Daniel and Kelly’s Extraordinary Universe - Can supernovas cause ice ages?

Episode Date: June 18, 2024

Daniel and Jorge talk about how the greatest cosmic fireballs might trigger ice ages here on Earth.See omnystudio.com/listener for privacy information.

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Monica Patton. Elaine Welteroff. Learn how to get comfortable pivoting because your life is going to be full of them. Listen to these women and more on She Pivots. Now on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hey, Jorge, been enjoying the recent run of rainy days? Yeah, I like a rainy day. It's kind of cozy.

Well, I guess that's what we get for living in an ice age, rainy days even in Southern California. Where we're in an ice age? I don't see any woolly mammoths around. Yeah, the woolly mammoths disappeared and not just because the temperature. What happened? They moved to a warmer planet? No, I think our ancestors. turn them all into soup and blankets so they could be cozy on rainy days.

Wait, that's not what I saw in the movie, Ice Age. Not a documentary. It's also not PG, I guess. Hi, I'm Jorge Maker Tuna and the author of Oliver's Great Big Universe. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine and I live for the sunshine. Well, we all live because of the sunshine too, right? Yeah, that's right. Almost all energy used by life on Earth comes initially from the sun. It grows vegetables and food and that's how we can all stay alive and warm also.

That's right. When you burn a piece of wood and you feel that glow, it's like it's released that original solar energy. Trees are basically solar energy batteries. Yeah, whenever I see a big green field, I always think, wow, that's an awesome natural solar panel. I know it is incredible that evolution has devised this way to eat photons and turn it right into chemical energy. Pretty amazing. Yeah, yeah.

Although in between, there's, you know, a nice salad. And maybe more in between is a nice piece of fried chicken. I like to think of all the photons in my salad. Although it is a little heavy. It's not very... light to have a fried chicken salad. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of IHeart Radio.

In which we try to shine a light on all of the heavy questions of the universe. How does it all work? What are the smallest little bits? How do those come together to make grass and chicken and people and planets and stars and black holes and everything else that we see out there in the universe? It's an incredible dizzying array of complexity. we think it's possible to simplify, to boil it all down into a few basic ideas that could be understood by you.

That's right. We try to serve up a nice tantalizing buffet of amazing facts about the universe, amazing discoveries, and also incredible mysteries that we are still trying to figure out in a way that is hopefully not a word salad in your head. A crucial goal of doing physics is understanding the nature of the universe so that we can get a better sense for our context. Every time we learn something about where we are in the cosmos and how it works, it changes the way we relate to it,

how we live our lives, what we think about it. And of course, at the center of our local cosmic neighborhood is the sun, which is the source of all energy for life on Earth and could eventually fry everything on Earth. Yeah, because I guess it's easy sometimes to forget that we are just sitting atop a little tiny rock flying around a big burning ball of gas in the middle of a gigantic space full of things

that might at any moment kill us. It seems like sort of a precarious and fragile situation. Like, if we didn't live it and you read about it in a science fiction novel, you'd be like, that sounds kind of implausible. You mean the idea that we were just like perched in the middle of a giant void that might kill us at any time? Yeah, that we're the perfect place between a huge freezing void and an enormous ball of fire that could kill us.

And we're in the Goldilocks zone right in between them. Yeah, and an orbit that is sort of mirror. miraculously stable, right? That just keeps going around the sun over and over again in a very stable way. It is sort of amazing that it's worked for this long, and we are grateful for it. It's amazing that the sun arises every day. Because it could not, right? It could just stay in bed like your local cartoonists, yeah.

Yeah, that's right. Thankfully. But the sun and other stars out there are not eternal fixtures, which will be pumping out energy to support life on Earth and alien planets forever. Sometimes they go boom. Sometimes they explode an enormous supernova which can fry their local region of space. Yeah, I think we're used to the stars

being out their way out there and not really affecting our everyday lives other than making for nice night sky view here on Earth. But it is possible for those stars out there to actually affect us and maybe change the way that we live. That's right. It's not so crazy to imagine that our sun's variations

as it gets brighter or colder as we move closer or further away could affect temperature on Earth and even potentially cause ice ages or global heating. But what about other stars out there in the universe? How susceptible are we to their quirks? Or their big explosive quarks, for that matter. So to the on podcast, we'll be asking the question. Can supernovas cause ice ages?

Well, I feel like that's two movie names and one title here. Supernovas and Ice Age. I know. I know it means we're in danger of jumping the shark because now we're doing like bizarre mashups, you know, like shark tornado. I think we jumped the shark a few hundred episodes ago, didn't we? And we're still here.

We're still riding the shark. I promise I didn't come up with this episode by randomly throwing darts at the wall with topic names. Maybe we should do an episode on the physics of sharks. Jumping. The physics of shark natos. You know, there's a lot of questions there. Like, how do you launch the shark?

What are the aerodynamics of the shark? In air. Yeah, we got a crossover episode with Katie. She probably knows all about it. There you go. And then you could have maybe Henry Winkler, the Fonds, as a guest star, just to wrap it all up. And then we'll take a field trip and literally jump over a shark. Just to hammer that point home if people weren't getting it already.

Right. I think that might be. Eagle and ill-advised, but hey, if you want to go for it, I'll be unsure taking picture. But this is not just a random collection of words mashed together for a new idea for an episode. This is actually something on the cutting edge of science. Yeah, the idea that maybe a supernova out there in space could have maybe or can cause an ice age here on Earth. And so as usual, we were wondering how many people out there had thought about this question or maybe even link those two ideas together.

I guess if it was close enough, it could do a lot of damage one way or the other. Supernova sent out heavy atoms, and on a planet, if they pile up around the planet, they can block the other sunlight that's closer to the body, and it can cause ice ages indeed. Hopefully that doesn't mean the sun, because I'm not sure if the sun were to go supernova. It would be cold enough for an ice age, but if it were like a close star, maybe some of the matter coming off of that star would shield us from the sun and the temperatures would cool. I don't know. Seems far-fetched, but I can't think of it any other way.

This is a reel if a butterfly flaps its wings on the other side of the world kind of question. Sure, a supernova would admit charged particles that would mess with a magnetic field and potentially strip an ozone layer. So that would affect the climate dramatically. So, yes, supernovas could cause ice ages. Thanks very much to everybody who participates. I love hearing your voices on the topics of the day. If you'd like to lend your thoughts to this segment of the podcast, please don't be shy. Write to me to questions at danielanhorpe.com.

I'm pretty sure nobody ever regretted it. Would they tell you, though? You know, people on the internet are not shy to share their opinions. So I'm pretty sure I would get a grumpy email if somebody was really grumpy about it. Well, I think if they regretted it, they wouldn't reply back again. So think about all the emails you're not getting. If you participate in this segment of the podcast and you deeply, deeply regret it, please write to me, share your pain.

Just having to fill out a survey after every interaction, Daniel. If you enjoyed talking with me, please take a moment to fill out the survey. No, then they're going to regret it because everybody regrets getting those surveys. Well, maybe you haven't filled out a survey about being asked to fill out a survey. And then they recursively begin to hate me. Yeah, there you go. And as time goes to infinity... The universe will fill with surveys.

It'll approach to having gained zero knowledge. And 99% of the bandwidth, the internet, will be surveys. But anyway, these are great answers from people. It seems like people think that maybe there could be a connection there. In the same way that maybe a butterfly can flap its wing and I could get fried chicken the next morning because of that. Yeah, it's sort of a cosmic butterfly. affect. Imagine a butterfly on an alien planet triggering a supernova in that solar system,

which then somehow makes ice ages and hours. Amazing power of butterflies. Yeah, and fried chicken as well. But this is an interesting question. Could a supernova out there in space somehow affect the climate here on Earth to the extent that maybe we actually get an ice age? Amazing. So maybe let's start with the basics here, Daniel. What is a supernova and could one happen near us. A supernova is a really exciting and dramatic possible end point to a star. Not every star ends the same way. The fate of a star depends almost entirely on its initial mass. These stars are formed from huge clouds of gas and dust where something has triggered a gravitational runaway effect. So a clump of stuff pulls together. And if it's too small, it makes something like

a brown dwarf. But if you get enough stuff in there, you can ignite fusion and you can get a star and it can be burning. A lot of stars are kind of small. They're called like red dwarf stars. And those stars are just going to burn for a long, long time and then eventually become like white dwarfs. Larger stars, though, when they run out of fuel, that fuels what's preventing them

from collapsing further gravitationally by providing pressure from the fusion inside of them. Larger stars, when that fuel runs out, they have so much gravity that they collapse, which then triggers an explosion at the heart of the star, which we call a supernova. but I guess a couple questions there first of all

do smaller stars ever run out of fuel don't they run out of fuel too and what happens to them when they run out of fuel? Yeah smaller stars definitely run out of fuel because they're smaller their core is not as high temperature or as high pressure

so they go through their fuel more slowly so they can last for like billions and billions of years but they eventually will run out of fuel and they'll just form white dwarfs white dwarfs are just like their remnant of fusion but it's no longer fusing like if you produce a bunch of carbon but you're not hot enough to fuse carbon

then you just turn into a hot lump of carbon and that white dwarf sits around for maybe trillions of years glowing in space without fusing until cools enough to become a black dwarf but somehow there's a difference between that and a larger star because the larger stars collapse the smaller stars don't collapse

yeah the larger stars have more gravity and so they can overcome the structural strength of the fusion remnants like the reason that white dwarf doesn't collapse further is that the structure of that big blob of carbon or nickel or whatever it's turned out to be is stronger than the gravitational forces but if you have enough mass you can overcome that and you can trigger another collapse and that creates intense pressure and temperature at the core so now you can fuse stuff you couldn't fuse before and that creates very very fast burning very short-lived reaction which causes an explosion again which blows out a huge amount of material

And that's the supernova. Well, the other question I had was, does the fate of a star also depend on what it's made out of, not just its mass? Like, does a star that's pure hydrogen have a different fate than one that's more mixed in with other elements? Yeah, absolutely. The amount of metal that a star starts with

can really change the star's behavior. The more metal there is in a star, the more opaque it is to its own radiation. So the more it like absorbs those photons rather than emitting it. So that can really change the temperature in the star, which changes the rate of fusion. And so the question of like how much metal each star starts with is really important one. And one we're still trying to understand with a whole episode recently about how metal is our sun. And we know that it's like a couple percent metal by which we mean things heavier than helium and hydrogen.

But it is an important contribution. And so it's mostly determined by the mass of the star, but also other things like the composition. and it's not totally understood. Like, which star will go supernova is not something we can actually predict. Now, does a star having more metal make it more explosive or less explosive? Like, is being more metal, more radical?

More metallic stars are more likely to undergo supernova and turn into neutron stars, whereas low metallicity stars are more likely to collapse directly into a black hole and might not even give you a supernova. Interesting.

Yeah, I guess if it goes straight into a black hole, then there's nothing to explode out because nothing can get out. Yeah, exactly. But that's from like really massive stars above like 40 times the mass of our star. In the intermediate region, like between 10 and 40 times the mass of our star, a lot of these will go supernova. But again, it's hard to predict. It's a very chaotic event in the moment at which a star is going to go supernova is not easy

to tell. Like people have been watching Beetlejuice recently because it's brightness is. become quite variable and they're wondering like is it about to go supernova but nobody can tell when a star is about to go supernova we don't understand the process even in simulation it's not something we know how to explain yeah that's something as you said that also made me curious was uh this idea we don't really understand this process very well and i guess it's interesting that we haven't really studied supernovas very much right like we haven't been present when we see one we haven't been up close to another star when a supernova goes up, thankfully maybe.

But it's all sort of done through simulations and models of what we think is happening inside of a star from what we can gather from looking at these pinpointing in the sky, right? Yeah, we certainly have studied supernova, and you're right, a lot of the work is done in models. The reason we haven't studied more supernova is because supernova are really rare. It's not something that happens all the time, sort of thankfully. otherwise we might have been fried out of existence. You know, in the Milky Way, for example, we expect there to be like two supernovas

out of the hundreds of billions of stars every hundred years. And so it's not something that happens very often. And weirdly, we haven't seen a supernova in the Milky Way for a few hundred years. So that's another mystery we did a whole podcast episode about. But it's not something that happens often enough for us to get a lot of data.

It's like spontaneous human combustion. You hear about it happening occasionally. It's really hard to bring. predict. And so you have the sort of sparse data to work with to understand, you know, what might cause it? But I guess what makes it hard to predict? Like, aren't there signs that the sun goes through or the star goes through right before it blows up? Like doesn't it maybe ramp up in brightness or something? We'd love to know that. And it's really tricky because we can't monitor every single star until one of them goes supernova. There are just so many stars. So typically

what happens is we see a star go supernova. Then we start taking a lot of detailed data on. it, but that's all post-supernova. And we'd be very lucky to have been watching in great detail a star just before it goes supernova. And that's one reason why we can't tell with stars go supernova. And from the theoretical side, it's very tricky because it's very intense physics.

The stuff is moving close to the speed of light. It's very high density. It's very high intensity. There's a huge number of particles. This kind of calculations are very difficult to do correctly because not only are all the particles important, but it's very chaotic, like a small change in the structure of the star

can lead to a large change in how that collapse happens and the shock waves. It's very complicated. I'm actually working with some folks at Berkeley who are doing supernova simulations and each one of them

requires running the supercomputer for millions and millions of hours. So we don't even have a lot of examples of supernova in simulation. Wow, yeah. And I guess if you, you know, try to look for a supernova and by looking at the sky all the time,

you'd still be waiting, right? Like you said, we haven't had one in a long time. When was the last supernova that we've seen? In our galaxy, the last supernova was seen, I think, by Kepler. So 400 years ago. 400 years ago. Is it possible that one happened, but we didn't see it?

Those are just supernovas in the Milky Way. And it's possible there have been supernovas in the Milky Way. We haven't seen because we can see through all the cosmic dust at the center of the galaxy. And weirdly, a lot of the supernovas we have seen in the Milky Way are far away from where most of the stars are. That's a whole funny, amazing mystery. But because supernova are so bright, we can also see them from other galaxies. In fact, when a supernova goes, sometimes they're like a million, a billion, or even a trillion times brighter than the sun. They can outshine the rest of the galaxy.

Yeah, they're super bright. But I guess at any given time, isn't it true that we can only look at half of the sky? Like the daylight side, we can't really see any stars, right? Yeah, that's right. We can only see half of the sky. And if you see a star in another galaxy goes supernova, you can tell something that's gone supernova, but we can't often pinpoint individual stars in other galaxies. So you can't be like, oh, it was that one over there, and then go check your archival data to see what you know about it.

So if we had more telescopes constantly studying the sky, then we could learn a lot more about supernova because we could see them before they go, which would be really valuable. But as we just said, basically you'd be waiting for 400 years at this point, which nobody wants. wait that long to get a Ph.D. Yeah, exactly. And we have seen, again, supernova more recently, like there was a famous one in 1987, very bright. You could almost even see it in the daytime

from another galaxy, of course, not in the Milky Way. So they're sort of rare, but they do happen. And, of course, the universe and our galaxies are billions of years old, so many of them, probably a lot of them have happened since. And so the idea is that maybe these supernovas could somehow affect what life is like here on Earth. That's the question. Yes, exactly. And so let's get into that question of whether a supernova can actually trigger an ice age here on this planet.

So let's dig into that. But first, let's take a quick break. Your entire identity has been fabricated. Your beloved brother goes missing without a trace. You discover the depths of your mother's illness, the way it has echoed and reverberated throughout your life, impacting your very legacy. Hi, I'm Danny Shapiro, and these are just a few of the profound and powerful stories I'll be mining on our 12th season of Family Secrets. With over 37 million downloads, we continue to be moved and inspired by our guests and their courageously told stories.

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to finally solve the unsolvable. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. All right, we're talking about supernovas and Ice Ages, both great movies. Different audience, though. What is the movie Supernova? I haven't seen that one. I think there must be a movie called Supernova. Yeah, of course, you're right.

There's a movie Supernova 2020. Sam and Tusker are traveling across England in their old RV to visit friends. I'm not sure it's really about a supernova but yeah That doesn't sound like it's about Astrophysics or space for that matter Isn't there an older movie called Supernova? Okay, here's one from 2000

This is a science fiction action film Is it the one starred in Killian Murphy? No, it chronicles a search and rescue patrol Of a medical ship in deep space All right, well Obviously it was not very popular But everybody should go check it out I mean, this one from 2000 has an 11% rating on Rotten Tomatoes, so...

Youch, I guess the movie didn't blow up. Yeah, I don't think it ignited passion in the audience. Yeah, it just kind of collapsed under its own weight, perhaps. But anyways, we're talking about whether a supernova that happens out there in space could somehow trigger an ice age here on Earth, which is just kind of mind-blowing to think about that something so far away that is explosive and hot can somehow make us cooler. Yeah. Yeah, it is amazing how interconnected everything is and how delicate everything

is. Now, we've talked about supernovas. Now, let's talk about ice ages. And so what do we know about ice ages here on Earth? So ice age is a generic term for basically a period when Earth is cold. There's more glaciers. There's more polar ice. And if you look back of the history of life on Earth, you see these big variations in the climate. So there are times when like all of North America was under ice sheets and then times when there's almost no ice on earth. So it oscillates between like a greenhouse earth and a snowball earth. So they're just periods in time where things were cold. Yeah, exactly. And this is just what geologists have called these historic periods when the average temperature was much lower. But it's really fascinating because it tells us a lot

about how climate on earth works. And there's not just these big ice ages which last like millions of years, but there's also cycles within those ice age. So within an ice age, there are glacial periods, which is when it's colder and interglacial periods when it's hotter. So like currently we are in an ice age, but we're in an interglacial period of that ice age. So like on average, it's colder than Earth has been in the past, but we're in a warmer period of that ice age. Whoa.

Yeah. I guess first of all, it's kind of mind-blowing to think that, you know, the Earth goes through these changes in these periods. It's like the Earth hasn't always been the same. It's sort of like a dynamic system. Yeah, it's definitely a dynamic system. And these ice ages date back like billions of years. One of the earliest ice ages we know about started like almost two and a half billion years ago.

And then the more recent ones are all in the last like 500 million years. But the earth is definitely dynamic. And you know, life on Earth has responded to it and influenced it. You know, early life, for example, couldn't tolerate the presence of oxygen. And then when oxygen started to be produced by photosynthesis, life then evolved to take advantage of that. And so it's fascinating how it's all interconnected. I guess the question is, how do we know about ice ages from billions of years ago?

Like, wasn't the Earth totally different? Do we still have evidence of those things? We knew a lot about the history of the Earth from sort of three different categories of evidence. There's like geological evidence, there's chemical evidence, and then there's evidence from life, like paleontology. And so the geological evidence is like, let's look at the shape of the surface of the earth. You know, about 150 years ago or in the mid-1800s, people were noticing weird things they couldn't explain, like weirdly shaped valleys and like boulders and the Alps that looked like they came from much further north in Europe.

And like, how did they get there? There was then that people postulated this idea that like glaciers move across the earth and like create valleys and scrape out regions of the earth and can like carry boulders with. them for thousands of miles. So the geology of the Earth tells us a lot about the sort of history of glaciation. Even though, I guess, rocks are constantly changing and moving and turning with the core of the Earth? Yeah, absolutely. There's a lot of things going on, but this is one of the processes and an important one

for understanding sort of the shape of the surface of the Earth. So that's looking at rocks. How else can we know? So we can also take samples of the Earth because the different conditions on the surface are stored in the history on Earth. So, for example, if you go to the poles and you take ice cores, they do these amazing drills where they, like, drill into the ice one or two miles deep. And then they pull it out.

You can see layers from all the different winters on Earth. And in those layers, you can measure, like, first of all, the thickness of the layer, like what was the average snowfall. And there are trapped air bubbles in there, which give you samples of the atmosphere from hundreds of thousands of years ago. and if you look at those samples of atmosphere you can do clever tricks to figure out like how cold it was back then

yeah and what it smelled like right basically you can smell the air from millions of years ago yeah that's right we might have some mammoth farts saved in the North Pole well take indeed we're all we're all smelling mammoth farts right now because it's the same air molecules that we're around back then

yeah I guess that's true and so the ice cores give us samples of the atmosphere up to like hundreds of thousands of years ago. And we can go even deeper into the path by looking at ocean sediment, like stuff that falls into the ocean and then settles to the bottom of the ocean. If you take cores of the ocean floor,

you can again drill down really, really far. You find this sedimentation. And there's a lot of details about the chemistry of that sedimentation and what's deposited in the thickness of those layers that give you important clues about what was going on in the Earth's atmosphere. And that can take you back millions and millions

of years. Well, you can tell how cold and hot it was? Yeah, most of these clues that the temperature from the ice cores and the ocean sediment come from isotope ratios because different isotopes of water, for example, have different chemistry. And so like more of it will evaporate, for example, when it's hotter. And so the ratio of these isotopes, you can back that out and figure out something about the temperature of the air, which is pretty amazing. Yeah, wow. It's sort of like carbon dating, but water dating kind of. Exactly. And it's not trivial, right? There's lots of reasons why stuff in the ocean floor or in the ice cores can get confused. But it's an important part of this evidence. There's a really impressive scientific body of work here figuring out how to deduce this from these weird clues. Yeah, it's pretty amazing. And so we can also look at fossils, right? Yeah, we can look to see where animals were and we can look to see like from fossils where they lived and what the pattern of the climate might have been. You know, if you know that one kind of creature needs warmth and you see it in warm.

areas. You can also see where else you find fossils, and that can give you a clue as to what the temperature, but the climate might have been like when they were around. So can you tell if they were sweating or if they were shivering? You can tell if their kids liked their dinners or didn't like their dinners by the amount of complaining and whining. That also changes the isotopes in the atmosphere. No, I'm totally making that up. But you know, you can tell whether organisms survive unchanged for millions of years would tell you that the climate was like. stable for millions of years. So you can back out a lot of interesting information from these fossils. And for me, this is an example of the most impressive thing that science can do,

which is like reconstruct a detailed story from all these incomplete threads, from little clues left here and there. We can really figure out what life was like on earth or understand what's inside the earth or inside the sun from all this incomplete knowledge. It's like the whole universe is a huge mystery novel. And we have just a few traces of clues. But Sometimes those clues come together and tell you a coherent story so you can become convinced that you actually know something, which you might have thought would be impossible to figure out. Yeah, it's amazing.

We can look back in time, basically. It's like having a time machine. Yeah, exactly. And so what we've seen is that the temperature, the climate on Earth has been changing a lot. And it goes through waves. And within those waves, there are mini waves. I guess a big question now is what causes all of these changes, right?

Because the orbit around the sun hasn't changed that much for billions of years, hasn't? Yeah, well, there's a lot of factors at play, but one of them is the Earth's orbit. And this is a very complex system and very chaotic. It's just a lot of feedback loops. And we're going to do some simplifications here. We're not going to be able to really treat it with its full justice.

But we do know some things about what can cause an ice age. You know, number one is the atmosphere. If life on Earth produces a lot of CO2 or a lot of methane, that can change the temperature on Earth for sure, right? And there's been times in Earth's history when life is producing more or less methane or more or less CO2. And so what's in the atmosphere can change, like how much light is absorbed by the Earth, how much is reflected back out into space. And because it's a sensitive system, that can have an impact and even cause or end ice ages. But another big factor is the orbit of the Earth.

There are these Melankovic cycles. So the Earth orbits the Sun and it's, you know, mostly stable, but there are wobbles here. Things process. And so there are periods when we're closer. and further on average. And so these things really do change a little bit. And people think that this is a big effect of these glacial versus interglacial periods within an ice age.

Wow. What causes these wobbles in our orbit? Is it other planets or something else? Yeah, essentially it's because it's not such a simple system. It's not a single mass orbiting another single mass. There's an exotricity. We have an axial tilt. We have a procession.

And all of these things are interacting with the other gravitational objects. in the solar system. And so we get like little tugs from Jupiter and little tugs from other stuff in the solar system. And these things change. So it changes like how much axial tilt we have and exactly the procession of our ellipse around the sun. And as a result, we get slightly further

or slightly closer to the sun. And that changes how much energy we get. And these little effects can really cause a change in the climate on Earth. Cool. Well, or hot, I guess. What else it can cause an ice age? Well, the sun itself is variable, right?

the sun has an 11-year cycle when it gets brighter and looser, and then the north and south magnetic poles of the sun flips. This is not something we understand very well. We don't really have a great model for the inner workings of the sun. We know there are these weird plasma tubes, but it's, again, very chaotic, and we can't see inside the sun. But the sun itself grows in brightness and then fades. So that is part of the calculation.

Like the sun is pulsating every 11 years. Yeah, exactly. And the sun is gradually getting brighter overall. all, right? The sun's brightness is increasing very gradually as it gets older. That doesn't change a lot over the last few centuries, but over the long term, you know, all these things do contribute to changes in the Earth's situation and therefore it's climate. And then you have things like volcanoes on Earth. If a volcano spews an enormous amount of stuff, you can create a cloud which shrouds the Earth and cools it significantly. Or if you have like a meteor that comes

and impacts and throws up ejecta into the atmosphere or huge amounts of water vapor can also cause a lot of reflectivity. I feel really exposed right now. Like any of these things at any moment could throw us into deathly freezing temperatures or super duper unbearably hot temperatures. Yeah. And it's this incredible combination of slow changing effects and fast sudden effects like volcanoes and meteors.

The last major component is tectonic. motion like as the plates move and as the continents themselves get dragged around the earth it changes how like water flows around the earth and how wind currents move and that can change the temperature all over the earth like are you getting more air from the arctic is it getting fully distributed or is it more segmented can really change what it's like to be at lower latitudes well also something interesting you said was that we're currently in an ice age meaning that over the long history of the Earth, the average Earth temperature is actually hotter than it is right now.

I don't know the exact number about the average, but there definitely have been hotter periods on Earth than we have right now. So when you say it's colder, you mean it's just like colder than the hottest it can get? Yeah, the Earth is now colder than the hottest has ever been for sure. There are some very, very hot periods in the history of the Earth. Of course, we know that the Earth's climate has changed. changed a lot in the last hundredish years or so because of the industrial revolution and human contribution to the atmosphere.

And so things are changing pretty rapidly. But in the bigger strokes, we are still in an ice age, though in an interglacial period. Right, right. Well, I think maybe an important dimension of this idea is the rate at which things are changing, right? Like maybe in the past, things have changed, but maybe gradually with enough time for life to evolve and to adapt to it. But it can also change rapidly. Like, for example, if a volcano blows up or if a meteor hits the earth, that can change things very rapidly to the point where we can in that. Or if we keep, you know, pumping greenhouse gases into the atmosphere, that can also make things change too rapidly for anyone to adjust.

Yeah, it's a sensitive system, and there are a lot of things that affected, and those things all have different timescales. And they combine to make a very chaotic sort of structure of the Earth's climate. And you have these things that are very slowly, but inevitably, like, the sun increasing in its temperature regularly and then the Milankovic cycles which are actually like several different cycles layered on top of each other and so as a result you get it's very complex behavior of the earth's climate and it has affected life on our even very recently like this interglacial period that we're in only started like 10 to 15 000 years ago and obviously there were lots of humans on earth back then and that's back when there were more woolly mammoths

and there were glaciers much further down across North America, for example. And so this is sort of like in the deep history, maybe even the deep memory of our own civilization. Humans have written out some of these waves, is what you're saying. And these waves have affected human migration, right? There's all these theories about humans leaving Africa and populating Europe and doing so in several waves between ice ages, perhaps. So it's really set the whole context for life on Earth and the evolution of humanity and its migration. It's basically the frame in which we exist. Whoa.

That is pretty cool. Maybe even ice cool. It's definitely cosmic. All right. Well, we talked about different things that can maybe trigger changes in the climate. But the question we're asking today is, can a supernova from a star blowing up far away from here,

can that maybe affect the temperature and climate here on Earth? So let's dig into that idea. But first, let's take another quick break. I had this overwhelming sensation that I had to call it right then. And I just hit call. I said, you know, hey, I'm Jacob Schick. I'm the CEO of One Tribe Foundation. And I just wanted to call on and let her know there's a lot of people battling some of the very same things you're battling.

And there is help out there. The Good Stuff Podcast Season 2 takes a deep look into One Tribe Foundation, a nonprofit fighting suicide in the veteran community. September is National Suicide Prevention Month. So join host Jacob and Ashley Schick as they bring you. to the front lines of one tribe's mission. I was married to a combat army veteran, and he actually took his own life to suicide. One tribe saved my life twice.

There's a lot of love that flows through this place, and it's sincere. Now it's a personal mission. Don't have to go to any more funerals, you know. I got blown up on a React mission. I ended up having amputation below the knee of my right leg and a traumatic brain injury because I landed on my head. Welcome to Season 2 of the Good Stuff.

Listen to the Good Stuff podcast on the Iheart Radio app, Apple Podcast, or, wherever you get your podcasts. A foot washed up a shoe with some bones in it. They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases,

but everything is about to change. Every case that is a cold case that has DNA. Right now in a backlog will be identified in our lifetime. A small lab in Texas is cracking the code on DNA, Using new scientific tools, they're finding clues in evidence so tiny, you might just miss it. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha. On America's Crime Lab, we'll learn about victims and survivors, and you'll meet the team behind the scenes at Othrum,

the Houston Lab that takes on the most hopeless cases, to finally solve the unsolvable. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Your entire identity has been fabricated. Your beloved brother goes missing without a trace. You discover the depths of your mother's illness, the way it has echoed and reverberated throughout your life, impacting your very legacy. Hi, I'm Danny Shapiro. And these are just a few of the profound and powerful stories. I'll be mining on our 12th season of Family Secrets.

With over 37 million downloads, we continue to be moved and inspired by our guests and their courageously told stories. I can't wait to share 10 powerful new episodes with you, stories of tangled up identities, concealed truths, and the way in which family secrets almost always need to be told. I hope you'll join me and my extraordinary guests for this new season of family secrets.

Family Secrets. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hola, it's HoneyGerman, and my podcast,

Grazacus Come Again, is back. This season, we're going even deeper into the world of music and entertainment with raw and honest conversations with some of your favorite Latin artists and celebrities.

You didn't have to audition? No, I didn't audition. I haven't audition in like over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We've got some of the biggest actors, musicians, content creators, and culture shifters sharing their real stories of failure and success.

You were destined to be a start. We talk all about what's viral and trending with a little bit of chisement, a lot of laughs, and those amazing vibras you've come to expect. And of course, we'll explore deeper topics dealing with identity, struggles, and all the issues affecting our Latin community. You feel like you get a little whitewash because you have to do the code switching? I won't say whitewash because at the end of the day, you know, I'm me. Yeah.

But the whole pretending and cold, you know, it takes a toll on you. Listen to the new season of Grasas Has Come Again as part of My Cultura Podcast Network on the IHartRadio app, Apple Podcasts, or wherever you get your podcast. All right, we're asking the question. Can a supernova cost an ice age, which is kind of a tricky question, right? Supernovas are big, explosive, hot, deadly, impactful. But an ice age here on Earth is sort of slow and cold and, you know, freezing. So how can something exploding far away cause things to get cooler here on Earth? So the connection is still kind of tenuous, but it's sort of fascinating.

The idea is that supernovas, they don't just go boom and send out a bunch of light in the sky. they also send out dust like little bits of those supernovas that get carried along by like cosmic and galactic winds and can come here to earth and when supernovas do go boom they make sort of unique materials they make stuff that you can't otherwise make in the universe because you just don't have the conditions like stars they confuse hydrogen into helium and helium into carbon and carbon into heavier stuff all the way up to about iron but they can't make anything heavier than that because above that a cost of more energy to fuse than fusion creates. So all the heavier elements in the universe are made under much more special conditions, such as neutron star mergers, or during those moments of supernova fusion, the explosion that creates the supernova also can create weird new heavy isotopes of elements and also heavier elements. And some of those bits can fly through the universe and even land on Earth,

potentially affecting the climate here on Earth. Right. Because I think as a start collapses and becomes a supernova, it collapses, then it crunches together, and then it bounces, and then everything just kind of blows out in all directions. And that shock wave is where a lot of the heavier elements get made because things are being, you know, exploded out and compress so much, they become heavier elements. And you're saying that stuff being flung out can actually maybe reach us at some point. We know that it has reached us and we found evidence of it here on Earth. This one particular kind of element is called Iron 60s. So it's a heavy isotope of iron. This is something which can be made under other normal circumstances, but it's interesting because that's a fairly short half-life, just like two and a half million years. So if it was present on Earth when Earth was formed, for example,

all of that would have decayed away into nickel. So if you find Iron 60 on Earth, that means it was made fairly recently sometime in the last 5 to 10 million years, but there's no process on Earth that can make Iron 60. The only way we know that you can make Iron 60, 60 isn't the heart of a star, especially in a supernova. And so if you find Iron 60 on Earth, that's very strong evidence that you found remnants of a supernova here on Earth, like supernova dust has landed on Earth.

Well, wait, how do you know it's not just really old Iron 60 from when the Earth was born? Couldn't you just have a bunch of it and some of it still survive? Like, we still have uranium on Earth. We do still have uranium on Earth. Uranium is on much longer half-life than a couple of million years. the earth is 4.5 billion years, which is many, many lifetimes. This stuff has a lifetime of two and a half million years. And if there was original primordial iron 60, it would be evenly distributed and you'd see a sort of typical decay. Well, what we find when we look for iron 60 is we see

depositions consistent with an increased amount of iron 60 like twoish million years ago and maybe like another deposition like a million years ago. It really looks like we got fresh doses of iron 60. a couple of times in the recent past. You mean like we've seen basically coatings of the earth with this iron isotope? Exactly. And there's several coatings? There's several coatings.

If you just like dig down into the earth, you don't find this stuff. But on the ocean floor, you do see it. And you can see it in the sedimentary layers. You can see it like layered at certain times and not other times. And so it's really consistent with like the earth got blasted

with supernova iron 60. I wonder if you would see it on one side of the earth, you know, or not the other? Or would you see it evenly coating the whole earth? Yeah, that's a great question because we'd love to know where these supernova were, right? Which direction did they come from? And if you saw like where it landed on the earth, you might be able to like reconstruct that, not just from which side it's on, but like where is it more dense? And unfortunately on earth, these things tend to get swirled around a lot.

Like on the ocean floor, things get mixed around. And so you can tell it's there and you can tell what year it was deposited, but, you know, over millions of years, these things do get swirled around and spread out. But if we went to the moon, the moon is a much better place to keep these sort of ancient geological records because, you know, there's no weather on the moon. There's no water. There's no air. And so where things landed on the moon is pretty much where they still are. So the moon might have a great snapshot if you measured the iron 60 on the surface of the moon to figure out which direction these things came from. Whoa. Well, we've been to the moon and we've gotten samples from there. What do we find in terms of this iron?

We didn't find very much, but the samples are not really the kind you would need to answer this question. You know, Apollo landed on the near side of the moon and much more likely these things landed on the far side of the moon because it's facing out. And so we'd need much broader sampling also to like reconstruct the direction. And so if you wanted to answer this question from samples on the moon, you'd need to sample very differently from the way Apollo did. So we don't really have the data we would need to answer that question. One more reason to go back to the moon. So the Earth has gotten a few dustings of this iron from potentially supernovas.

What's the connection to an ice age then? So there's a couple things. One is they can look at the timing of the supernova. And it looks like there was a string of supernova that went off in the last 10 million years in our galaxy. It's like a blob of deposition of Iron 60 from like 1.7 to 3.2 million years ago. And then there's another deposition like 2.5 million years ago and another one like 0.8 million years ago that they think are consistent with supernovas that went off like around 300 light years away from the earth. And the timing of these things kind of lines up with the timing of the ice ages.

So if you look at the history of the climate on the earth and you look at the history of these supernova, you can like kind of line these things up. Now, that's just correlational, but it's intriguing, and it makes people wonder, like, hmm, could the arrival of this iron 60 on Earth somehow trigger climate effects which lead to ice ages? Whoa. I guess maybe one question people might have right now is these supernova were super duper far away, 300 light years is gazillions of kilometers away. Could there still be enough iron in that explosion this far out? Wouldn't it be super diluted and spread out? would actually be a significant amount that we could see? It's a great question and highlights the incredible numbers that are going on here.

Like, first of all, when you make a supernova, the amounts of material are vast because supernova come from really big stars, right? So you're starting with an incredible number of atoms. But then, of course, as you say, space is huge and we're far away from these things. So how are we getting any of them? And the answer is that we're not getting many. The number of iron 60 atoms we've recovered, numbers in the thousands. So we scour the planet for these things and people have done these incredible missions to the bottom of the ocean.

We don't have a lot of examples. We have enough to reconstruct the timing of these things to say something about which direction maybe they were coming from. But we don't have a large number of examples, no. Meaning this is a very faint signal. It's a pretty faint signal, but it started out so bright and so intense that even this far away, we can pick it up. Now then how can this iron affect the climate here on Earth? So that's something people are more speculating about and trying to understand. It's not a solid model here.

But you can imagine that the arrival of heavy metals in the atmosphere could change the way things circulate and the way things nucleate and the atmosphere chemistry, which is very complicated. And so there isn't like a very clear argument here yet. I mean, I was reading some papers that were kind of hand wavy. But the general idea is the atmosphere composition is an important component of understanding the climate and changes in the atmosphere can. change the climate. We know that's true. And so the question is, can iron 60 or how much iron 60 would have to arrive to trigger a change in the climate that might give you an ice age? That question is not answered. Right. It seems like you wouldn't get, I mean, if we're talking about thousands of atoms, that doesn't seem like a lot enough to trigger an ice age. But maybe the

Superman would send other things besides iron, right? Like maybe it'd send other elements. Absolutely. A ton of other elements, perhaps. And we have found thousands of atoms. Of course, we have a tiny detection efficiency, which means there are many, many more atoms actually arrived on Earth. And you're absolutely right. The Iron 60 is just like one of the easiest things to identify, but along with it must have come all sorts of other debris from the supernova. And when you get unusual weird cosmic dust from space, that might trigger changes in the atmosphere. But it's kind of speculative. I think the most suggestive piece of evidence is the coincidence between the timing of the Ice Ages and the timing of these recent supernova. Although it's hard to tell,

if that's a coincidence or not. I see they seem correlated. They seem to be happening at the same time, but we don't know how yet or how that's even possible. Exactly. And, you know, this is the process of science. You see this weird effect. You wonder if they could be connected.

You look for a mechanism rather than just saying, oh, look, it happened at the same time, therefore one caused the other. Try to dig into it and understand, like, how could that be? Is there a way that could really happen? And how could we check that? And so some people are working on that right now, like trying to understand what kind of supernova

may trigger a change in the atmosphere. Interesting. It made me think that, you know, these supernovas happen really far away, right? And they're huge in which, and they maybe affect the entire Milky Way galaxy or a big part of the Milky Way galaxy, in which case, like one of these supernova is exploding could maybe trigger an ice age and a whole bunch of planets around that star, right? Yeah, absolutely. And when the supernova happens, it like sterilizes the nearby planets.

But it's cool to think it could have a more subtle effect. on even further away planets, right? It can change the climate of those planets, which could really affect the evolution of life on those planets. Like, maybe life is more likely to become intelligent when there are ice ages or when this oscillating ice ages and warm periods. Who knows, right?

But supernovas definitely have a rippling effect on the whole history of the galaxy and that changes the whole frame for life everywhere in the galaxy. Yeah, it's definitely a cool effect. And like you said, like maybe it's possible that the only reason we evolved, is because of a supernova.

Like maybe if that supernova hadn't happened and sent all this material here, we wouldn't have evolved. Yeah, or we could have evolved very differently, you know, migrated differently, had different patterns and paths if the climate were different. And so life on Earth could be vastly different

without that supernova. Yeah, without that iron. In which case, it means, Daniel, I think, that we're all Iron Man. It's not just Tony Stark. That's right. Oh, snap.

You don't have to run a marathon and bike 50 miles and swim 10 miles all the same time to be Iron Man. You just got to live here on Earth and listen to the podcast. And or build an armor, yes, a robotic armor. Awesome. Well, I'm looking forward to riding my own saber-tooth cat to work. Not, you're looking forward to jumping your own prehistoric shark, right? Yeah, that's right, exactly. Sabretooth shark, yes.

Or maybe we should start a new meme or term, right? jumping the saber-toothed tiger. We're jumping the wooly mammoth. Oh, that sounds even better. There you go. Yeah, we really jumped. Well, that podcast was great. But then it jumped the woolly mammoth and, you know, now it's even better.

Yeah, well, maybe we're entering the vast podcast Ice Age. Yeah, things are definitely cooling a little bit here. All right, well, another reminder of how precarious life here on Earth is to all of these cosmic events that are happening all around us and maybe hopefully make you appreciate the fact that we are here talking about these things and that maybe that fact is only possible because of a certain string of events that happened billions of years ago. Our curiosity to understand the universe continues to burn hot even if the heat of those stars

eventually causes a nice age. All right, we hope you enjoyed that. Thanks for joining us. See you next time. For more science and curiosity, come find us on social media where we answer questions and post videos. We're on Twitter, Discord, Insta, and now TikTok. Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio.

For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. Get fired up, y'all. Season 2 of Good Game with Sarah Spain is underway. We just welcomed one of my favorite people, an incomparable soccer icon Megan Rapino to the show and we had a blast. Take a listen.

Sue and I were like riding the lime bikes the other day and we're like, we're like, people ride bikes because it's fun. We got more incredible guests like Megan in store plus news of the day and more. So make sure you listen to Good Game with Sarah Spain on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

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