Good afternoon, ladies and gentlemen. Can everybody take a seat, please?
Thank you. So it's my pleasure to welcome you to the second Western Lecture.
These lectures occur once in three years.
So in astrophysics, we have the highly lecturer for two years, and then we have the Western lecture and then two years, the Halley Lecture again.
So it's wonderful to have this opportunity to celebrate our subject.
And this year actually we have some additional sponsorship,
the foundation having a workshop in Oxford this week and they decided they wanted to sponsor the lecture as well.
So we were happy to to take their largesse.
And Christchurch College, Christchurch of course also sponsors the lecture series and the workshop that we've been having.
We're having a workshop on stimulating the universe in Christchurch for a couple of days and many people in the audience are attending that workshop.
So far I think we've not quite got to the stage of rooting out the necessity to observe the universe,
but we are doing pretty well at simulating the universe.
So so it is my great pleasure to introduce to you this evening a person of great distinction and a very good friend of mine, Carlos Frank,
who is the professor of astrophysics at the University of Durham and director of the Institute for Computational Cosmology.
Karwal sees a star of our subject in a subject that has bright stars.
He is a supernova.
There are there are many awards and prizes that he has been awarded a list far too long for me to list all of them, and I will mention a few.
Last year he won the gold medal of the Royal Astronomical Society.
In 2011, he shared the Gruber Prize for Cosmology with his colleagues Mark DAVIES, Georgia staff here, and Simon White for the Cold,
Dark Matter Paradigm 2010, he won the Institute of Physics Hoyle Medal, and he was elected a fellow of the Royal Society in 2004.
So it is my great pleasure to introduce to give the second worth of lecture.
Professor Carlos Frank, how are you? What is this?
Talk about your title. Everything.
Everything from nothing. How the universe was made. Carlos, thank you.
But thank you very much. But we're very happy to be here.
And thank you for that very nice introduction.
I'm glad you stopped because you were making me start looking forward to my own talk, which is never a good thing.
So yeah, I'm glad you remember the title because it is kind of a somewhat cryptic title, everything from nothing or how the universe was made.
But I hope in the course of the next 50 minutes or so, the reason for the title will become apparent.
So it's clear not just from the title, but from the picture behind it,
which I should say I put it here to make Roger and your film nostalgic for Darren,
because Roger and I were colleagues in Durham for many years, and that was the view we had from the roof of our building that.
But as is clear from the title, these two talk about cosmology and cosmology is possibly the oldest science
and it asks some of the most fundamental questions that not your scientists,
but many other people ask questions such as How did the universe begin?
What is it made of? How did it evolve to its present state and what does the future hold?
So these are questions, fundamental questions that go back to the beginning of human civilisation and what could even say that civilised
the beginning of civilisation is defined by the moment where our ancestors began to ask these questions.
The question questions of great interest in many disciplines, but in cosmology and in physics,
we have a particular way of trying to address these questions,
which is following a very well-established and well-tested methodology, and that is the methodology of physics.
So modern cosmology is based on the laws of physics.
And for those of you who have the misfortune of not being physicists, let me remind you what a lot of physics is.
It is essentially a rule about natural phenomena, rules that are almost invariably derived empirically by through laboratories and observations,
and then that expressed mathematically and manipulated through the powerful language of mathematics.
An example is Newton's law gravitation. I'm sure you're all familiar with that.
The God's law, Boyle's law, quantum mechanics, relativity.
These are all examples of the laws of physics. Now, as I said, the laws of physics are discovered here in the laboratory.
And in principle, we have no right for those laws to apply outside of laboratories.
But one of the amazing features of modern astrophysics and modern cosmology is the realisation that the very same laws of
physics that we use here on Earth seem to describe phenomena everywhere in the universe at all times when conditions were very,
very, very different from the conditions that prevail in the laboratories today.
So the universality of the laws of nature is a very profound aspect of a
universe which I just going to take for granted in the remaining of the stock.
Now. And so the. Title.
Going back to the title, as I said, Cosmic history is a story about nothing.
So I'm going to spend 50 minutes talking about nothing, and you might wonder why you're not outside enjoying the sunshine,
but I hope you will not regret it at the end of this lecture.
So let me tell you a little bit about nothing. And in fact, as the title says, I'm going to talk about had nothing, became everything.
So let me tell you what I mean by nothing, because I'm using the word nothing in a technical sense.
I'm using it in the sense that we use it in physics, where by nothing we mean the vacuum.
And it turns out that contrary to what the word might conjure, the vacuum is not empty.
It's actually full. It's full of something that we call vacuum energy.
And what we will see, this vacuum energy plays a key role in the entire evolution of our universe.
So I have a animation of the vacuum and so as close as I could get.
So let me tell you what we mean by vacuum in physics.
Imagine you have a chamber in the laboratory and you connect it to a pump and you extract everything out of that chamber,
every single atom, until you have no atoms, nothing left in it.
Of course, we cannot do that in practice, but at that point, you would have a perfect vacuum.
Nothing. And no matter in it, nothing in it. And if you were able then to go and look at what was left inside this chamber with a very,
very powerful microscope, this is exactly what you would see.
You would see that the vacuum, even though you've emptied it of everything, is not empty, it's full of energy,
and that this energy manifests itself in matter and anti-matter that are spontaneously created out of nothing.
Particles of matter and antimatter that when they collide, they inoculate producing energy,
which then decays into matter, and antimatter which then decays into energy.
And this is going on and on and on and on.
The vacuum is actually bubbling with matter and anti-matter, and that is what we mean by the vacuum and by the vacuum energy.
The energy of nothing. Now, I hope you survive that. That's the hardest part of this lecture and may get easier from now on.
And what of the most amazing propositions, not just of cosmology, but of the whole of science today, is that everything we see in the universe,
including galaxies, including stars, planets, and eventually all came out of the vacuum, as I will now explain.
Now, so the up for us cosmology is the smallest unit of interest really is the galaxy and these are
the building blocks of the universe structures or collections of up to 100 billion stars or so.
And that many of these around the universe.
We live in a galaxy very similar to this one and we are here located two thirds of the way from the centre of the universe on purpose.
Because all my colleagues in physics think I agree with them.
They always think that at the centre of the universe here in Oxford,
I have to keep reminding them that that's not true, that two thirds of the way from the centre of the Milky Way.
Now, so let me try and give you a flavour of what I'm going to be talking about by showing you a movie.
Now I just I wonder whether we can get the lights down so you can see these.
Oh, I can do that myself. Right. Aha. You should see me trying to do this in Durham and up surrounded by a cloud of undergrads who say to me,
You're the professor, Roger, you're the professor.
You go now. So even lower.
Yeah, let me see. As low as we can get the.
Okay, so we will. So this a tour around our local universe.
It's a movie made from real astronomical data.
All the data in there are real and it's a movie thank you graduate that was
made by a colleague in Hawaii called apparently whose name you can see there.
And that is an animation that will take us around a local neighbourhood.
And we begin by heading towards the constellation of Orion, which I'm sure many of you will recognise.
And here is a strange object called the Orion Nebula, which is a cloud of gas and dust where young stars are continuously being born.
The Milky Way is making about one new star every year, and the light from the stars is another example.
The whole nebula. The light from the stars illuminates the residual cloud of gas and dust from which the star formed.
And actually stars turn out to be born, usually in small groups.
Here's the very famous nebula called the Carina Nebula, where you can see if you.
Have good eyesight, that there's several stars being born there at the same time.
Now, however, not all nebulae are about birthplaces of galaxies.
Some of them might be opposite that graveyards. And that is a very famous nebula called the Crab Nebula.
Inside it, there is a remnant of a star that died because it ran out of fuel.
Stars shine because they undergo nuclear reactions in the centres.
These one run out of nuclear fuel and ended up leaving a remnant before called pulsar, which you may be able to see pulsating over there.
Now, here is the only bit of artistic license in this movie where we're going to leave our galaxy and look at it from the top of it.
We cannot do that. But it's a galaxy very similar to the Milky Way. Galaxy is about 50,000 light years across.
So it takes 50,000 years for light to travel.
And so, as you can see, communication with colleagues at the other end of the galaxy is not for the impatient.
Now, here, we're now heading towards the nearest large galaxy,
towards the Andromeda galaxy that you see here has a neighbour called M32, which itself has its own clouds of gas and dust.
And these Galaxy two is making about one new star every year.
So these are Andromeda at a distance of about 2.1 million light years.
Again, not suitable for snappy repartee with extraterrestrials and that we now leave a neighbourhood.
We're going to head to the subject called the Virgo Cluster of Galaxies.
But before we do, that will take a small detour to admire these incredible things that nature has made.
I mean, these objects are enormous. They contain hundreds of billions of stars, and they are truly beautiful and spectacular.
Here is the galaxy that's interacting with a neighbour. And you can see here galaxies are not distributed at random in the universe.
They follow patterns. Here is a very good cluster of galaxies,
a collection of thousands of bright galaxies which lies at a distance of about 30 million light years from us.
And that in the centre of Virgo there's a very famous galaxy here called M87.
This is famous, amongst other reasons,
because it has a very massive supermassive black hole that weighed 2 billion times as much as our sun in the centre.
And this black hole is busy eating material around it and you can see possibly the effects
of the digestion of that material in the form of a small jet that you can see there.
So this is the universe around us and this is what cosmology would like to be able to understand.
A great project. It really takes me back to a days in Durham where Roger could always make things work, but I could break them.
He would fix them now.
So even though there's so many galaxies in the universe, about 100 billion galaxies in the visible universe, each with about 100 billion stars,
we actually now know that the material that makes galaxies and stars and planets and people,
it's actually a very small fraction of what the universe contains.
So what we call ordinary matter,
that is matter made of the ordinary atoms that you can find in the periodic table makes up only about 5% of what the universe contains.
About 25% is dark matter.
That is battery that does not emit light at any wavelength in the electromagnetic spectrum.
And that makes up five times as much matter as a normal matter made of atoms.
But we don't know that the lion's share of the universe is not even matter.
70% of the universe is something that we call that candy.
And even though we've made tremendous progress in addressing some of the questions that I put up on my face,
life slightly balancing state of play in a subject is that we really don't know what is
either of these two components is so even though they make up 95% of matter in the universe,
we're still struggling to understand exactly what these two components are.
So let me tell you briefly about that, KENNEDY, because that is the more mysterious of the two, the one we would really know very little about,
and that we know so little that in a couple of slides I'm about to show you,
I'm going to bring you up to the same level as the experts who get paid to work on the subject.
Before I do that, let me just apologise that I have to do a few antics here.
That's because I have a backache and that. And then when my vegetable, after I talk for 10 minutes at least a good clock to tell me when to stop,
but my vertebra starts compressing a nerve and you have to sit down for a couple of minutes, and then the vertebra moves and then I'm happy again.
But so you just ignore my antics here. And let me tell you then a little bit about that.
KENNEDY So the. Dark energy has to do with a cosmic expansion.
That expansion of the universe was discovered in 1937 by this man in 1929 by rather by this man, Edwin Hubble.
In the days when, as you can see, astronomers were allowed to smoke in their offices.
And even more importantly, they were allowed to have blackboards, which we are no longer allowed, at least not out here.
You are here, right? I should take those views back to that.
But Edwin Hubble Hubble looked at galaxies around us and discovered that with the exception of Andromeda,
all the galaxies are moving away from us with a velocity that is proportional to the distance.
In other words, the farther away a galaxy is, the faster it is moving away from us.
And all galaxies are, with one exception, dropped by that because of the gravitational pull of the Milky Way, it's bringing it back to Earth.
But all other galaxies are moving away from us in this sort of regular pattern.
So what he had discovered was the expansion of the universe. Now, that was in 1929.
Then at the end of last century, other astronomers made a very remarkable discovery,
namely that not only is the universe expanding, but the rate at which it is expanding is increasing with time.
So the expansion is getting faster and faster and faster and faster.
And that is a big surprise because if the universe was just made of matter, then you would expect, as Americans say, gravity sucks.
You would expect gravity to pull the universe back. So the expansion should be slowing down.
Before we had was not there. But in fact, the observations show that contrary to that, the expansion is accelerating.
And that means was interpreted for reasons of describing the minute as implying that the universe is full of something.
And in science,
you always have to be suspicious when you find names that are slightly odd just means that the people who make these names know nothing about it,
and that tenet is the best example of something where the darkness really has to do with our understanding of what this God wanted this,
but in spite of that, what the substance is, rather that in spite of that,
the discovery of the accelerating universe and the Nobel Prize in physics to three colleagues in 2011.
So what is this dark energy?
Well, we don't really know what it is, but it probably has to do with that vacuum energy that I was talking about at the beginning.
And the reason is the following. So imagine two galaxies.
The universe is almost empty that these island universes called galaxies.
Between them, there's nothing. There's a vacuum much better than any vacuum that we can make on earth.
So imagine two galaxies. There's nothing in between. And they are moving apart from one another faster and faster and faster.
So what that means is there is nothing in the nothingness.
There must be something that's pushing these two galaxies, and that something is what we call the dark energy.
So in form of repulsive energy, and because there is nothing in between,
the galaxies surely must have something to do with empty space with the vacuum.
So we think then that whatever the dark energy is, it must have something to do with vacuum energy.
But that's only the sort of hint we're following at present.
That's about it. That's about all the sum total of scientific knowledge in the subject that can see some people who work on dark energy.
So I hope they won't disagree too violently with me.
I mean, there are many other many other avenues that are being pursued.
But I think that summarises where we are now.
We know a lot more about dark matter and which is in fact one of the subjects in which I specialise.
And let me tell you a bit about dark matter now. So for dark matter, we do really have some quite straightforward evidence.
And the eminence comes from various sources,
but the most impressive one has to do with the way in which stars rotate around the centre of the galaxy to which they belong.
So we know since Newton how to understand the rotation of, say, planets around the sun or stars around the centre of the Milky Way.
And there's a very simple formula that Newton discovered 350 years ago, 300 years ago or so,
which describes how stars should be moving around the centre of the galaxy.
And what these law tells us is that if all the material that makes holes the galaxy
together gravitationally is contained in the brightest parts of the galaxy,
then the velocities should be falling off with distance.
That's what simple Newtonian theory predicts. But I was confused about these the other day.
I was in London walking in the streets and I was thinking about this.
Something I couldn't quite understand. And then fortunately, I run into Newton's in self and appears.
He said, Come back and run into me in London.
That's why I have that silly grin, because I was able to understand by talking to Newton here,
he's more than the incarnation what the laws of gravity are all about.
It is new that we look at the most exciting things. They know the job.
It is Newton, a bit older than the one in the picture here.
But nevertheless anyway. And things better than. So the way then we know that our Milky Way is embedded,
swimming in a pool of dark matter is just by observing that the stars rotate much too fast to be held in place by the gravity of the visible matter.
So the stars, the velocity far from falling off, away from the centre, essentially stays constant.
And that means that there must be some other source of gravity other than the gravity that we see in the core,
the gravity that are produced by the material that we see that must be keeping those stars in place.
And that is what we call dark matter. So the way to think of the galaxy is as a pool of light embedded in a large clump of dark matter,
which for reasons I've never really understood, astronomers call that very haloes, and I really don't know why.
Halos. Halos, to me, evokes the saint with the halo of beatitude.
And that's not what astronomers are like. Yet we refer to this objects as dark matter halos now.
So they're really globs of dark matter and they are responsible for keeping galaxies in place.
Now, what is the dark matter clearly is fundamental question in modern physics, and we don't yet know for sure,
but we have a very strong hint that whatever it is, it has something to do with the universe.
And it almost certainly is some elementary particle that was produced when the universe was very young,
but one billionth of a second of one billionth of a second after the Big Bang.
According to theories of particle physics, the universe had cooled enough that a process called symmetry or supersymmetry rather took place.
And I mentioned supersymmetry because it may be in the news in the next year, for reasons I'll tell you in a minute.
So supersymmetry is the new Higgs. I'll tell you more about it in a minute.
But when the universe was about a billionth of a second over, then supersymmetry prevailed.
And as a result of that, elementary particles that would produce, produce in enormous numbers,
that would produce all the gravity needed for dark matter, could have been generated during these period.
And that often goes also by the name of cold, dark matter that Roger mentioned in a very nice introduction.
So now what is the dogmatic? Well, say, I think the working hypothesis of most physicists is that it is some form of elementary particles.
So that is the starting point for the vast majority, not all, but for the vast majority of physicists.
It's an elementary particle, almost certainly from the universe.
And crucially, these supersymmetric particles are very different from the ordinary particles that make up the atoms of which we are made.
So physicists agree with these, but I was actually quite surprised to realise that also politicians seem to know about this.
Now this Angela merkel, somebody has said to her, what if the documents in elementary, tiny elementary particle.
Now it's not surprising because she's, after all, a physicist.
She has a page in physics, solid state physics, but the thing wrong with solid state physics.
Now, I was surprised, though, that this chap also knew. And but that's understandable.
Tony Blair grew up in Durham, about 100 metres from my office.
So he he has every right to know what the dark matter is.
But of course, not all politicians are equally. And what that was a mistake, because, of course, that's what matters comes to him and the poor.
Nevertheless, that at least, yes, it's good to have friends in high places.
He knows this man who's telling him what to talk about. It is that, of course, he learned very, very quickly what took him a while.
He's got to go to that. But finally he's got it. And that's why he's now one of the great champions of of elementary particle dark matter.
And this fellow for good measure anyway. So no, but the reason I show you these pictures is I have a good reason for this, and that is the following.
Politicians work in a strange way.
I've always admired. They they they they have authority. They tell you I'm going to put up the taxes on your pension, and they do it next time.
If you're on a pension, it's smaller than it was before. So they have this authority and this is exactly inimical to the way in which we do science.
So it's not enough for even Angela merkel to tell us that the dark matter is an elementary body in physics.
We got to verify that by evidence. And so that is the key difference, I think, between physics and many other disciplines.
And in physics, we don't take anything for granted.
We search for empirical evidence and the search of dark for dark matter.
And if the experimental physics activity for those of you who've never seen that experimental physics, that's what they look like.
And they're all like this more or less.
And there are actually several ways to look for dark matter.
One, it goes back to what I said a minute ago. I talked about supersymmetry a billionth of a second after after the big bang.
And now, if you recall, when the LHC in Geneva was first opened,
it was billed as being capable of producing conditions that existed in the universe a billionth of a second after the Big Bang.
And that's why many physicists expected that the first interesting result from the LHC would be the discovery of supersymmetry.
Now it didn't happen, but now the LHC has been revamped, its energy increased,
and it may well be that this is the next great big discovery and we'll all hear about it in the news,
because if the LHC discovered supersymmetry, it would amount effectively to making dark matter in the laboratory.
So that was the Higgs. That was last year's news.
And we still haven't found dark matter, but it may well be that we will find it at least evidence through supersymmetry in the next year or two.
Now, that's only one way, but in fact, if the dark matter is what I think it is, this room is full of it.
We're swimming in dark matter. But these particles, and that's why they're different from ordinary matter, don't interact with anything.
They just stream through our bodies at a rate of billions of dark matter particles per second, and they just go through everything.
And that's why they're so difficult to detect.
They produce gravity, but they do not interact with anything, and therefore they do not interact with a detector.
And that's why they're so difficult to detect. However, when I say they don't interact, I don't really mean it.
They do interact, but very, very weakly. And so there are experiments that try to exploit these very weak interactions with with dark matter.
They're usually conducted at the bottom of minds with an experiment very close to where I am place called the Bowlby mind the deep inside.
The mind.
These experiments take place because the earth between the surface and the detector is used as a sieve to filter out all sorts of cosmic rays,
as we call them, particles that rain from outer space onto the earth that would interfere with the experiment.
But here in the bottom of the bogie mind and other places that detectors where they expect occasionally for
one particle of dark matter to hit the nucleus of an atom in the detector and make it wiggle a little bit.
And the experiment consists in trying to detect those wiggles and separate them from the bankrupts.
These guys have given any results yet, but the there has been quite a lot of progress.
The sensitivity of these instruments has increased by many, many,
many orders of magnitude in the last 20 years of 25 years since the first experiment was built, and are now detectors like these all over the world.
Here's a bunch of VIP's visiting and myself visiting the bovey mine.
The reason I like to show this picture is because there were several physicists here,
but there is only one who works in the mine and you can tell who it is.
The only one who is not smiling is working in the mine really is not for the faint hearted.
So we don't yet know what the dark matter is.
But I think this is one of those aspects of my subject where I think we have every reason to
be optimistic that in the next few years we will have the answer to this part of the riddle.
But you've been saying that for the last ten years or so, but I do think that we're close now.
So now why? Why why have I spent all my life working on dark matter that I could see many people here that do the same and they bring some young ones?
Now, why is dark matter so important? Well, obviously, we want to know what the universe is made of.
But that's only one small part of the story. To me, the dark matter is important, not just out of the curiosity about what our universe is made of,
but because of the crucial role that dark matter plays in explaining why the universe looks the way it is.
Because, as I will show you in the next few minutes, it is thanks to the dark matter that we're here.
There was no dark matter. There would be nothing in the universe.
It would be really, really boring.
There would be no galaxies, there would be no stars, there would be no planets, and there would be therefore no people.
So in a sense, I think searching for the data, the dark matter is, in a sense, searching for our own identity.
So the dark matter plays such an important role because it is the gravity of dark
matter that drives the formation of galaxies and other structures in the universe.
So let me tell you a little bit about that,
which is another of these amazing subjects where there's tremendous progress at the workshop I'm attending here,
what a lot of it has to do with building instruments to really look at how this whole process of the formation of structure in the universe unfolded.
Now, if we want to ask the question of where the galaxies come from, we have to go to early times, in fact, very early times indeed.
The story begins when the universe was a decimal point, 35 zeros, and then one that fraction of a second after the Big Bang.
That's when the story of the formation of the structure of the universe begins.
And guess who plays a key role? The dark energy and the reason that dark energy plays a key role is twofold.
We now think that the universe very early on then to the -30 5 seconds after the
Big Bang underwent a fairly dramatic episode because according to this view,
which is the mainstream view in cosmology, when the universe was born,
it had too much of these vacuum energy and it got rid of it by expanding very, very rapidly for a very brief period of time.
This goes by the name of cosmic inflation,
and it is a phenomenon whereby this excess of dark energy that the universe had at the beginning was dissipated by the universe,
expanding very, very rapidly so that it grew from the size of a proton to the size of a football in about ten to the -30 5 seconds.
And this is the role that Kennedy plays in causing inflation.
But that Kennedy is a quantum process because it has to do with matter and antimatter.
And you can see that these vacuum, if it plays a role, it's always fluctuating.
These are called quantum fluctuations. And these flux continuously fluctuating energy of the vacuum goes by the name of quantum fluctuations.
And the proposition that I'm going to make next is that we all come from a quantum fluctuation produce during inflation,
ten to the -30 5 seconds after the big bang. So that is the proposition of modern cosmology.
When these phantom fluctuations did during inflation is to seed the universe with tiny irregularities produced by this continuously fluctuating few.
As the universe expands very rapidly that these fluctuations become imprinted as genuine fluctuations in the energy density of the universe,
such that the universe would be slightly denser in one place, slightly less dense in another place.
And these are tiny, tiny irregularities. And the proposition is that it's where galaxies come from.
So according to inflation theory, galaxies grew out of these tiny quantum fluctuations.
Now so and then therefore but the whole of the structure of the universe goes back to this process of quantum irregularities.
I post here because. If you hear this for the first time, you should be thinking what these bands.
They can leave of your senses. Quantum fluctuations.
You know, these are tiny little things that happen in the microscopic domain,
making a galaxy like the Milky Way with the hundreds of billions of stars.
Well, I will show you evidence for that in a minute.
But let me first illustrate what I'm talking about with this movie,
which is a simulation of a patch of universe 500 billion light years, which was seeded with quantum fluctuations.
The initial stage is the clock. Millions of years was very, very smooth.
And you see here how this sphere in a computer seeded with quantum fluctuations very quickly, only through the action of gravity,
which is the only thing that is included in the simulations, goes from very being very, very smooth to being highly structured.
So there's a hint here from simulations that we may be onto something good.
Nevertheless, I think that if Einstein or the Newton were to walk through his door and heard me say what I just said,
I often wonder what they say, because I say that, for example, even like quantum mechanics, there are long quantum fluctuations.
And Newton, likewise. Newton thought the universe had been there forever.
And so what do they think? Well, I'm sure I know what Einstein would have done.
That's what I instead would have done. And and this is, I think, probably Newton's likely reaction now.
But the point is, going back to the beginning of my thought, the point is that in physics.
Propositions need to be verifiable by experiment.
Now, this, as you will see, is not an easy experiment to do.
But this is why in physics I can turn up in my institute and come up with the most outrageous idea in the world,
and they will still get paid at the end of the month if my outrageous ideas testable.
It doesn't even need to be right. Just needs to be testable. Now it turns out that the proposition I just made that quantum fluctuations at the
origin of structure when amplified through the action of the gravity of dark matter.
That proposition, amazingly, is testable. Now, if you think about it, it's not obvious we should be testable.
But we are very blessed in my subject because.
In my subject, we have a crystal ball, and the crystal ball is a gift that nature has given us.
And it is to do with the fact that light travels only at a given speed.
Light travels at a speed of 300 kilometres per second.
And what that means is that as we look so, for example, so that light emitted from an object which is far away from us takes some time to get to us.
And then therefore it reflects the conditions that prevailed when the light was submitted.
So when we look at the sun, for example, we realise you can do in Oxford, not in Durham, but in Oxford you can.
You don't see the sun as it is now. You see the sun as it was 8 minutes ago because that's how long it took for the light from the sun to get to us.
And that's because light travels through finite speed.
So the farther away an object is, the longer its life has been travelling and the farther into the past that we can see.
Wow. So the first light that we can see, in fact, tells us about conditions that prevail very early on in the universe.
In the universe was very hot. And throughout its 13.8 billion years of existence, it's been expanding cooling.
As it does so, the early universe was actually very foggy because matter was broken up into particles.
So light kept colliding with particles bouncing around and that created the fog of the early universe.
But when the universe was 350,000 years old, which is the human equivalent of one day in the life of a human.
So when the universe was about in human terms, one day old, 350,000 years after the big bang,
the fog of the Big Bang lifted because the first atoms in the universe formed.
And so these collisions of particles of light with particles of matter stopped, the fog of the big bang lifted and light was emitted.
And that light has been propagating from us since that early time.
These photos of light emitted at that time have been travelling freely throughout the entire cosmic history.
And amazingly, they were discovered in 19 5064 by these two gentlemen, Arno Penzias and Bob Wilson,
who accidentally make many of the great discoveries of science, stumbled upon these radiation that seem to be coming from everywhere.
And that was very, very cold at a temperature of only 2.7 Kelvin,
2.7 degrees above absolute zero because the universe is so old that this radiation has cooled down to these very low temperatures.
They discovered it accidentally. They were looking for that.
They were interested in trying to find that radio emission from the sun.
And this was a known one the background and on a where's this a beautiful study that I don't have time to tell you.
But they were completely unaware of this until accidentally they heard that two,
three people in Princeton, they were in Bell Labs just a few miles from Princeton,
three people in Princeton who were Bob Dickey, Jean Peebles and David Wilkinson, where actually who knew about this radiation were looking for it.
And it was in an aeroplane journey that the news were spread and they had actually stumbled upon the evidence for the Big Bang.
So we have had evidence for the Big Bang Theory since the 1960s.
But according to inflation,
this early universe was seeded with these momentum fluctuations and these quantum fluctuations would propagate during the foggy phase,
but they would still be there when the radiation emitted.
So according to the theory of inflation, we should see in the radiation from the from the radiation from the Big Bang,
which it's called the microwave background radiation,
because it's seen in the form of microwaves today in that radiation, which is the evidence for these quantum fluctuations.
And what would they look like? Well,
it turns out one can calculate that using the laws of physics and the evidence for these small fluctuations should be
labelled patches where of cold and hot spots in the temperature of these relic radiation left over from the big bang.
So if inflation happens and if quantum fluctuations seeded the universe with small fluctuations,
they should be reflected in the temperature of the radiation.
And the physicists can make predictions that forget that not to ignore the technical details,
but they can make predictions for exactly what this pattern of cold and hot spots should look like.
And the reason I show you these is just to say that it is complicated.
It's not something. It has a signature in it. Well, so the in 1992.
Nasser launched a satellite called Kobe, the Kobe back of Explorer.
And this is what Kobe saw. So what you see here is a map of the temperature of this radiation leftover from the Big Bang,
radiation that's been travelling freely until it is detected in a satellite.
And this a map of the temperature of that radiation.
And as you can see here, it's not smooth. It has spots, hot and cold spots, exactly what the doctor ordered.
So much so that these media, these discovery made headline news all over the world.
This was the front cover of the Independent in the days.
If you remember those of you who are of a certain age where the newspapers were still reporting on science in the front page,
that did happen is very dense, I must say.
I'm embarrassed to say this, but I made a contribution to this.
That was the best thing for posterity here in the Independent.
Those of you in the front row could see that. Carlos Frank, an astronomer at Durham University, said yesterday.
Oh, wow. So this is my great contribution to astrophysics and I think my wife sitting here.
So hopefully she put that on my epitaph. But yeah, it really was.
It really was a wild moment. I couldn't believe this.
Now, I must say, though, that one reason for that is this was, as you can see here, April, where you can't anymore.
But it was 22nd of April of 24th of April of 1992.
Now, this was Nasser. Nasser had embargoed the news until midnight Washington time, which happens to be 6 a.m.
Durham time phone rings at 6ami pick it up and I have this American reporter saying to me,
Hey, Dr. Frank, we just discovered the temperature fluctuations in the microwave background.
What did you say at 6 a.m.? Wow.
And anyway, there's more to that story, but that for another time, that that discovery earned George Smoot a Nobel Prize in physics in 2006.
This radiation has been remeasured with greater resolution a decade later by another great satellite W by the W,
by the way, stands for David Wilkinson,
one of the three people I mentioned a minute ago in Princeton who died just before the instrument hit detector he did develop was deployed.
And you can see the same patterns. But now we've been in resolution.
And then, of course, the Europeans caught up a decade later with their own mission called Planck wage increase,
the resolution and the sensitivity tremendously. And so this is now what we know about the microwave background.
Radiation is the state of the art now. So these are the predictions about what the temperature that I show you, this plot.
I again, I don't want to go into the technical details, but what it is, is just it tells us what the pattern of hot spot should look like.
And as a function of the angle of the sky. The point I want to make is firstly that this theory was some of the theoretical predictions based
on inflation and based on the idea of cold dark matter where published in 1982 by Jean Peebles,
they would work also very extensively here by Georgia staff you and the bond and
these were predictions that were made in the 1980s based on the idea of inflation,
based on the idea of quantum fluctuations and based on the idea of dark matter and of cold, dark matter.
And this is what the corresponding plot from Planck looks like.
And you can see here, this is just from earlier this year.
This to me when I look at I've looked at this plot dozens of time, more hundreds of times and.
It leaves me speechless because it really is astonishing.
What you can see here in my mind is one of the great triumphs of human civilisation.
Why? Well, because what you see here is some theoretical prediction shown here by the Green Line,
made by physicists using the tools of mathematics and using the laws of physics,
extrapolated from Earth down to our own, the beginning of our own universe.
So it's a theory about the beginning of our own universe.
So the fact that for whatever reason you humans have evolved to have the ability to make these theories is already astonishing.
But the fact that these same creatures are capable of building machines that they can
launch out of the planet and measure these tiny signals because they are really tiny.
That one part in ten to the five shown here by the red dots is incredible.
It really is quite amazing.
So I think the first time a plot like these was shown to an audience of astronomers, an early version of this, there was a standing ovation, ovations.
The only time in my life that I've seen that. And it is to me, really an enormous triumph, not just of cosmology, not just of physics,
not just of science, but I think of human creativity and human capabilities right now.
So I'm nearly done. And but even though we're only 350,000 years in from the beginning,
the rest is much easier because the rest is to work out how these small perturbations that we see in the microwave background radiation,
how they evolve to produce the galaxies that we see in the universe today.
That's a much easier project, no problem.
Because we can deploy big computers to solve the equations of physics as they apply to the expanding universe.
That's something that we know how to do quite well. So let me just finish off with a few movies.
Here's a movie that shows from quantum fluctuations how the halo of our own Milky Way galaxy would have formed.
So here's the clock ticking again in billions of years.
And it was very smooth, really times that which is this quantum fluctuations that we're talking about.
This is the dark matter called dark matter. How it shows you how sky the gravity of the cold.
Dark matter amplifies these small quantum fluctuations, producing at first a very intricate pattern.
It's a small version of something that cosmologists call the cosmic web.
You see all these lumps? This is just where gravity has amplified these quantum fluctuations and that these lumps
arrange themselves in a way we understand into mathematically into these filaments.
And then it's just gravity that attracts one clump for the other.
When they collide, they fuse together, building larger and larger structures.
So this is known in the trade.
It's hierarchical clustering and describes the way in which a universe is made
of called dark matter would have resulted in a halo like that of the Milky Way.
Now that's just dark matter. Here's another view of dark matter now at the present day.
So here we're just cruising through the universe today.
We had the dark matter glasses, and we were able to travel very, very, very fast.
We would see the universe is seeded with these halos everywhere, which is where we expect inside these halos.
We expect ordinary matter in really times made of gas to collapse due to the gravity
of the dark matter halos and then fragment into stars and produce visible galaxies.
Now all that's going into these simulations is inflation, quantum fluctuations.
And for the dark matter problem only. The only thing we need is relativity.
Because the universe expands and gives gravitational physics, which is physics.
We've understood now for a long, long time, for over 100 years in the last year or so, efforts going back decades have begun to bear fruit,
where we now try to simulate just the evolution of the dark matter,
but also the evolution of the ordinary material that makes the stars and the galaxies.
So this comes from a project I was just published earlier this year called The Eagle Simulations with Eagle stands for Forget Evolution,
An Assembly of Galaxies and the Environment. And it shows the evolution of the various components of the universe.
Yeah. Here you see. First up, dark matter just as before evolving.
Here's the clock, which is clearly visible, but it doesn't really matter. It's very early times.
What we see here is quantum fluctuations. And how they cause the dark matter to to assemble into these filaments.
But now we're going to change to gas. So what you see here, we're zooming into one object.
And now we're looking at gas. Not a dark matter anymore. And here, this is an object of interest.
There was a quantum fluctuation there. And that is now, as you can see, as time goes by, producing something reminiscent of a galaxy.
So here by now, the universe is about 5 billion years old.
Now we see stars. These are now the stars in the simulation.
That's what came out of that process.
And we go back to gas and we zoom further in. The universe is now about 8 billion years old.
And we're looking at the gas again. And this is what came out.
Just from the loss of physics, assuming an initial state characterised, as you said, by quantum fluctuations.
So here's the guys. Here the stock.
And that is a volume of cosmological volume. Now zoom out again and see if we can make a computer.
Not just one galaxy, but many. And I.
Some it's like to be slightly mischievous. So I played a trick.
On some colleagues of my Durham minor. Durham.
I won't mention who they are. I showed them this picture and they say these are observer observational astronomers.
Several of them here. I show them this picture. I said, What do you think?
Do you recognise these galaxies? I can't remember which catalogue I got these from which catalogue they use.
Do you know which catalogue? Well, I got all sorts of interesting subjects.
The Hubble Atlas surely, said two of them. Now they came out of a computer.
These is what we can do in computers today in following this whole structure, this whole.
Building that I described to you this evening. So let me then finish off with a summary so I can tell you really a story about nothing.
I'm sure it doesn't feel now that I've been talking about nothing, I've been talking about quite a lot.
But the story I told you is essentially very simple.
It goes back to the very early universe, been to the -30 5 seconds after the big bang, when due to the presence of the vacuum energy,
the universe expanded very rapidly and this expansion cause more fractures, which we know as quantum fluctuations,
whose presence is detected directly in the temperature of the microwave background radiation.
The heat left over from the Big Bang 350,000 years after the Big Bang.
And it is the amplification of these fluctuations through the gravity of dark matter that produces the universe, which we see today.
So is this is this the end of the story?
Well, no, it's only I hate to say the end of the beginning, but it is only the end of the first part,
because in reality, we don't know what is the dark matter.
I hope it is what I spend all my life working on, but there's no guarantee that it is that we're still to discover what the dark.
But it is. It's a big open question. The subject. That?
Kennedy. I often say that if I lived my life expectancy and my age, I should be around to see this question answered.
But I doubt that will be around to see these one. And.
That's a really, really tough question because we don't even really know how to start trying to address this.
But there are many instruments that are being built,
often at great cost to you taxpayers to try and characterise what is causing these accelerated expansion.
But as of now we know very little about it. And of course the key question is how did the universe begin in the first place?
So let me then conclude, I think I hope I've shown that there's been enormous progress in this subject over the past 30 years of so.
But in my opinion, I think they still owe this is to say the best is still to come.
And I think it's not I must be feeling depressed that day, but I think the best is still to come.
And so look out for the discovery of the dark matter and which I think will give another big piece of evidence for this whole picture.
And but don't hold your breath for that. I get it. I'll stop here.