The following is a conversation with Harry Cliff, a particle physicist at the University of Cambridge
working on the Large Hedron Collider Beauty Experiment that specializes in investigating
the slight differences between matter and antimatter by studying a type of particle called
the beauty quirk or B quirk. In this way, he's part of the group of physicists who are searching
for the evidence of new particles that can answer some of the biggest questions in modern physics.
He's also an exceptional communicator of science with some of the clearest and most captivating
explanations of basic concepts in particle physicists that I've ever heard. So when I visited London,
I knew I had to talk to him. And we did this conversation at the Royal Institute Lecture
Theatre, which has hosted lectures for over two centuries from some of the greatest scientists
and science communicators in history, from Michael Faraday to Carl Sagan. This conversation was
recorded before the outbreak of the pandemic. For everyone feeling the medical and psychological
and financial burden of this crisis, I'm sending love your way. Stay strong, we're in this together,
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to support this podcast. And now here's my conversation with Harry Cliff. Let's start with
probably one of the coolest things that human beings have ever created the large hand on collider
OHC. What is it? How does it work? Okay, so it's essentially this gigantic 27 kilometer
circumference particle accelerator. It's this big ring. It's buried about 100 meters underneath
the surface in the countryside, just outside Geneva in Switzerland. And really what it's for
ultimately is to try to understand what are the basic building blocks of the universe. So you
can think of it in a way as like a gigantic microscope and the analogy is actually fairly
precise. So gigantic microscope. Effectively, except it's a microscope that looks at the structure
of the vacuum. In order for this kind of thing to study particles, which are microscopic entities,
it has to be huge. Yes. It's a gigantic microscope. So what do you mean by studying vacuum?
Okay, so I mean, so particle physics as a field is kind of badly named in a way because
particles are not the fundamental ingredients of the universe. They're not fundamental at all. So
the things that we believe are the real building blocks of the universe are objects, invisible,
fluid like objects called quantum fields. So these are fields like like the magnetic field
around a magnet that exists everywhere in space. They're always there. In fact, actually, it's
funny that we're in the Royal Institution because this is where the idea of the field was effectively
invented by Michael Faraday doing experiments with magnets and coils of wire. So he noticed that,
you know, it's a very famous experiment that he did where he got a magnet on top of it,
a piece of paper, and then sprinkled iron filings. And he found the iron filings arranged themselves
into these kind of loops, which was actually mapping out the invisible influence of this
magnetic field, which is a thing, you know, we've all experienced, we've all felt held a magnet
and or two poles of magnet and pushed them together and felt this thing, this force pushing back. So
these are real physical objects. And the way we think of particles in modern physics is that
they are essentially little vibrations, little ripples in these otherwise invisible fields that
are everywhere, they fill the whole universe. You know, I don't apologize, perhaps for the
ridiculous question. Are you comfortable with the idea of the fundamental nature of our reality
being fields? Because to me, particles, you know, a bunch of different building blocks makes more
sense sort of intellectually, sort of visually, like it's, it seems to, I seem to be able to
visualize that kind of idea easier. Are you comfortable psychologically with the idea that
the basic building block is not a block, but a field? I think it's, I think it's quite a magical
idea. I find it quite appealing. And it's, well, it comes from a misunderstanding of what particles
are. So like when you, when we do science at school, and we draw a picture of an atom, you draw,
like, you know, nucleus with some protons and neutrons, these little spheres in the middle,
and then you have some electrons that are like little flies flying around the atom. And that is
a completely misleading picture of what an atom is like. It's nothing like that. The electron is
not like a little planet orbiting the atom. It's this spread out, wibbly, wobbly, wave-like thing.
And we know we've known that since, you know, the early 20th century, thanks to quantum mechanics.
So when we carry on using this word particle, because sometimes when we do experiments,
particles do behave like they're little marbles or little bullets, you know. So in the LHC,
when we collide particles together, you'll get, you know, you'll get like hundreds of particles
or flying out through the detector. And they all take a trajectory and you can see from the detector
where they've gone and they look like they're little bullets. So they behave that way, you know,
a lot of the time. But when you really study them carefully, you'll see that they are not little
spheres. They are these ethereal disturbances in these underlying fields. So this is really
how we think nature is, which is surprising, but also I think kind of magic. So, you know, we are,
our bodies are basically made up of like little knots of energy in these invisible objects that
are all around us. And what, what is the story of the vacuum when it comes to LHC? So why did
you mention the word vacuum? Okay, so if we just, if we go back to like the physics, we do know.
So atoms are made of electrons, which were discovered 100 or so years ago. And then in the
nucleus of the atom, you have two other types of particles. There's an up, something called an up
quark and a down quark. And those three particles make up every atom in the universe. So we think
of these as ripples in fields. So there is something called the electron field. And every
electron in the universe is a ripple moving about in this electron field. So the electron field is
all around us. We can't see it, but every electron in our body is a little ripple in this thing that's
there all the time. And the quark field is the same. So there's an up quark field and an up quark
is a little ripple in the up quark field. And the down quark is a little ripple in something else
called the down quark field. So these fields are always there. Now, there are potentially, we,
we know about a certain number of fields in what we call the standard model of particle physics.
And the most recent one we discovered was the Higgs field. And the way we discovered the Higgs
field was to make a little ripple in it. So what the LHC did, it fired two protons into each other
very, very hard with enough energy that you could create a disturbance in this Higgs field. And that's
what shows up as what we call the Higgs boson. So this particle that everyone was going on about
eight or so years ago is proof really, the particle in itself is, I mean, it's interesting,
but the thing that's really interesting is the field, because it's the Higgs field that we believe
is the reason that electrons and quarks have mass. And it's that invisible field that's always there
that gives mass to the particles. The Higgs boson is just our way of checking it's there,
basically. So the large electron collider, in order to get that ripple in the Higgs field,
it requires a huge amount of energy, so that's why you need this huge, that's why size matters here.
So maybe there's a million questions here, but let's backtrack. Why does size
matter in the context of a particle collider? So why does bigger allow you for higher energy
collisions? Right. So the reason, well, it's kind of simple really, which is that there are two types
of particle accelerator that you can build. One is circular, which is like the LHC, the other is
a great long line. So the advantage of a circular machine is that you can send particles around
a ring and you can give them a kick every time they go around. So imagine you have a,
there's actually a bit of the LHC that's about only 30 meters long, where you have a bunch of
metal boxes, which have oscillating two million volt electric fields inside them, which are timed
so that when a proton goes through one of these boxes, the field it sees as it approaches is
attractive. And then as it leaves the box, it flips and comes repulsive and the proton gets
attractive and kicked out the other side. So it gets a bit faster. So you send it, and then you
send it back around again. And it's incredible. Like the timing of that, the synchronization,
wait, really? Yeah, yeah, yeah. That's, I think there's going to be a multiplicative effect on
the questions I have. Okay, let me just take that attention for a second. The orchestration of that,
is that fundamentally a hardware problem or a software problem? Like what, how do you get that?
I mean, I should first of all say, I'm not an engineer. So the guys, I did not build the LHC.
So they're people much, much better at this stuff than I could. For sure. But maybe,
but from your sort of intuition, from the, the echoes of what you understand,
what you heard of, how it's designed, what's your sense, what's the engineering aspects of it?
The acceleration bit is not challenging. Okay, I mean, okay, there is always challenges of
everything. But basically, you have these, the beams that go around the LHC, the beams of particles
are divided into little bunches. So they're called, they're a bit like swarms of bees, if you like.
And there are around, I think it's something of the order, 2000 bunches spaced around the ring.
And they, if you're a given point on the ring, counting bunches, you get 40 million bunches
passing you every second. So they come in, like, you know, like cars going past on a very fast
motorway. So you need to have, if you're an electric field that you're using to accelerate the
particles, that needs to be timed so that as a bunch of protons arrives, it's got the right
sign to attract them and then flips at the right moment. But I think the voltage in those boxes
oscillates at hundreds of megahertz. So the beams are like 40 megahertz, but it's oscillating much
more quickly than the beam. So I think, you know, it's difficult engineering, but in principle,
it's not, you know, a really serious challenge. The bigger problem.
This probably engineers like screaming at you right now.
Probably. Okay. So in terms of coming back to this thing, why is it so big? Well, the reason is
you want to get the particles through that accelerating element over and over again.
So you want to bring them back round. That's why it's round. The question is, why couldn't you
make it smaller? Well, the basic answer is that these particles are going unbelievably quickly.
So they travel at 99.9999991% of the speed of light in the LHC. And if you think about,
say, driving your car around a corner at high speed, if you go fast, you need a very,
you need a lot of friction in the tires to make sure you don't slide off the road.
So the, the limiting factor is how powerful a magnet can you make? Because it's what we do
is magnets are used to bend the particles around the ring. And essentially the LHC,
when it was designed, was designed with the most powerful magnets that could conceivably be built
at the time. And so that's your kind of limiting factor. So if you wanted to make the machines
smaller, that means a tighter bend, you need to have a more powerful magnet. So it's this toss
up between how strong your magnets versus how big a tunnel can you afford, the bigger the tunnel,
the weaker the magnets can be, the smaller the tunnel, the stronger they've got to be.
Okay. So maybe can we backtrack to the standard model and say what kind of particles there are
period. And maybe the history of kind of assembling that the standard model of physics and then
how that leads up to the hopes and dreams and the accomplishments of the large hydrocolider.
Yeah, sure. Okay. So all of 20th century physics in like five minutes.
Yeah, please.
Okay. So, okay, the story really begins properly. End of the 19th century, the basic view of matter
is that matter is made of atoms and that atoms are indestructible, immutable little spheres
like the things we were talking about that don't really exist. And there's one atom for every
chemical element. So there's an atom for hydrogen, for helium, for carbon, for iron, etc. And they're
all different. Then in 1897, experiments done at the Cavendish Laboratory in Cambridge, which is
where I'm still where I'm based, showed that there are actually smaller particles inside the atom,
which eventually became known as electrons. So these are these negatively charged things that
go around the outside. A few years later, Ernest Rutherford, very famous nuclear physicist,
one of the pioneers of nuclear physics, shows that the atom has a tiny nugget in the center,
which we call the nucleus, which is a positively charged object. So then by 1910,
11, we have this model of the atom that we learn in school, which is you've got a nucleus,
electrons go around it. Fast forward, you know, a few years, the nucleus, people start doing
experiments with radioactivity where they use alpha particles that are spat out of radioactive
elements as bullets, and they fire them at other atoms. And by banging things into each other,
they see that they can knock bits out of the nucleus. So these things come out called protons,
first of all, which are positively charged particles about 2000 times heavier than the
electron. And then 10 years later, more or less, a neutral particle is discovered called the neutron.
So those are the three basic building blocks of atoms. You have protons and neutrons in the
nucleus that are stuck together by something called the strong force, the strong nuclear force.
You have electrons in orbit around that, held in by the electromagnetic force, which is one of the
forces of nature. That's sort of where we get to by like 1932, more or less. Then what happens is
physics is nice and neat. In 1932, everything looks great, got three particles and all the
atoms are made of that's fine. But then cloud chamber experiments, these are devices that can
be used to the first devices capable of imaging subatomic particles. So you can see their tracks
and they're used to study cosmic rays, particles that come from outer space and bang into the
atmosphere. And in these experiments, people start to see a whole load of new particles.
So they discover for one thing, antimatter, which is the sort of a mirror image of the particles.
So we discover that there's also, as well as a negatively charged electron, there's something
called a positron, which is a positively charged version of the electron. And there's an antiproton,
which is negatively charged. And then a whole load of other weird particles start to get discovered.
And no one really knows what they are. This is known as the zoo of particles.
Are these discoveries not the first theoretical discoveries? Or are they discoveries in experiment?
So like, well, yeah, what's the process of discovery for these early sets of?
It's a mixture. I mean, the early stuff around the atom is really experimentally driven. It's not
based on some theory. It's exploration in the lab using equipment. So it's really people just
figuring out, getting hands on with the phenomena, figuring out what these things are. And the theory
comes a bit later. That's not always the case. So in the discovery of the antielectron, the positron,
that was predicted from quantum mechanics and relativity by a very clever theoretical
physicist called Paul Dirac, who was probably the second brightest physicist of the 20th century,
apart from Einstein, but isn't anywhere near as well known. So he predicted the existence of the
antielectron from basically a combination of the theories of quantum mechanics and relativity.
And it was discovered about a year after he made the prediction.
What happens when an electron meets a positron?
They annihilate each other. So when you bring a particle and this antiparticle together,
they react, well, they just wipe each other out and their mass is turned into energy,
usually in the form of photons. So you get light produced. So when you have that kind of situation,
why does the universe exist at all if there's matter and antimatter?
Oh, God, now we're getting into really big questions. So defensive, do you want to go there now?
Yeah, maybe let's go there later. That's because I mean, that is a very big question.
Yeah, let's take it slow with a standard model. So, okay, so there's matter and
anti-matter in the 30s. So what else? So matter and anti-matter and then a load of
new particles start turning up in these cosmic ray experiments, first of all.
And they don't seem to be particles that make up atoms. They're something else.
They all mostly interact with a strong nuclear force. So they're a bit like protons and neutrons.
And by in the 1960s, in America particularly, but also in Europe and Russia, scientists start
to build particle accelerators. So these are the forerunners of the LHC. So big ring-shaped
machines that were hundreds of meters long, which in those days was enormous. Most physics,
up until that point, had been done in labs in universities with small bits of kit.
So this is a big change. And when these accelerators are built, they start to find they can produce
even more of these particles. So I don't know the exact numbers, but by around 1960,
there are of order 100 of these things that have been discovered. And physicists are kind of
tearing their hair out because physics is all about simplification. And suddenly,
what was simple has become messy and complicated. And everyone sort of wants to understand what's
going on. There's a quick kind of a side and probably really dumb question. But how is it
possible to take something like a like a photon or electron and be able to control it enough,
like to be able to do a controlled experiment where you collide it against something else?
Is that that seems like an exceptionally difficult engineering challenge? Because you mentioned
vacuum too. So you basically want to remove every other distraction and really focus on this
collision. How difficult of an engineering challenge is that just to get a sense?
And it is very hard. I mean, in the early days, particularly when the first accelerators are
being built in like 1932, Ernest Lawrence builds the first, what we call a cyclotron,
which is like a little accelerator, this big or so. There's another one, that big,
this tiny little thing. Yeah. I mean, so most of the first accelerators were what we call fixed
target experiments. So you had a ring, you accelerate particles around the ring, and then
you fire them out the side into some target. So that makes the kind of the colliding bit is
relatively straightforward because you just fire it up, whatever it is you want to fire it at.
The hard bit is the steering the beams with the magnetic fields getting strong enough
electric fields to accelerate them, all that kind of stuff. The first colliders where you have two
beams colliding head on, that comes later. And I don't think it's done until maybe the 1980s.
I'm not entirely sure, but it's much harder problem.
That's crazy because you have to perfectly get them to hit each other. I mean, we're talking
about, I mean, what scale, the temporal thing is a giant mess, but the spatially, the size
is tiny. Well, to give you a sense of the LHC beams, the cross-sectional diameter is,
I think, around a dozen or so microns. So 10 millionths of a meter.
And a beam, sorry, just to clarify, a beam contains how many, is it the bunches that you
mentioned? Is it multiple parts or is it just one part?
Oh, no, no. The bunches contain, say, 100 billion protons each. So bunches, it's not really bunch
shaped. They're actually quite long. They're like 30 centimeters long, but thinner than a human hair.
So they're like very, very narrow, long sort of objects. So those are the things. So what happens
in the LHC is you steer the beams so that they cross in the middle of the detector. So they
basically have these swarms of protons that are flying through each other. And most of that,
you have 100 billion coming one way, 100 billion another way, maybe 10 of them will hit each other.
Oh, okay. So this, okay, that makes a lot more sense. So that's nice. So you're trying to use sort
of, it's like probabilistically, you're not, you can't make a single particle collide with
a single other. That's not an efficient way to do it. You'd be waiting a very long time to get
anything. Yeah. So you're basically right. You're relying on probability to me that some fraction
of them are going to collide. And then you know, which is it's a swarm of the same kind of particle.
So it doesn't matter which ones hit each other. Exactly. I mean, that that's not to say it's
not hard. You've got a, one of the challenges to make the collisions work is you have to squash
these beams to very, very, the basic, the narrower they are, the better, because the higher
chances of them colliding. If you think about two flocks of birds flying through each other,
the birds are all far apart in the flocks. There's not much chance that they'll collide if they're
all flying densely together, and they're much more likely to collide with each other. So
that's the sort of problem. And it's tuning those magnetic fields, getting them,
the magnetic fields powerful enough that you squash the beams and focus them so that you get
enough collisions. That's super cool. Do you know how much software is involved here? I mean,
it's sort of, I come from the software world and it's fascinating. This seems like it's a software
as buggy and messy. And so like you almost don't want to rely on software too much. Like if you
do, it has to be like low level, like for trans style programming. Do you know how much software is
in the large Hadron Collider? I mean, it depends on which level a lot. I mean, the whole thing is
obviously computer controlled. So I mean, I don't know a huge amount about how the software for the
actual accelerator works. But you know, I've been in the control center. So that's certain,
there's this big control room, which is like a bit like a NASA mission control with big banks of,
you know, desks where the engineers sit and they monitor the LHC, because you obviously can't be
in the tunnel when it's running. So everything's remote. I mean, one sort of anecdote about the
sort of software side in 2008, when the LHC first switched on, they had this big launch event,
and then, you know, big press conference party to inaugurate the machine. And about 10 days after
that, they were doing some tests. And the, this dramatic event happened where a huge explosion
basically took place in the tunnel that destroyed or damaged, badly damaged about about half a
kilometer of the machine. But the stories, the engineers are in the control room that day.
One guy told me this story about, you know, basically all these screens they have in the
control room started going red. So all these alarms like, you know, kind of in software going off,
and then they assume that there's something wrong with the software, because there's no way
something this catastrophic could have happened. But I mean, when I worked on, when I was a PhD
student, one of my jobs was to help to maintain the software that's used to control the detector
that we work on. And that was, it's relatively robust, not so you don't want it to be too fancy,
you don't want it to sort of fall over too easily. The more clever stuff comes when you're talking
about analyzing the data. And that's where the sort of, you know, are we jumping around too much?
Do we finish with a standard model? We didn't know. We didn't. So we even started talking
about quarks. We haven't talked about them yet. No, we got to the messy zoo of particles.
Let me, let's go back there if it's okay. Okay, that's fine. Can you take us to the rest of the
history of physics in the 20th century? Okay, sure. Okay, so circa 1960, you have this,
you have these 100 or so particles, it's a bit like the periodic table all over again. So you've
got like, like having 100 elements, sort of a bit like that. And people try to start to try to impose
some order. So Murray Gelman, he's a theoretical physicist American from New York, he realizes
that there are these symmetries in these particles that if you arrange them in certain ways, they
relate to each other. And he uses these symmetry principles to predict the existence of particles
that haven't been discovered, which are then discovered in accelerators. So this starts to
suggest there's not just random collections of crap, there's like, you know, actually some
order to this underlying it. A little bit later in 1960, again, it's around the 1960s,
he proposes along with another physicist called George Zweig, that these symmetries arise because
just like the patterns in the periodic table arise, because atoms are made of electrons and
protons, that these patterns are due to the fact that these particles are made of smaller things.
And they are called quarks. So these are the particles they're predicted from theory.
For a long time, no one really believes they're real. A lot of people think that they're a kind of
theoretical convenience that happened to fit the data, but there's no evidence, no one's ever seen
a quark in any experiment. And lots of experiments are done to try to find quarks, to try to knock
a quark out of her. So the idea if protons are neutrons, they're made of quarks, you should be
able to knock a quark out and see the quark. That never happens. And we still have never actually
managed to do that. Really? No. So the way that it's done in the end is this machine that's built
in California at the Stanford lab, Stanford Linear Accelerator, which is essentially a gigantic
three kilometer long electron gun, fires electrons almost the speed of light at protons. And when
you do these experiments, what you find is a very high energy, the electrons bounce off small,
hard objects inside the proton. So it's a bit like taking an x-ray of the proton, you're firing
these very light high energy particles, and they're pinging off little things inside the proton that
are like ball bearings, if you like. So you actually, that way, they resolve that there are
three things inside the proton, which are quarks, the quarks that Gellman and Zweig had predicted.
So that's really the evidence that convinces people that these things are real. The fact that
we've never seen one in an experiment directly, they're always stuck inside other particles.
And the reason for that is essentially to do with a strong force, the strong force is the force
holds quarks together. And it's so strong, it's impossible to actually liberate a quark. So if
you try and pull a quark out of a proton, what actually ends up happening is that the, you kind
of create this, that this spring like bond in the strong force, you imagine two quarks that are held
together by a very powerful spring, you pull and pull and pull, more and more energy gets stored in
that bond, like stretching a spring. And eventually the tension gets so great, the spring snaps,
and the energy in that bond gets turned into two new quarks that go on the broken ends. So you
started with two quarks, you end up with four quarks. So you never actually get to take a quark
out, you just end up making loads more quarks in the process. So how do we, again, forgive the dumb
question, how do we know quarks are real then? Well, A, from these experiments where we can
scatter, you fire electrons into the protons, they can borrow into the proton and knock off,
and they can bounce off these quarks. So you can see from the angles the electrons come out.
I see, you can infer. You can infer that these things are there. The quark model can also be
used, it has a lot of success, you can use it to predict the existence of new particles that
hadn't been seen. So, and it basically, there's lots of data basically showing from, you know,
when we fire protons at each other at the LHC, a lot of quarks get knocked all over the place.
And every time they try and escape from, say, one of their protons, they make a whole jet
of quarks that go flying off as bound up in other sorts of particles made of quarks. So
the all the sort of the theoretical predictions from the basic theory of the strong force and the
quarks all agrees with what we are seeing experiments. We've just never seen an actual quark on its own
because unfortunately it's impossible to get them out on their own. So quarks, these crazy,
smaller things, they're hard to imagine are real. So what else? What else is part of the story here?
So the other thing that's going on at the time around the 60s is an attempt to understand the
forces that make these particles interact with each other. So you have the electromagnetic force,
which is the force that was sort of discovered to some extent in this room or at least in this
building. So the first, what we call quantum field theory of the electromagnetic force is developed
in the 1940s and 50s by Feynman, Richard Feynman, amongst other people, Julian Schringer, Thomas
Naga, who come up with the first what we call a quantum field theory of the electromagnetic force.
And this is where this description of which I gave you at the beginning that particles are
ripples in fields. Well, in this theory, the photon, the particle of light is described as a ripple
in this quantum field called the electromagnetic field. And the attempt then is made to try,
well, can we come up with a quantum field theory of the other forces of the strong force and the
weak, the third force, which we haven't discussed, which is the weak force, which is a nuclear force.
We don't really experience it in our everyday lives, but it's responsible for radioactive decay.
It's the force that allows a radioactive atom to turn into a different element, for example.
And I don't know if we've explicitly mentioned, but so there's technically four forces. I guess
three of them will be in the standard model, like the weak, the strong, and the electromagnetic,
and then there's gravity. And there's gravity, which we don't worry about that because it's too
hard. Maybe we bring that up at the end. Gravity so far, we don't have a quantum theory of,
and if you can solve that problem, you'll win a Nobel Prize. Well, we're going to have to bring
up the graviton at some point. I'm going to ask you, but let's leave that to the side for now.
So those three, okay, Feynman, electromagnetic force, the quantum field, and where does the weak
force come in? Well, first of all, I mean, the strong force is a bit easier. So the strong
force is a little bit like the electromagnetic force. It's a force that binds things together.
So that's the force that holds quarks together inside the proton, for example. So a quantum
field theory of that force is discovered in the, I think it's in the 60s, and it predicts the existence
of new force particles called gluons. So gluons are a bit like the photon. The photon is the
particle of electromagnetism. Gluons are the particles of the strong force. And so there's,
just like there's an electromagnetic field, there's something called a gluon field,
which is also all around us. So some of these particles, I guess, are the force carriers or
whatever. They carry the... Well, it depends how you want to think about it. I mean, really,
the field, the strong force field, the gluon field is the thing that binds the quarks together.
The gluons are the little ripples in that field. So that like, in the same way that the photon is
a ripple in the electromagnetic field. But the thing that really does the binding is the field.
I mean, you may have heard people talk about things like, as you've heard the phrase, virtual
particle. So sometimes in some, if you hear people describing how forces are exchanged
between particles, they quite often talk about the idea that, you know, if you have an electron and
another electron, say, and they're repelling each other through the electromagnetic force,
you can think of that as if they're exchanging photons. So they're kind of firing photons
backwards and forwards between each other. And that causes them to repel.
That photon is then a virtual particle. Yes. That's what we call a virtual particle. In
other words, it's not a real thing. It doesn't actually exist. So it's an artifact of the way
theorists do calculations. So when they do calculations in quantum field theory, rather
than there's no one's discovered a way of just treating the whole field, you have to break
the field down into simpler things. So you can basically treat the field as if it's made up of
lots of these virtual photons. But there's no experiment that you can do that can detect these
particles being exchanged. What's really happening in reality is that the electromagnetic field
is warped by the charge of the electron, and that causes the force. But the way we do calculations
involves particles. So it's a bit confusing. But it's really a mathematical technique. It's not
something that corresponds to reality. I mean, that's part, I guess, of the Feynman diagrams.
Yes. Is this these virtual particles? Okay. That's right. Yeah. Some of these have mass,
some of them don't. What does that even mean not to have mass? And maybe you can say which one of
them has mass and which don't. And why is mass important or relevant in this field view of the
universe? Well, there are actually only two particles in the standard model that don't have mass,
which are the photon and the gluons. So they are massless particles. But the electron,
the quarks, and there are a bunch of other particles I haven't discussed. There's something
called a muon and a tau, which are basically heavy versions of the electron that are unstable. You
can make them in accelerators, but they don't form atoms or anything. They don't exist for long
enough. But all the matter particles, there are 12 of them, six quarks and six, what we call leptons,
which includes the electron and its two heavy versions and three neutrinos. All of them have
mass. And so do, this is the critical bit. So the weak force, which is the third of these
quantum forces, which is one of the hardest to understand, the force particles of that force
have very large masses. And there are three of them. They're called the W plus, the W minus,
and the Z boson. And they have masses of between 80 and 90 times that of the protons. They're
very heavy. Wow. They're very heavy things. What, the heaviest, I guess? They're not the heaviest.
The heaviest particle is the top quark, which has a mass of about 175-ish protons. So that's
really massive. And we don't know why it's so massive. But it's coming back to the weak force.
So the problem in the 60s and 70s was that the reason that the electromagnetic force is a force
that we can experience in our everyday lives. So if we have a magnet and a piece of metal,
you can hold it a meter apart if it's powerful enough and you'll feel a force. Whereas the weak
force only becomes apparent when you basically have two particles touching at the scale of
a nucleus. So we should get to very short distances before this force becomes manifest.
We don't get weak forces going on in this room. We don't notice them. And the reason for that is
that the particle, well, the field that transmits the weak force, the particle that's associated
with that field has a very large mass, which means that the field dies off very quickly.
So whereas an electric charge, if you were to look at the shape of the electromagnetic field,
it would fall off with this thing called the inverse square law, which is the idea that the
force halves every time you double the distance. No, sorry, it doesn't halve. It quarters every
time you double the distance between, say, the two particles. Whereas the weak force,
kind of, you move a little bit away from the nucleus and just disappears. The reason for
that is because these fields, the particles that go with them, have a very large mass.
But the problem that theorists faced in the 60s was that if you tried to introduce massive
force fields, the theory gave you nonsensical answers. So you'd end up with infinite results
for a lot of the calculations you tried to do. So it seemed that quantum field theory was incompatible
with having massive particles. Not just the force particles, actually, but even the electron was
a problem. So this is where the Higgs that we sort of alluded to comes in. And the solution was to
say, okay, well, actually, all the particles in the standard model are mass. They have no mass.
So the quarks, the electron, they don't have a mass. Neither do these weak particles. They
don't have mass either. What happens is they actually acquire mass through another process.
They get it from somewhere else. They don't actually have it intrinsically. So this idea that was
introduced by, well, Peter Higgs is the most famous, but actually there are about six people
that came up with the idea more or less at the same time, is that you introduce a new quantum
field, which is another one of these invisible things that's everywhere. And it's through the
interaction with this field that particles get mass. So you can think of, say, an electron
in the Higgs field. The Higgs field kind of bunches around the electron. It's sort of drawn
towards the electron. And that energy that's stored in that field around the electron is what we
see as the mass of the electron. But if you could somehow turn off the Higgs field,
then all the particles in nature would become massless and fly around at the speed of light.
So this idea of the Higgs field allowed other people, other theorists, to come up with a,
well, it was basically a unified theory of the electromagnetic force and the weak force. So
once you bring in the Higgs field, you can combine two of the forces into one. So it turns out the
electromagnetic force and the weak force are just two aspects of the same fundamental force.
And at the LHC, we go to high enough energies that you see these two forces
unifying effectively.
So first of all, it started as a theoretical notion. And then,
I mean, wasn't the Higgs called the God particle at some point?
It was by a guy trying to sell popular science books. Yeah.
Yeah, but I mean, I remember because when I was hearing it, I thought it would,
I mean, that would solve a lot of the, unify a lot of our ideas of physics. It was my notion.
But maybe you can speak to that. Is it as big of a leap? Is it as a God particle? Is it Jesus
particle? Which, you know, what's the big contribution of Higgs in terms of this unification power?
Yeah. I mean, to understand that, it maybe helps to know the history a little bit. So
when the, what we call electroweak theory was put together, which is where you unify
electromagnetism with the weak force and Higgs is involved in all of that. So that theory,
which was written in the mid-70s, predicted the existence of four new particles, the W plus
boson, the W minus boson, the Z boson and the Higgs boson. So there were these four particles
that came with the theory that were predicted by the theory. In 1983-84, the Ws and the Z
particles were discovered at an accelerator at CERN called the super proton synchrotron,
which was a seven kilometer particle collider. So three of the bits of this theory had already
been found. So people were pretty confident from the 80s that the Higgs must exist because it was
a part of this family of particles that this theoretical structure only works if the Higgs is
there. So what then happens? So this question about why is the LHC the size it is? Well,
actually, the tunnel that the LHC is in was not built for the LHC. It was built for a previous
accelerator called the large electron positron collider. So that began operation in the late
80s, early 90s. Basically, that's when they dug the 27 kilometer tunnel, they put this accelerator
into it, the collider that fires electrons and anti electrons at each other, electrons and positrons.
So the purpose of that machine was, well, it was actually to look for the Higgs. That was one of
the things it was trying to do. It didn't have enough energy to do it in the end. But the main
thing it achieved was it studied the W and the Z particles at very high precision. So it made loads
of these things. Previously, you can only make a few of them at the previous accelerator. So you
could study these really, really precisely. And by studying their properties, you could really test
this electoral week theory that had been invented in the 70s and really make sure that it worked. So
actually by 1999, when this machine turned off, people knew, well, okay, you never know until
you find the thing. But people were really confident this electoral week theory was right.
And that the Higgs almost, the Higgs or something very like the Higgs had to exist, because otherwise
the whole thing doesn't work. It'd be really weird if you could discover and these particles,
they all behave exactly as the theory tells you they should. But somehow this key piece of the
picture is not there. So in a way, it depends how you look at it. The discovery of the Higgs on its
own is obviously a huge achievement in many both experimentally and theoretically. On the other
hand, it's this, it's like having a jigsaw puzzle where every piece has been filled in. You have
this beautiful image, there's one gap and you kind of know that that piece must be there somewhere.
Right. So the discovery in itself, although it's important, is not so interesting.
It's like a confirmation of the obvious at that point.
But what makes it interesting is not that it just completes the standard model,
which is a theory that we've known had the basic layout of for 40 years or more now.
It's that the Higgs actually is a unique particle is very different to any of the other
particles in the standard model. And it's a theoretically very troublesome particle. There
are a lot of nasty things to do with the Higgs, but also opportunities. So that we basically,
we don't really understand how such an object can exist in the form that it does. So there are lots
of reasons for thinking that the Higgs must come with a bunch of other particles, or that it's
perhaps made of other things. So it's not a fundamental particle that it's made of smaller
things. I can talk about that if you like a bit. That's still a notion. So the Higgs might not be
a fundamental particle. There might be some, oh man. So that is an idea. It's not been demonstrated
to be true. But I mean, all of these ideas basically come from the fact that this is a
problem that motivated a lot of development in physics in the last 30 years or so. And there's
this basic fact that the Higgs field, which is this field that's everywhere in the universe,
this is the thing that gives mass to the particles. And the Higgs field is different from all the
other fields in that, let's say you take the electromagnetic field, which is, you know,
if we actually were to measure the electromagnetic field in this room, we would measure all kinds
of stuff going on because there's light, there's going to be microwaves and radio waves and stuff.
But let's say we could go to a really, really remote part of empty space and shield it and put a big
box around it and then measure the electromagnetic field in that box. The field would be almost zero,
apart from some little quantum fluctuations, but basically it goes to naught. The Higgs field has
a value everywhere. So it's a bit like the whole, it's like the entire space has got this energy
stored in the Higgs field, which is not zero, it's finite. It's got some, it's a bit like having the
temperature of space raised to, you know, some background temperature. And it's that energy
that gives mass to the particles. So the reason that electrons and quarks have mass is through the
interaction with this energy that's stored in the Higgs field. Now, it turns out that the
precise value this energy has, has to be very carefully tuned if you want a universe where
interesting stuff can happen. So if you push the Higgs field down, it has a tendency to collapse to
if you do your sort of naive calculations, there are basically two possible likely configurations
for the Higgs field, which is either it's zero everywhere, in which case you have a universe
which is just particles with no mass that can't form atoms and just fly about at the speed of light,
or it explodes to an enormous value, what we call the Planck scale, which is the scale of
quantum gravity. And at that point, if the Higgs field was that strong, even an electron would
become so massive that it would collapse into a black hole. And then you have a universe made of
black holes and nothing like us. So it seems that the strength of the Higgs field is to achieve the
value that we see requires what we call fine tuning of the laws of physics. You have to fiddle
around with the other fields in the standard model and their properties to just get it to this right
sort of Goldilocks value that allows atoms to exist. This is deeply fishy. People really dislike
this. So two explanations. One, there's a God that designed this perfectly and two is
there's an infinite number of alternate universes and we're just
happening to be in the one in which life is possible, complexity. So when you say life,
any kind of complexity, that's not either complete chaos or black holes. How does that
make you feel? What do you make of that? That's such a fascinating notion that this perfectly
tuned field that's the same everywhere is there. What do you make of that? Yeah, what do you make
of that? I mean, yeah, so you laid out two of the possible explanations. I mean, some cosmic
creator went, yeah, let's fix that to be at the right level. That's one possibility, I guess.
It's not a scientifically testable one. But theoretically, I guess it's possible.
Sorry to interrupt, but there could also be not a designer, but couldn't there be just,
I guess I'm not sure what that would be, but some kind of force that
some kind of mechanism by which this kind of field is enforced in order to create complexity.
Basically, forces that pull the universe towards an interesting complexity.
I mean, yeah, I mean, there are people who have those ideas. I don't really subscribe to them.
As I'm saying, it sounds really stupid. No, I mean, there are definitely people that make those
kind of arguments. There's ideas that, I think it's Lee Smolin's idea, I think that universes
are born inside black holes. And so universes, they basically have like Darwinian evolution
of the universe where universes give birth to other universes. And the universes where black
holes can form are more likely to give birth to more universes. So you end up with universes which
have similar laws. I mean, I don't know, whatever. Well, I talked to Lee recently on this podcast,
and he's a reminder to me that the physics community has like so many interesting characters.
It's fascinating. Anyway, sorry. So I mean, as an experimentalist, I tend to sort of think,
these are interesting ideas, but they're not really testable. So I tend not to think about
them very much. So, I mean, going back to the science of this, there is an explanation. There
is a possible solution to this problem of the Higgs, which doesn't involve multiverses or creators
fiddling about with the laws of physics. If the most popular solution was something called
supersymmetry, which involves a new type of symmetry of the universe. In fact, it's one of
the last types of symmetries that it's possible to have that we haven't already seen in nature,
which is a symmetry between force particles and matter particles. So what we call fermions,
which are the four, the matter particles and bosons, which are force particles.
And if you have supersymmetry, then there is a superpartner for every
particle in the standard model. And without going into the details, the effect of this basically
is that you have a whole bunch of other fields. And these fields cancel out the effect of the
standard model fields, and they stabilize the Higgs field at a nice sensible value. So in
supersymmetry, you naturally, without any tinkering about with the constants of nature or
anything, you get Higgs field with a nice value, which is the one we see. So this is one of the
and supersymmetry is also got lots of other things going for it. It predicts the existence of a dark
matter particle, which would be great. It, you know, it potentially suggests that the strong
force and the electoral weak force unify high energy. So lots of reasons people thought this
was a productive idea. And when the LHC was just before it was turned on, there was a lot of hype,
I guess, a lot of an expectation that we would discover these superpartners because particularly
the main reason was that if supersymmetry stabilizes the Higgs field at this nice Goldilocks value,
these superparticles should have a mass around the energy that we're probing at the LHC around
the energy of the Higgs. So it was kind of thought you discover the Higgs, you probably discover
superpartners as well. So once you start creating ripples in this Higgs field, you should be able
to see these kinds of, you should be, yeah. These superfields will be there. And when I,
at the very beginning, I said, we're probing the vacuum. What I mean is really that, you know,
okay, let's say these superfields exist, the vacuum contains superfields, they're there,
these supersymmetric fields. If we hit them hard enough, we can make them vibrate,
we see superparticles come flying out. That's the sort of, that's the idea.
That's the whole, okay. That's the whole point.
We haven't.
But we haven't. So far, at least, I mean, we've had now a decade of data taking at the LHC.
No signs of superpartners have supersymmetric particles have been found. In fact, no signs of
any physics, any new particles beyond the standard model have been found. So supersymmetry is not
the only thing that can do this. There are other theories that involve additional dimensions of
space or potentially involve the Higgs boson being made of smaller things, being made of
other particles.
That's an interesting, you know, I haven't heard that before. That's really,
that's an interesting book. Could you maybe linger on that? Like what,
what could be, what could the Higgs particle be made of?
Well, so the oldest, I think the original ideas about this was these theories called
technicolor, which were basically like an analogy with the strong force. So the idea was the Higgs
boson was a bound state of two very strongly interacting particles that were a bit like
quarks. So like quarks, but I guess higher energy things with a super strong force and not the
strong force, but a new force that was very strong. And the Higgs was a bound state of,
of these, these objects. And the Higgs one principle, if that was right, would be the
first in a series of technicolor particles. Technicolor, I think not being a theorist,
but it's not, it's basically not done very well, particularly since the LHC found the Higgs that
kind of, it rules out, you know, a lot of these technicolor theories, but there are other things
that are a bit like technicolor. So there's a theory called partial compositeness, which is an
idea that some of my colleagues at Cambridge have worked on, which is a similar sort of idea that
the Higgs is a bound state of some strongly interacting particles, and that the standard
model particles themselves, the more exotic ones like the top quark are also sort of mixtures of
these composite particles. So it's a kind of an extension to the standard model, which explains
this problem with the Higgs bosons, Goldilocks value, but also helps us understand we have,
we're in this situation now, again, a bit like the periodic table where we have six quarks,
six leptons in this kind of, you can arrange in this nice table and you can see these columns
where the patterns repeat and you go, okay, maybe there's something deeper going on here,
and so this would potentially be something, this partial compositeness theory could explain
a sort of enlarge this picture that allows us to see the whole symmetrical pattern and understand
what the ingredients, why do we have, so one of the big questions in particle physics is, why are
there three copies of the matter particles? So in what we call the first generation, which is what
we're made of, there's the electron, the electron neutrino, the up quark and the down quark, they're
the most common matter particles in the universe, but then there are copies of these four particles
in the second and the third generations, so things like muons and top quarks and other stuff.
We don't know why, we see these patterns, we have no idea where it comes from, so that's
another big question, can we find out the deeper order that explains this particular
periodic table of particles that we see? Is it possible that the deeper order includes
like almost a single entity? So like something that I guess like string theory dreams about,
is this essentially the dream, is to discover something simple, beautiful and unifying?
Yeah, I mean, that is the dream. And I think for some people, for a lot of people, it still is
the dream. So there's a great book by Stephen Weinberg, who is one of the theoretical physicists
who was instrumental in building the standard model. So he came up with some others with the
electroweak theory, the theory that unified electromagnetism and the weak force. And he
wrote this book, I think it was towards the end of the 80s, early 90s, called Dreams of a Final
Theory, which is a very lovely, quite short book about this idea of a final unifying theory that
brings everything together. And I think you get a sense reading his book written at the end of the
80s and early 90s, that there was this feeling that such a theory was coming. And that was the
time when string theory was very exciting. So string theory, there's been this thing called
the super string revolution. And theoretical physics getting very excited, they discovered
these theoretical objects, these little vibrating loops of string that in principle, not only was
a quantum theory of gravity, but could explain all the particles in the standard model and bring
it all together. And as you say, you have one object, the string, and you can pluck it. And
the way it vibrates gives you these different notes, each of which is a different particle.
So it's a very lovely idea. But the problem is that there's a few people discover the
mathematics is very difficult. So people have spent three decades and more trying to understand
string theory. And I think, you know, if you spoke to most string theorists, they would probably
freely admit that no one really knows what string theory is. Yeah, I mean, there's been a lot of
work, but it's not really understood. And the other problem is that string theory mostly makes
predictions about physics that occurs at energies far beyond what we will ever be able to probe
in the laboratory. Yeah, probably ever. By the way, sorry, take a million tangents, but
is there room for complete innovation of how to build a particle collider that could give us an
order of magnitude increase in the kind of energies? Or do we need to keep just increasing
the size of things? I mean, maybe, yeah, I mean, there are ideas to give you a sense of the gulf
that has to be bridged. So the LHC collides particles at an energy of what we call 14 terat
electron volts. So that's basically equivalent of you've accelerated a proton through 14 trillion
volts. That gets us to the energies where the Higgs and these weak particles live. They're
very massive. The scale where strings become manifest is something called the Planck scale,
which I think is of the order 10 to the, hang on, get this right, it's 10 to the 18 giga
electron volts, so about 10 to the 15 terat electron volts. So you're talking, you know,
trillions of times more energy. Yeah, 10 to the 15 or 10 to the 14th larger.
I may be wrong, but it's a very big number. So, you know, we're not talking just an order
of magnitude increase in energy, we're talking 14 orders of magnitude energy increase. So to
give you a sense of what that would look like, were you to build a particle accelerator with
today's technology? Bigger or smaller than our solar system?
As the size of the galaxy? The galaxy.
So you need to put a particle accelerator that circled the Milky Way to get to the energies
where you would see strings if they exist. So that is a fundamental problem, which is that
most of the predictions of the unified, these unified theories, quantum theories of gravity,
only make statements that are testable at energies that we will not be able to probe,
barring some unbelievable, you know, completely unexpected technological or scientific breakthrough,
which is almost impossible to imagine. You never say never, but it seems very unlikely.
Yeah, I can just see the news story. Elon Musk decides to build
a particle collider the size of our... We'd have to get together with all our
galactic neighbors to pay for it, I think. What is the exciting possibilities of the
Large Hadron Collider? What is there to be discovered in this order of magnitude of scale?
Is there other bigger efforts on the horizon in this space? What are the open problems,
exciting possibilities? You mentioned supersymmetry.
Yeah. So, well, there are lots of new ideas. Well, there are lots of problems that we're
facing. So there's a problem with the Higgs field, which supersymmetry was supposed to solve.
There's the fact that 95% of the universe we know from cosmology, astrophysics is invisible,
that it's made of dark matter and dark energy, which are really just words for things that we
don't know what they are. It's what Donald Rumsfeld called a known unknown. So we know we don't know
what they are. Well, that's better than unknown unknown. Yeah, well, there may be some unknown
unknowns, but we don't know what those are. But the hope is a particle accelerator could help us
make sense of dark energy, dark matter. There's some hope for that.
There's hope for that. Yeah. So one of the hopes is the LHC could produce a dark matter particle
in its collisions. And it may be that the LHC will still discover new particles,
that it might still supersymmetry could still be there. It's just maybe more difficult to find
than we thought originally. And dark matter particles might be being produced, but we're
just not looking in the right part of the data for them. That's possible. It might be that we
need more data, that these processes are very rare, and we need to collect lots and lots of data
before we see them. But I think a lot of people would say now that the chances of the LHC
directly discovering new particles in the near future is quite slim. It may be that we need
a decade more data before we can see something or we may not see anything. That's where we are.
So I mean, the physics, the experiments that I work on, so I work on a detector called LHCB,
which is one of these four big detectors that are spaced around the ring. And we do slightly
different stuff to the big guys. There's two big experiments called Atlas and CMS,
3,000 physicists and scientists and computer scientists on them, each, they are the ones
that discovered the Higgs and they look for supersymmetry and dark matter and so on.
What we look at are standard model particles called bequarks,
which depending on your preference is either bottom or beauty. We tend to say beauty because
it sounds sexier. But these particles are interesting because we can make lots of them.
We make billions or billions, hundreds of billions of these things. You can therefore
measure their properties very precisely. So you can make these really lovely precision measurements.
And what we are doing really is a sort of complementary thing to the other big experiments,
which is they, if you think of the silver analogy that often uses, if imagine you're
looking in, you're in the jungle and you're looking for an elephant, say, and you are a hunter
and you're kind of like, let's say there's the relevance very rare, you don't know where in
the jungle, the jungle's big. So there's two ways you go about this. Either you can go
wandering around the jungle and try and find the elephant. The problem is if the elephant,
if there's any one elephant in the jungle's big, the chances of running into it are very small.
Or you could look on the ground and see if you see footprints left by the elephant. And if the
elephant's moving around, you've got a chance that your better chance maybe of seeing the
elephant's footprints. If you see the footprints, you go, okay, there's an elephant, I maybe don't
know what kind of elephant it is, but I got a sense there's something out there. So that's
sort of what we do. We are the footprint people. We are, we're looking for the footprints, the
impressions that quantum fields that we haven't managed to directly create the particle of,
the effects these quantum fields have on the ordinary standard model fields that we already
know about. So these B particles, the way they behave can be influenced by the presence of,
say, super fields or dark matter fields or whatever you like. And the way they decay and
behave can be altered slightly from what our theory tells us they ought to behave.
Got you. And it's easier to collect huge amounts of data on B quarks.
We get, you know, billions and billions of these things. You can make very precise measurements.
And the only place really at the LHC or in really in high-energy physics at the moment,
where there's fairly compelling evidence that there might be something beyond the
standard model is in these B, these beauty quarks decays.
Just to clarify, which is the difference between the four experiments, for example,
that you mentioned, is it the kind of particles that are being collided? Is it the energies
of which they're collided? What's the fundamental difference between the different experiments?
The collisions are the same. What's different is the design of the detectors. So
Atlas and CMS are called, they're called what are called general purpose detectors.
And they are basically barrel-shaped machines. And the collisions happen in the middle of the
barrel. And the barrel captures all the particles that go flying out in every direction. So in a
sphere, effectively, that can fly out and it can record all of those particles.
And what's the, sorry to be interrupting, but what's, what's the mechanism of the recording?
Oh, so these detectors, if you've seen pictures of them, they're huge, like Atlas is 25 meters high
and 45 meters long. They're vast machines, instruments, I guess you should call them really.
They are, they're kind of like onions. So they have layers, concentric layers of detector,
detectors, different sorts of detector. So close into the beam pipe, you have what are called
usually made of silicon, they're tracking detectors. So they're little made of strips of
silicon or pixels of silicon. And when a particle goes through the silicon, it gives a little
electrical signal. And you get these dots, you know, electrical dots through your detector,
which allows you to reconstruct the trajectory of the particle. So that's the middle. And then the
outsides of these detectors, you have things called calorimeters, which measure the energies of the
particles. And on the very edge, you have things called muon chambers, which basically met these
muon particles, which are the heavy version of the electron, they are, they're like high-velocity
bullets, and they can get right to the edge of the detector. So if you see something at the
edge, that's a muon. So that's broadly how they work. And all of that is being recorded. That's
all being fed out to, you know, computers. That data must be awesome. Okay. So LHCB is different.
So we, because we're looking for these bequarks, bequarks tend to be produced along the beam
line. So in a collision, the bequarks tend to fly sort of close to the beam pipe. So we built the
detector that sort of pyramid cone-shaped, basically, that just looks in one direction. So we ignore,
if you have your collision, stuff goes everywhere. We ignore all the stuff over here and going off
sideways. We're just looking in this little region close to the beam pipe where most of these bequarks
are made. So is there a different aspect of the sensors involved in the collection of the bequark
trajectories? There are some differences. So one of the differences is that one of the ways you
know you've seen a bequark is that bequarks are actually quite long-lived by particle standards.
So they live for 1.5 trillionths of a second, which is if you're a fundamental particle,
it's a very long time. Because, you know, the Higgs boson, I think lives for about a trillionth
of a trillionth of a second, or maybe even less than that. So these are quite long-lived things.
And they will actually fly a little distance before they decay. So they will fly, you know,
a few centimeters, maybe, if you're lucky, then they'll decay into other stuff. So what we need
to do in the middle of the detector, you want to be able to see, you have your place where the
protons crash into each other, and that produces loads of particles that come flying out. So you
have loads of lines, loads of tracks that point back to that proton collision. And then you're
looking for a couple of other tracks, maybe two or three, that point back to a different place
that's maybe a few centimeters away from the proton collision. And that's the sign that
a little B particle has flown a few centimeters and decayed somewhere else. So we need to be able
to very accurately resolve the proton collision from the B particle decay. So the middle of our
detector is very sensitive, and it gets very close to the collision. So you have this really
beautiful, delicate silicon detector that sits, I think it's seven millimeters from the beam.
And the LHC beam has as much energy as a jumbo jet at takeoff. So it's enough to melt a ton of
copper. So you have this furiously powerful thing sitting next to this tiny, delicate, you know,
silicon sensor. So those aspects of our detector that are specialized to
measure these particular B quarks that we're interested in.
And is there, I mean, I remember seeing somewhere that there's some mention of matter and antimatter
connected to the B, these beautiful quarks. Is that, what's the connection,
yeah, what's the connection there?
Yeah. So there is a connection, which is that when you produce these B particles,
these particles, because you don't see the B quark, you see the thing that B quark is inside.
So they're bound up inside what we call beauty particles, where the B quark is joined together
with another quark or two, maybe two other quarks, depending on what it is. There are a particular
set of these B particles that exhibit this property called oscillation. So if you make a,
for the sake of argument, a matter version of one of these B particles, as it travels,
because of the magic of quantum mechanics, it oscillates backwards and forwards between its
matter and antimatter versions. So it does this weird flipping about backwards and forwards.
And what we can use this for is a laboratory for testing the symmetry between matter and
antimatter. So if the symmetry between antimatter is precise, it's exact, then we should see these
B particles decaying as often as matter as they do as antimatter, because this oscillation should
be even. It should spend as much time in each state. But what we actually see is that one of
the states, it spends more time in, it's more likely to decay in one state than the other.
So this gives us a way of testing this fundamental symmetry between matter and antimatter.
So what can you sort of return to the question before about this fundamental symmetry? It seems
like if this perfect symmetry between matter and antimatter, if we have the equal amount
of each in our universe, it would just destroy itself. And just like you mentioned, we seem to
live in a very unlikely universe where it doesn't destroy itself. So do you have some
intuition about why that is? I mean, well, I'm not a theory. I don't have any particular ideas
myself. I mean, I sort of do measurements to try and test these things. But I mean, so the
terms of the basic problem is that in the Big Bang, if you use the standard model to figure
out what ought to have happened, you should have got equal amounts of matter and antimatter made,
because whenever you make a particle in our collisions, for example, when we collide stuff
together, you make a particle, you make an antiparticle, they always come together,
they always annihilate together. So there's no way of making more matter than antimatter
that we've discovered so far. So that means in the Big Bang, you get equal amounts of matter
antimatter. As the universe expands and cools down during the Big Bang, not very long after
the Big Bang, I think a few seconds after the Big Bang, you have this event called the Great
Annihilation, which is where all the particles and antiparticles smack into each other, annihilate,
turn into light mostly, and you end up with a universe later. If that was what happened,
then the universe we live in today would be black and empty, apart from some photons, that would
be it. So there's stuff in the universe, it appears to be just made of matter. So there's
this big mystery as to how did this happen? And there are various ideas which all involve
sort of physics going on in the first trillionth of a second or so of the Big Bang. So it could be
that one possibility is that the Higgs field is somehow implicated in this, that there was this
event that took place in the early universe where the Higgs field basically switched on,
it acquired its modern value. And when that happened, this caused all the particles to
acquire mass and the universe basically went through a phase transition where you had
a hot plasma of massless particles. And then in that plasma, it's almost like a gas turning
into droplets of water. You get kind of these little bubbles forming in the universe where the
Higgs field has acquired its modern value, the particles have got mass. And this phase transition
in some models can cause more matter than antimatter to be produced, depending on
how matter bounces off these bubbles in the other universe. So that's one idea. There's
other ideas to do with neutrinos that there are exotic types of neutrinos that can decay
in a biased way to just matter and not to antimatter. And people are trying to test these
ideas. That's what we're trying to do at LHCB. There's neutrino experiments planned that are
trying to do these sorts of things as well. So yeah, there are ideas, but at the moment no
clear evidence for which of these ideas might be right. So we're talking about some incredible
ideas. By the way, never heard anyone be so eloquent about describing even just the standard
model. So I'm in awe, just having fun enjoying it. So yes, the theoretical, the particle physics
is fascinating here. To me, one of the most fascinating things about the Large Hadron Collider
is the human side of it. That a bunch of sort of brilliant people that probably have egos
got together and were collaborate together and countries, I guess, collaborate together for
the funds and just collaboration everywhere. Because you're maybe, I don't know what the
right question here to ask, but what's your intuition about how is possible to make this
happen? And what are the lessons we should learn for the future of human civilization in terms of
our scientific progress? Because it seems like this is a great, great illustration of us working
together to do something big. Yeah, I think it's possibly the best example, maybe I can think of
of international collaboration that isn't for some unpleasant purpose, basically. When I started
out in the field in 2008 as a new PhD student, the LHC was basically finished. So I didn't have to
go around asking for money for it or trying to make the case. So I have huge admiration for
the people who managed that because this was a project that was first imagined in the 1970s.
In the late 70s was when the first conversations about the LHC were mooted and it took
two and a half decades of campaigning and fundraising and persuasion until they started
breaking ground and building the thing in the early 90s and 2000. So I mean, I think the reason,
just from a sort of, from the point of view of the sort of science, the scientists there, I think
the reason it works ultimately is that everywhere, everyone there is there for the same reason,
which is, well, in principle, at least, they're there because they're interested in the world.
They want to find out, you know, what are the basic ingredients of our universe? What are the laws of
nature? And so everyone is pulling in the same direction. Now, of course, everyone has their
own things they're interested in. Everyone has their own careers to consider. And, you know,
I wouldn't pretend that there isn't also a lot of competition. So this is funny thing in these
experiments where your collaborators, your 800 collaborators in LHCB, but you're also competitors
because your academics in your various universities, and you want to be the one that gets the paper
out on the most exciting, you know, new measurements. So there's this funny thing where you're kind of
trying to stake out your territory while also collaborating and having to work together to
make the experiments work. And it does work amazingly well, actually, considering all of that.
And I think there was actually, I think McKinsey or one of these big management consultancy firms
went into CERN maybe a decade or so ago to try to understand how these organizations functioned.
Did they figure it out? I don't think they could. I mean, I think one of the things that's interesting,
one of the other interesting things about these experiments is they're big operations,
like say Atlas has 3,000 people. Now, there was a person nominally who is the head of Atlas,
they're called the spokesperson. And the spokesperson is elected by usually by the collaboration,
but they have no actual power, really. I mean, they can't fire anyone. They're not anyone's boss.
So, you know, my boss is a professor at Cambridge, not the head of my experiments. The head of my
experiment can't tell me what to do really. And I mean, there's all these independent academics
who are their own bosses who, you know, so that somehow it nonetheless, by kind of consensus and
discussion and lots of meetings, these, you know, things do happen and it does get done.
But it's like the queen here in the UK is the spokesperson. Except we don't elect her.
No, we don't elect her. But everybody seems to love her. I don't know, from my outside perspective.
But yeah, giant egos, brilliant people, and moving forward, do you think there's...
Actually, I would pick up one thing you said just there, just the brilliant people thing,
because I'm not saying that people aren't great. But I think there is this sort of
impression that physicists all have to be brilliant or geniuses, which is not true,
actually. And you have to be relatively bright for sure. But a lot of people, a lot of the most
successful experimental physicists are not necessarily the people with the biggest brains.
They're the people who, particularly one of the skills that's most important in particle
physics is the ability to work with others and to collaborate and exchange ideas and also to work
hard. And it's a sort of, often it's more a determination or a sort of other set of skills
is not just being kind of some great brain. Very true. So I mean, there's parallels to
that in the machine learning world. If you want to solve any real world problems,
which I see as the particle accelerators, essentially a real world instantiation of
theoretical physics. And for that, you have to not necessarily be brilliant, but be sort of
obsessed, systematic, rigorous, sort of unboreable, stubborn, all those kind of qualities that make
for a great engineer. So there's scientists purely speaking that practitioner of the scientific
method. So you're right. But nevertheless, to me, that's brilliant. My dad's a physicist.
I argue with him all the time. To me, engineering is the highest form of science. And he thinks
that's all nonsense that the real work is done by the theoretician. So he, in fact, we have arguments
about like people like Elon Musk, for example, because I think his work is quite brilliant,
but he's fundamentally not coming up with any serious breakthroughs. He's just creating in
this world, implementing ideas, like making ideas happen to have a huge impact. To me, that is,
that's the Edison that, to me, is a brilliant work. But to him, it's messy details that somebody
will figure out anyway. I mean, I don't know whether you think there is an actual difference
in temperament between, say, a physicist and an engineer, whether it's just what you got interested
in. I don't know. I mean, a lot of what experimental physicists do is, to some extent,
engineering. I mean, it's not what I do. I mostly do data stuff. But you know,
a lot of people would be called electrical engineers, but they trained as physicists,
but they learned electrical engineering, for example, because they were building detectors.
So there's not such a clear divide, I think. Yeah, that's interesting. I mean, there does seem
to be like you work with data. There does seem to be a certain, like I love data collection.
There might be an OCD element or something that you're more naturally predisposed to,
as opposed to theory. Like, I'm not afraid of data. I love data. And there's a lot of people in
machine learning who are more, like, they're basically afraid of data collection, afraid
of data sets, afraid of all of that. They just want to stay more in the theoretical and they're
really good at it space. So I don't know if that's the genetic that you're all bringing the way you
go to school, but looking into the future of LHC and other colliders. So there's in America,
there was the, whatever it was called, the super, there's a lot of superconducting super
collider, the desertron desertron. So that was canceled, the construction of that,
which is a sad thing. But what do you think is the future of these efforts? Will a bigger collider
be built? Will LHC be expanded? What do you think? Well, in the near future, the LHC is
going to get an upgrade. So that's pretty much confirmed. I think it is confirmed, which is,
it's not an energy upgrade, it's what we call a luminosity upgrade. So it basically means
increasing the data collection rate, so more collisions per second, basically. Because
after a few years of data taking, you get this law of diminishing returns where each year's
worth of data is a smaller and smaller fraction of the lot you've already got. So to get a real
improvement in sensitivity, you need to increase the data rate by an order of magnitude. So that's
what this upgrade is going to do. LHCB at the moment, the whole detector is basically being
rebuilt to allow it to record data at a much larger rate than we could before. So that will
make us sensitive to whole loads of news processes that we weren't able to study before. And I
mentioned briefly these anomalies that we've seen. So we've seen a bunch of very intriguing
anomalies in these B quark decays, which may be hinting at the first signs of this kind of the
elephant, the signs of some new quantum field or fields maybe beyond the standard model. It's not
yet at the statistical threshold where you can say that you've observed something. But there's
lots of anomalies in many measurements that all seem to be consistent with each other. So it's
quite interesting. So the upgrade will allow us to really home in on these things and see whether
these anomalies are real. Because if they are real, and this connects to your point about the
next generation of machines, what we will have seen then is we will have seen the tail end of some
quantum field in influencing these B quarks. What we then need to do is to build a bigger
collider to actually make the particle of that field. So if these things really do exist,
so that would be one argument. So at the moment, Europe is going through this process of
thinking about the strategy for the future. So there are a number of different proposals on
the table. One is for a higher energy upgrade of the LHC where you just build more powerful magnets
and put them in the same tunnel. That's a cheaper, less ambitious possibility. Most people don't
really like it because it's a bit of a dead end. Because once you've done that, there's nowhere
to go. There's a machine called CLIC, which is a compact linear collider, which is an electron
positron collider that uses a novel type of acceleration technology to accelerate at shorter
distances. We're still talking kilometers long, but not like 100 kilometers long. And then probably
the project that is, I think, getting the most support, it'll be interesting to see what happens,
something called the future circular collider, which is a really ambitious long-term multi-decade
project to build a 100 kilometer circumference tunnel under the Geneva region. The LHC would
become a kind of feeding machine. It would just feed. So the same area, so it would be a feeder
for the LHC. Yeah. So the edge of this machine would be where the LHC is, but it would go under
Lake Geneva and round to the Alps, basically, up to the edge of the Geneva basin. So it's
basically the biggest tunnel you can fit in the region based on the geology.
The calamity.
Yeah. So it's big. It'd be a long drive if you're experiments on one side. You've got to go back
to CERN for lunch, so that will be a pain. So this project is, in principle, is actually two
accelerators. The first thing you would do is put an electron positron machine in the 100 kilometer
tunnel to study the Higgs. You'd make lots of Higgs bosons, study it really precisely,
in the hope that you see it misbehaving and doing something it's not supposed to.
And then in the much longer term, 100, that machine gets taken out. You put in a proton-proton
machine. So it's like the LHC, but much bigger. Much bigger. And that's the way you start going
and looking for dark matter, or you're trying to recreate this phase transition that I talked
about in the early universe, where you can see matter-antimatter being made, for example. There
are lots of things you can do with these machines. The problem is that the most optimistic, you're
not going to have any data from any of these machines until 2040, because they take such a
long time to build and they're so expensive. So there'll be a process of R&D design,
but also the political case being made. So LHC, what costs a few billion?
Depends how you count it. I think most of the more reasonable estimates that take everything
into account properly, it's around the sort of 10, 11, 12 billion euro mark.
What would be the future, sorry, I forgot the name already.
Future circular collider.
Future circular collider.
Presumably they won't call it that when it's built, because it won't be the future anymore,
but I don't know what they'll call it then.
Very big hadron collider, I don't know. But that will, I don't know, I should know the numbers,
but I think the whole project is estimated at about 30 billion euros, but that's money spent over
between now and 2070, probably, which is when the last bit of it would be sort of finishing up,
I guess. So you're talking half a century of science coming out of this thing,
shared by many countries. So the actual cost, the arguments that are made is that you could
make this project fit within the existing budget of CERN, if you didn't do anything else.
And CERN, by the way, we didn't mention. What is CERN?
CERN is the European Organization for Nuclear Research. It's an international
organization that was established in the 1950s in the wake of the Second World War as a kind of,
it was sort of like a scientific Marshall plan for Europe. The idea was that you bring European
science back together for peaceful purposes, because what happened in the 40s was a lot of,
particularly a lot of Jewish scientists, but a lot of scientists from Central Europe had fled to
the United States, and Europe had sort of seen this brain drain. So it was a desire to bring
the community back together for a project that wasn't building nasty bombs, but was doing something
that was curiosity driven. And that has continued since then. So it's kind of a unique organization.
To be a member as a country, you sort of sign up as a member, and then you have to pay a
fraction of your GDP each year as a subscription. I mean, it's a very small fraction, relatively
speaking, I think it's like, I think the UK's contribution is 100 or 200 million quid or something
like that, which is quite a lot, but not that's fascinating. I mean, just the whole thing that
is possible. It's a beautiful idea, especially when there's no wars on the line, it's not like
we're freaking out, we're actually legitimately collaborating to do good science. One of the
things I don't think we really mentioned is on the final side, that sort of the data analysis side,
is there breakthroughs possible there in the machine learning side? Like, is there a lot more
signal to be mined in more effective ways from the actual raw data? Yeah, a lot of people are
looking into that. I mean, so I use machine learning in my data analysis, but pretty noddy,
basic stuff, because I'm not a machine learning expert, I'm just a physicist who had to learn to
do this stuff for my day job. So what a lot of people do is they use kind of off the shelf
packages that you can train to do signal noise. Just clean up all the data. But one of the big
challenges is, you know, the big challenge of the data is, A, it's volume, there's huge amounts
of data. So the LHC generates, now, okay, I try to remember what the actual numbers are, but if you
we don't record all our data, we record a tiny fraction of the data, it's like of order 110,000th
or something, I think, is that right? Around that. So it's most of it gets thrown away, you
couldn't record all the LHC data because it would fill up every computer in the world in the matter
of days, basically. So there's this process that happens on live on the detector, something called
a trigger, which in real time, 40 million times every second has to make a decision about whether
this collision is likely to contain an interesting object like a pig's boson or a dark matter particle.
And it has to do that very fast. And the software algorithms in the past were quite
relatively basic, you know, they did things like measure momentas and energies of particles and
put some requirements. So you would say, if there's a particle with an energy above some threshold,
then record this collision. But if there isn't, don't. Whereas now the attempt is to get more
and more machine learning in at the earliest possible stage because cool at the stage of
deciding whether we want to keep this data or not. But also even even maybe even lower down than
that, which is the point where there's this, you know, so generally how the data is reconstructed
is you start off with a digital a set of digital hits in your detector. So channel saying, did you
see something? Do you not see something that has to be then turned into tracks, particles going in
different directions. And that's done by using fits that fit through the data points. And then
that's passed to the algorithms that then go, is this interesting or not? What would be better is
you could train machine learning to just look at the raw hits, the basic real basic level
information, not have any of the reconstruction done. And it just goes and you can learn to do
pattern recognition on this strange three dimensional image that you get. And potentially
that's where you could get really big gains because our triggers tend to be quite inefficient,
because they don't have time to do the full whiz bang processing to get all the information out
that we would like because you have to do the decision very quickly. So if you can come up with
some clever machine learning technique, then potentially you can massively increase the
amount of useful data you record and, you know, get rid of more of the background earlier in the
process. Yeah, to me, that's an exciting possibility because then you don't have to build a sort of
you can get a gain without having to. Without having to build any hardware, I suppose. Hardware,
yeah. You need lots of new GPU firms, I guess. So hardware still helps. But
you know, I gotta talk to you. I'm not sure how to ask, but you're clearly
an incredible science communicator. I don't know if that's the right term, but you're basically
a younger Neil deGrasse Tyson with a British accent. So and you've, I mean, can you say
where we are today, actually? Yeah. So today we're in the Royal Institution in London,
which is an old, very old organization. It's been around for about 200 years now,
I think, maybe even I should know when it was founded, but sort of early 19th century,
it was set up to basically communicate science to the public. So it was one of the first places
in the world where scientists, famous scientists would come and give talks. So very famously,
Humphrey Davy, who you may know of, who was the person who discovered nitrous oxide,
he was a very famous chemist and scientist, also discovered electrolysis. So he used to do these
fantastic, he was a very charismatic speaker. So he used to appear here, there's a big desk
that they usually have in the theater, and he would do demonstrations to the sort of the
folk of London back in the early 19th century. Michael Faraday, who I talked about, who was
the person who did so much work in electromagnetism, he used, he lectured here. He also did
experiments in the basement. So this place has got a long history of both scientific research,
but also communication of scientific research. So you gave a few lectures here, how many, two?
I've given a couple of lectures in this theater before. So people should definitely go watch
online. It's just the explanation of particle physics. It's incredible. Your lectures are just
incredible. I can't sing it enough praise. So it was awesome. But maybe can you say,
what does it feel like to lecture here, to talk about that? And maybe from a different
perspective, more kind of like how the sausage is made is, how do you prepare for that kind of
thing? How do you think about communication, the process of communicating these ideas in a way
that's inspiring to what I would say your talks are inspiring to like the general audience. You
don't actually have to be a scientist. You can still be inspired without really knowing much of
the, you start from the very basics. So what's the preparation process? And then the romantic
question is, what do that feel like to perform here? I mean, the profession. Yeah. I mean,
the process, I mean, the talk that my favorite talk that I gave here was one called beyond the
Higgs, which you can find on the, on the Royal Institute's YouTube channel, which you should
go and check out. I mean, and their channel's got loads of great talks, loads of great people as well.
I mean, that one, I sort of given a version of it many times. So part of it is just practice,
right? And actually, I don't have some great theory of how to communicate with people. It's
more just that I'm really interested and excited by those ideas. And I like talking about them.
And through the process of doing that, I guess I figured out stories that work and
explanations that work. When you say practice, you mean legitimately just giving, just giving
talks? Yeah. And I started off, you know, when I was a PhD student doing talks in schools. And
I still do that as well some of the time and doing things like I've even done a bit of stand-up comedy,
which was sort of went reasonably well, even if it was terrifying. And that's on YouTube as well.
That's also on you. I wouldn't necessarily recommend you check that out. I'm going to post
the link several places to make sure people click on it. Yeah. But it's basically, I kind of have
a story in my head. And I kind of, I have to think about what I want to say. I usually have some
images to support what I'm saying and I get up and do it. And it's not really, I wish there was
some kind of, I probably should have some proper process. This is very sounds like I'm just making
up as I go along. And I sort of am. Well, I think the fundamental thing that you said, I think,
it's like, I don't know if you know who a guy named Joe Rogan is. Yes, I do. So he, he's also
kind of sounds like you in a sense that he's not very introspective about his process, but he's
an incredibly engaging conversationalist. And I think one of the things that you and him share
that I could see is like a genuine curiosity and passion for the topic. I think that could be
systematically, you know, cultivated. I'm sure there's a process to it, but you come to it
naturally somehow. I think maybe there's something else as well, which is to understand something.
There's this quote by Feynman, which I really like, which is what I cannot create. I do not
understand. So like, I'm not, I'm not like particularly super bright. Like, so for me to
understand something, I have to break it down into its simplest elements. And that, you know,
and if I can then tell people about that, that helps me understand it as well. So I've actually,
I've learned, I've learned to understand physics a lot more from the process of communicating,
because it forces you to really scrutinize the ideas that you're communicating. Again,
it often makes you realize you don't really understand the ideas you're talking about.
And I'm writing a book at the moment, and I had this experience yesterday where I realized I didn't
really understand a pretty fundamental theoretical aspect of my own subject. And I had to go and I
had to sort of spend a couple of days reading textbooks and thinking about it in order to make
sure that the explanation I gave captured the, got as close to what is actually happening in the
theory. And to do that, you have to really understand it properly. And yeah, and there's layers to
understanding. Like it seems like the more, there must be some kind of Feynman law, I mean, the more
you understand sort of the simpler you're able to really convey the, you know, the essence of the
idea, right? So it's like this reverse, reverse effect that it's like, the more you understand,
the simpler, the final thing that you actually convey. And so the more accessible somehow it
becomes. That's why Feynman's lectures are really accessible. It was just counterintuitive.
Yeah. Although there are some ideas that are very difficult to explain, no matter how well
or badly you understand them. Like I still can't really properly explain the Higgs mechanism.
Because some of these ideas only exist in mathematics really. And the only way to really
develop an understanding is to go unfortunately to a graduate degree in physics. But you can get
kind of a flavor of what's happening, I think. And it's trying to do that in a way that isn't
misleading, but also intelligible. So let me ask them the romantic question of what to you
is the most perhaps an unfair question. What is the most beautiful idea in physics?
One that fills you with awe is the most surprising, the strangest, the weirdest. There's a lot of
the different definitions of beauty. And I'm sure there's several for you, but is there something
that just jumps to mind that you think is just especially? I mean, I, well, beautiful. There's
a specific thing in a more general thing. So maybe the specific thing first, which is I can
not have first came across as an undergraduate. I found this amazing. So this idea that the forces
of nature, electromagnetic and strong force, the weak force, they arise in our theories
as a consequence of symmetries. So symmetries in the laws of nature, in the equations,
essentially, that used to describe these ideas. The process whereby theories come up with these
sorts of models is they say, imagine the universe obeys particular type of symmetry is a symmetry
that isn't so far removed from a geometrical symmetry like the rotations of a cube. It's not,
you can't think of it quite that way, but it's sort of a similar sort of idea. And you say, okay,
if the universe respects the symmetry, you find that you have to introduce a force,
which has the properties of electromagnetism, or different symmetry, you get the strong force,
or different symmetry, you get the weak force. So these interactions seem to come from some
deeper, it suggests that they come from some deeper symmetry principle. I mean, depends a bit
how you look at it, because it could be that we're actually just recognizing symmetries in
the things that we see. But there's something rather lovely about that. But I mean, I suppose
a bigger thing that makes me wonder is actually, if you look at the laws of nature, how particles
interact when you get really close down, they're basically pretty simple things. They bounce off
each other by exchanging through force fields, and they move around in very simple ways. And
somehow, these basic ingredients, these few particles that we know about in the forces,
creates this universe, which is unbelievably complicated and has things like you and me in it,
and the earth and stars that make matter in their cause from the gravitational energy of
their own bulk that then gets sprayed into the universe that forms other things. I mean,
the fact that there's this incredibly long story that goes right back to the beginning,
we can take this story right back to a trillionth of a second after the Big Bang, and we can trace
the origins of the stuff that we're made from. And it all ultimately comes from these simple
ingredients with these simple rules. And the fact you can generate such complexity from that is
really mysterious, I think, and strange. And it's not even a question that physicists can really
tackle, because we are sort of trying to find these really elementary laws. But it turns out
that going from elementary laws and a few particles to something even as complicated as a molecule
becomes very difficult. So going from a molecule to a human being is a problem that just can't
be tackled, at least not at the moment. Yeah, the emergence of complexity from simple rules is so
beautiful and so mysterious. And we don't have good mathematics to even try to approach that
emergent phenomena. That's why we have chemistry and biology and all the other subjects as we
had, guys. I don't think there's a better way to end it, Harry. I think I speak for a lot of people
that can't wait to see what happens in the next five, 10, 20 years with you. I think you're one
of the great communicators of our time. So I hope you continue that. And I hope that grows. And
definitely a huge fan. So it was an honor to talk to you today. Thanks so much. Thanks very much.
Thanks for listening to this conversation with Harry Cliff. And thank you to our sponsors,
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And now let me leave you with some words from Harry Cliff. You and I are leftovers. Every
particle in our bodies is a survivor from an almighty shootout between matter and antimatter
that happened a little after the Big Bang. In fact, only one in a billion particles created
at the beginning of time have survived to the present day. Thank you for listening and hope to
see you next time.