Quantum Fields: The Real Building Blocks of the Universe – with David Tong

Quantum Fields: The Real Building Blocks of the Universe – with David Tong

Tonight, I’d like to
tell you about one of the big questions in science. It’s a question that
goes back at least two and a half thousand years,
to the ancient Greeks. And it’s a question that has
been discussed in this room many, many times over
the past 200 years, but it’s an important question. And I think it’s important
that we revisit it. And the question is simply this. It’s, what are we made of? What are the fundamental
building blocks of nature that you and me and everything
else in the universe are constructed from? That’s the story I’d
like to tell you. So what I’d like to do is
try and give you an overview of our current understanding. I’d also like to
try and give you an overview of where we hope
to go in the future, of what progress we can we can hope
to make in the next few years and few decades. And we’re going to cover quite
a lot of ground in this talk. I should warn you now,
not least because I’m going to discuss every
single thing in the universe, quite literally. We’re going to talk,
amongst other things, about what’s happening at the
world’s most powerful particle collider. This is a machine that’s called
the Large Hadron Collider, or the LHC for short. It’ll come up a
lot in this talk. And it’s a machine which
is based underground in a place called CERN which
is just outside Geneva. We’ll also talk
about experiments in the last few years that
look backwards in time towards the Big
Bang, that give us some understanding
about what was happening in the first few
fractions of a second after time itself
started to exist. And on top of all
this, I also want to give you some idea about
the theoretical abstract ideas, and even a little bit of an
idea about the mathematics that underlies our current
understanding of the universe. Because I’m a
theoretical physicist. What I do is study the
equations, try to understand the equations, that govern
the world we live in. And so, I’d just like to
give you a flavour of what that’s about. At some point– I
should warn you now. At some point, I’m even going
to show you an equation. You know, you can get
sent on training courses for this kind of thing. There’s a number one rule. The number one rule is never
show them any equations. If you show them equations,
you’ll just terrify them. At some point in
this lecture, you’re all going to be terrified,
so just prepare yourselves. OK? OK. You know, there’s a traditional
way to start talks like this. The traditional way
is to be very cultured and talk about what
Democritus and Lucretius said two and a half thousand
years ago and the ideas that the ancient
Greeks had about atoms. But you know, I don’t
want to start like this. We’ve made a lot of progress in
two and a half thousand years, and you know, there’s
just better places to kick off a science talk. So the first modern
picture that we had of what the universe is made
of, everything we’re made of, is this. So I hope this is familiar
to most people here. This is the periodic
table of elements. OK? It’s one of the most iconic
images in all of science. What we have here are
120-ish different elements. I should point out, no
less than 10 of which were discovered in this very
building, and which constitute, or at least in the
1800s were thought to constitute everything
that existed in nature. So it’s certainly true
that any material you get, you can distill it down
into its component parts, and you’ll find that all
of those component parts are made of one of
these 120 elements. So it’s a great
moment in science. It’s really one of the
triumphs of science. It’s also, I should add,
the reason that I stopped doing chemistry in school. Because if you’re a chemist,
this is basically as good as it gets. You know, if we’re honest,
it’s kind of a mess. Everything in the
universe is classified into things on the
left that go bang if you put them in water through
things on the right which, really if we’re honest,
don’t do very much at all. You kind of organise everything
into these stupid shapes. And it looks a little
bit like Australia. There’s a big dip in the
top, and then there’s these two strips of
elements that you have to put along the
bottom, because there’s no room for them in the
middle where they belong. You know, I don’t
know about you, if I was asked to come up with
a fundamental classification of everything in
the universe, this isn’t what I would
have gone for. Are there any chemists
in the audience? [LAUGHING] I’m sorry for you. OK. But you know, I’m
not alone in this. It’s not just me that
thinks this is a silly way to organise nature. Nature itself thinks this is a
silly way to organise nature. Of course, we know this
isn’t the fundamental– this isn’t the end of the story. This isn’t the fundamental
building blocks. And the first person to realise
there’s that there’s something deeper than this was a Cambridge
physicist called JJ Thomson. So at the end of the
1800s, JJ Thomson discovered a particle that
was smaller than an atom that we now call the electron. And in 1897, he announced
this in this room– in fact, in this very lecture series– to a stunned
audience, an audience that was so stunned
at least half of them didn’t believe
what he was saying. There was one very
distinguished scientist who afterwards told JJ Thomson
he thought the whole thing was a hoax, that JJ Thomson had
just been pulling their leg. But of course, it’s not a hoax. This isn’t the fundamental
elements of nature. And within 15 years of
JJ Thomson’s discovery, his successor in Cambridge, a
man called Ernest Rutherford, had figured out exactly what
these atoms are made of. And this is the picture that
Rutherford came up with. So we now know that
each of these elements consists of a nucleus,
which is tiny. The metaphor that Rutherford
himself used was it’s like a fly in the centre
of the cathedral. And then orbiting this
nucleus in, I should add, fairly blurry orbits,
are the electrons, which sort of fill out very
sparsely the rest of the space. So that’s a picture
of these atoms. Subsequently, we learned
that the nucleus is not itself fundamental. The nucleus contains
smaller particles. They’re particles that we
call protons and neutrons. And in the 1970s, we learned
that the protons and neutrons aren’t fundamental either. So in the 1970s, we learned that
inside each proton and neutron are three smaller particles
that we call quarks. There are two different
kinds of quarks. By the 1970s, I’m
guessing physicists didn’t have a classical
Greek education, and had kind of run
out of classy names. So we call these quarks the
up quark and the down quark. OK? For no good reason. It’s not like the up quark is
higher than the down quark. It’s not like it points up. Just no good reason at all. The up quark and the down quark. So the proton consists of two
up quarks and a down quark. And the neutron consists of two
down quarks and an up quark. This, as far as we know, are
the fundamental building blocks of nature. We’ve never discovered anything
smaller than the electron, and we’ve never discovered
anything smaller than the quarks. So we have three particles
of which everything we know is made. And it’s worth stressing,
that’s kind of astonishing. You know? We sort of take it for granted. We learn this in school. We don’t really think
about it deeply. Everything we see in the
world, all the diversity in the natural world, you,
me, everything around us, just the same three
particles with slightly different rearrangements
repeated over and over and over again. It’s an amazing lesson
to draw about how the world is put together. So that’s what we have. We have an electron
and two quarks. And you know, these aren’t the
fundamental building blocks that the Greeks
had thought about, and they’re certainly not the
fundamental building blocks that the Victorians
had thought about. But you know, the spirit of the
issue really hasn’t changed. The spirit is exactly
what Democritus said 2,500 years ago, that
they’re like LEGO bricks from which everything in
the world is constructed. These LEGO bricks are
particles, and the particles are the electron and two quarks. It’s a very nice picture. It’s a very comforting picture. It’s the picture we
teach kids at school. It’s the picture we
even teach students in undergraduate university. And there’s a problem with it. The problem is it’s a lie. It’s a white lie. It’s a white lie that
we tell our children because we don’t
want to expose them to the difficult and horrible
truth too early on it. It makes it easier to
learn if you believe that these particles are
the fundamental building blocks of the universe. But it’s simply not true. The best theories that
we have of physics do not have underlying them
the quark particle and the two quark particle– sorry, the
electron particle and the two quark particles. In fact, the very best
theories we have of physics don’t rely on particles at all. The best theories
we have tell us that the fundamental
building blocks of nature are not particles, but
something much more nebulous and abstract. The fundamental building
blocks of nature are fluid-like
substances which are spread throughout
the entire universe and ripple in strange
and interesting ways. That’s the fundamental
reality in which we live. These fluid-like substances
we have a name for. We call them fields. So this is a picture of a field. This isn’t the kind of field
that physicists have in mind. You know, this is what you think
a field is if you’re a farmer or if you’re a normal person. If you’re a physicist, you
have a very different picture in your mind when you
think about fields. And I’ll tell you the general
definition of a field, and then we’ll go
through some examples so that you get
familiar with this. The physicist’s definition
of a field is the following. It’s something that, as I
said, is spread everywhere throughout the universe. It’s something that
takes a particular value at every point in space. And what’s more, that
value can change in time. So a good picture
to have your mind is fluid, which ripples and
sways throughout the universe. Now, it’s not a new idea. It’s not an idea that
we’ve just come up with. It’s an idea which dates
back almost 200 years. And like so many other
things in science, it’s an idea which
originated in this very room. Because as I’m sure
many of you are aware, this is the home
of Michael Faraday. And Michael Faraday initiated
this lecture series in 1825. He gave over a hundred of these
Friday evening discourses, and the vast majority of these
were on his own discoveries on the experiments he did on
electricity and magnetism. So he did many, many things
in electricity and magnetism over many decades. And in doing, so he
built up an intuition for how electric and
magnetic phenomena work. And the intuition
is what we now call the electric and magnetic field. So what he envisaged was
that threaded everywhere throughout space were these
invisible objects called the electric and
magnetic fields. Now, we learned this in school. Again, it’s something
that we sort of take for granted because we
learned it at an early age, and we don’t sort of appreciate
just how big of a radical step this idea of Faraday’s is. I want to stress, it’s one
of the most revolutionary abstract ideas in the
history of science, that these electric and
magnetic fields exist. So let me just– you’re supposed to be
demonstrations in this. I’m not just a
theoretical physicist. I’m a very
theoretical physicist. It’s very hard for me to do
any kind of experiment that’s going to work. But I’m just going to show you
something that you’ve all seen. They’re magnets. OK? And we all played these
games when we were kids or when we were in school. You take these magnets,
and you move them together. And as they get
closer and closer, there’s this force that
you can sort of just feel building up that pushes,
the pressure that pushes against these two magnets. And it doesn’t matter
how often you do it, and it doesn’t matter how many
degrees you have in physics. It’s just a little bit magical. You know? And you all know this. There’s something just special
about this weird feeling that you get between magnets. And this was Faraday’s genius. It was to appreciate that even
though you can’t see anything in between, even though no
matter how closely you look, the space between these
magnets will seem to be empty, he said nonetheless, there’s
something real there. There’s something real and
physical, which is invisible, but he’s building
up, and that’s what’s responsible for the force. So he called them
lines of force. We now call it the
magnetic field. So this, of course, is a
picture of Michael Faraday. This is a picture of
Michael Faraday lecturing behind this very table. Here is a drawing from one
of Michael Faraday’s papers. It was pointed
out to me earlier. When you leave, there’s
a carpet just here. The carpet has this
pattern, this picture just repeated on it over
and over and over again. And on the bottom here is one
of Michael Faraday’s most famous demonstrations that he did here. So I’ll just walk you
through what Faraday did. The thing on the right, there’s
a small coil with a hand on it. This is a battery, and the
battery passes a current around this coil. And in doing so,
there’s a magnetic field that’s induced in this. It’s what’s called a solenoid. And then Faraday did
the following thing. He simply moved this small
coil A through this big coil B like this. And something
miraculous happened. When you do that, there’s
a moving magnetic field. Faraday’s great
discovery was induction. It gives rise to a
current in B, which then over on this
end of the table, makes a needle
flicker like this. So extremely simple. You move a magnetic
field, and it gives rise to a current, which
makes a needle flicker on the other side of the table. This astounded
audiences in the 1800s. Because you were doing something
and affecting the needle on the other end of the
table, yet you never touched the needle. It was amazing. You could make something move
without ever going near it, without ever touching it. We’re kind of jaded these days. You can do the same experiment. You can pick up your cell phone. You can press a few buttons. You can call somebody
on the other end of the earth within seconds. But it’s the same principle. But this was the first
time it was demonstrated that the field is real. You can communicate
using the field. You can affect things
far away using the field without ever touching it. So this is Michael
Faraday’s legacy. There’s not just
particles in the world. There’s other objects that
are slightly more subtle that are called fields that are
spread throughout all of space. By the way, if you ever
want to really appreciate the genius of Michael Faraday,
he gave this lecture in 1846. He gave many lectures in 1846. But there was one
in particular where he finished 20 minutes early. He ran out of
things to say, so he engaged in some idle
speculation for 20 minutes. And Faraday suggested that
these invisible, electric, and magnetic fields
that he’d postulated were quite literally the
only thing we’ve ever seen. He suggested that
it’s ripples of the electric and magnetic field,
which is what we call light. So it took a course 50 years for
people like Maxwell and Hertz to confirm that this is
indeed what light is made of, but it was Faraday’s genius
that appreciated this, that there were waves in
the electric magnetic field, and those waves are the
light that we see around us. OK. So this is Faraday’s legacy. But it turns out this idea of
fields was much more important than Faraday had realised. And it took over
150 years for us to appreciate the
importance of these fields. So what happened
in these 150 years was that there was a small
revolution in science. In the 1920s, we realised
that the world is very, very different from the
common sense ideas that Newton and Galileo had handed down
to us centuries before. So in the 1920s, people like
Heisenberg and Schrodinger realised that on
the smallest scales, on the microscopic scales, the
world is much more mysterious and counter-intuitive than we
ever really imagined it could be. This, of course, is
the theory that we now know as quantum mechanics. So there’s a lot I could
say about quantum mechanics. Let me tell you one of the
punch lines of quantum mechanics one of the punch lines is
that energy isn’t continuous. Energy in the world
is always parcelled up into some little discrete lump. That’s actually what
the word quantum means. Quantum means
discrete or a lump. So the real fun starts
when you try and take the ideas of quantum
mechanics, which say that things
should be discrete, and you try to combine them
with Faraday’s ideas of fields, which are very much continuous,
smooth objects, which are waving and
oscillating in space. So the idea of trying to combine
these two theories together is what we call
quantum field theory. And here’s the implication
of quantum field theory. The first implication
is what happens for the electric
and magnetic field. So Faraday taught us,
and Maxwell later, that waves of the
electromagnetic field are what we call light. But when you apply
quantum mechanics to this, you find that these
light waves aren’t quite as smooth and
continuous as they appeared. So if you look closely
at light waves, you’ll find that they’re
made of particles. They’re little
particles of light, and these are particles
that we call the photon. The magic of this idea is
that that same principle applies to every single other
particle in the universe. So there is spread everywhere
throughout this room something that we call the electron field. It’s like a fluid that fills
this room and, in fact, fills the entire universe. And the ripples of
this electron fluid, the ripples of the
waves of this fluid, get tied into little
bundles of energy by the rules of
quantum mechanics, and those bundles of energy
are what we call the particle, the electron. All the electrons that are in
your body are not fundamental. All the electrons that
exist in your body are waves of the same
underlying field. And we’re all connected
to each other. Just like the waves
on the ocean all belong to the same
underlying ocean, the electrons in your body
are ripples of the same field as the electrons in my body. There’s more than this. There’s also in this
room two quark fields. And the ripples of
these two quark fields give rise to what we call the
up quark and the down quark. And the same is true
for every other kind of particle in the universe. There are fields that
underlie everything. And what we think of as
particles aren’t really particles at all, they’re
waves of these fields tied up into little bundles of energy. This is the legacy of Faraday. This is where Faraday’s
vision of fields has taken us. There are no particles
in the world. The basic fundamental building
blocks of our universe are these fluid-like
substances that we call fields. All right. OK. So what I want to do in
the rest of this talk is tell you where
that vision takes us. I want to tell you about
what it means that we’re not made of particles. We’re made of fields. And I want to tell you
what we can do with that, and how we can best understand
the universe around us. OK? So here’s the first thing. Take a box and take
every single thing that exists out of that box. Take all the particles
out of the box, all the atoms out of the box. What you’re left with
is a pure vacuum. And this is what the
vacuum looks like. So what you’re looking at
here is a computer simulation using our best theory
of physics of something called the standard model,
which I’ll introduced later. But it’s a computer simulation
of absolutely nothing. This is empty space. Literally empty space
with nothing in it. This is the simplest
thing you could possibly imagine in the universe. And you can see, it’s an
interesting place to be, an empty space. It’s not dull and boring. What you’re looking at
here is that even when the particles are taken
out, the field still exists. The field is there. But what’s more, the field
is governed by the rules of quantum mechanics. And there’s a principle in
quantum mechanics, which is called the Heisenberg
Uncertainty Principle, which says you’re not
allowed to sit still. And the field has to obey this. So even when there’s
nothing else there, the field is constantly
bubbling and fluctuating in what’s, quite honestly,
a very complicated way. These are things that we call
quantum vacuum fluctuations. But this is what
nothingness looks like from the perspective of
our current theories of physics. It’s worth saying that this
is a computer simulation. It looks a little
bit like a cartoon, but it’s actually quite a
powerful computer simulation, and it took a long time to do. But these aren’t
just theoretical. These quantum fluctuations that
are there in the pure vacuum are things that we can measure. There’s something called
the Casimir force. The Casimir force is a force
between two metal plates that get pushed
together basically because there’s more of
this stuff on the outside than on the inside. And you know, these are real. These are things
that we can measure, and they behave just
as we would predict they would from our theories. So this is nothing. And this brings me to the more
mathematical side of the talk. Because there’s a
challenge in this. This is the simplest
thing we can imagine in the entire
universe, and it’s complicated. It’s astonishingly complicated. It doesn’t get easier than this. You know, if you want
to now understand not nothing but a
single particle, well, that’s much more
complicated than this. And if you want to understand
10 to the 23 particles all doing something
interesting, that’s really, really much more
complicated than this. So there’s a problem in– it’s my problem, not yours– in addressing this fundamental
description of the universe, which is that it’s just hard. The mathematics that we use
to describe quantum fields, to describe
everything that we’re made of in terms
of quantum fields, is substantially more
difficult than the maths that arises in any other
area of physics or science. It’s genuinely difficult. I can put this in
some perspective. There’s a list of six open
problems in mathematics. They’re considered
to be the six hardest problems in mathematics. There used to be seven,
but some crazy Russian guy solved one of them. So there’s six left. You win a million
bucks if you can solve any one of these problems. If you know a little
bit of mathematics, they’re things like the Riemann
hypothesis, or P versus MP. They’re sort of famously
difficult problems. This is one of
those six problems. You win a million dollars
if you can understand this. So what does it mean? It doesn’t mean can you
build a big computer and just demonstrate
that these are there. It means can you understand
from first principles by solving the equations
the patterns that emerge within these
quantum fluctuations? It’s an extraordinarily
difficult problem. You know, it’s writing
the kind of thing I do. I don’t know a single person
in the world who’s actually working on this problem. That’s how hard it is. We don’t really even
know how to begin to start understanding these
kind of ideas in quantum field theory. OK. This theme about the
mathematics being challenging is something which is going to
come back later in the talk. So I’d like just to take a
little bit of a diversion for a few minutes and give
you a sense about what we can do
mathematically and what we can’t do mathematically,
just to sort of tell you what the state of play is
in terms of understanding these theories called
quantum field theories which underlie our universe. So there are times
where we understand extremely well what’s going
on with quantum fields. And that happens basically
when these fluctuations are very calm and tame, when
they’re not wild and strong. These ones are big. But when they’re
much more calmer, when the vacuum is much
more like a mill pond than it is like a raging
storm, in those cases, we really think we
understand what we’re doing. And to illustrate this, I just
want to give you this example. So this number g is
a particular property of the electron particle. And I’ll quickly
explain what it is. The electron is a
particle, and it turns out the electron spins. It orbits rather like
the earth orbits. And it has an axis of spin. And you can change
the axis of that spin. And the way you change it
is you take a magnetic field like this. And in the presence
of a magnetic field, the electron will spin. The electron will stay
in one place, but spin. And then the axis of spin
will slowly rotate like this. It’s what’s called procession. And the speed at which the
axis of that spin processes is dictated by this number here. OK? So it’s not the most important
thing in the big picture. However, historically,
this has been extremely important in the history of
physics, because it turns out, this is a number you can
measure very, very accurately doing experiments. And so this number
has sort of acted as a testing ground for us
to see how well we understand the theories that
underlie nature, and in particular,
quantum field theory. So let me tell you what
you’re looking at here. The first number is the
result of many, many decades of painstaking experiments
measuring very, very precisely this feature of the electron. It’s called the magnetic
moment, for what it’s worth. And the second
number is the result of many, many decades of very
torturous calculations sitting down with a pen and
paper and trying to predict from first principles
from quantum field theory what the magnetic moment of
the electrons should be. And you can see, it’s
simply spectacular. And there’s nothing
like this anywhere else in science with an
agreement between the theoretical calculation and
the experimental measurements. I think it’s 12 or 13
significant figures. It’s really astonishing. Any other area of
science, you’ll be jumping up and down for
joy if you get the first two numbers right. Economics, not even that. [LAUGHING] Just that this is where
we’re at in particle physics on a good day when
we really understand what we’re doing with it. It’s substantially better than
any other area of science. 12 significant figures. But this, of course,
I’ve shown you because this is our
best result. There are many other results that
are nowhere near as good. And the difficulty comes
when those quantum vacuum fluctuations start getting
wilder and stronger. So let me give you an example. It should be possible for
us to sit down and calculate from first principles
the mass of the proton. We have the equations. Everything should be there. We just need to work
hard and figure out what the mass of the proton
is just by doing calculations. We’ve been trying to do
this for about 40 years now. We can get it to within an
accuracy of something like 3%. Which isn’t bad. We’re 3% there. But we should be
much, much better. We should be sort of pushing
these levels of accuracy. And the reason is very simple. We’ve got the right equation. We’re pretty sure we’re
solving the right equation. It’s simply that we’re not
smart enough to solve it. In 40 years, the world’s
most powerful computers, lots and lots of smart people. But we haven’t managed
to figure this out. OK. There are other
situations that I won’t tell you about where we
don’t even get off the ground. There are some situations
where for fairly subtle reasons we’re unable to use
computers to help us, and we simply have no
idea what we’re doing. So it’s a slightly
strange situation. We have these
theories of physics. They’re the best theories
we’ve ever developed, as you can see by this. But at the same time,
they’re also the theories that we understand
the least and it’s to make progress we sort of
have this strange balancing act between increasing our
theoretical understanding and figuring out how to
apply that to the experiments that we’re doing. And again, it’s a
theme I’ll come back to at the end of the lecture. All right. So so far, I’ve been talking
in a little bit of generality about what we’re made of. And this is the punch line for
the halfway point of the talk. You’re all made
of quantum fields, and I don’t understand them. At least I don’t understand them
as well as I think I should. So what I want to do now
is go into a little bit more specifics. I want to tell you exactly what
quantum fields are made of. In fact, I’ll tell you
exactly what quantum fields exist in the universe. And the good news
is, not many of them. So I’ll simply tell
you, all of them. So we started with
the periodic table. This is the new periodic table. And it’s much simpler. You know, it’s much nicer. There are the three particles
that we’re all made of. There’s the electron
and the two quarks, the up quark and the down quark. And as I’ve stressed, the
particles aren’t fundamental. What’s really fundamental is
the field that underlies them. And then it turns out
there’s a fourth particle that I’ve not discussed so far. It’s called the neutrino. It’s not important in
what we’re are made of, but it does play another
important role elsewhere in the universe. These neutrinos are everywhere. You’ve never noticed them,
but since I began this talk, something like 10
to the 14 of them have streamed through the body
of each and every one of you, as many coming from
above from outer space as actually coming from
below, because they stream all the way through
the earth and then keep going. They’re not very sociable. They don’t interact. So this is what
everything is made of. These are the four
particles that form the bedrock of our universe. Except then something
rather strange happened. For a reason that we do
not understand at all, nature has chosen to
take these four particles and reproduce them twice over. So this is actually the
list of all the fields that make up particles
in our universe. So what are we looking at here? This is the electron. It turns out there are
two other particles which behave in every way exactly
the same as the electron, except they’re heavier. We call them the muon which
has a mass of something like 200 times the electron,
and the tau particle, which is 3,000 times
heavier than the electron. Why are they there? We have no idea at all. It’s one of the mysteries
of the universe. There’s also two more neutrinos. So there are three
neutrinos in total. And the two quarks that we
first knew about are now are joined by four others
that we call the strange quark and the charmed quark. And then by the
time we got here, we really ran out of any kind
of inspiration for naming them. We called them the bottom
quark and the top quark. So I should stress. We understand things very,
very well going this way. We understand why they
come in a group of four. We understand why they have
the properties that they do. We don’t understand it
at all going this way. We don’t know why
there’s three of these rather than two of
them or 17 of them. That’s a mystery. But this is everything. This is everything
in the universe. Everything you’re made of is
these three at the top there. And it’s only when you go
to more exotic situations, like particle colliders, that we
need the others on the bottom. But every single
thing we’ve ever seen can be made out of these
12 particles, 12 fields. These 12 fields interact
with each other, and they interact through
four different forces. Two of these are
extremely familiar. They’re the force of gravity and
the force of electromagnetism. But there’s also two other
forces which operate only on small scales of a nucleus. So there’s something called
the strong nuclear force, which holds the quarks together
inside protons and neutrons. And there’s something called
the weak nuclear force, which is responsible for radioactive
decay and among other things, for making the sun shine. Again, each of these forces
is associated to a field. So Faraday taught us about
the electromagnetic field, but there’s a field
associated to this, which is called the gluon
field and a field associated to this which is called
the W and Z boson field. There’s also a field
associated to gravity. And this was really Einstein’s
great insight into the world. The field associated
to gravity turns out to be space and time itself. So if you’ve never
heard that before, that was the world’s
shortest introduction to general relativity. And I’m not going to say
anything else about it. I’ll just let you figure
that one out for yourself. OK. So this is the
universe we live in. There are 12 fields
that give matter, I’ll call the matter field,
and four other fields that are the forces. And the world we live
in is these combination of the 16 fields all interacting
together in interesting ways. So this is what you should
think the universe is like. It’s filled with these
fields, fluid-like substances. 12 matter, four forces. One of the matter fields
starts to oscillate and ripple. Say the electron field
starts to wave up and down, because there’s electrons there. That will kick off one
of the other fields. It’ll kickoff, say, the
electromagnetic field, which, in turn, will also
oscillate and ripple. There’ll be light
which is emitted. So that will oscillate a little. At some point, it
will start interacting with the quark field, which in
turn will oscillate and ripple. And the picture we end up
with is this harmonious dance between all these fields,
interlocking each other, swaying, moving this
way and that way. That’s the picture that we
have of the fundamental laws of physics. We have a theory which
underlies all this. It is, to put it simply,
the pinnacle of science. It’s the greatest theory
we’ve ever come up with. We’ve given it the most
astonishingly rubbish name you’ve ever heard of. We call it the standard model. When you hear the name
the standard model, it sounds tedious and mundane. It should really be replaced
by The Greatest Theory in the History of
Human Civilisation. OK? That’s what we’re looking at. OK. So this is everything,
except it’s not quite. I’ve actually just
missed that one field. There’s one extra
thing we know about, which became quite
famous in recent years. It was a field that was
first suggested in the 1960s by a Scottish physicist
called Peter Higgs. And by the 1970s, it had become
an integral part of the way we thought about the universe. But for the longest
time, we didn’t have direct
experimental evidence that this existed, where direct
experimental evidence means we make this Higgs Field ripple
so we see a particle that’s associated to it. And this changed. This changed famously
four years ago at the LHC. These are the two experiments
of the LHC that discovered it. They’re sort of the
size of cathedrals, and just packed
full of electronics. They’re astonishing things. This is called Atlas. This is called CMS. That Higgs particle
doesn’t last for long. The Higgs particle lasts about
10 to the minus 22 seconds. So it’s not like you see it and
you get to take a picture of it and put it on Instagram. It’s a little more subtle. So this is the data, and
this little bump here is how we know that this
Higgs particle existed. This is a picture of
Peter Higgs being found. So this was the
final building block. You know, it was important. It was a really big deal. And it was important
for two reasons. The first is that this is
what’s responsible for what we call mass in the universe. So the properties of
all the particles, things like electric
charge and mass, are really a statement about
how their fields interact with other fields. So the property that we call
electric charge of an electron is a statement about how
the electron field interacts with the electromagnetic field. And the property of its
mass is the statement about how it interacts
with the Higgs field. So understanding this
was really needed so that we understand
the meaning of mass in the universe. So it was a big deal. The other reason that
it was a big deal is, this was the final
piece of our jigsaws. We had this theory that we
called the standard model. We’ve had it since the 1970s. This was the final
thing that we needed to discover to be sure that
this theory is correct. And the astonishing
thing is this particle was predicted in the 1960s. 50 years we’ve been waiting. We finally created it in CERN. It behaves in exactly the
way that we thought it would. Absolutely perfectly
behaves as we predicted using these theories. OK. This is going to be the
scary part of the talk. I’ve been telling you
about this theory. And I’ve been waving my hands
pretending that I’m a field. Let me tell you what
the theory really is. Let me just show you what we do. This is the equation for the
standard model of physics. I don’t expect you to
understand it, not least because there are parts of
this equation that no one on the planet understands. But nonetheless, I
want to show it to you for the following reason. This equation correctly
predicts the result of every single experiment
we’ve ever done in science. Everything is contained
in this equation. This is really the pinnacle
of the reductionist approach to science. It’s all in here. So I’ll admit. It’s not the simplest
equation in the world. But it’s not the most
complicated either. You can put it on a
t-shirt if you want. In fact, if you go to
CERN, you can buy a t-shirt with this equation on it. Let me just give you a sense
of what we’re looking at. The first term here was
written down by Albert Einstein and describes gravity. What that means is
that if you could solve this tiny little part of
the equation, just this R, you can, for example, predict
how fast an apple falls from a tree, or the fact
that the orbits of the planet around the sun form ellipses. Or you can predict what happens
when two enormous black holes collide into each other
and form a new black hole, sending out gravitational
waves across the universe. Or in fact, you can predict
how the entire universe itself expands . All of this comes from
solving this little part of the equation. The next term in the
equation was written down by James Clerk Maxwell,
and it tells you everything about electromagnetism. So all the experiments that
Faraday spent a lifetime doing in this building– in fact,
all the experiments over many centuries, from
Coulomb to Faraday, to Hertz to modern developments
of lasers, everything– in this tiny little
part of the equation. So there’s some power
in these equations. This is the equation
that governs the strong nuclear force,
the weak nuclear force. This is an equation
that was first written down by a British
physicist called Paul Dirac. It describes the matter. It describes those 12 particles
that make up the matter. Astonishingly,
each of them obeys exactly the same equation. These are the equations
of Peter Higgs. And this is an
equation that tells you how the matter interacts
with the Higgs particle. So everything is in here. It’s really an
astonishing achievement this is our current
limit of knowledge. We’ve never done an experiment
that cannot be explained by this equation. And we’ve never
found a way in which this equation stops working. So this is the best thing
that we currently have. OK. It’s the best thing
that we currently have. However, we want to
do better, because we know for sure that
there’s stuff out there that is not explained by this. And the reason we know is
that although this explains every single experiment we’ve
ever done here on Earth, if we look out into the sky,
there’s extra stuff which is still a mystery. So if we look out into space,
there are, for example, invisible particles out there. In fact, there’s many
more invisible particles than there are
visible particles. We call them dark matter. We can’t see them, obviously,
because they’re invisible. But we can see their effects. We can see their effects
in the way galaxies rotate, or the way they
bend light around galaxies. They’re out there. We don’t know what they are. There’s even more
mysterious things. There’s something called
dark energy, which is spread throughout all of space. It’s also some kind of field,
although not one we understand, that’s causing everything
in the universe to repel everything else. Other things. We know that early in
the first few seconds, earlier than that, the
first few fractions of a second after the
Big Bang, the universe underwent a very rapid
phase of expansion that we call inflation. We know it happened, but it’s
not explained by that equation that I just showed you. So these are the kind
of things that we’re going to have to
understand if we’re going to move forward and decide
what the next laws of physics are that go beyond
the standard model. I could spend hours
talking about any of these. I’m going to focus
just on the last one. I’m going to tell you a
little bit about inflation. So the universe is
13.8 billion years old. And we understand
fairly well– well, we don’t understand
at all how it started. We don’t understand what kicked
it all off at time t equals 0. But we understand fairly well
what happened after it started. And we know in particular
that for the first 380,000 years of the universe, it
was filled with a fireball. And we know this for
sure because we’ve seen the fireball. In fact, we’ve seen it, and
we’ve taken a photograph of it. This is called the cosmic
microwave background radiation, but a much better name
for it is the Fireball That Filled the Universe
When It Was Much Younger. The fireball cools down. It’s light has been streaming
through the universe for 13.8 billion years. But we can see it. We can take this
photograph of it. And we can understand
very well what was happening in these first
few moments of the universe. And you can see, it looks
literally like a fireball. There’s red bits
that are hotter. There’s blue bits
that are colder. And by studying this
flickering that you can see in this picture,
we get a lot of information about what was going on back
13.8 billion years ago when the universe was a baby. One of the main
questions we want to ask is what caused the
flickering in the fireball? And we have an answer to this. We have an answer,
which I think is one of the most astonishing
things in all of science. It turns out that
although the fireball lasted for 380,000
years, whatever caused this flickering
could not have taken place during the vast
majority of that time. Whatever caused the
flickering in this fireball actually took place in the first
few very fractions of a second after the Big Bang. And what it was
was the following. So when the universe
was very, very young, soon after the Big Bang,
there were no particles, but there were quantum
fields, because the quantum fields were everywhere. And there were these
quantum vacuum fluctuations. And what happened was the
universe expanded very, very quickly, and it caught
these quantum fluctuations in the act. So the quantum
fluctuations were stretched across the entire sky,
where they became frozen. And it’s these vacuum
fluctuations here which are the ripples that
you see in the fireball. So it’s an astonishing story,
that the quantum vacuum fluctuations were taking place
10 to the minus 30 seconds after the Big Bang. They were absolutely
microscopic. And now we see them stretched
across the entire universe, stretched 20 billion
lightyears across the sky. That’s what you’re seeing here. And yet, you do the
calculations for this, and it matches perfectly
what you see here. So this is another of the
great triumphs of quantum field theory. But it leaves lots of questions. The most important one is,
which field are we seeing here? Which field is this that’s
imprinted on the background radiation? And the answer is we don’t know. The only one of
the standard model fields it has a hope
of being is the Higgs. But most of us think
it’s not the Higgs, but probably something new. But what we’d like to do
moving forward into the future is get a much better
picture of this fireball, in particular get the
polarisation of the light. And by getting a
picture of this, we can understand much
better the properties of this field that
was fluctuating in the early universe. OK. This looking forward is
one of the best hopes that we have for going
beyond the standard model and understanding new physics. In the last 10
minutes, though, I’d like to bring you back
down to Earth, sort of. We’ve got lots of
experiments here on Earth where we’re also
trying to do better, where we’re also trying to
go beyond the standard model of physics beyond that equation
to understand what’s new. And there’s many of them,
but the most prominent is the one I’ve
already mentioned. It’s the LHC. So what happened was the LHC
discovered the Higgs boson in 2012. And soon afterwards, it
closed down for two years. It had an upgrade. And last year in 2015,
the LHC turned on again with twice the
energy that it had when it discovered the Higgs. And the goal was twofold. The goal was firstly to
understand the Higgs better, which it has done fantastically,
and secondly, to discover new physics that lies beyond
the Higgs, new physics beyond the standard model. So before I tell
you what it’s seen, let me tell you some
of the ideas we’ve had, some of our expectations
and hopes for what would happen moving forward. So this is our favourite
equation again. The idea has always
been the following. You know, if you were
a Victorian scientist, and you go back, and you look at
the periodic table of elements, then it’s true that there’s
patterns in there that give a hint of the structure
that lies underneath. Those numbers that
repeat themselves. Where if you’re very smart, you
might start to realise that, yes, there is something deeper
than just these elements. So our hope as theorists
is to look at this equation and see if maybe we
can just find patterns in this equation that suggest
there might be something deeper that lies underneath. And they’re there. So let me give you an example. This is the equation
that describes the force of electricity and magnetism. And it’s almost the same
as the equations which describe the forces
for the strong force and the weak nuclear force. You can see. I’ve just changed letters. It’s a little more
complicated than that, but it’s not much more
complicated than that. The three forces
really look similar. So you might wonder,
well, maybe there’s not three forces in the universe. Maybe those three forces
are actually just one force. And when we think
there’s three forces, it’s because we’re
looking at that one force just from slightly
different perspectives. Maybe. Here’s something else,
which is amazing. These are the equations
for the 12 matter fields in the universe– the
neutrinos, the electrons, and the quarks. Each of them obeys
exactly the same equation. Each of them obeys
the Dirac equation. So again, you
might wonder, well, maybe there aren’t
12 different fields. Maybe they’re all the same
field and the same particle, and the fact they look
different is, again, maybe just because
at them from slightly different perspectives. Maybe. So these ideas that
I’ve been suggesting go by the name of unification. The idea that the three forces
are actually combined into one is what’s called
grand unification. And it’s very easy. It’s very easy to write down
a mathematical theory in which all of these are just one
force, which appears to be three from our perspective. There are other
possibilities here. You might say, well
this is the matter, and these are the forces. And the equations are different,
but they’re not that different. Because ultimately,
they’re both just fields. So you might wonder
if maybe there’s some way in which the
matter and the forces are related to each other. Well, we have a theory
for that as well. It’s a theory that’s
called supersymmetry. And it’s a beautiful theory. It’s very deep conceptually. And it sort of, you know,
smells like it might be right. Finally, you might be
really, really bold. You might say, well, can
I just combine the lot? Can I just get rid
of all of these terms and just write down
one single term from which everything
else emerges? Gravity, the forces, the
particles, the Higgs, everything. I’ve got something for you
if you want that as well. It’s called string theory. So we have a possibility for
a theory which contains all of this in one simple concept. And the question going forward,
of course, is are these right? You know, it’s very easy for us
theorists to have these ideas. And I should say
these ideas are what’s driven theoretical physics for
30 years, but we want to know, are they right? And we’ve got a way of
telling they’re right. We do experiments. So I should say, if you want to
know if string theory’s right, we don’t have any way to
test it at the moment. But if you want to know if some
of these other ideas are right, then that’s what the
LHC should be doing. The reason that we built the LHC
was firstly to find the Higgs. OK, it worked, and secondly,
to test these kind of ideas that we’ve been having
to see what lies beyond. So the LHC has been running. It’s been running for two years. It’s been running like
an absolute dream. It’s a perfect machine. Two years. This is what it’s seen. Absolutely nothing. All of these fantastic
beautiful ideas that we’ve had, none of them are
showing up at all. And the question going
forward is, what are we going to do about it? How are we going
to make progress in understanding the
next layer of physics when the LHC isn’t
seeing anything, and our ideas just don’t appear
to be the way that nature works? I should tell you, often I don’t
have a good answer to this. My impression is that
most of my community is a little bit shell-shocked
by what happened. There’s certainly no
consensus in the community to move forward. But I think there’s
three responses that sort of various
people have had that I’d like to share with you. And I think all three
of these responses are reasonable up to a point. The first response to the
LHC not seeing anything is the following. You young kids,
you’re so pessimistic. It’s all doom and
gloom with you. You need a little
bit more patience. You know, I didn’t see
anything last year, and I didn’t see
anything this year. But next year, it’s
going to see something. And if not next year,
it’s the year after that that it’s going
to see something. It’s usually my very
illustrious senior colleagues that have this– and you know what? They could easily be right. It could easily be that
next year, the LHC discovers something astonishing,
and it sets us on the path to understanding
the next layer of reality. But it’s also true
that these same people were predicting that it would
have seen something by now. And it’s also true
that this can’t keep going for much longer. If the LHC doesn’t see something
within, say, a two-year time scale, it seems
very, very unlikely that it’s going to see
something moving forward. It’s possible. It just seems unlikely. So I hope with all my heart
that the LHC discover something next year or the year after. But I think we have to
prepare for the worst, that maybe it won’t. OK. Response number two. Response number two, which is
sort of also by similar people, well, all our theories
are so beautiful. They absolutely
have to be correct, and what we really need
is a bigger machine. 10 times bigger will do it. Again, they might be right. I don’t have a good
argument against it. The obvious rebuttal,
however, is that a new machine cost $10 billion. There’s not too many
governments in the world that have $10 billion to spare
for us to explore these ideas. There’s one. The one is China. And so if this machine is
going to be built at all, it’s going to be built by
the Chinese government. I think the Chinese government
would see it as extremely attractive if the whole
community of particle physicists and engineers
that are currently based in CERN and Geneva
move to a town that’s slightly north of Beijing. I think they’d view that as
political and economic gain, and there’s a real
chance they may decide to build this machine. If they do, it’s about 20
years for it to be built. So we’re waiting
slightly longer. There’s a third response. And I should say
the third response is kind of the camp I’m in. I should mention upfront,
it’s speculative , and it’s probably not
endorsed by most of my peers. So this is really just my
personal opinion at this point. This is my take on this. This is the equation
that we know is right. This is sort of the bedrock
of our understanding. But although we know
it’s right, there’s an awful lot in this equation
that we haven’t understood. There’s an awful lot
to me that’s still mysterious in this equation. So although this equation
looked like there were suggestions of
unification, maybe they’re just red herrings. And maybe if we just
work harder in trying to understand this
equation more, we’ll find that there are
other patterns that emerge. So my response is, I think
that maybe we should just go back to the drawing
board and start to challenge some of the
assumptions and paradigms that we’ve been holding
for the past 30 years. So I feel quite
energised, actually, by the lack of
results for the LHC. You know? Sort of it feels good to
me that everyone was wrong. You know, it’s when we’re wrong
that we start to make progress. So I sort of feel
quite happy about this, and think that there’s a very
real chance that we could just start thinking about
different ideas. I should say that there
are hints in here. There are hints to me
about mathematical patterns that we haven’t explored. There’s hints in this
about connections to other areas of science. Things like condensed
matter physics, which is the science
of how materials work, or quantum information
science, which is the attempt to build a quantum computer. All these fantastic
subjects have new ideas, which sort of feed in
to the kind of questions that we’re asking here. So I’m quite optimistic
that moving forward, we can make progress,
maybe not the progress that we thought we’d make a few
years ago, but just something new. So that’s the
punchline of my talk. The punchline is that this is
the single greatest equation that we’ve ever written down. But I hope that someday, we
can give you something better. Thank you for your attention. [APPLAUSE] There’s nothing discrete about
the Schrodinger equation. The Schrodinger
equation is something to do with a smooth
field-like wave function. The discreteness
is something which emerges when you solve
the Schrodinger equation. So it’s not built into
the heart of nature.

Dereck Turner

100 thoughts on “Quantum Fields: The Real Building Blocks of the Universe – with David Tong

  1. Mohammed Batir says:

    Can we beam energy at a field, maybe using lasers, to a point in space and give rise to an electron or other fundamenral particles?

    If so, can we theoretically beam an object into existance?

  2. قرأت لك says:

    I am a Muslim and we have in Quran many verses that talk about the creator of the universe as the light of earth and heavens. How can we link what you are saying with such quranic verses???

  3. Daniel Dorsz says:

    Where can I find the explanation step by step on this equation shown (theory of everything so far) ? I would love to know exactly what each symbol means to understand it. Anyone ?


    WHY AM I WRONG WHEN I SAY………There are not 12 fermion fields but only 4. The electron field….the neutrino field and the up and down quark fields. And the higher generation fields are not fields. What if i said the muon and tal does not have there own field and they are just higher energy electrons IN THE ELECTRON FIELD. What if i said a muon is just a higher energy vibration in the electron field. And a tal is just an even higher energy vibration in the electron field. If the electron is just a vibration in the electron field with enough energy to act as a particle(i will call a QUANTUM of energy from now on). And when the electron forms it is stable and it is not enough energy to interact with the EM field to form photons and so it remains an electron. So the electron field can handle the first quantum amount of energy to form the 1st genration electron particle. But if you add the next quantum amount of energy needed to the electron field then you would form a muon. And add another quantum of energy needed to form the next bigger particle called the tal. The electron field cannot sustain the higher energy to keep the muon or tal particle (vibrating) because this higher energy vibration in the electron field (which forms the muon) is high enough to hit the EM field and transfer energy to the EM field forming 2 photons and now the electron field (muon) is not vibrating as much and no longer reacts with the EM field and is now an electron instead of a muon. The mass lost from the muon when it turned into an electron is just transfered in to energy……..energy that made the photons. SO an electron is just a vibration in the electron field that has enough energy to act as a particle called an electron. If you vibrate the electron even more then the vibration acts like a particle called a muon. But the HIGHER vibrations in the electron field to make a muon interacts with the EM field to lower the vibration in the electron field to make the muon in to an electron and the muon made the EM field vibrate making 2 photons and i am just repeating myself so……….WHY AM I WRONG????????????????????????????????????????????????/ I doubt i am right but if i was that would mean that if you added enough more energy to the electron field than is needed to make a tal then there should be a 4th generation of electron particle and a 5th etc……..
    This would explain why there are 2nd and 3rd generation fermion quantum fields………the reason is that there are no 2nd and 3rd generation fields. And that all 2nd and 3rd generation particles are just higher energy vibrations in the corresponding 1st generation field. SO there is no top quark field. A top quark is just a higher energy vibration in the up quark field. Enough more energy to form a top quark instead of just an up quark AND ECT…….ETC ETC ECT ECT ……………………………………..WHY AM I WRONG ???????? WHAT I AM SAYING MAKES SO MORE SENSE. OF COURSE QUANTUM PHYSICS I GUESS SHOULD NEVER BE INSTINCTIVE I GUESS.


    YOU WOULD think that at least one physicist would answer one of my questions just for fun. With a real answer and not saying "because thats just how it is"……………

  6. DingbatToast says:

    This guy is brilliant! An engaging and charismatic presenter who doesn't need things that go bang to completely envelop and interest you in his world.
    Thank you for this gem of a lecture

  7. Lyles Fredidog says:

    There was no big bang of creation. The second quantum correction in the Friedmann equation gets rid of the big-bang singularity. In otherwords, what's here has always been here, just in a different form.

  8. HEARTIST 25 says:

    Wow straight away off the bat ignoring what the great ancient Greeks said about atoms. Yeah….better not mention any great neo-platonic logic that teach you to think with retroduction reasoning which produced some of the greatest minds that ever lived.

    Mother nature is simplex. 'modern' physics and quantum science is a cult of bumping particle fantasies. It's a bunch of boring mental midget, egotistical, atomistic, brain dead bean counting left brained morons trying to understand the nature of reality, getting lost in meaningless equations that have no basis on reality while leaving out electrical engineering, magnetism and metaphysics. All i had to do is watch 2 seconds of this before i nearly vomited in my mouth. I hope it goes and dies in a hole soon. Just like the good for nothing Einstein's theories should have. Just excuse me for a second….i have to go and empty out some built up photon particles from the back of my camera lens.

  9. Henryk Gödel says:

    Can you guys do a lecture on consciousness? Almost everything I find on youtube concerning the subject is woo-woo.

  10. ProfRaccoon says:

    Maxwell's theory has been proved by experiment to be wrong already on the classical level: the Coulomb near field is much faster than 'c' (measured numerous time). Jefimenko's most general field solutions of Maxwell's equation predict that all fields propagate with velocity 'c' at most, and this has been FALSIFIED BY EXPERIMENT. This experimental falsification destroys the so called "gauge symmetry" already on the level of classical fields, and it falsifies "special" relativity theory (it is 'special' because it has been incorrect all the time), that was not saint Einstein's theory anyway. A kid with a good quality oscilloscope can verifiy the superluminal nature of the Coulomb field by means of high voltage discharge experiments.

    Well, Cambridge, keep ignoring the data that falsifies your precious "master equation", it only makes your physics model more dead than it already is. If "you know the equation is right" then you are naive or you are lying. David Tong is one of many 'politically correct' THEORETICAL physicist, who are out of touch with the experimental reality of beautiful nature, and its endless possibilities. No matter how much "prices" these politically correct physicist give each other, it is more fake information, and for a pitch dark reason. I don't take "good Jewish science" for granted anymore (the phrase 'good Jewish science' was used by Einstein's friend Max Born in one of his many letters to Einstein). Our future will be way beyond this so called "correct equation", period.

  11. iamchillydogg says:

    It's all gone Dave Tong.

  12. vaibhav srivastava says:

    Awesome lecture. 🙂 🙂

    Thanks for uploading such a great lecture.

  13. bobo jepeny says:

    Too much bs….boorriinngg

  14. Samuel Tetteh says:

    excellent presentation

  15. Daniel Hedrick says:

    David tennant…I mean Tong makes a lot of good points

  16. matt b says:

    The fact that particles don’t exist and that everything is about fields is correct. The rest of the rubbish being out out by this guy and his brainwashed colleagues is ridiculous.
    It’s called intelligent design existing outside of time and space….aka, GOD!

  17. The Royal Institution says:

    Thanks to our community, we now have Galician subtitles for this video!

  18. Sammy Joe says:

    So, this guy boils everything he knows about quantum fields into a 1 hour presentation and 21 thousand people give a thumbs up. It's like giving a bite of baby food to a baby. We are all (including myself) far too stupid to even begin to grasp what is beyond the jar. As he says in the video, "They told me not to show you any equations". I feel your frustration David, but also appreciate the very small bite.

  19. Mustafa Çubukçu says:

    Thanks for lecture

  20. Oleg Kuznetsov says:

    there are discussions to build a new Linear collider which would shoot not hadrons while lighter particles and this would hopefully give times better precision of experiments. Also – the theme of mass and Higgs bozon was touched very quickly and almost nothing was said that how this manages to resolve the problems in super-symmetry model. As I understood without Higgs field all other particles were "prohibited" to have any mass… I like the idea that World is built of fields (for me this is similar to be built from energy if I am not mistaken…) . While the concept of field is till now looking like a postulate and nobody as I can see has managed to make a simple description of what is the "nature" of any field. Each concept which is used in modern physics is still too far from being well "philosophically" grounded – one thing is to create the "ideal equation" which is a good practical tool to measure the nature with high precision. Another is to make statement that this equation "describes" everything in Nature. Too heavy statement – given the fact that currently science is in general suffering from being "torn apart" with huge controversies and confusions.

  21. Humanunnaki says:

    So QFT is wrong, got it.

  22. Humanunnaki says:

    How come everyone so excited about this lecture doesn't acknowledge that at the end he basically says it's all almost certainly wrong? He's explaining it to you then telling you it's wrong and you seem to have glossed over that last, critical point.

  23. Humanunnaki says:

    His explanation of the CMB is also garbage, and the equation that predicts every experimental result ever, well that's backwards. It didn't predict anything, it was written based on results.

  24. Humanunnaki says:

    Good God, that is NOT Grand Unified Theory.

  25. Humanunnaki says:

    I do agree we should go back to the drawing board. What happened to the scientific method, scientists? Fuck it, I think I'm right, let me mislead everyone? Sweet, thanks.

  26. Maxim Dabster says:

    This was an amazing video!

  27. David Wilkie says:

    Particles, the dominant components of dimensionality, have reciprocal positioning fields of "navigational" quantization of e-Pi-i resonance imaging assemblies in hierarchical structure of AM-FM QM-TIMESPACE holographic coordination.

  28. ulhurusurf club says:

    gday..i get it..the universe is a giant toroidal field..like a wallowing doughnut the size of a universe..but made of MAGNETO-ELECTRIC ENERGY / VIBRATIONS..seems common sense to me..

  29. ulhurusurf club says:


  30. ulhurusurf club says:

    gday seems we are all just magneto-electric vibrations..PRETENDING WE ARE THE REAL ONE…NOT THE CLONE..like all the others..

  31. Etimespace says:

    One month ago between Sun and Jupiter.

    Now between Sun and Saturn.

    All that time between Sun and galaxy centre supermassive concentration.

    Lot of small area collides inside expanding Earth.

    Nucleus of atoms expanding and recycling expanding pushing force with all other expanding nucleus of atoms. That expanding pushing force have example nature of expanding light.

    Expanding light moving faster and faster same way what matter and light expanding.

    Expanding galaxys born inside to outside.


  32. Mike H says:

    this gentleman was very easy to listen to. great video.

  33. Kevin Kilpatrick says:

    36:12 wow "this is the universe we live in…" … then he sums it up quite succinctly!

  34. Kevin Kilpatrick says:


  35. lohphat says:

    3:42 120 elements?

  36. lohphat says:

    7:16 The protons and neutrons actually contain a soup of many quarks, it’s just that the three “valence quarks” determine the resulting characteristics.

  37. Ian says:

    This is a philosophy called atomism. It is the same as the as the "turtles all the way down" cosmology.

  38. isleofyew1 says:

    Invest the ten bilion dollars fast but keep looking back at the drawing board too.

  39. Louis-Philippe Thouin says:

    Great lecture! The content is profound, yet the delivery is my best experience yet of clear explanations. Much appreciated!

  40. Mgtow Values says:

    Does anyone else see a critical problem?
    At 20:17 "all electrons are waves of the same underlying field"; "…two quark fields"; "…and the same is true of every other kind of particle in the universe". "There are no particles in the world. The basic fundamental building blocks of our universe are these fluid-like substances we call fields." Okay, all particles are actually fields. At 21:54, "Take a box and take everying that exists out of that box. Take all the particles out of that box, all the atoms. What you are left with is a vacuum. {visual} What you are looking at is that even when the particles are taken out, the field still exists. The field is there."

    Does anyone else see the problem? First, fields are particles thus removing particles means removing fields. Then secondly, we have introduced a term "the field", which is singular with a definite article "the", indicating that the listener and the speaker both can point to that field. As this "the field" has not yet been defined, I a listener cannot identify (point to) "the field", though certainly given the talk so far, I can identify all particles as fields.

    At 9:44, "…the fundamental building blocks of nature are not particles… but fluid like substances … called fields". 12:04 Faraday developed the electro-magnetic field to explain how "electric and magnetic phenomena work". "Threaded everywhere throughout space were these invisible objects called the electro-magnetic field." At 12:37, "That these electric and magnetic fields exist". I am not certain from this talk what "the field", whether there are one or many electric/magnetic fields, what invisible objects are, how objects cannot be particles that then are fields and thus would be removed in the vacuum. Nice speaker, but, on many important issues, I am afraid I have been given little information with which to construct a coherent model. I had read elsewhere not only that are all particles fields, but also that all fields are particles; thus, in a quantum vacuum, there would be no field as that would imply that there is a particle. If Prof Tong believes this to be the case, then the talk is hopelessly self-contradictory.

  41. bunnihilator says:

    Perfect. Thank you for REAL information. Really great work.

  42. Saeed Hareb says:

    When you say time started to exist! WoW – that is a mouthful to digest! Based on what scale?

  43. Vladislav Gorshkov says:

    Never seen such straightforward explanation on such complex topic. 998 people must be anime lovers or deaf

  44. Mr Darren says:

    so he wears a kabbalah bracelet. a scientist occultist it seems. i wonder which evil spirits he is trying to ward off?

  45. Zoltán Kürti says:

    This is a shame. This guy butchered spin and the g factor. Really shameful.

  46. Luke A says:

    He rips the periodic table a little hard doesn't he 😅

  47. Jessica Sudoviski says:

    love it! this quantum physics subject is the best.

  48. nguttam1982 says:

    A great speech!!
    I have one question though- does the quantum field theory explain 'the measurement problem' of the double slit experiment and the delayed choice eraser experiment future influencing the past observation?

  49. Braden Lockwood says:

    If you're interested in expanding your consciousness I highly recommend checking out PyramidRealm.com. Tons of great content compiled in one site and very well organized. The website covers everything from extraterrestrial life, ancient civilizations, quantum physics, human spirituality, government conspiracies, to the dawn of a new age for civilization. The day has come for humanity to awaken to our full potential and embrace a Utopian vision for the science fiction future we all hope to witness.

  50. Richard Deese says:

    Thank you for a wonderful talk! As for the LHC not seeing anything new, I'm fully of the opinion (and I know it's only my opinion!) that there's simply nothing else to see, unless we built a machine the size of the universe! We really should go back to the drawing board, & look for symmetries & patterns – both in the math, and in the conceptual realm. I feel there's something more fundamental we're missing, some way of jiggling the same puzzle pieces in the same box until we get a new shape. Time will (hopefully) tell. Thank you again for a great job & a very enjoyable time! Rikki Tikki.

  51. Ashley says:

    During an experience with psilocybin I became aware of the magnetic field we exist in. I was in the forest and the time and space between my physical being and the physical beings of all the trees and plants and animals around me existed so fluidly, its hard to explain.

  52. mkfaruki says:

    David Tong sounds like he is a Xhosa speaker from South Africa. David clicks his way through the lecture. Xhosa uses these clicks like !david "click" david. David mispronounces "to" as "ta" mispronounces "drawing" as "drawring" According to David everyone else is wrong only he is right, the Periodic Table is wrong, the Quark Table is wrong. This sort of arrogance, completely lacking in humility, is the hallmark of a quack. Real Theoretical Physicists have humility, don't go around bashing their colleagues. Mocking chemists too. Real Theoretical Physicists don't impose their unproven ideas as fact, real theoretical physicists present all the theories on the subject and let the student decide for themselves, ask them why they decided that particular theory is correct, present them with the counter argument and listen to the student's analysis. Dreadful.

  53. Jaime Torres says:

    The density of an electromagnetic force is what we call mass ?

  54. Emmett Brown says:

    The moment he said String Theory is the moment I stopped taking it seriously 😀

  55. Eric keogh says:


  56. HappyHippy says:

    @44:49 around that time, is there heat accounted for in the equation ? Heat causes expansion

  57. John Gomes says:

    One of the best (simple and elegant) lecture on quantum fields!

  58. Derek Godzisz says:

    At 30:47 anyone happen to know any of these "situations"?

  59. vHelixv says:

    They just can’t bring themselves to say “aether”. If the aether really had “wind” it would be measurable with quantum entangled particles.
    But let’s all struggle to understand and shoehorn “quantum” when we first failed to understand “aether”.

  60. jerlands says:

    is it possible the electron is an artifact in the relationship between the proton and neutron?

  61. jerlands says:

    @21:25 this reminds me of a lava lamp 🙂 almost like an interplay in fluid duality 🙂

  62. H3ntairican says:

    In order for nothing to be nothing it has to be something☺

  63. Official Voxik says:

    Has anyone considered the quantum vacuum fluctuations are the node point cross section of higher dimensional objects/fields moving through our dimension? The movement looks similar to the way higher dimensional objects move

  64. Zion Kim says:

    He was one of my two interviewers at my Cambridge maths interview! What a legend

  65. EthanTronYT - Fortnite, Vlogs and More! says:

    This has got to be the MOST concise explanation I have ever heard of such a convoluted subject

  66. Billy Jolly says:

    There was a name David mentioned before the big bang (Not knowing before), but called in the discussion it something like "Type T Co 0" That might be not what he said but is there actual word he gave i just been looking it up. Anyone know?

  67. Sime Yabate says:

    By far this is one of the best if not THE best explanation of physics!!!
    I wish I could give him 5*

  68. محمد اسماعيل says:

    The string theory of Italian origin is the evolution of the theory of macaroni

  69. slyker5 says:


  70. Cid B. says:

    "Things on the left that go 'bang' when you put them in water and things on the right that don't do much of anything at all." Why couldn't my high school physics teacher be this guy!!

  71. froggyNotGreen says:

    If youre into science videos on YouTube and you don't end up at fields, youre not doing it right. This is a dead end atm and we need to burst past it and see what's on the other side

  72. froggyNotGreen says:

    2 years since they video, what progress have we made so far in quantum field theory?

  73. Faceofthesun says:

    I theorize that matter could have been formed from oscillating Higgs Bosons, in the Higgs Field. If you have seen pictures of water drops falling into the water, then you will have noticed that a droplet sometimes forms and ascends. Now if you imagine that the water is the Higgs Field full of energetic Bosons, then one could imagine the ascending droplet to be analogous to the formation of a fully independent droplet of matter having been formed out of the Higgs Field and Bosons, in other words, the Higgs Field forming a 'droplet' of matter within the Larger Higgs Field . But when it falls back into the Field'so to speak' it does not merge with the Field but remains an independent atom or piece of matter with the two dimensions folding in to form the droplet, which becomes three- dimensional matter. This is an oversimplification of the multiple space- time dimensions that could be involved.

  74. martin jurgensen says:

    There are far more elements than what this downclock pretends to think he knows,in time and space!

  75. Erba Lumkan says:

    He's a theoretical phycisist. In other words: he plays with ideas and mathematical formulas that have nothing to do with reality.

  76. Jagadeshrao Thalur says:

    schrodinger eqn is not the heart of nature for sure, the philosophical debate still stands about the wave function, matrix mechanics bohmian mechanics

  77. Michael Elbert says:

    So you're saying when it comes to quantum field measurements you can only hope to get an average or certain probability never and accurate answered right.? I mean the magnetic moment of the electron.
    Myself I feel like we should not try to measure every field, every part of it, just measure what you can measure .rather than getting a momentum and position at the same time. Can't e you just get the momentum and position of the two closest things together that u can.And go from there.

    In other words go around the uncertainty principle by the way Lee universal computers use all kinds of shortcuts I can name a few this is one of

  78. Ed Felty says:

    The Higgs-Bosun is smaller than the Quark.

  79. Jeffrey says:

    so very enlighting … but what is the force that caused the BigBanG …is there a God afterall?

  80. YoutubSUCKZ says:

    does the royal institution only invites professors who love to *SMACK*??

  81. Radar Blue says:

    Great stuff . I just cant contain myself. the Theroy of Everything. Everybody knows that Einsteins Gravity models is not entirely correct. For instance, there is no evidence of Dark matter or Dark energy except as a tool for gravitational theorists. How can you be shure that There is a magnetic B-field inside Light , when light , is unnable to create a response in iron filings, like a magnetic field does ? A hint, Light can induce a current in a coil, just like an E-field, but it does not mean, electrons move along the light wave. If so it would be called an Arc, lightning strike. Also an electric cable and a fiber optic cable is "galvanically Insulated" meaning they dont interact, and can be lain side by side on the cable tray. The concept of Electro Magnetic filed as a combined unit is in my personal opinion, plainly wrong . Fred Hoyle has another theory than the Big Bangers, That is opposing the Inflation model and the Big Bang. the COBE experiment is also shady, for how long was the shutter open on the satelite photo lense ? the lecturer is great. But the danger of being a pure theorist, is that you have to trust the word, of another . Another pun to the Theorists is, Anything can be expressed with numbers, like a painter can paint any motive on a canvas. And as the nightmare of a project planner : Everything works on the drawing board, until you start building . Its not just hard work that is required, but also to tear up old dogmas (maybe just a few adjustments like flipping the polarities), that may be the most difficult, some of the listed above . Another being the Benjamin franklin who said the electricity moves from + to -. If you state the electron is the moving part and the + is the static Ion part that does not move, will maybe get you rediculed, or frozen out of the science community. B. Franklin is on the Dollar bill for chirst sakes ! Electric current therefore moves from positive to negative for : Historical Reasons ! I can understand why these theories are protected by beak and claws. The road is long, but together we will find the way ! Its not that im jeleous, that it takes 500 experimenters but the one guy who writes the Theoretical math expression gets all the credit 🙂

  82. Matt Harris says:

    These people are very cool.

  83. H L says:

    Why would someone go to a talk if they were just going to cough the whole time?

  84. H L says:

    56:45 The United States has spent trillions of dollars on regime change wars in the Middle East (still going on, by the way). 10 billion dollars isn’t much.

  85. A Peppermint Candy says:

    Why is man in such a great hurry to understand everything? Could it be b/c they can sense their end is close?

  86. david marilley says:

    Why would anyone characterize the Higgs as anything but a field?

  87. sunmanpatoo says:

    No longer can the world afford to laugh at Hindus when they speak of the "three" fundamental deities, Brahma, Vishnu and Shiva.

    Meanwhile, the Vedic Scriptures and Krishna consciousness are neglected by modern scientists and thinkers but these tomes have everything the scientists are now discovering.

    Hare Krishna!

  88. Dirk Knight says:

    Now this is a talk that everybody interested in modern physics should watch. Very nice.

  89. Andrew Calvert says:

    Wow these pseudo scientists really are out of their minds ,tesla said it best about the scientists of today.

  90. Michael Hopkins says:

    I actually own one of only three known, working Faraday Homeopolor motors. I found it at a curiosity shop, all rusted up and fully restored it. There are a couple of vids on youtube of them… but the two others I have found, they forgot to replace the lubrication system on them. Quite an interesting piece. Mine is about 100 years old and used to be an air pump for a fish tank.

    Now, I use it to demonstrate vector calculus… and how electrons move through a magnetic field.

  91. Nautilus1972 says:

    When I was in school, there were a lot of blank spaces on that periodic table!

  92. Rod Berg says:


  93. Chuck Beatty says:


  94. Dadson worldwide says:

    Its 1041 amino acids that are required for life and mathamations say that if you filled the oceans with them and give them 4.6 billion years to rub and mix that the odds against just 1 correctly and randomly joining together in the right order is 10 to the 104 th power. Now you heard even smaller odds of fine tuning in this video .
    But this alomg with grouping all the requirements for this universe to be this way is so great yet is ignored by many.
    Id say today more physist believe in a creatir ,fine tuner or god than did going back the past century or 2. Im guessing this has a lot to do with that.
    for what ive learned as a hobbiest has more and more pointed to god.
    as a kid 50 years ago this wasnt the dominant idea we was taught .

  95. Yeah Boiii says:

    The answer is 3.

  96. Eric Meece says:

    The first philosopher Thales said in c.580 BC that the world is made of water. That's similar to what Tong says that the world is fluid.

  97. Rekuzan Rikudo says:

    LAWS of physics!!! falls over laughing GOOD one Newton!

  98. Vik555 says:

    the most important thing i got is everything is made of fields and there are 12 matter fields and 4 force fields and higgs field 36:25

  99. ChildOL says:

    The universe is a construct similar to a computer simulation governed by mathematical rules created and sustained by a massive and powerful mind that exists outside of it. Science will catch up to this fact eventually.

  100. Nicole Wolfe says:

    follow wolfeorganicsco everyone

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