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July 18, 2019 42 mins

Find out about the Weak Force on today's podcast with Daniel and Jorge.

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Episode Transcript

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Speaker 1 (00:08):
Hey, hey, you have strong opinions about naming things, didn't you.
I just don't like kids when things are named in
a very confusing way, or where the name actually confuses
you instead of making things clear. All right, Well, then
I have a bit of a personal question. How did
you pick the names of your kids? Not through physics,
for sure, that's definitely did not. There's not one called strange,

(00:32):
one called charm. They're both strange and charming, for sure.
That's a linear superposition. There is physics there. They are
definitely quantum and delete for sure. Our son was named
my wife had had a dream, and that's how she
came up with the name for our son. She just

(00:53):
came up with the name in the dream. And my
daughter is named after a Jane Austen character. Wow. Alright,
so both bired by mental realms outside of the physical world.

(01:19):
I am more handmake cartoonists and the creator of PhD comics.
I'm Daniel. I'm a particle physicist, and I'm a connoisseur
of all jokes physicals ee, strong electric and even weak
ones and banana forces. Of course, that's right, And of
course the mysterious banana field that feels the universe and
it is mostly concentrated around Jorge's head, and together we

(01:40):
are co authors on books and other projects. But this
is our podcast, Daniel and Jorge Explained the Universe, a
production of I Heart Radio, in which we take you
on a tour of all the weird, crazy, amazing stuff
in the universe and try to explain it to you.
So you go away going, wow, that's kind of cool.
I never understood that before. All these strong and amazing

(02:02):
things and even the weak but significant things in the
universe that maybe every once you know about. That's right.
It's a forceful exposition of all the fascinating things about
the universe. Oh man, now you're just forcing it. I
think that's right. Well, you know, my my joke, force
is pretty weak. But forces themselves are sort of a

(02:22):
weird thing. It's like, forces are something that physicists you've
even had a hard time grappling with over the centuries. Well,
it's something that's really intuitive. I think. You know, as
a little kid, even as a baby, you sort of
get the idea of force, right, Thanks pushing you, thanks
pulling you, gravity, pushing you down. Yeah, but I think
your intuition is misleading. I think most people think of

(02:43):
a force as something as a push, right, something that's
touching you. Somebody comes up to you, pushes you over,
you fall over, you move your role or whatever. So
I think most people think of forces as touching. The
really weird thing about forces is when they can act
without touching, right, When they can, like when you see
a mad levitating, it seems almost like magic, right, because

(03:03):
this this, these two things are acting on each other
without actually touching each other. Yeah, it's weird. And so
today we'll be talking about one particular force out of
all the forces out there in the universe, one that
is maybe not the strongest one, but that led to
some amazing discoveries. Right, that's right. It's not the most
powerful force, but it did give us some amazing hints

(03:26):
into the way the universe works. So it's weekly powered,
but plays a strong role in the sort of overarching
drama that is physics. Yep, it's a four sets inside everyone, right,
it's inside of me, inside of you, inside of everyone
listening to this podcast. That's right. It's everywhere in the universe,
and it plays an important role in how we live
and how we die and how we power ourselves. So

(03:47):
to be on the podcast, we'll be talking about the
weak fours? Weak fours? Are you just trying to add
some drama to it because it needs some panash? It
was a little anti climatic. Did you say I thought
you might go with weak nuclear force because nuclear gives

(04:08):
it some sort of like edge of mysteriousness. Right, the
weak quantum? No of the week? Black holes pilate on.
Let's just give him multiple hyvingated names the week, true, Guadalajara,
Montre exactly. Um, that would be a lot more fun. No,
the weak force is really amazing, it's fascinating. Yeah, it's

(04:30):
one of the four fundamental forces in nature. Right, there's
only four of them? Yeah, well, spoiler alert turns out
there's three. You eliminated one like Pluto just got deep declassified. No. No,
that's the goal of physics, right, is to not have
four forces. We don't want to say, hey, here's how
the universe works. There are four totally weird, separate rules

(04:53):
about things, how things can push and pulling each other.
We we think, we hope, we want to explain the
universe in terms of one force. So the story of
physics so far is look around you see all the
weird thing that's happening in the universe and try to
describe them all in terms of the smallest number of things,
the smallest number of forces. So yeah, the goal is
to sort of take things off the list and describe

(05:14):
everything in terms of just one thing. So you're saying,
there used to be only four forces in the universe,
and then phasics killed one of them and or married
two of them, and now there are only three fundamental
forces in the universe. Yeah, well, this the drama is
even more because we suspect that in the first few
moments after the Big Bang there was just one force,

(05:37):
but then as the universe cooled, we think they've broke
up into all these different forces. And what we're trying
to do now is sort of re run that backwards
and understand, like, can we bring these things together. Can
we understand these things in terms of one big picture?
How do we bring marry these things back together? You know,
it's like a it's like a universal divorce early on,
and we're trying to bring the couples back together and

(05:58):
show them how they can work together. You're trying to
bring the band back together. Basically, it's like the Beatles
broke up, and you know, we enjoyed their individual work.
But come on, guys, yeah, that's a great analogy. Wouldn't
you like to just describe the Beatles instead of having
to describe all four members of the Beatles? Right, That's
exactly what we're trying to do. We're trying to show
you that, you know, the drums are not interesting on

(06:20):
their own, They're just part of a larger harmony. Right.
They make much more sense when you understand them in
terms of the guitar parts and the vocals which come
together to make this amazing beautiful music. Right. Yeah, the
physics of the Beatles, that will be the next exactly.
So today we're gonna show you how Paul and John
were actually the same person. Spoiler alert, they were the

(06:42):
same person. That's right. And ringoes an alien. Everybody knows
ringos an alien, right, all right? So the week nuclear
force and so that's uh, it's not the most popular force.
You know, most people know electromagnetism and gravity. Right. It
is part of the forces, isn't it. Yeah, maybe it is.

(07:04):
Maybe it's the ringo of forces. It's sort of overlooked,
and uh, you know, dismissed, but in the end fundamentally
important to making things work. Just like Ringo, you kept
going to the harmony together exactly without the beats together,
he wouldn't have a good song, That's right. Who ever
heard a good pop song without without without a drum line,
without Ringo? All right? So we were wondering it is

(07:27):
kind of the lesser known maybe of the forces, and
so we were wondering how many people out there knew
what the weak force was. Yeah, and this is one
of the times when I really had no idea what
to expect. Had everybody heard of the weak force and
they We're going to spout off some interesting physics about it,
or are they going to get a bunch of blank stairs?
So I was pretty curious, and so as usual, Daniel

(07:47):
went out into the street and as random strangers if
they knew what the weak force was. And so before
you listen to these answers, think a little bit yourself.
If someone approached you on the street and wearing sandals
and supporting a beard, if they asked you randomly what
the weak force, You're given away my disguise, man, and
I'm gonna have to wear a completely different disguise when

(08:09):
they'll throw them off. They like, you can't be Daniel,
I can I can't seat your toes. So if you
were asked this question, you would you know the answer
to it. Here's what people had to say. Yeah, has
kind of governs radioactive to ka most particle stuff. I
guess I'm not heard of the weak nuclear force. Have
you heard of the strong nuclear force, the medium nuclear force,

(08:32):
the super weak nuclear force? I made most of those,
though we nuclear force not as well, but I've heard
of it. I'm not sure. No, I've not heard of that. No,
the m R I am measures in a clear force,
and then you can know that's that's one of the
four main types of forces in physics, not just in physics,
in the universe right in the universe. Sure, it's kind

(08:54):
of it's a kind of part to strong nuclear force.
Why do we have it? What is it important? Or
what does it do? Has something to do with how
adams are together? I don't know exactly alright, So not
a lot of yeses. I got a lot of blank
looks on this one, that's for sure. Well, some people
most people said no, they've never heard of it. But
somebody actually said that it's related to the radioactive radio

(09:15):
activity radioactive decay, Yeah exactly, and somebody even understood it
was like connected to particle physics experiments we do in Geneva.
So a hundred bonus points to that because your office
made another physics professor that was me with disguising my
own voice, asking myself a questions. Spoiler alert. They're all
you always every episode. I'm just amazing and impressions right now,

(09:39):
you know what one of my UM career goals is, please,
speaking of which is um? Do you ever read The Onion?
They have this fantastic people in the street section with
ask people ridiculous questions and every week they have the
same four pictures and they just give them made up
names and jobs, you know, bone crusher or like you

(10:00):
keyboard tester or something. My career goal is to get
my face is used on the Onion. Is one of
those people on the street saying something dumb. But I've
actually written to the Onions several times volunteering, but never
heard back. Please use my picture exactly, please make fun
of me. Every week? Do they write back or they
just ignored it? No? No, Unlike other Internet celebrities, they

(10:21):
did not respond to my cold call. We'll keep trying, Daniel,
there's always hope, all right, I will. So, yeah, somebody,
most people didn't know what it was, and so it
would Did that surprised you. I mean, it's not something
that is usually covered in you know, high school physics.
Even it didn't surprise me because it is a bit esoteric.
And also it's not something people experience. You know, people

(10:44):
experience gravity, they all know what it is. They have
to understand it, they have an intuitive sense of it.
People experience electricity, right, We've all been shocked by static electricity.
People experience magnets, right. But people don't interact with the
weak nuclear force very much. You don't really see its
conto quince is directly. You can't tell the difference between
it and something else the way you can tell the
difference between gravity and magnetism. Right. Yeah, Well, there's very

(11:08):
a couple of things about it. First of all, it's
a force, and second it's weak. That's right, It's really
really weak, like compared to electromagnetism and the strong nuclear force,
it just is not very effective. And and one way
to understand that is to think about how particles interact, right,
like when you touch something or when you bounce against something,

(11:29):
that's all done with particles. That's particles pushing against each
other or interacting with each other. I mean, the particles
in my finger are interacting with the particles in the
table and so that and they're pushing against each other,
that's right. And that's mostly using electromagnetism because it has
to do with the bonds and the electrons holding the
atoms tightly together and making this like you know, chain
link fence of atoms that your finger can't pass through.

(11:53):
But there are other particles, right, And that's because all
the particles in your finger and all the particles in
the table feel electromagnetism, but they're our particles that don't
feel electromagnetism, like this mysterious particle called the neutrino. The
neutrino doesn't feel electromagnetism, and it doesn't feel a strong force,
and it has almost no mass or it hardly feels
any gravity. The only way it interacts is through the

(12:15):
weak force, and so it's a good lens for figuring
out like how weak is the weak force? Yeah, we
had a whole podcast episode about neutrinos. And we sort
of talked about how, you know, the forces are sort
of like social media channels. You know, there's Twitter, there's Facebook,
there's Instagram that you can interact with people, but some
people don't use some of the don't use Instagram, where

(12:36):
they only use Twitter, or they only or they or
they use all three. And neutrinos are like that, they
only subscribe to this one very lightly used social media
channel and so they hardly interact with the friends that
it's the friends store of media channel, the original And
so that's why neutrino can pass right through you, and
a neutrino can pass right through the Earth right. We

(12:56):
do these experiments where we look at neutrinos from the
Sun and we use the entire Earth as an instrument
to try to get the neutrinos to interact, but most
of them fly right through the entire Earth without interacting.
And if you had to say, like how thick a
wall would I have to build to block neutrinos, Well,
neutrinos can fly through a light year of lead and

(13:17):
have a fifty percent chance I'm getting through. So I
mean it's it's hard to even fathom, like how big
a wall you would have to build to effectively block neutrinos.
And the reason is that the weak force is so
weak that every time the neutrino near something, it rolls
a die and the dye has to come up just
right for it to interact. Most of the time it
just ignores it. Oh wait, so all right, so we're

(13:41):
getting into what is the weak force, and you're saying
that it is super weak, and you're saying that it's weak,
not because it's just the weak force, but it's it's
just less likely to interact with you. That's exactly what
weak means, right, that it has a smaller chance to interact.
Right that you shoot these two things against each other
and will less often have an interaction. But when they

(14:02):
do interact, the force that you actually feel is also
weak or not. Oh, I see what you mean. No,
the magnitude of the force is not effected. It's how
often it happens. It's how likely it is to happen
when it interacts with the nucleus. For example, it bounces
off and goes in the other direction. It's not like
just slightly deflected. It's just that it doesn't happen very often.
It passes right through most of the nuclei without doing

(14:24):
anything and just ignores the last. But in terms of magnitude,
like when it does interact, it is as strong as
the other forces. Yeah, that's a really good question. I
never really thought about it that way. It's just a
question of whether it interacts. The strength of the force
reheally determines whether it's interacting, and so for example, you know,
the strong force is really really strong. There's a lot
of energy in that interaction, and so it's going to

(14:47):
interact with everything else that feels it. Electromagnetism is a
powerful force, and that means that it's going to interact
almost all the time, and so you get lots of
particles contributing. But if you're like going to measure it
per particle, I think I think it's just another way
of saying the same thing. I think. Um, you know,
the strength of the force between them is another way
of saying how likely are they to interact or not

(15:09):
the other Fascinating about the weak force. One another reason
to think about why it's weak is that it doesn't
interact over a very long range, like electromagnetism to electrons
that are like a thousand miles away from each other,
they can feel each other and they feel each other's
electric fields. Right that electromagnetism extends infinitely far the weak force.

(15:29):
Another way to think about why it's weak is that
it only interacts with things very very near it, right,
Like you have to be really close to the neutrino
to interact with it. Is that true? Like to electrons,
even though even if there are millions of light years apart,
they'll still feel each other. Absolutely, You feel the electric
field from electrons in Alpha Centauri or the Andromeda galaxy

(15:52):
or halfway across the universe. Absolutely? Is that why I
feel like I'm being pulled apart? No, that it's like
maybe the only scientific connection between astronomy and astrology, Like,
are you affected by the movements of the planets? Well, maybe,
but it's really negligible. And I also remember that it's

(16:12):
time delayed. You know, if you if there are electrons
and Alpha Centauri and somebody wiggles them, you don't see
those wiggles until until the information comes here, which takes
you know, which travels at the speed of light, so
it takes a long time. But you're saying the weak
Newark force doesn't have that long range, like at some
point two particles that feel it don't affect each other

(16:33):
with the weak force. That's right. The range of the
force is really tiny. It's like the diameter of a proton, right,
So these particles have to be really close together. It's
just another way of thinking about whether these two things
will interact. I think about it's sort of like, you know,
imagine you're throwing two baseballs at each other, right, They're
less likely to interact than if you're throwing two basketballs

(16:53):
at each other, or two um or some really enormous ball,
some like enormous yoga bouncy yoga ball at each other, right,
And so the side this is what we call cross
section in physics, because the cross section of those balls
tells you how likely they are to hit each other.
Balls with a really small cross section, like if you're throwing,
you know, pebbles at each other, it's much harder for

(17:14):
them to hit. And so the range of this force
tells you basically the cross section of their interaction. And
so the weak force is a really small range, which
makes it less likely to interact. When they interact that
you know, they still bounce off each other, like anything else,
just less likely to happen. So what happens when you
get further away? Does the force just drops off? Or

(17:34):
you know, like I've heard that at some point the
weak force doesn't travel far because the particles decay or
they don't last far far out enough. Yeah, that's a
really fascinating way to think about it. Um. Yeah, the
weak force, it just is negligible beyond a certain distance,
like you know, it's basically zero. And another way to
answer the question why is the weak force weak? I

(17:55):
mean one way to say, as well, it just has
a number associated with it, and that number is smaller
than the number associated with electromagnetism or you know, the
strong force, And then of course you can ask why.
But one way to explain that is to think about
it in terms of the particles that transmit these forces. Right,
we think about like the photon. The photon is the
thing that transmits electromagnetism. Right, what do we mean by that, Well,

(18:18):
we have this sort of picture that like two electrons
coming near each other, one of them can shoot off
a photon to hit the other electron and push it away,
And that's like how electrons repel via a photon, and
we we use that same sort of picture for all
the forces. Actually, but the particles that are associated with
the weak force, they are not massless like the photon.

(18:39):
Is the reason electromagnetism extends so far is because the
photon is massless. It zooms away the speed of light
and it doesn't decay. Right, Photons can go forever, But
the weak force has these really heavy particles. They're really
really heavy, and so they don't go very far before
they basically decays. Like if I was trying to hit
you with a bowling ball and my range would be limited. Yeah,

(19:03):
Or if you, like you know, had taped a bunch
of stuff together very loosely and then try to throw
it at me and it exploded in mid air before
it got to me, like throwing the sandball. At some
point it might break up a standball exactly. It's like
throwing a sandball. You know, you're not really getting get
hit by the full force of the sandball unless you're
really close. And that's that's fascinating. Like these particles, these

(19:25):
particles that mediate the weak force bosons, why are they
so heavy and the and the photon is masseless. That's
like one of the deep questions in physics over the
last few decades. And that's why the photon can go
to infinity because it's massless and it just keeps going
right exactly. That's why electromagnetism is powerful, and that's why
it's range is infinite, and the weak force is very

(19:47):
weak because the things that carry it are very fat
and slow. You know. It's like, you know, if you
wanted to send letters ups drivers are super super faster
driving Lamborghinis, right, and uh, instead you sent it via
I don't know, um u s mail and they're driving,
you know, a big, heavy slow bus or something. Um
your letters is not going to get there is fast

(20:07):
or might not even get there. So the thing that
carries the messages, the information of the weak force, is
big and heavy weeks and that that's what makes the
blame the messenger. And the fascinating thing is that that's
really only relevant um sort of late in the universe.
That's relevant when everyone there isn't a whole lot of energy,

(20:29):
because the mass these particles makes a difference when everything
doesn't have a lot of energy. But if everything was
really hot and dense and and zooming around, then it
wouldn't really matter what the mass of these particles was, right,
they have a little bit of mass or not they
had a lot of energy, wouldn't make any difference. And
that's why we think back from the beginning of the universe,
electromagnetism and the weak force had the same strength because

(20:53):
everything we're just closer together and interacting the same way. Yeah,
and those particles, the ones that carry the weak force,
just had enough energy to get further. The fact that
they had mass didn't really matter because they had so
much energy it was negligible. All right, So that's the
weak force. Now we know it's a force, and we
know why it's weak, and so let's get into what's
interesting about the weak force? Why is it weak? Um?

(21:15):
What's weird about it? Why do we have it? And
how did it help us discover the Higgs Boson? But
first let's take a quick break. All right, Hey, Daniel,
do you think the weak force knows that it's called

(21:37):
the weak force? You know what? I think its agents
have been working for quite a while to get a
name change. Yeah, I think it needs a pr overhaul
for sure. Should be called Would you like to be
called doctor Week or Daniel weak or I don't think
anyone Master of the Week Fource experts still worked out
for John Week that franchise exactly force then exactly Well,

(22:05):
you know, what would you have called the weak force? Well,
I don't know anything about it. Much about it. You
should listen to this podcast to explain it to you.
It's really good. Well, all I know is that it's
weak and that it's a force. But you know, is
there what do we know about it that might give
it some identity? Like what's special about? What are you
special about it? It's pretty weird. It can do some
things that other forces can't do. It's sort of like

(22:28):
messes with your mind. A lot of the things that
we thought we knew about the universe, that we just
assumed were fundamentally true about the universe, the weak force
just sort of breaks those rules and shrugs and moves on.
And so it's a great window into like what is
the sort of the limitation? What can forces do in
the universe. It turns out they can do a lot
of things that we thought were impossible. And that's what
the weak force can do. Yeah, that's what the weak

(22:48):
force can do. For example, the weak force can change
cork flavors. We had a whole podcast episode about cork flavors.
And for those of you are thinking, what what's the
cork and how does it have flavors? We're not talking
about European yogurt snacks. There are flavors snacks called cork.
We're talking about fundamental particles. Yeah, and so this the
weak force can change the flavor of a cork, yeah, exactly.

(23:12):
Electromagnetism can't do that, right, you have you have a
charm cork. It can't give off a photon and then
become an up cork. That doesn't happen, right, But if
the charm interacts using the weak force, you can give
off one of the particles that it transmits, and if
it can become for example, a down cork or a
strange cork can become an up cork, right, or top

(23:32):
cork can become a bottom cork or a down cork, right,
And so it can actually change these flavors, and other
other forces are not allowed to do that well. And
that's kind of a big deal because if I change
all the flavors in the courts inside of your atoms,
you'd be in trouble. Right, Well, I think I'd be
even tasting charming and strange, but uh or more charming

(23:55):
and more strangers. Yeah, well, you know this. You think
of its sort of like a ladder. There's the lowest
energy ones, the lowest mass ones. Those are the upcork
and the down cork, and if you have the heavier corks,
then that they tend to decay down the ladder. Things
in the universe tend to be the lowest energy state,
the lowest mass particles. So if you have the heavier
particles like the top, then it uses the weak force

(24:17):
to sort of step down that ladder, down to the
up and the down and I and you and banana
you've ever eaten are made up of just upcorks and
down corks and of course electronics. But it also changes.
It can change the upquorks and down corks back into
each other. And that's actually what we call radioactive beta decay.
That's how you change, for example, a neutron into a

(24:37):
proton is by changing is by going back and forth
between upquorks and down corks, because that's the difference between
neutrons and protons. It's just one up versus one down.
So it's weird because it can really mess with the
identity of matter. Right Like, if if all my quorks
change identities, I would probably blow up, right, I wouldn't
be able to stay together, right Like, if all my

(24:57):
protons turned into neutrons, you know, goodbye hore. Yeah, well,
protons don't turn into neutrons, right. Protons are stable, which
is a whole other fascinating thing, like can protons live
for the whole life of the universe or do they
eventually decay? Currently we think that protons live for like
zillions of years, but neutrons don't. Neutrons will eventually turn
into protons, and that's fascinating. And that's what the that's

(25:18):
what the weak nuclear force does, and only the weak
force can do that. Okay, that's weird. Um, so maybe
I would call it a weird force. I don't know.
The flavor force A force seems a little the tasty force.
You know. The particles that it uses are also weird.
Like we said, the electromagnetism has the photon, right, and

(25:41):
that's how it transmits information. And the weak force is
more complicated. It has three particles that transmit its forces.
Has this particle we call the z boson and then
it has the W plus and the W minus and
we call them plus and minus because those particles themselves
have electric charge. So it's the particles of one force

(26:02):
feel the forces of another force. So affect the weak
force using a magnet is kind of what you're saying, yeah, exactly.
Or the particles that transmit the weak force can shoot
off photons, right, they interact with each other using electromagnetism. Yeah,
and that was a big clue. We'll talk about that later,

(26:22):
that there's a deep, deep connection between the weak force
and electromagnetism. It's kind of like it would be cool,
like if, for example, you can affect gravity using electromagnetism, right,
Like that would be crazy. Then you can yeah, right exactly,
you could like make a magnet which turned off gravity
or so that would be cool. And you know, we
hope one day in the far future to have a

(26:43):
unified understanding of all the forces, take gravity, turn into
a quantum mechanical theory, which we haven't done yet and
have no clue how to do, and then somehow unify
it with the other forces and show that show that
there's they're all just part of the same larger force.
In that case, then maybe you could do what you
just said is use one part of the force to
balance another part of the force and affected. So yeah,
I think you just invented an anti gravity machine right here, right,

(27:07):
A should kick one what one half of a Nobel
prize then, or let's go with were equal. That's probably
the chances that I will get one. Um, I think
that's probably accurate. Yeah, alright, so well let's get into
Now we know what it is, we know what it's

(27:29):
kind of weird. Wait, but wait, there's more. There's even
a weirder thing about that. I thought it was weak,
but there's more. All right, it's weak, but it's got
a long backstory. Right. It's one of these superhero characters
with like a really deep interesting connection. It was affected
in its childhood and it's carrying all that back. Black
Widow's not a lot of superpowers, but you're like, what
is going on with her? Oh? You mean Black Wood

(27:52):
of the superhero not the actual Spider. Yeah exactly. She
she looks good in leather and she can really kick. Yeah,
but she has all the this mysterious Russian spy backstory.
Yeah exactly. She's intimidating. Now the one of the weirdest things.
But the weak force is that it breaks what we
thought was a fundamental symmetry in the universe, and that

(28:13):
is that we we think that it shouldn't make a
difference sort of how you draw your X, Y and
Z axes. Like, if you have to draw, you draw
an X axis and Y axis, you put them in
ninety degrees with each other. Right, then you're gonna draw
Z access you want to put it in ninety degrees.
But then there's a question do you draw it like
sort of up above the X Y axis or down
below right? And the difference is what we call handedness.

(28:36):
Is it a left handed system or a right handed system.
It's really just arbitrary, and so because most of us
are right handed, we tend to draw those things the
way you would have the first three fingers on your
right hand point, so we call them right handed coordinates.
It's kind of related to mirrors, right like you think
that physics should work the same on one side of
the mirror or in the reflection of the mirror exactly,

(28:56):
because if you take a right handed coordinate system and
you look in the mirror, then it looks left handed,
and so for a long time people thought, well, that's
just a thing we made up. It's just like human
it's not fundamental or physical, right, And so they said, well,
physics shouldn't matter. They should the physics shouldn't depend on
whether things are right handed or left handed. So they
made this assumption. They said, well, we assume that any

(29:17):
experiment you do, if you watch the experiment in the mirror,
you should also be able to do that mirror experiment, right,
that the laws of physics should work the same here
as they do in in the mirror. Right, So, like
you do some experiment you watch in the mirror, you
should you should be able to do that same experiment,
or our laws of physics should still govern what's happening
in the mirror. But you're saying the week four is

(29:39):
totally doesn't care. Yeah, And this is one of the
great stories of physics is that nobody checked for a
long long time, Like they checked the electromagnetism be up,
it's true. They checked the strong force e up, it's true.
And they thought, well, this is just so fundamental and obvious,
like we don't need to check it. You know. It's
like you know, do you check that the sun doesn't
like come out and middle of the night. No, you

(30:01):
just they don't get up in the middle of the
night and check if the sun is sneaking sneaking around, right?
You just you checked at at sunset, you check at
its sun at sunrise, and you assume what else is happening? Right?
So people thought, well, the weak force is really hard
to test, so we'll just assume that it also respects
the symmetry called parody. And then in the fifties some
theorists realized nobody has actually ever checked this, so maybe

(30:22):
somebody should. And this is a great story about a
physicist at Columbia. She was planning to go on vacation
with her husband for Christmas, and she said, you know what,
I can't go on vacation. I can't relax without knowing
the answer to this deep question. Sounds like a physicist exactly.
So her husband went on vacation by himself and she
stayed back and she did these experiments where she demonstrated.

(30:44):
She asked the question, would the weak force look the
same in the mirror? And she said, up, this really
complicated but but very clever experiment. And it's difficult to
describe with the audio, so I encourage everybody to check
out or hey, your video on on this experiment, which
you can find by googling at the short version together
Daniel don't remember we made it with the Derek Mueller

(31:05):
of veritassium. If you look up. Yeah, it's a great video.
It's a great video. It's called do particles respect time symmetry?
Or do particles go backwards in time? In that video
you can see that the weak force doesn't work the
same in the mirror. In fact, in the mirror it
works exactly the opposite. So not only does it not
like respect this basic symmetry we assume was a true
thing about the universe, it violates it almost. So it's weak,

(31:29):
but it's like the rebel force, yeah, which means that
like our universe is, you know, has a handedness. It's
not like it could have been this or it could
have been that. It is one way right. And anytime
you see a kind of thing like that in physics,
where it's like an arbitrary choice between two things you
expected to be balanced or even or symmetric, and then
it's not, that's a clue that tells you something happened

(31:51):
when the universe was being cooked up, that it went
this way and not that way. What is that? Yeah?
It makes you realize that the universe maybe it doesn't
have laws, or the laws you thought real to universe
are not always true exactly. It makes you wonder is
there a deeper understanding in which it had to be
this way? Right? Is it just arbitrary and random and
we live in a multiverse and it's one of a

(32:13):
bazillion and there's no reason for it. I don't like
that idea. I think it's a clue that there's something
deeper going on. There's another way to think about the
way the universe works that requires it to be this
this thing that's weird to us. And and those are
the moments of insight. That's when when your intuition is
confronted by reality and you realize, here's a clue that
reality is quite different from my intuition. Those are learning moments, right, No, definitely,

(32:36):
I have a lot more respect now for the week
for us. I mean, it's so weird and breaks all
these laws. I feel like you just upgraded it from
Ringo to George Harrison, you know what I mean? Like
there you go. So, now we should be called the
well respected, well respected will light interesting, you should speak
with a stuffy British accent. Well, let's get into now

(32:59):
whether we even need the weak force or why is
it important? But first let's take a quick break. All right,
let's get into why we need the weak fource? Do

(33:21):
we even need it? Like, well, there's two questions, I
think practically, So practically, first of all, what would happen
if we didn't have the weak fource? We still be here?
And the second why is it important to physics? Yeah,
so that's a fun hypothetical question, like if you deleted
a law of physics, what would happen? Right? Well, obviously
everything would be different. Um you know, yeah, well you

(33:43):
wouldn't have radioactive decay, right For example, you wouldn't have
beta decay. The weak force is important to making things
happen in the center of suns and the structure of
the atom is partially controlled by the weak force, and
so everything would be different if we took it out.
If we eliminated Ringo Star from the Beatles, what would
happen to my atoms? Like would I just dissolve? Would
I explode? Would I feel just a little heavier or

(34:05):
what would happen, Well, it depends. Are you talking about
starting from the beginning of the universe never having the
weak force, or having the current universe and then just
turning it off. Let's do the second one first, So
clip the switch, the weak force just quit goes away.
What happens the first caveat is it's impossible. It doesn't
make any sense for reasons we'll talk about in a minute.
Because it turns out the weak force is just entangled

(34:27):
with everything else and you can't get rid of it
right the way. You can't just fire your drummer, um,
and the universe wouldn't make any sense if you did that.
But say you just turn that off somehow, somehow you're
able to get to the control penalty universe and turn
off the weak force. What would happen. I don't think
you would feel it immediately? Um. I think we would
never interact with new trinos again. Right, New trinos would

(34:49):
just become invisible, becoming decoupled with them. But yeah, no
big laws whenever they feeling. New trinos would be harder
to run nuclear reactors right, and fission wouldn't work the
same way, So we'd have to re engineer all of that.
But again, you know, um, not everybody is a big
fan of nuclear power. The structure the atom would be
a little bit different, right, I mean, it certainly plays
a role in how the nucleus is held together and

(35:11):
how it gets broken up. So that's a good deep question.
I'm not sure the answer of how it changes structure
the atom, but mostly I think you could just totally
ignore the neutrinos that were already mostly ignoring all right, So, um,
so then what's the other answer that if we started
off the universe without the weak force, would we end
up in the same spot. Yeah, that's a great question.

(35:32):
I think I have to deflect that question because I
don't think the universe makes any sense without the weak force.
And the reason is that it turns out the weak
force is not its own thing. It's not like a
completely separate thing that we're like right now, we don't
understand any connection between gravity and electromagnetism. They seem like
totally different phenomena with no relationship. Turns out the weak

(35:53):
force is not its own thing. It's actually part of electromagnetism,
or said more correctly, the weak force and ectro magnetism
are part of one larger force. I've heard that before,
that the weak force and the electromagnetic force are actually
just one. What does that mean, Like they're they're actually
the same particles, but they behave differently or they're all

(36:13):
like different flavors of the same particles. What does that mean?
It means that they're all different parts of the same thing.
They're they're all like different sides of the same coin.
And I think a more intuitive analogy to help you
get there is to think about electricity and magnetism. Like
and fifty years ago, people thought electricity, Oh, that's the
thing that zaps you. Magnetism that's the thing that lets

(36:33):
magnets fly or magnets work, right, And I thought they
were totally separate. And it wasn't until Maxwell wrote down
Maxwell's equations and he realized, Hold on a second, the
laws that government electricity and the laws that governed magnetism
are basically the same thing when you write them down mathematically.
And you know, magnets can create currents and currents can

(36:54):
create magnets. So it turns out that there's just one force, electromagnetism.
And we had artificially set operated into two. We were
just categorizing the different parts of it separately and had
recognized that it makes much more sense when they're connected.
So we said, okay, let's just call this one force electromagnetism. Right,
So it's like the same force. It just sometimes acts

(37:15):
to create currents inside of wires and sometimes it acts
to repel magnets apart, but it's the same thing. You're
just one guy. Sometimes you're happy, sometimes you're grumpy, right, Like,
are you a different person when you're grumpy? I mean,
some people might say so, but I know deep down
you're you're really the same person. And so it makes
much more sense to say, oh, this is different sides
of somebody's personality. This is two different aspects of the

(37:38):
same thing sometimes like different feelings of it or different
behaviors of it. Yeah, exactly. And what we've discovered is
that the photon and the w and the z bosons
are all just parts of one force that we called
the electroweak force. And you notice what happened there is
that we merged electricity and magnetism into electromagnetism than we

(38:00):
added the weak force, and like magnetism just kind of
got squeezed out. It should have been called like electromagnetic
weak force or something like your weak magnetic force or
magneto weak force, right, electricity, electromagnetic That's how I would
have maybe count it. But so you're saying then that
electrons and W, the W and the z bosons, they're

(38:21):
all those are different, but they're all carriers of the
same force. Yeah, there's one larger, more complex force, and
we call it electroweak. And it has four carriers, the photon,
the two ws, and the z and has four carriers
to it. Does the weak force have like charge, you
know how we talked about electromagnetism has charge, and the

(38:41):
strong force has color color, and and the weak force
has its own thing. It's called weak hypercharge, which is
like a contradictory branding a great name, I know, super awesome,
not that awesome charge, it's kind of confusing. Has weak hypercharge.

(39:02):
And then together the combined electroweak force has something called
weak isospin, which is not has nothing to do with spin.
So it's a big mess, and it comes from a
historical naming accident. Really, the main lesson is just that
they can be described by sort of the same what
is it terms and the equations of the universe kind
of yeah, exactly, they have. The mathematics is very similar,

(39:24):
and in fact um when people were looking at that,
they noticed, like, these things are so similar, But why
is the photon have no mass and these other particles
have a lot of mass? Right, Like, that's why electricity
and magnetisms seem so different from the rest of the force,
because this one particle, the photon, has no mass, but
the other ones have a lot of mass. So that

(39:45):
was a big puzzle like fifty years ago, and that's
the puzzle that inspired Higgs himself to think up the
Higgs boson. Said well, maybe there's this other particle out there,
this other field, and it's interacting with these bosons and
it's giving them mass. He came up with a really
clever mathematical way to make that happen, to give mass
to just these particles and not to the photon. So

(40:06):
I think the conclusion of all it is then, is
that the weak force. It's there. It's kind of like
the conjoint twin of electromagnetism, right, it's not its own thing,
that's right, Yeah, exactly, And it's not very consequential in
the universe, meaning that you can take it away, but
we wouldn't instantly feel it. But it's sort of necessary, right,

(40:27):
It's part of the universe, and in fact, it kind
of gave us a lot of clues about the universe,
including the Higgs boson. That's right, and you can sort
of blame it on the Higgs, right. The Higgs is
the reason that the W and di z have so
much mass, and that's why it's so weak. So if
it wasn't for the Higgs holding it down, the weak
force would have had a much different career arc. Maybe
we should call it the I hate the Higgs force exactly.

(40:50):
Probably it's a mental state than the weak force. Yeah,
but it's like, you know, many Nobel prizes have been
won along the route to understanding this, Understanding that electricity
and magnetism are together with the weak force, understanding the
Higgs mechanism, all this stuff. These are a lot of
really important ideas, were all really complex. Mathematical machinery was

(41:13):
developed just to understand this, and it's really beautiful when
you learn that because it shows you how the structure
these theories really are deeply mathematical. Now, how much mathematics
really reveals the way the universe works. All right, something
on a note of beauty. That's pretty cool. Yeah, So
for those of you interested in learning more about it,
or encourage you to get a little bit into the

(41:35):
group theory because it connects for you the symmetry of
these things with the idea of particles carrying these forces
and why it has to be that way. It's really
deep and fascinating and we should dive into it on
another podcast episode. All right, Thanks for joining us. I
hope you enjoyed that. We'll see you next time. Thanks
for tuning in, and I hope it wasn't a weak episode.
I had a forceful impact on you. If you still

(42:03):
have a question after listening to all these explanations, please
drop us a line. We'd love to hear from you.
You can find us at Facebook, Twitter, and Instagram at
Daniel and Jorge that's one word, or email us at
Feedback at Daniel and Jorge dot com. Thanks for listening,
and remember that Daniel and Jorge Explain the Universe is
a production of I Heart Radio from more podcast from

(42:25):
my Heart Radio visit the I Heart Radio app, Apple Podcasts,
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Daniel Whiteson

Jorge Cham

Jorge Cham

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