What is a particle?

Daniel and Kelly try to get an solid mental picture of this particularly slippery concept

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Episode Transcript

Speaker 1 (00:06):
What is everything made out of? That seems like a
simple question, and it also seems like a reasonable question.
I'd like to know what I'm made out of, what
my food is made out of, what kittens are made
out of, what lava is made out of. It's also
an ancient question, I think, one that people have been
asking since people have been asking any questions. The Greeks,

(00:26):
famous for asking questions in their sexy robes, thought that
everything was made of earth, air, water, and fire. And
modern science, of course, has made a lot of progress
here and uncovered some pretty weird and kind of shocking
news about what everything is made out of. What seems
like smooth and continuous matter is actually made up of

(00:47):
tiny little bits that are woven together into some extremely
fine mesh. And we are all made of the same
basic bits, some together to make me or you, or
kittens or lava. The world is of particles. But our
curiosity doesn't just end because we have that answer. We
want to know what are these basic bits? How do

(01:08):
we think about them? What mental pictures should we have
in our mind? Are they tiny dots of stuff or
rippling waves or some other concept that's too alien to
even imagine. And what does it tell us about the
universe that these are its basic building blocks?

Speaker 2 (01:23):
Or are they? So?

Speaker 1 (01:25):
Today, on Daniel and Kelly's Extraordinary Universe, we'll be tackling
the basic yet confusing, the simple yet deep, the important
but impossible question what is a particle?

Speaker 3 (01:49):
Welcome to Daniel and Kelly's Extraordinary Universe. I'm Kelly Wiener Smith.
I'm a parasitologist and I'm particularly excited to be here today.
But it might have been really cute if I had
been able to pull it off, but I didn't.

Speaker 2 (02:04):
Hi, I'm Daniel.

Speaker 1 (02:05):
I'm a particle physicist, which means I probably should know
what a particle is.

Speaker 3 (02:11):
Well, we've got the right expert on the show today.
So Daniel, here's what I'm wondering. So you've told me
that you go to CERN in Switzerland to do your research.
Why doesn't the United States have the biggest particle collider?

Speaker 1 (02:24):
Oh my gosh. Why you are putting your foot in
a sensitive spot right there. You know, for many years
it was a race between the Europeans and the Americans.
So before CERN had the most powerful collider.

Speaker 2 (02:36):
We had one.

Speaker 1 (02:36):
It was outside of Chicago at Fermi Lab. It's called
the Tevatron. I did my PhD there. I had one
child born near that collider, and then my next child
born near Cerns. You know, not a kid at each collider.

Speaker 3 (02:47):
Basically, wait, one of your kids was born abroad?

Speaker 1 (02:51):
Yeah, my daughter Hazel was born in Switzerland, very close
to cern That's cool.

Speaker 3 (02:55):
Did you have to not pay because you were in
Europe and they just do healthcare there or what was
that like?

Speaker 2 (03:01):
No?

Speaker 1 (03:01):
Actually they told us that when we showed up for
the delivery, we had to bring fifty thousand Swiss fronc
in cash if we didn't have local insurance.

Speaker 3 (03:10):
WHOA.

Speaker 2 (03:11):
So yeah, that was going to be an issue.

Speaker 1 (03:13):
But then we discovered this a law in Switzerland that
if you're working there, which my wife was, they have
to insure you. So even though she had all sorts
of crazy pre existing conditions, we could buy insurance for
like one hundred franc and then we didn't have to
pay for anything. So it was amazing.

Speaker 3 (03:28):
Actually nice, Okay, that's good.

Speaker 1 (03:30):
And the insurance company even offered to retroactively cover a
bunch of appointments to where we hadn't yet had insurance.
It was very different experience than American insurance.

Speaker 3 (03:39):
Yeah, that's incredible. I'm going to get depressed if we
stay on this topic too long. Let's go back to
particle colliders. Okay, so you have had each of your
children near very large particle colliders. Why isn't the biggest
one in the US.

Speaker 1 (03:50):
Well, they planned to build the biggest one in the US,
the Superconducting super Collider in Waxahachie, Texas, and they started
building it, and they spend billions of dollars digging a hole.

Speaker 2 (04:00):
But then the director of CERN.

Speaker 1 (04:02):
At the time came and testified before Congress saying it
was a big waste of money because CERN was building
one that was going to be bigger and better and
they should just cancel it. And Congress, for all sorts
of complicated political reasons, listen to him and canceled the
American Superconnecting super Collider. And since then the lead has
been in Europe and probably will for a while. And

(04:22):
the US particle physics communities mostly focused on things like
neutrinos and stuff like that. So these days, if you
want to do cutting edge, high energy particle physics at colliders,
you got to go to Switzerland, which, hey, it's not
too bad.

Speaker 2 (04:35):
The chocolate's amazing, no doubt.

Speaker 3 (04:37):
You know what. Actually, I'm gonna go out on a
limb here and say I'm not a huge fantas with chocolate.

Speaker 2 (04:41):
Yeah, I know you prefer Belgian I do.

Speaker 3 (04:44):
Yeah, there I said it. So every once in a
while I'll hear about like astronomy students who want to
get time on a telescope, but the telescope's all booked
up and it takes forever. Does cern have enough time
for everyone? So like, when that guy came to the
US and tanked our program, did he know he was
going to have enough time time for all of our
scientists to come over and do their work.

Speaker 1 (05:03):
Yeah, that's a great question, And people often ask me
about that, like what's it like to set up your
experiment at the collider? But the reality is very different.
Telescopes and colliders don't work the same way. A telescope
you have to point at the thing you want to
look at. So you write a proposal to say, let's
point our amazing telescope at this one star I want
to study, and then it's not pointing at any other stars.

Speaker 2 (05:22):
But a particle collider is very general.

Speaker 1 (05:24):
It always just does the same thing smashes the particles
together and you take pictures of it, and then afterwards
you analyze it. So everybody who uses the collider uses
the same data. They're just looking for different kinds of particles.
We don't have to point the collider at certain things.
We don't swap out what we're using to take pictures.
Every few years we turn the thing off, revamp it,

(05:44):
build a new detector that's better, faster, higher resolution or whatever,
and then we make it as general as possible so
everybody can use it so you don't have to swap
it out every day or every experiment. Everybody uses the
same data set, which makes it kind of crazy because
everybody's looking for discoveries in the set SA data set
at the same time, So you could get scooped by
any of your thousands of colleagues Yanks.

Speaker 3 (06:06):
So do you actually need to be there in person
or if it's just data, they can make that available
anywhere right.

Speaker 1 (06:13):
CERN has long been at the forefront of the Internet.
We invented the web at CERN, for example, and we
have excellent cloud computing and so we transfer that data
all around the world. We've collaborated from Japan to Singapore
to South Africa, to the northern tip of Canada, all
over the world. People analyze this data. Absolutely, you don't
have to go. I go frequently because I have students
there and postdocs are like on site building stuff and

(06:35):
helping keep it run. But technically you don't have to
to look at the data.

Speaker 3 (06:39):
Cool. I mean, that's good and bad. I feel like
ecologists like we want to study exotic animals, but partly
because we want to go there, And I imagine it's
sort of the same with cern, like it'd be nice
to go to Switzerland. But I guess the more important
thing is answering the question.

Speaker 1 (06:51):
It is nice to go to Switzerland, but then again,
it's also nice to be able to do science without
having thousands of dollars to go to Switzerland, which means
smaller groups and not such institutions, for example, could also participate.
So it makes it a little bit more democratic, you know.

Speaker 3 (07:05):
Nice. That's awesome. Okay, So the whole point of having
a large particle collider is so that you can figure
out what those particles are made of, Is that right?

Speaker 1 (07:14):
The whole point of having a particle collider is that
you can say you're smashing particles together and nearly the
speed of light, which sounds pretty awesome at parties.

Speaker 3 (07:21):
It does, yeah, kind of like jousting for particles.

Speaker 2 (07:24):
Yeah.

Speaker 1 (07:25):
Well, particle colliders, I think, sort of have two different purposes.
One is like, hey, let's take stuff and see what's
inside it. Let's start with something familiar, you know, like
the proton, and smash it open and see what it's
made out of. And that's a continuation of like a
long glorious tradition of taking the stuff around us a
part to understand what it's made out of. You know,
I'm made of molecules, which are made of atoms which

(07:46):
have a nucleus and electron, and the nucleus is made
of protons. Let's go inside the proton. So that's definitely worthwhile.

Speaker 2 (07:53):
And we do that.

Speaker 1 (07:54):
But colliders can actually do something else, even more powerful,
which kind of sounds like magic, which is that they
can convert the mass of those protons into energy and
then back into mass, and so what can come out
of the collision is not just a rearrangement of what
went in. It's not like chemistry where you're like this
hydrogen moved from this atom to over there, and now

(08:14):
you have a different kind of compound. You can annihilate
these things, and then you basically have like a budget
to make anything. And the stuff that comes out of
the collision doesn't just have to be like a refashioned,
rearranged version of what went in. You can have entirely
new matter. It really is alchemy. So like protons go in,
you have this intermediate state of frothing energy, and then

(08:36):
you can make whatever the universe can make, dark matter, muons,
all sorts of other stuff. You're not just rearranging the protons.

Speaker 3 (08:44):
There's got to be some rules right for what you
can make.

Speaker 1 (08:49):
Yes, exactly, that's the whole premise of particle physics. There
are rules, there are patterns. Quantum mechanics tells us what's
likely to happen in certain collisions. We look at those patterns,
we notice, oh, this typically happens, typically shoots out at
those angles.

Speaker 2 (09:01):
What are the rules that control this?

Speaker 1 (09:03):
Absolutely there are rules, but fundamentally it's random. Right, Like
you do the same collision twice, you get two different answers.
Because it's quantum mechanical, it's not determined by the initial conditions.
So it's really a very powerful way to explore the
universe because you don't have to know what's out there
in order to discover it. You smash protons together often enough,

(09:24):
eventually everything the universe can do, it will do, and
you get to take pictures of it.

Speaker 3 (09:29):
Wow.

Speaker 1 (09:30):
It's like, imagine if you could build a box and
every kind of creature that could exist on Earth would
randomly cycle through that box. You could just sit there
and watch and be like, oh, wow, I didn't know
that existed. Oh look at those things.

Speaker 2 (09:42):
What are those? You know?

Speaker 1 (09:44):
That would be pretty powerful. That's basically what we can
do with particle physics.

Speaker 3 (09:47):
Now you have my attention. Although that box, I guess,
could mostly be showing me like different species of bacteria,
which would be a bomber. You could show me different
speceis of bugs, that would be great.

Speaker 1 (09:55):
Yeah, it'd be mostly beetles. You're like, wow, it's basically
a beetle box.

Speaker 2 (09:58):
Right.

Speaker 3 (10:00):
So there is that famous saying that like God is
inordinately fond of beetles, because there's this thought that beetles
are the most common species group on the planet, but
actually quite often those beetles are infected by more than
one species of hymenopter and wasp, and so we think
there might actually be more wasp species on the planet

(10:20):
than there are beetles based on that observation.

Speaker 1 (10:23):
And probably those wasps are infected by viruses, so they're
more viruses than wasps. Yes, and those viruses are made
of particles, and boom a boom, we're back to the
topic of the episode.

Speaker 3 (10:34):
Well, what makes up a particle, Daniel exactly?

Speaker 1 (10:37):
So we smash particles together, we look at what's inside them,
we annihilate them to make new kinds of particles. We
have this idea that particles are what everything is made
out of. But I struggle, still after decades in this field,
to understand this basic question what is a particle?

Speaker 2 (10:54):
So I really want to explain to.

Speaker 1 (10:55):
People what we do know and what we still don't
know about this very basic concept that everybody talks about
all the time.

Speaker 3 (11:01):
Well, first, let's hear what our listeners think. And if
you would like to be a listener who tells us
what you think, send us an email at questions at
Daniel and Kelly dot org and we will get you
in the loop and send you a question from time
to time and you can send us your answers. So
let's see hear how folks answer the question what is
a particle?

Speaker 2 (11:20):
A particle is a thing that interacts with other things.

Speaker 1 (11:24):
A particle is really just an excitation in a field.

Speaker 2 (11:29):
A particle is a defined portion of something, something that
is infinitesanly small to us.

Speaker 1 (11:39):
It's the smallest unit of energy or mass.

Speaker 3 (11:43):
I think that particles are the excitement of different friends,
spatial spots, and interaction.

Speaker 2 (11:49):
A particle could be very small vibrating field. A mass
or non mess object.

Speaker 1 (11:54):
Exists within what we would perceive as matter.

Speaker 4 (11:59):
A particle is a sub microscopic kernel of energy and
or matter. A particle is an excitation of a field.
I do know that particles aren't just tiny bits of matter.
I've heard that there fields, or strings, or some other

(12:22):
impossible to understand little bits of the universe.

Speaker 2 (12:27):
Particle is a ripple and a quantum field. Particle is
the name we give to the smallest discrete, quantum little
bits that we know of and haven't been able to
break up.

Speaker 3 (12:41):
Further yet, an expression of a field where the chances
of that occurrence happening is the greatest. There. The more
think about, the bigger this rabbit warren is going.

Speaker 1 (12:54):
I think these answers perfectly encapsulate this episode. I mean, really,
it's an excellent snapshot because a lot of what people
have said in here is correct. But also there's a
huge list of conflicting answers, right, you know, is it
the smallest bit of stuff? Is it just something in
space time? Is it actually an excitation of a field?
You know, there's so many conflicting concepts for what a particle.

Speaker 3 (13:14):
Is, and is this one of those topics where at
the end the answer is going to be we really
have no idea, could be all of these things? Or
is this a topic we're at the end. We're going
to have a pretty clear answer.

Speaker 2 (13:27):
At the end.

Speaker 1 (13:28):
We're going to have a pretty clear answer, but not
at the end of this episode, at the end of
this journey, which might be in ten or one hundred
years unfortunately. Okay, I mean we're going to get somewhere.
Today we have a pretty crisp clear view of what
a particle is mathematically, but we also know why that's
not really satisfactory, and there's lots of big open questions
about what that really means. So it's not like all

(13:50):
particle physics is a scam because we don't know what
a particle is. We have a working definition, but we
also know that it's incomplete, just like most of science.

Speaker 3 (13:57):
Right, Oh yeah, amen, All right, well, so let's start
with the historical perspective. Bring me back to the beginning.
When did we start thinking about this question?

Speaker 1 (14:04):
Yeah, I think it's important to trace the origin of
this historically because it still shapes how we think about
the universe. And you know, whenever you ask a big
question about science, you got to think about like what
kind of answer you're looking for.

Speaker 2 (14:17):
And in science, even though.

Speaker 1 (14:18):
We try to be like mathematical and open minded and
let the data tell us what the universe is saying,
we still need to understand that data. We still need
to interpret it. We still need to cogitate on it
in a way that makes sense to us. And we're
sort of limited in our mental intuitive language. We can't
really grapple with things that we've never experienced, that are

(14:40):
completely alien to us. We tend to translate the unfamiliar
into the familiar.

Speaker 4 (14:46):
You know.

Speaker 1 (14:46):
My favorite example of this is like what happens when
you drink a wine or you taste a new fruit
and you're like, oh, this fruit tastes kind of like
a cherry and kind of like an apricot and whatever,
and a little bit like a kiwi. You're explaining something
new in terms of something you already know, and that
makes a lot of sense also what we do in science,
and so it's important like dig into like what are
the sort of basic mental building blocks we're using to

(15:07):
understand this stuff.

Speaker 3 (15:08):
I think one of my favorite examples of that is
the brain being compared to whatever technology is hot and
new at the time. You know, like your brain is
like a clock, your brain is like a computer. And
some of those analogies work in some ways, but you know,
having an analogy like that sometimes limits the way you
actually attack a problem.

Speaker 1 (15:23):
Yeah, but it also is what allows you to understand it, right,
So in the end, it's sort of how we understand everything. Yeah,
And that's why it's useful to go back to like
fifth century BC and talk about Democratus and his buddy Lucepis,
because these folks were thinking about, hey, what is the
universe made out of? And they came up with this concept,
or they're credited with this concept of what seems like

(15:46):
smooth and continuous matter, you know, water, seems smooth and continuous.
Air seems smooth is actually made of tiny little bits
of stuff. This is a big idea, right, This is
a huge concept. It is like pulling back the veil
on the world and saying the world isn't the way
that it seems. It's actually quite different. You know, it
has like a resolution. These days, we're kind of familiar

(16:07):
with this because you're used to things like, Hey, I
look at my TV screen. It looks like I'm just
looking at a picture, but I know that if I
put my eyeball closed to the screen, I'll see pixels.
This is basically saying the whole world, all matter is
actually pixelated. It's built out of little bits instead of
smooth and continuous.

Speaker 3 (16:24):
Did they have any thoughts about what the little bits
were like, like do you get different bits in the
sand and different bits in your skin? Or how fine
grained was this idea?

Speaker 2 (16:35):
Oh my god?

Speaker 1 (16:36):
They had hilarious ideas about what the little bits were.
They thought that everything was made up a little bit
of stuff, but that stuff had different shapes, and you know,
they were right on the spirit of it that they thought,
like the properties of the shape determined how we experienced
it and its property. But for example, they thought that
something's tasted sour because it was made of little sharp

(16:56):
needle shaped atoms that like stabbed your tongue when you
ate it.

Speaker 3 (17:00):
This is going to be so condescending, but that's such
a cute idea.

Speaker 2 (17:03):
It is so cute, I know.

Speaker 1 (17:05):
And they thought that things that were white were white
because they were made of very smooth atoms. And they
thought that your soul was made of atoms, and that
those atoms were particularly fine grained. They were right in
the spirit in that the behavior and the structure of
the atom really does determine, like hey, what is shiny
and what conducts electricity and what's liquid at room temperature.

(17:27):
That's all true. They were just wrong on the details.
But you know, they couldn't see atoms. They were just imagining.
And I'm really impressed by this. I'm impressed by the
courage to imagine that the universe is so fundamentally different
from the way it seems, because that's really the scientific spirit, right, Yeah, totally.

Speaker 3 (17:44):
Okay, So we've got Democritus and his buddy what was
the buddy's.

Speaker 1 (17:48):
Name mispronounced as Lacoupiskopis, But I don't know the correct pronunciation.

Speaker 3 (17:53):
I hadn't heard of that person before. So you got
the two of them, and they're proposing that everything is
made of small bits of stuff. How long before we
get some clarity on the fact that sour isn't just
sharp little bits of stuff.

Speaker 1 (18:07):
Yeah, so they're credited with this idea, probably came up
earlier because remember, we give people credit because we have
a written.

Speaker 2 (18:14):
Record of it.

Speaker 1 (18:15):
We have like a tiny fraction of everything the Greeks wrote,
though very excitingly, they're now scanning burnt scrolls from an
ancient Greek library. We're going to like double the amount
of Greek writing.

Speaker 2 (18:24):
We have very soon.

Speaker 1 (18:26):
But also, you know, we just don't have writing from
other civilizations. What do the Etruscans think ancient Chinese writing? So,
you know, people give the Greeks a lot of credit,
but we should remember like other people thought about this
stuff too.

Speaker 3 (18:36):
Ain't that always the way?

Speaker 2 (18:37):
It's always the way, I know.

Speaker 1 (18:39):
And they use the word adam because atomos in Greek
means indivisible, So that's where that comes from. And this
is the origin of this idea that you know, smooth
stuff is actually made of little bits and that still
guides our mental picture. When I think particle, I still
think tiny little dot of stuff, like a little spinning
ball or a grain of sand.

Speaker 2 (18:59):
That's what it means to me.

Speaker 1 (19:01):
Like it's particular, Like if you say something is particulate, right,
you mean it's made of these little bits. And so
the words are powerful because they guide our mental images.
But it wasn't for a couple of thousand years that
we had really more information. I mean it was chemists
like Dalton who were doing experiments on chemical reactions and discovering,
you know, laws of ratios and proportions and the things

(19:24):
were divisible by integers. That really give us a clue that, oh,
there were like units of stuff going into these equations
that you really needed two to one hydrogen to oxygen
to make a certain amount of water. It gives you
a clue that it really has just clicked together out
of these tiny little bits. So that was a really
important clue. But it wasn't until the late eighteen hundreds
that we really had the discovery of anything that we

(19:46):
would today call a particle.

Speaker 3 (19:49):
And is that because it's so tiny, it probably depends
on having the right technology to be able to address
that and so did we just have to wait until
the late eighteen hundreds because that's when we finally got
the technology where we could start making a dent.

Speaker 2 (20:02):
Yeah. Absolutely.

Speaker 1 (20:03):
And in the great tradition of particle physics, we didn't
invent the technology that we used to make these discoveries.

Speaker 2 (20:09):
We borrowed it. In this case, we borrowed it from
the circus.

Speaker 3 (20:12):
From the circus, yes, exactly. All Right, we're going to
take a break, and when we come back, you're going
to tell me about how the circus allowed us to
understand the electron. All right, and we're back, and today

(20:40):
we're talking about the freak show that is particles, and
Daniel's gonna tell us about how we were able to
understand the electron from technology developed for the circus mm HM.

Speaker 1 (20:52):
Back in the mid eighteen hundreds, there were circuses, and
there were these side shows, and you know, you had
bearded ladies or conjoined twins or whatever freak show you
wanted to see, but also you had people with weird gizmos,
and in particular, somebody invented basically the cathode ray tube,
but a cathoid ratube back then was actually called a
Crooks tube. And basically you have a glass and you
put electricity on one side, electricity on the other side,

(21:15):
and we now know what happens is that electrons boil
off of one and fly through it.

Speaker 2 (21:20):
And hit the other.

Speaker 1 (21:21):
But if you left a little bit of gas in
that tube, then the electrons would hit that gas and
gas would glow. People were making these tubes because they
glowed in this eerie way and that was pretty cool.
And you know, back in the eighteen hundreds, this was
a magical thing to see that somebody could build this
thing and it would glow green, it would glow red
or whatever. And so these Crooks tubes were very popular

(21:43):
on side shows. And then later scientists were like, what's
going on here, Let's see if we can understand what's
going on. And JJ Thompson in the late eighteen hundreds
used it to discover the electron.

Speaker 3 (21:54):
How do you go from ohnit that tube lights up
to and that's because of electrons.

Speaker 1 (22:00):
Yeah, So JJ Thompson was trying to understand what is
lighting up here. And they already called these things cathode
rays because they could see paths, like definitely, there's a
line of stuff moving through them. And they were like,
what are these rays? Is it made of something? A
lot of people tried to understand this and failed, But
he had like the best vacuum, so the best control
of this experiment, and he did it the most systematically.

(22:22):
What he did was he put these tubes under electric
fields and he was like, hmm, can I bend these rays?
And then he tried with magnetic fields, like, oh, can
I bend the rays this way and that way? And
he tried with combinations of them. And so we had
an understanding of electromagnetism back then. We understood that electric
fields whole things that have charge, and magnetic fields can
bend them. So from this he determined, oh, these cathode

(22:44):
rays are little bits of charge. There's charge flowing here
because I can bend it with fields, and so that
was really fascinating. And then he very carefully bounced the
two fields and he was able to measure the mass
of the thing, and that right there is the origin
of this sort of concept of a particle. He was like, oh,
these rays are made of tiny little bits of stuff

(23:05):
that have a charge and a mass. And what he's
doing conceptually there is very important. He's saying there's a
point in space, and I'm going to put two labels
on it. I'm gonna say it has a charge and
has a mass, and those two things cannot be separated.
He tried to separate the mass and the charge and
he couldn't. So he's like, now in his mind, he
has these little dots that are moving through space and
he's putting these mental labels on them. And that's really

(23:27):
the origin of the modern concept of a particle.

Speaker 3 (23:30):
Okay, So I'm imagining being in his lab He's got
this ray, he's got a magnet on one side, and
he does the magic, and he's got that line. Is
it like a bolt of lightning? Like does it go
from one side to another and you can see all
of it? And if so, how does he make the
jump from there's a line that lights up and bends
towards the magnet two, And that line is made up

(23:51):
of lots of little tiny things that come to be
called electrons, You know what I mean.

Speaker 1 (23:56):
Yes, So what you should be imagining is sort of
like what a fluorescent life. Well it looks like now,
it's like long and thin and filled with glowing gas, right,
except there were like thinner lines. So these were very
clearly rays. And you're right that he measured that there's
sort of a flow of charge. Right, So there was
a screen on one end and you could see these
glowing dots landing. But he also measured the mass. That's

(24:18):
what told him that this was made of little bits
because he could measure actually their charge to mass ratio.
He couldn't measure the mass itself, but he measured the
charge to mass ratio by seeing how much they were
deflected by the magnetic fields.

Speaker 2 (24:31):
That's the thing that.

Speaker 1 (24:31):
Gave him the clue that it was made of little bits,
not just some continuous stream, because he could identify a
charge to mass ratio for these bits. And he almost
sent the world down a crazy path where my job
title would be different because he didn't call this thing
a particle, he didn't call it an electron. He used
the word corpuscule. He thought that was a really cool

(24:52):
name for this thing that he help. To me, it
sounds like especially explosive kind of Yeah.

Speaker 3 (25:00):
Yeah, so you were almost a corpuscoologist.

Speaker 1 (25:08):
Or a corpuscular physicist. Fortunately, the person who discovers the
thing doesn't always get to name it, and later on
people adopted the name electron suggested by Fitzgerald and Lorentz
and other folks, and so fortunately the word corpuscular didn't
hang on. But that was really the seminal experiment where
people discovered, okay, the world has made the little bits,

(25:30):
and we can put labels on them. And these days
we have so many labels for particles. We put spin
on them, we put charge. Of course, we put other
kinds of charge. Every particle has a charge for electromagnetism,
as a charge for the weak force, a charge for
the strong force. It has a mass. This is really
part of the concept of a particle is a little
dot in space with labels that we put on it.

Speaker 3 (25:52):
And it sounds like it gets complicated pretty quick. So
let's back up a little bit. So we've got mass
in charge. What is our next historical advancement?

Speaker 1 (26:02):
Well, next came Rutherford because people were wondering, all right,
so these things exist, these corpus s gules, or these
electrons as we they to call them. But how do
you use that to make up the world. It's sort
of like the twofold question we were talking about before.
One thing you can do is try to answer, like,
what is everything around us made out of by taking
it apart. The other is just to ask what can

(26:22):
the universe do? Like, not necessarily, how am I built
out of the universe, but what is the universe capable of?
Sort of holistically, And so Thompson discovered, oh, the universe
can make electrons. People were wondering, Okay, are those electrons part.

Speaker 2 (26:35):
Of who we are?

Speaker 1 (26:37):
And you know, they were speculating, we think electrons are
probably inside the atom. But nobody knew yet what the
atom structure was. We knew that we had chemicals and
we had these different atoms and periodic table the elements
was a thing, but nobody understood how the atom itself
was built. And we suspected electrons were in there, but
we didn't understand, like, well, what's balancing that charge? And
so Thompson proposed that, like, well, we have electrons because

(27:00):
I discovered them, and so they must be the building
block of everything, and they're embedded in like a jelly,
like a positive jelly that balances the charge.

Speaker 2 (27:08):
That was sort of his idea.

Speaker 1 (27:09):
But then Rutherford came along and said, well, let's see,
and he took a sheet of gold foil and he
shot radiation at it, and he wanted to understand, like,
what is that positive stuff made out of And if
that positive stuff was like spread out like jelly, then
he would expect that his particle would mostly just slop
through it. But what he saw was that most of

(27:30):
the time they just shoot right through the foil, but
occasionally they bounced right back. What he concluded from that
was that the positive charges weren't spread out evenly. They
were clustered into these little hard dots. So most of
the time the radiation missed it, sometimes they bounced right back.
That gives us the more modern picture of the atom
as a positive nucleus surrounded by electrons.

Speaker 3 (27:51):
Okay, so if we are still trying to think of
this as a jelly, then we should be picturing like
that strawberry jelly that has seeds in it, and those
seeds are like the nucleus that the electron was bouncing
off of. Is that right?

Speaker 2 (28:03):
M hmm exactly.

Speaker 1 (28:04):
And so now we have like electrons, and we also
have the nucleus, which later on we discover is made
out of protons and neutrons. And so you were starting
to build up our catalog of particles to try to
understand like what is the world made out of? What
are these particles? And at this point the concept of
a particle is still it's a dot in space that
we could put labels on, and one of those labels

(28:26):
is mass. But then that was all up ended when
we discovered the next particle, which is the photon.

Speaker 3 (28:32):
Why does it always get more complicated?

Speaker 2 (28:34):
I know?

Speaker 1 (28:35):
Photons mess everything up, right, my goodness. So around the
turn of the century, Einstein was thinking about what happens
when you shine light on metal, very bright beam of
light on metal. What happens is electrons boil off. This
is something people had seen but not really understood because
they were confusing results about what happened when you made
the beam brighter. People expected that if you make the

(28:56):
beam brighter, which if light is a wave, mean that
the em fields are oscillating with larger amplitude, so more energy.
Then they thought that electrons should get kicked off with
more energy. But instead what they saw was electrons kicked
off with the.

Speaker 2 (29:11):
Same energy, but more of them.

Speaker 1 (29:13):
So instead of having faster moving electrons, you have more
electrons at all the same speed. And it was Einstein
who figured out what that meant. What it means is
that the light you're shining at the metal is not
a continuous beam, perfectly smooth the way Maxwell imagined, but
made of chunks made of bits called photons. And what
was happening is that each electron can only absorb one

(29:37):
like the electron absorbs a photon or it doesn't.

Speaker 2 (29:39):
If it absorbs a photon.

Speaker 1 (29:40):
It gets kicked off, and it always has that photon's energy.
You can't eat two photons or ten photons, and so
when you make the being brighter, you're shooting more photons.
More electrons get to eat a photon. But because it's
based out of these chunks, it's not smooth and continuous.
It's basically a one on one interaction.

Speaker 3 (29:58):
You said that was Einstein who helps figure outright, So
that wasn't that long ago one hundred years. Yeah, we
went from like nothing to amazing detail in the last
hundred years.

Speaker 4 (30:06):
I know.

Speaker 1 (30:07):
It's really incredible what we've understood. And this is a
huge advance because now we're like, oh wow, light is
also made of little mini servings. Right, there's a minimum
amount of light. Like you take a flashlight and you
start to turn it down and down and down and down.
You can't have it be arbitrarily dim like this one
setting where it's dark, completely dark, but then there's a

(30:27):
minimum brightness. You can't shoot half a photon out of
a flashlight or one and a half photons. It's quantized,
you know, it's not continuous and smooth. But this is
confusing because they were going to call a photon a
particle a minute ago. We set a particle something that
has like mass in charge. Photons don't have mass, So
already your mental conception of like, oh, a particle is

(30:49):
a little bit of stuff, Well, this boton doesn't have
any stuff to it. You know, you can't catch up
to a photon and look at it, you can't hold
it in your hand, and yet we think of it.

Speaker 2 (31:00):
As a particle. So already one hundred years.

Speaker 1 (31:03):
Ago, we have to like back up and broaden our understanding,
like what is a particle if it's not a little
bit of stuff the way Democratis was imagining.

Speaker 3 (31:10):
And doesn't it get even more confusing yet, because then
we decide that photons aren't necessarily particles. Sometimes maybe they're waves.
And at this point you're like, I'm majoring in biology.

Speaker 1 (31:22):
It gets more confusing before it gets more interesting and
more clear. But yes, there's definitely a period of confusion there,
and I do think that's kind of a filter. Some
people hear that and they're like, I need to understand
this and learn more. I'm going to become a physicist.
And some people are like, I'm going to go study eels,
and that's cool because eels can make waves too, you know,
they're pretty.

Speaker 3 (31:41):
Wiggly and electric fields and yeah.

Speaker 2 (31:43):
Yeah, yeah.

Speaker 1 (31:44):
And something you said I want to get back to,
which is like, sometimes they're particles. I mean, a photon
is always a photon. What is a photon? Is it
a particle? Is it a wave?

Speaker 2 (31:54):
Like really, it's neither.

Speaker 1 (31:56):
The way that that new fruit is not a cherry
or an apricot, it's not sometimes because it has hints
of it in your mouth. It's something new and weird.
And a photon has behaviors that we sometimes describe in
a particle way, and behaviors we sometimes describe in.

Speaker 2 (32:09):
A wave like way.

Speaker 1 (32:10):
But it's not choosing now I'm a wave, now I'm
a particle. It's always a photon. It's just that none
of these descriptions perfectly capture what it is the way
that like I can't perfectly describe you. I mean, you're
a mother, you're a partner, you're a podcaster. None of
those things define who you are. You're Kelly, right, and
you're sometimes well described by one of those labels.

Speaker 3 (32:31):
Right, yes, right, So this is another one of those problems,
like brains are like a computer, yes, but not entirely.
And by putting these labels on it, sometimes it helps
you think about it, but also sometimes it makes things
more confusing.

Speaker 1 (32:42):
So let's dig into what it means though, because the
thing people were trying to confront, the thing people were
struggling with is like, yeah, Einstein tells us light is
made out of these little packets, so we should think
of them as like individuals. But also we had all
these experiments showing that lighthead wave like behavior, you know,
it like interferes with itself, diffraction. There's all sorts of
stuff that we only usually attribute to waves, and so

(33:05):
people have this idea in their mind, and they hear
a lot about the particle wave duality that sometimes you
use wave to describe light and sometimes you use particles
to describe light. And later on it got more confusing
because we saw that electrons do this too, like electrons
have wave like behavior. You could take beams of electrons
and they will interfere with themselves as if they are waves.
But you know, electron is like the original og particle.

(33:27):
So what's going on here? And there is definitely a
way to.

Speaker 2 (33:31):
Think about this that's not Sometimes it's a.

Speaker 1 (33:33):
Wave and then it switches suddenly to a particle. It's
the more quantum mechanical way to think about it, which
is rarely like a way to think more clearly about stuff,
but you know, it is the way that we think
about it. And the quantum mechanical way to think about
this without getting heavy into the math, is to say
that what controls where a particle goes is a mathematical
equation that looks like a wave equation.

Speaker 2 (33:55):
We call it the Schrodinger.

Speaker 1 (33:56):
Equation, and it tells us what's likely to happen to
a particle. So an electron enters an experiment, the shorting
equation tells us, oh, is it likely to go left?
Or is it likely to go right? A photon goes
through a slit, the shortening equation tells us is it
likely to go here?

Speaker 2 (34:11):
Is it likely to go there? It's going to land
on a screen.

Speaker 1 (34:14):
The shortening equation tells us what's the probability of something happening,
So it's wave like in that an equation that looks
a lot like other wave equations, the equations we use
to describe oceans and sound and all sorts of wave
like behavior, which is amazingly everywhere in the universe. And
we can have a whole conversation about, like, why does
the universe all seem like waves? There's a wavy equation

(34:35):
that describes where this stuff is likely to go. But
then there's something weird that happens, which is the universe
has to go from here. All the things the photon
could do, and here's the various probabilities of it going
here or there. Then we do the experiment. We want
to know the answer. The universe does this thing where
it picks one. It's like, all, right, of all the possibilities,
I'm going to decide this photon goes over there, and

(34:57):
this other photon is going to go over here, and
this third photon is going to go there. And it's
sort of amazing and it's a process. We fundamentally do
not understand how the universe goes from Here's the list
of probabilities to I'm going to pick one. But this
is what people imagine when they think wave like to
particle like. Wavelike is like when the universe is still
maintaining all the possibilities. Particle like is like I've looked
at it, I've measured it, I see a dot on

(35:19):
the screen. So I'm thinking of it as acting like
a particle because it's here, has the location, and we
think of particles as like it is somewhere. It's a
tiny dot in space with labels. So when we force
the universe to tell us where did that photon go,
we call it being particle like because we put a
location on it.

Speaker 3 (35:37):
Okay, And is this the right way to think about
all particles or do some particles follow this wave function
thing and other particles don't.

Speaker 1 (35:48):
This is the nineteen thirties way to think about all particles.
You can use this to describe photons, you can use
it to describe electrons. You can do use to describe
any particle. This is the Shortener equation, and it works
really really well for individual particles, and these deep fundamental
problems with it still like we don't understand when the
universe goes from here are all your possibilities to actually,
we're going to do this one. People call this the

(36:10):
wave function collapse or quantum collapse, and philosophically it makes
no sense because it doesn't happen when a photon is
measured by a quantum particle. Like a photon can interact
with an electron and maintain all of its possibilities. But
if a photon hits an eyeball you see it here
or you don't see it there, it collapses. And so
really this wave versus particle thing is about maintaining quantum

(36:34):
possibilities or collapsing to one. That's really the core of it,
and that is not something we understand why that happens,
When that happens, If that happens, huge open question in
physics and in philosophy, and what is a particle sort
of sits right at the nexus of that. So we've
mapped this question of like what is a particle to hey,
when do quantum wave functions collapse?

Speaker 2 (36:54):
And do they?

Speaker 1 (36:55):
But that's not a question we have an answer to.
So I'm not sure how helpful it is. But the
modern view of what is a particle is actually a
little bit different from this sort of nineteen thirties concept
of a wave function and the Schrodinger equation.

Speaker 3 (37:09):
Well, let's take a break and then we'll get modern.
So we are up to the nineteen thirties, and now

(37:31):
you are going to tell us about our more modern
understanding of particles.

Speaker 1 (37:36):
Yes, so this idea that particles are these weird quantum
objects and where they go is controlled by a wavy equation.
But sometimes we can make their measurements and force the
universe to tell us where they are in an instant
and they have these properties masked sometimes charge, sometimes spin. Sometimes.
That's sort of an old fashioned view. When we started

(37:58):
dealing with lots and lots of particles discovered, Oh, this
math is kind of clunky. Like if you have ten
particles or one hundred particles, it becomes really awkward to
have a Shorteninger equation for each individual one and try
to bring it together. The math just becomes impossible. And
so people instead of thinking about like one wave function
for each particle, they're like, let's just think about all
the particles as if they're wiggling the same field. So

(38:22):
instead of imagining like an individual person waving their hand,
now imagine like a crowd at a football stadium and
they're doing the wave. So add this thing to your brain,
which is a field. Right, A field in space is
just like a set of numbers. I say, over here
to my left, the field has a value of seven,
and over here to my right field is a value
of three or two or whatever. And there are wavy

(38:45):
equations that determine what is the value of the field.
And so you can have waves in that field. You
can like ripples in that field where like a large
value of the field moves through space from here to there.
And then we think about particles as those ripples in
the field. So we take like individual wave functions, we
try to sort of stitch them together into a single

(39:05):
field and think about all the particles as wiggles in
the same field.

Speaker 3 (39:09):
So what assumptions do you have to make to make
that transition? Do you have to assume that they don't
interact with each other in a way that changes the
behavior of the group?

Speaker 2 (39:20):
Ah, great question.

Speaker 1 (39:22):
You don't have to assume that, because you can have
lots of different kinds of fields. You can have some
fields where the particles don't interact with each other. For example, photons,
photons don't interact with each other. Photons only interact with
particles that have electric charge, like they will be eaten
by an electron or proton can give off a photon.
But photons ignore each other, like they wiggle right past

(39:43):
each other. Two beams of light cross without touching or
bouncing off each other. Other particles do interact with each other,
like gluons. For example, gluons bounce off of other gluons
amid other gluons eat other gluons. It gets very complicated
and messy because gluons talk to each other all the time.
So you don't have to assume that we build that
into each field. So we have a new mathematical framework

(40:04):
that allows us to make different kinds of fields. Some
fields are very simple, they're just numbers, like the Higgs field.
It's just a number in space. Other fields, like the
electromagnetic field. At every point in space, you have an arrow,
you have a direction, you have three numbers.

Speaker 2 (40:19):
Basically.

Speaker 1 (40:20):
So now imagine like a bunch of arrows filling space,
and when a photon is moving through that field, what's
happening is those arrows are growing and shrinking, They're changing direction.
It's oscillations. In these fields that we think about as particles.
But we do have to make one important assumption which
has a lot of consequences, which is that every electron
is basically the same and every photon is basically the

(40:42):
same because they're all part of the same field. It
was a question for a long time, like why does
every electron have exactly the same mass and exactly the
same charge? Why is every photon zero mass? Why are
they all identical?

Speaker 2 (40:55):
Right?

Speaker 1 (40:56):
And the answer is kind of beautiful as well. They're
all wiggles in the same field.

Speaker 2 (41:00):
It's not like the.

Speaker 1 (41:01):
Universe made a bunch of electrons and it was really
good at it, so it was super precise, and the
electron factories like high precision engineering, so they're really you know,
balls on perfect it's because they literally are the same
thing that are just ripples in the same field.

Speaker 3 (41:16):
Well, that's convenient because it's easier to think of it
as a field, right than as a particle.

Speaker 1 (41:21):
Mathematically, it's much easier because if you want to think
about like particles being created, oh, that's just energy going
into the field, whereas in the shirting equation it's like
pretty hard to create a particle and add its wave
function to your calculations, and the same thing with destroying particles.
It's really awkward if you're thinking about it one particle
at a time, and very natural if you're thinking about
it as a group of particles.

Speaker 3 (41:41):
The universe threw us a softball. Thanks universe. Okay, So
when I was in high school, I learned about electrons
and protons and neutrons. I don't remember hearing about quarks.
But you know, since high school, I've learned that protons
are made up of quarks. But I think particles as
being the smallest things that make up everything. And so

(42:04):
if quirks make up protons, does that mean protons aren't
particles or are they both particles but maybe different categories
of particles? What's going on here?

Speaker 1 (42:15):
Oh, that's a great question. So we mostly use these
fields to describe fundamental particles, things that we think are
not made of anything else. So the photon and the electron,
et cetera. Those particles are wiggles and fields that are
just a basic element of space itself.

Speaker 2 (42:33):
But you can totally use.

Speaker 1 (42:35):
The same math to describe wiggles in other stuff, like
water in the ocean or sound waves in the air.
These are just wave equations, and the universe is kind
of wavy, and you can also identify particles of those
fields quanta of those fields. A phonon, for example, is
a packet of sound, the way a photon is a
packet of light. The math is the same, it's just

(42:57):
what's wiggling is not fundamentally universe stuff whatever that is,
but something else water or air or plasma or whatever.

Speaker 2 (43:05):
So we distinguish these.

Speaker 1 (43:07):
Things from particles by calling them quasi particles. But the
point is that the math still works, all right. So
to your question about the proton, we know the proton
is not a fundamental particle. It's made of quarks, so
there's no proton field, right. Well, actually, if you zoom
out far enough so you can't see the inside of

(43:27):
the proton, it kind of acts like a particle that
moves around the universe the way a particle does. And
you can pretend that there is a proton field. You
can write it down mathematically and use it to describe
the motion of the proton as a particle. And the
proton field is like an approximate description of the quark
fields dancing together. The way they interact together makes it

(43:49):
seem like there is a proton field, and until you
get enough energy that breaks that proton apart, it all
works just fine. And the same, of course, might be
true of the electron. We think that there is an
electron field, a fundamental part of space. But if the
electron is just made of other little particles, which are
the true fundamental particles, then the electron field is just
an approximate description of those fields dancing together.

Speaker 3 (44:12):
All right, So where do you go from there?

Speaker 1 (44:15):
So in this picture, particles are not little bits of stuff, right,
you have to give up that whole idea, that whole
mental picture we've had since Democritus that said the universe
is made of particles and particles are little bits of stuff.
Now we say, well, particles are not little bits of stuff.
They're wiggles in these fields. And that means something really deep.
It means that the universe is not made of particles.

(44:37):
It's made of fields. Particles are just something that happens
to fields. There's just something fields can do.

Speaker 2 (44:45):
You know. It's like discovering.

Speaker 1 (44:46):
Okay, ice cream exists in the world, but actually it's
not fundamental. Universe is not made of ice cream. There's
times when you don't have ice cream. There's whole periods
in the universe when there was no ice cream. It's
hard to imagine there was a moment when somebody invented
ice cream for the first time, right, and the universe
was filled with light. Yes, what it means is that

(45:06):
we've gone one level deeper though, right.

Speaker 2 (45:08):
This is the whole goal. It's like, what really is.

Speaker 1 (45:11):
At the foundation? What is everything made out of? And
this takes quite a left turn. It says, yeah, the
universe is not built of little bits. Those bits are
actually just ripples in these fields that fill the universe.
And I want people to really have an accurate visual
image of what these fields are because people think about, Okay,
a particle is a ripple in the field, or it's
an excitation in the field, And you should understand that

(45:33):
a field really is a wavy kind of thing. It
can do the same wavy kind of things that other
fields can do. You know, like imagine a guitar string.
What does a guitar string do when you pluck it,
you pull it back and so now it's like you're
stretching the string, right, we say in physics, now it
has a lot of potential energy because a lot of
tangent in there really wants to go back to its

(45:53):
relaxed position.

Speaker 2 (45:54):
What happens when you relax it?

Speaker 1 (45:56):
What happens when you let it go, Well, it flies
back to that relaxed position. But now it's moving really fast,
so now has a lot of speed, rights a lot
of kinetic energy. So it doesn't actually stop there when
it gets back to the relaxed position. It keeps going
and it bends the other way, and it oscillates back
and forth and back and forth and back and forth.
It slashes back and forth between potential energy and kinetic energy.

(46:17):
That's what a wave equation, and that's a wave like phenomenal.
I mean that slashes back and forth. That's what fields
are doing. Fields you can think of them as these
numbers in space, but those numbers are slashing back and forth.
The field itself has potential energy and kinetic energy. The
changing of those numbers has a speed to it. And
when we solve the wave equations for fields, what is

(46:39):
fundamentally quantum field theory the bedrock of modern particle physics.
That's what the solutions look like like. The Higgs field
is oscillating when we say a photon is an oscillation
in the electromagnetic field, We mean the values of the field.
Those numbers in space, Those arrows, they're moving, they're wiggling,
they're slashing around.

Speaker 3 (46:58):
So when I was in high school, we got the
like plum pudding model. So yes, I do think now
about particles as like a raisin embedded in something, and
not as like a wave function. If I were in
high school right now, would I be taught something more
like what you just said? How long have we known
about this stuff? Why does this feel new? Is what

(47:19):
I'm asking? Is it new? Or did I forget?

Speaker 1 (47:22):
It's a great time to ask me this question because
my daughter, who's taking high school chemistry right now, is
learning about this stuff and asking me questions about it.
So I'm getting like a front row seat too. How
are people taught about the nature of matter in high school? Yeah,
and yeah, they're taught about the plum putting model. Though,
just for the record, the plum putting model is not
a modern conception. It was like disproved by Rutherford, right.

(47:45):
People thought, well, maybe the universe is filled with this
jelly of positive stuff. Sounds tasty, but it's not the
way that we understand it. It's in contrast to having
like a hard dense nucleus at the core. So the
plum putting model, they teach it to them and then
they throw it out, but they don't really go very
deep into like the quantum mechanics of it. Even in
AP chemistry, I discovered they don't really talk about this stuff,

(48:07):
and they certainly don't talk about particle physics in AP physics.
So in high school you don't really get a whole
lot of this modern stuff. I teach modern physics at
the college level, and that's the first time we really
give people an understanding of the nineteen thirties concept of
what is a particle and how does quantum mechanics work.
And then we don't show them quantum fields until like
graduate school. So I didn't learn about quanum field until

(48:29):
I was in like eighteenth grade.

Speaker 2 (48:30):
So you know, this is not the kind of.

Speaker 1 (48:32):
Stuff that percolates mostly into high school. Maybe fortunately, maybe unfortunately,
I would love to have some of these ideas introduced earlier.

Speaker 3 (48:40):
So you think if you talked to just about any
recent graduate of high school, they're probably still thinking of
electrons as particles that stay in one spot.

Speaker 1 (48:49):
Tiny little dots orbiting the nucleus. Do you know Electrons
don't orbit, They don't have specific locations. They can't be
in one spot and have a specific velocity. You can
measure them here, you can measure them there, but they're
weird quantum objects. They don't go from here to there.
They don't obey all the intuitive rules that you expect
things that have specific locations to do.

Speaker 3 (49:10):
So we can all feel good about our advanced physics knowledge.

Speaker 1 (49:12):
Now, yes, exactly, you have pushed well beyond high school
and even college physics. And you know, I have to
underscore how powerful this quantum field theory approach is. To
say that all particles are just ripples and fields, and
the universe fundamentally is made of these fields. All space
is filled with many kinds of fields. You have one
for the electron, one for the muon, one for the upcork,

(49:34):
one for the down cork.

Speaker 2 (49:35):
We have more than a.

Speaker 1 (49:36):
Dozen fields that fill space. This is a really powerful
way to think about the universe. We see patterns in
these fields, how energy flows from one to the other,
their symmetries that they observe. It's allowed us to make
really powerful, very accurate calculations of all sorts of stuff
that we see happening in particle experiments, and so it's
really beautiful and really crisp and really clear. And I

(49:58):
think that most particle physicists this is what they think about,
or most theoretical physicists, imagine the universe as filled with
fields and particles as just ripples in them. But of
course it's a field filled with controversy, and so not
everybody agrees with that view. There are lots of people
who have a very different concept of what a particle
is and fundamentally how it all works at the bottom level.

Speaker 3 (50:20):
So to back up real quick, the field's theory has
produced loads of testable hypotheses that have been tested and
panned out. But there are still some people who think
maybe something else is going on that explains these resultss
and what are they proposing is happening.

Speaker 1 (50:37):
Then they suggest the fields are a fiction, that the
fields don't really exist, that the fields are basically just
a calculational tool we use in our minds to explain
what we see, because in the end, you can't observe
a field. You can't directly see a field. It's always
an intermedia thing like what you can see are particles.
You see those little dots on your screen, or you

(50:59):
see the electron deflected in your cathode ray. It's always particle,
like I'm doing air quotes when we see it, And
particles are what we observe, They're what.

Speaker 2 (51:09):
We interact with.

Speaker 1 (51:09):
Yes, we can use fields to explain them, and yes
we can think about fields as being out there, but
it's hard to argue philosophically that we know fields are
real in some way other than we can use them
to calculate these experiments. You can't like really directly see them.
And lots of famous physicists like Nima or Kanye Ahmed,
one of the maybe most brilliant modern particle physicists, calls

(51:31):
them a convenient fiction.

Speaker 3 (51:34):
Huh, So would someone like Nima then argue it's all
just particles, Like the field thing is throwing us off track.
We were on track with the particles, and we just
got to stick with thinking about particles and figure out
a way to measure yes at that level instead.

Speaker 1 (51:49):
Yeah, and here I want to take the opportunity to
disentangle something you hear about a lot in popular science.
People probably hear oh, particles or ripples in a field.
But they also hear this other story, like what happens
when two electrons repel each other, Oh, they exchange a photon.
They're passing a photon back and forth.

Speaker 2 (52:06):
Right.

Speaker 1 (52:07):
What you're doing there is rejecting the field picture. The
field picture of what happens when electrons push on each
other is an electron makes a field around it, the
electromagnetic field, right, and that field pushes on the other electron.
That's the field picture. People who don't believe in fields,
they're like, just explain it all in terms of particles.
You don't need the field. What happens when an electron

(52:27):
pushes on another electron is it throws a photon at
the other one. And so you can either explain everything
in terms of particles that are pushed by fields, or
you can explain it just in terms of particles and
say you don't need fields. Just go particles all the
way down. There are particles we observe, and they push
on each other by passing other particles between themselves. So
you can basically replace the fields with an infinite number

(52:49):
of particles doing all the pushing and pulling and all
that other stuff that some people say fields are doing
and the frustrating, slash confusing, slash amazing thing is that
you do the calculation since you get the same answer.
So is it particles is it fields? We can't tell
the difference because the two theories mathematically are equivalent. It's like,
either you can imagine these fields which fill space, which

(53:11):
are beautiful and elegant but kind of weird, like what
are they? Or you can say, I'm going to replace
those fields by a bunch of particles flying around doing
that same work.

Speaker 3 (53:21):
And are you a field guy?

Speaker 1 (53:24):
I was a fields guy until I read this book
about whether science can be done without math. You know,
people wonder like is math invented? Or is it something
in our minds? And there's a guy who developed an
alternative theory of gravity that doesn't use any math, no
numbers at all. It's called science without numbers, and it's

(53:45):
really weird. It's very alien. You read it and you're like,
what was this guy smoking? And where can I get some?
But he philosophically pulls it off. He shows that you
don't need to have fields essentially, and the crucial insight
in that book is to get rid of fields, because
fields are like numbers in space. So he divorces physics
from mathematics by ditching fields. My favorite part of the
story the guy's last name Fields. So Professor Fields gets

(54:10):
rid of fields, the field fieldless theory of physics. There's
lots of jokes you could make there, but it made
me wonder, you know, like our field's just something we
think about or they actually out there. When aliens come
and talk to us about their theory of physics, will
they have fields in it? Or will they have Schmields
or something totally different?

Speaker 3 (54:28):
So have you dodged my question or are you saying
that you're a particle person.

Speaker 2 (54:33):
I'm saying I don't know.

Speaker 1 (54:34):
I used to be a fields person, but now I
teach the controversy, got it?

Speaker 3 (54:38):
Okay? So when you first said that there were people
who reject fields, I thought that was going to get
us into string theory. Are we going to get to
string theory too? There's three options. So there's particles, fields,
and strings. Is that right?

Speaker 2 (54:51):
There's more than three options? Unfortunately?

Speaker 1 (54:54):
Okay, So there's lots of directions to go here. People
also wonder, like, well, what are these fields? Are fields
that bend ra the truth of the universe at the
firmament is that the thing that has to exist. And
it's sort of unsatisfactory because, well, why are there all
these different fields? Why do we have the electron and
the muon, which is like a weird heavy version of
the electron. Why are there these obvious patterns among the

(55:16):
fields that we can't explain. And one explanation for that
are strings, to say, well, none of these things are
what's at the bedrock underneath it all is something else,
and strings are this idea that the universe is not
made out of field to instead these one dimensional bits
of matter that can do wavy like stuff. They can wiggle,

(55:37):
and they can dance, and they can wiggle in various ways.
And if you're zoom down far enough so you can't
see the actual string bits themselves, when they wiggle one way,
it looks like an electron field, and when they wiggle
another way, it looks like a muon field, and when
wiggle a third way, it looks like a photon. And
so all these fields are actually just different wiggles in
these strings. This is another beautiful bit of mathematics. Nobody's

(56:00):
proven to be true or not, but might represent what's
going on underneath all of this, right, So maybe particles
are ripples and fields which are just wiggles in strings.

Speaker 3 (56:12):
So string theory is still a popular contender. I thought
maybe string theory was waning, but I'm you know, not
in this field. What's the current state of the string theory.

Speaker 1 (56:22):
String theory was very popular in the nineties. It seemed
very exciting. People discovered this math and could do all
sorts of fun stuff with it. And they've done a
lot of fun stuff, but they haven't been able to
prove that it's true because they talk about the mathematics
of the strings, but nobody can see these strings.

Speaker 2 (56:36):
The strings are too small.

Speaker 1 (56:37):
In order to see the strings themselves, you'd need like
a collideer to the size of the solar system, and
we don't have the funds for that. And so until
they make a prediction that we can actually test it,
say like, oh, string theory, if it's true, we should
be able to see this thing, then we don't know
if it's just mathematics or if it's actually a description
of the universe. And so there's been a lot of
people who are negative about string theory for that reason.

(56:59):
I still think it's exciting, but there are other ideas
out there about you know, what the universe could be
made out of?

Speaker 3 (57:05):
What else?

Speaker 1 (57:05):
As you were saying earlier, we tend to think about
the brain as made out of whatever is the latest
technology in the same way we try to think about
the universe that way. Like the advent of quantum computing
makes us think about cubits and information And there's a
whole line of argument that I think we should talk about,
probably on another episode, about whether the whole universe is

(57:27):
just a quantum computer and particles are like patterns and
the flow of information in this quantum computer. There are
folks who do these experiments that discover that if you
build a space time from entangled cubits, that these patterns
naturally arise, which have properties that align well with.

Speaker 2 (57:44):
The particles that we see.

Speaker 1 (57:46):
This is all really very speculative stuff, but it's sort
of the forefront of current research. People wondering, like, what's
underneath all this stuff? Maybe it really is even different
than democratists imagined, or Schrotinger or even Fineman.

Speaker 3 (57:59):
What is a cubit.

Speaker 1 (58:00):
A cubit is a quantum analogy to a classical bit,
like in your computer. A bit is something that can
be zero or one. It's like the minimum piece of
information you can have. It's boiled down to just two options,
like a switch you can flip. And a normal bit
is in one state, but a quantum bit has a
probability to be in one state or in the other.
It's not necessarily in one or the other. So it's

(58:22):
a cubit is a quantum bit. And people wonder if
fundamentally the universe is made out of cubits that are
somehow woven together to make space and time and our reality.
But we'll dig into that in a whole other episode.

Speaker 3 (58:35):
Awesome, all right, So if we tomorrow were to find
out which one of these explanations was correct, what would
that change? So that would be satisfying, But where could
we go from there? That would be even cooler, Like
what doors would that open up? For us?

Speaker 2 (58:51):
Yeah?

Speaker 1 (58:51):
Wow, awesome question. You're basically asking, like, why do we
care about any of this? So what does it mean
for us? For me, it's like really deeply important and
to understand what is the nature of the universe we're in,
You know, what is it made out of? If you
told me the universe starts from these conditions, and everything
else follows from that, Like to have a universe, you

(59:12):
have to have space and time and this little bit
of stuff, and then everything else, all the complexity, the blueberries,
the kittens, the lava, the podcast, all that comes from
how that stuff is arranged and interacts.

Speaker 2 (59:23):
And that's cool.

Speaker 1 (59:24):
I want to know what is the most fundamental thing,
because that tells me something deep about the nature of
the universe. If it's this, then the universe is that
way in some deep wave. It's that the universe is
another way, in some deep way, and I just fundamentally
want to know. It doesn't change how you drink your coffee,
it doesn't change how you treat people. It doesn't change
what investments you should make. But it changes what it

(59:45):
means to be alive in this universe in a really
important way.

Speaker 2 (59:48):
To me. It's very uncomfortable that we don't know the.

Speaker 1 (59:51):
Answer to the basic question of like, what is the
fundamental building block of the universe we live in. It's
like being born into a jail and not knowing who
built it or what's in the outside. It's like, I
want to break out of this ignorance.

Speaker 3 (01:00:06):
I found myself personally wanting the answer to be that
everything is a field and it's sort of connected in
a way that feels like, I don't know, maybe sort
of like kum bay us sit around a fire sort
of feeling. But I like that stuff, so anyway, I
guess my gut wants that to be the answer. But yes,
I think it would be good for us to know
the answer to this very fundamental question.

Speaker 1 (01:00:25):
And I suspect the answer is none of these and
something even weirder. That's going to be so difficult for
us to understand. It's going to be a stretch to
even explain in terms of our intuitive language of concepts.
You know, we're going to have to use kiwis and
fields and particles and strings and all sorts of other
stuff to try to wrap our minds around the way
that we universe actually works, which has no guarantee that

(01:00:46):
it's even understandable to us.

Speaker 3 (01:00:48):
So people are going to be like Democratus thought it
was sour because it was like little knives, and then
Daniel and Kelly thought it was like strings and fields.
What idiots? So you know, who knows what they'll think
in a hundred or so years.

Speaker 2 (01:01:00):
I hope they're laughing at us. In one hundred years,
that would be awesome.

Speaker 3 (01:01:03):
Yeah, progress is good.

Speaker 1 (01:01:05):
All right, Well, thanks everybody for taking this journey with
us from the ancient misunderstanding of what matter was to
our modern misunderstanding of what matter is. And we hope
to continue this journey and to slowly chisel away towards
some actual, solid understanding.

Speaker 3 (01:01:19):
Have a good week everyone. Daniel and Kelly's Extraordinary Universe
is produced by iHeartRadio. We would love to hear from you,
We really would.

Speaker 1 (01:01:34):
We want to know what questions you have about this
Extraordinary Universe.

Speaker 3 (01:01:39):
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