May 28, 2019 • 45 mins
How hot can it get? Is there an upper limit to temperature?
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Speaker 1 (00:07):
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
(00:29):
metal guitar sound there. Yeah. This podcast 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
(00:52):
there a point where after you pump in more energy,
it just doesn't get any hotter. It's it's an incredible idea.
It's too hot to handle, or two for the universe
to be handled, that's right, Yeah, or maybe, uh, you know,
after you pumping too much energy, like it just blows
up or it crosses a singularity or restarts the universe
and makes a glitch in the matrix or something. Well,
(01:12):
at some point when you hit some sort of um,
you know lights, be kind of maximum limit to the
in universe. Yeah, I think the physics police would pull
you over and be like, what are you doing? Explained
to us how this makes any sense? Um, your your
way too, You got it. You gotta cool it down
a little bit, leave a little room for the rest
of us to be attractive. That's right. Yeah, too much
(01:36):
sizzle exactly. Hi, I'm for Hey. I'm a cartoonists and
the creator of PhD comics. I'm Daniel. I'm a particle physicist,
(01:59):
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 a part
time schedule. I have this podcast, I'm going to have
(02:19):
eighty nine other podcasts I also do. I thought you
were gonna say that's how much editing this podcast needs
to get it down to about 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 I Heart Radio.
(02:40):
That's right, and into our podcast. We try to take
some topic of general interest, a question people ask every
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 to be on the podcast, we're
doing part two in our unofficial informal series of Universal Extremes.
(03:02):
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. They are like, you know,
my life is pretty extreme already. Man. They have no
(03:22):
idea there's somebody out there in the universe surfing on
black holes and riding the shock waves of supernova is
doing crazy tricks that nobody could have ever imagine. Yeah,
so a few weeks ago we did what is the
biggest thing in the universe? Then today we are tackling
the subject of what is the hottest thing in the universe?
(03:46):
Answer you, You are the hottest thing in the universe. Ye,
that's right. No, no, no, no, no, not me the
person listening to this. Right, that's right, you, our listener,
you are the hottest thing. You look great today. Uh yeah,
I don't need any flattery, but you know, it would
be nice to um pride the audience a little bit,
that's right. Not that we're spying on you, not that
(04:07):
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'd be fun to
(04:27):
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
(04:48):
how crazy thinks and 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 doing some reading about this.
Oh wow, really, so the hottest thing in the years
is maybe the most unexpected it's unexpectedly hot. Yeah, that's right.
(05:09):
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
(05:31):
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 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, Um, so who what? Who came first? Really?
(05:54):
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 and thousands of languages for thousands
of years, that's for sure. Um. And then people were
studying heat and thinking about like, you know, what is
heat and how does it transfer between things? And I
had no idea like is it a flow? Is it
(06:14):
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 in the episode,
but fort 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
(06:37):
thought this would be interesting to see what people think
about it, and and I give them some 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, nobody.
(06:58):
Nobody gave me a compliment on how I look that day.
M 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 So you walked around and asked
people what is the hottest thing in the universe? And
generally what what did people say? Right? Well, listen to
their responses and you can tell that's the hottest thing
(07:18):
in the universe our sun, like the center of it
or the surface or say all of it. Okay, Um,
probably like one of those big the big stars that
you see on the Twitter videos where it's like they
get bigger and they get bigger, and I don't know
what they're called, scary names, super super giant stars. Yeah, alright,
(07:40):
cool in the middle of some really dense star somewhere. Okay,
so you think the center of a star is hotter
than like it's 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. Um, I don't know, probably like
a planet. Okay, No, I don't know. Um, we'll call
(08:04):
it the I don't know, the center of a son. Center.
The sounds cool, called it. I don't think that's right,
because don't think that's right, because because some of the
plasmas they're saying are actually hotter than the sun that
we have here, so that can't be right. Uh. Okay,
the center the center of the university. Where is the
son of the universe? Okay, the Sun, our son? Cool,
(08:28):
like at the center of it, or on the surface
or somewhere in the middle, somewhere in the middle from 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. I
(08:50):
was like, you know, how about the whole universe? But
still people like, okay, maybe a different sun, like another star,
hotter sun. 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 I've been operating billions of years beautiful, you know,
and it is sort of losing weight every day, isn't it. Yeah? Yeah,
(09:11):
exactly despite its brilliance, and people, I guess generally feel
like that must be so hot that any nothing could
be hotter, right. 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. Like I think for a minute,
like is the sound really the hottest thing? Isn't there
something else? Crazy? I like to think that if it
(09:33):
was me and somebody came and asked me about it,
and I've 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 it's different or bigger or denser or nastier,
you know, or faster than we could ever imagine. You mean,
(09:54):
if so many appression 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
(10:16):
think that. I see you think that maybe they weren't
thinking that there could be something harder 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. They
weren't just thinking that our sun is the hottest. But
I think maybe they were thinking like the inside of
the sun that it can't possibly get any hotter than that. Yeah,
(10:39):
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 gonna 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 in the side that thing,
(11:00):
Like what really is temperature? Like, let me ask you, Jorge,
how would you define temperature? How would I define um?
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,
(11:22):
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 that'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 cold earth than I am right.
We don't have an absolute sense of temperature. You can
(11:44):
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 when 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,
(12:08):
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 change is 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
(12:30):
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,
but it's not something that exactly nail down. Like you
can define temperature for an infinite number of particles that
(12:51):
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 hand wavy. What do you mean, Well, temperature,
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. I mean,
you can't like have hot spots and cold spots and
(13:12):
needs to have all washed down, all the all the
edges and unevenness needs to have smoothed out. Because temperature,
in the physics point of view, is the description of
a distribution of the energy of particles in equilibrium after
everything has sort of calmed down. Um, you said a
lot of words there, Daniel said, I think what you're
trying to say, is it's it's like an average temperature.
(13:34):
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,
(13:55):
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 and cold? How can we define temperature theoretically and
(14:16):
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 of
the particles, right, and the other is the relationship between
the energy of the 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
(14:38):
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 their statistical concepts.
(15:02):
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,
(15:22):
one particle, like a single particle, doesn't have a temperature,
Like what's the temperature a single particle? It's not defined
from for a for physics temperature, right, there's like, well,
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
(15:44):
your system only has one particle, then it doesn't have
a well defined temperature. What do you mean, what if
there's this cuban space that only has one particle. You
can't say that that cube as a temperature. You can't.
That's right, And it's even weirder systum situations that you
can't say have a temperature, like say you have wait,
what about two particles? How many particles you need to
have a temperature? That's not even well defined technically, you
(16:05):
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 hot
spots and no cold spots. Everything is sort of even down, 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
(16:26):
can be have infinite particles. Yeah, but you know, like
a drop of water has tended the twenty three or
so particles and it tended to one 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
(16:49):
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 that like ten degrees. You have
another bag of gas that's like, I don't know, ninety
(17:09):
degrees or something. Now those are both in equilibrium. They
have temperatures, right, so 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 wash shout and all
of smushes around, physicists say there is no temperature, like
(17:30):
you just can't define it. So that's frustrating, right, because
it can. It's like gets in your mind, 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
(17:53):
an example of something which physics says is super duper hot.
It has a huge high temperature value. But if we
drop doing it, you would freeze. Hm. 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
(18:16):
anything more than you know, a billion particles, it's not
a big deal. It works fine, um, 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 the whole this whole episode could have just been like, hey,
what is temperature? And we could I could spend an
hour talking about this. I know that's a pretty hot
rabbit hole. Yeah, it's a hot topic. But um so,
(18:40):
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
dipping 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, and
a liquid things are moving around more, which allows a
(19:00):
liquid to flow. In the gas, things are zipping around
really fast. Right, it's related to the speed. But particles
can store energy in other ways. It 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, etcetera. 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
(19:21):
great one, okay, Yeah, And it makes perfect and tutive 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
(19:44):
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 that's a definition of temperature. It only
took us twenty minutes to get here. I know these
things sometimes are surprisingly subtle. Yeah, but 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
(20:06):
take a quick break. 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
(20:28):
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 frog with 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 objective by anybody in the internet. But I did
(20:51):
hear about that website from people. Oh I see, you
only heard about it, got it absolutely? All right, Well,
let's let's start with that in in on Earth. What
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 US,
you have to get calibrated. Remember zero twenty minutes talking
about celsius versus fahrenheits. We're not going to debate it.
(21:14):
We're just going for celsius um for the for the
world listeners, um. Zero degrees celsius is the temperature at
which water freezes, right, and a 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
(21:36):
get down to like negative two hundred and seventy three degrees.
That's absolute zero, right, And that's where they're the particles
of molecules, the things in your thing have no kinetic energy.
The things in your thing? Is that a Dr Seu's
book about physics? The things in your things, the universal
things in your universe. Oh, the things that will wiggle
(21:58):
in your things. Um, exactly. Absolute zero is when things
are doing no more wiggling, right, They're just to rest.
There's no kinnetic energy. Yeah, no, Connecticut, you have masks.
You can have energy stored in the particles and atoms,
but it's just not moving. That's right, exactly, it's an
absolute zero. So that's a negative three degrees c. And
then zero is ice seven degree C is the human body.
(22:21):
And then the hottest person ever is point five degree c.
That's like the hottest anybody ever got? Um with a fever? Wait,
that's recorded in the history books. Yeah, exactly what happens
when 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
(22:42):
survive much more than that. But this is not a
biology podcast or a cannibalism podcast, right, um soum. So
that's the hottest fever and one has ever gotten and survived.
I think is the and survived exactly, yes, um, And
then the hottest place on Earth. You know, I think
there's a a tight race here because Death Valley. I
(23:02):
gotta give my props to Southern Califorment and 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 degree 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
(23:23):
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 stoves, that's the hottest place you would feel
on Earth. Yeah. No, I think I'm composing an email
(23:45):
right now to the Guinstpoker 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 in the
caveats just to like, how did defy in the hottest
place on Earth. So it's air temperature, hottest air temperature
on Earth, barring any sort of like standing next to wildfire.
(24:07):
That's right exactly. UM is seventy one degreased C. And
you might think, well, that's pretty hot, right, but you
know it gets hotter, like even on the Moon. The
on the Moon, the the average the average daytime temperature
on the Moon is a hundred and one degreas C.
I'm just nodding along because that I'm used to fahrenheit.
So I'm gonna take your word that that's pretty hot.
(24:29):
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 just it would boil. Um, it would boil anyway
because there's no atmosphere. Yeah, that's not surprising. Um on
Earth at our regular air pressure, a hundred is when
water would boil, yes, exactly. So you know two degrees
(24:52):
fahrenheit that's a pretty hot temperature for the surface of
the Moon. Um. And then here's this is one of
my favorite ones. The hottest temperature ever revived by a
living thing. That's a hundred and fifty one degrees celsius, right,
that's why. Yeah, that's like much hotter than the boiling
point of water. That means that whatever this thing is like,
(25:12):
it's uh, 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 hardiest thing on Earth right through tiny little
microscopic bugs. Right, yeah, exactly, And you should 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.
(25:34):
I'd like to have dinner with the targe. Really, have
you been a life size Tartar grade, you would have
run the other way immediately. They look like a big snuggle.
I mean they're look at the big pillow. I would
jump onto a Tartar grade and treat like a bean bag,
all right, So that that can to that's the heart
that they can survive a hundred and fifty degrees celsis. Yeah,
that's the hottest temperature ever survived by a living thing.
(25:55):
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. Um.
But then leaving the surface of the Earth, the hottest
spot of the hottest naturally occurring spot in the Solar
System is the surface of Venus, which is four hundred
and sixty degrees celsius. And that's because Venus is such
(26:17):
a thick cloud layer. It's basically basically climate change gone crazy.
All the carbodox 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 onto the
onto the Sun's energy and cooks and cooks and cooks
cool And that's in our space. So um, well it's
(26:37):
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
the thermometer in the surface of Venus, that's what you
ad 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,
(26:58):
five hundred degrees celsius. Wow, that's a 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 the 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 um celsius. So
(27:19):
that's hotter than the surface of the Sun. So the
molecules at the center of the Earth are moving faster
than the molecules in the 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,
(27:40):
hotter than the surface. Yeah, it's weird hot. On the surface,
it's five thousand, 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, you know, I don't even think it's that
well understood. Like the dynamics of the Sun, how that
all works is something that we're still really studying. In fact,
there's ending a probe right now to go like orbit
(28:02):
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 uh, 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
(28:23):
degrees celsius. That's right, you have to pack a jacket.
But first you have to get through the Sun's atmosphere
in 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?
And it doesn't really make sense. But I think a
lot of that is because the Sun is expelling all
(28:44):
this energy, right, and so the the gas the correct
in the corona gets heated up. But also I think
there's there's something going on here about 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
(29:05):
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
(29:27):
cook you because it'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 both. Wait
when you say, temperature is the average kinetic energy. What
do you take the average of like particles? Do you
You know, you take the total energy and you divide
(29:48):
by the number of particles. What does it mean to
take the average? Yeah, it's act the 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 we could go down that rabbit hole the definition
of temperature for another twenty minutes. Be careful. Well, I'm
still confused. I know it's tricky. It's tricky. Um, but
(30:13):
let's keep going. Um. 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. Um, when we still used 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,
(30:36):
so that means that the molecules at the center of
the nuclear exupportion 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, no, it explodes. Well, that's a
(30:56):
similar temperature. Like it's fifty million degrees celsius um in
the gas that's expelled by the supernova. Right, that's when
I start collapses. Right, That's right, the star collapses and
then explodes um. 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 a spewed out and that's a fifty million degrees celsius. Okay, cool.
(31:20):
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
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
(31:40):
of gas in the mixed stars, etcetera. 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. That'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
(32:03):
really really hot, Like those particles are really moving and
the temperature never number you get is a hundred million
degrees celsius. 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,
(32:24):
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 of huge clouds
of gas that's spewing stuff out. So I think they're
getting the sources the galaxies that 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
(32:45):
really complicated. 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, you would get burned to a crisp.
You would not get burned to a crisp because there
are hardly any particles out there, And you can ask
(33:06):
a physicists like, hey, what's the temperature out here, and
they'd be like, m, 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 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, they wouldn't. You wouldn't get hit by
(33:28):
enough of them to keep you warm, right, you would lose.
You would radiate 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 hundred million
degrees celsius plasma that surrounds you because it's hardly any
part of hitting you, all right, see, but the average
speed of those few that are there is a lot
(33:50):
there wouldn't exactly 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 hot stuff. 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,
(34:13):
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, well, 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
(34:35):
big stuff like the nucleus of a gold atom or
lid atom, and we smash those together, and the reason
is that they're trying to break up the matter and
create this this condition that they think existed in the
early universe. It's called the cork 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
(34:58):
particles together so you know, lead and uh 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
of seconds, and this thing they say, he gets to
five and a half trillion degrees celsius trillion with the
(35:19):
T trillion with the T 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. All right, Daniel, here we go. Here's the
(35:46):
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 scientist for
coming up with names. Is you know, on this podcast
we're always poking fund of scientists for naming things in
a silly way. I think they did a great job here.
Because the maximum the temperature in the universe, the condition
(36:08):
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
(36:31):
energy to a particle, and that's true, right, Like you
take a single particle, you can dumb as much energy
as you want into it. You know, there's a state
of light issue. But we're not talking just about speed.
We're talking about the energy of the particles. 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?
(36:54):
Remember bends space, and it bends space when you have
particles with mass, but also it bends space and you
have energy density. Alright, gravity is not just something that
responds to mass, a response 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
(37:14):
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 to wait wait wait wait wait wait,
So the 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
(37:35):
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 speed
is not the limitation, right, Like, you can get particles
up to the speed of light without even having that
(37:55):
much energy. Okay, and not bad 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 separate speed and energy, and there's no limit to
how much energy you can put into an individual particles.
You have your box. You can keep pumping energy into
(38:16):
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? For here'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
(38:39):
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 one six times ten to the
thirty two kelvin. All right, that's like a hundred and
(39:02):
forty two million yadda kelvin's or a hundred and forty
two million quadrillion degrees kelvin. It's pretty hot. It's a
lot of YadA, it's a it's a lot of And
then you might ask like, well, you know, is that possible,
like that ever existed in the universe, And you know,
(39:23):
we don't think it's happening right now. There's nowhere in
the universe that's absolute hot right now. Um, 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 uh, you know, that's the absolute hottest moment
(39:46):
in the history of the universe. 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,
there's a lot of questions about that, Okay, there is.
So the main point is that there is an absolute
like if I take a if I heat something in
my frying pine forever. At some point it's gonna get
(40:07):
super hot, and at some point it's it's just gonna
turn into a black hole and it can't get any
harder or what. You cannot create a black hole on
your stovetop working, 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
(40:30):
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 have ruled anything out. I issue formal apology. Um,
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 harder or what happens.
(40:51):
Then we don't know what happens then, right, because then
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 poor energy into a black hole, we don't know
what happens. Um. 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 crazy, or the universe
(41:11):
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 it really you've called it super
duper crazy hot, yeah, or like super duper I don't
know what happens after this hot is really sort of
(41:33):
more accurate, right, But we should have called it Jog's
frying pan hot. Yeah, there you go. Jore is black
bacon hot exactly exactly. Okay, So that's a lot um
And you're saying that happened at the beginning of the universe, right,
like it. So the hottest thing in the universe ever
(41:53):
is the Big Band. Just 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 what would you say is the
hottest thing, Well, the hottest thing recently is this cork
glue on plasma we create the at the large hage
On collider. Right, that's five point five trillion degrees celsius.
(42:15):
That's hotter than we think, you know, most things in
the universe. Um, 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,
the large Hagron collider, these things exist for ten to
the might is twenty three seconds, so they don't really
stick around very long. But the intside of a neutron
(42:36):
star is super hot and very stable at a hundred
trillion degrees celsius. Wow, a cool and chili hundred trillion celsius,
which is what like fifty fahrenheit or how much is that?
I have no concept something like that, something like that. Yeah, exactly. Um,
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,
(43:03):
so that's the hottest thing in the universe. It's the
big Bang ever and it's the inside of an intrance
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
will be tackling also the brightest thing in the universe
(43:24):
and maybe also the densest thing in the universe. We
should also tackle like the funniest thing in the universe.
That's obviously that's this podcast like done. Yeah, but speaking
of funny things, yea, 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
(43:47):
year olds where he teaches in New Zealand. Well, I
said a limerick in our podcast a few weeks ago.
We were talking about tacking on and uh, he noticed
that you didn't laugh at my limerick, so he sent
me a different physics rick to see if we can
make you chuckle. All right, So here you go, you ready,
right right, all right? Hit me. There was a physicist
called Joe who wanted the whole world to know that
(44:10):
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 Ryan. Let's say with Jorge,
I thought it was somehow related to me. No. Um, Well,
let's ask our our listener to send in one tailor
for you. But that's for Isaac Garmet from Coromandel, New Zealand.
(44:34):
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
two feedback at Daniel and Jorge dot com. We love
your emails. Great, thanks for listening and we hope you
enjoyed this. Tune in next time the hot person you. Yeah,
(45:02):
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 Daniel and Jorge dot com.
Thanks for listening, and remember that Daniel and Jorge explain,
the universe is a production of I heart Radio. For
(45:24):
more podcast from My heart Radio, visit the I heart
Radio app, Apple Podcasts, or wherever you listen to your
favorite shows.
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
(00:29):
metal guitar sound there. Yeah. This podcast 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
(00:52):
there a point where after you pump in more energy,
it just doesn't get any hotter. It's it's an incredible idea.
It's too hot to handle, or two for the universe
to be handled, that's right, Yeah, or maybe, uh, you know,
after you pumping too much energy, like it just blows
up or it crosses a singularity or restarts the universe
and makes a glitch in the matrix or something. Well,
(01:12):
at some point when you hit some sort of um,
you know lights, be kind of maximum limit to the
in universe. Yeah, I think the physics police would pull
you over and be like, what are you doing? Explained
to us how this makes any sense? Um, your your
way too, You got it. You gotta cool it down
a little bit, leave a little room for the rest
of us to be attractive. That's right. Yeah, too much
(01:36):
sizzle exactly. Hi, I'm for Hey. I'm a cartoonists and
the creator of PhD comics. I'm Daniel. I'm a particle physicist,
(01:59):
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 a part
time schedule. I have this podcast, I'm going to have
(02:19):
eighty nine other podcasts I also do. I thought you
were gonna say that's how much editing this podcast needs
to get it down to about 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 I Heart Radio.
(02:40):
That's right, and into our podcast. We try to take
some topic of general interest, a question people ask every
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 to be on the podcast, we're
doing part two in our unofficial informal series of Universal Extremes.
(03:02):
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. They are like, you know,
my life is pretty extreme already. Man. They have no
(03:22):
idea there's somebody out there in the universe surfing on
black holes and riding the shock waves of supernova is
doing crazy tricks that nobody could have ever imagine. Yeah,
so a few weeks ago we did what is the
biggest thing in the universe? Then today we are tackling
the subject of what is the hottest thing in the universe?
(03:46):
Answer you, You are the hottest thing in the universe. Ye,
that's right. No, no, no, no, no, not me the
person listening to this. Right, that's right, you, our listener,
you are the hottest thing. You look great today. Uh yeah,
I don't need any flattery, but you know, it would
be nice to um pride the audience a little bit,
that's right. Not that we're spying on you, not that
(04:07):
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'd be fun to
(04:27):
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
(04:48):
how crazy thinks and 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 doing some reading about this.
Oh wow, really, so the hottest thing in the years
is maybe the most unexpected it's unexpectedly hot. Yeah, that's right.
(05:09):
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
(05:31):
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 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, Um, so who what? Who came first? Really?
(05:54):
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 and thousands of languages for thousands
of years, that's for sure. Um. And then people were
studying heat and thinking about like, you know, what is
heat and how does it transfer between things? And I
had no idea like is it a flow? Is it
(06:14):
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 in the episode,
but fort 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
(06:37):
thought this would be interesting to see what people think
about it, and and I give them some 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, nobody.
(06:58):
Nobody gave me a compliment on how I look that day.
M 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 So you walked around and asked
people what is the hottest thing in the universe? And
generally what what did people say? Right? Well, listen to
their responses and you can tell that's the hottest thing
(07:18):
in the universe our sun, like the center of it
or the surface or say all of it. Okay, Um,
probably like one of those big the big stars that
you see on the Twitter videos where it's like they
get bigger and they get bigger, and I don't know
what they're called, scary names, super super giant stars. Yeah, alright,
(07:40):
cool in the middle of some really dense star somewhere. Okay,
so you think the center of a star is hotter
than like it's 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. Um, I don't know, probably like
a planet. Okay, No, I don't know. Um, we'll call
(08:04):
it the I don't know, the center of a son. Center.
The sounds cool, called it. I don't think that's right,
because don't think that's right, because because some of the
plasmas they're saying are actually hotter than the sun that
we have here, so that can't be right. Uh. Okay,
the center the center of the university. Where is the
son of the universe? Okay, the Sun, our son? Cool,
(08:28):
like at the center of it, or on the surface
or somewhere in the middle, somewhere in the middle from 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. I
(08:50):
was like, you know, how about the whole universe? But
still people like, okay, maybe a different sun, like another star,
hotter sun. 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 I've been operating billions of years beautiful, you know,
and it is sort of losing weight every day, isn't it. Yeah? Yeah,
(09:11):
exactly despite its brilliance, and people, I guess generally feel
like that must be so hot that any nothing could
be hotter, right. 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. Like I think for a minute,
like is the sound really the hottest thing? Isn't there
something else? Crazy? I like to think that if it
(09:33):
was me and somebody came and asked me about it,
and I've 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 it's different or bigger or denser or nastier,
you know, or faster than we could ever imagine. You mean,
(09:54):
if so many appression 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
(10:16):
think that. I see you think that maybe they weren't
thinking that there could be something harder 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. They
weren't just thinking that our sun is the hottest. But
I think maybe they were thinking like the inside of
the sun that it can't possibly get any hotter than that. Yeah,
(10:39):
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 gonna 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 in the side that thing,
(11:00):
Like what really is temperature? Like, let me ask you, Jorge,
how would you define temperature? How would I define um?
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,
(11:22):
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 that'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 cold earth than I am right.
We don't have an absolute sense of temperature. You can
(11:44):
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 when 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,
(12:08):
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 change is 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
(12:30):
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,
but it's not something that exactly nail down. Like you
can define temperature for an infinite number of particles that
(12:51):
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 hand wavy. What do you mean, Well, temperature,
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. I mean,
you can't like have hot spots and cold spots and
(13:12):
needs to have all washed down, all the all the
edges and unevenness needs to have smoothed out. Because temperature,
in the physics point of view, is the description of
a distribution of the energy of particles in equilibrium after
everything has sort of calmed down. Um, you said a
lot of words there, Daniel said, I think what you're
trying to say, is it's it's like an average temperature.
(13:34):
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,
(13:55):
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 and cold? How can we define temperature theoretically and
(14:16):
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 of
the particles, right, and the other is the relationship between
the energy of the 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
(14:38):
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 their statistical concepts.
(15:02):
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,
(15:22):
one particle, like a single particle, doesn't have a temperature,
Like what's the temperature a single particle? It's not defined
from for a for physics temperature, right, there's like, well,
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
(15:44):
your system only has one particle, then it doesn't have
a well defined temperature. What do you mean, what if
there's this cuban space that only has one particle. You
can't say that that cube as a temperature. You can't.
That's right, And it's even weirder systum situations that you
can't say have a temperature, like say you have wait,
what about two particles? How many particles you need to
have a temperature? That's not even well defined technically, you
(16:05):
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 hot
spots and no cold spots. Everything is sort of even down, 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
(16:26):
can be have infinite particles. Yeah, but you know, like
a drop of water has tended the twenty three or
so particles and it tended to one 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
(16:49):
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 that like ten degrees. You have
another bag of gas that's like, I don't know, ninety
(17:09):
degrees or something. Now those are both in equilibrium. They
have temperatures, right, so 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 wash shout and all
of smushes around, physicists say there is no temperature, like
(17:30):
you just can't define it. So that's frustrating, right, because
it can. It's like gets in your mind, 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
(17:53):
an example of something which physics says is super duper hot.
It has a huge high temperature value. But if we
drop doing it, you would freeze. Hm. 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
(18:16):
anything more than you know, a billion particles, it's not
a big deal. It works fine, um, 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 the whole this whole episode could have just been like, hey,
what is temperature? And we could I could spend an
hour talking about this. I know that's a pretty hot
rabbit hole. Yeah, it's a hot topic. But um so,
(18:40):
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
dipping 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, and
a liquid things are moving around more, which allows a
(19:00):
liquid to flow. In the gas, things are zipping around
really fast. Right, it's related to the speed. But particles
can store energy in other ways. It 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, etcetera. 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
(19:21):
great one, okay, Yeah, And it makes perfect and tutive 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
(19:44):
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 that's a definition of temperature. It only
took us twenty minutes to get here. I know these
things sometimes are surprisingly subtle. Yeah, but 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
(20:06):
take a quick break. 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
(20:28):
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 frog with 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 objective by anybody in the internet. But I did
(20:51):
hear about that website from people. Oh I see, you
only heard about it, got it absolutely? All right, Well,
let's let's start with that in in on Earth. What
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 US,
you have to get calibrated. Remember zero twenty minutes talking
about celsius versus fahrenheits. We're not going to debate it.
(21:14):
We're just going for celsius um for the for the
world listeners, um. Zero degrees celsius is the temperature at
which water freezes, right, and a 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
(21:36):
get down to like negative two hundred and seventy three degrees.
That's absolute zero, right, And that's where they're the particles
of molecules, the things in your thing have no kinetic energy.
The things in your thing? Is that a Dr Seu's
book about physics? The things in your things, the universal
things in your universe. Oh, the things that will wiggle
(21:58):
in your things. Um, exactly. Absolute zero is when things
are doing no more wiggling, right, They're just to rest.
There's no kinnetic energy. Yeah, no, Connecticut, you have masks.
You can have energy stored in the particles and atoms,
but it's just not moving. That's right, exactly, it's an
absolute zero. So that's a negative three degrees c. And
then zero is ice seven degree C is the human body.
(22:21):
And then the hottest person ever is point five degree c.
That's like the hottest anybody ever got? Um with a fever? Wait,
that's recorded in the history books. Yeah, exactly what happens
when 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
(22:42):
survive much more than that. But this is not a
biology podcast or a cannibalism podcast, right, um soum. So
that's the hottest fever and one has ever gotten and survived.
I think is the and survived exactly, yes, um, And
then the hottest place on Earth. You know, I think
there's a a tight race here because Death Valley. I
(23:02):
gotta give my props to Southern Califorment and 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 degree 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
(23:23):
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 stoves, that's the hottest place you would feel
on Earth. Yeah. No, I think I'm composing an email
(23:45):
right now to the Guinstpoker 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 in the
caveats just to like, how did defy in the hottest
place on Earth. So it's air temperature, hottest air temperature
on Earth, barring any sort of like standing next to wildfire.
(24:07):
That's right exactly. UM is seventy one degreased C. And
you might think, well, that's pretty hot, right, but you
know it gets hotter, like even on the Moon. The
on the Moon, the the average the average daytime temperature
on the Moon is a hundred and one degreas C.
I'm just nodding along because that I'm used to fahrenheit.
So I'm gonna take your word that that's pretty hot.
(24:29):
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 just it would boil. Um, it would boil anyway
because there's no atmosphere. Yeah, that's not surprising. Um on
Earth at our regular air pressure, a hundred is when
water would boil, yes, exactly. So you know two degrees
(24:52):
fahrenheit that's a pretty hot temperature for the surface of
the Moon. Um. And then here's this is one of
my favorite ones. The hottest temperature ever revived by a
living thing. That's a hundred and fifty one degrees celsius, right,
that's why. Yeah, that's like much hotter than the boiling
point of water. That means that whatever this thing is like,
(25:12):
it's uh, 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 hardiest thing on Earth right through tiny little
microscopic bugs. Right, yeah, exactly, And you should 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.
(25:34):
I'd like to have dinner with the targe. Really, have
you been a life size Tartar grade, you would have
run the other way immediately. They look like a big snuggle.
I mean they're look at the big pillow. I would
jump onto a Tartar grade and treat like a bean bag,
all right, So that that can to that's the heart
that they can survive a hundred and fifty degrees celsis. Yeah,
that's the hottest temperature ever survived by a living thing.
(25:55):
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. Um.
But then leaving the surface of the Earth, the hottest
spot of the hottest naturally occurring spot in the Solar
System is the surface of Venus, which is four hundred
and sixty degrees celsius. And that's because Venus is such
(26:17):
a thick cloud layer. It's basically basically climate change gone crazy.
All the carbodox 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 onto the
onto the Sun's energy and cooks and cooks and cooks
cool And that's in our space. So um, well it's
(26:37):
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
the thermometer in the surface of Venus, that's what you
ad 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,
(26:58):
five hundred degrees celsius. Wow, that's a 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 the 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 um celsius. So
(27:19):
that's hotter than the surface of the Sun. So the
molecules at the center of the Earth are moving faster
than the molecules in the 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,
(27:40):
hotter than the surface. Yeah, it's weird hot. On the surface,
it's five thousand, 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, you know, I don't even think it's that
well understood. Like the dynamics of the Sun, how that
all works is something that we're still really studying. In fact,
there's ending a probe right now to go like orbit
(28:02):
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 uh, 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
(28:23):
degrees celsius. That's right, you have to pack a jacket.
But first you have to get through the Sun's atmosphere
in 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?
And it doesn't really make sense. But I think a
lot of that is because the Sun is expelling all
(28:44):
this energy, right, and so the the gas the correct
in the corona gets heated up. But also I think
there's there's something going on here about 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
(29:05):
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
(29:27):
cook you because it'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 both. Wait
when you say, temperature is the average kinetic energy. What
do you take the average of like particles? Do you
You know, you take the total energy and you divide
(29:48):
by the number of particles. What does it mean to
take the average? Yeah, it's act the 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 we could go down that rabbit hole the definition
of temperature for another twenty minutes. Be careful. Well, I'm
still confused. I know it's tricky. It's tricky. Um, but
(30:13):
let's keep going. Um. 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. Um, when we still used 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,
(30:36):
so that means that the molecules at the center of
the nuclear exupportion 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, no, it explodes. Well, that's a
(30:56):
similar temperature. Like it's fifty million degrees celsius um in
the gas that's expelled by the supernova. Right, that's when
I start collapses. Right, That's right, the star collapses and
then explodes um. 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 a spewed out and that's a fifty million degrees celsius. Okay, cool.
(31:20):
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
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
(31:40):
of gas in the mixed stars, etcetera. 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. That'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
(32:03):
really really hot, Like those particles are really moving and
the temperature never number you get is a hundred million
degrees celsius. 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,
(32:24):
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 of huge clouds
of gas that's spewing stuff out. So I think they're
getting the sources the galaxies that 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
(32:45):
really complicated. 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, you would get burned to a crisp.
You would not get burned to a crisp because there
are hardly any particles out there, And you can ask
(33:06):
a physicists like, hey, what's the temperature out here, and
they'd be like, m, 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 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, they wouldn't. You wouldn't get hit by
(33:28):
enough of them to keep you warm, right, you would lose.
You would radiate 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 hundred million
degrees celsius plasma that surrounds you because it's hardly any
part of hitting you, all right, see, but the average
speed of those few that are there is a lot
(33:50):
there wouldn't exactly 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 hot stuff. 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,
(34:13):
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, well, 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
(34:35):
big stuff like the nucleus of a gold atom or
lid atom, and we smash those together, and the reason
is that they're trying to break up the matter and
create this this condition that they think existed in the
early universe. It's called the cork 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
(34:58):
particles together so you know, lead and uh 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
of seconds, and this thing they say, he gets to
five and a half trillion degrees celsius trillion with the
(35:19):
T trillion with the T 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. All right, Daniel, here we go. Here's the
(35:46):
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 scientist for
coming up with names. Is you know, on this podcast
we're always poking fund of scientists for naming things in
a silly way. I think they did a great job here.
Because the maximum the temperature in the universe, the condition
(36:08):
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
(36:31):
energy to a particle, and that's true, right, Like you
take a single particle, you can dumb as much energy
as you want into it. You know, there's a state
of light issue. But we're not talking just about speed.
We're talking about the energy of the particles. 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?
(36:54):
Remember bends space, and it bends space when you have
particles with mass, but also it bends space and you
have energy density. Alright, gravity is not just something that
responds to mass, a response 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
(37:14):
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 to wait wait wait wait wait wait,
So the 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
(37:35):
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 speed
is not the limitation, right, Like, you can get particles
up to the speed of light without even having that
(37:55):
much energy. Okay, and not bad 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 separate speed and energy, and there's no limit to
how much energy you can put into an individual particles.
You have your box. You can keep pumping energy into
(38:16):
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? For here'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
(38:39):
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 one six times ten to the
thirty two kelvin. All right, that's like a hundred and
(39:02):
forty two million yadda kelvin's or a hundred and forty
two million quadrillion degrees kelvin. It's pretty hot. It's a
lot of YadA, it's a it's a lot of And
then you might ask like, well, you know, is that possible,
like that ever existed in the universe, And you know,
(39:23):
we don't think it's happening right now. There's nowhere in
the universe that's absolute hot right now. Um, 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 uh, you know, that's the absolute hottest moment
(39:46):
in the history of the universe. 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,
there's a lot of questions about that, Okay, there is.
So the main point is that there is an absolute
like if I take a if I heat something in
my frying pine forever. At some point it's gonna get
(40:07):
super hot, and at some point it's it's just gonna
turn into a black hole and it can't get any
harder or what. You cannot create a black hole on
your stovetop working, 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
(40:30):
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 have ruled anything out. I issue formal apology. Um,
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 harder or what happens.
(40:51):
Then we don't know what happens then, right, because then
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 poor energy into a black hole, we don't know
what happens. Um. 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 crazy, or the universe
(41:11):
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 it really you've called it super
duper crazy hot, yeah, or like super duper I don't
know what happens after this hot is really sort of
(41:33):
more accurate, right, But we should have called it Jog's
frying pan hot. Yeah, there you go. Jore is black
bacon hot exactly exactly. Okay, So that's a lot um
And you're saying that happened at the beginning of the universe, right,
like it. So the hottest thing in the universe ever
(41:53):
is the Big Band. Just 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 what would you say is the
hottest thing, Well, the hottest thing recently is this cork
glue on plasma we create the at the large hage
On collider. Right, that's five point five trillion degrees celsius.
(42:15):
That's hotter than we think, you know, most things in
the universe. Um, 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,
the large Hagron collider, these things exist for ten to
the might is twenty three seconds, so they don't really
stick around very long. But the intside of a neutron
(42:36):
star is super hot and very stable at a hundred
trillion degrees celsius. Wow, a cool and chili hundred trillion celsius,
which is what like fifty fahrenheit or how much is that?
I have no concept something like that, something like that. Yeah, exactly. Um,
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,
(43:03):
so that's the hottest thing in the universe. It's the
big Bang ever and it's the inside of an intrance
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
will be tackling also the brightest thing in the universe
(43:24):
and maybe also the densest thing in the universe. We
should also tackle like the funniest thing in the universe.
That's obviously that's this podcast like done. Yeah, but speaking
of funny things, yea, 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
(43:47):
year olds where he teaches in New Zealand. Well, I
said a limerick in our podcast a few weeks ago.
We were talking about tacking on and uh, he noticed
that you didn't laugh at my limerick, so he sent
me a different physics rick to see if we can
make you chuckle. All right, So here you go, you ready,
right right, all right? Hit me. There was a physicist
called Joe who wanted the whole world to know that
(44:10):
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 Ryan. Let's say with Jorge,
I thought it was somehow related to me. No. Um, Well,
let's ask our our listener to send in one tailor
for you. But that's for Isaac Garmet from Coromandel, New Zealand.
(44:34):
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
two feedback at Daniel and Jorge dot com. We love
your emails. Great, thanks for listening and we hope you
enjoyed this. Tune in next time the hot person you. Yeah,
(45:02):
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 Daniel and Jorge dot com.
Thanks for listening, and remember that Daniel and Jorge explain,
the universe is a production of I heart Radio. For
(45:24):
more podcast from My heart Radio, visit the I heart
Radio app, Apple Podcasts, or wherever you listen to your
favorite shows.
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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