What Particles Remain to be Discovered?

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This is the BBC.

Hello, I'm Robin Inks.

And I'm Brian Cox.

And in a moment, you're going to be hearing me say, hello, I'm Robin Ins.

And I'm Brancox.

Because this is the longer version of the Infinite Monkey Cage.

This is the podcast version, which is normally somewhere between 12 and 17 minutes longer than that that is broadcast on Radio 4.

It's got all the bits that we couldn't fit in with Brian over explaining ideas of physics.

I do object to the use of the word longer, though, because that's obviously a frame-specific statement.

Yeah, we haven't got time to deal with that because even in the longer version, we can't have a longer intro.

Can we just let them listen?

I've got an idea.

Can we just have a podcast version of this intro to the podcast, which can be longer than the intro to the podcast?

And then we can have a podcast version of the podcast intro to the podcast.

I don't know what's going on.

Then we're going to have a podcast, podcast, podcast version of the podcast, and then it would do a podcast version.

Hello, I'm Robin Inse.

And I'm Brian Cox.

This is kind of Harold Pinter's version of the Internet Committee.

Since the last series, Brian and I have been on tour, genuinely on a kind of rock and roll science tour, in which Brian has basically gone on with an enormous amount of kind of dry ice and lasers.

And actually going out, they go, Are you ready for Maxwell's equations?

And more often than not, they haven't been.

Well, Carl Sagan, as you know, is one of our science science heroes.

And he once said that in order to make an apple pie from scratch, you must first create the universe.

Now, we all know the universe.

It's a very exact impression, but it turns out it's a very, very niche genre.

Oh, he does all the physicists, Feynman Sagan.

He's not getting much work on the phone.

He's only been dead 30 years, though, so you're pushing your luck, I think.

Well, in this universe, he's been dead 30 years, but in the block universe theory, we still have time.

In fact, no time, it turns out, is actually, you said, a fiction.

Anyway, let's move on.

He does a great Richard Feynman, which sounds like Mr.

Magoo.

I have a friend who's an artist, and he says something I don't agree with too well.

Well, it's my banana.

Anyway, so

now

we all know the ingredients of an apple pie.

Which are apple, pie, and pie, to get the correct curvature of the pastry.

Oh, very subtle.

No, no,

pie is only pie if the surface of the pie is Euclidean.

My pies are always Euclidean.

That's what I have over Mr.

Kipling.

Anyway, the ingredients of an apple pie are up quarks, down quarks, and electrons.

But we don't know the full set of ingredients for a universe by a long way.

The matter out of which the stars, planets, and apple pies are made constitutes only 4.7% of the total energy density of the universe, which means we do not know the nature of over 95% of what's out there.

So, today we'll be investigating what particles remain to be discovered and what is most of reality made of.

To help us decide why matter matters and whether it may indeed be immaterial, whether matter matters, we are joined by a group of people that matter.

And they are.

I'm John Butterworth.

I'm a professor of physics at UCL.

I work on the Large Hadron Collider at CERN.

And my favourite particle is the proton because it's actually the only particle that is both strong and stable.

But But by the time this has gone out, everyone will have forgotten what that meant.

Who knows what happened by the third election of 2017?

I'm Professor Catherine Haymans.

I'm an astrophysicist at the University of Edinburgh.

And my favourite particle is the neutrino.

And that's because

every second, about 70 billion neutrinos fly through the tip of your nose.

And what's cool about them is they were only created in the core of our sun just eight minutes ago.

And And I think that's pretty awesome.

My name's Eric Idle.

I'm a graduate of Trump University.

My favourite particle is the Dawkins particle, the so-called no-God particle.

And this is our panel.

You're a good audience, by the way, for the fact that there were oohs during some of the particle information, and good round of applause as well.

As if we were now let's vote on our favorite particle.

So, John, let's start off with you, which is I suppose one of the questions we get asked most often on this show

is: did Brian really work at CERN, or is that just a media angle?

I'm glad you said did because I can answer affirmatively, yes.

The first paper that I ever wrote on large hydron collider physics was with Brian and his co-author, Jeff Forshaw.

And he did, and he, you were on that FP420 thing, right?

Where we tried to get money to build a bit of detector and they didn't give us the money, so that didn't work out so well.

But

I should have had that paper, which is

still my highest-cited paper, which means it's the most successful.

It's not my highest-cited paper.

No, you've got a bigger one.

His highest-cited is, I think it's called Jimmy the Generator, isn't it?

Yeah, that's true.

Jimmy the Generator.

But that paper, it's got itself, it's WW Scattering at the Large Hadron Collider, and it's about physics at the lhc in the absence of a higgs boson yeah

and still relevant today in in in certain niche ways even though we found the higgs boson yeah is there a small hadron collider

i mean there should be

lots of them there are lots of them yeah can i just ask something though

no because i know most of the audience will know about the fp420 but i'm less aware of it and it was usually it was supposed to detect the protons that missed actually it was a lot like 400 meters away from the main detector, and when protons kind of barely hit each other and carried on, it was supposed to detect them.

It's a process called diffractive scattering.

So the proton can lose a bit of energy but stay intact, and that energy can be converted into other particles, for example, Higgs particle.

So you can have proton-proton collides, and the output of that collision is proton-proton Higgs and nothing else.

And the idea was to detect the protons, they'd lose a bit of energy.

And as you know, as they're passing through a magnetic field, the LXC behaved like a spectrometer, and they would be deviated out of the beams and been collected from the beams in a high dispersion region, 420 meters from the interaction point.

And they didn't leave any money.

Can you believe it?

Anyway, John, this programme's about particles, the fundamental building blocks of everything, as far as we know.

So, quickly, can you list all the fundamental particles that we have discovered so far?

You can actually do it quite quickly because there aren't that many, which is already in itself interesting.

But if you take any bit of material, you'll get to atoms.

An atom is electrons, which is one fundamental particle, the first one to be discovered.

The atomic nucleus has got protons and neutrons in it, which are actually not fundamental, but as you said earlier, made of quarks and gluons.

So we've got six types of quark: there's the up, down, charm, strange, top, and bottom.

We've got the electrons, and they have a neutrino, which is through your nose right now, as we heard,

that goes with it.

And then there are also

that's copied again.

So just like the quarks, there's two light ones and then heavier copies.

The up and down are kind of everyday quarks, and then the other two copies, charm and strange, top and bottom, are heavier.

There's the electron and its neutrino, but then there's another copy of that, the muon and the muon neutrino, and the tau lepton and a tau neutrino.

And everything's made of that, and in fact, pretty much everything's made of the lightest bits of that, so electrons and ups and downs.

And then the way they play together is by exchanging bosons, particles which carry force, and that's the photon, which is what you're seeing me with now, or some of you are seeing with me.

We're on radio, John.

I always forget.

I'm just so used to TV, it's terrible.

They are also the medium by which the sound is being delivered.

Indeed, they are.

That's right, that's right.

Radio waves and light and the lot, photons.

Then there are gluons, which

stick the protons and neutrons and things together, and that's why they're called gluons.

That's the strong force, which is why I said the proton was strong, because it's stuck together by gluons.

And then there's a W and the Z bosons, which carried a weak force, which is the only one the neutrinos neutrinos actually experience.

And it's kind of important in the way the Sun works, but it's the one you always think, How do I describe what the weak force really is there for?

But it's important because the Sun wouldn't work without it, for instance.

So, and that's it, basically.

Except for, of course, the last one to be discovered, which is the Higgs boson, which I always forget.

Inside that, so we've got twelve matter particles,

and twelve matter particles, and then these bosons, there's the W, Z, the photon, and the gluon, which are the three fundamental forces.

And then the Higgs is in kind of in the background.

It is the way all the fundamental particles manage to have mass without making a huge mess in the mathematics and spoiling the whole theory.

Yeah, because that would be wrong.

So a fundamental.

I love the way you say these bosons as well.

It sounds like they really get in the way, these bosons.

But it's,

is a fundamental particle.

So it's basically at that point it will not break down further.

Is that what a fundamental particle means?

That's what it means.

Yeah, we could.

Essentially, as far as we know,

there are two meanings of it, right?

One is that we've not managed to break it yet, which is the experimental meaning.

And that's true.

No matter how hard we smash them together, we can smash protons up, but we can't smash quarks up.

We can't smash electrons up, even though we've known them for over a century.

We've not been able to break an electron.

So that's my definition, if you like.

That's the operational experimental definition.

There is another definition, which is in the theory that we have, in that they all sit, which we call the standard model.

They are actually allowed to be completely fundamental.

They are infinitely small, point-like particles that really do not have any constituents.

And to make that work, you need the Higgs boson, for instance.

And that, but that's just the theory.

Now, they say just the theory because it works incredibly well, so maybe it's right.

But experimentally, it's a kind of always a provisional thing.

If we build an even larger hadron collider, we might actually end up breaking quarks.

Great big mother of a collider.

That's called.

We're actually polling for the name now, but no.

Catherine, we said in introduction that we know, or at least strongly suspect, there are other particles out there.

So, how do we know that?

Okay, so there's lots of different pieces of observational evidence that says that there's something else out there that we can't see and we can't touch, but we know that it's there because of the effect that it has on the things that we can see.

So, I'll start with a piece of evidence that's closest to home, which is our own Milky Way galaxy.

Now, our Milky Way galaxy has got about 200 billion stars in it that are all sort of swirling around, they're moving around.

And what's keeping those stars bound in our own Milky Way galaxy is gravity.

Now, we know roughly how much a star weighs, and we can measure roughly how fast they're moving around.

And there's just not enough gravity from the stuff that we can see in our own galaxy to keep our Milky Way galaxy bound.

So, we postulate that there's a big giant clump of something that we call dark matter

that's surrounding our Milky Way galaxy that's keeping it bound.

And if it wasn't there, then all of the stars in our galaxy would simply fly out into the universe.

They're just spinning around too fast.

So, that's our first key piece of important evidence for there being something else out there.

Is dark matter outside our galaxy?

No, it's it's surrounds us, a giant clump surrounds us all.

In fact,

it's in the room, right?

So, you know, I was talking about

neutrinos flying through you.

There is about between a million and a billion, depends on your model of the dark matter particle.

Between a million and a billion dark matter particles flying through, let's pick your thumbnail this time per second.

But just just like the neutrinos, you don't feel that.

And very, very rarely, maybe once every four hours or so, there'll be a direct collision between one of those dark matter particles and the stuff that's in your body, but you don't feel it.

They're absolutely tiny, tiny particles.

Can you see that?

No, that's just a theory of what we think.

If our numbers are right and what we think the dark matter particle is like, that's

how many would be in this room with us right now.

And how do you calculate something you can't see?

And

you just postulate they bang into each other.

So, there are lots of things that you can say about the properties of this dark matter particle from our observations of the universe.

So, the first and most important thing is it doesn't interact with the stuff that we're made up of.

Because if it did, then we would have detected it already.

You know, these particle physics chaps to my left and right are pretty good at particle physics.

They would have found this particle if it really interacted with the stuff that we're made up of.

It doesn't, so it's weakly interacting.

There are other properties we need, it has to have quite a small cross-section, so that means that it it hardly ever collides with the particles that we're made up of, because otherwise, again, we would have detected it.

And it has to be moving quite slowly, quite a slow particle.

If it was moving too fast, then the galaxy simply wouldn't form in our universe.

But can't we detect it through the l is it so we detect it through light, don't we?

That there's that that it it does interact, right?

Uh it doesn't interact through light.

So I think sometimes when we talk about dark matter, when you think of something dark, you think about sort of blocking out the Sun, don't you?

But that's not true.

Dark matter is actually transparent, light travels straight through it.

The only way that we can detect the existence of dark matter is its gravitational effect that it has on the other things that you see around us.

Although it can bend light, it can bend light, yeah.

So, this is really my research area, gravitational lensing, where we look at how massive clumps of dark matter in our universe curve space-time.

So, when we look at the very distant universe and that light travels towards us from those distant galaxies, that light gets bent and distorted, and that allows us to infer where the dark matter is.

So, actually, I can map out the dark matter for you, and we've done this.

I can tell you where it is, how much of it there is, but I can't tell you what it is.

I understand.

But does it exist only in galaxies, or is it universal throughout the universe?

So, our simulations of what the universe would look like if you could put on some dark matter spectacles and actually see it.

It looks like a giant sort of cosmic web.

And you can imagine it kind of like the scaffolding in our universe because it dictates where and when the galaxies form.

So, the galaxies are kind of like almost like fairy lights that are lighting up this massive cosmic web of dark matter, and they're massive clumps of dark matter, big voids where there's very little, and then filaments that kind of filter all through.

Kind of like roads.

If you looked at a map of our country, you know, you have the big roads that feed the cities, it's kind of the same.

And there's about five times as much of that as there is of the stuff we can see out of which the stars and we are made.

Yeah, so John, in particle physics terms, then, what are the strongest candidates we have for dark matter?

Well, that would have been a really easy question to answer about five years ago because a lot of people thought before the Large Hadron Collider turned on that there was this thing called WIMP, which was this weakly interacting massive particle, which is basically what you just heard described.

If that's true, it interacts with the weak force, and we have a fair chance of creating them at the Large Hadron Collider.

We wouldn't see them, but we would directly, because they don't interact with our detector either.

But we would see that they've been created because they would leave imbalances in the energy of the event, and we can work that out.

And then there are candidates for what might be these WIMPs, and there's theories like a theory called supersymmetry, which you may have heard of, which predicts possible candidates for what a WIMP might be.

There are also other theories that will produce candidates like that.

And there were reasons, kind of some reasons of varying different physicists will put different amounts of credibility on them, but there were certainly indications that maybe these were just about about within reach of the Large Hadron Collider.

That actually, maybe they shouldn't be too much heavier than the Higgs, for instance, that they should be around that energy.

We haven't seen any yet, and we may still, because we've still got a lot of data to look through, but they're certainly not obvious.

We were in the stage of now sifting through the data, whereas I think quite a lot of physicists would have put money on them popping out as soon as we turned it on, more or less.

And

so now there are other candidates, not only WIMPs.

So WIMPS is one of the candidates, so they remain a candidate, but I think they're a less good candidate now because of the data from the Large Hadron Collider than maybe they were five years ago.

Eric, do you find when, because I imagine there's some people in the audience now that you listen to John and Brian and Catherine, and there are little moments where you go, I don't know what's going on now.

This is just, it sounds brilliant, and they definitely, it's real, it must be, because you couldn't look that convincing saying these things.

But there is something about, I mean, because I know you've got really interested in science in the last few, you know, really came back to it.

And this idea for when you're told about matter, for instance, and the human is it, this is matter, it's got to be like this.

And then you're kind of told about the empty spaces, and then they say, Oh, by the way, we don't know what 95% of the universe is actually made of, but don't worry, we are dealing with it, we've got a new whiteboard.

And it's like,

do you sometimes find yourself just going, This is disconcerting, or is it delightful?

Well, it's both, isn't it?

I mean, but the point is, what gets me is that they're talking about massive particles, which are really tiny.

What does the word massive mean?

You know, does it mean it's got mass or it just matters?

That's what it means, yeah.

Well, it's like the weakly interacting force.

When you talk about weakly interacting force, it's stronger than gravity, isn't it?

So

gravity is the weakest force, and that can still really hurt.

And so it's kind of,

yeah, I think it's do you ever think that there is a problem when you're dealing with language, you know, when you come from a background that's not so that it's like with dark matter and dark energy, looking back, probably using dark at the beginning of both of those things has led to a lot of you know confusion for those of us with with more you know humdrum or less scientific rigor.

Do you find it looking at those?

No, I think it's extraordinary, but I find it fascinating because there's this whole field which people are studying and it's all happened really since the early 90s, really.

Just expanded, and it's just a great privilege to be alive long enough to sort of be able vaguely to follow it.

And then it's a field that only actually exists because of various fields as well, including the Higgs field.

So it's a field that without the fields, we have no field.

I would say

it has actually been around longer than the early 90s, even the standard model has.

But what's new, I think, is actually you've got the two astronomers and particle physicists talking to each other in the same language about the same forces and the same particles.

So I think what's really happened is this connection with cosmology has become just much stronger in the last two decades, during our careers, I guess.

So it's interesting that what we've got really are astronomers and cosmologists demanding, or not demanding, but suggesting very strongly there is another particle, which is a subatomic particle the size of an electron.

Or they've got a gravity wrong, you know.

We shouldn't rule that out.

Well, that's an interesting point, actually, isn't it?

Because as you said, the only way we know or we suspect dark matter exists is because of the way that gravity behaves.

So, is it possible that our theory of gravity, which is Einstein's theory of general relativity, is wrong?

So,

when do you stop?

When do you stop looking?

I mean, I guess we were all kind of hoping that you guys would have found this particle by now.

Sorry.

I really feel like you've let us down.

You can't find what's not there.

Tell the wife.

So all all of our observations, and

there are

numerous observations that all support this idea of there being this dark matter particle.

All of those observations are taken in a framework which is based on Einstein's theory of general relativity.

And if we're missing something in that theory,

then maybe we're misinterpreting our data.

And you know, something that would have got me thrown out of the university a decade ago is now really gaining momentum, and people are really seriously questioning our fundamental knowledge of physics.

I mean, when you don't understand something as gigantic as 95% of the universe, that's got to point you towards you missing some key piece of the puzzle.

And it's very sort of widely believed.

And the reason why we're so excited about this is because we believe that that final understanding of these dark components in the universe is probably going to involve some really new breakthrough in physics, some revolution.

You know, just as you know, when Newton was thinking about gravity, he just thought about apple falls on head, ow.

And then Einstein sort of came and said, oh no, it's got nothing to do with sort of stuff attracting stuff.

It's the whole of space-time is curved, and that's how gravity works.

Maybe we need to come up with a different theory.

The key, however, is observational evidence.

So, when you have a big question like this, you know, the theorists have an absolute field date.

There is a zoo of different theories out there, different particles to explain dark matter, different theories to explain dark energy.

There are so many different theories in what we need and what we're going out and getting out from the observational evidence.

That's right.

And the fun thing that maybe you you pick up from that, but people don't necessarily always realize, is that you're not doing this starting from nowhere.

It's like doing a Sudoku or something.

You can't just make up a number and drop it in because you've got all these other constraints from other things you know that your theory does work for.

So you can't just bin the theory and start again, because it's got to be consistent with the data you do have.

And then, you know, so you having a brainstorm and saying

this is the answer, the first thing you have to do is go and check thousands of other things that it has to also get right, not just the new thing that it's got to get right.

There was a there was a time when I started as a particle physicist when we had this conundrum called the solar neutrino problem where the statement boldly put it was either we don't understand how the Sun works or the standard model of particle physics is wrong.

And I think you'll find the astronomers were wrong.

And I was very arrogant.

The astronomers, you call them astronomers, I think it was the nuclear physicists who were right there, which is even worse actually, but never mind.

Yeah, I was thinking, well, obviously the standard model's right, they've got their sums wrong with the sun.

And it turned out, no, the neutrinos had mass and they were doing something funny on on the way to the earth, and it was changed the standard model.

So, this may be that kind of situation.

There's some outlier facts that just mean the data was wrong, and there are some outlier facts that mean actually, no, you've got to tweak the whole theory here.

I should say

the listeners who've been paying attention will notice that we said five percent of the universe roughly is matter, and we said there's five times as much dark matter, which means that's 25 percent.

So, we've got thirty percent of it now.

There is another 70 that we're missing that we haven't discussed yet.

Dark energy.

That's that's this mysterious thing called dark energy.

So it's it's a it's a yeah, it's right.

Dark matter is is strange because we can't see or touch it, but there's so much evidence pointing towards it.

Now, dark energy is different, it's really very mysterious.

What astronomers are seeing is if they look at how fast the universe is expanding, so after the Big Bang, the universe expanded, we always kind of thought that gravity at some point would stop that expansion and pull the universe back in again.

But all of the observations, and there are many different observations, are finding that not only is the universe expanding, but that expansion is getting faster and faster each and every day, which means there's some new form of energy in the universe that's driving that expansion.

And the range of theories to explain that is huge.

But it usually comes down to maybe a new force field or maybe something to do with the vacuum, uh but not necessarily a new particle.

Well the bizarre thing is if you took the Higgs at face value, it would overcorrect for that by a factor of some like ten to the forty-five or something, right, if I remember uh

wrong way.

We should say that's very wrong, isn't it?

Because that's very, very wrong.

That's one with forty-five naughts after it.

Yeah, yeah, I'm not even sure about forty-five, so it might even I think more like a hundred actually

give and take.

But I think we can't do it.

So Higgs is a sort of vacuum energy, right?

But but somehow we just ignored that and say'cause if the Higgs was that kind kind of dark energy, then I think it would, you know, an atom wouldn't hold together for more than the fraction of a second.

Could you just describe briefly, because we mentioned the Higgs a few times, could you describe briefly what that is, what kind of particle that is, what it does?

Yeah, okay.

The Higgs is a unique object.

It's a boson, but it's not a boson like the ones that carry the forces because it has no angular momentum.

They all have angular momentum.

It's sort of a technicality, that bit.

The important thing about the Higgs is that if you take

an absolute vacuum, absolute empty space, and you suck all the energy you can out, if you want to get rid of the Higgs bosons in that empty space, you have to put energy in.

So the lowest energy vacuum

bit of space has Higgs boson, has a Higgs field in it.

Whereas everything, it has no electromagnetic field,

all the other fields have fallen gone.

But if you want to get rid of the Higgs, you have to put more energy back in again.

So

it's got this...

what we call a vacuum expectation value, and it's by that fills the whole of the universe.

And it's by sticking to that field, interacting with that field, that particles acquire mass.

It's the only way we know how to give them a math, give an infinitely small particle a mathematically consistent mass, is by saying there's this field there that's everywhere, and they stick to it.

So, that's the Higgs.

You wrote a brilliant, brilliant song about this.

Sorry, there were two of us suddenly going, Eric, we're now going to give you two questions.

Well, let me say exactly at the same time.

Because Eric has written a superb song about this.

Well, this is what I wondered: are some particles better than others to turn into.

Do you sometimes find yourself going, What a terrible particle.

It doesn't seem to rhyme.

It's rubbish for scanning.

Whereas the Higgs boson, a proper sea shanty.

Yes, well, of course, I misunderstood.

I thought it was a bosun.

You see, I thought it was some kind of nautical term.

And so I wrote a sea shanty, which poor Noel Fielding had to learn and sing.

There's the Higgs boson and the Swastitans and Glue.

What says the Higgs bowsun?

Don't stop there.

No, I can't.

There is.

I didn't have to learn it.

He did.

But you did have one of the finest neutrino rhymes we've ever had.

Neutrino and Brianino in a song is not bad at all.

Yes, the Neutrinos, Positinos, Cappuccinos, I rhyme with it too.

Yes, that was nice.

But there's always something rhymes with something.

There's very few words that don't rhyme.

And it's very nice.

It's kind of interesting.

It's kind of random.

So that's half of what comedy is, isn't it, Robin?

Maybe it's,

but did you find when you see you wrote, I mean, the musical, it has incredible

in terms of some of the scientific ideas, cosmological ideas you do.

And do you find that you sometimes you'll write a song and then you'll mention it to Brian and he'll say, I'm afraid that the current research suggests that that's not accurate.

And you think, but it's a lovely ABAB rhyme scheme.

And he says, We can't have it.

No.

So you, there are moments.

I was very pleased because he once asked me to rewrite the galaxy song about life, and I was very glad to be able to put in deoxyribonucleic acid into a lyric, which is quite nice.

But I'm sure W.

S.

Gilbert would have loved that too, because he was a very, you know, clever man who used, the modern major general.

He's got some wonderful phrases in all about modern Victorian artillery and things like that, which are great.

So it doesn't really matter.

It's like if you can take an idea and turn it into a lyric, there's always something to rhyme.

Have you done anything with eukaryotic?

Because that's a

lot of fun.

Yes, but erotic, of course, is very close to the eukaryotic.

Eukaraoke really is very close to it.

That was weird enough.

We did a gig in Glasgow, and it was the only night of 17 shows where there was a fist fight, and it broke out when he was talking about the eukaryotic cell.

I don't know what he said that was considered so edgy, but genuinely it was that that did happen.

That's what it did.

John, the Higgs part, getting back to the Higgs.

Do I have to do it in rhyme?

So, we

LXC, the particle has been discovered.

So, that theory you described about the empty space not being empty, yeah, I mean, the particle is essentially a little ripple in that field that fills the whole space.

So, yeah, and that proves it's there.

So, that's all developed.

I mean, it's a prediction that goes back to the 1960s, but now we know that's correct.

So, the LXC has discovered that.

So, in terms of the Higgs,

are there things we don't know about that?

What are we doing at the moment at the Large Hadron Collider?

Well, we're in a weird situation because the standard model is now, its last prediction was the Higgs.

The last new particle it predicted was the Higgs.

Without the Higgs, the standard model would definitely have broken down at the Large Hadron Collider.

We would have no theory, or we'd have had a new one by now.

But with the Higgs, the standard model potentially works up to energies much higher than the Large Hadron Collider can reach.

And we're trying to find out: does it really work?

So we're studying physics in this new regime where the Higgs is actually an intimate player on the stage now, whereas it wasn't before.

And we're measuring its mass more precisely, how it's produced, what other particles it's produced with, what it decays to, those kind of things.

It's very odd because the standard model has

kind of complete and consistent now, but it's very clearly not a theory of everything because it doesn't include gravity even, never mind dark matter, dark energy, and doesn't tell us where why there isn't more antimatter around in the universe.

There's all kinds of open questions.

On the other hand, there's kind of no clues to the answers within the standard model.

So we're on a hunt now, seeing whether the predictions, because of the Higgs discovery, we now have real predictions of what physics should look like at the Large Hadron Collider.

And of course, we're testing those, we're making measurements and confronting them with the theory with the data.

But we're also looking for bits where it doesn't agree because they might be the thread that helps us unravel some of these other puzzles.

So, we have a theory.

We should perhaps describe what the standard model is.

So, it's a theory, a mathematical theory.

I thought I'd done that.

It's just those particles that we went through before.

No, but when you talk about a theory, so we have a theory that we can use to predict what happens when we bang protons together at the Large Hadron Collider.

Yeah.

And it's completely consistent with every measurement we've made, high-precision measurements.

However, we're in the position where it doesn't describe everything at all.

So it's kind of like almost segmented off from the problems that we see.

And you kind of focus naturally on the bits where it doesn't work, which are the astrophysical observations, dark matter, for instance, that it doesn't work on.

This is back to what I was saying about the Sudoku, basically, that you've got this whole thing nearly filled in, and you've got one bit that doesn't work, and you're concentrating on that bit, but you've got to keep all the other bits right at the same time.

What about the problem of when you get

the gap between, say, theory versus technology.

So you come up with a theory, and then you go, oh,

the stuff doesn't exist.

The machines that we need,

we can't even as yet imagine how to interrogate that particular part of the universe.

So I'm wondering about from either of you that moment where you go, we just haven't worked out how to investigate this, but we've got it on paper.

Yeah.

Yeah, I want a liquid mirror on the dark side of the moon, please.

See, knowing what you want is

half the value of the market.

It can happen.

And there is technology now which builds mirrors out of liquid mercury.

And

it's okay, dark side of the moon, so don't worry about mercury contamination.

You know, a really, really massive, massive telescope on the dark side of the moon.

Think what you could do with that.

But like it took.

What would you do with it?

I would look really deep back into the early universe.

So, you know, we already have the technology, the instrumentation to be able to take these deep images of the universe, but we just have to stare at one patch of sky for a really, really, really long time.

And that's just because the size of our telescopes, you imagine it imagine it just like a bucket, it's collecting photons as they rain down on Earth.

So if you had a really big telescope on the dark side of the moon that was huge, imagine how many photons you'd collect then.

You'd really rapidly map the first stars, the first galaxies in the universe, and then you'd be able to really confront all these different theories of what these particles are.

So is that that that's going to tell you about how the first stars and galaxies formed and therefore

test the theories of dark matter and how the structures form around that?

Yeah, exactly.

And also, test how the particles that we know about behave in the early universe.

But I mean, I think we should be very flattered as a species because it's only 1926 that we even knew there was a universe.

We thought the Milky Way was the universe.

It's only Hubble, 26, isn't it?

1926.

So, that's not even 100 years, is it?

My math's bad.

It's nearly 100 years, which is extraordinary growth of knowledge.

Now we know

that's reflected through the growth of technology.

So I find you know, major advances in science always come with major advances in technology.

You know, Higgs proposed the Higgs boson, what, 50 years ago?

Yes,

and it took that long to build CERN to go out and find it.

And I think the problem with these dark matter candidates is you don't, you know, with the Higgs theory,

there was only one thing you didn't know about the Higgs boson, and that was its mass.

So,

you could design the Large Hadron Collider to go out and find it.

Now, with these dark matter candidates, there are so many different ones.

We've just talked about WIMPs and SUSE, but there are more out there.

That's right.

It's very hard to get a killer.

You're never going to.

I mean, with the LHC, you knew you would either find the Higgs or the standard model was wrong, and there would be no doubt afterwards.

You know, that was the way it was.

Either you'd find it or it wouldn't be there.

We're not in that situation with dark matter.

We're kind of looking, it's like you know, you've lost your keys in the dark.

You look where you can look, you look under the lamppost, but actually, there's no guarantee they're under the lamppost, it might be somewhere somewhere else.

Whereas the Higgs, we knew the lamppost was big enough.

That is great, that patience, that's what I find fascinating about physics.

That idea that, you know, Peter Higgs comes up with the idea and someone goes, right, this might take a while.

Ring Switzerland and tell them to get the bulldozers out.

You should do some building.

And that is, I think, just a beautiful, you know, we wait, we wait, we build, and then it's actually not quite, it's it's great, I agree, it's great, I'm not going to argue with you, Robin, but it's not quite as monomaniacal as that in the sense that we operate in a sort of heat bath of cutting-edge technologies.

And if you look at the kind of technologies that have been developed by CERN and by Wi-Fi came from astrophysics, and you know,

the

touchscreen controls and stuff were developed at CERN first, and all this kind of stuff.

And it's not just that we're being smart and giving other people technology, we're benefiting from other technologies developed for other reasons as well.

And we're in this kind of virtuous cycle of, and science is one of the reasons we develop technologies, but it's also one of the things we can do with technologies when we have it.

And so it's not like everyone was saying in 1965, right, we're going to work like crazy now till we built the LAC.

There's a lot going on in between.

They would in the movie version where Tom Cruise plays hits.

That'll be.

And yeah, let's not forget, it's not all good.

The internet as well, and thus Trump.

So

the internet is the Pentagon.

It's just the

objective to Tom Cruise, actually, because it's not science, it's Scientology, which is like the internet,

which is one of my favourite sciences, actually.

But

I just find, would you think this would be so?

People now try and think of ways to be able to just find dark matter.

Is that what they're trying to invent an experiment?

Yes, like trying to invent the telescope being Leeuvenhook that made it possible for Galileo, right?

Yeah, it was very, we were always hopeful that these chaps at CERN would create a particle, and they failed so far, so we just wait.

Meanwhile,

meanwhile,

10,000 feet underground in the South Dakota hills, there are massive vats of xenon that are trying to catch one of these dark matter particles.

So they put them deep in these salt mines underground.

It's just literally massive, massive vats.

I kind of think of it like some sort of Dr.

Evil there deep under the ground.

The reason why they're underground is to shield you from all of the other particles that are out there.

And what they're doing is they're waiting for one of these dark matter particles to collide with one of these heavy xenon nuclei.

And then that increases the energy just slightly.

And then they measure that increase in energy.

Now, they've been doing this for quite a while now.

The The technology is amazing, but unfortunately,

they still haven't seen anything.

We're actually purifying stuff for one of the next generation up and up the road at UCL.

In fact, we have a little lab doing it there.

But

I like the idea of Frontiers, right?

So a lot of this now is getting very theory-led, and that's fine, you've got to look for a theory.

But I like the idea that there's

something basic about looking at the universe out there as far deeply as you can.

There's something basic about colliding particles together as hard as you can, actually, because that gives you resolution of a, it's like a big microscope.

You're looking at the structure.

And there's something really basic about the most sensitive detector in the world in a mine somewhere, just watching to see what happens.

I mean, it will is looking for dark matter, but something else might show up as well, because this is the most sensitive bit of the universe we've ever come across.

We've just, you know, we're instrumenting a bunch of really quiet material to seeing what happens in it.

And dark matter is one of the main motivations, the main motivation, but it's just fast.

It's a real frontier, this idea.

Would you expect us to find it within 20, 50, 100, or will it never be?

It depends what it is.

Do you have a wish list, Eric, of thinking that when you're reading about cosmology?

Ah, if only we had the technology or the machine to discover this, is there something you think that's what I want to know?

Well, I mean, I'm just amazed to be alive long enough to have seen this extraordinary expansion.

I think it's one of the best times ever to have been alive.

So,

you know, you can't really hope to be alive forever, apparently.

But I do think it's absolutely extraordinary that, and it also comes out of the war.

I mean, after the war, then science became stop trying to kill each other with newer and better things and start looking at what's up there.

And I think there's still a battle to try and persuade people that's worth doing.

And I personally, that's what I would like to put weight behind.

It is remarkable, actually, when you think that so the neutron, we sort of take for granted now: protons and neutrons make atomic nuclei.

That's That's a 1930s discovery.

And then quarks, 1960s, and the top quark, the 60s,

1995.

Yes, so this is extremely recent.

And actually, the neutrino, the tau neutrino, that's 2000, wasn't it?

Something like that, yeah.

Although we kind of knew that was there anyway.

Yeah, but when we list all these particles,

many of them have been discovered in my lifetime, let alone,

let alone yours, but thank goodness.

Do we save this knowledge?

Because in case we blow each other up, I mean, is there some place that, like, I know, like, say,

Sagan, Carl Sagan put that on to the, was it Voyager one and two has information of what we think we knew then, which was in the 60s or 70s.

I mean, is there anything else?

It's a really interesting,

it's an interesting question.

I read a biography of Dirac, which is really good.

He's a guy.

Dirac is the guy who put together the first

theory of relativity and quantum mechanics, special relativity and quantum mechanics.

He has graves in Westminster Abbey.

Yeah, and he posted, that's right, and it led to the prediction of antimatter, a really big deal.

British physicists work in the mid-20th century.

He was an atheist, he didn't believe in anything, except that he was very distressed by anything beyond the

world.

But he was really distressed by the idea that the wonderful knowledge that he and his colleagues and the human race were discovering would be lost forever.

He didn't really care whether he lived forever, but he wanted his knowledge to live forever,

because he felt it was real and important.

I find that really quite moving.

I think that's true.

And it's kind of what you were asking, and I sort of feel the same way.

I hope that someone

else is.

We all know the universe is going to end in a boring death or something in the end, anyway, right?

Well, that's one of the.

By the way, it was the book you're talking about, The Strangest Man by Graham Farmalow.

Yeah, it's a fantastic book.

The Strangest Man by Graham Farmalow.

What is a strange quark, if I may ask?

It's like a down quark in that it has a charge of

minus a third.

So I start with the down quark.

The down quark is there's ups and downs in the proton and the neutron.

They're just little things with fractional charge that bind together to make protons and neutrons, which make the nucleus.

The strange quark is called strange because it was seen in some strange events, actually.

They were saying, if they're only the two quarks that we know about, they didn't even know about quarks then.

They said these hadrons are behaving strangely, these particles are behaving strangely.

And they called it a quantum number, they called it strangeness.

They said things have a strangeness.

And in the the end, when we worked out what quarks were, they said, oh, that strange behavior was because of this quark.

So we called it the strange quark.

But one of the, you know, I said at the beginning, they're these heavier copies of the fundamental particles.

The strange quarks are the middle heavy copy of the down quark, and then the bottom quark is the even heavier copy.

We should say that there's no known logic to that pattern at the moment, is it?

It's one of the great mysteries.

That's right.

So people are wondering why does the strange quark is.

It's one of the clues we might have.

I mean, the periodic table of elements was a massive clue as to what the internal structure of the atom was.

And this little pattern we have of fundamental particles may be a clue that they're not fundamental at all.

There's some underlying reason behind this because they're built up something else that we don't know yet.

Can I say that?

As you mentioned, the heat death of the universe.

Now, the research always comes up, doesn't it?

Yeah, it always does.

When you say it, at least you say it in a bit of a sad way, whereas he goes, the heat death of the universe.

Oh, jolly.

I should think

our producers sat there going, wind this up, because the heat death of the universe is getting closer and closer.

The terrible.

No, I just jump very quick question because the idea of Higgs

and

I believed that there was a sense that this could question the stability of our universe.

So, how does that change the destiny of our universe in terms of if it's less stable than we imagined?

That's a nice, simple, easy question to end up.

Yeah, and if you could just do that in the equivalent of a tweet

in 140 characters, please.

So, John, is our universe currently stable?

Yes.

great.

That's good news.

It's just a radio formation.

For all practical purposes,

some people get seriously worried about this, that the universe might suddenly vanish in a puff of Higgs.

It's not going to, right?

There is a question about stability or metastability, which means metastability means stable for all practical purposes, i.e., billions and billions of years.

It might not be stable in terms of forever.

And so, in terms of the heat death of the universe, an alternative is it pops out of existence and

goes into a different vacuum state of something or other.

But whichever one it is, it's not on any kind of human time scale.

So, don't worry about it, you people who email me occasionally saying you're worried about this, it's not really worth it.

Which one would you prefer, Eric?

If you could have

a heat death of the universe or a

flash, a reconfiguration of the universe into some other form?

I'm not so worried about the heat death of the universe as the general cooling of my own body.

We asked the audience, obviously because they're the ultimate experts this evening: if you discovered a new particle, what would you call it and why?

So, answers include the coccyle, a particle that sucks the life force out of aging comedians.

That's both of us, Eric.

That's both of us.

Thank you, Eric.

It's very unfair because he's younger than me, you know.

I used to to be, but not anymore.

Is it a klepton?

It steals mass from other particles.

The strong Brexit, because whatever it spin, it collapses.

The crouton.

The cosmic soup must have had croutons.

I wanted a patchoula quark.

So

thank you very much to Catherine, John and Eric.

Next week we're going to be coming from the Starmus Festival in Trondheim in Norway where our panel will consist only of people who have actually journeyed into space including Charlie Duke from the Apollo 16 mission.

And obviously we'll be asking, did you really go to the moon?

We won't be asking that.

When you see our

I've heard in some of the pictures you can see a shadow of Stanley.

Goodbye.

Goodbye.

Goodbye.

I know I've got the podcast, podcast, podcast, podcast version of the podcast, podcast.

Brian doesn't even know that you have actually now listened to the whole of the show.

And this is all he's been doing for the last 47 minutes.

And it's not going to end for a while either.

It's a nested infinity of podcasts.

And you could probably sum it up, I could just.

This is my life.

you just end up with a podcast

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