Okay. So first, I'd like to welcome all of you to the Department of Physics.
And also to welcome you to the inaugural Particle Physics Christmas lecture on behalf of John Wieser,
the head of particle physics of physics and the head of particle physics.
So let me tell you first that particle physics has been studied here in Oxford since the early 1960s, and it's modern form.
That Oxford physicist played a leading role in establishing our prevailing theory of particle physics called the Standard Model.
It's a remarkable theory that in some cases can make predictions with precision of one part in 10 billion.
And it's found to be accurate. A towering achievement that is recognised perhaps as one of the greatest achievements in all the
science over the 20th century was capped off in 2012 with the discovery of the Higgs boson.
Now we do this work here at Oxford through making measurements of the universe, and we're joined by colleagues around the world in doing so.
And as we made those measurements, what we've discovered is that there's much more about this universe than is in our standard model.
And to paraphrase Newton, what we know today is just the drop in.
What there is to know is an ocean. That's our job on the generations in front of us to explore that ocean.
And so we do that here and around the world, building very large and sophisticated instruments and analysing the data that they
take on this day to look for evidence of what is the true nature of your retreat.
What do we really mean by cool? What do we mean by an electron?
We don't understand these most basic things. We also don't understand why galaxies are held together by dark matter.
What it is we try to find both deep under the ground and also by crazy.
And we hope that the Large Hadron Collider will so good telescopes that map the cosmos and
try to understand the mysterious energy that drives galaxies apart and ever accelerating.
Right. And all of that work is made possible by the taxpayers of the world.
And in the UK we are especially privileged to receive great support from the UK
taxpayer on the wisdom of governments that decide to invest that money in pure science.
But at the same time,
we are mindful of the fact that many international partners around the globe enjoy greater support for the science that we do here in the UK.
In fact, the UK is eighth out of eight in the G8 in terms of fraction of GDP that's devoted to science.
One of the reasons why we've been successful at Oxford is because in addition to that important and essential support of the taxpayer,
they've also benefited from the support of foresight about benefactors.
And I would like to give you one example. Later today, we're going to see an exhibition of the Sudbury Neutrino Observatory experiment upstairs.
When the next round was built, Oxford played a unique and leading role from the only UK university on the experiment.
When you go into that exhibition, you're going to see 20.
Fill theses of Oxford from students that help to make that experiment work, along with the work of engineers and scientists and academics.
And they play to the crucial roles. One of the students played an especially important role in an analysis technique
that enabled the evidence for neutrino oscillations to be established.
And this led to the conclusion that neutrinos have mass, and this led to the Nobel Prize for physics in 2015.
And that students name was Jingsheng. And he was only here because of the wisdom of private manufacturers that supported these different studies.
Now, one of my colleagues today leads the new version of snow.
Snow Plus in his head at the moment is actually going to get a statement that
will tell you and all my colleagues who tell you how much they need students.
But the science funding falls. The number of students that the UK government provide across all of science is far less than we need.
Fortunately, last year we had wonderful news that one of an anonymous donor from particle physics was going to create the new student in perpetuity.
The difference being that John has launched now a programme to raise funds for the Oxford Endowment for graduate students,
which could expand that over the next five years to raise sufficient funding to support 25 students at any given time.
And what those students would earn is going to go off from that experience and explore the future, the future, that future of particle physics.
And they will perhaps one day win another Nobel Prize or two.
And that's why we've been glad to do a move, as they are here today, to tell us about that remarkable future that particle physics has.
So, John, as you know, is the director of the Directorate General.
Yes, that's what it says on the business card advert.
But as you probably also know, until very recently,
John was the chief executive of the Science and Technology Facilities Council of the United Kingdom,
which is responsible for supporting and glider and particle physics and nuclear physics
and astronomy and large science facilities and national laboratories in this country.
And John has been here before. He started out as an undergraduate at Cambridge.
He then had the other faces, the other face, and decided to take his dphil here.
And one of the people that interviewed him on the day he decided whether would accept him or not is sitting right behind Plan B.
It's no, it's not a wise, wise decision.
I'm going to tell you what he was telling me about your Internet. Ask me about any catch he got.
He managed somehow to get through the internet in about three or four days later, he managed somehow or other.
It actually got to be felt as he went off to the United States with a [INAUDIBLE] of a reputation and became the leader of the D0 experiment.
Fermilab, Tevatron. One of the most important experiments prior to the LHC is the one that discovered the CPU, for example.
And then he went on to advise the U.S. government through the U.S. Department of Energy, the first particle physics in the United States.
And then in 2005, he came back to the UK to become the head of the particle physics department of the Steps,
as well as the amplitude laboratory after several years in that role.
But I realised how talented this guy was. A mechanical business was just too small for him.
I'd say it's become a director of programs in science.
Yes, yes. And then in 2011, he became the chief executive of C and a guy did a very remarkable and very
successfully until a few months ago when we lost to the Europeans collection source.
Now, John, of course, is sought for his mission around the globe.
And so he serves and advises in many capacities, including CERN, Cultural Board of Fermilab and the Board of the Square Kilometre Right Telescope.
He's also chairs the European Strategy Forum and Research Infrastructure and plays a role in
the expert group on cost management and road control large facility infrastructure for Europe.
And he serves on many boards for his sage wisdom and to those kinds of home votes association and what remarkably, the human brain project.
Yes, it's saying any more. I'm going to tell you about the remarkable future of particle physics.
Thank you, John. Thank you. Yeah, I'll happily tell you about the Human Brain project over lunch,
because that's an example of, you know, particle physics, knows how to do big projects.
Not all fields of science do and excellent science there.
And really the management wasn't particularly good.
So let's start by looking back because I'm I've been asked to talk about the future of this field.
The future is defined by recent discoveries because those have set the direction in ways that were not the case five years ago.
And when we lay out the future today, it's not the presentation that would have been given a few years back.
That's a sign of a dynamic field, and that's a very good thing.
But it means that we we also have this paradox that while we know more, we actually know less about what we know than we thought we would.
And again, all signs of a dynamic field. Now, first of all, I should say I had no idea what the target audience would be.
And I still don't quite, because I know that I've I know some of you are practising researchers in this area.
Some of you are practising researchers in other areas. Some of you look more like undergraduates or graduate students.
Some of you are alumni who have gone off to do other things.
So I've really tried to pitch at that latter group much more.
Those who have an interest in physics, a knowledge of physics, but who may not be up to speed with it.
And so for that reason, there are very few equations here, lots of pictures and some snide comments from the presenter,
which is the real reason they put me on advisory committees. I think provide a little entertainment.
So the big thing that happened in the last five years for particle physics was the discovery of the Higgs boson.
As Ian already said, I had, I should say he pretty much summarised my talk in his introduction so we could stop that.
But I think the visual materials are too little.
So this was the culmination of decades of work and the proving correct of a theoretical supposition which had first been made in the mid 1960s.
So the the theoretical framework that Peter Higgs put together was then incorporated in a larger set
of mathematical models and equations that we came to call the standard model of particle physics.
And that was, as Ian said, successfully tested generations of experiments in the United States and at CERN to extraordinarily high precision.
But this last piece of the puzzle, the Higgs boson, had never directly been observed.
So there was a lot of indirect reasons why it would be.
Strongly believed to be that.
And that led to a high priority being placed on building the experiments and facilities necessary to see if it was indeed there.
Because even if it was, if it were not to be found with the properties that Mr. Higgs had predicted, that would have itself been a major discovery.
In fact, while we would have struggled to explain that to the public and politicians,
it would have been a far more interesting outcome than what did in fact turn out to be the case,
which was we discovered they discovered a particle with the properties almost exactly
agreeing with those that had been predicted in the Higgs theory five decades earlier,
which when you think about it,
it's an absolutely amazing accomplishment for the the theoretical basis on which this field sits to have sufficient precision
from the measurements and sufficient confidence in the set of equations that you can spend substantial number of billions,
work for many decades and be vindicated by finding exactly what you had predicted.
Almost too good to be true. But it is true, and as you can see, made the front pages of the general press, as you will remember,
if you were around at that time and even Brian Cox is in awe, it doesn't happen very often, does it?
So so here is the man. And of course, he went on to receive the Nobel Prize, along with some collaborators there and.
The Higgs is part. This is the only equation that appears at the top.
The Higgs is the missing piece. Then, in this structure, which is the Lagrangian of the Standard Model, a very compact notation.
If you go to Wikipedia, you will find the full equation laid out.
It doesn't fit on your screen when you scroll through it, not just on a phone screen, but a laptop screen.
Each of the the bits of notation here actually expands into many, many terms that describes the interaction of the electrons,
the neutrinos, the up and down quarks, the bottom and strange quarks,
the top quarks, all of the components of of matter, the forces that mediate their interactions,
the gluons with the strong force, the weak interaction with the W and Z and the Higgs.
And the Higgs is there for mathematical consistency in this theory,
but it's also there because without it you wouldn't be able to construct something which gave
mass to to the W and Z and created a slower rate of radioactive decay and so on and so on.
So there was a lot of reason to believe that this was probably true.
But we are experimentalists at heart and we want to test and oh sorry.
I should just remember the Higgs.
The argument for why the Higgs was important was something that led to the construction of the Large Hadron Collider at CERN and
what motivated the building of 26 kilometre particle accelerator underground in the tunnel that had previously been used for LEP.
And at the time, in the 1980s when construction was being approved, we were confronted, as he had said,
with the need to sell this to politicians and in a shameless piece of arse licking it was,
it was presented to Mrs. Thatcher as the interaction of the Higgs is analogous, madam,
to what happens to you when you try to enter a room and you get mobbed by people.
So basically the role that the Higgs plays in less mathematical terms than John Ellis here, our colleague from from King's College.
By the way, this is the mathematical description. This is the layman's description.
The Higgs is responsible for mass of the elementary particles.
The reason why quarks,
electrons and so forth have masses is because they're interacting with the Higgs in the same way that in this this this layman's description,
Mrs. Thatcher is unable to travel smoothly through the room like a massless photon,
because she gets grabbed and slowed down by all the would be conservative MPC who want to talk to her.
I could pass smoothly through this crowd without being interacted with,
and that is what happens to massless particles like the photon or nearly massless ones like the neutrino.
They have weak interactions with the Higgs field.
Particles that interact strongly, gain drag as they pass through the universe, and that is what we call mass.
And then there's a separate question of what that has to do with gravity, and we'll come back to that later.
So this is more like what's actually happening. If an elementary particle travels through the universe,
it can travel in a way that has very little drag, like a marble rolling across the smooth floor.
And those are particles with low mass.
Or it can travel with a lot of interaction with the universe, a lot of interaction with the Higgs field that permeates the universe.
And that is what we call a massive particle. So we built we a Large Hadron Collider was built.
And you can see Peter Higgs standing here in a very small segment of this 26
kilometre tunnel under the French Swiss border regions just northwest of Geneva.
And in this accelerator, which is to his right there, particles are accelerated up to, you know,
very close to the speed of light, so that the total energy in the collisions is 13 trillion electron volts.
For those of you who who understand what that means,
particles are then brought into collision at two locations where two very large detector systems study the results of those interactions.
And this shows a computer reconstruction of one of those collisions in one of those detectors.
This is the Atlas experiment, and I managed to choose the one that Oxford is involved in with a certain amount of care.
And what happens is that the Higgs well, most of you, if you are here, did study some physics.
And so you will remember you will remember that when there is a quantum field like this,
Higgs energy, which we are postulating pervades the whole universe.
You can excite quantum states in that field.
So the the ground state is is filling the universe with a certain amount of energy.
And that's what interacts with all the particles and gives them mass.
If you put enough energy into that field, you can create the next quantum excitation.
And that's what we call the Higgs boson. So this is real quantum mechanics at work.
That excitation decays after about ten to the -20 4 seconds.
And what it decays into are normal long live particles and those.
Are entirely predicted within the framework of the standard model.
So if the Higgs is what you think it is, you know exactly what you should look for.
You don't see little Higgs is coming out saying hello. Here I am, you know, sticking their head through the curtains like that.
What you see are the decay products of this particle.
And the way you know that you have that extra thing being produced is that there is an excess of
objects with an inherent mass that you can reconstruct back to the thing that they decayed from.
And so that is what you are seeing here. This happens to be the invariant mass of pairs of photons.
So the Higgs is decaying in this particular event, this collision into two photons which were measured in the atlas detector.
And there is an excess that you can see above the smooth prediction that you would have if there were no Higgs.
And the mass at which that excess takes place is the mass that you infer.
The Higgs has the rate of particles, is the rate at which the Higgs is produced, and you can check whether it decays into other things as well.
And it does.
And all of those properties turn out to be exactly what you would expect, which is great news and the worst possible news at the same time,
because if it was not what you expected, you would have opened the door to an entirely new world.
If it is what you expect, you've completed a checklist.
And so that's where we are now. There remain many open questions which are continuing to be addressed at the experiments at the Large Hadron Collider.
So the first part of the future of high energy physics is continuing to explore this newcomer,
which has landed on our doorstep in the last four years, which appears to be exactly what Mr. Higgs told us was going to land on our doorstep.
But we should verify and tested every possible way. So is it actually the standard model Higgs basically summarises all of this.
Does that therefore mean it's responsible for the masses of all of the particles?
Well, one way to check that is if it does indeed interact with all of the particles it proportional to their mass,
you should see it decaying into each kind of particle proportional to the square of the mass.
And that's a very simple prediction, a very hard to test, but it's a testable prediction of the model.
Are there other Higgs bosons? Are there other heavier partners?
You could construct an extension to the standard model, which had four.
Higgs is not one, and there's nothing wrong with that.
It's not necessary. Nature may not do that. It is not necessary, but it would be consistent with all the mathematics so far.
So we need to test that the Higgs might not be an elementary particle.
You could create a quantum mechanical field with the properties of the Higgs from two smaller things stuck together,
just like the proton is made out of three stuck together just like the pion is made
from a cork in an antiquark the Higgs could be made from a thing in an anti thing,
and it could still have the quantum numbers that the Higgs has, and it could still behave the way that the Higgs does.
So that again is hard to test, but it's a possibility, not in the standard model.
The Higgs might be the first of a long list of new other particles, and that happens in extensions of the standard model.
For example, we'll talk in a little moment about supersymmetry, which is a very popular,
long cherished extension to the standard model by our theoretical colleagues, but which hasn't so far shown up in the experiments.
And then there are questions about the Higgs itself. How can a particle like this have such a low and finite mass?
Now its mass is actually quite high on the scale of the proton and the neutron.
But on the scale of the energy of of the universe, it is it is quite small.
And the reason that that's challenging is that because the Higgs interacts with everything,
there are very large quantum mechanical corrections to its own mass.
And just like any other particle, you need to to calculate all of the quantum mechanical corrections to any property.
And in the case of the Higgs, it's a divergent series. The perturbation theory doesn't stop and its mass could be infinite or zero.
We don't know what it is.
So the mass is the single unknown parameter in the standard model, and there's actually no reason why it should have a finite value.
There must be something else going on. And the Higgs is also a strange thing.
Unlike the electron and unlike the neutrino and unlike the top cork, the Higgs has a value.
The Higgs field has a value which fills the entire universe, fills this room,
not because there's lots of Higgs is passing through us from cosmic rays or anything,
just because there is energy in the space time associated with the field of the Higgs.
And it's actually way too much. It's like 10 to 120 times more than we think is in the flat universe that we happen to live in.
So that's a little bit of a problem. And we don't know, well, if the Higgs was the only thing,
the universe would have expanded so rapidly that we wouldn't be here or it would have collapsed into something the size of a grapefruit by now.
So again, there's something else going on in cosmology, and we already know there's a lot else going on in cosmology.
So our best models of why the universe is like it is have very rapid expansion in the early femtoseconds of the life of the universe,
which we call inflation. There appears to be something called dark energy, which is making the universe slowly expand faster.
And both of those phenomena have the same kind of properties that the Higgs field does.
That's an energy field that appears to permeate the universe with the same quantum numbers that Mr. Higgs this thing has.
But they don't appear on Jon Ellis's T-shirt.
There's no dark matter, no dark energy, no inflationary expansion here.
So we know that something else is happening along with the Higgs thing. And it seems to be it would be nice if it was in some way connected.
All right. Supersymmetry is the most popular theoretical prejudice.
Addressing that list of questions before the Higgs was found was that the Higgs was the first of a whole array of other new particles,
and that I'm going to refrain from showing you the list of particles that particle physicists always show you,
because you don't need to memorise how many quirks there are. You just need to know that if supersymmetry is true, this twice as many,
and the new ones have properties related to the existing ones, but they're heavier.
So we haven't seen them yet.
And they have different spins which which quantum mechanically makes them cancel out some of the corrections to the Higgs energy in a nice way.
The supersymmetry would also predict some very nice properties too, to tie up cosmology with particle physics,
and it would make the universe an easier place for theoretical people to.
Sorry, this is going to sound demeaning. It is easier to relate to string theory and fundamental calculations about trying to
tie together gravity with with with the particle physics that we know and understand.
And so it's quite likely that the universe is, in some sense supersymmetric,
but we have no idea if it's supersymmetric at the energy scales that we can explore with our current experiments.
And in fact, it seems not, though I'm going jumping out a little bit on a limb here,
because so far we haven't found any evidence of any other Higgs or any of these other supersymmetric particles,
even though we can predict their properties relatively precisely.
So five years ago, if you'd asked people what you will, will you have found by now at the LHC,
most of our theoretical colleagues would have said a Higgs, maybe not the standard model Higgs plus one or two of these supersymmetric particles.
That would give us some indication that there's a bunch more going on.
We found a Higgs and we haven't found any of this other stuff. So what can you do?
Well, you can make the best of the tools you've got and continue to enhance their power and their capability to explore.
Because as the LHC collects more data, we are sensitive to rarer and rarer phenomena,
which means we're probing higher and higher mass scales for these new particles that may be predicted beyond the standard model.
We're also looking at smaller and smaller deviations of the Higgs from the properties that the standard model would predict.
So there is a rolling program grading the Large Hadron Collider.
So the Higgs was discovered using the data from 2012, and that was sufficient to discover the Higgs.
The energy was then upgraded and the run that we have that we've just taken this year was taken at higher energy.
And that's produced greater opportunities to test what is going on with greater precision.
But unfortunately, it hasn't yielded any new discoveries.
The LHC will be upgraded again in the long shutdown in a couple of years time and will run at a higher in collision rate for a number of years.
It will then be given a much more major upgrade at the end of this decade, which will enable it to operate for ten more years.
And you notice we haven't even put an end date on here.
So it will run into the 2030s and collect data sets which are of the order of 100 times larger than currently exists.
So that's sufficient to make really insightful discoveries beyond what we currently have.
If nature has given anything that can be produced at the LHC, if nature has not,
we'll be able to measure the properties of the Higgs with really quite surprising precision in this very large dataset.
Now, this is not simply a question of turning up the power and and dialling up the energy.
The machine will have to be substantially rebuilt.
It's 26 kilometres long and at least one kilometre of that will be ripped out and replaced towards the the the long shutdown here in the 2020s.
And it's shown in red on this and the schema,
the technology that's needed because most people in this room are probably techno geeks at some level is higher
field magnets which will enable the CERN accelerator people to focus the beam more strongly at the collision points.
And that increases the probability that the two co rotating counter-rotating beams collide
head on and therefore increases the collision rate and you get more collisions out.
In order to do that, you need higher field magnets in the collision regions close to where the experiments are.
And that means going beyond the current kind of magnets which are made of a niobium titanium alloy, which I think may have been invented in this.
Building or across the road, there are two new materials Niobium Tin, which are fiendishly hard to work with,
with cryo heat treatment and all sorts of difficulties putting together, but enable you to build much higher magnetic fields.
And that focuses the be more and gets higher collision rate and that will enable the LHC to continue to be a frontline facility into the 2030.
So this is an international development project.
This magnet is actually sitting at Berkeley in California and there are some UK contributions to this as well.
So the LHC will continue to be a frontline tool and will continue to be the Higgs factory that we can
depend on to make millions of these particles and enable us to study their properties at the percent level.
But if you really want to become a precision measurer of Higgs, you may wish for a cleaner environment than the Large Hadron Collider produces.
Because you remember that collision that I showed you?
There was quite a spray of other particles coming out of the collision point, along with the things that came from the decay of the Higgs.
And that's inherent when you collide. Protons head on. There's lots of other stuff in the proton.
They produce lots of other particles, some of them low energy, which are easy to remove,
and some of them are higher energy, which can confuse what you're measuring.
So for a a long time, scientists have been thinking about what you might do beyond the LHC.
You can continue the evolutionary path of Large Hadron Collider cars, and you could build a larger Hadron Collider.
And this is a deliberately sketchy attempt to show how that might fit in the region around CERN.
In the Geneva region, you can see the LHC shown there.
So this is an 80 to 100 kilometre tunnel and some preliminary engineering studies,
geological studies, geotechnical studies have been done on this such a tunnel and it could be built.
Unfortunately, you also get some sense of what it would cost because the Swiss know what tunnelling costs and it's not a small number.
So open your chequebooks, please, on leaving. But this would enable you to study in detail.
Not just the Higgs, but to produce pairs of Higgs is to see how it interacts with itself and any new particles that are just coming in to view.
When the upgraded Large Hadron Collider is running at the far right of that previous plot would be much,
much more copiously produced as this graph tries to show.
So hundred times gain, for example, for heavy particles compared with the LHC.
We do know that this is not a cheap and easy thing to do,
so it's something that would be unlikely to happen without some very strong motivation behind it.
But technologically, it's intriguing to see how you would build such a thing.
And this is by saying little graph about magnets. To do this, you would need even the higher field magnets unit.
The 11 Tesla dipoles that would be required for the LHC upgrade are the first step here, but we need something like 20.
Otherwise you have to build a two or 300 kilometre tunnel and that becomes prohibitively expensive.
And that means going to high temperature superconductors, non-metallic conductors in magnets.
The costs are 5 to 10 times higher right now, so those need to be pushed down.
But if you could build 20 types on magnets,
it opens up the intriguing possibility that you might install those in the Large Hadron Collider tunnel, the existing location,
and that would enable you to get to significantly higher energies relatively cheaply
compared with the cost of building 100 kilometres of of subway tunnel around Geneva.
So R&D on this kind of high field magnet is something that would obviously benefit lots of other areas of science beyond particle physics.
And it's a it's something that I think should be a is a priority for the future.
Now, as I said, you might want to study the Higgs in more precision,
in which case you don't need higher energies, but you need different kinds of beams.
So for a long while, scientists have thought about building a precision collider to take a beam of electrons in a beam of positrons and bring
them head on into collision with sufficiently fine focus nanometre sized beams that you can collide and produce Higgs.
In this case, it would be producing a Higgs with a Z technically, but that would give you a very clean sample of lots of Higgs,
and this is a fairly well worked out design for a 30 kilometre long straight accelerator that will collide
electrons and positrons head on with an energy optimised to produce lots of Higgs is what's not to like.
Well, a lot of R&D has been done on such a thing.
Several hundred millions have been spent to develop the technology.
The key technology for this is the accelerator.
So in contrast to a circular, circular collider where you're trying to bend the beams in a circle here,
you just want to get them to the highest energy in the shortest possible distance.
And that uses superconducting radiofrequency accelerator like this.
So as the beam passes through, it gets a little kick of energy from each one of these cavities, which has a standing wave set up in it.
And that's a superconducting cavity.
So there's no dissipation of the energy, which is a very good thing to do, but it's a relatively expensive technology.
We are using it at SS. It's been used in other, other locations.
It works, but it is not as cheap as people had hoped when it was originally proposed.
So I've sort of I've chosen my words carefully there.
I haven't said too expensive, but it's certainly very expensive.
And one possibility is that such a machine might conceivably be built in Japan, or at least there are people in Japan who would like that to happen.
Now the Japanese government has other priorities like hosting the Olympic Games,
so it remains to be seen whether they would invest the huge amount of money that it would take to put a a major contribution in here.
But this is the the coordinator of the project meeting the Japanese prime minister.
So, you know, it's not it's not as if it doesn't have traction at government level.
The other possibility, which has come in from the east, is that this idea, if a linear collider turns out to be a little bit too expensive,
maybe you should consider a circular machine which can produce lots of Higgs.
And a few years ago people would have said, Well,
that's not a sensible thing to do because we know that the cost of circular accelerators is basically going to go up like the square of the energy.
Sorry, another equation I apologise. Whereas linear colliders should go up like the first power of the energy and therefore above some some point,
it should be cheaper to build a straight one than than a circle.
Well, it's turned out that the straight one is a I shall avoid words like fiendish but more expensive than thought.
So this has created interest then in China of all places,
for potentially a very large circular accelerator that could be built as an electron collider.
First, produce lots of Higgs boson and then later upgraded to do something like that.
Future Circular Collider at CERN.
Now this is a design study that's been pursued by the Chinese Academy of Sciences and the Institute of High Energy Physics.
They put in a proposal to the five year plan, which is apparently what you do,
and they got R&D money, which is good, but it's not a huge chunk of R&D money.
So there's a few lessons for here. We often look at China and think, as soon as someone in China says Do this,
it happens because the Politburo signs up and they have unlimited billions.
It's more complex than that. I'm watching this project from outside is surprisingly revelatory about decision making processes in China,
which are not as politicised as you might think. There's a scientific review process in the academy.
There are scientists who speak out against the project because it would be too expensive.
There are others who say, No, we really need to do it to put China on the map for fundamental research.
All the same arguments. It's just that they weren't elected. They make all the same arguments.
In fact, they're probably more intelligently made because the Politburo is full of engineers.
So. So this may well happen.
It won't happen as quickly as they would like and even as quickly as they would like.
It doesn't happen that quickly. The limits in China to doing things are not necessarily having the money because their political system
doesn't have quite the same links between government budgets and and know balanced budgets and so forth.
But their expertise, there aren't enough accelerator scientists in China to do this.
There aren't enough particle physicists in China to do this. There aren't enough technical people to design this.
So those are what slows down their delivery of big telescope projects.
That delivery of aspiration, neutron source, the delivery of the Shanghai Synchrotron,
and those would be squared or cubed in difficulty for something like this.
So if this is to happen, it will have to happen as an international project.
And that's a very interesting possibility for the 2020s.
For example, if we if it if it does gain traction. We shall see.
Now there's a ritual slide that has to be shown at this point,
which is to point out that all of the particle accelerators that I've talked about so far go back to the 1950s or sixties.
They're using radio frequency energy to accelerate charged particles in an electromagnetic cavity.
You can accelerate particles using light in a plasma cavity, or you can use a laser beam to excite very small cavities in ways that,
you know, don't depend on on basically Second World War vacuum tube technology, which is still what we're using.
And so if you visit Berkeley, Wim Lehman's will show you.
[INAUDIBLE] say this is a particle accelerator. It fits in the palm of your hand.
You can get a GeV of energy out to that. Well, you know, he says he takes 100 metres of accelerator to get a GeV of energy.
Isn't that great? And then you go upstairs and you find he's got 100 metres of laser.
So it's not so obvious to me that this is the right way to go.
It may well be. It does have a little bit of the nuclear fusion into it that it's always a few decades into the future.
So the future Circular Collider that's being sketched out for CERN does not depend on this.
The IOC does not depend on this. If somebody can make this work. Let's build an x ray light source like diamond.
But it would fit in this room. And that would really demonstrate that the technology has arrived.
And there's a lot more places in the world that would give you money for an x ray light source, especially if it fit within this room.
So so I think this is technology with lots of applications, but it just may not be forefront particle physics technology yet.
Now, I've talked a lot about Higgs and supersymmetry, and I've also admitted that we haven't found anything beyond the Higgs.
So it's quite possible that we are, as the proverb says, in a dark room, searching for a black cat that isn't there.
We have to. It's a long way to go from absence of evidence to evidence of absence.
And we're not there yet. But after a couple of decades of running a the Large Hadron Collider and not finding anything,
I think most physicists will be in a position to say in ten years time, maybe this other stuff really isn't there.
It's not just that a little bit higher energy or a little bit rarer to produce than we had thought.
And so that means we should also look for the other things that have come along and surprised us in the last few years.
The Higgs is clearly the pillar on which particle physics is based right now, and the Large Hadron Collider is the centrepiece of that program.
But it mustn't be the whole program because in the end there may not be a cat in the dark room.
Let me just take a little aside into metaphysics here, because if there is no cat in the dark room, if the Higgs is all there is,
we haven't solved those problems about why is its mass finite and what does it have to do with the universe.
It may be that we discover some other things through other routes,
but there is the rather scary possibility that we just live in a universe which is technically speaking, fine tuned.
And that means that the coupling constants of certain things just happen to cancel each other out.
And if you want to believe in God, you could believe that God set the world up this way so that that works.
Because if it was not set up that way, like I said, we'd be living in a universe the size of a grapefruit or no universe at all.
So for our universe to exist, it appears that there either has to be physics that we don't know about to make the corrections balance,
or there has to be some fiendishly precise one in 10 to 120 fine tuning between the various coupling constants so that the the
curling up of spacetime due to the Higgs is exactly cancelled by a cosmological constant of equal and opposite magnitude,
for example. That's not a particularly attractive proposition,
but it may be that there is some physics behind that because some of the string theories which attempt to describe the fundamental
basis of the entire universe and why a universe exists and how it could have expanded so rapidly when it was very young,
predict that there is, in fact an almost infinite number of universes with randomly selected coupling constants and and fundamental forces in them,
so that it could just be that we are in one of an infinite number of universes and of course
we're in the one where the coupling constants are fine tuned because in all the others,
the typical universe, there is no life, there is no stars, there are no planets, there's no quarks, there's no W boson, there's just nothing at all.
So that's depressing because it's fundamentally untestable, I think.
I'm not sure this is science. There might be ways you could verify this was true, because if the number of universes isn't completely infinite,
the amount of fine tuning shouldn't be arbitrarily large. But it is an interesting possibility.
And you will hear talks. You can have one next year about the string, the multiverse, and it will blow your mind.
But in the end, it's not science at this point. But that may well be where we are if we're in a back room without a.
So I don't like that outcome, so I don't like the fine tuning. So let's try and do some science instead.
So the Higgs was the last piece of 20th century particle physics in some profound sense.
It completed a line of inquiry that came from Feynman and quantum electrodynamics and
Renormalisation theory and trying to understand how to make quantum mechanics calculable.
In the 1940s, mathematical consistency, normalised ability, inherent self consistency among the equations you don't want divergences.
In fact, that's what led to the invention of quantum mechanics to solve divergences in classical mechanics.
So the Higgs draws a line under that, but it doesn't tell you anything else.
We haven't found anything else associated with it, at least so far.
So there are no more guaranteed discoveries.
The Higgs was a discovery of whether it existed or not, because the absence of a Higgs was it would have been a bigger discovery than the presence.
But there are no more, and many key questions remain to be answered. So sorry to all theoretical colleagues.
Your guidance is always welcome, but at this point we need to find some more data and some more experiments that we can do.
And that means we need to look outside the realm of the LHC.
And so I'll briefly cover a couple of areas where we are looking and where Oxford
is looking that we have discovered things that don't fit on John Ellis's T-shirt.
And that's that's what I mean by physics outside the standard model. So the first one of these is neutrinos.
Now neutrinos. The neutrino was postulated in the 1930s by Pauli as a product of radioactivity to decay,
along with the electron to maintain what looked like a violation of the
conservation of energy when a radioactive nucleus decayed through beta radiation.
The electron carries off some of the energy, but not all of it.
And you could either assume that energy conservation was violated in quantum mechanics, and that was a serious possibility at that time,
because quantum mechanics wasn't understood at the level that it was and partly pointed out, no,
you can maintain kinematics and energy conservation and momentum conservation if you propose the existence of a massless and in his view,
not interacting particle that is also produced along with the electron is not totally non interacting, otherwise we wouldn't be talking about it.
It turns out the since it is produced in a decay, it can be captured in the inverse reaction to that decay.
And indeed it is. So we know neutrinos exist and they were directly discovered in the 1950s and we can produce them and understand their properties.
It turns out relatively recently, as you will see upstairs from the snow experiment, that neutrinos are not such simple things as Pauli.
And we thought there are different kinds of them.
And when they travel over long distances,
much longer than the distances within a laboratory or within your experiment from the beta radiator to the detector,
when that's hundreds of kilometres of travel, the three kinds of neutrinos undergo a quantum mechanical oscillation from one kind to another.
And what you make isn't what you get.
You leave Geneva with Swiss francs in your pocket and you arrive in London and they've turned into a mixture of pounds and Danish krona.
And in the macro world, that doesn't work. Well, you do what you said it did for you once.
But in the quantum mechanical world, that happens because the mass eigen states are not the same as the flavour eigen states.
And if you don't understand what I just said, don't worry. If you do, that's the the most concise explanation.
So this is of interest not just because it's physics that doesn't fit on John Ellis's T-shirt.
And it might point somewhere,
but also because the oscillations between these three kinds of neutrinos may in principle have a large asymmetry between matter and antimatter.
And that is a little bit of a holy grail for scientists,
because we know that our universe is largely full of matter, or at least the close by universe is full of matter.
And we don't see any gamma radiation from distant sources,
which would imply that there's any annihilation between matter and anti-matter going on anywhere else in the universe.
So while we don't know for sure, it looks as if the matter in the universe is matter and not an equal mix of matter and antimatter.
But in any process, like the Big Bang, one should produce equal amounts of matter and antimatter.
And therefore something has happened to violate this symmetry either in the production or
in the subsequent interaction and decay and neutrinos might be a link to such things,
though it's all very sketchy at this point, and nobody can quite explain in total detail how that could lead to a universe with with stuff in it,
and not an equal mixture of stuff and anti stuff. Nonetheless, it's an extremely intriguing possibility.
So just as there are large plans to explore the Higgs,
there are large plans to explore the properties of neutrinos over the kind of distances that allow this oscillation from one kind of neutrino to
another to fully play out and would allow the the differences between their interaction with matter and anti-matter to become fully apparent.
And to do that, you need to produce an intense beam of neutrinos. Let it travel through the earth.
Doesn't matter. You don't need to dig a tunnel. They will not interact significantly, sufficiently,
significantly to lose the intensity that you need and detect the neutrinos at a location of your choosing.
And so what is proposed in the United States is to start at Fermilab, where just to the northwest of Chicago here,
where the neutrinos will be produced and they will be shot downwards at a certain angle.
Because if you think about it, the earth is a sphere.
And therefore, in order to to reach South Dakota, they have to be directed downwards a little bit.
They will travel under the earth for about a thousand kilometres and emerge, will not emerge.
Intersect a mine. The Homestake Gold mine, which is no longer a gold mine, has been.
Care taken by the state of South Dakota as a future physics laboratory.
And in that location there will be constructed if money is voted by Congress,
a very large set of caverns which are shown here about a mile underground,
which will include very large tanks with something like 50,000 tons of liquid argon.
And the beam of neutrinos will be coming this way. And every now and then,
one in a billion or something of those neutrinos will interact with an outgoing atom in these tanks and will produce ionisation,
and the ionisation will be drifted onto cathodes. And from that will scientists will be able to infer what kind of neutrinos have arrived,
the rate at which they've arrived, and the energy that they are carrying. Now, this looks all very clinical, doesn't it?
It looks like like you could just, you know, draw that.
But in actual fact, a mile underground in a gold mine isn't clinical.
It's it's a dangerous big environment. And the plan here is to dig out 100,000 tons of this rock in a few years on a conveyor
belt out the side of that mountain and dump it in a what used to be a settling pond,
for it is a god awfully polluted place.
So there's not too much worry as there might be around here at filling up a gravel pit with 100,000 tons of rock.
And that cavern has to be excavated safely, of course, and then it will be filled with detectors.
And so this is a prototype of one of those much smaller than what will eventually be built.
You can see copper wire planes onto which the charge will be collected.
And this is a neutrino interaction here. Neutrinos come in, hit a nucleus and produced ionising radiation,
which is how you detect if there is a similar project under discussion slash close to approval in Japan.
And so what we are seeing now is something like a global coordination of particle physics projects
appearing where both Asia and North America are contributing to a Large Hadron Collider at CERN.
And there are going to be contributions from universities and laboratories in Europe to both of these programs.
So that will be a rather nice international complementarity rather than everybody trying to do exactly the same thing.
And I should say there are good science reasons why you would want both this and this.
Now, the other place where new stuff has happened is the cosmos astroparticle physics or particle astrophysics,
or the discovery of hints about the fundamental equations of the universe,
not from experiments in colliders, but from the the signals that come from very distant stars and galaxies,
or from high energy particles impinging on the earth from from distant events.
So this is the Planck satellite, which was launched by the European Space Agency,
superimposed on a map of the cosmic microwave background radiation in the universe.
So that's the surface of our scattering when photons were able to propagate freely after about one hour when the universe was 100,000 years old.
Something like that. 300,000 years. Okay, order of magnitude estimates.
So that is as far back in time as one can see.
And it is not uniform as the colour indication here is supposed to.
It would be uniform if you showed it in true temperature.
That is the temperature of universe and the small fluctuations in that are what
seeded and grew to form the galaxies and large scale structure that we now see.
And you can look at the multiple moments, odia technical word again, you can look at the angular distribution of those fluctuations.
And if there are a lot of very short wavelength fluctuations, you'll get a lot of very large multiplying numbers here.
If there's if there is a dipole, big dipole fluctuation, you'll get something at the peak of two and you see there is a dipole.
And that's to do with the earth moving through this field.
But the exact structure to this is a predictable thing.
And what it tells you is that the universe is full of stuff that isn't protons, neutrons or again on John Ellis's t shirt.
And we capture the behaviour of that stuff by dividing it into two categories the stuff which looks like particles of matter,
and we call that dark matter, it appears to be neutral, weakly interacting, clumpy, so not relativistic.
But beyond that we don't know a huge amount about it.
And it appears that from our astrology, astronomy, astrophysics, colleagues, most galaxies, probably including ours, have a lot of this stuff in them.
And it may well be that the stars, planets and stuff that's made of material like us is just a little dressing on top of a dark matter structure,
which is really what we're seeing.
The other 90 though, sorry, the other 70% of the universe or the mass energy in the universe appears to be something much more mysterious,
which we call dark energy. And that. Is a quantum mechanical field which appeals appears to pervade the universe with a sort of expansionism,
an expanding attention to it, driving the universe to grow.
And that is so. So you can have a seminar where they come up with a long list of plausible candidates for what dark matter might be.
And then the next slide will be plausible candidates for what dark energy might be, and it's usually empty.
So the combination of these two shouldn't really be lumped together.
I think dark matter is something that we can understand as eventually it will have to fit on John Ellison's t shirt.
Dark energy may be something much more to do with Do we understand Einstein in relativity at the level that we think we do?
Is there a cosmological constant? There are experiments going on to see if there's been any change over the
lifetime of the universe to the amount of dark energy that there appears to be,
because that could tell us rather interesting things about whether it is indeed
a property of space time or whether it's something filling the universe, but not a subject for today, except to note that the normal part of this,
the dark matter part of this is something we can and should look for in experiments here.
And indeed, snow is part of the the toolkit to do that.
So I'm just going to show you a project which is relatively new in which the UK is getting involved in called like Zeppelin.
It happens to be going to be located in this same location in South Dakota and the excavation for Elzey has already taken place.
And as you can see, it's a cavern about the size of this lecture theatre.
Maybe double the height which has been blasted out to the rock is the mining
people like this rock is how it stands up without needing to be supported.
But it is difficult to excavate in and in a few years time that cavern will be filled.
This is approximately to scale.
Cavern will be filled with this experiment which will place a very large vessel of liquid xenon in the middle and surround it with photo
multiplier tubes that will detect flashes of scintillation light and drift the charge on to enable you to collect the charge as well.
So this will be as the earth drifts around the sun or and as the solar system drifts around the centre of our galaxy,
we will be slowly passing through a cloud of dark matter, which is part of the galaxy, like the stars and and gas clouds and everything else.
And so this experiment should just slowly pick up dark matter particles as the earth moves through them, a wind of dark matter.
And every time it does, every time one of them happens to interact elastically with a xenon nucleus,
we should see a little flash of scintillation light in this detector. So what gives you the sensitivity here is the very large volume.
This technology has been used on a smaller scale and we know it works.
We know that dark matter exists. But this is a little bit of a shot in the dark, if you pardon the pun,
because we don't know for sure that the mass of the particles is such that they will be detected in in this experiment.
And I should link back to the Superman logo here, because in supersymmetric models,
one of the new particles that is predicted is a perfect candidate to be this dark matter that
with about the right density and about the right properties that we'd expect in the universe.
So it would be really, really neat if that was true.
But the universe doesn't make things happen just because they'd be really, really neat for a bunch of people in the 21st century.
So it may well have been done differently, but it would be neat if that turned out to be the case.
We should also just say another thing which is new, but which I'm not going to say any much more about is new.
Ways of looking at the universe are also opening up so early.
About a year ago,
you will have heard of the discovery of gravitational waves from a collision between two black holes in a galaxy about 1.3 billion light years away.
This is a computer simulation of the waves of gravitational energy that would radiate out from such a collision.
And the little traces here show what was actually measured in precision detectors located
in the United States when that wave of gravitational disturbance went through the earth.
So, you know, real life disturbance in the force from from Star Wars,
but picked up with a laser interferometer that can measure pico metre separations in two mirrors that are a couple of kilometres apart.
So this is a new way that we will be able to look at the universe and we will be able to start doing astronomy
with gravitational waves in the sense that we can pinpoint the direction that these things came from.
When some additional instrumentation comes online in a couple of years time,
you'll be able to triangulate the direction that the waves are coming from, and that will be interesting and potentially important.
So how much time do I have in you have about 5 minutes. Right.
So. I'm going to zip very, very quickly through some of those points you made about the need to explain and justify what we are doing.
The broader context in which we operate. So one of the reasons I got interested in science policy was the observation that this can go wrong.
This was a beautiful project in Texas, the superconducting supercollider, which would have,
if completed, discovered the Higgs about ten years before CERN eventually did.
But it didn't discover the Higgs because it's now filled in and was cancelled about three years after after excavation started.
So, you know, when you interact with with government, you have to understand why they want to support science.
And they do recognise, I think even at really relatively high levels, that our prosperity depends upon science.
There's a market failure because most business likes to do relatively incremental improvements.
What we have to do then as science is do stuff that isn't incremental, that's potentially transformative.
I should say there have been some shining examples in the past of businesses that did support transformative R&D.
Bell Labs with the transistor, for example,
the invention of the laser and maybe Google now with artificial intelligence is doing stuff that they don't see market value for.
But the pay offs are long term and uncertain.
So here's a scientist doing science, and what she wants to do most of the time is understand the universe.
And I've just talked for an hour about that. We take money to do that.
And money comes from governments, and I'm not sure whether any will come from this particular one.
We shall see. Government tends to be motivated at some level by understanding the universe because they are usually educated people,
usually more educated than we give them credit for.
But they really like the technological innovation and skills that feels like particle physics can deliver because we can do things that push science.
Sorry, but we can do science that pushes technology.
Big science in astronomy and nuclear physics has the same thing.
So why don't you know if it's if science delivers the solutions to big challenges,
why shouldn't we direct all of our resources to work on big challenges like renewable energy?
And the answer is that doesn't excite young people in the same way that particle physics does.
Apologies to anyone in the audience who is now working on renewable energy.
But we have good evidence from from surveys of students that fundamental research attracts
young people into science in much greater numbers and drives technological innovation.
So how much does it days? He always says, Oh, John, you are not selling the stake.
You are selling the sizzle. This was a legendary advertising campaign in the United States, and I guess the sixties were selling the spinoffs.
And so when the Higgs was discovered, CFC supported an exhibition at the Science Museum and made sure that this guy was invited.
George Osborne, who was, of course, the source of money.
At that point, we made sure that the Large Hadron Collider was plastered over the front of the BIS office building in London,
so the civil servants who were paying for this would see that their money had gone on, something they could be proud of.
And we made sure that it was highlighted by foreign direct investment programmes.
There's been a significant increase in the number of students studying physics in undergraduate courses,
not all entirely due to Brian Cox over the Large Hadron Collider, but.
But some of it is to do with the greater visibility that the physical sciences have had in the fundamental physics to do with the Higgs.
And I think that's something very important.
We should also remember that long before the Higgs was discovered, the tools that were needed to do so transformed all of our lives.
So Tim Berners-Lee, with his proposal for information management.
Vague but exciting as it was famously reviewed, went on to be the World Wide Web.
And, you know, you used it to find out how the traffic was coming here.
So we can't claim credit for the entire global economy as a spin off of particle physics,
but it has changed the entire global economy, and that's something that we should never stop talking about, albeit slightly humbly.
Another example, which you may not be so familiar with,
is that research into look at looking for radiation from black holes at the Commonwealth Science and Industry Research Organisation in Australia.
This is one of their radio telescopes led to patents which are incorporated in the wi fi chipset.
So CSIRO receives about $200 million a year in royalties from wi fi patents, which is pretty good as a demonstration that radio astronomy has,
you know, transformed the way that we communicate because there's a real monetary value associated with it.
And the fact that companies pay to use it shows the value in ways that are much more than hardware.
I once did a estimate of the impact of the Tevatron accelerator, where I had worked for for many years,
and we concluded on the back of an envelope that there was something like a ten times payoff
to US society from the investment that had gone into into this machine over its lifetime.
And one example of that, which comes back to the magnet technologies, the Tevatron was the first large scale installation of superconducting magnets.
It's a national engineering landmark in the United States because of that that led to is documented
that that led to the adoption of superconducting magnet technology by companies like GE.
For MRI scanners, the MRI industry is worth about $5 billion per year.
I forget if that's within the US or worldwide, but you shouldn't even think about that as the pay off.
You should think about the improved health outcomes that have come from the widespread use of these machines,
all the days of work that aren't taken and the longer life that's been contributed to society.
So I think I'm about to conclude the future of particle physics.
Well, the first message is that it's different than we thought it was a few years ago,
and that's great, because if it was the same, it wouldn't be the future.
It will be driven by experimental discoveries. The science goals behind those discoveries are clear.
We found the Higgs. We know we need to understand the properties of neutrinos in detail, and we know we need to explore these cosmic connections.
What's behind Darth Vader's helmet is the dark matter that seems to make up a lot of the universe connected to two models of equations or not.
A global strategy for the toolkit to do this is emerging.
It's anchored by the Large Hadron Collider.
There's been a huge investment in that machine, and it's still delivering front cross science with substantial upgrades.
And we know how to do that. We know the technologies that are needed a neutrino.
Program with long baseline experiments using particle accelerators to shoot beams of neutrinos at underground detectors,
which will enable us to explore whether this is to do with the matter.
Antimatter asymmetry in the universe, and I should say nothing at the LHC has pointed in that direction.
So it's really quite important that we we we follow up on this and it's also important
that we follow up on these astroparticle connections connecting the particle
physics done in accelerator laboratories with what we know about the universe
from astronomy and astrophysics and exploit new hints like gravitational waves.
New ways of looking at the universe that we sit in. And there is no shortage of ambitious ideas for the future.
As I've said, a typical issue there is getting the costs down to the affordable level.
And in many cases there's some technology R&D that we need to do anyway, which is well worth pursuing.
Challenges are technological but also political, and as Ian hinted at the beginning,
there are ways that people can help, not just those who might be in a position to to down student ships and so forth.
But all of you, in talking about the excitement and interest that this field has, the progress that it's making,
and the arguments that I've I've outlined about the value in terms of technology and skills to the economy.
So thank you all very much.