As the LHC has been
Working and running people are beginning to ask the question:
What comes next in the world of high-energy physics?
Should there be another Collider? And it's kind of become an issue for some people because,
The Large Hadron Collider, although it's doing fantastic science,
It's measuring quantities to amazingly high precision, if you think of it in terms of the discovery of new particles,
It's discovered one, which was the Higgs back in 2012.
BRADY: Which is what it was built for!
PROF: Exactly.
PETER HIGGS: Really an incredible thing that it happened in my lifetime.
PROF: But it's not found anything else.
It's not found any evidence of dark matter, which throws through the world of supersymmetry.
It's not found any evidence of more exotic things.
Perhaps like extra dimensions or other new particles.
It has demonstrated that we have effectively an interaction between the Higgs and the fermions,
a force acting there that we need to understand better,
because we can now probe that regime which we couldn't before.
But the question is, Do we build an even bigger Collider?
And it was brought to a forefront by the recent publication suggesting that
there might be what they call a future circular Collider based at CERN.
That's where the current Large Hadron Collider is.
The Large Hadron Collider is underground in a ring that's about 25 kilometers long.
The Future Circular Collider would be a ring that's a hundred kilometers long,
four times the length.
It would cost of order 10 to 20 billion pounds.
Naturally a question that we need to ask ourselves, both as physicists but also society,
Where do you want to invest these large amounts of money?
There was a particular article that, at least within the particle physics community,
was read a lot, by Sabine Hossenfelder, in which she said,
Although she accepted that probing fundamental physics through a particle accelerator
is the best microscope there is to do that, the fact that we've only made this one
Discovery and we don't have any great ideas as to what is coming next in terms of theory
Perhaps we should be deferring building
maybe not even building a future Collider until we have our theories firmly better established and
Then we can perhaps go ahead once we've said well
this is almost certainly to be be the way forward and that and therefore that will dictate the
form of any large Collider.
BRADY: Rather than kind of fumbling in the dark
PROF: I think that's a probably she would agree without that that the way that we if we
Go ahead right now. We are will be basing it on physics that we already know but more speculative physics about what's coming next
And so and it's a really important question to address for me personally
I think it's it's a it's there's not a clear-cut answer
I
Remember back in the 1980s when the Large Hadron Collider was being put forward and maybe even slightly earlier
People did think they knew what the solution was. They did think that
Dark matter would be found in what was known as WIMPs, weakly interacting massive particles. There was we talked about a wimp miracle and
There were natural candidates for this WIMPs, which were coming from supersymmetry
The Higgs mechanism had been suggested back in the 60s
and so there was a there was in some sense a well-defined path to go along and if I were in it
But the very first conference I ever went to in 1983
was at the Royal Society and Stephen Hawking gave a talk there in which he said we
Will know everything by the end of the century and it's all "N=8 super-gravity". He called it
It was called and turned out not to be the case
there was an example where we did think we knew where we were going and we the decision on the
LHC was made and you do need to make these many years in advance, you know the LHC came into operation in 2008
Right, 20 odd years nearly thirty years after the initial proposal the proposal for the future circular
Collider would have it starting in
2050 because you've got to build these things you've got to develop the technology
Ed, are you saying that the large hadron collider didn't end up
Discovering the thing it was built to discover? No it did. You're quite right
You said at the very beginning its primary goal was to discover the Higgs, but it had secondary goals
and there was a real feeling that it would probably be able to if it found the Higgs it would probably find the
these WIMP particles because there was
supersymmetric models which suggested that WIMP particles would be in the same sort of mass range as the Higgs. That wasn't the case
And that wasn't the case they have just not they're just not showing up. In fact, no new particles of showing up. So the
Argument for building the big circular Collider isn't there as strongly as it was for the LHC?
In the sense of having a whole series of particles that you think you're going to find
Yeah, as far as I can tell there's not, and in fact
It would be a case that we'd be building it partly in order to actually
use the upgraded LHC and of course the LHC itself still has many years left of its lifetime to go and
Be using it
Not only as a discovery machine to actually find new things that might might be there but also to as a high precision
Machine to help us
understand the standard model and in particular the Higgs and the interaction the Higgs has with fermions with the
Things that you and I are made of the quarks and the leptons so to help us understand those interactions much much better
because another way of finding new physics is to say here's my standard model prediction for some very
exotic process then I go and measure that exotic process and I find a difference and
the difference may only be in like the tenth decimal place
but if you are
Sure about the calculations that have gone into it and sure about the measurements then there's your probing your finding evidence of new physics
This is the detector and that's one reason why you would go for it
You know a much more powerful machine that can probe into these new areas
Smaller length scales higher energy where things might pop up. We just don't know. It's one of the
Frustrating things about this. There's two things that can go on here
You can build a new Collider to find a new particle and have some paradigm change
Yeah
Or you can build one to just like fine tuning and get a higher resolution and better pictures and then two different arguments
It feels like yeah, but in fine-tuning you looking for differences, right?
It's not a case of I mean, yes, that's what you're always probing for you with a wave physics works
Right as we basically we don't try to confirm models. We try to rule them out
That's kind of in our heads we try to find deviations and that's what would this fine-tuning. It would be rather than having, you know
Something smash you in the face. And so here I am, this brand new particle. Look at me. I've revolutionised things straight away
It's a much more subtle way of doing it. You're finding deviations from what the standard model would say and and and
Nature is can be like this it can it can hide
These new ingredients that make it very difficult to find and if we don't build something, we're not going to find them this way
Ed, I know it takes a lot of time to build these things,
but still, wouldn't it make more sense to wait for the next really paradigm
I think Sabine's got a very valid point here, but you know
But but the question also is at what stage?
In that process do you say AHA now it's time to build my new
You know
future circular collider
Because there is kind of two two aspects to it one. Is that the technology involved in the under theorist?
What do I know but I believe the technology involved in this is really complicated. Okay, you you they're always at the cutting edge
developing things
so what the LHC can do right today the back in the
1980s people no idea they'd be able to do it at the level that they can do it because
Technology is developed
one of the reasons they've been able to do it is that there was always a funding stream to help support the
superconducting magnets to help support the development of the
Accelerator technology the detector technology if you put that on hold right and said, okay
Let's just let the theories have a go now for a while until we come up with something
What are these people going to do? They're not going to hang around. They're not going to play say yeah, this is okay
Let's just there is take about five years. Let's go and do something else
They're going to leave and the subject and the runs the real risk. It is an expensive city
It's like Apollo they will leave and that's it. It'll be the end of it
And and okay, if you if you prepared to accept that so be it that that's the nature of it
there is one possible route through I
And I think Cerner are playing this
They're playing for two possible scenarios here
There's another one, which is that although they've come out with this future Collider circular Collider paper
And I personally think it's really exciting
they've also is sort of at the same time come up with it with another set of papers where they're looking at actually what it
Can we make use of what's around CERN at the moment to actually probe different types of physics, which would still be
looking at underlying fundamental physics of our universe but not
Requiring, you know?
Really high energy particle collisions? And this is motivated partly by the fact that we've not seen any evidence of dark matter
we've not seen these massive doubt matter particles and maybe
What what is actually going on in the universe?
these equivalent dark matter particles aren't very massive, they're maybe really light and
They don't interact very much with us in which cases having a big heavy Large
Hadron light Collider won't be the way to see them. We need more sophisticated
Ready-made
precisely-made detectors to pick up some of these lights particles like axions
specific axion detectors and so one possibility is to actually look at and for a set of
experiments
That could be based around CERN using the the accelerators
They've already gots and using some of the facilities they've already got so just bout better experiments under the existing ring
They use it. Yes, so they use up I'd bolts is a
thinking of it and
gently place
existing expect, you know, you use what you've got and then
lots of us
Go that was so exciting. And and of course you're building new things as well, but that's well. That's that's another possible and
So why ever said that I could imagine?
the community saying
Okay
Let's have this period where we go that route for a little while
Let's keep the R&D going for the for the big accelerators
But during that period we can be probing testing these these models of weak coupling regimes like dark matter particles
screening mechanisms, which could account for you know the fifth force that
Could be driving the accelerating universe
But meanwhile carry on with its R&D invest in the R&D for the future accelerators
And then hopefully some results will come out of these
New set of proposals or some theoretical developments will emerge which say yeah. This is the way we should be going and
Then you can sort of decide
Ok
Now we'll start the process on but there is always this risk back in the 80s people were absolutely certain
I think a pretty certain about that not absolutely but fairly certain that
WIMPs were the way forward and that supersymmetry was the way forward
There was no question to build the Large Hadron Collider after the large electron positron Collider
It was it was just the thing to do and it turned out not to be right
It's er it who knows? That's the
Excitement's of many ways of working in these kind of fields. What would you do, Ed? Because obviously you're biased
yeah, but you do live in a world where you are also like, hospitals and
potholes to be built, and your children are going out to the world that need infrastructure
How do you think the money should be spent so it's a lot of money and
I would spend it and I
because for a number of reasons one is
You know, it's not just the UK contributing to CERN. CERN has got 22 members
It's got I don't know eight affiliated members, you know, there's 30 countries here will all contribute
They'll contribute over many many years. Okay, it's not as if this is an immediate out-lay, so there's a
dispersion of the actual finance.
Of course hospitals need all the facilities they can but, you know particle physics live in hospitals
right
my you know my dear father who passed away when I went to the city hospital for him to have Radiology treatment.
On the wall, is this amazing plaque, I've tried to find an image of it that talks about the cyclotron
accelerator that they were using and
The and that's that was the particle physics of the forties thirties forties fifties that is now in medicine the MRI scanner that was invented
here at, here at Nottingham
Uses technology from the physics environment where there was
purely for research that is now been bedded in in hospitals all around the world medicine needs
Funding in its own, right?
Of course it does but it's had so much input from fundamental
ideas fundamental physics ideas for a start and chemistry and
radioisotopes that everywhere in medicine that to simply
Simply say yeah
we should be putting all of this into medicine for example is
Not the way to make the major breakthroughs that will help people in the future in medicine either
What makes us special what makes us special is our inquisitive nature. We want to know about the universe. We want to know about beautiful
pictures and admire them we want to know about what makes the universe tick.
And we should have the facilities to be able to invest in all of these