Daniel and Kelly’s Extraordinary Universe - What Is the Hottest Thing In The Universe?

Episode Date: May 28, 2019

How hot can it get? Is there an upper limit to temperature?  Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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It's time to tear the paper ceiling and see the stars beyond it. Find out how you can make stars part of your talent strategy at tear the paper sealing.org. Brought to you by opportunity at work in the ad council. Hey, Daniel, do you know the concept of absolute zero? I don't mean the vodka. I mean like, you know, the concept that there is a cold. this possible temperature in the universe. Yeah, and I think that's super awesome.

I love when there's something in physics that has an extreme to it. Like, beyond this point, it is impossible to go. Extreme physics! I feel like we should have a heavy metal guitar sound there. Yeah, this podcast brought you by Mountain Dew. Rush the physics, dude. But, you know, I was asking because I was thinking about what is the opposite of absolute zero temperature?

Like, is there a maximum temperature in the universe? hottest thing ever or possible? Well, if there's a hottest thing ever, it's probably somewhere here in Southern California. But it's a fascinating concept, like, is there a point where after you pump in more energy, it just doesn't get any hotter? It's an incredible idea. It's too hot

to handle. Or for the universe to handle. That's right. Yeah. Or maybe, you know, after you pump in too much energy, like it just blows up, or it crosses the singularity, or restarts the universe. It makes a glitch in the matrix or something. Well, at some point, wouldn't you hit some sort of you know, light speed kind of maximum limit in the universe?

Yeah, I think the physics police would pull you over and be like, what are you doing? Explain to us how this makes any sense. You're way too hot, sir. You're way too hot. You've got to cool it down a little bit. Leave a little room for the rest of us to be attractive. That's right, yeah.

Too much sizzle, exactly. Hi, I'm Jorge. I'm a cartoonist and the creator of PhD comics. I'm Daniel. I'm a particle physicist, a part-time podcast host, and I've never created an online comic. But I did once write a book about all the things we don't know in the universe together with Jorge. And it's filled with his hilarious comics. It's called We Have No Idea. So you only podcast part-time, Daniel? That's right. Only 90 hours a week. That's a part-time schedule. I have this podcast, and I have 89 other podcasts I also do.

I thought you were going to say that's how much editing this podcast needs to get it down to 40 minutes. That's how much research is required to boil down all these incredible insights into just one hour of time. Well, welcome to our podcast. Daniel and Jorge Explain the Universe, a production of IHeart Radio. That's right. And in our podcast, we try to take some topic of general interest, a question people, ask something that everybody wants to know about the universe and break it down in a way that actually makes sense to you and along the way maybe get you to laugh. Yeah, so today on the podcast, we're doing part two

in our unofficial, informal series of universal extremes. That's right. We thought it would be fun to take you out of your situation, to pull you out of your ordinary everyday life or maybe you have a very exciting life and think about the biggest, fastest, nastiest, hottest, hottest, hottest, craziest things in the universe. That's right. There's probably some skateboarders out there or some ex-game athletes that are like, you know, my life is pretty extreme already, man.

They have no idea. There's somebody out there in the universe surfing on black holes and riding the shockwaves of supernovas doing crazy tricks that nobody could ever imagine. Yeah, so a few weeks ago we did, what is the biggest thing in the universe? And today, we are tackling the subject of what is the hottest thing? in the universe. Answer, you. You are the hottest thing in the universe, Jorge. That's right. Oh, no, no, no, not me.

The person listening to this, right? That's right. You, our listener. You are the hottest thing in the universe. You look great today. Yeah, I don't need any flattery, but, you know, it'd be nice to bribe the audience a little bit. That's right.

Not that we're spying on you, not that we're stalking you on social media, but have you been losing weight? You look great. Yeah, totally, super hot. But, you know, the universe is filled with all sorts of crazy stuff. Here on Earth, we have some temperature variations. But, you know, even inside our Earth, the temperatures get crazy hot, crazy high numbers that are sort of hard to understand.

And so we thought it would be fun to take a tour of the universe and to think about all the hot places. Like, where in the universe does it get hot? Where in the universe is the craziest, hottest, nastiest furnace that you can imagine? That's right. And it's pretty cool to think, I think, about these extreme examples because it really kind of pushes your mind, right? It sort of expands your understanding

and your awareness of how crazy things can get. Yeah, and I think you'll be pretty surprised by the answer. I don't think that what physicists think is a hot place in the universe is the kind of thing that anybody would imagine. I was kind of surprised when I was doing some reading about this. Oh, wow, really? So the hottest thing in the universe is maybe the most unexpected. It's unexpectedly hot.

Yeah, that's right. And when I was thinking about this topic, I was thinking about how often in physics we have a term that we use to describe something, which is also a term in English. You know, like temperature is definitely something we're aware of, right? You know what hot and cold means. You touch things. They burn you or they freeze you or something.

But sometimes in physics we create technical definitions for things like temperature, because we want to understand it, right? We want to describe it, like where does temperature come from? How does it work? What makes something hot? What makes something cold? But then this thing happens where the technical definition we use in the science, scientific community deviates a little bit from like the familiar term that people use in their

everyday life. And sometimes they can even come into conflict. Is this one of these terms where physicists, so who came first? Really, the popular conception probably came first, right? Yeah, the concept of temperature is age old, right? People have been talking about, people have been dropping hot coals on their toes and screaming curse words in thousands of languages for thousands of years, that's for sure. And then people were studying heat and thinking about like, you know, what is heat and how does it transfer between things? And they had no idea, like, is it a flow? Is it a liquid? Is it this invisible? This thing or that thing. So the study of temperature is just a few hundred years old. But the experience of it,

right? The knowledge of hot things and cold things, that's age old, right? Yeah. Well, let's get into the definition of temperature in the episode. But first we were wondering what people thought out there, all of you listening to this, what you guys thought is the hardest thing in the universe. Yeah, I thought this would be interesting to see what people think about it. And I gave them a little bit of extra time on this question. I prodded them to think about it a little more deeply if they didn't seem like they gave me an insightful answer right off. So I walked around the campus of UC Irvine and I asked people, what's the hottest thing in the universe? And, you know, here I was obviously digging for compliments, but nobody said me, right?

Nobody said you. Nobody gave me a compliment on how I looked that day. Maybe it's just what you were wearing. If you had worn something else It's sandals and shorts every day around here So you walked around and asked people What is the hottest thing in the universe And generally what did people say?

Right, well listen to their responses And you can tell What's the hottest thing in the universe? The sun Our sun? Like the center of it or the surface Or? I'd say all of it

Okay Probably like one of those big The big stars that you see on like the Twitter videos where it's like they get bigger and they get bigger. I don't know what they're called. Cool. Scary names. Super, super giant stars?

Yeah. All right, cool. In the middle of some really dense star somewhere. Okay, so you think the center of star is hotter than like its surface? Yeah. Okay, cool. I'd assume it's not the sun since you're asking me this. But I'll say the sun since I can't think of anything else.

All right. The whole universe? Yeah. I don't know. Probably like a planet somewhere. Okay. I don't know. Um, we'll call it the, um, I don't know, the center of a sun.

Center of a sun, okay, cool. Although I don't think that's right. You don't think that's right? No, because some of the plasas, they're saying, are actually hotter than the sun that we have here. So that can't be right. Um, yeah. Okay. The center.

The center of the universe. Where is the center of the universe? No idea. Okay, cool. The sun. Our sun? Yeah. Cool, like at the center of it or on the surface or somewhere in the middle.

Somewhere in the middle. okay cool all right so pretty much people said uh the sun a lot of people thought it was the sun yeah yeah people thought it was the sun and like that's pretty good like the sun definitely a big hot thing so not a terrible answer right but i wanted people to think a little more broadly and sometimes i need little people and it's like you know how about the whole universe but still people are like okay maybe a different sun like another star a hotter sun and you know i don't think we should be insulting our son. I think our son looks great. I don't want to do anything to disturb it.

You know, it's operating steadily for billions of years. Bright, beautiful, you know. And it is sort of losing weight every day, isn't it? Yeah, yeah, exactly. Despite his brilliance. And people, I guess, generally feel like that must be so hot that nothing could be hotter, right?

Oh, I see. So you were priding them to think bigger. Like most people said the sun, but then you would ask him like, no, I mean, like the entire universe. Mm-hmm. Mm-hmm. Like, think for a minute. Like, is the sun really the hottest thing? Isn't there something else crazy? I like to think that if it was sort of me and somebody came and asked me about it and I'd done no thinking or no research or whatever, that I would say something like,

I don't know, but it must be something hotter than the sun. Because I have this feeling like there's always something crazy out there. There's always something out there that blows our minds or surprises us or is different or bigger or denser or nastier or faster than we could ever imagine. You mean if so many approach you on the street, do you imagine that you will just say the most correct and cleverest thing possible? No. No, I don't imagine I would have the answer. I think I would say, I don't know, but it must be hotter than the sun, right? Because I can't imagine that the thing that's in our neighborhood happens to be the hottest thing in the whole universe, which is just so crazy big. Oh, I see. You think that maybe they weren't thinking that there could be something hotter than the sun.

Yeah, that seems to be the impression people have, that the sun is basically peak hotness. Well, maybe they didn't just, they weren't just thinking that our sun is the hottest, but I think maybe they were thinking like this inside of a sun that it can't possibly get any hotter than that. Yeah, and you know, they're not too far off. The sun is pretty dang hot, but it's like orders of magnitude colder than what we're going to talk about. Well, great. So maybe first before we talk about like temperature and numbers and how hot things are, let's talk about what those numbers mean. So that when you hear like a really big number, you can understand like what does that really mean about what's going on? inside that thing. Like, what really is temperature?

Like, let me ask you, Jorge. How would you define temperature? How would I define? You know, I mean, I know the scientific answer, which is related to, like, kinetic energy, but, you know, I think on an everyday basis, it's just sort of like, it's a feeling, you know? To me, I think it's a feeling, whether I feel hot or whether I feel that something is hot.

You know what I mean? Like, to me, it's not an abstract number. It's more like a feeling. And it could maybe be relative, like, something, if I feel hot, or something, if I feel hot and the person next to me doesn't feel hot, then that's the difference of opinion. Yeah. And our experience of temperature, you're right, is definitely relative, right? What you feel is actually is the air or water around me hotter or colder than I am, right? We don't have an absolute sense of temperature. You can do that experiment where you put like one finger in a hot cup of water

and another finger in a cold cup of water and then put them both in a lukewarm cup of water and your two fingers will send you two different messages. One will say, this lukewarm water is actually hot and the other one will say no it's actually cold because what you're measuring is the relative temperature to your finger right right and also the sense that you've adapted to it as well right like you get used to certain temperatures and so and then they don't feel hot or they don't feel cold that's right yeah like you jump in the pool it feels cold for a moment and then you're you know your skin temperature changes a little bit and you get used to it and then it doesn't feel cold anymore so our experience of cold is mostly about relative temperatures right it's it's actually

about is heat being transferred to us or is heat leaving our body. Right. And so it's a very kind of feeling-based kind of definition, but I know that there's an official physics definition of it, right? There is an official physics definition, but, you know, it's not really super well defined. It's a bit surprising. It's not something that's exactly nailed down. Like, you can define temperature for an infinite number of particles that have been sitting in a box for an infinite amount of time. And that's about it. Like, everything else it's like sort of rough and hand-wavy. What do you mean?

Well, temperature, the way they define it, is a measure basically of how much energy is being stored in a system of particles. But those particles have to be in equilibrium, meaning you can't, like, have hot spots and cold spots. It needs to have all washed out and all the edges and unevenness needs to have smoothed out

because temperature, in a physics point of view, is the description of a distribution of the energy of particles in equilibrium after everything has sort of calmed down. You said a lot of words there, Daniel. I think what you're trying to say is it's like an average temperature. The thing about temperature is that there's sort of two different ideas at play here, right? One is the quality of temperature.

This is the feeling that you were talking about, the experience we have, right? Which is really more about like the transfer of heat between hotter things and colder things. That's what we're experiencing. And that's also what thermometers are measuring, right? A thermometer gets into equilibrium with the thing it's measuring. the heat transfers from it to the thermometer. But then scientists spend a lot of time trying to understand, like, how does that arise? What is the microscopic property of something?

How does that property change when things get hot or cold, right? What is going on inside this stuff when it gets hot or cold? How can we define temperature theoretically and understand it rather than just measuring it, right? That's what physicists want to do. So they came up with a way to define temperature, actually two different ways, at least. One way is related to like the mean energy, the particles, right? And the other is the relationship between the energy of a system and its entropy. Okay, so it gets kind of technical.

But the thing to understand about these definitions are you can't actually measure these theoretical quantities directly and exactly, right? You can't go in and measure the energy of particles individually. Right. What you can do is measure the heat flow using thermometers, right? So these theoretical things are connected to what we measure, but they're not exactly the same thing. And the other thing is that these theoretical concepts, they only really make sense for a system of particles in equilibrium because they're statistical concepts.

So what that means is that the theoretical definition can deviate from our intuitive experience of temperature. Some things, if they're not in equilibrium or they don't have enough particles to be called like a system, they don't even really have a well-defined temperature or one that can be actually measured or practically measured. What do you mean? What doesn't have a temperature?

Well, for example, one particle. Like a single particle doesn't have a temperature. Like, what's the temperature of a single particle? It's not defined for physics temperature, right? There's like, you know, person temperature, the kind of temperature you and I talk about when we get into a pool. But when we're talking about temperature from like a physics point of view, a single particle doesn't have a temperature because it's the property of a system. Right, but what if your system only has one particle? Then it doesn't have a well-defined temperature. What do you mean? What if there's a cube in space that only has one particle?

You can't say that that cube has a temperature. You can't, that's right. And there's even weirder situations that you can't say have a temperature. Wait, what about two particles? How many particles do you need to have a temperature? That's not even well defined. Technically, you need an infinite number because you need to be in total thermal equilibrium. That's the thing.

Temperature is only well defined for things in thermal equilibrium, which means there's no hot spots and no cold spots. Everything is sort of evened out, right? You had an infinite amount of time for all the hot and the cold to wash out, right? So you're saying nothing, technically nothing can have a temperature because nothing can have infinite particles. Yeah, but, you know, like a drop of water has 10 to the 23 or so particles in it or 10 to the 21 particles in it. That's a good approximation of infinity.

And so, yes, you can talk about the temperature of a drop of water. You know, it's an excellent approximation of infinity. One particle? No. Two particles? No. Five particles? No. How many particles do you need before you can call a temperature? that's not even well defined. And then also how much do you have to wait

until you can claim that it's in equilibrium, right? That's right. So for people who don't know what I mean when I say equilibrium, take for example, say you have like a bag of gas and that gas is at like 10 degrees. You have another bag of gas that's at like, I don't know, 90 degrees or something.

Now those are both in equilibrium. They have temperatures, right? Say you put them together into another bag, right? What's the temperature of that new gas? What you might say, I don't know, the average of 10 and 90, well, that's 50, right? But until those wash out and all the smushes around, physicists say there is no temperature.

Like, you just can't define it. So that's frustrating, right? Because it, like, gets in your mind. You're like, that doesn't make any sense. And you're right, because you're using, like, the temperature that you think about in English, right? Temperature is a word in English. We have defined this other thing, you know, call it physics temperature,

which is very closely related to English temperature, right? is not exactly the same thing. And later on, I'll give you an example of something which physics says is super-duper-hot, it has a huge high-temper-value, but if we dropped you in it, you would freeze. Hmm. There is no true temperature, technically, but, you know, we can't work with ideals, so we kind of approximate it. That's right, exactly. And for anything more than, you know, a billion particles, it's not a big deal.

fine. But if you want to talk about one particle, two particles, three particles, there isn't really a definition of temperature. Man, I feel like this whole episode could have just been like, hey, what is temperature? And we could spend an hour talking about this. I know. That's a pretty hot rabbit hole. Yeah, it's a hot topic. So you're saying it's the mean energy, but I've heard it's the mean kinetic energy. What's the difference? Well, kinetic energy applies to speed, like how fast are these particles zipping around? And it makes a lot of sense. intuitively, when you think about an object like in a solid, things are colder and things and they're not moving around as much.

Maybe they're even trapped in a lattice in a liquid. Things are moving around more, which allows a liquid to flow in a gas. Things are zipping around really fast, so it's related to the speed. But particles can store energy in other ways. They don't just have to move quickly. They can also like spin, or, you know, they can vibrate if they have complex chemical bonds, et cetera. So they can store energy in other ways.

So really temperatures related to all the ways a particle can store energy. The speed is a great one. Oh, I see. Okay. Yeah, and it makes perfect intuitive sense. And so as you're thinking about these things being hot or cold, you know, think about them wiggling more, right? Like the way temperature arises, the reason things are hot

is that the particles in them are wiggling more. And that's also like why you get burned, you know? You get burned because you touch something hot. Those particles are wiggling a lot, so they're bouncing off your finger and depositing a lot of energy, which is why your temperature heats up, right? It wiggles the particles in your finger.

That's how heat is transferred, right? Okay, cool. All right, so that's a definition of temperature. It only took us 20 minutes to get here. I know these things sometimes are surprisingly subtle. Yeah. So let's get into then now the universe, and let's talk about like the coldest thing and the hottest thing.

But first, let's take a quick break. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently the explosion actually impelled metal, glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. terrorism law and order criminal justice system is back in season two we're turning our focus

to a threat that hides in plain sight that's harder to predict and even harder to stop listen to the new season of law and order criminal justice system on the iHeart radio app apple podcasts or wherever you get your podcasts my boyfriend's professor is way too friendly and now i'm I'm seriously suspicious. Oh, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot.

He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them.

I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Get fired up, y'all. Season two of Good Game with Sarah Spain is underway.

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on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Presented by Capital One, founding partner of IHeart Women's Sports. All right, we're talking about the hottest thing in the universe. And so let's take a tour of hotness in the universe. I feel like we're back in the 90s. Remember that website? Remember that website? Are you hot or not? I think that website, even mentioning that website,

is sexual harassment for all of our listeners. Oh, boy. Yeah. The 90s were pretty fraught with bad ideas. Yeah, people made some bad choices in the 90s. Yeah, exactly. But, no, I do remember that website. Not that I ever participated.

and I didn't objectify anybody in the internet, but I did hear about that website from people. Oh, I see. You only heard about it. Got it. Absolutely. All right. Well, let's start with that on Earth. What are some of the hottest things on Earth?

Right. Well, first of all, let's clarify what we're talking about. Let's do everything in Celsius, right? So for those listeners in the U.S., you have to get calibrated, remember. Let's spend 20 minutes talking about Celsius versus Fahrenheit. No, we're not going to debate it. We're just going for Celsius for the world. listeners. Zero degrees Celsius is the temperature at which water freezes, right? And 100 degrees,

of course, is where water boils. And, you know, somewhere in the middle is you and me. Like, our body is about 37 degrees Celsius. Right. And you can have things colder than zero Celsius, right? That's right. Absolutely. You can get down to like negative 273 degrees. That's absolute zero. Right. And that's where the particles, the molecules, the things in your thing have no kinetic energy. The Things in Your Thing. Is that a Dr. Seuss book about physics? Yeah. The Things in Your Things.

The Universal Things in Your Universe. Oh, the Things that will wiggle in your things. Yes. Exactly. Absolute Zero is when the things are doing no more wiggling, right? They're just totally at rest. There's no kinetic energy. No kinetic energy.

You have mass. You can have energy stored in the particles in atoms, but it's just not moving. That's right. Exactly. It's an absolute zero. So that's negative 273 degrees C. and then zero is ice. 37 degrees C is the human body.

And then the hottest person ever is 46.5 degrees C. That's like the hottest anybody ever got with a fever. Wait, that's recorded in the history books? Yeah, exactly. Oh, wow. What happens if you get hotter than 46.5? Well, I think your brain cooks and you turn into somebody's meal, you know. I don't think your brain can really survive much more than that.

But this is not a biology podcast or a cannibalism podcast. Right. So that's the hottest fever anyone has ever gotten. And survived, I think, is the caveat. And survived, exactly, yes. And then the hottest place on earth, you know, I think there's a tight race here because Death Valley, I've got to give my props

to Southern California, Death Valley is one of the hottest places on Earth, but it's just edged out by this desert in Iran called the Lute Desert, and it reached 71 degrees Celsius, which is really smoking hot. that's the temperature you would feel if you were standing in this desert exactly and that is the hottest temperature ever recorded on the surface of the earth

is that the hottest air temperature do you know what I mean because there's definitely hotter things on earth like my frying pan is hotter than that but you're saying like if I just put a thermometer and hold it up in the air not touching anything or you know not touching any stove that's the hottest place you would feel on earth yeah no I think I'm I'm composing an email right now to the Guinness Booker World Records to consider your frying pan to be the hottest place on earth. Yeah. No, you're right. We do create things on Earth that are hotter, but the hottest naturally occurring air temperature. Man, there's so many caveats just to like how to define the hottest place on Earth. Yeah. So it's air temperature. Hotest air

temperature in Earth, barring any sort of like standing next to wildfire. That's right, exactly. It's 71 degrees C. And you might think, well, that's pretty hot, right? But, you know, gets hotter, like, even on the moon, on the moon, the average day-time temperature on the moon is 101 degrees C. I'm just nodding along because I'm used to Fahrenheit, so I'm going to take your word that that's pretty hot. That's the boiling point of water, dude. Like, you put water on the moon, like, it just boils.

It's crazy, right? Well, it would boil anyway because there's no atmosphere, yeah. So maybe that's not surprising. On Earth, at our regular air pressure, 100 is when water would boil. Yes, exactly. So, you know, 212 degrees Fahrenheit, that's a pretty hot temperature for the surface of the moon. And then here's, this is one of my favorite ones, the hottest temperature ever survived by a living thing. That's 151 degrees Celsius, right?

That's crazy hot. Yeah, that's, like, much hotter than the boiling point of water. That means that whatever this thing is, like, it's... it really got fried. And that's, of course, our friend, the tardigrate. These crazy little water bears that can survive, like, outer space and being frozen. They're, like, the hardiest thing on Earth. Right.

There are tiny little microscopic bugs, right? Yeah, exactly. And if you've never heard of a tardigrade, you should Google them. They're incredible. Yeah, scary looking, though. I think they look friendly. I'd like to have dinner with the tartary. Really?

If you made a life-size tardigrate, you wouldn't run the other way immediately. they look like a big snuggle I mean they're on socks look like a big pillow I would jump onto a tardigrade and treat it like a bean bag so that they can survive 150 degrees Celsius

yeah that's the hottest temperature ever survived by a living thing that's a pretty impressive record right so you could put this in boiling water and put it in boiling water under pressure and it would still survive that's right exactly but then leaving the surface of the earth

the hottest spot of the hottest naturally occurring spot on the solar system is the surface of Venus, which is 460 degrees Celsius. And that's because Venus has such a thick cloud layer. It's basically climate change gone crazy. All the carbon dioxide in the atmosphere means it's a huge blanket and just soaks up the sun. That's why Venus is hotter than Mercury because it just holds on to the sun's energy and cooks and cooks and cooks. Cool. And that's in outer space. Well, it's on the surface of Venus. Right. That's like the air temperature if you were standing on Venus.

That's right. If you weren't cooking eggs, but you were just holding up a thermometer on the surface of Venus, that's what you would measure. Right. Okay. Got it. But then if you, you know, went to the sun, like a lot of people said, okay, the sun is the hottest thing, right? Well, it's true. The sun is really hot. If you jump to the surface of the sun, then it gets up to like 5,500 degrees Celsius. Wow. That's a lot. Yeah, it is. It's really hot. But, you know, there are places here in the earth that are

even hotter than the surface of the sun. Like, we talked once in a podcast episode about how the center of the earth is this crazy liquid iron, right? Well, the center of the earth is 6,000 degrees Celsius. So that's hotter than the surface of the sun. So the molecules at the center

of the earth are moving faster than the molecules on the surface of the sun. Yeah, that's right, exactly. But the sun is a huge variation. Like the surface of the sun is pretty hot. But the corona, like the atmosphere around the sun, is even hotter.

hotter than the surface. Yeah, it's weird. On the surface, it's 5,500 degrees Celsius, but the atmosphere of the sun, the corona, is a million degrees Celsius. Just because things are moving faster, you know, they're just more chaotic. Yeah, you know, I don't even think it's that well understood. Like, the dynamics of the sun and how that all works is something that we're still really studying. In fact, they're sending a probe right now to go, like, orbit the sun and try to make a bunch of measurements

because the sun is a pretty big mystery. It has this crazy magnetic field we don't understand. and these crazy flares and it's a pretty big deal so people are trying to understand the sun we should do a whole podcast episode about mysteries of the sun wow so if you grew up in the earth core

and then went to visit the surface of the sun you'd be like oh man this is like minus 500 degrees Celsius cold that's right you have to pack a jacket but first you'd have to get through the sun's atmosphere at a million degrees Celsius so that'd be pretty tough oh I see really it goes from a million degrees to 5,000 degrees

yeah it's crazy right like how can those two things coexist anywhere near each other. It doesn't really make sense. But I think a lot of that is because the sun is expelling all this energy, right? And so the gas in the corona gets heated up. But also, I think there's something going on here by the definition of temperature, right? The sun's corona is not as dense as the surface of the sun. And some of these things that are really hot are not actually very dense. Yeah, that's kind of what I was alluding to earlier, right like you can if you take the temperature of something that doesn't have a lot of particles or molecules in it it can still have a temperature it just wouldn't have a lot of things in it yeah so we can have a high temperature without having a lot of heat right

like there's not a lot of heat to deposit on you if you put yourself in a box with a very dilute gas that's really really hot but there's not that much gas in there right then it's not going to cook you because it's not that much energy being deposited on your body for the energy deposit on your body the particles have to hit you and transfer their energy but if there's not that many particles, there's not that much to do the cooking. Oh, I see. So, wait, when you say temperature is the average kinetic energy, what do you take the average of? Like, particles? You know, you take the total energy and you divide by the number of particles. What does it mean to take the average? Yeah, it's a property of the distribution, actually.

So, yeah, what we're looking for is the mean of that distribution. Yeah, but, you know, that's a dangerous. We could go down that rabbit hole the definition of temperature for another 20 minutes. So be careful. Well, I'm still confused. I know. It's tricky. It's tricky.

But let's keep going. Then you come back to on Earth, right? And it turns out that we can generate things on Earth that are even hotter than the corona of the sun. For example, when we still use to test nuclear bombs, like on the surface of the Earth, at the core of a nuclear explosion, you get up to like 10 to 50 million degrees Celsius, right? These are crazy high numbers that are hard. even think about. Okay, so that means that the molecules at the center of the nuclear explosion are moving super duper, duper, duper fast. Yeah, exactly, super duper duper fast. And that number

50 million degrees Celsius, you know, that's comparable to like really hot astronomical stuff. You know, like, for example, when a supernova happens, right, a star goes, goes, novi, it explodes. Well, that's a similar temperature. Like, it's 50 million degrees Celsius in the gas that's expelled by the supernova. Right. Wow. That's when a star collapses, right? That's right. The star collapses and then explodes. And, you know, what's left is like a little neutron star or a black hole in the center, and the rest is all this gas that's spelled out, that's spewed out, and that's a 50 million degrees Celsius. Okay, cool. This surprised me a little bit. It turns out that, like, supernovas are not even the hottest thing out there in

space, even though they're hotter, you know, that our sun and they're hotter than nuclear bombs going off. The hottest thing that's out there in space is stuff like the intercluster medium. That's just like all this gas that's between galaxies. You know how galaxies have a huge amount of gas in the mixed stars, et cetera? But between the galaxies is not totally empty. We did a whole podcast episode about like how empty is space. And then there's these tendrils of gas that connect the galaxies together. And they're pretty thin.

It's like not a whole lot of stuff out there. You need like a thousand cubic meters of space just to have one particle. But they are really, really hot. Like, those particles are really moving. And the temperature number you get is 100 million degrees Celsius. Wow. Are they all moving in one direction, you know, like wind? Or are they just sitting in place vibrating really fast?

I think there are currents because the reason that this stuff is hot is that they're getting heated, right? They're getting heated by like the black holes at the centers of these galaxies that are pushing on them. And the crazy, like, you know, rubbing of huge clouds of gas. that's spewing stuff out. So I think they're getting, the source is the galaxies. Probably they're all spewing away from the galaxies. But they're probably our currents

as these galaxies spin and things hit each other. It's probably really complicated. Oh. So it's actually kind of in the empty spaces between galaxies that we see some of the hottest stuff in the universe. Yeah.

And that's the weird thing. It seems empty. And if you went out there and looked for particles, you wouldn't find very many. But if you ask a physicist... You would get burned to a crisp, is what you're saying.

You would not get burned to a crisp. because there are hardly any particles out there. And you can ask a physicist like, hey, what's the temperature out here? And they'd be like, hmm, it's a hundred million degrees Celsius. But if you got dropped there without a space suit, you would not get burned. You would freeze. I see. There are a lot of hot pins out there in that space.

But if you stood there, you wouldn't, you would hardly feel them. Exactly. They're there, and they're really hot. Yeah. You wouldn't get hit by enough of them to keep you warm, right? You would radiate out all your heat into the pretty empty space. and freeze into a block of ice, right? And you wouldn't get warmed up by the 100 million degrees Celsius plasma that surrounds you

because it's hardly any particles hitting you. I see. But the average speed of those few that are there is a lot. There just wouldn't be enough to really burn you or feel them. Exactly, yeah. Wow. All right. So just zoom back to Earth because it turns out that here on Earth,

we've created some pretty crazy hot stuff. and that's not just your frying pan. But when we collide particles at the large H-Gon Collider, we very briefly create a situation where the particles have a huge amount of energy. Okay. But again, it's not about energy. You're saying you create a situation where the particles are moving really, really, really, really fast.

Yeah, the particles are moving really, really, really fast. But you don't really consider the temperature of a particle, right? So if you say, like, what's the temperature of a proton zooming around the large Hedron Collider? We can't talk about the temperature of one particle. but sometimes in the large Hedron Collider we don't just collide protons we take big stuff like the nucleus of a gold atom

or a lead atom and we smash those together and the reason is that they try to break up the matter and create this condition that they think existed in the early universe it's called a quark gluon plasma so when you break the proton up and the corks and the gluons have so much energy that they're not bound anymore they're just like floating around free

so you smash enough particles together so, you know, lead and gold atoms have hundreds of protons and neutrons in them, then very briefly you create this thing which they think is in equilibrium so you can define the temperature. It's like, you know, bounced around for a few, you know, bill a seconds. And this thing, they say, gets to five and a half trillion degrees Celsius. Trillion with a T. Trillion with a T, exactly. Like, that's a big number.

Well, let's get into now the hottest, the absolute champion, most hot thing in the year. universe. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass. The injured were being loaded into ambulances, just a chaotic, chaotic scene.

In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and order, criminal justice system is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit.

Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust. Now he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor and they're the same age.

And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, podcast or wherever you get your podcast. Get fired up, y'all.

Season two of Good Game with Sarah Spain is underway. We just welcomed one of my favorite people and an incomparable soccer icon, Megan Rapino to the show. And we had a blast. We talked about her recent 40th birthday celebrations, co-hosting a podcast with her fiancé Sue Bird, watching former teammates retire and more. Never a dull moment with Pino.

Take a listen. What do you miss the most about being a pro athlete? The final. the final, and the locker room. I really, really, like, you just, you can't replicate, you can't get back, showing up to locker room every morning just to shit talk. We've got more incredible guests like the legendary Candace Parker

and college superstar AZ Fudd. I mean, seriously, y'all. The guest list is absolutely stacked for season two. And, you know, we're always going to keep you up to speed on all the news and happenings around the women's sports world as well. So make sure you listen to Good Game with Sarah Spain on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts.

Presented by Capital One, founding partner of IHeart Women's Sports. All right, Daniel, here we go. Here's the answer to the question that we posed at the beginning. The hottest things in the universe, the absolute extreme, most hot things in the universe.

Exactly. And here I think we got to give some credit, it to the scientist for coming up with names because on this podcast we're always poking fun of scientists for naming things in a silly way. I think they did a great job here because the maximum temperature in the universe, the condition of something being at

the absolute maximum temperature, they call it absolute hot, which I think is pretty cool. You mean, wait, you're saying that there is a maximum temperature in the universe. That's right. There is a maximum temperature, and it's a crazy number, and it's

kind of a hard thing to think about. Like, why would there be a maximum temperature. You might think you can give an infinite amount of energy to a particle, and that's true, right? Like you take a single particle, you can dump as much energy as you want into it. You know, there's the speed of light issue, but we're not talking just about speed. We're talking about the energy of the particle. There's no limit to how much energy you can give a particle. But now we're talking about a system of particles. We're talking about energy density. What happens when a bunch of particles have a huge amount of energy? Well, gravity, right? Gravity, remember, bends space. And it bends space when you have particles with

mass, but also it bends space when you have energy density. Gravity is not just something that responds to mass or responds to energy. So what happens if you pour too much energy into a little blob of space? Black hole. What? Yes. Black hole, right?

There's a maximum amount of energy you can have in a certain, in a volume of space. More energy than that turns into a black hole. So you can't heat something up past that. Wait, so wait, wait, wait, wait. So I mean, I would think that the maximum temperature in the possible

theoretically is when you have a box of particles and every particle in it is moving pretty much at the speed of light because you know temperature we said before is related to how fast things are moving so what if every particle was moving at close to the speed of light you're saying that's not possible or we wouldn't even

get there that's possible it's just not even that very hot because remember the speed is not the limitation right like you can get particles up to the speed of light without even having that much energy okay and not at to the speed of light, just close to the speed of light. But remember, as you dump more energy into these particles, their speed doesn't go up very much. That's why temperature is not just the speed of the

particles, it's their energy. Remember, relativity separates speed and energy. And there's no limit to how much energy you can put into an individual particle. So you have your box. You can keep pumping energy into those particles. Their speed doesn't go up very much, but their energy increases. But you keep doing it, eventually, your box turns into a black hole. Oh, at what point does it turn into a black hole? Are you ready for the number? All right. Go for it. Hit me. Here's Absolute Hot is a billion, trillion, trillion degrees Celsius. Billion, trillion, trillion degrees. Is there a name for that?

It's called Absolute Hot. Or, more technically, it's called the Plunk temperature. Oh, but wait, is it a billion, trillion, trillion degrees, or is it, you know, 2.73 or it's just a round number. Oh, no, it's not exactly a billion, trillion, trillion degrees, but the number, if you want to know, the exact value, is 1.411. 26 times 10 to the 32 Kelvin's, all right? That's like 142 million Yata Kelvin's or 142 million quadrillion degrees Kelvin. It's pretty hot. It's a lot of, a yada. It's a lot of yada.

Exactly. It's a lot of yattas. And then you might ask like, well, you know, is that possible? Like, is it ever existed in the universe? And, you know, we don't think it's happening right now. There's nowhere in the universe that's absolute hot right now. But we think that just after the Big Bang, this crazy moment when the universe was inflating,

when it expanded really, really rapidly, we think that just before that the universe was at the plunk temperature and that that's the absolute hottest moment in the history of the universe. But there's a lot of hand-waving there because we really don't understand what happened during the Big Bang and why did it cause inflation and not just all collapse into a black hole anyway.

So there's a lot of questions about that. Okay, but the main point is that there is an absolute, like if I heat something in my frying pan forever, at some point it's going to get super hot, and at some point it's just going to turn into a black hole. It can't get any hotter

or what? You cannot create a black hole on your stovetop. I'm sorry. No matter how long you cook that bacon, it'll get black, it'll turn into charcoal, not a black hole. But if you had like laser beams and all sorts of stuff and you could like pour energy into a tiny area then in principle you could create a black hole yes well how to first of all how do you know I don't have lasers in my kitchen already you're an impressive chef and you're right I shouldn't

rule anything out I issue a formal apology but I mean basically if you heat something of long enough and you put enough energy into it at some point you're saying it's going to turn into a black hole and then it can't get any hotter or what happens then we don't know what happens then right because and it turns into like quantum gravity questions and we just don't even have a theory. So we don't, I mean, we don't know what's happening inside a black hole. If you pour energy into a black hole,

we don't know what happens. Basically, it's a huge question mark. So it's sort of a breakdown of the definition of temperature. Like, stuff definitely happens. Things get crazier. The universe gets weirder. But it's not according to our definition of temperature. The number we define as temperature doesn't go up anymore.

So maybe calling it absolute hot is a little premature. right because really you just mean like we should we have called it super duper crazy hot yeah or like super duper I don't know what happens after this hot is really sort of more accurate right we should have called it Jorge's frying pan hot yeah there you go

Jorge's black bacon hot exactly okay so that's a lot and you're saying that happened at the beginning of the universe right like it so the hottest thing in the universe ever is the Big Bang? Once again, that's the answer

for everything. The hottest thing in the universe is the Big Bang, yes, as far as we know. Okay, but that happened a while ago. But if we looked at the universe now, what would you say is the hottest thing? Well, the hottest thing recently is this quirk glue and plasma we created at the large

Hadron Collider, right? That's 5.5 trillion degrees Celsius. That's hotter than we think most things in the universe. Otherwise, like the inside of a neutron star, we think is about a hundred trillion degrees Celsius, and that's probably the otherwise hottest thing in the universe, like on a day-to-day basis, because, you know, at the Large Hajon Collider, these things

exist for 10 to the minus 23 seconds, so they don't really stick around very long. But the inside of a neutron star is super hot and very stable at 100 trillion degrees Celsius. Wow. A cool and chilly 100 trillion Celsius, which is what, like 50 Fahrenheit, or how much is that? I've no concept. Something like that. Yeah, exactly. don't pack any jackets

I don't think you'll need them because you won't be alive that's right okay cool so that's the hottest thing in the universe it's the big bang ever and it's the inside of a neutron star out there possibly right now

that's right that is the hottest place in the universe right now all right well stay tuned for future episodes in our extreme physics series we'll be tackling also the brightest thing in the universe and maybe also the densest thing in the universe.

We should also tackle like the funniest thing in the universe. That's obvious. That's this podcast. Like done. Done, yeah. But speaking of funny things, I have a request for you from a listener. All right. We have a listener in New Zealand

who's a huge fan of limericks and often tells physics limericks to his class of 10 and 11-year-olds where he teaches in New Zealand. Well, I said a limerick in our podcast a few weeks ago when we were talking about tachyons and he noticed that you didn't laugh

in my limerick. So he sent me a different physics limerick to see if we could make you chuckle. All right. So here you go. You ready? All right. All right. Hit me. There was a physicist called Joe who wanted the whole world to know that those stars that we say

are far, far away are actually long, long ago. Nice. That's cute. That's pretty cool. Yeah, that's pretty cute. Thank you. I thought you were going to rhyme what to say with Jorge, I thought it was somehow related to me. No, well, let's ask our listener to send in one tailored for you. But that's from Isaac Garmei from Coromandel, New Zealand. So thanks for sending that in.

Yeah, great. And if you have any other limericks or ideas or questions for us. Maybe a banana-related limerick for Jorge, send them in to Feedback at Danielandhorpe.com. We love your emails. Great. Thanks for listening. We hope you enjoyed this. Tune in next time. You hot person, you?

If you still have a question after listening to all these explanations, please drop us a line we'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge, that's one word, or email us at Feedback at Danielandhorpe.com. 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. luggage, kids gripping their new Christmas toys. Then everything changed. There's been a bombing at the TWA terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit.

Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. If a baby is giggling in the back seat, they're probably happy. If a baby is crying in the back seat, they're probably hungry.

But if a baby is sleeping in the back seat, will you remember they're even there? When you're distracted, stressed, or not usually the one who drives them, the chances of forgetting them in the back seat are much higher. It can happen to anyone. Parked cars get hot fast and can be deadly. So get in the habit of checking the back seat when you leave. The message from NHTSA and the ad council. This is an IHeart podcast.