a question for Boss. I guess micrometers would shread you? Is the answer to his question. You know, if you're out there without any shielding, eventually probably something is gonna start poking holes, So start training your your outer suit. That's right. So before you make plans to move out of the Milky Way to avoid the collision with Andromeda, pack a lot of marshmallows, and also pack a lot of shields and sorry, in a suit of armor if you can, guess be iron man if you can, or carbon fiber man. Maybe all right, Well, that answers all of our questions. Thank you to all of our listeners for sending in. There are questions. We really enjoy answering them here online. Please don't be shy, right to us two questions at Daniel and Jorge dot com. And keep being curious and keep tasting those marshmallows just right. If not while you're awake, then while you're asleep, which hopefully most of you are by now. If we did our job, maybe we should be talking quieter and quieter as the podcast gets on. Yes, what you start whispering good night, pleasant dreams? Al right, everybody, thanks for joining us. See you next time. Thanks for listening, and remember that Daniel and Jorge explained the universe is a production of I heart Radio. For more podcast from my heart Radio, visit the i heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows. Ye