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1:15

BBC sounds music radio

1:17

podcasts. Hello, I'm

1:19

Brian Cox. I'm Robin Hintz and welcome

1:21

to the infinite monkey cage. And today

1:23

for the final episode of this series,

1:26

we have brought Brian home

1:29

because we are in Geneva at

1:31

CERN. Home of the Atlas experiment,

1:33

the Large Hadron Collider and of

1:36

course also as we know from

1:38

the British tabloid press, the world's

1:40

premier creator of bonsai black holes,

1:43

little mini black holes that will

1:45

undoubtedly ultimately destroy civilisation. So

1:48

how do you make the black holes here, Brian?

1:50

Well, the first thing to say to listeners, this

1:53

is drivel. But you know, you know,

1:55

you want to be remembered for a quote by

1:58

Carl Sagan's Billions and. billions which

2:00

you never said. The cosmos

2:02

is everything there is, everything there was, and

2:04

everything there ever will be. We are all

2:06

made of star stuff. The stuff of us

2:09

is the stuff of the stars. So

2:12

what's your equivalent then? When

2:15

you look up my most

2:17

cited quote in

2:19

all my career, public engagement, public understanding

2:21

of science, it's anyone who says the

2:24

LHC will destroy the world is a

2:26

twat. Yeah. That's it. Anyway.

2:29

Well, also, why we're here, because of

2:31

course you did also pretend to work

2:33

here in the same way you pretend

2:35

to work at Manchester University. And this

2:38

is kind of one of the homes into

2:40

some extent of your most cited paper, isn't

2:43

it? Yeah,

2:45

just before we get going to talk about the Higgs

2:47

particle, then for the listeners at home,

2:50

my most cited paper that

2:52

I've written in physics is

2:55

WW scattering at the LHC

2:57

without a Higgs boson. So

3:01

it was a complete failure in

3:03

that sense. But it's the thing

3:06

that's been my most successful paper. So there

3:08

you go. Failure is

3:10

rewarded in physics. Today,

3:14

we are asking what is the Higgs boson

3:16

and its role in the standard model of

3:18

particle physics? Why was it so important to

3:21

discover the Higgs or to prove its non-existence?

3:23

And now that we've discovered the Higgs boson,

3:25

what next for the Large Hadron Collider? We

3:27

are joined by a particle physicist, a

3:30

particle physicist, someone who

3:32

was nearly a solid state physicist and

3:34

a theology student, because it's the god particle

3:36

after all, and they are. I'm

3:39

Katie Brand. I'd like to

3:41

call myself a theology graduate, if you don't mind,

3:43

because I did leave 20 years ago. But

3:45

always, we are a student of theology, right? So

3:48

I'm Katie Brand. I am

3:50

a writer, sometimes a

3:52

comedian, and an ignorant,

3:54

but willingly enthusiastic sort

3:56

of amateur Physicist. So that's why

3:58

I'm here. And. The

4:01

question were posed tonight was what was

4:03

it? What to do? A Lot. One

4:05

project you'd most like together an international team

4:07

of scientists to so. Yeah, I mean this is

4:09

my dream. It says that. Real pie. In the sky

4:11

stuff right? But I've been thinking about

4:13

it all the way here on I

4:16

think if I to solve anything with

4:18

an international team of scientists it will

4:20

be what since when he smashed particles

4:22

together really fast in a massive underground

4:24

cheese and but I know that's a

4:27

pipe dream I know about. Said

4:29

I'd like them to sell how that is awesome for

4:31

the sleep so easily on the sofa us but when

4:33

I go straight to bed. I'm suddenly wide

4:35

awake. It drives

4:37

me insane. I feel like that's more realistic

4:39

as you guys could help me with that out.

4:42

The Great: forget that she begins to somebody

4:44

about. Worried for me going to take you to

4:46

understand. The but you have the T V P. A

4:49

good visited any might know. I had a

4:51

great time with the tooth. it was great I

4:53

am wrong do I'm a lecturer and thread school

4:55

particle physics and out. The thing that I

4:57

would most like to solve with a team

4:59

of in social sciences is the mystery of why

5:01

is that expose on so lonely. Or

5:09

not, but you won't see any trouble.

5:11

Five for his that that? Oh. I'm

5:14

foreign else I'm a particle physicists lucky

5:16

on the at this experiment with the

5:18

University of Amsterdam and I would like

5:20

an international team of scientists to study

5:22

the mystery of the disappearing cups of

5:25

tea because whenever I make myself a

5:27

cup of tea, I go back

5:29

to coding or watching. Tv and then

5:31

I looked down and it's gone. and

5:33

I hypothesize that there is an alternative

5:35

dimension where it's just made entirely of

5:37

tea and that Fleming's he goes to.

5:39

I'd like to be able to hack

5:41

into that time and since of I

5:43

could have infinite cups of tea. Sets

5:46

my as the if any grandson. Third, listeners.

5:49

Front of us are listening. I'd like to also

5:51

discovered that matter thanks. My

5:54

name is by Miller. I'm an

5:56

actor, the children's author. And

5:59

I actually. The proximate li. Three.

6:02

Quarters of a Phd in

6:04

solid state physics. The puzzle:

6:07

I would like a team

6:09

of scientists to solve His.

6:12

I decided to write up my phd from

6:14

Is. Anna,

6:16

give me a really easy by the

6:19

I mean really really really easy. But

6:21

now I posed the question I would

6:23

like on Sep: A: Particle Physics is

6:25

a mess isn't it? As be honest

6:27

as as get it as just get

6:29

it'll last A the ipad is too

6:31

many particles. The seventy particles you guys

6:33

have just not stops for years and

6:35

the advances want to know. Is this

6:38

enough particles? Now already with the Higgs?

6:40

is this last article or are them

6:42

more. Of. These particles.

6:45

And it's the ah, What? Kind of

6:47

particles are they. Less. Noise

6:49

is so funny for the as my question. And

6:52

this is how. I

7:00

joined up as accent because in the sound

7:03

set you said you'd get between a third

7:05

and a half of the degree nine gone

7:07

up to three precautions against wonder if the

7:09

fractions with a problem when he was acid

7:11

something it's as exotic. The number of times

7:14

I mentioned my phd the closer I get

7:16

when I remember we wait for a joke.

7:18

Once saw a i think is among say

7:20

to his radio show he made and will

7:23

be.your supervisor. Him and we thought

7:25

it was gonna be really lovely and and

7:27

Van has any seats advisor for alongside city

7:29

Was actually quite annoyed. City

7:31

doesn't read over seventy cents and then

7:33

stops at the moment he started writing

7:36

a thesis denise against others he didn't

7:38

quite well as Earth or any fans

7:40

of Cool Blockade. Ah, but yeah, I

7:42

was there right back in. the early

7:45

days are not my name and thus

7:47

month at my soup as might peppers

7:49

at Sea is is actually still absolutely

7:51

furious with me that winter. as

7:54

enforcement this is a very understandably reddit

7:56

see a soldier brine scientists get really

7:58

angry with his says I can't waste their

8:00

time going into showbiz. Anyway, Katie,

8:03

I just wanted to ask you first of all, before

8:06

we get into kind of the full-on science of, today

8:09

was your first day of going down,

8:11

seeing the Atlas experiment, we went, what

8:13

was it, I think 83 meters underground,

8:15

and I think that first experience of,

8:19

what was it for you? Well,

8:21

it is a sort of weird, strangely

8:23

spiritual experience going down there. It's

8:26

like a, you know, the sort of journey to the center

8:28

of the Earth moment, and all the

8:30

stuff leading up to it, it's all quite fun and theatrical.

8:32

I mean, I know obviously there's health and safety things, but

8:35

I just mean me as a sort of someone who comes

8:37

from film and entertainment, I'm just like, you

8:39

have a wire door with no

8:41

unauthorized entry, and Clara had to have her

8:43

iris scanned. This is amazing,

8:46

this is better than my wildest dreams. So the

8:48

whole lead up to it feels to me as

8:50

a layperson, amateur, quite theatrical, and it sort of

8:52

preps you for it. So you feel like you're

8:55

going on a journey to the

8:57

center of the Earth, where something magical is happening,

9:00

where people are trying to solve the universe in

9:02

a giant tube, and then you get

9:04

down there, and you do feel like you're sort

9:06

of, well, I felt anyway, close to the magic.

9:08

And I said to Ben, do you feel like

9:10

you're actually vibrating differently yourself? And

9:13

I just realized it was just, I was just a bit excited

9:15

and slightly hungry. To actually be there

9:17

thinking this is where you do it, this

9:20

is where you smash particles together to find

9:22

out what's really going on in our universe.

9:24

But I was very quiet afterwards. I

9:26

felt quite subdued. It's more in

9:29

your mind what's happening in there. It's not

9:31

the lumps of metal, it's what they're doing.

9:33

I really felt the sort of

9:35

magic of that. Well, that's what we're gonna find

9:37

out today. So we're gonna find out, is it

9:40

magic or is it physics? For

9:42

listeners that don't know so much about CERN and

9:44

Large Hadron Collider and the detectors, could you give

9:46

us a brief summary of what this machine is,

9:49

what it does, and how we detect

9:51

the outcome of the particle collisions? Yeah,

9:54

so we have the Large Hadron Collider, which is a 27

9:57

kilometer long particle accelerator.

10:00

and it's 100 meters underground. And

10:02

we accelerate using radio

10:04

frequency cavities, protons

10:07

and sometimes heavy ions like lead, where

10:09

we strip the electrons away, to

10:11

very close to the speed of light.

10:14

And then we smash them together inside

10:17

essentially giant particle cameras,

10:20

but they're very complicated detectors that

10:22

we have developed over many decades

10:24

in order to study the particles that

10:27

come from the collision. So

10:29

when these collisions happen, we use

10:31

Einstein's equation E equals mc squared,

10:35

where matter and energy are

10:37

equivalent. And we can change

10:39

these particles into different types, or they are

10:41

changed into different types depending on the quantum

10:43

mechanics. And from

10:46

these collisions, they change

10:48

into other types of particles which spread out

10:50

in like a firework shape. And

10:52

then we surround this collision point with

10:55

the detector, which depending on

10:57

where we are in the layers of

10:59

the onion of the detector, have

11:01

a different purpose. So very

11:04

close to the center, we're measuring the tracks

11:06

of charged particles. And then

11:08

we're measuring the energy of the

11:10

particles, and then we're measuring muons. These

11:13

incredibly tiny particles are going at such high

11:15

energies that we need a lot of material

11:17

in order to stop them or to measure

11:19

them. Timon, I wanted to ask

11:21

you about, why was

11:24

it necessary? In the

11:26

1960s, I think, when Peter Higgs and his

11:28

colleagues, kind of, they postulated this idea of

11:30

the Higgs field. What was

11:32

it about the universe? What was it about,

11:35

we understood about the universe, that meant

11:37

that the LHC was required?

11:40

So if we go back to the 1960s, then

11:43

the state of knowledge at the time was that

11:46

everything was made up of matter and

11:48

force particles. So we had the electron,

11:50

we had the atoms that are made

11:52

of nucleons. And there was

11:54

a puzzle of how to give them mass. And

11:57

the theory at the time that described

11:59

things... like the weak force, just

12:02

couldn't account for the fact that the

12:05

particles had mass, and the

12:07

theory itself then also gave you nonsense if

12:09

you tried to calculate what happens when you

12:11

smash things at high energies. So

12:14

the Higgs mechanism and the Higgs

12:17

boson that is a consequence of this

12:19

mechanism was the thing that was necessary

12:21

to make sense of this theory. When

12:24

Clara was talking about that those collisions, new

12:26

particles are made, are they actually made those

12:28

new particles or is it basically like smashing

12:30

a clock and the bits come out, the

12:33

bits that make it, or is

12:35

it at the point of collision that that particle

12:37

comes into existence? So it's

12:39

at the point of collision that the particle

12:41

comes into existence based on the energy that

12:43

was put in. So you don't think of

12:46

the proton as like a bag that contains

12:48

the Higgs boson and all the other particles,

12:51

but in the actual energy when you smash

12:53

them together from E equals mc

12:55

squared, as Clara said, the energy

12:57

is converted into the mass of the

12:59

particles that come out of,

13:01

you could say, a quantum effect

13:03

where you have all these quantum fluctuations from

13:06

the energy and out of this quantum vacuum

13:08

pops out these particles. So

13:10

this is why we need the LHC with a

13:12

high enough energy to then produce

13:14

something like the Higgs boson. It

13:17

might be worth just listing the

13:20

known particles because you mentioned the quarks,

13:22

you mentioned the gluons, you mentioned the

13:24

electron. So could you give us the

13:26

complete zoo, the family as we know

13:28

them today? I think the

13:30

standard model of particle physics is really quite

13:32

simple. There's just, you know, two types of

13:35

particles, matter and force particles. And

13:37

the matter particles are the quarks and

13:39

the electrons, and they

13:41

come in three copies for reasons that no one

13:43

knows. And the force particles are

13:46

the familiar force of electromagnetism, which

13:48

is carried by the photon. You

13:51

have the strong force that holds the

13:53

nucleus together. This is called the gluon

13:55

that carries the strong force. And

13:58

then we know about radioactivity, which is why

14:00

we need the weak force and we call these

14:02

W and Z bosons and Of

14:05

course gravity is the thing that's keeping you all

14:07

in your seats That's you know carried by the

14:09

graviton, but that's basically it. I

14:11

reckon for every Particle you've

14:14

named I can give

14:16

you a role in show business Try

14:20

me with a particle now see if you can tell

14:23

you what role in show business But that's not a

14:25

good one. What's in quark a bottom

14:27

quark? It's quite an easy start

14:29

that one actually for any fans of Shakespeare

14:32

quarks are Fermions

14:34

fermions are a nightmare can't

14:37

share billing Because

14:40

of the power the exclusion principle so

14:43

quarks are Basically

14:45

quark that you weren't right no no

14:47

hang on hang on a

14:50

quark would be a character actor

14:52

quite distinctive Kind of

14:54

not the most important name on the marquee

14:56

try me again a new tree

14:58

no a new tree no is

15:02

a Special guest star

15:05

you don't see them very often, but when they do turn

15:07

up create a big impact Yeah,

15:09

that makes more sense in the quark. Why do

15:11

you think quarks are not important? I'm

15:14

not saying they're not important. It is your actors

15:16

are important. I'm a character I Character

15:20

is important, but you know they're not like

15:22

show offs like electrons You know which basically

15:24

like electron very like a

15:28

lot of lead film actors quite

15:30

small insignificant physically Get

15:32

massive billing everything's about electrons. Oh, we

15:34

have this chemical interaction Oh, I turned

15:36

into an alkali, but yeah, they don't

15:38

really just didn't really justify it You

15:41

know they get all this attention, and

15:43

they're just just but nothing Fermions

15:45

get far too much attention bosons do

15:48

all the work. You've got your

15:50

glue on That would

15:52

basically be a supporting actor They're

15:54

there to really carry the story hold that held everything together

15:56

make sure it all works But they don't really get any

15:58

glory Sivong when you're done You

16:00

mentioned that the Higgs was

16:04

a theoretical idea in the 1960s. And

16:07

you said that that was to build

16:10

a consistent theory. So what do you

16:12

mean by that? So

16:14

when we have a fundamental theory that's

16:17

supposed to describe everything in the universe,

16:20

then we calculate what's supposed to

16:22

happen and it's supposed to give a

16:24

definite answer. And if

16:26

the theory doesn't give a definite answer, then it's

16:28

just a proximate theory, it's a model, it works

16:30

for the things that you're measuring maybe at a

16:33

certain energy scale that you could only access in

16:35

the 1960s. But

16:37

you know that nature does something when

16:39

you collide particles at higher energies. So

16:42

the Higgs mechanism is the

16:45

thing that Peter Higgs, as

16:47

well as lots of people came up with,

16:49

in the 1960s came up with this mechanism,

16:52

was essentially solving this very mathematical problem.

16:54

And you couldn't just write down in

16:56

your equations a mass term. The

16:59

other way to understand why the Higgs

17:01

boson is necessary is to

17:04

simply take the WW scattering

17:07

and take the kind of paper

17:09

that you bought where you didn't have a

17:11

Higgs boson in there and then

17:13

simply try to make it work by adding things to

17:15

it. Could I just ask you

17:17

a quick question? So the scattering is

17:19

just part of the experiment and that's what

17:21

happens, no? Yeah, you just take two

17:24

W-bosons and smash them together. And

17:27

as they scatter, that's what you're measuring. So

17:29

that's what you call the WW scattering. And

17:31

after that you find the Higgs boson that

17:33

creates this drag. That's

17:35

one way in which you could discover the

17:37

Higgs, yes, by smashing together two W-bosons. And

17:40

then the Higgs comes out and then it decays

17:42

into some other particles and you

17:44

look for those other particles and

17:47

if you see enough of them and they reconstruct

17:49

the energy of the Higgs, then you've discovered

17:51

the Higgs boson. Cleric, Tevong's a

17:53

theorist and made that sound really simple.

17:56

Yeah, I was thinking the same thing. You smash a few

17:58

particles together, make a Higgs and then... It

18:00

Could you elaborate? It's not easy. I

18:02

mean we had Subway and so we

18:04

have the energy of the Lhc to

18:06

be a will say even create the

18:08

Higgs Boson Abbott. And the other big

18:10

challenge is designing and building these detectors

18:13

that can measure all of the particles

18:15

that come from the collisions really are

18:17

also have to decide which particles to

18:20

select. We have the understand our the

18:22

tracks or an incredible detail because the

18:24

way that each Pasco interact with each

18:27

section of the detector isn't so simple.

18:29

it's. Not. Like we always know

18:31

the correct answers. And and

18:33

then also their six bytes on patrol.

18:35

It changes into my says the bottom

18:37

plot but because clocks don't like to

18:39

be by themselves the very sociable they

18:41

are hadron I said they form has

18:43

and then they freeze. Jets and are

18:46

detector which to spray the particles

18:48

and. We have a lot subjects and other types of

18:50

because of all those. Clots and gluons also

18:52

in the in the proton and

18:54

so being able to distinguish these

18:56

big blocks from other. Debts is

18:58

very difficult say the actual discovery

19:01

of the higgs by song was

19:03

with events it was less likely

19:05

to change and see, but. That

19:08

were much cleaner signal in our detector

19:10

threat to collect enough data of this

19:12

very rough process to be able to

19:14

see that there was a new Pottsville.

19:17

Remarkable thing. Think president, you have seven

19:19

thousand tons of the sensors. You describe

19:21

the this on the I'm tremendously complex

19:23

machine and you're looking for two. Photons,

19:27

To particles of like. Us

19:30

all. Remarkable. Hey,

19:35

I'm Ryan Reynolds. At Mint Mobile, we like

19:37

to do the opposite of what Big Wireless

19:39

does. They charge you a lot, we charge

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you a little. So naturally, when they announced

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limited time. Unlimited more than 40GB per month. Full

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terms at mintmobile.com. Just

20:09

to reverse a bit. So there'll be people

20:11

at home in the audience. There

20:13

may be people asking why. Well,

20:17

Katie. Well, no, I'm not going to attempt

20:19

to answer that. As a layperson

20:21

trying to get to grips with this physics, that's

20:23

exactly what I was thinking, Brian, as well, is

20:25

that you always want to have this feeling of,

20:27

yeah, this is really, really interesting, and it gets

20:29

more and smaller and smaller, and it gets more

20:32

and more complex. But

20:34

what's the real world application? What's

20:37

the impact on a person like me?

20:39

My motivation to do this research,

20:41

my first motivation is to understand

20:43

the universe better. And it might

20:45

not have any direct impact

20:48

on the day-to-day life right now. So

20:50

discovering the Higgs boson was a huge

20:52

achievement. It's one of the greatest scientific

20:54

achievements of the last 15 years.

20:58

But right now, it has no impact

21:00

on anybody's day-to-day life. But

21:02

for me, it's what makes us

21:04

human, the same reason that we

21:06

make art and that we listen to music

21:09

and that we love to dance. We want to

21:11

know how our universe works.

21:14

And for me, that's a good enough reason in and

21:16

of itself. But the technology

21:18

that we need to answer those questions

21:21

is technology that doesn't exist yet. And

21:24

so the challenges of having to

21:26

build a large Hadron collider to

21:29

build these detectors to measure these

21:31

highly energetic but tiny particles has

21:34

to be invented. And through doing this

21:36

process and also because of the

21:38

ethos of CERN and the whole reason it was set

21:40

up, we just released all

21:43

of our results and all of our

21:45

technology to everybody. And from that, there's

21:47

medical technology that's come from the research

21:49

we do, so PET scanners. I mean,

21:51

now we have anti-matter machines that could

21:54

look inside the human body and are

21:56

able to see what's going on inside of

21:58

there. And that's come from particle physics. physics and

22:01

physics research. And there's also

22:03

hadron therapy, which is

22:05

a new and better way to do

22:08

cancer therapy. So the medical

22:10

technology that comes from this research is

22:13

really important. There's also some really cool stuff

22:15

too, like being able to look behind paintings

22:17

without damaging them. And that's not

22:19

something we're specifically setting out to do

22:21

at CERN when we do this research, but

22:23

the technology that comes from it does impact

22:26

a lot of everyday lives. I mean, televisions

22:28

used to be particle accelerators before they got

22:30

flat. And Ben, you write very widely about

22:32

science. You write children's books about science. So

22:35

how would you answer that question if someone was to say

22:37

to you, well, why, what is the use of this? Just

22:39

acquiring knowledge? What is the point? Well,

22:42

it's about exploration, isn't it? We're

22:44

an explorative species. We

22:46

want to know what's at the boundary and beyond

22:48

the boundary. We also have

22:51

a spiritual dimension. We have

22:53

a desire to know whether there's design in

22:55

the universe. We have a desire to know

22:58

what came before the universe. We

23:01

so enjoy asking questions that

23:03

we are prepared to pursue

23:05

them to any length. I

23:07

think that's one of the reasons we've

23:10

been so successful as a species. I

23:12

find it strange the other way around. You

23:15

know, there's an announcement. We've discovered that the

23:17

Higgs boson is it. Guess what? Particles

23:19

haven't got mass. They get the mass from this

23:21

incredible field. The field is communicated

23:23

by a particle called the Higgs boson.

23:25

And they go, yeah, not really turning

23:27

me on. You think, what is the

23:30

mass with you? These are

23:32

the fundamental questions that underpin it all. You

23:34

know. But that seems to me one

23:36

of the great things that came out

23:38

of CERN and the LHC. It was

23:41

on mainstream television, on prime time news

23:43

shows, there were people explaining the Higgs

23:45

field, explaining the Higgs boson. This

23:47

should be the Trojan horse to get people

23:50

more excited to know what they're made of

23:52

and what everything they see around them is

23:54

made of. I think the

23:56

fact that the Higgs boson has become a household

23:58

name, I think really speaks. volumes

24:01

about the fact that the public is

24:03

interested in these big fundamental questions. And

24:06

there's sometimes a sense where it is a bit

24:08

esoteric, that we're just discovering particles left and right,

24:10

and that, oh, look, the W mass is a

24:13

bit different than what we thought it was. And

24:16

I think this is

24:18

not really capturing what we're doing it for.

24:20

It's not like we're playing Pokemon and we've

24:22

got to catch them all, you know. It's

24:24

not because they... That

24:26

will be really fun. It's also a part of the fun.

24:29

But the Higgs boson, you know, wasn't just the last

24:31

missing piece that we had to find, because we wanted

24:33

to collect them all, but because it

24:36

is fundamentally different to anything we've ever

24:38

seen before. And it's

24:41

something that is at the heart of many

24:43

mysteries of things we still don't understand about

24:45

the universe. So getting to higher

24:48

entries, getting to measure things more precisely,

24:50

looking not just at particles, but at

24:52

the cosmos and what's out there, is

24:55

a way of getting closer

24:57

to nature's fundamental truth. What

24:59

is the underlying elementary particles

25:01

and the basic fundamental forces that

25:04

governs everything. You said something powerfully

25:06

true there with the Higgs boson

25:08

is like nothing we've ever seen

25:10

before. Could you dig a little bit

25:12

more deeply into what

25:14

the Higgs mechanism is and how

25:18

the Higgs mechanism entered the

25:20

universe as far as we know? We've

25:23

basically seen all the different types of

25:25

things that nature can do. And

25:28

we've seen the matter particles, the force particles that

25:30

are allowed. And the last thing

25:32

in a sense that could also be

25:34

allowed is the Higgs boson. And

25:37

this was what was needed to give masses to all

25:39

the other particles. So the

25:41

way in which the Higgs does this is

25:44

to break what's called

25:46

electroweak symmetry. So this

25:48

is a symmetry between the weak force

25:51

and electromagnetism. To explain

25:53

what a symmetry is I would give the

25:55

analogy of if you have two twins that

25:57

are naked, you can't tell them But

26:01

if you put clothes on them, then now you

26:03

can tell one of the twins from the other. So

26:05

the weak force particles are like

26:08

these twins, but there are three of them, so they're actually

26:10

triplets. And these triplets, you

26:12

can interchange them in your theory, and the

26:14

theory stays the same. You can't tell the

26:16

difference. So the Higgs boson is

26:18

the thing that dresses one of these and

26:21

distinguishes them from the other two twins. And

26:24

this other particle is dressed

26:27

up and looks kind of

26:29

fancy, so it goes off and marries

26:31

another particle. What sort of things do

26:33

they wear? Retro punk, or what's the ideal

26:35

kind of outfit for each one? So this

26:37

Higgs boson dresses up one

26:40

of the triplets and dresses that in

26:42

a nice suit. This particle

26:45

goes off and marries another force particle. Let's

26:47

say you're wearing a nice Vivian Westwood outfit.

26:49

Exactly. It's kind of quite attractive, a bit

26:51

sexy. And we give them a name. We

26:53

call them the photon and the Z boson.

26:56

They pair up, and that's what we call the electromagnetic

26:58

force and the weak force, the

27:01

Ws and the Zs. Ben

27:03

mentioned the cosmology.

27:05

So what do we know

27:07

about the way the Higgs began to

27:09

play that role as the

27:12

universe unfolds from the Big Bang onwards? Everywhere

27:14

around us is the Higgs boson with

27:17

an energy configuration that enables it to

27:19

do its job to give masses to

27:21

the other particles. But as

27:23

you go back to the Big Bang and

27:25

as you go back to the early universe

27:27

when the temperature was higher, then the energy

27:29

configuration of the Higgs boson was different. So

27:32

you think of this energy

27:35

configuration as being above the

27:39

kind of energy configuration that it is in

27:41

now. And we visualized

27:43

this by, say, a Mexican hat, where right

27:46

now it's sitting at the bottom of the

27:48

Mexican hat. And in the early

27:50

universe, it had more energy, and it was

27:52

sitting somewhere at the center of the

27:54

Mexican hat, at the top of the hat. So

27:57

when it's sitting at the center, then

27:59

it's switched off. It's not giving

28:01

mass to any of the other particles

28:03

and as the temperature of the universe

28:05

drops since the Big Bang Then

28:08

at some point the energy configuration allows it to

28:10

go to this value that it

28:12

has nowadays and do its job but

28:15

we still don't know how that transition happened

28:17

and This is

28:19

one of the reasons why we want to understand

28:21

the Higgs better. So we understand this cosmology clear

28:24

I just wanted to because that's very there

28:26

was a point there about five minutes ago

28:28

where we had possibly the first time where

28:30

a subatomic particles were beginning to enter RuPaul's

28:33

drag race and I'm

28:35

kind of intrigued because also talking about

28:37

when you mentioned for instance, you know,

28:39

the Mexican hat the Physics

28:41

it seems to me especially particle

28:44

physics. It's always looking for good

28:46

metaphors and for good similes So

28:48

how difficult is it to find

28:50

the the best translation the best

28:52

visual Translation for

28:54

something which is very hard to

28:56

picture in itself. Did you

28:59

have a favorite one? Yeah, my favorite one is

29:01

a snowfield so the the

29:03

Higgs field is the field of

29:05

snow throughout the whole universe and Then

29:07

the particles get their mass depending on

29:09

how much they interact with that

29:12

field And so if for

29:14

example you imagine a skier who's got some very

29:16

nice skis going across the top of the snowfield

29:19

This is like a photon. It's just

29:21

essentially not it Well a photon I would

29:23

imagine was on a paraglide not even interacting

29:25

with the field at all and then Somebody

29:28

on skis is like an electron. It's kind

29:30

of touching it a little bit but not

29:32

interacting too much And

29:34

then my favorite particle is the top quark So

29:36

a top quark is like in in snow boots

29:38

So they've taken the skis off and they're

29:41

just trudging through the snow And and

29:43

then the Higgs boson itself is

29:45

an excitation of the Higgs field

29:48

So the Higgs boson is a snowball and

29:50

so once you've discovered the snowball You know

29:52

that there must be this field of snow

29:54

somewhere that the snowball came from If

29:57

there is a department here at CERN that comes up with the

29:59

message Is there the metaphor department? Because

30:03

Ben and I could maybe, sort of with a

30:05

bit of practice, just man that for you. Like

30:07

you could come and explain it to us and

30:09

we'll sort of mostly understand it and then we'll

30:11

come up with just a list of metaphors that

30:13

you can use. We can have a little booth somewhere

30:15

near reception. You've got that

30:18

little kiosk as you go in that sells

30:20

the hats, which I think is a bit

30:22

mercantile, frankly. Yeah. It sells the

30:24

hard hats with CERN written on. I

30:26

did get CERN. Have a care people. Yeah. We

30:28

can have a little booth there and you

30:31

basically, you know, you can just sketch an outfit

30:33

and I'll tell you which type of actor that

30:35

particle is. I

30:37

think we'll get there very quickly.

30:40

I do want to ask though, in

30:42

all seriousness, you know, my question

30:44

at the beginning, you know, about other particles and you

30:46

know, we've talked about where we've got to so far

30:48

and we found the Higgs and we know what its

30:50

mass is. But

30:53

you know, what other things might

30:55

there be out there? What other

30:57

particles might there be to discover?

30:59

Presumably they'd be heavier than

31:01

the Higgs. Is that right? They'd be

31:03

either heavier or too weakly coupled for us to

31:05

have detected so far. So they could just be

31:07

very, very shiny. But they

31:10

could also be much heavier than what we

31:12

expected. You know, the reason why

31:14

I said that the Higgs boson is lonely

31:16

is because we expected it to have friends,

31:18

you know, in many of the theories that

31:21

we thought would have

31:23

solved the mysteries associated with the Higgs

31:25

and other aspects of the standard model.

31:29

All of these theories predicted that we'd discover

31:31

not just the Higgs boson, but you know,

31:33

maybe a second Higgs boson. Maybe

31:35

we'd discover other matter particles. Maybe other forces

31:37

would have shown up. So there

31:39

was a lot of excitement when we found the Higgs as

31:41

expected, followed by a lot of disappointment

31:44

and puzzling and you know, self-doubt

31:46

and questioning whether or not we even

31:48

had the right principles and the

31:51

right theories to begin with. So

31:53

we still haven't seen these particles. And

31:56

this is making the situation actually

31:59

very interesting. and in some ways

32:01

more exciting, because it means

32:03

that we may be missing theoretically

32:05

some new idea, something radically different

32:07

to what we expected or anticipated.

32:10

I was wondering, is there anything you're

32:12

sort of scared to discover that would

32:14

make you nervous or do you think, oh, I

32:16

think that might exist mathematically? One of the biggest

32:18

mysteries in the universe is what is dark

32:20

matter? This has been measured and

32:23

observed cosmologically, but we don't know. But

32:25

what do you think, by the way?

32:27

Dark matter, it's been observed by galaxies

32:29

rotating too fast. So through

32:31

many different observations, we've seen that there's

32:33

something very massive in our

32:35

universe. Everything that we understand, the standard model that

32:37

we've been talking about, it only makes up 5%

32:39

of our universe. And

32:42

so we don't know what dark matter is. The

32:45

only thing that we know it has is gravitational

32:48

effect. But

32:50

we're also, and it's one of the reasons

32:52

that sometimes people say, you've discovered the Higgs,

32:55

what rate are you done now? Is it time

32:57

to turn the LHC off? And it's not because,

32:59

first of all, we want to understand as much

33:01

about the Higgs as possible. But

33:03

also because we know that dark matter

33:05

has a gravitational effect, it

33:08

could be that it gets its mass if it's

33:10

a particle, and it might not be, that

33:13

it might get its mass from the Higgs mechanism

33:15

the same way that other particles do. And

33:18

in that case, by studying the Higgs boson

33:21

as precisely as possible, we're looking

33:23

for differences between the standard model

33:25

predictions and what we actually measure

33:27

in our experiments. And

33:29

then that could show that something else

33:31

was happening with the Higgs field

33:34

that can't be accounted for with the quarks and

33:37

the other particles that we've measured. So

33:39

it's a really great way that we can use

33:42

it as a link between the Higgs boson and

33:44

potentially being able to understand dark matter. Oh,

33:47

I just wanted to say that we also see

33:49

dark matter in the early universe. So it can't

33:51

be planets because we see the effects of dark

33:53

matter in the light from the Big Bang, the

33:56

cosmic microwave background. So

33:58

we know already from that that there was a with

34:00

some kind of dark matter particle. And

34:02

it's not as exotic as it sounds. We already

34:04

know of a particle that doesn't interact with the

34:06

light that exists everywhere in the universe. Even

34:09

here and right now? Even right now, going through

34:11

it. So the Large Hadron Collider is full of

34:13

it. Everywhere. You're full of it.

34:15

I'm full of it. Exactly. That's

34:17

a fact of the talk, right? So

34:20

there's a billion of these particles going

34:23

through your eyeball every second,

34:25

right? I just want to clarify, because

34:27

we're coming towards the end, Tivong is

34:29

talking about neutrinos, which

34:31

are particles that interact only via

34:34

the weak force. And I thought,

34:36

he said this remarkable thing, that

34:39

billions of them are passing through

34:41

your head now. But only

34:43

you. That way I'm here.

34:47

So one of the ideas, to bring it back to dark matter,

34:49

one of the ideas is that perhaps

34:51

dark matter is a particle that

34:54

interacts by the weak force. But

34:56

then you need an awful lot of them passing through

34:58

your detectors to have a very slim chance of seeing

35:00

them. And we have

35:02

experiments that try to do that. Or it would

35:05

be very unlikely we would make a dark matter

35:07

particle in a collision at the Large Hadron Collider.

35:10

But we might. Yeah, so we're

35:12

often looking for things that are missing in

35:14

our measurements. So we don't just measure the

35:16

particles that come out and

35:19

only measure those.

35:21

We also look, for example, missing

35:23

momentum. So we have conservation

35:25

of momentum in our detector. And

35:27

so we can tell when stuff

35:29

is missing. And neutrinos are

35:32

very, very light. So if we got stuff

35:34

missing that was very heavy, then

35:36

that would be an indication, for example, that there

35:38

could be dark matter in the measurements.

35:40

And we're also doing some new techniques. Because

35:42

we've always assumed that the collisions happen

35:44

and these particles are so short-lived that

35:47

whatever they change into happens right at

35:49

the heart of the detector. And so we've trained

35:51

all of our algorithms to select for the data,

35:53

to look for stuff happening in the center. But

35:55

it could be that dark matter or some other

35:57

new physics travels a bit of a

35:59

distance. distance through the detector before it

36:02

then changes into something we could measure.

36:04

And we call these long-lived particles. And

36:06

so it could be that they're interacting

36:08

at the edge, and so we

36:10

have to redesign all of our algorithms to look

36:13

for things that are happening there. Yeah,

36:15

it's great, isn't it? So they could be there in the

36:17

data. Yeah, they could already be there, and we've just not

36:19

been looking for them in that

36:21

sense. So that's one of the other ways that

36:23

we're trying to innovate and think, well, how else

36:26

could it show up in our detector? This

36:28

idea of the universe having mass, it was the

36:30

first time that I'd ever thought of when I

36:32

started reading about the research that

36:34

was going on. So could you have a universe

36:37

without mass? You

36:39

could have all kinds of universes. It just wouldn't

36:41

be one in which we could survive or live.

36:44

Right. So if the Higgs,

36:46

in fact, its energy configuration right now in

36:48

our universe, in the standard

36:50

model of particle physics, as best as

36:52

we've measured the parameters of this theory,

36:54

is telling us that the

36:56

energy configuration is not stable. So

37:00

it could change to another energy

37:02

configuration and induce

37:04

a catastrophic vacuum

37:06

decay death of the universe that would just

37:08

wipe out the entire universe. I would

37:10

like to clearly state here that

37:13

the Large Hadron Collider would have nothing

37:15

to do with it. No,

37:17

we will be cutting out your bit

37:19

at the end. We keep it. If

37:21

I was Dan Brown, I'd keep that

37:23

answer there. Wait a minute.

37:26

You're saying that we've

37:28

built this collider to find

37:30

the Higgs, which holds

37:32

everything in the universe together, and

37:35

you've discovered it's unstable. That's

37:38

what you're talking about. Within

37:41

the standard model of particle physics, yes, which

37:43

is why we really hope that there's something

37:45

beyond it. Although it's actually

37:47

very slightly unstable. He needs

37:49

to get built in the next one now. He needs

37:52

to get in the next one. What are you doing?

37:54

We're calling a cliffhanger. That's just one word. Why are you

37:57

sitting here doing a radio show? You have it going off.

38:00

toolbox out, start making the name as

38:02

well. Just to reassure you, if it

38:05

is indeed unstable, it was unstable whether

38:07

we detected it or not, that it's

38:09

got nothing to do with us. It's

38:11

got nothing to do with us. I didn't

38:14

know then, nothing told me, it's got to,

38:16

that's just really inconsiderate. Yeah,

38:19

advocating for ostrich-like behaviour, why does it matter?

38:21

Are you saying that if you don't know?

38:23

We enjoy these last few minutes, we've all

38:26

got together and see what we ask the

38:28

audience. It's an old experiment then,

38:30

after the audition, where you still don't know if you've

38:32

got the part or not, and for a while you'd

38:34

rather not know, it's like that, isn't it? How

38:37

are you so calm about all of this? How are you

38:39

just sort of, yeah, well if we knew the universe was

38:41

unstable then it would have all gone to pieces by now.

38:44

How are you so relaxed about

38:46

this situation? It's not everyone else

38:49

really stressed by this. But

38:51

he finished his degree and he's worked out, get

38:53

out, you all. Just

38:59

to finish, just to point into the future, it's

39:02

a signal that there's something

39:04

deep that we don't understand. Right,

39:06

so some theorists, like myself

39:08

and many of my colleagues, do try

39:11

to explain this by saying

39:13

it wasn't an accident. Maybe some

39:15

dynamics in the early universe actually balanced

39:18

the Higgs boson right at the edge

39:20

of this precipice, and this

39:22

is something that we're actively trying to look for

39:24

other signals for. Is this supposed to be reassuring?

39:26

We're on a precipice, at least we're still on

39:28

the precipice. Yes, look at the bright side. Anyway,

39:31

we've run out of time so we're going to

39:33

just, we ask our audience a question as well,

39:36

as we always do, and we wanted to know

39:38

what is the secret of the universe you would

39:40

most like to uncover and why. Brian, what have

39:42

you got? You know, we asked you before

39:44

how many of you are physicists, and

39:47

you said about most of you are physicists,

39:49

right? Usually when we ask this question, the

39:51

aim is to generate humorous

39:54

answers. Yes. In this case, they're

39:56

all very specific and precise. Yes.

39:59

There actually are. answers to the

40:01

question as posed. So for

40:04

example where does it

40:06

stop? So the joke

40:09

is what is the secret of the universe most you

40:11

most like Sun, Cobra and why? Where

40:13

does it end? Do jazz hands.

40:15

I'll do jazz hands for my one,

40:17

dark matter. So there we go

40:20

yeah that didn't still didn't quite get it working did

40:22

it? Is space-time just

40:24

a side effect of all a selection

40:27

of quantum fields trying to achieve

40:30

their respective lowest possible energy states?

40:42

This one right now I'm gonna do it

40:44

right okay so all right now Gemma. Oh

40:46

no Gemma. Now what is the secret of

40:48

the universe you'd most like to uncover and

40:50

why? I'll tell you my one. My one

40:52

is what's the rest difference between rest and

40:55

virtual particles? I gave

40:57

it everything mate I gave it absolutely everything there.

40:59

This is from one of the few non-physicists here

41:01

where do all the socks end up? Yeah

41:05

the one that I particularly like here is why

41:07

in the UK are bathroom hot

41:09

and cold taps separate? If

41:18

that was the biggest issue the UK were dealing with

41:21

now why would that be? And

41:24

then finally of course how come and this is a

41:26

science course how come Brian Cox doesn't age? Because

41:30

I do all his ages for him right? I'm

41:32

one year younger than him when we started working

41:34

to go. In fact if you might have seen

41:36

there was a visual beforehand where I had lovely

41:38

dark hair and it was all over my head.

41:40

Not since I've worked with him. No no. I

41:42

was gonna say I do age at the normal

41:45

rate it's just the contrast. Yeah. Right.

41:48

One of you just moved much faster

41:50

through space-time than the other. Well

41:53

that's all we've got time for. Thank you to

41:55

our panel. Dr Clare Nellis, Dr Tevong Yu. Not

41:58

doctor or professor but he should have been. It

42:01

was completed his PhD, Ben Miller

42:04

and not Archbishop or Dean but she's

42:06

glad that I believe she's not an

42:08

archbishop or a deity brand. That's

42:15

a fitting end to our series. We've learned

42:17

that we are on a precipice. We

42:20

began with Egyptian mummification and we've ended

42:22

up with elementary particles. Now of course

42:24

what Brian didn't actually know about today's

42:26

episode is that this was actually a

42:28

honey trap to get him back to

42:31

Geneva under the instructions of

42:33

CERN's governing board because apparently 12

42:36

years ago he was in the middle of the

42:38

meeting and just suddenly went hang on a minute

42:40

I've just got to pop out I've just got

42:43

to get into a helicopter for a while and

42:45

talk about super luminous super nova for the BBC

42:47

but I'll be back in a minute and he

42:49

never returned thus breaking his

42:51

contract. So now he is here

42:53

he's not allowed to leave CERN

42:55

for two and a half years until

42:57

his contractual obligation is met. So

43:00

I'm going off on holiday for a few

43:02

weeks you have work to do to make

43:04

sure we don't fall down that precipice. Bye

43:07

bye. Thanks

43:28

again. So

43:59

if that sounds like fun. you can check out our

44:01

back catalogue and our new series on BBC

44:03

Sounds. Just type in your dead to me

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and hit subscribe. Thank you, bye!