August 27, 2019 • 35 mins
Join Daniel and Jorge to find out the secrets of the universe.
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Episode Transcript
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Speaker 1 (00:08):
Hey, hey, it's that time again. What are we talking
about today? It's time to talk about particle names, my
favorite subject. Hey, don't blame me. There are a lot
of particles out there. All right, let's do it, Daniel. Well,
today's game is I'm gonna give you a word and
you have to guess whether it's the name of a
fundamental particle or the name of a character in the Transformers.
(00:32):
All right, I'm ready to me alright, first one, Megatron,
that one down to give me. That's definitely a Transformer.
All right, that was the warm up. How about Galvatron.
I'm gonna go with particle alright, Computron, I'm gonna go
with the Transformer or eighties computer company? Alright. Last one
(00:52):
is tripp to con That sounds more like a convention
for pleasant nerds. Hey, I want to go to that.
That sounds awesome. Yeah, alright, Which ones are particles and
which ones are Transformers? All right? It was a bit
of a trick question. They were all names of Transformers.
What I had to do a bit of deep research.
(01:14):
But those are actual Transformer character names. Oh man, you
got me, all right, but you have to promise me
if you ever discover a particle Daniel at the large
Headron collider. You have to name it Mega Tromp done.
(01:45):
Hi am Jorge. I'm a cartoonists and the creator of
PhD comics. Hi I'm Daniel. I'm a particle physicist, a
closet transformer geek, and definitely a nerd. And Welcome to
our podcast. Daniel and Jorge explain eighties toy franchises. No,
I mean Daniel and Orge explained the universe a production
of My Heart Radio. I Heart Radio is going to
(02:05):
get sued now by mattel or whoever puts out the transformers.
This is the first domino, isn't it the beginning of
the downfall of the podcast? Um? But welcome to our podcast,
in which we take crazy, amazing things that blow your
mind and try to relate them to silly, fun easily
understandable things like robots that turn into cars or airplanes
or you know, dinosaurs. Television transforms are very versatile. I
(02:28):
never understood the dinosaur thing, Like, you're already a killer robot.
What's the advantage of transforming into a dinosaur? Like? Seriously,
I mean, think about this robot versus dinosaur. Who wins
robot every time, right, I think they're just trying to
blend in with the other dinosaurs. All these are prehistoric transformers,
robots in disguise. So if transformers had come to Earth
(02:48):
before the dinosaurs, wouldy have transformed into like insects and
like trilobytes and stuff like that. They did, they there's
this transformer for everything. But anyways, welcome to a podcast
in which we talk about all the things in universe,
the big ones, the small ones, the ones that maybe
don't even exist. That's right, and we love delving into
these theoretical hypothetical topics, and so today we're going to
(03:10):
talk about a very interesting concept, right Daniel, which is
something that maybe in your everyday life, affecting you on
a daily, every second of your life basis um, but
which physicists don't even know if it exists or not.
That's right. This relates to something you experience every day,
but physics still doesn't really understand that kind of thing,
(03:31):
which in two hundred years people will look back and say, man,
I wish I had had those ideas. I totally would
have gotten the Nobel Prize. The puzzle was right there
in front of them and it's something that I think
you've told me this before that if it exists, it
may totally upend all of our theories about physics, right,
that's right. One of the challenges with this kind of
idea is that we don't even really know how to
(03:52):
form the idea, Like the idea itself has problems, not
to mention whether or not it exists, but we can't
even really seem to get it to behave its on
the page, so to the On the podcast, we'll be
talking about the graviton. What is the graviton? Is it
a transformer for a transformer? Is it a particle? Is it?
(04:18):
And how is it pronounced? Really? Is it graviton or
is it gravyton? Or yeah? What kind of transformer would
the gravyton be? Shoot streams of hot gravy at you
or something transformed into a gravy bowl? Oh? Man, so
terrifying grav versus turkey tron, based, the based or based
(04:40):
or bot. No, but it's a funny name. And you know,
you are often a critic of physics naming, and so
you know, if the folks have done a good job
in this case, then the name should be pretty clear, right,
that's your mattress, name something in a clear way, so
not knowing anything about it, just knowing the name. What
do you imagine the A baton means the gravytan um
(05:04):
you has something to do with graves or I imagine
it has something to do with gravity, like a gravity thing.
I like how you first went for gravy, second went
for graves, and only third on the Physics podcast considered
we might be talking about gravity. So yeah, it's a
particle related to gravity right now? Yeah, exactly, and we'll
be talking exactly about what that means. And we've touched
(05:26):
on this a few times, but this is the scenario
where a particle exists theoretically and it's already been given
a name before it's discovered. If some particles we find them,
then we argue about how to name it. Right, some
particles are named before they're discovered, like we have the
idea for them, and then we go ahead and find it.
We already know what to call it, like the Higgs boson.
(05:48):
So let's say your physicist and you think of something
on the on your notepad, or you find something. Do
you think most physicists have sort of a pre name
in their minds when they're looking for these things, or
even if they're I don't think they're looking for these things.
I don't know. Um, but I haven't noticed recently there
are a lot more names being given to ideas. I
think this is, you know, young people coming up and
(06:10):
recognizing the value of branding, and so every sort of
new idea that something that comes up with has like
a slick sounding name that's associated with it so that
it sticks in people's heads. It's not just some complicated
new idea, you know, it's it's it's got some branding
to it. Cool. Um, But of course I've already thought
about the name of a particle I would discover. Oh yeah,
(06:31):
I mean my last name ends with S O N.
So it's very clearly I got to call it the
White Song. I know, you would have to call it
the whites some ton. That sounds like some complicated Icelandic person. Cool.
So today we'll be talking about what is the graviton
and does it exist? And what does it mean if
we ever actually find this particle? Right, and how would
(06:54):
we look for it and what would it mean? Yeah,
so it sounds like something either out of a Transformers
movie or some thing out of a physics textbook. But
we were wondering, as usual, how many people out there
know what a graviton is. So I walked around wherever
I was in the world, and I asked people what
they knew about the graviton. Could they explain it? Did
they have any idea? Had they heard it before? Did
(07:15):
they play with one when they were a kid. So
before you listen to these, think about it for a second.
If you were approached by a physicist at an airport
in London, what would you answer to the question what
is a graviton? Here? It's what people had to say.
I heard of it, but I don't know it. It's problem.
But you know grav with you? Yeah, okay, I heard
(07:38):
about gravity, but I don't I've ever heard about a
material like graviton. No. Gravitons, Yes, they're the theoretical particle
that is used to describe gravitate gravity's effects something gravitron
grabt oh because the two were in distinction to me.
(08:00):
All Right, I like these answers. There's some creative ones there. Um,
there's one that I don't really understand. Like there's a
guy talking about the gravittron. What is a gravitron. I
don't even know. He was confused. He was like, wait
a minute, do you mean the graviton or the gravittron.
I know, but he's referring to something he's familiar with
called the gravitron, and I don't even know what that is.
(08:22):
Like it sounds like a machine he can use to
control gravity or something, you know, the gravitonator. You know,
it does sound kind of more physical, See, doesn't it
gravitron like like that, Like it's a machine that makes
hypes and it's hissing and you know, the steam coming
out the side of it or whatever. It's like a
steampunk gravity accelerator. All right, Well, before I feel like
(08:43):
we people feel like we're making fun of our listeners. Um,
I have to admit that I didn't know what a
graviton was until basically I started talking to you only
a few years ago. Oh yeah. If I had asked
you a few years ago, you might have said it
was some like new sleep kitchen appliance or something, and
said I would have said it was a transformer problem.
Most likely, it's probably the transformer. Guys were bummed if
(09:07):
they can't name a transformer the graviton because the name
is taking my physics. Oh, I don't think that's ever
stopped toy companies, you know, Hold on, are you saying
that these big toy companies don't have a particle physicist
like on retainer for consulting. I would be surprised if
they had a roboticist in their robotic robot department there.
Do you have robotic criticisms of the science behind transformers,
(09:30):
like no, that joint would work differently, or it should
fold in this other way or something. You know, you
have a pet pis about movies that feature physics. That's
that's how robodies. This feel about every movie or anything
that has robots in it. Wow, well I never even like, what,
how could that possibly have the right you know, energy
density output? You need a different kind of cable for that.
(09:52):
Come on, people, But all good answers and all all
good um ways to look at the universe. Yeah, and
as usual, I'm grateful to those random folks out there
who are totally willing to talk to a scruffy looking
scientist about strange, random science questions. So kudos to anybody
out there who's willing to answer science questions with no googling.
(10:14):
That's right, I certainly would run away from you as
fast as I could. Don't say hypothetical like that's happened. Well,
this is a perfect point to take a break. Well,
(10:37):
let's let's get into it. Daniel, step us through here.
What is a graviton? Like, if if you had to
name it in one sentence, what would it be a graviton? Basically,
if you have to describe it in one sentence, what
would that sentence be? How long can this sentence be?
And I just keep going on and on like James
Joy's class one class or maybe two classes. But you know,
all right, Um, A graviton is the particle that trend
(11:00):
smits gravity. In theory, if there is a particle that
transmits gravity, so the force of gravity, the idea is
that it transmits its force. It's forcing us, I guess,
through a particle. And if that exists, that particles called
the graviton. Exactly, that's the idea. And you can imagine,
(11:20):
like you know, gravitational fields have to somehow transmit information
like if the sun disappeared, right then we wouldn't feel
the fact that the sun has disappeared until that information
gets to us. Right, gravitational fields are not instantaneous. Otherwise
you could build a machine to send information fast in
the speed of light by wiggling rocks or something. Okay,
(11:43):
so forces are not instantaneous. Yeah, and so sometimes it
would have been weird, doesn't it get from the Sun
to the Earth. So like the I know, the light
has to travel at the speed of light, but you're saying,
like even the force between two magnets has to travel
at the speed of light. Yeah. Nothing, No information at
all can travel faster than the speed of light. And
(12:03):
then includes information about fields fields that generate forces like
gravitational field or magnetic fields or something. Right. In fact,
that's the way you make light. You can like wiggle
charged particles and they will make light. They will shoot
off photons. All right, So a granton is the particle
that transmits the force of gravity. Uh yeah, And and
(12:24):
is that weird that a force is transmitted by a particle.
It's not weird at all. In fact, it's sort of
a natural concept because every other force that we've ever
seen has a particle associated with it, the particle that
transmits the information for that force, like electromagnetism has photons right. Well,
the other forces, like the weak nuclear force, it has
(12:45):
three particles to do its bidding, the W plus, the
W minus, and the Z. The strong nuclear force has
the gluon. Actually there's eight of them, right, And so
we have these forces electromagnetism, the weak force, and the
strong force, and for those we have good quantum theories.
Those quantum theories describe these particles that transmit the information.
(13:05):
So now we have gravity. We're like, well, cong gravity,
do the same thing, like, how does gravity transmit its
force or its power? Exactly? That's the question is how
is information transmitted for gravity? Right? In Newton's theory. Newton's
original theory, he thought it was instantaneous, right. He thought
if the Sun disappeared or went away or was wiggled,
(13:27):
that we would feel that instantly. Right. But this was
before the advent of relativity. At the instant that Sun disappeared,
the Earth would start to crean out of control and
shoot out into space. That's right, that's Newton's idea. Then
Einstein comes along and he gives us general relativity and
special relativity, and that tells us that information cannot be
transmitted faster than the speed of light, right, And so if,
(13:51):
for example, you change a gravitational field right, then that
information propagates through the gravitational field right at the speed
of light like a shock wave. Kind of exactly like
a shock wave. But here's the thing. What we're talking about, right,
there is a gravitational wave. Right. Like if you turn
on a flashlight and you send out a beam of light,
(14:13):
then you're sending out electromagnetic waves. Right. If you wiggle
the sun, you can wiggle a black hole, then you're
gonna make gravitational waves. Those are not the same thing
as a graviton. They're not They're not. No, a graviton
is two gravitational waves what photons are to a beam
of light. I remember that general relativity describes the universe
(14:35):
really really well. But we think that the universe is
quantum mechanical. We think for the universe is is made
up of little bits. And in the same way that
a beam of light turns out to be made up
of tiny little photons. The idea is maybe gravity and
gravitational waves are made up of tiny little gravitons. It
sounds like the days that, like, right now, I'm sitting
(14:57):
here in my studio and I'm being pulled down owned
by gravity towards the center of the Earth. And you're
saying that that somehow, being like, somehow the Earth is
shooting gravitons at me, or it's or I'm shooting gravitons
at the Earth. But what does that mean for for me, Daniel,
for my universe? I think the important thing to think
about is how fields change. So the Earth. If the
(15:19):
Earth is not moving right relative to you, then you
have a constant gravitational field and so there are no
gravitational waves being propagated there and um, so you don't
need to build it out of any gravitons. But if
the Earth changes, right, then that information comes as a
gravitational wave, which is built out of gravitons. I see, so,
(15:39):
and then if I see, if I stand up, you're saying,
then there's some gravitons exchange between my my, my behind
and the center of the Earth. I really wanted to
get through a whole podcast without talking about your behind,
but all right, let's do it. Yes, exactly, because remember
that the Earth is pulling on you, right, and you
are also pulling on the Earth with the same force. Right. Um.
(16:02):
One way I heard somebody say, cleverly, is that like,
on the surface of the Earth, you weigh I don't
know what a hundred fifty pounds, right, but on the
surface of the of Jorge, the Earth weighs a hundred
and fifty pounds. There's a force of attraction between you
and the Earth, and anytime that changes, you're gonna need
gravitational little gravitational waves made out of even smaller gravitons.
(16:24):
And the whole idea is just an extrapolation from the
other fields. Right. We see that it happens for electromagnetism,
We see that it happens for the weak force and
the strong force, and so we like patterns. We'd like
to say, maybe this is really a deep thing and
if it. If so, why doesn't it also apply to gravity? Okay,
so if I stand up, then are there gravitons exchanged
between me and the Earth? Is that kind of what
(16:46):
you're saying, is like it's about the changes in the
gravitational fields. Yeah, exactly. Um, information about the gravitational field
can be conveyed, and we think that it's probably made up,
but it's sort of the microscopic level of gravitons, right,
They are the basic quanta the same way that we
(17:06):
you know, we think that light. We know that light
is made out of tiny little bits we call photons. Right.
We think that all gravitational information is built out of
tiny little bits called gravitons. But of course we've never
seen them. It's just theoretical. It's it's purely a concept
extrapolated from other examples, right, because I think a lot
of people maybe forget that it's not just light that's
(17:26):
made out of photons. It's just it's the electromagnetic force itself, right,
like between two magnets when you're when they're pulling or
pushing each other, they're shooting each other with photons, right
in some ways, yeah, exactly. And remember a photon is
just like a ripple in some quantum field. These days,
we don't think about the basic thing in the universe
(17:47):
is being particles. Right. You probably have an image in
your mind of like two particles pushing each other by
shooting them each other with little laser guns or something. Right,
instead think about paint pong balls. Maybe this is microscopic, right,
So instead think about like two particles on our waterbed, right,
and every time one of the moves it affects the
other one. That's like it ripples over to the other one.
(18:09):
And those ripples are ripples in the photonic quantum field, right,
and those are what we call photons. We reimagine these
particles as ripples in these sort of base, more base objects,
these deeper and more fundamental objects called quantum fields. And
a big part of the theory is that these ripples
have a minimum size, right, Like, you can't have an
(18:30):
infinitely small ripple. At some point they sort of like
become chunky too, like exactly. Then that's where Einstein, you
sort of ran up against the wall. Right. Einstein correctly
predicts that gravity takes time to propagate. For example, his
his theory has gravitational waves in it, and we've seen them, right,
that's awesome. But what we don't know is if those
(18:51):
waves are made of tiny little bits, like if you
zoom in on them enough and you break them down
into tiny little bits, like if you turn down a
flashlight really really low. Eventually, if you have a really
awesome flashlight, you'll get it down to the point where
it's sending out one photon at a time. Right, there's
a minimum amount of energy that has to come out
of your flashlights, either off or sending out one photon
(19:12):
per second. I can't send out half a photon. And
so it is that there's maybe a minimum amount of gravity,
and that's what a graviton is. Yeah, exactly. You know,
think about it maybe spatially if that's helpful. Like, you know,
the universe has pixels, right, we talked about space maybe
being sliced up into little pixels. Well, this is sort
of like pixelization of gravity, Like is there a minimum
(19:33):
bit of gravity? And you know, we don't know. There's
a very strong argument that there should be because everything
else in the universe seems to be quantum mechanical. Right.
The universe, as as you like to say, is chunky
and a creamy peanut butter, right, and so we think
everything should behave those rules. But our theory of gravity
general relativity is not a quantum theory, right, It's a
(19:56):
classical theory. It assumes that you could have an infinitely
tiny amount of gravity, or that you can have mass
in an infinite amount in a tiny little dot right
of singularity. Those things are are at odds with quantum mechanics. Yeah,
because the difference I think you've told me this before,
is that you know, all the other forces act via
quantum field, but we don't know if gravity has a
(20:21):
gravity field in the universe, right, Like gravity kind of
has a special place among the other forces, and that
it's more like a bending of time and space exactly.
But we hate special cases, right, Physicists like to generalize,
We like to see patterns. We like to organize everything together.
So to say, like everything works this way except for gravity.
(20:41):
Things run in this certain manner except for gravity. You
think nobody special. Well, it's something is special. Then it's
a clue. Right, So it's a clue that about how
the universe works at some really interesting, deep fundamental level.
So before we believe that, we'd like to remove all
other possible explanations. And it's a pretty an argument that
every other force we've ever seen is a quantum force
(21:03):
can be described in terms of particles and fields. So
we're going to try really hard to make that work.
Also for gravity, before we declare that it's impossible. Gravity
special because you can think of it as a bending
of space and time, whereas all the other forces you
can't think of them as a bending of space and time. Right,
like they the the way that it makes sense to
think about those forces is quantum physics. But the way
(21:25):
it makes sense to think about gravity is as a
bending of space and time. And so that's that's kind
of the problem, isn't it. That is a problem. But
like everything in physics, you can describe in multiple ways,
and so you can build up a theory of gravity
that comes from particles and fields. Right, you can start
with a gravitational field, right, a quantum field, and you
can have gravitons zipping around, and then you can say, well,
(21:48):
can I build that? Can I sort of build this
mental model and can I have it predict the same
things that general relativity predicts? Right? Because general relativity very successful,
that description gravity works really well. But can I get
the same description building it up in another way? And
that's sort of the theoretical challenge, And so far the
(22:09):
answer is no. Like they have not yet been able
to build a theory of gravity that starts from quantum
bits and explains all the same stuff as Einstein's theory.
They haven't because it just doesn't work. They just cannot
make it work. Like they put a theory together using
the same strategies as they have for electromagnetism and the
weak force and the strong force, and it just doesn't work.
(22:29):
It gives nonsense answers, like it says, if you do
this experiment, then you will measure infinity mass or you
will build be an infinite amount of energy released, which
is nonsense. Right, You can't have an infinite amount of energy,
So it predicts things which cannot be true, which just
means that we have a problem with the calculation, you know,
and we had similar problems with every other quantum field theory,
(22:51):
but we figured them out. But what is it about
gravity in particular? You think that is giving you so
much trouble? Gravity has this weird feature that it gets
stronger when there's more energy, right, because gravity essentially is
the bending of space due to energy, right, that's the
way we like to think about it. So as the
energy goes up, then you get stronger gravity, and then
(23:11):
because you have stronger gravity, the energy has gone up,
and so you get this feedback effect where these infinities
crop up much more easily than in other forces, because,
like electromagnetism doesn't get stronger when you have more energy,
So it's kind of like um, it's more tied into
the very nature of the universe maybe, and so it
doesn't quite work, that's right. And if it is a
(23:32):
quantum field, and if it does have a quantum particle,
it will still be different. It will still be unique.
Like the graviton. We think it has this weird kind
of way of spinning, like all the other particles that
transmit forces that have either spin one or spin zero.
But the graviton, the only way people have even become
close to making it work is having it have a
(23:53):
lot more ways to spin, so it's spin two, which
means there's five different ways it can spin instead of
just one way three ways. So it would definitely be
a different beast if we if we were able to
make a quantum theory of gravity, it would not look
that similar to like the strong force or the weak
force or electromagnetism. You have to kind of give it
a few more bells and whistles, and that's just to
(24:15):
try to make it work right, And even still those
theories don't work. The only theory of quantum gravity that
works at all is one that starts very very basic, right,
like string theory and loop quantum gravity. These are attempts
to start from a very different place and build up
quantum fields themselves. And they have succeeded in making some
(24:35):
useful theories of quantum gravity, but none that we can
test yet. What would it mean if it is, if
the graviton does exist and it is true? Right, it
would mean that the bending of space and time is
like you said, pixelated or chunky, or you know you can.
I can't bend space and time perfectly smoothly, and it's
sort of kinks. There's a knob there and instead of
rotating smoothly that has little divots right at one or
(24:57):
two or three you can't have you can't turn to
two and a half. Right. But also, I think it
would mean something much deeper, Right, It would mean that
gravity really is a force the way we think about
the other forces. We're trying to squeeze gravity into this mold.
Can we describe it using the same mathematical tools we've
used for the other forces. If we can succeed, then
we can say something deep about gravity, like, oh, yeah,
(25:18):
it's just a force like the other ones. It happens
to have this ability to bend space and time, which
is weird and interesting. We have to ask why is that?
You know? And can we connected to the other forces?
But we've met a huge step forward and sort of
unifying all the forces together, seeing them all as one.
If we can't, then you're right, gravity is weird and special.
And then we have to ask what makes it weird
and special? Why does it seem so much like a
(25:41):
force if it's not really? All right? Um, so it
may or may not exist, this graviton, and it may
or may not totally change our our our understanding of
the whole universe. And so then I think that brings
us to the question of how are we gonna result this?
How are we going to find this thing or not
find it or conclude that it doesn't exist. So let's
get into that first. Let's take a quick break. All right,
(26:14):
we're talking about the graviton, and we're saying that it's
it's kind of the minimum little ripple that that maybe
gravity acts through. That if it exists, it means gravity
is like the other forces. And if it doesn't exist,
it means gravity is something totally different and special. So
how are how are we going to find out what
the answer is? Saying, Well, there's two basic approaches. One
(26:35):
is two sort of look for evidence of it happening already, right,
And we do this in astrophysics all the time. We
just say, well, let's just look at into the universe
and find something crazy which reveals to us the truth.
Like when we're studying dark matter, and we saw the
collisions of two galactic clusters that showed us how dark
matter gets separated from normal matter. So in this case,
(26:57):
we'd be looking for like really huge gravity tational waves.
So we've already seen gravitational waves, right, Those are evidence
of the wiggling of a gravitational field when like black
holes collide or whatever. And it's hard to see them, right,
It's really difficult to see them because they're really faint,
and so it's even harder to see whether they're made
of little bits or not. Right, Like, we can just
(27:19):
barely see them, so it's hard to tell if they're
what they're made out of. So what you need to
do is spot like a really mondo gravitational wave, one
that was big enough that you could sort of zoom
in on it and see what is made out of
something really big, like a like a mega tron. I
think I call it a gravitron. Nader or something, so
(27:44):
so you need to find It's so the gravitas they
exists are so small and weak you can't just like
measure them with your finger, right, You're saying, we need
to find something really crazy happening in the universe where
that's producing so many of these and such an amount
that then you can notice them. Yeah exactly. That's one strategy.
The other strategy is to try to make them here
(28:05):
on Earth. And you know the go to place for
making crazy stuff here on Earth, of course, is the
particle collider. Like you want to make something new, something
you're not sure as possible, just keep smashing particles together
and eventually it will come out. And so you're saying,
one way to maybe study graviton is to make gravitons. Yeah, exactly.
And that's the magic of a particle collider is you
(28:27):
throw stuff together and if something can exist, then you
will see it. And so if we smash protons together
often enough, and gravitons are a thing, that eventually those
two protons one a trillion or one or the quadrillion
collisions will turn into a graviton, and that graviton will
then turn into something else that we can see. Hold
(28:47):
on a second, Daniel, here, you're saying that at the
particle collider, you're taking protons, smashing them together and then
transforming them into gravitons. We want to, we're open to
that would be come true. So far, no, so so
a graviton is a transformer if you find it's what
I'm saying, I totally walked into that. It's exactly. Or
(29:09):
the particle collider is the transformer because it transforms protons
into other kinds of stuff. But you know there's a
huge difference. They're transformer when it changes. It's all the
same stuff, just rearranged in a different shape. Right. The
dinosaur is actually the robot, just with the head where
the tail is or whatever. But in this case, we're
not doing that or not. We're not rearranging what's inside
(29:30):
the proton into a different shape to make a graviton.
The proton and nilin it turns into nothing. It turns
into raw energy, which that can then be turned into
something new. That's how exactly you explore the universe by
turning this raw energy into any of the stuff that
he can turn into. So it's more like alchemy than transformation.
(29:51):
That's uh, and those are totally different for sure. Yeah, exactly.
If gravitons exist, then the idea is we could make
them by colliding proton together. Eventually, one out of a
jillion times we would make them, and then we would
see them turn into other particles like a pair of electrons. Right. Essentially,
a graviton would look sort of like another version of
the photon. Would you be able to see it though?
(30:13):
Wouldn't it be so weak and small that you be
very very very very difficult to see. Well, that's the
cool thing about the collider, right, I feel like I'm
a collider evangelist today, is that things that are really
weak that are hard to see just turned into things
that are really rare at the collider. And so the
more collisions you make, the more you can see rare
stuff like yeah, it's weak, which means every time a
(30:35):
proton collides, you've got to roll a like trillion sided
die to figure out what's going to happen, and only
one of those sides says a graviton is made. But
that's cool. If you roll the die at trillion times
a day, then you're probably gonna get a graviton a day,
So it sort of sounds like you're basically looking for
effects that you can point to and say, hey, that
means that there's a graviton somewhere in there, like when
(30:58):
two black holes collide or when you smash these protons together. Exactly.
That's what we do with colliders. We look for unique
signatures of new particles, something that says, oh, this has
to be a new particle. It's very likely to be
a new particle that can't be explained in any other way.
And so we have theories of how gravitons would look
in our detectors, and so we're looking for them. Um.
(31:18):
So far, we haven't found a hint of gravitons and
our detectors, um, which just means that you know, they're
basically smaller than we can see. Um, so we could
just keep looking. What you said, you haven't seen a
hint of them, so like zero zero nothing. Yeah, exactly.
What we've seen so far is totally consistent with Einstein's
theory of general relativity. Well, what do you think is
(31:40):
more more likely, just in your personal opinion, do you
think the graviton exists or do you think maybe it doesn't.
End Gravity is a very special kind of force. I
think that we're going to figure out that everything is
quantum mechanical. I think the quantum mechanics is just so
fundamental to everything we've seen in the universe except for
this one thing that it seems more likely to me
(32:01):
that we just haven't understood that one last thing yet.
Um that it's you know, it's the one thing that's
has that's left over that hasn't been translated yet into
modern theories of physics. Um. So that's my suspicion that
everything is quantum mechanical, because if, if, if most things
are quantum mechanical, it's hard to imagine how you can't
have everything quantum mechanical, you know, like where's the interface
(32:23):
between the quantum mechanical stuff and then non quantum mechanical stuff.
They have to interact and so they have to both
be quantum mechanical to sort of talk to each other. Yeah,
so you're really hoping that it's true, because then that
would be like the gravytan on your mash potatoes. No, no,
I suspect it's true. I hope it's not, because it
would be a huge shock if it wasn't right. And
(32:44):
that's the best case scenario for science is learning something
which is a deep shock to like the fundamental community
to say, like what that's impossible. That makes us rethink everything. Awesome,
that's what science is about, right, not like, yeah, we're
pretty sure it's quantum mechanical and turns out it is
check as much less exciting, even if I think that's
most likely the reality. Well that's my personal philosophy. Aim high,
(33:09):
but have low expectations. Well, I hope that's working for you. Well,
I have expectations, so it doesn't. I won't be disappointed
no matter how the gravy tastes. You're happy with it
if it's made out of big lumps or tiny little gravitons.
All right, So I think that we covered what a
graviton is, right, Daniel, Yeah, how would you summarize it?
I would say it's like gravy with fore and on
(33:31):
top of the transformer and then mixed together with some alchemy.
That's that's what I thought out of this, and then
take two of those and smash them together. No, I
think I think it's the idea that, um, you know,
gravity as a force has to transmit in some way, right, like, um,
you know, it's just it's not like an instantaneous thing,
(33:51):
like a magical thing, so it has to transmit in
some way and and possibly in a minimum way. And
that's kind of what this graviton is, right, the idea
that something is transmitting the force and prep you are
officially a quantum physicist. All right, Well, we hope you
enjoyed that. This is one of my favorite topics in
physics because it's theoretical, it's experimental, it's experimentally theoretical, it's
(34:12):
theoretically experimental. It's crazy, it's fascinating, and we don't know
what the answer is. But someday humans will somedays somebody
will know. Is gravity quantum mechanical or is it special? Great?
Thanks for joining us, See you next time. Before you
(34:33):
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 More podcast from
(34:56):
my heart Radio, visit the I heart Radio app, Apple podcasts,
or wherever you listen to your favorite shows. H
Hey, hey, it's that time again. What are we talking
about today? It's time to talk about particle names, my
favorite subject. Hey, don't blame me. There are a lot
of particles out there. All right, let's do it, Daniel. Well,
today's game is I'm gonna give you a word and
you have to guess whether it's the name of a
fundamental particle or the name of a character in the Transformers.
(00:32):
All right, I'm ready to me alright, first one, Megatron,
that one down to give me. That's definitely a Transformer.
All right, that was the warm up. How about Galvatron.
I'm gonna go with particle alright, Computron, I'm gonna go
with the Transformer or eighties computer company? Alright. Last one
(00:52):
is tripp to con That sounds more like a convention
for pleasant nerds. Hey, I want to go to that.
That sounds awesome. Yeah, alright, Which ones are particles and
which ones are Transformers? All right? It was a bit
of a trick question. They were all names of Transformers.
What I had to do a bit of deep research.
(01:14):
But those are actual Transformer character names. Oh man, you
got me, all right, but you have to promise me
if you ever discover a particle Daniel at the large
Headron collider. You have to name it Mega Tromp done.
(01:45):
Hi am Jorge. I'm a cartoonists and the creator of
PhD comics. Hi I'm Daniel. I'm a particle physicist, a
closet transformer geek, and definitely a nerd. And Welcome to
our podcast. Daniel and Jorge explain eighties toy franchises. No,
I mean Daniel and Orge explained the universe a production
of My Heart Radio. I Heart Radio is going to
(02:05):
get sued now by mattel or whoever puts out the transformers.
This is the first domino, isn't it the beginning of
the downfall of the podcast? Um? But welcome to our podcast,
in which we take crazy, amazing things that blow your
mind and try to relate them to silly, fun easily
understandable things like robots that turn into cars or airplanes
or you know, dinosaurs. Television transforms are very versatile. I
(02:28):
never understood the dinosaur thing, Like, you're already a killer robot.
What's the advantage of transforming into a dinosaur? Like? Seriously,
I mean, think about this robot versus dinosaur. Who wins
robot every time, right, I think they're just trying to
blend in with the other dinosaurs. All these are prehistoric transformers,
robots in disguise. So if transformers had come to Earth
(02:48):
before the dinosaurs, wouldy have transformed into like insects and
like trilobytes and stuff like that. They did, they there's
this transformer for everything. But anyways, welcome to a podcast
in which we talk about all the things in universe,
the big ones, the small ones, the ones that maybe
don't even exist. That's right, and we love delving into
these theoretical hypothetical topics, and so today we're going to
(03:10):
talk about a very interesting concept, right Daniel, which is
something that maybe in your everyday life, affecting you on
a daily, every second of your life basis um, but
which physicists don't even know if it exists or not.
That's right. This relates to something you experience every day,
but physics still doesn't really understand that kind of thing,
(03:31):
which in two hundred years people will look back and say, man,
I wish I had had those ideas. I totally would
have gotten the Nobel Prize. The puzzle was right there
in front of them and it's something that I think
you've told me this before that if it exists, it
may totally upend all of our theories about physics, right,
that's right. One of the challenges with this kind of
idea is that we don't even really know how to
(03:52):
form the idea, Like the idea itself has problems, not
to mention whether or not it exists, but we can't
even really seem to get it to behave its on
the page, so to the On the podcast, we'll be
talking about the graviton. What is the graviton? Is it
a transformer for a transformer? Is it a particle? Is it?
(04:18):
And how is it pronounced? Really? Is it graviton or
is it gravyton? Or yeah? What kind of transformer would
the gravyton be? Shoot streams of hot gravy at you
or something transformed into a gravy bowl? Oh? Man, so
terrifying grav versus turkey tron, based, the based or based
(04:40):
or bot. No, but it's a funny name. And you know,
you are often a critic of physics naming, and so
you know, if the folks have done a good job
in this case, then the name should be pretty clear, right,
that's your mattress, name something in a clear way, so
not knowing anything about it, just knowing the name. What
do you imagine the A baton means the gravytan um
(05:04):
you has something to do with graves or I imagine
it has something to do with gravity, like a gravity thing.
I like how you first went for gravy, second went
for graves, and only third on the Physics podcast considered
we might be talking about gravity. So yeah, it's a
particle related to gravity right now? Yeah, exactly, and we'll
be talking exactly about what that means. And we've touched
(05:26):
on this a few times, but this is the scenario
where a particle exists theoretically and it's already been given
a name before it's discovered. If some particles we find them,
then we argue about how to name it. Right, some
particles are named before they're discovered, like we have the
idea for them, and then we go ahead and find it.
We already know what to call it, like the Higgs boson.
(05:48):
So let's say your physicist and you think of something
on the on your notepad, or you find something. Do
you think most physicists have sort of a pre name
in their minds when they're looking for these things, or
even if they're I don't think they're looking for these things.
I don't know. Um, but I haven't noticed recently there
are a lot more names being given to ideas. I
think this is, you know, young people coming up and
(06:10):
recognizing the value of branding, and so every sort of
new idea that something that comes up with has like
a slick sounding name that's associated with it so that
it sticks in people's heads. It's not just some complicated
new idea, you know, it's it's it's got some branding
to it. Cool. Um, But of course I've already thought
about the name of a particle I would discover. Oh yeah,
(06:31):
I mean my last name ends with S O N.
So it's very clearly I got to call it the
White Song. I know, you would have to call it
the whites some ton. That sounds like some complicated Icelandic person. Cool.
So today we'll be talking about what is the graviton
and does it exist? And what does it mean if
we ever actually find this particle? Right, and how would
(06:54):
we look for it and what would it mean? Yeah,
so it sounds like something either out of a Transformers
movie or some thing out of a physics textbook. But
we were wondering, as usual, how many people out there
know what a graviton is. So I walked around wherever
I was in the world, and I asked people what
they knew about the graviton. Could they explain it? Did
they have any idea? Had they heard it before? Did
(07:15):
they play with one when they were a kid. So
before you listen to these, think about it for a second.
If you were approached by a physicist at an airport
in London, what would you answer to the question what
is a graviton? Here? It's what people had to say.
I heard of it, but I don't know it. It's problem.
But you know grav with you? Yeah, okay, I heard
(07:38):
about gravity, but I don't I've ever heard about a
material like graviton. No. Gravitons, Yes, they're the theoretical particle
that is used to describe gravitate gravity's effects something gravitron
grabt oh because the two were in distinction to me.
(08:00):
All Right, I like these answers. There's some creative ones there. Um,
there's one that I don't really understand. Like there's a
guy talking about the gravittron. What is a gravitron. I
don't even know. He was confused. He was like, wait
a minute, do you mean the graviton or the gravittron.
I know, but he's referring to something he's familiar with
called the gravitron, and I don't even know what that is.
(08:22):
Like it sounds like a machine he can use to
control gravity or something, you know, the gravitonator. You know,
it does sound kind of more physical, See, doesn't it
gravitron like like that, Like it's a machine that makes
hypes and it's hissing and you know, the steam coming
out the side of it or whatever. It's like a
steampunk gravity accelerator. All right, Well, before I feel like
(08:43):
we people feel like we're making fun of our listeners. Um,
I have to admit that I didn't know what a
graviton was until basically I started talking to you only
a few years ago. Oh yeah. If I had asked
you a few years ago, you might have said it
was some like new sleep kitchen appliance or something, and
said I would have said it was a transformer problem.
Most likely, it's probably the transformer. Guys were bummed if
(09:07):
they can't name a transformer the graviton because the name
is taking my physics. Oh, I don't think that's ever
stopped toy companies, you know, Hold on, are you saying
that these big toy companies don't have a particle physicist
like on retainer for consulting. I would be surprised if
they had a roboticist in their robotic robot department there.
Do you have robotic criticisms of the science behind transformers,
(09:30):
like no, that joint would work differently, or it should
fold in this other way or something. You know, you
have a pet pis about movies that feature physics. That's
that's how robodies. This feel about every movie or anything
that has robots in it. Wow, well I never even like, what,
how could that possibly have the right you know, energy
density output? You need a different kind of cable for that.
(09:52):
Come on, people, But all good answers and all all
good um ways to look at the universe. Yeah, and
as usual, I'm grateful to those random folks out there
who are totally willing to talk to a scruffy looking
scientist about strange, random science questions. So kudos to anybody
out there who's willing to answer science questions with no googling.
(10:14):
That's right, I certainly would run away from you as
fast as I could. Don't say hypothetical like that's happened. Well,
this is a perfect point to take a break. Well,
(10:37):
let's let's get into it. Daniel, step us through here.
What is a graviton? Like, if if you had to
name it in one sentence, what would it be a graviton? Basically,
if you have to describe it in one sentence, what
would that sentence be? How long can this sentence be?
And I just keep going on and on like James
Joy's class one class or maybe two classes. But you know,
all right, Um, A graviton is the particle that trend
(11:00):
smits gravity. In theory, if there is a particle that
transmits gravity, so the force of gravity, the idea is
that it transmits its force. It's forcing us, I guess,
through a particle. And if that exists, that particles called
the graviton. Exactly, that's the idea. And you can imagine,
(11:20):
like you know, gravitational fields have to somehow transmit information
like if the sun disappeared, right then we wouldn't feel
the fact that the sun has disappeared until that information
gets to us. Right, gravitational fields are not instantaneous. Otherwise
you could build a machine to send information fast in
the speed of light by wiggling rocks or something. Okay,
(11:43):
so forces are not instantaneous. Yeah, and so sometimes it
would have been weird, doesn't it get from the Sun
to the Earth. So like the I know, the light
has to travel at the speed of light, but you're saying,
like even the force between two magnets has to travel
at the speed of light. Yeah. Nothing, No information at
all can travel faster than the speed of light. And
(12:03):
then includes information about fields fields that generate forces like
gravitational field or magnetic fields or something. Right. In fact,
that's the way you make light. You can like wiggle
charged particles and they will make light. They will shoot
off photons. All right, So a granton is the particle
that transmits the force of gravity. Uh yeah, And and
(12:24):
is that weird that a force is transmitted by a particle.
It's not weird at all. In fact, it's sort of
a natural concept because every other force that we've ever
seen has a particle associated with it, the particle that
transmits the information for that force, like electromagnetism has photons right. Well,
the other forces, like the weak nuclear force, it has
(12:45):
three particles to do its bidding, the W plus, the
W minus, and the Z. The strong nuclear force has
the gluon. Actually there's eight of them, right, And so
we have these forces electromagnetism, the weak force, and the
strong force, and for those we have good quantum theories.
Those quantum theories describe these particles that transmit the information.
(13:05):
So now we have gravity. We're like, well, cong gravity,
do the same thing, like, how does gravity transmit its
force or its power? Exactly? That's the question is how
is information transmitted for gravity? Right? In Newton's theory. Newton's
original theory, he thought it was instantaneous, right. He thought
if the Sun disappeared or went away or was wiggled,
(13:27):
that we would feel that instantly. Right. But this was
before the advent of relativity. At the instant that Sun disappeared,
the Earth would start to crean out of control and
shoot out into space. That's right, that's Newton's idea. Then
Einstein comes along and he gives us general relativity and
special relativity, and that tells us that information cannot be
transmitted faster than the speed of light, right, And so if,
(13:51):
for example, you change a gravitational field right, then that
information propagates through the gravitational field right at the speed
of light like a shock wave. Kind of exactly like
a shock wave. But here's the thing. What we're talking about, right,
there is a gravitational wave. Right. Like if you turn
on a flashlight and you send out a beam of light,
(14:13):
then you're sending out electromagnetic waves. Right. If you wiggle
the sun, you can wiggle a black hole, then you're
gonna make gravitational waves. Those are not the same thing
as a graviton. They're not They're not. No, a graviton
is two gravitational waves what photons are to a beam
of light. I remember that general relativity describes the universe
(14:35):
really really well. But we think that the universe is
quantum mechanical. We think for the universe is is made
up of little bits. And in the same way that
a beam of light turns out to be made up
of tiny little photons. The idea is maybe gravity and
gravitational waves are made up of tiny little gravitons. It
sounds like the days that, like, right now, I'm sitting
(14:57):
here in my studio and I'm being pulled down owned
by gravity towards the center of the Earth. And you're
saying that that somehow, being like, somehow the Earth is
shooting gravitons at me, or it's or I'm shooting gravitons
at the Earth. But what does that mean for for me, Daniel,
for my universe? I think the important thing to think
about is how fields change. So the Earth. If the
(15:19):
Earth is not moving right relative to you, then you
have a constant gravitational field and so there are no
gravitational waves being propagated there and um, so you don't
need to build it out of any gravitons. But if
the Earth changes, right, then that information comes as a
gravitational wave, which is built out of gravitons. I see, so,
(15:39):
and then if I see, if I stand up, you're saying,
then there's some gravitons exchange between my my, my behind
and the center of the Earth. I really wanted to
get through a whole podcast without talking about your behind,
but all right, let's do it. Yes, exactly, because remember
that the Earth is pulling on you, right, and you
are also pulling on the Earth with the same force. Right. Um.
(16:02):
One way I heard somebody say, cleverly, is that like,
on the surface of the Earth, you weigh I don't
know what a hundred fifty pounds, right, but on the
surface of the of Jorge, the Earth weighs a hundred
and fifty pounds. There's a force of attraction between you
and the Earth, and anytime that changes, you're gonna need
gravitational little gravitational waves made out of even smaller gravitons.
(16:24):
And the whole idea is just an extrapolation from the
other fields. Right. We see that it happens for electromagnetism,
We see that it happens for the weak force and
the strong force, and so we like patterns. We'd like
to say, maybe this is really a deep thing and
if it. If so, why doesn't it also apply to gravity? Okay,
so if I stand up, then are there gravitons exchanged
between me and the Earth? Is that kind of what
(16:46):
you're saying, is like it's about the changes in the
gravitational fields. Yeah, exactly. Um, information about the gravitational field
can be conveyed, and we think that it's probably made up,
but it's sort of the microscopic level of gravitons, right,
They are the basic quanta the same way that we
(17:06):
you know, we think that light. We know that light
is made out of tiny little bits we call photons. Right.
We think that all gravitational information is built out of
tiny little bits called gravitons. But of course we've never
seen them. It's just theoretical. It's it's purely a concept
extrapolated from other examples, right, because I think a lot
of people maybe forget that it's not just light that's
(17:26):
made out of photons. It's just it's the electromagnetic force itself, right,
like between two magnets when you're when they're pulling or
pushing each other, they're shooting each other with photons, right
in some ways, yeah, exactly. And remember a photon is
just like a ripple in some quantum field. These days,
we don't think about the basic thing in the universe
(17:47):
is being particles. Right. You probably have an image in
your mind of like two particles pushing each other by
shooting them each other with little laser guns or something. Right,
instead think about paint pong balls. Maybe this is microscopic, right,
So instead think about like two particles on our waterbed, right,
and every time one of the moves it affects the
other one. That's like it ripples over to the other one.
(18:09):
And those ripples are ripples in the photonic quantum field, right,
and those are what we call photons. We reimagine these
particles as ripples in these sort of base, more base objects,
these deeper and more fundamental objects called quantum fields. And
a big part of the theory is that these ripples
have a minimum size, right, Like, you can't have an
(18:30):
infinitely small ripple. At some point they sort of like
become chunky too, like exactly. Then that's where Einstein, you
sort of ran up against the wall. Right. Einstein correctly
predicts that gravity takes time to propagate. For example, his
his theory has gravitational waves in it, and we've seen them, right,
that's awesome. But what we don't know is if those
(18:51):
waves are made of tiny little bits, like if you
zoom in on them enough and you break them down
into tiny little bits, like if you turn down a
flashlight really really low. Eventually, if you have a really
awesome flashlight, you'll get it down to the point where
it's sending out one photon at a time. Right, there's
a minimum amount of energy that has to come out
of your flashlights, either off or sending out one photon
(19:12):
per second. I can't send out half a photon. And
so it is that there's maybe a minimum amount of gravity,
and that's what a graviton is. Yeah, exactly. You know,
think about it maybe spatially if that's helpful. Like, you know,
the universe has pixels, right, we talked about space maybe
being sliced up into little pixels. Well, this is sort
of like pixelization of gravity, Like is there a minimum
(19:33):
bit of gravity? And you know, we don't know. There's
a very strong argument that there should be because everything
else in the universe seems to be quantum mechanical. Right.
The universe, as as you like to say, is chunky
and a creamy peanut butter, right, and so we think
everything should behave those rules. But our theory of gravity
general relativity is not a quantum theory, right, It's a
(19:56):
classical theory. It assumes that you could have an infinitely
tiny amount of gravity, or that you can have mass
in an infinite amount in a tiny little dot right
of singularity. Those things are are at odds with quantum mechanics. Yeah,
because the difference I think you've told me this before,
is that you know, all the other forces act via
quantum field, but we don't know if gravity has a
(20:21):
gravity field in the universe, right, Like gravity kind of
has a special place among the other forces, and that
it's more like a bending of time and space exactly.
But we hate special cases, right, Physicists like to generalize,
We like to see patterns. We like to organize everything together.
So to say, like everything works this way except for gravity.
(20:41):
Things run in this certain manner except for gravity. You
think nobody special. Well, it's something is special. Then it's
a clue. Right, So it's a clue that about how
the universe works at some really interesting, deep fundamental level.
So before we believe that, we'd like to remove all
other possible explanations. And it's a pretty an argument that
every other force we've ever seen is a quantum force
(21:03):
can be described in terms of particles and fields. So
we're going to try really hard to make that work.
Also for gravity, before we declare that it's impossible. Gravity
special because you can think of it as a bending
of space and time, whereas all the other forces you
can't think of them as a bending of space and time. Right,
like they the the way that it makes sense to
think about those forces is quantum physics. But the way
(21:25):
it makes sense to think about gravity is as a
bending of space and time. And so that's that's kind
of the problem, isn't it. That is a problem. But
like everything in physics, you can describe in multiple ways,
and so you can build up a theory of gravity
that comes from particles and fields. Right, you can start
with a gravitational field, right, a quantum field, and you
can have gravitons zipping around, and then you can say, well,
(21:48):
can I build that? Can I sort of build this
mental model and can I have it predict the same
things that general relativity predicts? Right? Because general relativity very successful,
that description gravity works really well. But can I get
the same description building it up in another way? And
that's sort of the theoretical challenge, And so far the
(22:09):
answer is no. Like they have not yet been able
to build a theory of gravity that starts from quantum
bits and explains all the same stuff as Einstein's theory.
They haven't because it just doesn't work. They just cannot
make it work. Like they put a theory together using
the same strategies as they have for electromagnetism and the
weak force and the strong force, and it just doesn't work.
(22:29):
It gives nonsense answers, like it says, if you do
this experiment, then you will measure infinity mass or you
will build be an infinite amount of energy released, which
is nonsense. Right, You can't have an infinite amount of energy,
So it predicts things which cannot be true, which just
means that we have a problem with the calculation, you know,
and we had similar problems with every other quantum field theory,
(22:51):
but we figured them out. But what is it about
gravity in particular? You think that is giving you so
much trouble? Gravity has this weird feature that it gets
stronger when there's more energy, right, because gravity essentially is
the bending of space due to energy, right, that's the
way we like to think about it. So as the
energy goes up, then you get stronger gravity, and then
(23:11):
because you have stronger gravity, the energy has gone up,
and so you get this feedback effect where these infinities
crop up much more easily than in other forces, because,
like electromagnetism doesn't get stronger when you have more energy,
So it's kind of like um, it's more tied into
the very nature of the universe maybe, and so it
doesn't quite work, that's right. And if it is a
(23:32):
quantum field, and if it does have a quantum particle,
it will still be different. It will still be unique.
Like the graviton. We think it has this weird kind
of way of spinning, like all the other particles that
transmit forces that have either spin one or spin zero.
But the graviton, the only way people have even become
close to making it work is having it have a
(23:53):
lot more ways to spin, so it's spin two, which
means there's five different ways it can spin instead of
just one way three ways. So it would definitely be
a different beast if we if we were able to
make a quantum theory of gravity, it would not look
that similar to like the strong force or the weak
force or electromagnetism. You have to kind of give it
a few more bells and whistles, and that's just to
(24:15):
try to make it work right, And even still those
theories don't work. The only theory of quantum gravity that
works at all is one that starts very very basic, right,
like string theory and loop quantum gravity. These are attempts
to start from a very different place and build up
quantum fields themselves. And they have succeeded in making some
(24:35):
useful theories of quantum gravity, but none that we can
test yet. What would it mean if it is, if
the graviton does exist and it is true? Right, it
would mean that the bending of space and time is
like you said, pixelated or chunky, or you know you can.
I can't bend space and time perfectly smoothly, and it's
sort of kinks. There's a knob there and instead of
rotating smoothly that has little divots right at one or
(24:57):
two or three you can't have you can't turn to
two and a half. Right. But also, I think it
would mean something much deeper, Right, It would mean that
gravity really is a force the way we think about
the other forces. We're trying to squeeze gravity into this mold.
Can we describe it using the same mathematical tools we've
used for the other forces. If we can succeed, then
we can say something deep about gravity, like, oh, yeah,
(25:18):
it's just a force like the other ones. It happens
to have this ability to bend space and time, which
is weird and interesting. We have to ask why is that?
You know? And can we connected to the other forces?
But we've met a huge step forward and sort of
unifying all the forces together, seeing them all as one.
If we can't, then you're right, gravity is weird and special.
And then we have to ask what makes it weird
and special? Why does it seem so much like a
(25:41):
force if it's not really? All right? Um, so it
may or may not exist, this graviton, and it may
or may not totally change our our our understanding of
the whole universe. And so then I think that brings
us to the question of how are we gonna result this?
How are we going to find this thing or not
find it or conclude that it doesn't exist. So let's
get into that first. Let's take a quick break. All right,
(26:14):
we're talking about the graviton, and we're saying that it's
it's kind of the minimum little ripple that that maybe
gravity acts through. That if it exists, it means gravity
is like the other forces. And if it doesn't exist,
it means gravity is something totally different and special. So
how are how are we going to find out what
the answer is? Saying, Well, there's two basic approaches. One
(26:35):
is two sort of look for evidence of it happening already, right,
And we do this in astrophysics all the time. We
just say, well, let's just look at into the universe
and find something crazy which reveals to us the truth.
Like when we're studying dark matter, and we saw the
collisions of two galactic clusters that showed us how dark
matter gets separated from normal matter. So in this case,
(26:57):
we'd be looking for like really huge gravity tational waves.
So we've already seen gravitational waves, right, Those are evidence
of the wiggling of a gravitational field when like black
holes collide or whatever. And it's hard to see them, right,
It's really difficult to see them because they're really faint,
and so it's even harder to see whether they're made
of little bits or not. Right, Like, we can just
(27:19):
barely see them, so it's hard to tell if they're
what they're made out of. So what you need to
do is spot like a really mondo gravitational wave, one
that was big enough that you could sort of zoom
in on it and see what is made out of
something really big, like a like a mega tron. I
think I call it a gravitron. Nader or something, so
(27:44):
so you need to find It's so the gravitas they
exists are so small and weak you can't just like
measure them with your finger, right, You're saying, we need
to find something really crazy happening in the universe where
that's producing so many of these and such an amount
that then you can notice them. Yeah exactly. That's one strategy.
The other strategy is to try to make them here
(28:05):
on Earth. And you know the go to place for
making crazy stuff here on Earth, of course, is the
particle collider. Like you want to make something new, something
you're not sure as possible, just keep smashing particles together
and eventually it will come out. And so you're saying,
one way to maybe study graviton is to make gravitons. Yeah, exactly.
And that's the magic of a particle collider is you
(28:27):
throw stuff together and if something can exist, then you
will see it. And so if we smash protons together
often enough, and gravitons are a thing, that eventually those
two protons one a trillion or one or the quadrillion
collisions will turn into a graviton, and that graviton will
then turn into something else that we can see. Hold
(28:47):
on a second, Daniel, here, you're saying that at the
particle collider, you're taking protons, smashing them together and then
transforming them into gravitons. We want to, we're open to
that would be come true. So far, no, so so
a graviton is a transformer if you find it's what
I'm saying, I totally walked into that. It's exactly. Or
(29:09):
the particle collider is the transformer because it transforms protons
into other kinds of stuff. But you know there's a
huge difference. They're transformer when it changes. It's all the
same stuff, just rearranged in a different shape. Right. The
dinosaur is actually the robot, just with the head where
the tail is or whatever. But in this case, we're
not doing that or not. We're not rearranging what's inside
(29:30):
the proton into a different shape to make a graviton.
The proton and nilin it turns into nothing. It turns
into raw energy, which that can then be turned into
something new. That's how exactly you explore the universe by
turning this raw energy into any of the stuff that
he can turn into. So it's more like alchemy than transformation.
(29:51):
That's uh, and those are totally different for sure. Yeah, exactly.
If gravitons exist, then the idea is we could make
them by colliding proton together. Eventually, one out of a
jillion times we would make them, and then we would
see them turn into other particles like a pair of electrons. Right. Essentially,
a graviton would look sort of like another version of
the photon. Would you be able to see it though?
(30:13):
Wouldn't it be so weak and small that you be
very very very very difficult to see. Well, that's the
cool thing about the collider, right, I feel like I'm
a collider evangelist today, is that things that are really
weak that are hard to see just turned into things
that are really rare at the collider. And so the
more collisions you make, the more you can see rare
stuff like yeah, it's weak, which means every time a
(30:35):
proton collides, you've got to roll a like trillion sided
die to figure out what's going to happen, and only
one of those sides says a graviton is made. But
that's cool. If you roll the die at trillion times
a day, then you're probably gonna get a graviton a day,
So it sort of sounds like you're basically looking for
effects that you can point to and say, hey, that
means that there's a graviton somewhere in there, like when
(30:58):
two black holes collide or when you smash these protons together. Exactly.
That's what we do with colliders. We look for unique
signatures of new particles, something that says, oh, this has
to be a new particle. It's very likely to be
a new particle that can't be explained in any other way.
And so we have theories of how gravitons would look
in our detectors, and so we're looking for them. Um.
(31:18):
So far, we haven't found a hint of gravitons and
our detectors, um, which just means that you know, they're
basically smaller than we can see. Um, so we could
just keep looking. What you said, you haven't seen a
hint of them, so like zero zero nothing. Yeah, exactly.
What we've seen so far is totally consistent with Einstein's
theory of general relativity. Well, what do you think is
(31:40):
more more likely, just in your personal opinion, do you
think the graviton exists or do you think maybe it doesn't.
End Gravity is a very special kind of force. I
think that we're going to figure out that everything is
quantum mechanical. I think the quantum mechanics is just so
fundamental to everything we've seen in the universe except for
this one thing that it seems more likely to me
(32:01):
that we just haven't understood that one last thing yet.
Um that it's you know, it's the one thing that's
has that's left over that hasn't been translated yet into
modern theories of physics. Um. So that's my suspicion that
everything is quantum mechanical, because if, if, if most things
are quantum mechanical, it's hard to imagine how you can't
have everything quantum mechanical, you know, like where's the interface
(32:23):
between the quantum mechanical stuff and then non quantum mechanical stuff.
They have to interact and so they have to both
be quantum mechanical to sort of talk to each other. Yeah,
so you're really hoping that it's true, because then that
would be like the gravytan on your mash potatoes. No, no,
I suspect it's true. I hope it's not, because it
would be a huge shock if it wasn't right. And
(32:44):
that's the best case scenario for science is learning something
which is a deep shock to like the fundamental community
to say, like what that's impossible. That makes us rethink everything. Awesome,
that's what science is about, right, not like, yeah, we're
pretty sure it's quantum mechanical and turns out it is
check as much less exciting, even if I think that's
most likely the reality. Well that's my personal philosophy. Aim high,
(33:09):
but have low expectations. Well, I hope that's working for you. Well,
I have expectations, so it doesn't. I won't be disappointed
no matter how the gravy tastes. You're happy with it
if it's made out of big lumps or tiny little gravitons.
All right, So I think that we covered what a
graviton is, right, Daniel, Yeah, how would you summarize it?
I would say it's like gravy with fore and on
(33:31):
top of the transformer and then mixed together with some alchemy.
That's that's what I thought out of this, and then
take two of those and smash them together. No, I
think I think it's the idea that, um, you know,
gravity as a force has to transmit in some way, right, like, um,
you know, it's just it's not like an instantaneous thing,
(33:51):
like a magical thing, so it has to transmit in
some way and and possibly in a minimum way. And
that's kind of what this graviton is, right, the idea
that something is transmitting the force and prep you are
officially a quantum physicist. All right, Well, we hope you
enjoyed that. This is one of my favorite topics in
physics because it's theoretical, it's experimental, it's experimentally theoretical, it's
(34:12):
theoretically experimental. It's crazy, it's fascinating, and we don't know
what the answer is. But someday humans will somedays somebody
will know. Is gravity quantum mechanical or is it special? Great?
Thanks for joining us, See you next time. Before you
(34:33):
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 More podcast from
(34:56):
my heart Radio, visit the I heart Radio app, Apple podcasts,
or wherever you listen to your favorite shows. H
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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