May 26, 2020 • 39 mins
Daniel and Jorge explain how the theory of "Renormalization" tells us that we measure is different from what is real.
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Speaker 1 (00:08):
Hey, Orry, remember a few weeks ago when we criticized
Albert Einstein. I remember you criticize Einstein. Well, you know
he added a big fudge factor to his theory just
to make it work. Yeah, it was a pretty big
fudge factor. I guess it was a little bit embarrassing
for the old genius. It was sort of a universe
size fudge factor. Well, you know, it turns out maybe
I shouldn't have been so critical because particle physics has
(00:31):
some fudge factors of its own. Particle physicist shouldn't be
throwing stones at glass theories. That's right, we got some
whoppers of fudge factors. Are they Einstein size? Are they
really big? Well? Does an infinity count is really big?
Does nothing count as really small? I think so. I
(01:06):
am more handy cartoonists and the creator of PhD comics. Hi,
I'm Daniel. I'm a particle of physicist, and I'd just
like to point out that Jorge is not just a cartoonist.
He also has a PhD from a famous university. Thank you.
I'm glad you think it's a famous university, you being
on the other side of the Bay Area. It's famously
the second best university in the Bay Area, even enough
(01:28):
to Santa Clara University. I think that's probably true. But
welcome anyway to our podcast Daniel and Jorge Explain the Universe,
a production of I Heart Media in which we take
you on a tour of all the incredible, amazing bunker
stuff in the universe, from tiny little particles that don't
really spin too enormous galaxies that spin mysteriously. Yeah. We
(01:49):
go from the crazy maybe ideas that physicists have about
the universe to the actual nitty gritty theories that they have.
Because everybody is curious about our universe. How does it work?
What's really happened? The search for truth and understanding is
as old as human consciousness. And here we take you
on some of the last steps and we try to
bring you up to speed to what scientists are thinking
(02:10):
right now. What model is in the head of particle
physicists when they think about a particle. How does a
cosmologists think about the whole universe? Yeah? And are they
right or are they just making it up as they
go along? And doesn't make any sense? And what does
it mean if the universe doesn't actually make sense? Oh? Boy,
now you got me worried. Well, after today's episode, you'll
(02:33):
discover that it's all sort of well. These days, the
universe doesn't seem to make a lot of sense. But
fortunately that's what we're here for, and that's what physicists
are here for, to try to put some order into
the universe. And so today on the program, we'll be
talking about a particular I don't know what do you
what would you call it a whole in your theory
of the universe or a hole in your theory of matter.
(02:54):
It's sort of like a shift in your perspective. We're
used to thinking about particles in one certain way. What
is their spin, where is their mass, what is their charge?
But we discover that didn't really make a lot of sense,
and what we had to do was think about particles
in a totally different way. I see. So when something's
wrong or there's a big hole in it, you just
you just call it need to shift our perspective. That's right,
(03:16):
let's just sweep all that under the rug and then
called the rug our new idea. That's essentially what's happening here.
But that's you know, that's an important part of physics
when you have a model and you push on it
and push on it, you discover it doesn't actually quiet work,
and then you have to accept something counterintuitive, something new,
a new perspective on the universe, but one that actually
does work mathematically. That's right, and so to be on
(03:38):
the program, we'll be tackling the question what is renormalization.
Is it just a fancy physics word for making stuff
up and pushing all the infinities under the carpet, or
are we going to talk about when things will go
back to normal in this crazy world we live in
right now? That's what I was hoping for, or when
(04:00):
I saw the title, Daniel, I would not rely on
particle physics to make things normal. It reveals the bonkersness
of the universe. It reveals how the universe is so
hard to grasp, and we're in this constant journey of
trying to map our understanding of the universe onto the
microscopic to think about these little objects electrons and photons
in terms of quantities that we find familiar, you know,
(04:22):
mass or charge or spin. But it's a struggle, I see.
You have to sort of assume the opposite when a
particle physics is walks in you're like, let's throw normal
out the door. It's buckle up and get ready for
a journey to the weird, because that's where we all live.
All right. Well, this is a pretty interesting idea, and
it has to do with your theories about particles and
(04:44):
matter and that they sort of don't always work or
there's holes about them. Yeah, it's sort of akin to
how if you try to describe particles in terms of
particles like tiny little dots of stuff, that doesn't always work. Right.
We see particles sometimes having produce like waves, right, they interfere,
and so we have a broader sense of these things.
(05:05):
They're not just little dots of stuff. They're these weird
quantum mechanical objects. It can be like waves and like particles.
So that's an example of how you might have to
broaden your concept of a particle. And today we're gonna
have to broaden it again, sort of in a different direction,
because the idea we had about particles carrying these little
numbers with them doesn't actually quite work when you sit
down to do the man. I was just wrapping my
(05:27):
head around that idea. Daniel, you're saying it doesn't apply
or doesn't quite tell me, what's happening in the universe? Yeah,
And you know what we do is we have this idea.
We say, let's give these little dots in space, these labels,
these numbers will say charge mine is one mass of whatever,
spin of a half, and then let's see if it works.
And when you run the numbers and try to compare
(05:48):
it to what we see in experiments, it doesn't actually work.
And it tells us something sort of deep and weird
about what the particles are and what they aren't. Sounds
interesting and I want to know more. But at first,
as usual, Daniel went out there into the wilds of
the internet to ask people if they knew what renormalization was.
That's right, So thank you to everybody who volunteered to
(06:11):
answer a random person on the internet questions. Before you
listen to these answers, think about it. Have you heard
of the term renormalization or would you even know or
guess what it could mean. Here's what people had to say. Um,
maybe something happened to you and you are becoming normal again.
(06:31):
I do not know, no clue. I my guests would
be to bring something back to normal after a change.
I'm not sure when something goes normal again. What happens
if you don't know what any of the words. I
(06:52):
really don't know. It's not a term I've heard before.
My guess is it has something to do with phenomen
of maintaining order in the universe. We've learned something new
about space or um, so, whether that's on a cosmic
scale or a particle scale, and we need to change
(07:15):
our assumptions that go into our equations based on the
nearing side. Well, it seems like some people have the
same idea you did, are going to go back. I
think getting back to normal is probably high on people's
mind right now. But I like, yes or there where
the person just said doesn't mean becoming normal. Well, I've
never been normal, so I can't really speak to them.
(07:37):
All right, Well, this sounds like a normal word, renormalization,
but I'm guessing it has some pretty deep mathematical consequences here.
For particle physics, it comes from the word normalization, and
normalization is just to make something normal. But in mathematics,
when we say making something normal, we don't mean make
it usual or typical, or you know, like when you
(07:59):
were a kid it. What we mean is that we
make it all add up to one or fix it
to some specific number, right to sort of calibrate it
almost in a way. Yes, calibration exactly. And so renormalization
is like, oops, something went wrong and now we need
to do it again. It's like, you know, you thought
you had your spendometer working correctly on your ferrari, and
(08:19):
then it turns out you were going one sixty when
you thought you were only going eighty. So you gotta
recounty account. You gotta renormal make it normal again, make
it normal again, make it the old familiar ferrari or
electric charge that you knew when you were a kid. Okay,
And that's exactly the issue here is that we ran
into a problem when we were trying to calculate the
electric charge of the electron. It sounds pretty basic, isn't
(08:43):
the electron something we've known for a long time and
know what the charges? You think? So, right, it's sort
of like how we defined electric charge. It's like, you know,
Ben Franklin or whoever you know first identified this as
moving charges. Define charges to be plus and minus, and
that's where the electron charts comes from, right. It's the
carrier of the minus one charge, is like the definition
(09:04):
of what the charge is, right right? Oh, I see,
So an electron has a negative charge one, it's sort
of the definition of charge. What are the units electronus? Well,
you know, it's defined in terms of cool ombs, but
it's a crazy number in terms of cool ombs, and
so we just in particle physics, we'd like to drop
all the units and redefined everything, and so we just
call it one e like one electron charge. That's the
(09:27):
unit alright, So it's kind of like the standard. It's
kind of like the standard. But the problem is if
you say, okay, I have a little particle and I'm
gonna put a minus one charge on it, and then
you put that into an experiment and try to measure
the charge of it, you would actually measure zero. Like
you shot other electrons at it, you would measure almost
(09:48):
zero charge. It sounds like a big area here. You're
expecting minus one and you got zero. Yeah. So the
electron can't have charge minus one because if it did,
we would measure zero. And the reason is that the
electron is never just by itself, right, It's not like
a whole universe populated by just an electron. Instead, the
(10:08):
electron is surrounded by space and space is never empty.
We've talked to this podcast a lot of times how
space is not just the backdrop of the universe. It's
this crossing quantum mechanical weirdness that can do stuff we
don't understand, like expand and wiggle and stretch, and their
deep theories about space that people are working on. We
(10:28):
talked about Steve Wolfram's idea about space and quantum foam
space and like it's a huge question marks empty space
is not empty. Empty space is not empty space. Sometimes
that space out when I think about it, but there's
a lot of it. That's the one thing that's still true.
There's something to it, and somehow that's affecting what we
measure about the electron. Yeah, because space is filled with energy,
(10:52):
and energy can turn into virtual particles, particles that pop
in and out of existence really briefly. And when that happens,
usually you get a pair of the particles like a
plus one and a minus one that pop out together
because it has to balance out, like you can't just
introduce more negative charge into the universe. You kind of
have to balance it out. That's right, There still follows
some rules, right, Virtual particles are not a total free
(11:14):
for all. They still have to observe the rules of
the universe, and one of those is that the pluses
in the minuses have to balance out. And so essentially
any electron is surrounded by a bunch of positive negative
charged particles. So then the electrons field, the electric field
that it creates, it pulls on the positive part of
those virtual particles, and it pushes on the negative part
(11:37):
of those virtual particles. But they don't exist. They do exist, though,
they do exist briefly, right and constantly. It is a
frowthing swarm of these particles. And so what it does
is it like polarizes the vacuum. It pulls the positive
part of these virtual particles closer, and it pushes the
negative ones away, and it has the effect of essentially
(11:57):
shielding the charge of the electron. Oh, I see, But
they don't exist, though, do they They actually pop into existence?
They do exist, They actually do pop into existence. Yeah,
And you know, this is the kind of effect that's
very familiar. Like the reason you can't use your cell
phone inside an elevator is that electromagnetic field can't penetrate
very well through metals because metals are filled with little
(12:20):
charge carriers electrons, and when electric field passes through metal,
the electrons will like rearrange themselves to cancel out any field.
It's called a Faraday cage. Okay, So then if you
have an electron, it's gonna pull these virtual plus particles
to it, which then cancel it it out. Is that?
What is that kind of what you're saying? Yeah, but
these per virtual particles are also like possetrons or are
(12:43):
they you know, imaginary? Are they actual like you know,
ions or muans or what are they? They're actually all
kinds because you can have any kind of virtual particle.
You can have virtual particles that are pairs of electrons
and positrons, like you said, you could also create muons
and anti muon. You can create quarks and antiquarks. You
can create anything you like out of the vacuum as
(13:05):
long as you observe the conservation laws, and then most
likely you're going to create the lowest mass particles. So
usually you're going to get things like electrons and positrons. Okay,
but they're sort of virtual because they're popping into existence
and popping out of existence. But there's enough of them,
and there's a constant popping in and out of existence.
That effectively they are real. They count as if they
(13:26):
were there. And so what happens is that you you
shield the true charge of the electronic it reduces it.
It like screens the charge sort of like if you
want to know how cold it is in your freezer,
but all you can do is measure on the outside. Well,
you're not really measuring the true temperature inside your freezer, right,
You're shielded by all the insulation, and so that's essentially
(13:46):
what's happening here. So then if all electrons then are shielded,
how do they even work? Yeah, Like if I have
two electrons in space and they're shielded, then they wouldn't
repel each other. That's true if electrons charge is actually
minus one, But it's not. That's the kicker, that's the renormalization.
The charge we measure is minus one. Right, electrons do
(14:10):
repel each other. You're right, electricity is real. Right, we're
not repealing electricity today in the podcast, which is canceled
the electricity exactly. But what we've discovered is what we've
been measuring for more than a hundred years is not
the true charge of the electron. It's this shielded charge.
We're measuring the electron on the outside of the freezer.
(14:30):
That charge is minus one. What is the electrons true
charge behind all that shielding? That was the new question. Oh,
I see it's in the freezer, and we didn't really
know how cold it is or how electrically charge it is. Yeah,
and we sat down to do these calculations. We realized, wait,
isn't there a big effect from this freezer, from this shielding,
from the screening, from all these virtual particles. And people
(14:52):
started calculating. The realized, yeah, there is. So if electrons
had charge actually minus one, we should be measuring zero
charge experiments, but obviously we're not. So they went back
and they said, how much do we have to dial
up the charge of the electron before we get a
measure charge of minus one to extrapolate through this cloud
(15:14):
of particles and say, what's really going on in there?
So what we see of the electron when we measure
as its charge is what we measure through the installation,
this virtual installation that that you're talking about. That's right,
and so the question is what's its true value inside?
That's right. Let's pull back a layer of reality and
say what is really happening. Okay, it's not just minus too.
I'm gonna guess you know it's gonna be totally unsatisfying
(15:36):
and frustrating, like usual with particle physics. Great, well, I'm
looking forward to Daniel. So let's get into it, and
what does a real charge means of the for the
electron and for mass and for the entire universe. But
first let's take a quick break. Al Right, So an
(16:06):
electron doesn't have the charge of an electron apparently depends
what you mean by an electron. Up is not up,
and the electron doesn't have electron on an electron. No,
it's really it's about definitions, and that's where we're gonna
end up today, is talking about like what it means
to be an electron. Because the thing we measure you
call that an electron. You know, some weird quantum dot
(16:26):
with all of its shielding and fuzziness and virtual particles
all around it. That thing has charged minus one. But
if you try to penetrate that cloud and say this
bit at the core, the true electron, the fundamental electron.
Because we're interested in understanding the deep nature of the universe,
not like the effective, messy, sloppy things we can actually measure.
(16:48):
We want to, you know, penetrate all the way in
and see what's really happens to see it's not I
guess celebrity. You know, they're surrounded by all this hype
and people and you never know really who they are
on the inside. And so that what we're doing today,
we're peeling back the layers of stuff to get a
real sneak pick at the electron inside. That's right, So
what what is the real charge in of the elector
(17:08):
when you get through the electrons entourage? What you discoverage
is to make the measure charge minus one, you have
to set the true charge. And particle physics we call
this the bare charge, like an electrono by itself to
minus infinity, like what the bare minimum? You know, just
(17:30):
a small thing like minus infinity. I know. I remember
learning about this and thinking, oh, renormalization. Okay, so you
gotta adjust the charge of it's going to go down
to one and a half or two or whatever, and
then discovering you gotta minus infinity. What that doesn't even
make any sense? That's great. You can't call that renormalization.
(17:52):
How can how can you say that an electron has
a negative charge of negative infinity. What does that even mean?
It's hard to understand, and you know mathematically what happening
is that the more the electron is charged, the more
it gets shielded. Like, the more powerful its charges, the
more it polarizes the vacuum around it. If you crank
it up to minus two, you don't get much measured charge.
(18:12):
You've got to really crank it up incredibly just to
get any measured charge because it works against you. There's
no limit to these virtual particles. I mean space is
full of them. And then what does it mean, like
whenever you discover an infinity and particle physics, space is
full up to infinity, Like space has an infinite number
of virtual particles all the time everywhere. Yeah, an infinite
(18:34):
number of virtual particles. That is true, it's not an
infinite amount of energy. So there's an infinite number virtual particles.
The number of them increases as their energy decreases. So
it's rare to get a high energy virtual particle or
a high mass virtual particle. It's totally common to get
an almost zero energy particle. That the smaller the energy,
(18:55):
the higher the probability and so as that goes to zero,
you literally get infinite numbers of particles. But anytime you
get infinity in a particle physics, like you say, okay,
this particle has minus infinity charge, that tells you you're
doing something wrong, not just this particle. Imagine it then
applies to all particles. Yep, this does actually apply to
every single charge particle in the universe. That's right. So
(19:18):
that's a pretty big problem. And you know, we should
not be throwing stones at Einstein when it comes to like,
you know, by making big corrections to basic facts about
particles in the universe. So so my intuition tells me
that it's it seems implausible, if not impossible, for every
particle in the universe who have a infinite charge. So
(19:38):
I guess, step me through what's going on, Like, where
does our model of the universe break that we have
to do this fudge? If it is a fudge, No,
it's it's sort of a fudge. But what you have
to do is renormalize your theory of a particle, your
idea of what a particle is. Like we've been thinking
about electron as a tiny individual dot, like a basic constituent.
(19:58):
You know many lego brick out of which stuff in
the universe is made out of, right, But instead that
doesn't physically make sense. It has to have negative infinity charge. Instead.
You need to think about the electron, not by itself.
The whole concept of an electron only makes sense together
with this virtual swarm of particles. So that's not separate
from the electron. It's not just an electron in the freezer.
(20:21):
The freezer is part of the electron. Oh I see.
Just gonna pull back your definition and ignore what's inside
of the freezer is kind of what you're saying. That's right.
It's like you say, hey, I'm not going to clean
up my living room. Messiness is my new living room,
and that's just you know, this is how I live now.
This is the new clean. Right, that's a renormalization. Oh
(20:42):
I see, okay, God, messiness is a new clean, Infinite
particles is a new emptiness, and negative charge isn't a
new minus one? Right, and space is the new not nothingness.
Trust me, this all makes sense. Okay, got it? Got it?
So I think that's kind of what you're saying is
just ignore what's inside of the freezer and just don't
(21:04):
open the freezer. Don't even think about what could be
in there, growing you know, who knows what. Just lock
the freezer, throw away the key, and just deal with
the freezer. Yeah, And the thing to remember is that
when you get an infinity to the answer to a
physics question, it tells you that you're asking a question
that doesn't really make sense or that isn't really logical.
Here is another simple example. Say you wanted to know
(21:26):
what's the force on my head from all the stuff
in the universe that's on my left. Well, the universe
is infinite, then there's literally an infinite force of gravity
and electromagnetism and all that stuff on your head from
that side of the universe. Now there's a whole other
side of the universe that also has an infinite force
from the right side of the universe, right, and and
(21:49):
they cancel each other out to get basically zero force.
So asking that kind of question just means there's an
artificial distinction that you've introduced. The infinity comes only because
the question you're asking doesn't really make sense, like what
is the left side of the universe or the right
side of the universe. In the same way, trying to
separate the electron from the rest of the universe and
(22:09):
asking what is its charged all by itself, that doesn't
really make sense. You have to think about the electron
as part of an interaction. I mean, the electron has interactions.
It It sends off photons constantly. It's not doesn't really
make sense to sort of draw a dotted line just
around it and say, only think about this bit. I
think I understood that a negative infinity amount. I feel
(22:33):
like what I feel like you're saying, that's just ignore
this little weird fact and just not think about it
and just go with the flip. No, don't ignore it,
but just redefine the question you're asking. It's just like
in Douglas Adams. You know, if you ask a question
and get a nonsense answer, you have to go back
and think about maybe I should ask a better question.
In this context, asking what is the charge of the
(22:53):
bare electron doesn't really make sense because that's not a
physical thing. You will never have a bare electron. There
will never be an ale tron without its entourage. That's right,
only in a universe in which there is only electrons
and there are no interactions at all, which can't exist.
So I guess you're saying that what's inside the freezer
doesn't matter because we'll never open the freezer, or they'll
(23:15):
never be something without a freezer, that's right, And we
can't open the freezer. So even though you would predict
that there's negative infinity charge inside of the freezer, that's
probably not what's going on because we don't really know
when we never will open that freezer. Yes, except we
have ways to partially crack open the freezer. Yeah, all right,
(23:36):
because this is a virtual cloud of particles, right, and
we can penetrate it. Like if you shoot an electron
at another electron really hard, it will get through more
of that virtual cloud. Then if you shoot an electron
at it really gently. And so it turns out that
the harder you shoot one electron at another, the stronger
(23:56):
the charge you measure. So the charge of the actron
depends on the energy of the particle you're using to
measure it. So the electron doesn't just have a charge
of minus one that you measure or minus infinity inside
the freezer. The answer depends on how much you've cracked
(24:17):
open the freezer, how much the entourage gets out of
the way, or something. Yes, so you can get through
this virtual cloud of particles partially. You can never get
all the way, but the more you probe in there,
the stronger the charge of electron that you measure. So
it's sort of is like a real physical thing. You
can poke at the freezer and kind of take a
peek inside, and it does look like it's almost negative affinity.
(24:39):
Is that kind of what you're saying. Yeah, you can
never get to negative infinity, but the higher energy you
probe with, the stronger the charge you measure. And so
that's also sort of like, you know, a bit of
a brain scramble. You're used to thinking of the charge
of the electron as a basic fundamental constant, right, Well,
it turns out it's not constant. It depends on the
energy at which you're probing the electron. So the charge
(25:02):
of an electron is not then one of the fundamental constants. No,
it's not, or basic constants not. And we talked about
this on a podcast recently, how there's a different constant.
It's called the fine structure constant that includes the charge
of the electron and the speed of light and planks
constant because those things themselves are not actually fundamental constants.
(25:23):
Only in combination the ratio especial ratio of those things
are fundamental constants. I see. So I guess what you're
saying is that if I shoot an electron with a
fast enough electron, I would maybe measure it's charged to
be negative infinity. Yeah, it had to be infinitely fast
electron that you're shooting. The faster the electron that you're
using in your gun, the stronger the charge you measure
(25:46):
on the electron. Well, I feel like we're throwing infinities
all around, So why not let's just throwing infinite a
number of infinitely fast electrons. Now there's just no rules, right,
It's like whatever anything can happen doesn't even matter. All right. Well,
that that's pretty wild to know that the electron has
this kind of hidden and maybe infinite charge. And so
(26:07):
I guess the question is, how does that affect what
we thought about the universe or how we look at
things like mass or you know, effic goes to me
and all that stuff. So let's get into it, But
first let's take a quick break. Al Right, So apparently
(26:34):
the electron has possibly a negative infinity charge if you
can get to it, if you can get past a
cloud of virtual particles that surrounded and protected and kind
of shielded from the rest of the universe. And so
that's a wild concept, Daniel. Now, what doesn't mean about
what we know about the electron? Well, it's not just
the electron. Remember, all charged particles have the same property
(26:57):
that they shield themselves. And what we're measuring is really
the variable strength of the electromagnetic interaction. And the higher
the energy you have, the stronger this interaction is. And
so what it tells us is that the particles by
themselves is unique. This bare particle, the stripped of all interactions,
is not a physical thing that we should be thinking about.
(27:18):
And we need to renormalize our idea and think about
the particle together with its entourage. That really defines who
it is. Because you know, if you met a celebrity
without their entourage, they probably wouldn't seem that famous either,
would they. It seemed normal and down to earth. I
don't know, you tell me you've met me in person, Daniel,
what is that? I had to fight my way through
(27:39):
your entourage? Um? All right, So so that's kind of
what this renormalization means. It's like kind of like getting
used to the entourage of particles, and it doesn't just
apply to the charge. It turns out that most of
the fundamental characteristics of the particles have this same property,
that they have a measured value and then a weird
(28:00):
it's sometimes non physical sort of bear true value. I mean,
like some of the other quantum charges like color and
spin and things like that. Just like that. Yeah, the
strong nuclear force also has its strength vary with the
energy of the particles that are shooting at it. But
I think one of the weirdest things is the particle mass.
(28:20):
Like we think about mass and sort of like a
defining characteristic of a particle, like what's the difference between
an electron and muant while a muan is heavier, right,
And we identify particles by their mass, But it turns
out that what we measure, and we measure the mass
of the particle is not actually like the true fundamental
mass of the particles, not the mass the particle would
(28:41):
have if it was all by itself in the universe
with no interactions, right, because instead of virtual particles that
it interacts with, it interacts with something else, the Higgs field. Right,
that's right, all particles moving through the universe are interacting
with all the quantum fields that are around them, and
what happens when they interact is that you know, those
fields amid little particle for them to interact with. And
(29:01):
so you can imagine like an electron flying through the
universe and it can emit the Higgs boson and then
it can reabsorb that Higgs boson. That's effectively what's happening
when it's interacting with the Higgs field. It emits a
virtual Higgs boson and then re absorbs it. And it
can do that, or it can do admit to Higgs bosons,
or that Higgs boson can split into other particles and
(29:23):
then come back together. There's millions of different possible things
that could happen as an electron is moving from A
to B. And so we've talked before on the podcast
about how the Higgs boson gives particles mass, and we
say this this field that fills the universe, and interacting
with that field gives those particles masses. But we sort
(29:43):
of dot dot dotted over that critical bit, like how
does interacting with a quantum field give a particle mass?
What does that mean? Right? Well, there's the analogy of
like moving through a crowded party or something, right, Like
you're trying to move, but the field is throwing particles
at you, and you're throwing particles at and that's kind
of what inertia sort of is. That's exactly right. And
(30:04):
if you want to go from A to B and
you talk about a particle having mass, then it takes
energy to speed it up as it's going from A
to B, or it takes energy to slow it down,
and it turns out that's inertia, right, And that can
be exactly modeled as a particle interacting with the field
because as it goes along, you can admit a particle,
you can absorb a particle. There's all these complicated interactions
(30:25):
that can happen, and those interactions have exactly the same
effect as if you just gave a particle inertia sort
of by hand. Those interactions all add up to create
this effect that we describe as mass. Like it again,
this is a separation between like our macroscopic observations of
stuff and the microscopic explanation for what's really happening, and
(30:49):
the macroscopic thing were familiar with is like, hey, stuff
seems to have inertia. You know, you push on a
heavy rocket, takes a while to get it going. You're
downhill from a heavy rock, you better move out of
the way because it's hard to slow down, right, And
that macroscopic property turns out to be explained by all
the little particles inside it interacting with the Higgs field,
with virtual particles, with virtual particles exactly, that's the key,
(31:12):
are you saying, sort of like all particles, and it's
not just their electrical charge, You're saying their mass. It's
also kind of insulated by these virtual Higgs boson clouds.
I'm saying that what we call an electron that has
mass is actually an electron with a swarm of Higgs
bosons around it. That's what it means for an electron
(31:32):
to have mass, is that it's sort of clouded by
the Higgs field. And so an electron moving through universe
with no Higgs field would have no mass. Right, So
what we call the electron is not really just the electron.
Is the electron surrounded by this swarm of virtual particles
it's constantly interacting with. So in the same way we
renormalized our concept of the electron as the electron surrounded
(31:55):
by its virtual screen of particles shielding its charge, we
all also have to include for the electron when we
think about its mass, we have to think about this
virtual cloud of particles it's interacting with, because that's where
it gets. It's like, it's like kind of like what
you're saying is that all of these quantum fields and
the universe are all sort of connected to each other,
(32:15):
and so you can't really talk about one thing because
it's it's all connected everything. Nothing can exist on its own.
That's right. We've got pretty spiritual pretty quick there. Man.
Maybe we're connect Man, it all is just a renormaliz
past that do be over here, man, I want to
(32:35):
be normalize. Yeah, exactly. Got to smoke your banan appeals.
And you've got to understand that these particles, they're not
on their own. They're just fluctuations of quantum fields, and
these fields are all interacting with each other, and so
it doesn't really make physical sense to say, what is
the mass of this one little particle, what is the
charge of this one little particle. You've got to think
about it together. But you're sort of saying that particles
(32:57):
don't have mass without the Higgs field, right, that's exactly right.
If there was no Higgs field, these particles would all
have zero masses. And so the bare mass of these
particles in the limit where you think about the non
interacting is zero. All the particles in the Standard model
except for the Higgs boson, have bare mass of zero,
and they all get their masses through this virtual swarm
(33:18):
of craziness. And it's not just actually through interacting with
the Higgs. Like the electron also gets more mass because
it emits photons. I know, that's especially weird because photons
have no mass. Right, in addition to interacting with the Higgs,
they get mass from photons. That's right, they get mass
from photons. And now, if there wasn't the Higgs, the
electrons would have no mass. But because they're the Higgs,
(33:39):
photons can add mass to the electron. It's like multiplicative,
like they make it have, you know, they multiply its
mass by a certain factor. If it was zero would
stave zero. But since the electron gets some mass from
the Higgs, the photons boosted. Remember mass is also related
to energy, and in a sense, what we're talking about
is how the electron has a lot of self energy.
It's constantly emitting and absorbing a swarm of photons, and
(34:03):
those contribute to its effective mass, which is what in
the end we measure. We only measure, you know, physical things.
We can't actually measure true things about the electron. If
it was all its only in the universe. I feel
like you guys wanted to call it naked charge, but
you were, but you still have backed down. You're like
to naked charge, but we can't. It's called naked charge.
It's called bear charge, and thus confusing everyone because they're
(34:24):
like bears. What do you mean, like like a bear? Exactly,
it's one of the bare necessities, you know, exactly, all right,
But then does the electron then have a constant mass
or does it also vary like it's charge, It also varies. Yeah,
all these quantities actually vary with the energy you're using
to probe it. But last time we talked, that's in
(34:46):
the mass of the particles were constant in the universe. No,
you're totally right, And what we actually mean when we
say those constants is we mean the strength of the
interaction with those particles and the Higgs field. That's what
controls the mass but the mass of you measure and
individual experiment does depend on the actual energy of that experiment. Wow,
(35:07):
so now we also have to redefine mass mass um
doesn't exist. It seems it's inside the freezer. Yeah, everything's
inside the freezer. This is something that helps you also
understand how the universe could have been very different in
its early years, because in the very early moments of
the universe, Remember, things were hot and dense and nasty,
and all the particles had a lot of energy, and
(35:29):
all these forces charge, and the strong nuclear force and
the weak nuclear force, all of them depend on the energy.
And so back in the early days of the universe
we think that maybe all the forces had the same strength,
and that what's happened since then as things cool down
and things got slower and calmer, is that these things
have different like variations with energy. You know, one of
(35:51):
them drops really quickly as things go to low energy,
another one drops really slowly. But back in the early days,
things were glorious and unifisity. Back then, thanks are normal
Then we denormalize kind and now we've got a renormalize.
You got a normalize. And but I have to say,
none of this makes me feel normal at all, Daniel,
you just told me that the electron doesn't have a
(36:14):
charge and it doesn't have mass, so it's not easy
also for particle physics to accept this. There are a
lot of years when after people made this discovery that
you have these weird infinities in the theory, that they thought, well,
the theory must just be wrong, right, there must be
a problem with the theory. And then people realized, oh, well,
you know, you just redefine what you mean by an
electron and then you don't have to worry about those infinities.
(36:35):
And a lot of people objected. They were like, you
can't just do that. You can't just define your living
room to be clean now, but if you don't have
any better ideas that you can. But but but it
turns out you can. If yours is the only house
in the universe and you're the only one person living there,
you didn't define it however you want. But then there
was a guy Ken Wilson, who is sort of an
(36:56):
underappreciated genius, who sort of made a deeper point about
the whole nature of the universe, and he said, you know,
nothing is really constant. Everything depends on energy the physics
you measure depends on the energy you're using to measure it,
so it's totally natural for things to vary. In fact,
the mistake was to expect anything to be constant. So
he said that the grandest renormalization of them all. I see. Wow,
(37:20):
he like dropped the mic. He's like, bam, I just
redefined normal exactly. He redefined what success was. All right, Well,
I think it's pretty interesting and mind blowing to like
think about what happens when you actually get down to
that level. You know, when you try to get down
(37:40):
to the zero size of the electron, what happens and
how things kind of blow up mathematically. Yeah, and we'll
always struggle to explain the microscopic in terms of ideas
we invented as macroscopic meanings, and there's no guarantee that
we're going to succeed. But when those ideas break down
is when I think we get the greatest insights into
what's really happening down there. We know that there's not
(38:03):
really particles, they're not really ways, they're weird quantum fluctuations
and fields, and they're not just isolated little dots. And
so that's I think when physics has to confront our priors.
Are assumptions, are basic instincts, and discovery that they're wrong
are when we can make a big step forward in
our sort of intuitive understanding. Well, thank you, Daniel. I
feel like that for the rest of to day, I'm
(38:23):
going to be thinking about naked electrons, naked higsons. This
is all cleared by the Emotion Picture Association of America.
That's right to this rated P for physics, some naked
particles may appear. All right. Well, we hope you enjoyed
that discussion and learn a little bit more about what's
(38:46):
really the charge of the electrons and what's really the
massive things and what happens when you get down to
where things are not normal. That's right, and I hope
that this podcast on renormalization has renormalized everybody else out
there to be an at home particle physicist. Thanks for
joining us, See you next time. Thanks for listening, and
(39:13):
remember that Daniel and Jorge Explain the Universe is a
production of I Heart Radio. For more podcast from my
Heart Radio, visit the I Heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows.
Hey, Orry, remember a few weeks ago when we criticized
Albert Einstein. I remember you criticize Einstein. Well, you know
he added a big fudge factor to his theory just
to make it work. Yeah, it was a pretty big
fudge factor. I guess it was a little bit embarrassing
for the old genius. It was sort of a universe
size fudge factor. Well, you know, it turns out maybe
I shouldn't have been so critical because particle physics has
(00:31):
some fudge factors of its own. Particle physicist shouldn't be
throwing stones at glass theories. That's right, we got some
whoppers of fudge factors. Are they Einstein size? Are they
really big? Well? Does an infinity count is really big?
Does nothing count as really small? I think so. I
(01:06):
am more handy cartoonists and the creator of PhD comics. Hi,
I'm Daniel. I'm a particle of physicist, and I'd just
like to point out that Jorge is not just a cartoonist.
He also has a PhD from a famous university. Thank you.
I'm glad you think it's a famous university, you being
on the other side of the Bay Area. It's famously
the second best university in the Bay Area, even enough
(01:28):
to Santa Clara University. I think that's probably true. But
welcome anyway to our podcast Daniel and Jorge Explain the Universe,
a production of I Heart Media in which we take
you on a tour of all the incredible, amazing bunker
stuff in the universe, from tiny little particles that don't
really spin too enormous galaxies that spin mysteriously. Yeah. We
(01:49):
go from the crazy maybe ideas that physicists have about
the universe to the actual nitty gritty theories that they have.
Because everybody is curious about our universe. How does it work?
What's really happened? The search for truth and understanding is
as old as human consciousness. And here we take you
on some of the last steps and we try to
bring you up to speed to what scientists are thinking
(02:10):
right now. What model is in the head of particle
physicists when they think about a particle. How does a
cosmologists think about the whole universe? Yeah? And are they
right or are they just making it up as they
go along? And doesn't make any sense? And what does
it mean if the universe doesn't actually make sense? Oh? Boy,
now you got me worried. Well, after today's episode, you'll
(02:33):
discover that it's all sort of well. These days, the
universe doesn't seem to make a lot of sense. But
fortunately that's what we're here for, and that's what physicists
are here for, to try to put some order into
the universe. And so today on the program, we'll be
talking about a particular I don't know what do you
what would you call it a whole in your theory
of the universe or a hole in your theory of matter.
(02:54):
It's sort of like a shift in your perspective. We're
used to thinking about particles in one certain way. What
is their spin, where is their mass, what is their charge?
But we discover that didn't really make a lot of sense,
and what we had to do was think about particles
in a totally different way. I see. So when something's
wrong or there's a big hole in it, you just
you just call it need to shift our perspective. That's right,
(03:16):
let's just sweep all that under the rug and then
called the rug our new idea. That's essentially what's happening here.
But that's you know, that's an important part of physics
when you have a model and you push on it
and push on it, you discover it doesn't actually quiet work,
and then you have to accept something counterintuitive, something new,
a new perspective on the universe, but one that actually
does work mathematically. That's right, and so to be on
(03:38):
the program, we'll be tackling the question what is renormalization.
Is it just a fancy physics word for making stuff
up and pushing all the infinities under the carpet, or
are we going to talk about when things will go
back to normal in this crazy world we live in
right now? That's what I was hoping for, or when
(04:00):
I saw the title, Daniel, I would not rely on
particle physics to make things normal. It reveals the bonkersness
of the universe. It reveals how the universe is so
hard to grasp, and we're in this constant journey of
trying to map our understanding of the universe onto the
microscopic to think about these little objects electrons and photons
in terms of quantities that we find familiar, you know,
(04:22):
mass or charge or spin. But it's a struggle, I see.
You have to sort of assume the opposite when a
particle physics is walks in you're like, let's throw normal
out the door. It's buckle up and get ready for
a journey to the weird, because that's where we all live.
All right. Well, this is a pretty interesting idea, and
it has to do with your theories about particles and
(04:44):
matter and that they sort of don't always work or
there's holes about them. Yeah, it's sort of akin to
how if you try to describe particles in terms of
particles like tiny little dots of stuff, that doesn't always work. Right.
We see particles sometimes having produce like waves, right, they interfere,
and so we have a broader sense of these things.
(05:05):
They're not just little dots of stuff. They're these weird
quantum mechanical objects. It can be like waves and like particles.
So that's an example of how you might have to
broaden your concept of a particle. And today we're gonna
have to broaden it again, sort of in a different direction,
because the idea we had about particles carrying these little
numbers with them doesn't actually quite work when you sit
down to do the man. I was just wrapping my
(05:27):
head around that idea. Daniel, you're saying it doesn't apply
or doesn't quite tell me, what's happening in the universe? Yeah,
And you know what we do is we have this idea.
We say, let's give these little dots in space, these labels,
these numbers will say charge mine is one mass of whatever,
spin of a half, and then let's see if it works.
And when you run the numbers and try to compare
(05:48):
it to what we see in experiments, it doesn't actually work.
And it tells us something sort of deep and weird
about what the particles are and what they aren't. Sounds
interesting and I want to know more. But at first,
as usual, Daniel went out there into the wilds of
the internet to ask people if they knew what renormalization was.
That's right, So thank you to everybody who volunteered to
(06:11):
answer a random person on the internet questions. Before you
listen to these answers, think about it. Have you heard
of the term renormalization or would you even know or
guess what it could mean. Here's what people had to say. Um,
maybe something happened to you and you are becoming normal again.
(06:31):
I do not know, no clue. I my guests would
be to bring something back to normal after a change.
I'm not sure when something goes normal again. What happens
if you don't know what any of the words. I
(06:52):
really don't know. It's not a term I've heard before.
My guess is it has something to do with phenomen
of maintaining order in the universe. We've learned something new
about space or um, so, whether that's on a cosmic
scale or a particle scale, and we need to change
(07:15):
our assumptions that go into our equations based on the
nearing side. Well, it seems like some people have the
same idea you did, are going to go back. I
think getting back to normal is probably high on people's
mind right now. But I like, yes or there where
the person just said doesn't mean becoming normal. Well, I've
never been normal, so I can't really speak to them.
(07:37):
All right, Well, this sounds like a normal word, renormalization,
but I'm guessing it has some pretty deep mathematical consequences here.
For particle physics, it comes from the word normalization, and
normalization is just to make something normal. But in mathematics,
when we say making something normal, we don't mean make
it usual or typical, or you know, like when you
(07:59):
were a kid it. What we mean is that we
make it all add up to one or fix it
to some specific number, right to sort of calibrate it
almost in a way. Yes, calibration exactly. And so renormalization
is like, oops, something went wrong and now we need
to do it again. It's like, you know, you thought
you had your spendometer working correctly on your ferrari, and
(08:19):
then it turns out you were going one sixty when
you thought you were only going eighty. So you gotta
recounty account. You gotta renormal make it normal again, make
it normal again, make it the old familiar ferrari or
electric charge that you knew when you were a kid. Okay,
And that's exactly the issue here is that we ran
into a problem when we were trying to calculate the
electric charge of the electron. It sounds pretty basic, isn't
(08:43):
the electron something we've known for a long time and
know what the charges? You think? So, right, it's sort
of like how we defined electric charge. It's like, you know,
Ben Franklin or whoever you know first identified this as
moving charges. Define charges to be plus and minus, and
that's where the electron charts comes from, right. It's the
carrier of the minus one charge, is like the definition
(09:04):
of what the charge is, right right? Oh, I see,
So an electron has a negative charge one, it's sort
of the definition of charge. What are the units electronus? Well,
you know, it's defined in terms of cool ombs, but
it's a crazy number in terms of cool ombs, and
so we just in particle physics, we'd like to drop
all the units and redefined everything, and so we just
call it one e like one electron charge. That's the
(09:27):
unit alright, So it's kind of like the standard. It's
kind of like the standard. But the problem is if
you say, okay, I have a little particle and I'm
gonna put a minus one charge on it, and then
you put that into an experiment and try to measure
the charge of it, you would actually measure zero. Like
you shot other electrons at it, you would measure almost
(09:48):
zero charge. It sounds like a big area here. You're
expecting minus one and you got zero. Yeah. So the
electron can't have charge minus one because if it did,
we would measure zero. And the reason is that the
electron is never just by itself, right, It's not like
a whole universe populated by just an electron. Instead, the
(10:08):
electron is surrounded by space and space is never empty.
We've talked to this podcast a lot of times how
space is not just the backdrop of the universe. It's
this crossing quantum mechanical weirdness that can do stuff we
don't understand, like expand and wiggle and stretch, and their
deep theories about space that people are working on. We
(10:28):
talked about Steve Wolfram's idea about space and quantum foam
space and like it's a huge question marks empty space
is not empty. Empty space is not empty space. Sometimes
that space out when I think about it, but there's
a lot of it. That's the one thing that's still true.
There's something to it, and somehow that's affecting what we
measure about the electron. Yeah, because space is filled with energy,
(10:52):
and energy can turn into virtual particles, particles that pop
in and out of existence really briefly. And when that happens,
usually you get a pair of the particles like a
plus one and a minus one that pop out together
because it has to balance out, like you can't just
introduce more negative charge into the universe. You kind of
have to balance it out. That's right, There still follows
some rules, right, Virtual particles are not a total free
(11:14):
for all. They still have to observe the rules of
the universe, and one of those is that the pluses
in the minuses have to balance out. And so essentially
any electron is surrounded by a bunch of positive negative
charged particles. So then the electrons field, the electric field
that it creates, it pulls on the positive part of
those virtual particles, and it pushes on the negative part
(11:37):
of those virtual particles. But they don't exist. They do exist, though,
they do exist briefly, right and constantly. It is a
frowthing swarm of these particles. And so what it does
is it like polarizes the vacuum. It pulls the positive
part of these virtual particles closer, and it pushes the
negative ones away, and it has the effect of essentially
(11:57):
shielding the charge of the electron. Oh, I see, But
they don't exist, though, do they They actually pop into existence?
They do exist, They actually do pop into existence. Yeah,
And you know, this is the kind of effect that's
very familiar. Like the reason you can't use your cell
phone inside an elevator is that electromagnetic field can't penetrate
very well through metals because metals are filled with little
(12:20):
charge carriers electrons, and when electric field passes through metal,
the electrons will like rearrange themselves to cancel out any field.
It's called a Faraday cage. Okay, So then if you
have an electron, it's gonna pull these virtual plus particles
to it, which then cancel it it out. Is that?
What is that kind of what you're saying? Yeah, but
these per virtual particles are also like possetrons or are
(12:43):
they you know, imaginary? Are they actual like you know,
ions or muans or what are they? They're actually all
kinds because you can have any kind of virtual particle.
You can have virtual particles that are pairs of electrons
and positrons, like you said, you could also create muons
and anti muon. You can create quarks and antiquarks. You
can create anything you like out of the vacuum as
(13:05):
long as you observe the conservation laws, and then most
likely you're going to create the lowest mass particles. So
usually you're going to get things like electrons and positrons. Okay,
but they're sort of virtual because they're popping into existence
and popping out of existence. But there's enough of them,
and there's a constant popping in and out of existence.
That effectively they are real. They count as if they
(13:26):
were there. And so what happens is that you you
shield the true charge of the electronic it reduces it.
It like screens the charge sort of like if you
want to know how cold it is in your freezer,
but all you can do is measure on the outside. Well,
you're not really measuring the true temperature inside your freezer, right,
You're shielded by all the insulation, and so that's essentially
(13:46):
what's happening here. So then if all electrons then are shielded,
how do they even work? Yeah, Like if I have
two electrons in space and they're shielded, then they wouldn't
repel each other. That's true if electrons charge is actually
minus one, But it's not. That's the kicker, that's the renormalization.
The charge we measure is minus one. Right, electrons do
(14:10):
repel each other. You're right, electricity is real. Right, we're
not repealing electricity today in the podcast, which is canceled
the electricity exactly. But what we've discovered is what we've
been measuring for more than a hundred years is not
the true charge of the electron. It's this shielded charge.
We're measuring the electron on the outside of the freezer.
(14:30):
That charge is minus one. What is the electrons true
charge behind all that shielding? That was the new question. Oh,
I see it's in the freezer, and we didn't really
know how cold it is or how electrically charge it is. Yeah,
and we sat down to do these calculations. We realized, wait,
isn't there a big effect from this freezer, from this shielding,
from the screening, from all these virtual particles. And people
(14:52):
started calculating. The realized, yeah, there is. So if electrons
had charge actually minus one, we should be measuring zero
charge experiments, but obviously we're not. So they went back
and they said, how much do we have to dial
up the charge of the electron before we get a
measure charge of minus one to extrapolate through this cloud
(15:14):
of particles and say, what's really going on in there?
So what we see of the electron when we measure
as its charge is what we measure through the installation,
this virtual installation that that you're talking about. That's right,
and so the question is what's its true value inside?
That's right. Let's pull back a layer of reality and
say what is really happening. Okay, it's not just minus too.
I'm gonna guess you know it's gonna be totally unsatisfying
(15:36):
and frustrating, like usual with particle physics. Great, well, I'm
looking forward to Daniel. So let's get into it, and
what does a real charge means of the for the
electron and for mass and for the entire universe. But
first let's take a quick break. Al Right, So an
(16:06):
electron doesn't have the charge of an electron apparently depends
what you mean by an electron. Up is not up,
and the electron doesn't have electron on an electron. No,
it's really it's about definitions, and that's where we're gonna
end up today, is talking about like what it means
to be an electron. Because the thing we measure you
call that an electron. You know, some weird quantum dot
(16:26):
with all of its shielding and fuzziness and virtual particles
all around it. That thing has charged minus one. But
if you try to penetrate that cloud and say this
bit at the core, the true electron, the fundamental electron.
Because we're interested in understanding the deep nature of the universe,
not like the effective, messy, sloppy things we can actually measure.
(16:48):
We want to, you know, penetrate all the way in
and see what's really happens to see it's not I
guess celebrity. You know, they're surrounded by all this hype
and people and you never know really who they are
on the inside. And so that what we're doing today,
we're peeling back the layers of stuff to get a
real sneak pick at the electron inside. That's right, So
what what is the real charge in of the elector
(17:08):
when you get through the electrons entourage? What you discoverage
is to make the measure charge minus one, you have
to set the true charge. And particle physics we call
this the bare charge, like an electrono by itself to
minus infinity, like what the bare minimum? You know, just
(17:30):
a small thing like minus infinity. I know. I remember
learning about this and thinking, oh, renormalization. Okay, so you
gotta adjust the charge of it's going to go down
to one and a half or two or whatever, and
then discovering you gotta minus infinity. What that doesn't even
make any sense? That's great. You can't call that renormalization.
(17:52):
How can how can you say that an electron has
a negative charge of negative infinity. What does that even mean?
It's hard to understand, and you know mathematically what happening
is that the more the electron is charged, the more
it gets shielded. Like, the more powerful its charges, the
more it polarizes the vacuum around it. If you crank
it up to minus two, you don't get much measured charge.
(18:12):
You've got to really crank it up incredibly just to
get any measured charge because it works against you. There's
no limit to these virtual particles. I mean space is
full of them. And then what does it mean, like
whenever you discover an infinity and particle physics, space is
full up to infinity, Like space has an infinite number
of virtual particles all the time everywhere. Yeah, an infinite
(18:34):
number of virtual particles. That is true, it's not an
infinite amount of energy. So there's an infinite number virtual particles.
The number of them increases as their energy decreases. So
it's rare to get a high energy virtual particle or
a high mass virtual particle. It's totally common to get
an almost zero energy particle. That the smaller the energy,
(18:55):
the higher the probability and so as that goes to zero,
you literally get infinite numbers of particles. But anytime you
get infinity in a particle physics, like you say, okay,
this particle has minus infinity charge, that tells you you're
doing something wrong, not just this particle. Imagine it then
applies to all particles. Yep, this does actually apply to
every single charge particle in the universe. That's right. So
(19:18):
that's a pretty big problem. And you know, we should
not be throwing stones at Einstein when it comes to like,
you know, by making big corrections to basic facts about
particles in the universe. So so my intuition tells me
that it's it seems implausible, if not impossible, for every
particle in the universe who have a infinite charge. So
(19:38):
I guess, step me through what's going on, Like, where
does our model of the universe break that we have
to do this fudge? If it is a fudge, No,
it's it's sort of a fudge. But what you have
to do is renormalize your theory of a particle, your
idea of what a particle is. Like we've been thinking
about electron as a tiny individual dot, like a basic constituent.
(19:58):
You know many lego brick out of which stuff in
the universe is made out of, right, But instead that
doesn't physically make sense. It has to have negative infinity charge. Instead.
You need to think about the electron, not by itself.
The whole concept of an electron only makes sense together
with this virtual swarm of particles. So that's not separate
from the electron. It's not just an electron in the freezer.
(20:21):
The freezer is part of the electron. Oh I see.
Just gonna pull back your definition and ignore what's inside
of the freezer is kind of what you're saying. That's right.
It's like you say, hey, I'm not going to clean
up my living room. Messiness is my new living room,
and that's just you know, this is how I live now.
This is the new clean. Right, that's a renormalization. Oh
(20:42):
I see, okay, God, messiness is a new clean, Infinite
particles is a new emptiness, and negative charge isn't a
new minus one? Right, and space is the new not nothingness.
Trust me, this all makes sense. Okay, got it? Got it?
So I think that's kind of what you're saying is
just ignore what's inside of the freezer and just don't
(21:04):
open the freezer. Don't even think about what could be
in there, growing you know, who knows what. Just lock
the freezer, throw away the key, and just deal with
the freezer. Yeah, And the thing to remember is that
when you get an infinity to the answer to a
physics question, it tells you that you're asking a question
that doesn't really make sense or that isn't really logical.
Here is another simple example. Say you wanted to know
(21:26):
what's the force on my head from all the stuff
in the universe that's on my left. Well, the universe
is infinite, then there's literally an infinite force of gravity
and electromagnetism and all that stuff on your head from
that side of the universe. Now there's a whole other
side of the universe that also has an infinite force
from the right side of the universe, right, and and
(21:49):
they cancel each other out to get basically zero force.
So asking that kind of question just means there's an
artificial distinction that you've introduced. The infinity comes only because
the question you're asking doesn't really make sense, like what
is the left side of the universe or the right
side of the universe. In the same way, trying to
separate the electron from the rest of the universe and
(22:09):
asking what is its charged all by itself, that doesn't
really make sense. You have to think about the electron
as part of an interaction. I mean, the electron has interactions.
It It sends off photons constantly. It's not doesn't really
make sense to sort of draw a dotted line just
around it and say, only think about this bit. I
think I understood that a negative infinity amount. I feel
(22:33):
like what I feel like you're saying, that's just ignore
this little weird fact and just not think about it
and just go with the flip. No, don't ignore it,
but just redefine the question you're asking. It's just like
in Douglas Adams. You know, if you ask a question
and get a nonsense answer, you have to go back
and think about maybe I should ask a better question.
In this context, asking what is the charge of the
(22:53):
bare electron doesn't really make sense because that's not a
physical thing. You will never have a bare electron. There
will never be an ale tron without its entourage. That's right,
only in a universe in which there is only electrons
and there are no interactions at all, which can't exist.
So I guess you're saying that what's inside the freezer
doesn't matter because we'll never open the freezer, or they'll
(23:15):
never be something without a freezer, that's right, And we
can't open the freezer. So even though you would predict
that there's negative infinity charge inside of the freezer, that's
probably not what's going on because we don't really know
when we never will open that freezer. Yes, except we
have ways to partially crack open the freezer. Yeah, all right,
(23:36):
because this is a virtual cloud of particles, right, and
we can penetrate it. Like if you shoot an electron
at another electron really hard, it will get through more
of that virtual cloud. Then if you shoot an electron
at it really gently. And so it turns out that
the harder you shoot one electron at another, the stronger
(23:56):
the charge you measure. So the charge of the actron
depends on the energy of the particle you're using to
measure it. So the electron doesn't just have a charge
of minus one that you measure or minus infinity inside
the freezer. The answer depends on how much you've cracked
(24:17):
open the freezer, how much the entourage gets out of
the way, or something. Yes, so you can get through
this virtual cloud of particles partially. You can never get
all the way, but the more you probe in there,
the stronger the charge of electron that you measure. So
it's sort of is like a real physical thing. You
can poke at the freezer and kind of take a
peek inside, and it does look like it's almost negative affinity.
(24:39):
Is that kind of what you're saying. Yeah, you can
never get to negative infinity, but the higher energy you
probe with, the stronger the charge you measure. And so
that's also sort of like, you know, a bit of
a brain scramble. You're used to thinking of the charge
of the electron as a basic fundamental constant, right, Well,
it turns out it's not constant. It depends on the
energy at which you're probing the electron. So the charge
(25:02):
of an electron is not then one of the fundamental constants. No,
it's not, or basic constants not. And we talked about
this on a podcast recently, how there's a different constant.
It's called the fine structure constant that includes the charge
of the electron and the speed of light and planks
constant because those things themselves are not actually fundamental constants.
(25:23):
Only in combination the ratio especial ratio of those things
are fundamental constants. I see. So I guess what you're
saying is that if I shoot an electron with a
fast enough electron, I would maybe measure it's charged to
be negative infinity. Yeah, it had to be infinitely fast
electron that you're shooting. The faster the electron that you're
using in your gun, the stronger the charge you measure
(25:46):
on the electron. Well, I feel like we're throwing infinities
all around, So why not let's just throwing infinite a
number of infinitely fast electrons. Now there's just no rules, right,
It's like whatever anything can happen doesn't even matter. All right. Well,
that that's pretty wild to know that the electron has
this kind of hidden and maybe infinite charge. And so
(26:07):
I guess the question is, how does that affect what
we thought about the universe or how we look at
things like mass or you know, effic goes to me
and all that stuff. So let's get into it, But
first let's take a quick break. Al Right, So apparently
(26:34):
the electron has possibly a negative infinity charge if you
can get to it, if you can get past a
cloud of virtual particles that surrounded and protected and kind
of shielded from the rest of the universe. And so
that's a wild concept, Daniel. Now, what doesn't mean about
what we know about the electron? Well, it's not just
the electron. Remember, all charged particles have the same property
(26:57):
that they shield themselves. And what we're measuring is really
the variable strength of the electromagnetic interaction. And the higher
the energy you have, the stronger this interaction is. And
so what it tells us is that the particles by
themselves is unique. This bare particle, the stripped of all interactions,
is not a physical thing that we should be thinking about.
(27:18):
And we need to renormalize our idea and think about
the particle together with its entourage. That really defines who
it is. Because you know, if you met a celebrity
without their entourage, they probably wouldn't seem that famous either,
would they. It seemed normal and down to earth. I
don't know, you tell me you've met me in person, Daniel,
what is that? I had to fight my way through
(27:39):
your entourage? Um? All right, So so that's kind of
what this renormalization means. It's like kind of like getting
used to the entourage of particles, and it doesn't just
apply to the charge. It turns out that most of
the fundamental characteristics of the particles have this same property,
that they have a measured value and then a weird
(28:00):
it's sometimes non physical sort of bear true value. I mean,
like some of the other quantum charges like color and
spin and things like that. Just like that. Yeah, the
strong nuclear force also has its strength vary with the
energy of the particles that are shooting at it. But
I think one of the weirdest things is the particle mass.
(28:20):
Like we think about mass and sort of like a
defining characteristic of a particle, like what's the difference between
an electron and muant while a muan is heavier, right,
And we identify particles by their mass, But it turns
out that what we measure, and we measure the mass
of the particle is not actually like the true fundamental
mass of the particles, not the mass the particle would
(28:41):
have if it was all by itself in the universe
with no interactions, right, because instead of virtual particles that
it interacts with, it interacts with something else, the Higgs field. Right,
that's right, all particles moving through the universe are interacting
with all the quantum fields that are around them, and
what happens when they interact is that you know, those
fields amid little particle for them to interact with. And
(29:01):
so you can imagine like an electron flying through the
universe and it can emit the Higgs boson and then
it can reabsorb that Higgs boson. That's effectively what's happening
when it's interacting with the Higgs field. It emits a
virtual Higgs boson and then re absorbs it. And it
can do that, or it can do admit to Higgs bosons,
or that Higgs boson can split into other particles and
(29:23):
then come back together. There's millions of different possible things
that could happen as an electron is moving from A
to B. And so we've talked before on the podcast
about how the Higgs boson gives particles mass, and we
say this this field that fills the universe, and interacting
with that field gives those particles masses. But we sort
(29:43):
of dot dot dotted over that critical bit, like how
does interacting with a quantum field give a particle mass?
What does that mean? Right? Well, there's the analogy of
like moving through a crowded party or something, right, Like
you're trying to move, but the field is throwing particles
at you, and you're throwing particles at and that's kind
of what inertia sort of is. That's exactly right. And
(30:04):
if you want to go from A to B and
you talk about a particle having mass, then it takes
energy to speed it up as it's going from A
to B, or it takes energy to slow it down,
and it turns out that's inertia, right, And that can
be exactly modeled as a particle interacting with the field
because as it goes along, you can admit a particle,
you can absorb a particle. There's all these complicated interactions
(30:25):
that can happen, and those interactions have exactly the same
effect as if you just gave a particle inertia sort
of by hand. Those interactions all add up to create
this effect that we describe as mass. Like it again,
this is a separation between like our macroscopic observations of
stuff and the microscopic explanation for what's really happening, and
(30:49):
the macroscopic thing were familiar with is like, hey, stuff
seems to have inertia. You know, you push on a
heavy rocket, takes a while to get it going. You're
downhill from a heavy rock, you better move out of
the way because it's hard to slow down, right, And
that macroscopic property turns out to be explained by all
the little particles inside it interacting with the Higgs field,
with virtual particles, with virtual particles exactly, that's the key,
(31:12):
are you saying, sort of like all particles, and it's
not just their electrical charge, You're saying their mass. It's
also kind of insulated by these virtual Higgs boson clouds.
I'm saying that what we call an electron that has
mass is actually an electron with a swarm of Higgs
bosons around it. That's what it means for an electron
(31:32):
to have mass, is that it's sort of clouded by
the Higgs field. And so an electron moving through universe
with no Higgs field would have no mass. Right, So
what we call the electron is not really just the electron.
Is the electron surrounded by this swarm of virtual particles
it's constantly interacting with. So in the same way we
renormalized our concept of the electron as the electron surrounded
(31:55):
by its virtual screen of particles shielding its charge, we
all also have to include for the electron when we
think about its mass, we have to think about this
virtual cloud of particles it's interacting with, because that's where
it gets. It's like, it's like kind of like what
you're saying is that all of these quantum fields and
the universe are all sort of connected to each other,
(32:15):
and so you can't really talk about one thing because
it's it's all connected everything. Nothing can exist on its own.
That's right. We've got pretty spiritual pretty quick there. Man.
Maybe we're connect Man, it all is just a renormaliz
past that do be over here, man, I want to
(32:35):
be normalize. Yeah, exactly. Got to smoke your banan appeals.
And you've got to understand that these particles, they're not
on their own. They're just fluctuations of quantum fields, and
these fields are all interacting with each other, and so
it doesn't really make physical sense to say, what is
the mass of this one little particle, what is the
charge of this one little particle. You've got to think
about it together. But you're sort of saying that particles
(32:57):
don't have mass without the Higgs field, right, that's exactly right.
If there was no Higgs field, these particles would all
have zero masses. And so the bare mass of these
particles in the limit where you think about the non
interacting is zero. All the particles in the Standard model
except for the Higgs boson, have bare mass of zero,
and they all get their masses through this virtual swarm
(33:18):
of craziness. And it's not just actually through interacting with
the Higgs. Like the electron also gets more mass because
it emits photons. I know, that's especially weird because photons
have no mass. Right, in addition to interacting with the Higgs,
they get mass from photons. That's right, they get mass
from photons. And now, if there wasn't the Higgs, the
electrons would have no mass. But because they're the Higgs,
(33:39):
photons can add mass to the electron. It's like multiplicative,
like they make it have, you know, they multiply its
mass by a certain factor. If it was zero would
stave zero. But since the electron gets some mass from
the Higgs, the photons boosted. Remember mass is also related
to energy, and in a sense, what we're talking about
is how the electron has a lot of self energy.
It's constantly emitting and absorbing a swarm of photons, and
(34:03):
those contribute to its effective mass, which is what in
the end we measure. We only measure, you know, physical things.
We can't actually measure true things about the electron. If
it was all its only in the universe. I feel
like you guys wanted to call it naked charge, but
you were, but you still have backed down. You're like
to naked charge, but we can't. It's called naked charge.
It's called bear charge, and thus confusing everyone because they're
(34:24):
like bears. What do you mean, like like a bear? Exactly,
it's one of the bare necessities, you know, exactly, all right,
But then does the electron then have a constant mass
or does it also vary like it's charge, It also varies. Yeah,
all these quantities actually vary with the energy you're using
to probe it. But last time we talked, that's in
(34:46):
the mass of the particles were constant in the universe. No,
you're totally right, And what we actually mean when we
say those constants is we mean the strength of the
interaction with those particles and the Higgs field. That's what
controls the mass but the mass of you measure and
individual experiment does depend on the actual energy of that experiment. Wow,
(35:07):
so now we also have to redefine mass mass um
doesn't exist. It seems it's inside the freezer. Yeah, everything's
inside the freezer. This is something that helps you also
understand how the universe could have been very different in
its early years, because in the very early moments of
the universe, Remember, things were hot and dense and nasty,
and all the particles had a lot of energy, and
(35:29):
all these forces charge, and the strong nuclear force and
the weak nuclear force, all of them depend on the energy.
And so back in the early days of the universe
we think that maybe all the forces had the same strength,
and that what's happened since then as things cool down
and things got slower and calmer, is that these things
have different like variations with energy. You know, one of
(35:51):
them drops really quickly as things go to low energy,
another one drops really slowly. But back in the early days,
things were glorious and unifisity. Back then, thanks are normal
Then we denormalize kind and now we've got a renormalize.
You got a normalize. And but I have to say,
none of this makes me feel normal at all, Daniel,
you just told me that the electron doesn't have a
(36:14):
charge and it doesn't have mass, so it's not easy
also for particle physics to accept this. There are a
lot of years when after people made this discovery that
you have these weird infinities in the theory, that they thought, well,
the theory must just be wrong, right, there must be
a problem with the theory. And then people realized, oh, well,
you know, you just redefine what you mean by an
electron and then you don't have to worry about those infinities.
(36:35):
And a lot of people objected. They were like, you
can't just do that. You can't just define your living
room to be clean now, but if you don't have
any better ideas that you can. But but but it
turns out you can. If yours is the only house
in the universe and you're the only one person living there,
you didn't define it however you want. But then there
was a guy Ken Wilson, who is sort of an
(36:56):
underappreciated genius, who sort of made a deeper point about
the whole nature of the universe, and he said, you know,
nothing is really constant. Everything depends on energy the physics
you measure depends on the energy you're using to measure it,
so it's totally natural for things to vary. In fact,
the mistake was to expect anything to be constant. So
he said that the grandest renormalization of them all. I see. Wow,
(37:20):
he like dropped the mic. He's like, bam, I just
redefined normal exactly. He redefined what success was. All right, Well,
I think it's pretty interesting and mind blowing to like
think about what happens when you actually get down to
that level. You know, when you try to get down
(37:40):
to the zero size of the electron, what happens and
how things kind of blow up mathematically. Yeah, and we'll
always struggle to explain the microscopic in terms of ideas
we invented as macroscopic meanings, and there's no guarantee that
we're going to succeed. But when those ideas break down
is when I think we get the greatest insights into
what's really happening down there. We know that there's not
(38:03):
really particles, they're not really ways, they're weird quantum fluctuations
and fields, and they're not just isolated little dots. And
so that's I think when physics has to confront our priors.
Are assumptions, are basic instincts, and discovery that they're wrong
are when we can make a big step forward in
our sort of intuitive understanding. Well, thank you, Daniel. I
feel like that for the rest of to day, I'm
(38:23):
going to be thinking about naked electrons, naked higsons. This
is all cleared by the Emotion Picture Association of America.
That's right to this rated P for physics, some naked
particles may appear. All right. Well, we hope you enjoyed
that discussion and learn a little bit more about what's
(38:46):
really the charge of the electrons and what's really the
massive things and what happens when you get down to
where things are not normal. That's right, and I hope
that this podcast on renormalization has renormalized everybody else out
there to be an at home particle physicist. Thanks for
joining us, See you next time. Thanks for listening, and
(39:13):
remember that Daniel and Jorge Explain the Universe is a
production of I Heart Radio. For more podcast from my
Heart Radio, visit the I Heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows.
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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