Daniel and Jorge Explain the UniverseHow hot can it get? Is there an upper limit to temperature?
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Leno Lanvo. 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 the coldest 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 is impossible to go extreme physics.
I feel like we should have a heavy metal guitar sound there.
Yeahs brought to 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, the hottest thing ever or possible?
Well, if there's the 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 too for the universe to handle it.
That's right. Yeah, Or maybe you know, after you pump in too much energy, like it just blows up, or it crosses a singularity or restarts the universe, it makes a glitch in the matrix or something.
Well, at some point, whenn't you hit some sort of you know, light speed, kind of maximum limit to the 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, your way too hot. You get it. You 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 Joorge. 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 ninety hours a week. That's part time schedule. I have this podcast. I'm going to have eighty nine other podcasts I also do.
I thought you were going to say that sow much editing this podcast needs to get it down to that.
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 iHeartRadio.
That's right. And in our podcast we try to take some topic of general interest, a question people ask, that's 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'd 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, wettest, craziest things in the universe.
Sorry, there's probably some skateboarders out there or some X game athletes that are like, you know, my life is pretty extreme already. Man.
They have no idea that somebody out there in the universe surfing on black holes and riding the shockwaves of supernova is doing crazy tricks that nobody could ever imagine.
Yeah, so a few weeks ago, what is the biggest thing in the universe? Then 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.
Orge, that's right. Oh no, no, no, no, not me, the person listening.
To this, right, that's right, you, our listener, you are the hottest thing.
Yeah, you look great today. Uh 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 in 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'd 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 or they freeze you or something. But sometimes in physics we create technical definitions for things like temperature because we want to understand it, 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 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 what 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 in 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 had no idea like is it a flow? Is it a liquid is in 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 was is the hottest 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 if you see Irvine, and I asked people, what's the hottest thing in the universe? And you know, here is obviously digging for compliments, but nobody said me, right, nobody said you, nobody, nobody. Nobody gave me a compliment on how I looked that day.
Hmmm, 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 people what did people say?
Right? Well, listen to their responses and you can tell it's the hottest thing in the universe. Son our Sun, like the center of it or the surface or uh say, all of it, 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 giant stars, Yeah, all right, cool in the middle of some really dense star somewhere. Okay, So you think the center of a 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 in.
The whole universe.
I don't know.
Probably like a planet somewhere, Okay, I don't know. We'll call it the.
I don't know, the center of a sun.
Cool called that, I don't forget's right.
Don't think that's right because some of the plasmas they're saying are actually hotter than the sun.
That we have here, so that can't be right.
Yeah, okay, the center, the center of the universe.
Where's the center of the universe?
Audio? Okay? The Sun? Our sun?
Cool, like at the center of it or on the surface or somewhere in the middle.
I'm we're in the middle, firl Okay, cool all right. So pretty much people said 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 needled people and was like, you know, how about the whole universe? But still people are like, okay, maybe a different sun, like another star, the 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 been operating steadly for billions of years.
Right, beautiful, you know, and it is sort of losing weight every day, isn't it.
Yeah, yeah, exactly, despite its brilliance and people, I guess generally I feel like that must be so hot that nothing could be hotter, right.
Oh, I see, So you were prodding them to think bigger, like the most people said the sun, But then you would ask him like, no, I mean like the entire universe.
Mm hmmm, Like think for a minute, like is the sun really the hottest thing? Isn't there something else? I like to think that if they were me and somebody came and asked me about it, and I'd done no thinking or no research 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 it's different or bigger or denser or nastier, you know, or faster than we could ever imagine.
You mean, if so many oppressure on the street, do you imagine that you will just say the most correct and clever, 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. I see you think that maybe there weren't thinking that there could be something hotter than the Sun.
Yeah, that seems to be what people have. 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 that our sun is the hottest. But I think maybe they were thinking, like this the 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 a 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 it's 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 and the person next to me doesn't feel hot, then it's the difference of opinion.
Yeah, and our experience of temperature. You're right, it's 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 what, 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 then your two fingers will send you two different messages. One we'll 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 your 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 it's a bit surprised. 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 is like sort of rough and handwavy. What do you mean, Well, temperature, of the way they define it, is a measure basically of how much energy is being stored in a system of particles, but that those particles have to be an 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 said, I think when 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, What 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. The 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 hotter and 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. 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 like if they're not an 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 a 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, like say you have a wait.
What about two particles? How many particles do you need to have a temperature.
That's not even well defined? Technically you need 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 hotspots and no cold spots. Everything is sort of even doubt 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 be have infinite particles.
Yeah, but you know, like a drop of water has ten the twenty three or so particles in it, or ten to the twenty one particles in it, that's a good approximation of infinity. And so yes, you 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 there's it's an equilibrium?
Right? That's right. So for people to who don't know what I mean when I say equilibrium, take for example, so you have like a bag of gas, and that gas is at like ten degrees. You have another bag of gas that's like I don't know ninety 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 ten and ninety, Well that's fifty, right. But until those washout and all the smoshes around, physicists say there is no temperature, like you just can't define it. So that's frustrating, right, because it's 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, but it's 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 temperature 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 if anything more than you know, a billion particles, it's not a big deal. It works fine. But for if you want to talk about one particle, two particles, three particles, there isn't really a definition of temperature.
And I feel like this whole episode could have just been like, hey, what is temperature? And we could have I can spend an hour talking about this.
I know that's a pretty hot rabbit hole.
Yeah it's a hot topic. But so 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, right, how fast are these particles zipping around? And it makes a lot of sensitively when you think about an object like in as solid things are colder and things they're not moving around as much, maybe they're even trapped in a lattice, and a liquid things are moving around more, which allows a liquid to flow. In a gas, things are zipping around really fast. Right, It's related to the speed. But particles can store energy in other ways. They just don't. 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 temperature is 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 he is transferred.
Right, hmmm, okay, cool, all right, So that's a that's a definition of temperature. It only took us twenty 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.
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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 nineties. 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 nineties were pretty fraught with bad ideas.
Yeah, people made some bad choices in the nineties. Yeah exactly. But no, I do remember that website. Not that I ever participated, and I didn't object it by 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 in the on Earth. What are some of the hot hottest things on earth.
Right, Well, first of all, this clarify what we're talking about. Let's do everything in celsius. Right, So for those listeners in the US, you have to get calibrated.
Remember zero twenty minutes talking about celsius versus fahrenheit.
We're not going to debate it. We're just going for celsius for the world listeners. Zero degree celsius is the temperature which water freezes, right, and one hundred degrees, of course is where water boils. And you know, somewhere in the middle is you and me, like our body is about thirty seven degrees celsius.
Right, And you can have things colder than zero celsius.
Right, that's right. Absolutely, you can get down to like negative two hundred and seventy three degrees.
That's absolute zero, right, And that's where there're the particles, the molecules. The things in your thing have no kinetic energy.
The things in your thing. Is that a doctor 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 things are doing no more wiggling, right, they're just totally at rest. There's no kinetic energy.
Yeah, no connecticugy. You have mass, you can have energy stored in the particles and atoms, but it's just not moving.
That's right, exactly. It's an absolutely zero. So that's a negative two hundred and seventy three degrees C. And then zero is ice thirty seven degrees C is the human body. And then the hottest person ever is forty six point five degrees CE. That's like the hottest anybody ever got with a fever.
Wait, that's recorded in the history books.
Yeah, exactly.
Wow, what happens for you get hotter than forty six point five?
Well, I think your brain cooks and you turn into somebody's meal, you know, Like, 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. And when has ever gotten and survived? I think it is the cod and survived exactly, yes.
And then the hottest place on earth, you know, I think there's a a tight race here because Death Valley. I gotta 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 seventy one degrees celsius, which is really smoking hot.
Hmmm. 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 and 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 composing an email right now to the gains Poker World Records to consider your frying pan to be the hottest place on Earth. No, you're right, we do create things on Earth that are hotter, but the hottest naturally occurring air temperature manate caveas just to like, how to define the hottest place on Earth?
Yeah, so it's air temperature, hottest air temperature and earth barring any sort of like standing next to wildfire.
That's right exactly. It's seventy one degree sea And you might think, well, that's pretty hot, right, but you know it gets hotter, like even on the Moon. On the Moon, the average the average daytime temperature on the Moon is one hundred and one degree se Hmmm.
I'm just nodding along to say, 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. M it's crazy, right, Well, just it would boil. It boil anyway because there's no atmosphere. Yeah, that's not surprising.
Yeah, on Earth at our regular air pressure, one hundred is when water would boil.
Yes, exactly. So you know two engred and twelve 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 one hundred and fifty one degrees celsius. Right, that's wild Yeah, that's like much hotter than the boiling point of water. That means that whatever this thing is like it really got fried. And that's of course our friend. The tartar grade. These crazy little water bears that can survive like outer space and being frozen. They're like the heartiest thing on Earth.
Right, They're tiny, little microscopic bugs.
Right, yeah, exactly, And if you've never heard of a tartar grade, you should google them. They're incredible.
Yeah, scary looking though.
I think they look friendly. I'd like to have general.
Guitar or really, if you've been a life sized tartar grade, you would have run the other way immediately.
They look like a big snuggle. I mean, look at a big pillow. I would jump onto a tartar grade and treat it like a bean bag.
So that can So that's the heart. They can serve one hundred and fifty 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 four hundred and sixty degrees celsius. And that's because Venus has such a thick cloud layer. It's basically climate change gone crazy. All the carbadox in the atmosphere means it's a huge blanket just soaks up the sun. That's why Venus is hotter than mercury, because it just holds onto the onto the Sun's energy and cooks and cooks and cooks.
Hmm.
Cool. And that's in our space, so.
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, God.
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 to like five thousand, five hundred degrees celsius.
Wow, that's 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 six thousand 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 hot. On the surface, it's five five hundred 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 you know, 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 five hundred degrees celsius.
Cool, that's right. You have to pack a jacket. Yeah, but first you 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 five thousand degrees.
Yeah, it's crazy, right, Like, how can those two things co exist 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.
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 there's not that much energy being deposited on your body. For the energy deposit in 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. But 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 the property of the distribution. Actually, So yeah, what we're looking for is the meaning of that distribution. Yeah, but you know that's the dangerous We could go down that rabbit hole the definition of temperature for another twenty minutes.
Careful, Well, I'm still confused.
I know it's tricky. It's tricky, but let's keep going. Then you come back 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 ten to fifty million degrees celsius. Right, These are crazy high numbers that are hard to even think about.
Okay, so that means that the molecules at the center of the nuclear exporsi are moving super duper duper duper fast.
Yeah, exactly, super duper duper fast. And that number fifty 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 novah, it explodes. Well, that's a similar temperature, Like it's fifty million degrees celsius in the gas that's expelled by the supernova.
Right, Wow, that's when I start 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 that's spelled out, that's spewed out, and that's a fifty 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, than our Sun, and they're hotter than nuclear nuclear bombs going off. The highest 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 and 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 number you get is one hundred million degrees celsius.
Who 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 that probably they're all spewing away from the galaxies, but there probably are currents. It's 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's it seems empty and if you went out there and like look for particles, you wouldn't find very many. But if you have a.
Physicially get bird to a crisp is what you're sad.
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 one hundred million degrees celsius. But if you got dropped there without a spacesuit, you would not get burned. You would freeze.
I see. There are a lot of hot pins out there in that space, but they if you stood there, you wouldn't. You would hardly feel them exactly. They're there and they're really hot.
Yeah, they wouldn't. You wouldn't get hit by enough of them to keep you warm, right, You would lose. You would radiate out all your heat into the pretty empty space and freeze into a block a block of ice. Right, And you wouldn't get warmed up by the one hundred million degrees celsius plasma that surrounds you because there's hardly any particles hitting hitting you.
I see, But the average speed of those few that are there is a lot there just wouldn't exactly there just wouldn't be enough to really burn you or feel them exactly.
Yeah.
Wow.
Right, So it's zoom back to Earth because it turns out that here on Earth, we've created some pretty crazy and that's not just your frying pan. But when we collide particles at the Large Hadron 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 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 Hadron Collider, we can't talk about the temperature of one particle. But sometimes in the Large Hadron 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're trying 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 quarks 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, billiseconds, and this thing they say gets to five and a half trillion degrees celsius trillion with a t trillion with the tea exactly like that's a big number.
Well, let's get into now the hottest, the absolute champion, most hot thing in the universe. But first, let's take a quick break.
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All right, Daniel, here we go. Here's the answer to the question that we post 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 to the scientists for coming up with names. Is you know on this podcast we're always poking fund of scientists been naming things in a silly way. I think that 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 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 a 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, so 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.
Right.
Gravity is not just something that responds to mass or response the 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 wait wait, So I mean I would think that the maximum of 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 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 then not add to the speed of light, just like 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 very much, but their energy increases. But you keep doing it. Eventually your box turns into a black hole.
Oh what point does it turn into a black hole?
Are you ready for the number?
All right, go for it.
There's absolute hot. Is a billion trillion trillion degrees.
Celsius, billion trillion trillion degrees? Is there a name for that?
Or it's called absolute hot, or more technically it's called the plunk temperature.
But wait, is it a billion trillion trillion degrees or is it you know, two point seventy three or four? 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 one point four to one six times ten to the thirty two kelvins. All right, that's like one hundred and forty two million year YadA kelvins or one hundred and forty two million quadrillion degrees kelvin. It's pretty hot.
It's a lot of a YadA.
It's a lot of YadA.
YadA, a lot exactly. It's a lot of YadA.
And then you might ask like, well, you know, is that possible, like that 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, like you know, this this crazy moment when the universe was inflating, right when they expanded really really rapidly. We think that just before that that the universe was at the plunk temperature and that you know, that's the absolute hottest moment in the history of the universe. Oh, but there's a lot of handwaving 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, right, there's a lot of questions about that.
Okay, so, but there is So the main point is that there is an absolute like if I take a if I heat something in my fron pine 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 and it can't get any hotter or what.
You cannot create a black hole on your stovetop or 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, 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 have ruled anything out. I issue a formal apology.
But I mean, basically, if you heat something out 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 then it turns in 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 hug each 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. Does that the number we define as temperature doesn't go up anymore?
So maybe calling it absolute hot is a little premature, right, because really.
We've called it super duper crazy hot.
Yeah, or like super duper I don't know what happens after this hot is really sorted more accurate, right.
We should have called it Jores frying pan hot.
Yeah, there you go, Horay, is black bacon hot exactly?
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 Bank? Just once again, that's the answer for everything.
The hottest thing in the universe is the Big Bank, Yes, as far as we know.
Okay, but that happened a while ago. But if we look that the universe, now, what would you say is the hottest thing.
Well, the hottest thing recently is this quark glue on plasma we create at the large Hadron collider. Right, that's five point five trillion degrees celsius. That's hotter than we think. You know, most things in the universe otherwise, like the inside of a neutron star we think is about one 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, the large hadron collider. These things exist for ten to the minus twenty three seconds, so they don't really stick around very long. But the interestiut of a neutron star is super hot and very stable at one hundred trillion degrees celsius.
Wow, a cool and chili one hundred trillion celsius, which is what like fifty fahrenheit or how much is that? I've no conse that something like that.
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 okay, So that's the hottest thing in it's the big bang ever and it's the inside of an utron 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. Yeah, but speaking of funny things, Yeah, 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 ten and eleven year olds where he teaches in New Zealand. Well, I set a limerick in our podcast a few weeks ago when we were talking about taking ons, and he noticed that you didn't laugh at my limericks. Hmmm, So he sent me a different physics limerick to see if we could make you chuck them. All right, sore you go, you ready? All right?
Right, all right?
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.
How you were going to rhyme, let's say with Jorge, I thought it was somehow related to me.
No, Well, let's ask our listener to send in one tailor for you, but that's for Isaac Garmey from CORAMANDLLN, 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 Danielandhorge dot com. We love your emails.
Great, Thanks for listening. We hope you enjoyed this tune in next time, do 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 Danielandhorge dot 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. When you pop a piece of cheese into your mouth, you're probably not thinking about the environmental impact, but the people in the dairy industry are. That's why they're working hard every day to find new ways to reduce waste, conserve natural resources, and drive down greenhouse gas emissions. House US dairy tackling greenhouse gases. Many farms use anaerobic digestors to turn the methane from manure into renewable energy that can power farms, towns, and electric cars. Visit you as Dairy dot COM's Last Sustainability to learn more.
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