Horizon (1964–…): Season 47, Episode 8 - What Is One Degree? - full transcript
'I'm Ben Miller.
'I'm a comedian, but for six years
I was a physicist.'
Wow!
'Something really embarrassing
happened to me recently.
'Someone asked me what seemed like
a basic scientific question,
'something that should have been
second nature
'to someone with my background.
'They wanted to know about
temperature.'
Glorious.
That's 19 degrees.
'And try as I might,
I couldn't answer them,
'so I've decided to go on
a physics refresher course...'
Wow!
'..to investigate
the secrets of temperature.'
Oh, you beauty. Look at that.
My life has purpose again!
BEN LAUGHS
I feel like, er...
I feel like I'm actually
doing something useful.
'One degree might seem like the most
basic of concepts, but actually,
'the more you delve into it,
the deeper...'
That is mind-blowing! Look!
It's also very cold.
I've gone through the rabbit hole
and I've ended up
somewhere I just never
expected to be and it's disturbing.
'..the stranger...'
So heat is a form of energy.
Well, this is the profound thing.
Actually, there's no such thing
as heat. What?!
'..and the more surprising
temperature becomes.'
So going to show me your weather
station then? Oh, yes. Of course.
'So I need an answer.
'What is one degree?'
Er, how's it going?
Portion of chips, please.
'Most of us don't give much thought
to the question of temperature,
'to the difference between
'say an ice cream
at minus 16 degrees Celsius...
'..and a cup of tea at 82.
'But for me, behind these
apparently simple questions
'lurk some of the deepest, most
fundamental scientific mysteries
'in all of nature.'
You know, recently I've been
thinking a lot about temperature.
I was at this dinner party
and I was sitting opposite a woman
and we started
talking about climate change
and I was saying to her how
the planet's temperature's increased
and she was disagreeing with me,
saying, "No, it hasn't.
"They don't know that for sure."
And the more I tried to explain
about temperature and what it was
and how we could definitely measure
it, the more I started struggling.
And then I started thinking,
"Hang on, I used to be a physicist.
"If I can't explain this stuff,
who can?"
'There's no getting away from it.
I couldn't answer her
'and that's why I've decided to
return to my roots as a physicist
'to find out what one degree
really is.'
I've been thinking
about one degree...
and I'm beginning to get
a familiar feeling
that I used to have,
studying physics,
which is you kind of...
You start out with something
that seems very simple,
that you just want to define
in a straightforward way -
something like temperature -
and the more you think about it...
..the deeper the layers get and the
less you feel you really understand.
You know, this really
isn't going to be easy for me
because I can't remember, really,
in detail, anything that I studied.
"Novel quantum effects
in low temperature, mesoscopic,
"quasi-zero-dimensional
electron systems."
Yep, that was the title of the PhD
I embarked on here in Cambridge
after completing my physics degree.
You know, this is a really fitting
place to be starting this journey
because this is where...
I mean, this is where modern
physics started really.
This is the spiritual home of
physics - the Cavendish Laboratory.
This is where everything happened -
Ernest Rutherford split the atom,
JJ Thomson discovered the electron,
GI Taylor discovered
the quantum nature of light.
It all happened here.
It's where Ben Miller
studied for his PhD.
Aaargh!
'After 20 away from the lab,
I knew I'd need help.
'I decided to look up
my old supervisor...'
The prodigal returns!
'..the leading
semiconductor physicist
Professor Sir Mike Pepper.
'Mike was always the guy you went
to to put you on the right track.
'Mike has a brilliant way of
being able to
'explain complex ideas
really, really clearly,
'and just with a few words,
'he would just kind of
put you back on the beaten track.'
A couple of photographs here
with you on them. Right, yes.
The lab photos, the hall of fame.
There I am.
That's it. With bleached-blond hair.
Yeah, there used to be
speculation about which colour will
Ben dye his hair next week, actually.
Here's some posters, Ben,
describing current work.
You'll find it interesting actually.
BEN LAUGHS
There you are. Coulomb blockade!
Oh, no! That's what I was doing.
That's what you were doing,
yeah, that's right.
I think you were the first in
the country to find those. I was.
That's what I did, this is my...
That's a quantum dot.
It's just been completely absorbed
into the way of doing things now,
so it's so long a discovery,
it's a diagnostic tool.
Really? It's part of the technology?
Yeah, it's part of... Use it for
diagnostics. Yeah, interesting, yeah.
Could've been me, Mike!
Your name should've been up there,
yeah. It could have been me!
Well, this'll bring back
some memories for you, Ben -
where you did your experiments.
'It was heartening to know
that my work at the lab
'had become part of
mainstream semiconductor research,
'but it wasn't going to help me
with my immediate problem.'
So, Mike, you've been a big help
in the past
when I've slightly lost my way.
I thought you'd be
a good person to talk to
at the beginning of my quest
to get to grips with one degree.
Erm...so I was wondering, really,
if you had any pointers
about what direction I should take?
That's a tough question
you've got there, Ben.
I mean, temperature
is a way of describing.
We must know temperature accurately,
we've got to know numbers accurately.
This is a question
about measurement, isn't it?
It's about how we...
Measurement is everything.
Measurement is everything.
I mean, if you don't feel
very well, you go to your GP.
The first thing that he or she
will do is measure your temperature
because they've got to know.
It's a measurement.
They've got to know what is going on
and that's the only way you can.
It's no good just saying,
"I'm hot, I'm cold."
You need to say, "How hot, how cold?"
So it's a big world out there, Ben,
so you've really got to dig around
for your answer, actually,
and I'm not sure I can help you that
much really beyond what I've said
and I wish you good luck!
And I'm intrigued to know
what you come up with.
Great! Spoken like
a true supervisor!
'The reality of the challenge I'd
set myself was beginning to sink in.
'There would be no easy answers.
'We all know the universe
contains some very, very hot things
'and some very, very cold things,
but what do they have in common?
'When we measure temperature,
what does it mean?
'With these kind of problems
in physics,
'I always find it helps
to return to basics,
'to get behind the thinking of
the great pioneers
'who first worked
on the idea of temperature.'
It's currently minus 196.7 degrees.
If you take a little step back.
Just to be extra cautious. Yeah.
'I knew that
for over a hundred years,
'the idea of going
beyond the human senses
'to find a scientifically reliable
measurement of temperature
'had been one of the great quests
driving forward science.'
You'll get an ice-cream headache
like you'd never believe. Brilliant!
'Over a nitrogen-cooled ice cream,
'Professor Hasok Chang promised to
show me a basic experiment
'that goes to the heart of
this simple,
'but most fundamental
of principles.'
BEN LAUGHS
It just feels so weird because I've
got my right hand in hot water,
my left hand in cold water.
What next?
Yeah, and now I want you to
take both of your hands out
and put them into the middle cup,
which has lukewarm water,
and tell me how that feels. OK.
Oh, my word!
The hand that was hot
now feels cold
and the hand that was cold
now feels hot.
Even though they're in
the same cup of water.
So this is how people realised
that our bodily sensations
didn't necessarily give
the right measure of temperature.
That's why you spend all your time,
that conversation
people always have indoors,
"Is it cold in here?
Is it hot in here?
"Is it cold, is it me, is it you?
"Is it me? Is it cold?
Is the door open? Is the heater on?"
If you're running a fever,
you're going to feel cold
and so people began to think
we can't rely on the body any more.
We need an instrument, a thermometer.
So they can now measure temperature,
but did they know what it was
that they were measuring?
Well, this was actually
a deep question
because when practical thermometry
as we know it was established -
which is late 18th century,
early 19th century -
the dominant conception of heat
was that it was a fluid,
which they called caloric.
A fluid? Yes. So many people
thought of temperature
as the density of this caloric fluid
that things possessed.
So they could measure temperature
long before they actually knew what
it was they were measuring?
Yes, and it took a long time
of very hard work in physics
before they could say
what temperature was.
Hasok, I've set myself
this challenge of finding out
what is one degree.
You've written a book on this.
What's the answer?
Well, Ben, it would be far too easy
if I just told you the answer.
Why don't you go
and make yourself a thermometer?
You know how
the basic principles work,
so go and rig one up,
come back to me
and we'll go
and make some measurements
and see what one degree really is.
Hasok! I bought you an ice cream!
What is it with you physicists?
BEN SIGHS
'When I asked Hasok to
help me define one degree,
'I thought I'd get
a neat and tidy answer.
'Instead, I now find myself
'returning to the very basics
of temperature measurement
'and surprisingly...
'..that actually feels good.'
You know, right now,
I've got exactly the same feeling
that I think I had when I turned up
at the Cavendish Laboratory
on the first day of my PhD.
This is what happens in science.
This is what happens in science.
You know, if you want
your bit of apparatus,
if you want to do your experiment,
if you want to...
investigate something,
it pretty much always starts
with making something.
'Galileo, Fahrenheit, Celsius...
'and now Miller.
'In my quest
to build a simple thermometer,
'I was following in the steps
'of some of the greatest names
in science.'
And you'll see... Wow!
'Will Floodgate of the British
Society Of Scientific Glassblowers
'had agreed to help me.'
Will, I'm trying to get
to the bottom of what is one degree
and I've been set the challenge
of building my own thermometer.
What do you have in mind? What's
your parameters that you've got?
You know, I can't help noticing
that most of the thermometers
you see around
basically involve
the expansion of a liquid
from a sort of bulb
up a very, very thin tube. Yeah.
So I thought I'd basically
go for that sort of design.
'I knew that if I could measure
the expansion of that liquid
'against a defined scale,
'I'd have a basic measurement
of temperature
'and the first step
towards defining one degree.
'But here's the tricky bit -
to measure that accurately,
'first you need to create
a bulb to hold the liquid,
'ideally without burning your lips.'
Oh, it's falling off!
Turn it, turn it.
WILL LAUGHS
Bring it in to your lips and blow
and keep it turning.
Blow. It's so difficult.
Where's the puff gone?
BEN GRUNTS
Oh, I'm getting it back! Good, good.
Blow, blow, blow! Blow...
and stop. You're going red.
Nothing happened.
Yes! It's getting there.
There's a tiny little bit of a bulb.
There's something in there.
I'm happy with that, that's great.
Ta-da! Wow!
It's a coalescing bulb.
Oh, that's fantastic!
That's beautiful!
That's the basics of a thermometer.
Here we go. We start to inject...
and the thing is,
this takes a little while.
'The first thermometers used water
'and it was only Fahrenheit,
in the early 18th century,
'who discovered
the accuracy of mercury.
'My choice would be somewhere
between the two - liquid alcohol.'
I don't believe it! That is
actually looking like a thermometer.
Yeah, you've got a thermometer there.
OK, so now,
to define my one degree,
I need two fixed points
of temperature,
two really reliable
fixed points of temperature -
one cold and one hot -
and then I divide that difference
up into 100 subdivisions
and one of those subdivisions is...
One degree. One degree.
'Without those two fixed points,
there would be no way
'to define a scale
'and no way of one thermometer
ever agreeing with another.'
Crushed ice. Lovely.
Oh, you beauty! Look at that.
That's my cold point.
So now I need to choose a hot point.
Do you ever make sandwiches here?
'The melting point of butter!
'Will assured me
I'd be in good company
'as it had been used by some of
the early pioneers of thermometry.'
Ooh, I've got it. Hot point...
..there - melting point of butter.
Cold point - melting point of ice.
Nice!
'I was now ready
to define my scale.'
OK, Will, so we've run into our
first snafu here, which is the...
the hot point on my scale is there
and the cold point is there,
so there's not a whole lot of space
to make my divisions into degrees,
so the melting point of ice
is going to be zero Millers
and the melting point of butter
is going to be five Millers. Great.
'I'd done everything
Hasok had asked.
'I'd built an accurate thermometer
'and defined my one degree
using two fixed points.
'I could now measure temperature
on the Miller scale.'
Hasok! Hello, Ben!
Have I got a treat for you!
Oh, have you done it? Yes, I have.
So what you have here...
this is the Miller scale.
Ah, the Miller scale.
Which is currently reading...
what are we at there?
1.25, I'd say, Millers.
No, what are the zero
and five points?
Well, zero is
the melting point of ice
and the five is
the melting point of butter. Butter?
Yeah. That's good, that's good.
Actually in 1688 there was a chap
called Dalence who made a thermometer
with the melting point of butter
as the upper point.
Oh, someone got there before me?
Yeah.
But I think you've got a problem
because, first of all,
no-one else is going to know
what the Miller scale means
if you gave numbers on that,
and if they were to try to make
the same thermometer as you did,
they're going to have to have
exactly the same butter as you used
because different butter
will melt at different temperatures.
Top marks for effort, but I'm afraid
you're not quite there yet.
Well, I don't feel my time's
been completely wasted,
because building this has given me
a really good...understanding
of the basic principles.
But what I still haven't got
is that scientific accuracy.
Ah, well,
the Miller scale is dead.
Yeah.
'I was realising
a great truth about one degree -
'that, ultimately, you can
define it in any way you like,
'but for it to be
scientifically meaningful,
'everyone has to agree to
the same system -
'a system I need to understand
if I'm going to
'get to the bottom
of what one degree really is.
'There was only
one place left to turn to -
'the National Physical
Laboratory in South London,
'where that 300-year-old
quest for scientific accuracy
'has been elevated into a religion.
'If one of my fixed points
is wildly inaccurate,
'I want to know
what the professionals use.
'Graham Machin and Michael
De Podesta promise to show me.'
Well, we have some in here, in
this container, some triple points.
The so-called triple points of water.
When you say triple points...
I can see there's like
crushed ice in here.
Yeah, OK so a triple point is where
a solid, a liquid
and the vapour of the same substance
are in equilibrium with each other.
'Graham explained to me that -
strange though it may sound -
'at the triple point, water is
present as liquid, ice and vapour,
'and that's only possible
at one unique temperature.'
So inside here now is only water.
There's water vapour.
Yeah. There's liquid water as
you can see and there's ice
and that's a unique temperature.
Just, just... Essentially,
it's really just up here.
Just at this point here
is the triple point of water -
the holy grail of thermometrists.
'Benchmarking your thermometer
to this unique fixed point
'gives you extraordinary precision
'and from that, in turn,
comes extraordinary accuracy.'
How accurate are they?
What would be the discrepancy?
How close do they agree?
Well, they're amazingly accurate.
Recently we compared some triple
point of water cells from NPL
with ones with
our colleagues across Europe
and they agreed
to within 20 millionths of a degree.
20 millionths?!
20 millionths of a degree.
Wow! Can I see one? Yes, of course.
There's one in this box here,
which I'll hold very carefully.
The very neat thing is that,
wherever you are in the world,
they all follow
the same temperature scale,
so whether you had this thermometer
calibrated here in the UK
or in the US or in Australia,
they will all... Or China.
Or China, they will all
realise the same temperature
to within a few millikelvin
or even slightly smaller than that.
'So much of what we take
for granted in temperature -
'being able to reliably know
that the medical thermometer
'that we measure
our child's fever with,
'or the food we buy
in the supermarket
'is kept at a controlled,
known, reliable temperature -
'that's really fundamental to
the way that our society operates'
and, you know, without this place,
life in contemporary Britain
would be as meaningless
as if everything was measured
on the Miller scale.
You know, I don't really feel
that I've completely got to grips
with what a degree is,
but I feel absolutely sure
that we can measure it.
'I finally feel
I'm making progress -
'that I'm getting back some of
my old physicist's knowhow -
'and at last I feel ready
to take my place alongside
the scientific community,
'to start making
my own measurements of temperature.
'To build a more accurate map
of Britain's variable weather,
'I knew the Met Office were
launching an initiative to encourage
'members of the public to submit
their own weather readings.'
Met Office string.
'They could count on my support.'
Whoa!
Look at that, look at that!
OK. Oh, this is the gold here.
"The instrument under test
was calibrated
"by direct comparison
against an SPRT thermometer
"having calibration
traceable to national standards
"immersed in a closely controlled
reference temperature environment.
"Readings were taken
with a viewing magnifier
"and the thermometer stem
was lightly tapped
prior to each reading.
"The following results
are derived from the mean average
of a number of repeat readings."
Accurate to within 0.02
degrees centigrade -
two HUNDREDTHS of a degree.
It's pretty accurate.
If I were to insert that rectally,
I would know your body temperature
to within 0.02 degrees centigrade.
That's good enough for me.
There we go, so...
..what we want is...maximum.
'I know I've got to put in the
hours, but I'm genuinely excited
'that data from this weather station
on my roof in the centre of London
'is going to be playing a small part
'in the British system of
temperature measurement.'
Wow! 27.2.
'But there's something
I still don't feel
'I've quite got to the bottom of.
'Yes, I might be able
'to measure one degree to an
incredible level of accuracy...
'..but measurement is one thing.
I still don't feel
'I can really describe what
one degree actually represents.
'It took the work of a Victorian
gentleman to open the door
'on the amazing world of what
temperature fundamentally is.
'James Joule wasn't a professional
scientist at all. He was a brewer.'
MECHANICAL RUMBLING
OK, so this is where the vats are.
Fantastic.
'Brewing requires a very careful
control of temperature
'and it turned Joule into
'a real master of accurate
temperature measurement.'
Whoa!
It's a beer fountain!
Just a sec.
BEN SLURPS
Yeah, it's coming on.
'True to the spirit of the age,
'Joule devised an experiment.
'Inspired by his brewer's knowhow,
Joule's simple experiment
'uses a falling weight
to churn up a container of water.
'He believed it would establish
something fundamental
'about what heat really is.'
It's a sort of rising excitement
you get when you do an experiment
when you've done
all the little fiddly bits
and suddenly you're
about to get an answer.
'According to Joule's theory,
'the experiment should cause the
temperature of the water to rise.
'If he was right,
'it would revolutionise
our understanding of temperature.'
The initial reading is 27.4, yeah.
Desperately imprecise,
of course, by Joule's standards.
He claimed to be able to read
to within one two-hundredth part
of a degree - and that's Fahrenheit.
I think... if you feel ready,
time for a boost.
I feel ready. Do you feel ready
for a boost? I feel ready. OK.
Come on, you beauty!
OK.
27.6,
27.7.
Any increase on 27.7?
I'd even go 27.75.
It's halfway between those
two marks, 27.75. Come on!
'Just over three-tenths of a degree,
'but for Joule
that proved something fundamental.'
So the motion of the paddles
has pushed the molecules of the
water around, made them go faster.
We're reading that...
as an increase in temperature.
We're reading that
as an increase in heat.
In other words,
heat itself is a type of motion.
Heat is a mode of motion,
that's what we think now.
That's what Joule thought then, at
a time when a lot of people didn't.
He uses the term "vis viva" -
Latin, means kind of vital force.
There wasn't even an English word
for this mysterious property
that people like Joule
said was conserved,
but the name that we
give to it now is "energy".
And the unit is now? And the unit of
energy in the SI system is the joule.
Mmm.
DANCE MUSIC THUMPS
'Energy.
'Here, at last, is the fundamental
entity I've been looking for -
'the thing that explains
what temperature really is.'
Whoa!
BEN LAUGHS
'And according to
Professor Jim Al-Khalili,
'apparently these dodgems
are the perfect place
to get to grips with it.'
Dodgems?
That's why I've brought you here.
You'd think it would be
quite random - I mean, it's fun -
but actually there's a
very serious analogy, a connection.
The way the dodgems bump into
each other, move around randomly,
is pretty much what goes on
down at the molecular level.
It's molecules behaving like dodgems,
bashing into each other,
and it's that movement - that energy
that the molecules have -
that defines what temperature is.
So heat is a form of energy?
Well, this is the profound thing.
Actually there's no such thing
as heat. What?!
You can do away with heat entirely.
There's no such thing as heat.
When something's temperature goes up,
something else is going on.
It's not about heat,
it's not about some sort of mystical
fluid being transferred around.
It's something going on
down at the molecular level
and that's what temperature
is all really about.
'So when its molecules
are moving slowly,
'a thing is at a lower temperature.
'And when they speed up,
the temperature's higher,
'and that, at its most basic,
is what temperature is.'
So when I look at
the thermometer on my roof,
basically... I mean,
that thermometer
is...burrowing right down
into the motion of the air molecules
around it? Yeah.
What it's measuring is
how energetic these air molecules are
bashing into the thermometer glass.
They're transferring that energy -
that momentum -
to the glass and then to the mercury,
and then the mercury atoms
are getting excited and vibrating
and that makes the mercury expand
and so you get a higher reading.
'So now we know -
'there's no such thing as heat.
'Instead, what matters is energy.'
It is a fundamental concept -
probably THE most fundamental concept
in physics -
but there are
different kinds of energy.
For me, energy is the ability...
to do something, to do work,
so, you know, if you have energy,
you can do stuff.
If you don't have any energy,
you don't do stuff
and that sort of applies all the
way down to the level of molecules.
I love the way that this subject -
this subject
of temperature and heat -
the further we dig down into it,
the bigger the mysteries
and the, kind of, the more
fundamental the... That's right.
I mean, you think you understand it
and then you realise there's
another hidden layer underneath
that sort of explains it,
but in another way makes it...
Well, for me, it makes it richer.
Some people might think "That just
makes it complicated.
"I'd much rather prefer
the simple transfer of heat,"
but you're getting down to
the nitty-gritty,
the real sort of nuts and bolts
of what it actually means.
'Mmm! I wonder how that distribution
of molecular energies is looking
in my thermometer this morning.'
Very light cloud.
Beautiful sunshine.
Present temperature is...
..16.2.
Maximum is...
20.5.
'The discovery that temperature
is simply an expression
of the energies of molecules
'led to a startling conclusion.
'If you cooled something
down so much
'that you completely
removed its energy,
'then that would be
the coldest you could go.
'They call this temperature
"absolute zero"
'and it's always fascinated me
'because as things get colder,
they also get stranger.'
This low-temperature physics
is kind of my home turf, you know.
It's...
It's where all sorts of weird
and wonderful stuff happens
and it's going to be emotional.
'I want to rediscover
the amazing things that happen
'when stuff gets so cold, its
molecules have virtually no energy.
'I'd come to one of
the world's leading
low-temperature laboratories -
'the Clarendon in Oxford - where
they promised they could show me.'
Good afternoon, gentlemen!
I brought you some flowers.
Cold things are different
to room-temperature things.
It's like a different world,
isn't it? Yes.
So everything is more...
is in a much lower energy state.
Very brittle.
'Professor Robert Taylor
'wanted to show me an experiment
that opens a door
'on what happens at
some of the coldest extremes
'of temperature
physically possible.'
So that's the nitrogen going in?
Yeah, we're going to
pre-cool the outside of the...
There's two jackets - an outside
jacket and an inside one.
That's right.
HISSING
As you cool things down,
they slow down.
Eventually, of course, they'll just
stop and when they stop, that's zero.
No motion, no temperature. Yes.
Has anyone ever got to zero?
No, you can't do it. Why not?
You can never get there. Why is that?
Because every time you try
and cool it down a little bit more,
you have to start again
and cool it down a bit more
and then you cool it
down a bit more
and you gradually get
closer and closer and closer,
but you never quite make it.
What's the closest
anyone's ever got?
Depends in which system
you're talking about.
In nuclear spins,
they got down to a nanokelvin,
which is ten to the minus nine -
that's nine zeros
after the decimal point.
That's a thousand millionth.
Thousand millionth of a...
Of a degree, above zero.
I'm just opening it ever
so slightly, like this? Yeah.
Oh, wow!
We're getting close to three kelvin.
Keep going, keep going. Still?
'Even if absolute zero
can't be reached,
'Robert promised
he could take me close,
'liquefying helium to temperatures
where our ordinary sense of reality
'is completely reversed.'
And as the pressure drops above the
helium, its temperature is dropping
and so eventually this
will drop down to about
2.17 degrees above absolute zero
and something magical happens there,
when it turns
from this normal kind of helium
into a helium called superfluid.
What happens then? It goes sort of
still? Yes, completely still, yeah.
Oh, wow! There it goes,
completely still.
It's gone completely still.
That is now sitting there at
2.17 degrees above absolute zero.
Wow, it's completely still,
no bubbles at all.
Because the entire liquid is
sitting at the same temperature.
And what am I looking at?
It doesn't look like
a liquid almost.
No, what's happening is that every
single atom in that helium liquid
is sitting there behaving in
what's called a co-operative state.
They're all behaving together so that
nowhere is a different temperature.
Everything is the same temperature
everywhere inside that liquid.
'As the helium atoms
turn into a superfluid
at that critical temperature,
'their fundamental
quantum nature asserts itself.
'Instead of individual atoms
bouncing around,
'the atoms move together
as if they were of one mind.'
OK, Ben, lift the bucket out
of there and see what happens.
Which one's the bucket? That one?
It's this one here. OK.
'Where normally the solid glass
bucket contains the liquid helium,
'once a superfluid, that very idea
that things are solid and
can be contained no longer holds.'
Watch the bottom of the bucket.
You see drips coming out and landing
on the surface of the liquid?
That's superfluid helium coming
through the bottom of that plug.
That plug held the ordinary helium,
but because this is superfluid,
it falls out of the bottom
and you can see the drips just coming
off and landing onto the surface.
You can see it pouring out.
'Now this is really strange.
'As a superfluid,
the liquid helium has no viscosity
'so instead of being held
by that solid plug,
'it now runs straight through it.'
It's a real quantum effect.
It's like a window on the world
of quantum mechanics. It is.
What an amazing thought that really,
this is what matter's really like.
All the stuff that we're made of,
this is what it's really like
and its real nature just gets
obscured at room temperature
because of all the vibration
and all the thermal energy.
This is really what we're made of.
We're made of weird stuff like this.
That is mind-blowing, isn't it?
It's also very cold.
That's at 2.17 kelvin
or 2.17 degrees above absolute zero
and that actually
is colder than outer space. (Wow.)
'You know, when I started
this journey, I was expecting'
to get to grips with something,
to approach through
accuracy and measurement
a real, knowable,
fundamental reality.
And actually, I've gone through
the rabbit hole and I've ended up...
somewhere I just never expected to
be and it's disturbing because...
..because what I've discovered
is that as temperature decreases,
as we get closer and closer
to absolute zero,
we pass into a completely
new world - the quantum world.
And it's baffling and it's weird
and temperature, you know, the
random thermal motion of molecules.
In a way, you can think
of it as being the thing...
..that obscures that weirdness
and makes our lives liveable.
Wow! Beautiful day!
Present temperature, 15.8.
Maximum, 17.7.
Minimum, 11.
I think it's going to be
a lot hotter than that today.
If you've just switched on,
I'm actually resetting
my maximum thermometer,
just in case you wondered!
'As I come up here every day
to make my measurements,
'I'm starting to see beyond those
simple numbers on my thermometer
'and I'm beginning to get a sense
of this deeper underlying entity -
'energy that ebbs and flows
through everything
'according to
the fundamental laws of physics.'
Very mild day, bit windy.
'And for the first time in 20 years,
it's made me reflect again
'on the vast role
energy plays in our universe,
'about where it comes from
and where it's going to.
'Professor Peter Atkins
of Oxford University
'had invited me to join him
in watching some films,
'with the promise he could
help answer my questions.'
I can't help noticing,
when I look around me, it's always
hot things that cool down.
You rarely see cool things
heating up of their own accord.
Yeah. And there's...
There's something really fundamental
going on there, isn't there? Yeah.
That is the most amazing insight
into the nature of things
going on in the world -
that things cool down -
because the energy that was
originally in this cup of coffee
is spreading into the surroundings.
So... And the insight
that you're talking about
is that effectively
things are getting worse.
If you're saying hot things
always cool down, your cup of coffee
always cools down...
Buildings fall down.
Buildings fall down, my desk gets
messier and messier at home.
Everything disperses.
Disorder drives the universe.
Collapse into disorder
is the spring of the universe.
Wow!
And I think it's fantastic
to know that this natural process
of energy spreading in disorder -
of matter, atoms, molecules
spreading in disorder -
is actually what drives every process
that happens in the world.
So the whole universe
is descending into disorder
and that's what
we can see on the screen.
You know, we don't see rubble
suddenly righting itself,
coming up to form a building.
All these processes,
we see that the amount of disorder
is always increasing.
That's a very
depressing thought, Peter!
Absolutely. And you should be
depressed because things...
The spring of change is that
the world is getting worse.
But it's getting worse in
an extraordinarily interesting way.
All processes on Earth -
the opening of a flower,
all the processes of the evolution
of the biosphere, for example -
are really just
elaborate manifestations
of this dispersal of energy.
Where is this going to end?
I mean...
Well, you can guess
where it's going to end -
when there's nowhere left
for more dispersal to take place.
Everything will be
at the same temperature.
Everything at the same temperature.
Yeah, there will be the heat death
of the universe.
'So everything is getting colder
and colder and colder.
'Bummer!
'Still, let's not get too depressed.
'The sun's still got enough fuel to
last us another four billion years.
'If only WE could replicate
some of that awesome power,
'we'd solve our own energy problems
at a stroke.
'To my amazement,
'there's a place where they're
actually trying to do just that.
'Tucked away
in the Oxfordshire countryside,
'the Joint European Torus
'is a project to try and create
nuclear fusion -
'the process that drives the sun.
'To succeed,
'they need to reach temperatures
at truly intimidating levels.'
Wow!
Jo, so how hot does it get in here?
It gets to about a hundred million
degrees centigrade.
BEN LAUGHS
A hundred million
degrees centigrade!
What's the temperature of the sun?
About 15 million degrees centigrade.
So of the order of ten times
the temperature of the sun.
That must be one of the hottest,
hottest things in this galaxy.
Why does it need to be that hot?
Well, we want to recreate
the process that fuels the sun
and that's the fusion of hydrogen
into helium,
and because hydrogen nuclei have
the same electric charge,
they repel each other
and to get them to fuse,
to join together,
we need to collide them
at really high speeds
and that's fundamentally
what temperature is.
It's a measure of the speed
that the particle is moving at.
Temperature is a measure of the
speed that molecules are moving at.
Yes, that's...
I'm really getting to grips
with that now.
'It's amazing to think that
'our control of temperature has
gone so far that we can actually
'think about replicating the process
that fuels the stars.
'To get the hydrogen
to such high speeds,
'they've built
a vast doughnut-shaped magnet
'just three metres across.
'So far they've only managed
to sustain the fusion reaction
'for just a few seconds.
'But for me, the possibility
of using science and technology
'to create a clean source of energy
'is one of the most exciting
ideas around.'
Wow!
It's like the set of an Eastern
European science-fiction film.
It is rather, isn't it? I love it!
Now I'm a bit of a temperature
measuring professional myself.
I don't want to
make a big deal about it,
but I've actually
made my own thermometer.
However, I'm pretty sure...
..my thermometer wouldn't cope
with a temperature
ten times the temperature
at the centre of the sun.
How do you measure
the temperature accurately?
How can you get an accurate measure
of a temperature that hot?
We actually have one physical device
that darts into the plasma
to measure right at the edge
where it's coolest.
It would actually be probably
a few million degrees,
but it darts in VERY quickly.
THEY LAUGH
Brilliant! What about
the middle, where...?
In the middle where it's
a hundred million, we have to
use laser-based techniques
to measure the temperature.
We shine a laser in and look
at the light that comes back.
And that gives you a really
accurate figure
without actually having to
touch the plasma.
Yes, the non-invasive technique.
Wow. Respect!
'I think, at last, I've got a sense
of what lies behind
'that simple measurement
of one degree on my thermometer.
'Going back to the woman
at the dinner party
who got me started on all this,
'I certainly feel I could have a
decent stab at explaining it to her.
'But her questions weren't
simply about that scientific idea -
'they were about what a temperature
rise of one degree means on average
'and that's where
things get a bit messy.
'I was back in Cambridge to meet
someone I hoped could help me.'
So I was having this conversation
and it became apparent
that she didn't really know
what an average was
so that when you might say, "The
average had increased by a degree,"
to her, that didn't really
sound very much
because every day the temperature
varies by much, much more than that,
and I slowly realised
I didn't really know
what an average was either -
sufficient to be
able to explain it -
and I thought you'd be
the right man to talk to.
OK, let's move away from temperature
and think about
another thing we can measure
like people's height.
So we talk about...
This is a scale of people's heights
and if we draw a curve like this...
where this shows sort of how many
people there are of each height.
So this is people of average height -
there's lots of them around -
and you've got short people down
here - there's a few of them -
and you've got really tall people
here and you've got a few of those.
So let's mark in
a really tall person.
So at the moment you've got that many
really tall people. Yeah.
So that may be 1 in 1,000,
1 in 10,000, something like that.
Six foot six. Something like that.
Let's say though that everyone grew
an inch, everyone got an inch taller.
Now what would happen is that
this distribution would shift...
..a little bit to the right. Yeah.
Round about the middle,
you wouldn't notice much at all.
If everyone in the street
was an inch taller,
I don't think you'd notice,
but if you're only looking at
really tall people,
now...
you've got a much bigger area.
The proportion of people who are
really tall has really gone up a lot.
If we put that into temperature,
that means that the days that are
really stinking hot in the past -
and they happen very rarely -
you only have to move
the mean temperature -
the average temperature - up a bit
and the number of those days
will really go up a lot.
In other words, if we're
talking about temperature,
say a rise of only a degree or so
in average temperature
will produce many more
very, very hot days? Yeah.
If we define a hot day
as something really uncomfortable,
if not dangerous - so very rare
at the moment -
those will become a lot less rare.
'As I've gone deeper into the
underlying science of temperature,
'one thing that's really stayed
with me is the value of measurement.
'Whether it's a million degrees...'
Oh, wow!
We're close to three kelvin.
'..a fraction
above absolute zero...'
That is mind-blowing, isn't it?
'..or taking readings
on my rooftop...
'..I've realised
that measuring temperature
'isn't simply a question
of fundamental physics.
'It matters to all of us.
'The Earth's average temperature
'has already increased by 0.75 of
a degree in the past 150 years
'and it's set to rise even further.
'That's why, for me, perhaps some of
the most interesting measurements
are taking place right here -
'in London W1.'
'Lift going up. Doors closing.
'The lift is now travelling
at 1,400 feet per minute.'
My ears have gone.
'Doors opening.'
'Dr Janet Barlow is one of
a new breed of meteorologists.'
Wow!
Fantastic, isn't it?
'She's managed to place her weather
station somewhere that's been closed
to the public for almost 30 years -
'on the top of the BT Tower,
191 metres above London.'
We've got the City
over to your right.
Over there. Oh, yeah, of course.
Brilliant!
You know, I'm really surprised
to know that
finding out what's going on
in terms of temperature in cities
is a new area.
Well, I think we've had a lot of
heat-wave events recently
and with concerns for the future,
we may get more heat waves,
but in cities
they're particularly intense
and we know from 2003,
many thousands of people died
in cities across Europe
because it was so hot,
so this is a real concern
for the future,
especially as cities like London
are going to expand
so those urban temperature effects
are only going to get worse.
I heard you had to
sneak up here to start with.
JANET LAUGHS
You think about things
in a very abstract way
and we had been thinking
for so long, "Wouldn't it be nice
"to get a temperature measurement, a
wind-speed measurement above London?"
And we just happened to be
walking out of a meeting
and there was the BT Tower
right in front of us.
So I thought, "Well,
you don't get if you don't ask,"
so I came and talked to
the security guards
and we came and made some
measurements within a few weeks.
'I really admire
scientists like Janet.
'She's investigating something
that ought to concern everyone
'because as cities like London
continue to grow,
'they're going to
keep getting hotter and hotter
'and that's without
even thinking about
'what climate change
will do to temperatures.'
So, Janet, this is like
a new frontier in temperature
measurement, isn't it?
You're right at the vanguard, doing
something no-one's done before.
Yeah, I mean, the BT Tower is
a really unique building in London.
It's so exposed to the atmosphere
compared to any other structure
that we have a really clear
idea of what's going on.
And from the initial results, having
a temperature measurement up here
compared to what we've got on the
ground, is giving us huge insight
into the way heat is carried
from the urban surface
up to the air above,
particularly at night-time when those
hot temperatures are occurring.
So going to show me your weather
station then? Oh, yes, of course.
BEN LAUGHS
How are you with heights, Janet?
I'm fine now, no problem.
UNCERTAINLY: Yeah.
Yeah, me too. Me too.
I'm great with heights, really good.
BEN MOUTHS
Whoa!
Wow!
Hang on,
where's your weather station?
It's up there.
Great, great...
Yeah, let's go up there -
that's going to be great(!)
That really is...
'I often complain about
health and safety,
'but for once I'm quite glad of it.
'To my relief,
they won't allow me up there.
'The weather station's data
is collected electronically,
'but for me to be able to
come up here and see this
'sums up everything about what makes
the science of temperature
'so fascinating
and so fundamental.'
So what does one degree,
what does that mean to you?
I think in the context of cities,
I'm looking at the difference between
the rural area and the city,
so, for example, how much bigger
does London have to get
to raise its temperature
by one degree?
That's a serious question
policy-makers are putting to us
and we have to do the calculations
and have the understanding
in order to answer it.
So after all this,
what is one degree?
To me, it represents
something so important
and that's measurement,
and that's why the woman
at the dinner party was so wrong
because we CAN know this stuff.
There's no arguing with measurement.
These things are fundamental.
And they reach right down
into the very roots of reality
and tell us unexpected, glorious,
confusing, odd, amazing,
sometimes unwelcome things.
Also one degree has
a personal meaning for me
because...I only got one degree.
Arguably, I should have
got another one as well,
but I didn't finish it
and I've always had a nagging
sense of guilt about that
and I feel that, just maybe,
on this journey,
I've paid...a small fraction
of that guilt off.
Not very much,
maybe just one degree.
PHONE RINGS
Coming!
Hello?
Hi, yeah, James, hello.
Yes, yes,
of course I've seen Avatar.
Yeah, I'd absolutely love to,
but I've got this weather station
on my roof, yes.
I have to take measurements
every morning,
so I'm afraid it's a no-show.
PHONE RINGS
Hello?
Where am I? James, I told you,
I can't make it. I can't come.
No, no, no,
I've got this weather station.
Yeah, remember,
regular measurements? Yeah.
Tell you what, try Rob Brydon.
'I'm a comedian, but for six years
I was a physicist.'
Wow!
'Something really embarrassing
happened to me recently.
'Someone asked me what seemed like
a basic scientific question,
'something that should have been
second nature
'to someone with my background.
'They wanted to know about
temperature.'
Glorious.
That's 19 degrees.
'And try as I might,
I couldn't answer them,
'so I've decided to go on
a physics refresher course...'
Wow!
'..to investigate
the secrets of temperature.'
Oh, you beauty. Look at that.
My life has purpose again!
BEN LAUGHS
I feel like, er...
I feel like I'm actually
doing something useful.
'One degree might seem like the most
basic of concepts, but actually,
'the more you delve into it,
the deeper...'
That is mind-blowing! Look!
It's also very cold.
I've gone through the rabbit hole
and I've ended up
somewhere I just never
expected to be and it's disturbing.
'..the stranger...'
So heat is a form of energy.
Well, this is the profound thing.
Actually, there's no such thing
as heat. What?!
'..and the more surprising
temperature becomes.'
So going to show me your weather
station then? Oh, yes. Of course.
'So I need an answer.
'What is one degree?'
Er, how's it going?
Portion of chips, please.
'Most of us don't give much thought
to the question of temperature,
'to the difference between
'say an ice cream
at minus 16 degrees Celsius...
'..and a cup of tea at 82.
'But for me, behind these
apparently simple questions
'lurk some of the deepest, most
fundamental scientific mysteries
'in all of nature.'
You know, recently I've been
thinking a lot about temperature.
I was at this dinner party
and I was sitting opposite a woman
and we started
talking about climate change
and I was saying to her how
the planet's temperature's increased
and she was disagreeing with me,
saying, "No, it hasn't.
"They don't know that for sure."
And the more I tried to explain
about temperature and what it was
and how we could definitely measure
it, the more I started struggling.
And then I started thinking,
"Hang on, I used to be a physicist.
"If I can't explain this stuff,
who can?"
'There's no getting away from it.
I couldn't answer her
'and that's why I've decided to
return to my roots as a physicist
'to find out what one degree
really is.'
I've been thinking
about one degree...
and I'm beginning to get
a familiar feeling
that I used to have,
studying physics,
which is you kind of...
You start out with something
that seems very simple,
that you just want to define
in a straightforward way -
something like temperature -
and the more you think about it...
..the deeper the layers get and the
less you feel you really understand.
You know, this really
isn't going to be easy for me
because I can't remember, really,
in detail, anything that I studied.
"Novel quantum effects
in low temperature, mesoscopic,
"quasi-zero-dimensional
electron systems."
Yep, that was the title of the PhD
I embarked on here in Cambridge
after completing my physics degree.
You know, this is a really fitting
place to be starting this journey
because this is where...
I mean, this is where modern
physics started really.
This is the spiritual home of
physics - the Cavendish Laboratory.
This is where everything happened -
Ernest Rutherford split the atom,
JJ Thomson discovered the electron,
GI Taylor discovered
the quantum nature of light.
It all happened here.
It's where Ben Miller
studied for his PhD.
Aaargh!
'After 20 away from the lab,
I knew I'd need help.
'I decided to look up
my old supervisor...'
The prodigal returns!
'..the leading
semiconductor physicist
Professor Sir Mike Pepper.
'Mike was always the guy you went
to to put you on the right track.
'Mike has a brilliant way of
being able to
'explain complex ideas
really, really clearly,
'and just with a few words,
'he would just kind of
put you back on the beaten track.'
A couple of photographs here
with you on them. Right, yes.
The lab photos, the hall of fame.
There I am.
That's it. With bleached-blond hair.
Yeah, there used to be
speculation about which colour will
Ben dye his hair next week, actually.
Here's some posters, Ben,
describing current work.
You'll find it interesting actually.
BEN LAUGHS
There you are. Coulomb blockade!
Oh, no! That's what I was doing.
That's what you were doing,
yeah, that's right.
I think you were the first in
the country to find those. I was.
That's what I did, this is my...
That's a quantum dot.
It's just been completely absorbed
into the way of doing things now,
so it's so long a discovery,
it's a diagnostic tool.
Really? It's part of the technology?
Yeah, it's part of... Use it for
diagnostics. Yeah, interesting, yeah.
Could've been me, Mike!
Your name should've been up there,
yeah. It could have been me!
Well, this'll bring back
some memories for you, Ben -
where you did your experiments.
'It was heartening to know
that my work at the lab
'had become part of
mainstream semiconductor research,
'but it wasn't going to help me
with my immediate problem.'
So, Mike, you've been a big help
in the past
when I've slightly lost my way.
I thought you'd be
a good person to talk to
at the beginning of my quest
to get to grips with one degree.
Erm...so I was wondering, really,
if you had any pointers
about what direction I should take?
That's a tough question
you've got there, Ben.
I mean, temperature
is a way of describing.
We must know temperature accurately,
we've got to know numbers accurately.
This is a question
about measurement, isn't it?
It's about how we...
Measurement is everything.
Measurement is everything.
I mean, if you don't feel
very well, you go to your GP.
The first thing that he or she
will do is measure your temperature
because they've got to know.
It's a measurement.
They've got to know what is going on
and that's the only way you can.
It's no good just saying,
"I'm hot, I'm cold."
You need to say, "How hot, how cold?"
So it's a big world out there, Ben,
so you've really got to dig around
for your answer, actually,
and I'm not sure I can help you that
much really beyond what I've said
and I wish you good luck!
And I'm intrigued to know
what you come up with.
Great! Spoken like
a true supervisor!
'The reality of the challenge I'd
set myself was beginning to sink in.
'There would be no easy answers.
'We all know the universe
contains some very, very hot things
'and some very, very cold things,
but what do they have in common?
'When we measure temperature,
what does it mean?
'With these kind of problems
in physics,
'I always find it helps
to return to basics,
'to get behind the thinking of
the great pioneers
'who first worked
on the idea of temperature.'
It's currently minus 196.7 degrees.
If you take a little step back.
Just to be extra cautious. Yeah.
'I knew that
for over a hundred years,
'the idea of going
beyond the human senses
'to find a scientifically reliable
measurement of temperature
'had been one of the great quests
driving forward science.'
You'll get an ice-cream headache
like you'd never believe. Brilliant!
'Over a nitrogen-cooled ice cream,
'Professor Hasok Chang promised to
show me a basic experiment
'that goes to the heart of
this simple,
'but most fundamental
of principles.'
BEN LAUGHS
It just feels so weird because I've
got my right hand in hot water,
my left hand in cold water.
What next?
Yeah, and now I want you to
take both of your hands out
and put them into the middle cup,
which has lukewarm water,
and tell me how that feels. OK.
Oh, my word!
The hand that was hot
now feels cold
and the hand that was cold
now feels hot.
Even though they're in
the same cup of water.
So this is how people realised
that our bodily sensations
didn't necessarily give
the right measure of temperature.
That's why you spend all your time,
that conversation
people always have indoors,
"Is it cold in here?
Is it hot in here?
"Is it cold, is it me, is it you?
"Is it me? Is it cold?
Is the door open? Is the heater on?"
If you're running a fever,
you're going to feel cold
and so people began to think
we can't rely on the body any more.
We need an instrument, a thermometer.
So they can now measure temperature,
but did they know what it was
that they were measuring?
Well, this was actually
a deep question
because when practical thermometry
as we know it was established -
which is late 18th century,
early 19th century -
the dominant conception of heat
was that it was a fluid,
which they called caloric.
A fluid? Yes. So many people
thought of temperature
as the density of this caloric fluid
that things possessed.
So they could measure temperature
long before they actually knew what
it was they were measuring?
Yes, and it took a long time
of very hard work in physics
before they could say
what temperature was.
Hasok, I've set myself
this challenge of finding out
what is one degree.
You've written a book on this.
What's the answer?
Well, Ben, it would be far too easy
if I just told you the answer.
Why don't you go
and make yourself a thermometer?
You know how
the basic principles work,
so go and rig one up,
come back to me
and we'll go
and make some measurements
and see what one degree really is.
Hasok! I bought you an ice cream!
What is it with you physicists?
BEN SIGHS
'When I asked Hasok to
help me define one degree,
'I thought I'd get
a neat and tidy answer.
'Instead, I now find myself
'returning to the very basics
of temperature measurement
'and surprisingly...
'..that actually feels good.'
You know, right now,
I've got exactly the same feeling
that I think I had when I turned up
at the Cavendish Laboratory
on the first day of my PhD.
This is what happens in science.
This is what happens in science.
You know, if you want
your bit of apparatus,
if you want to do your experiment,
if you want to...
investigate something,
it pretty much always starts
with making something.
'Galileo, Fahrenheit, Celsius...
'and now Miller.
'In my quest
to build a simple thermometer,
'I was following in the steps
'of some of the greatest names
in science.'
And you'll see... Wow!
'Will Floodgate of the British
Society Of Scientific Glassblowers
'had agreed to help me.'
Will, I'm trying to get
to the bottom of what is one degree
and I've been set the challenge
of building my own thermometer.
What do you have in mind? What's
your parameters that you've got?
You know, I can't help noticing
that most of the thermometers
you see around
basically involve
the expansion of a liquid
from a sort of bulb
up a very, very thin tube. Yeah.
So I thought I'd basically
go for that sort of design.
'I knew that if I could measure
the expansion of that liquid
'against a defined scale,
'I'd have a basic measurement
of temperature
'and the first step
towards defining one degree.
'But here's the tricky bit -
to measure that accurately,
'first you need to create
a bulb to hold the liquid,
'ideally without burning your lips.'
Oh, it's falling off!
Turn it, turn it.
WILL LAUGHS
Bring it in to your lips and blow
and keep it turning.
Blow. It's so difficult.
Where's the puff gone?
BEN GRUNTS
Oh, I'm getting it back! Good, good.
Blow, blow, blow! Blow...
and stop. You're going red.
Nothing happened.
Yes! It's getting there.
There's a tiny little bit of a bulb.
There's something in there.
I'm happy with that, that's great.
Ta-da! Wow!
It's a coalescing bulb.
Oh, that's fantastic!
That's beautiful!
That's the basics of a thermometer.
Here we go. We start to inject...
and the thing is,
this takes a little while.
'The first thermometers used water
'and it was only Fahrenheit,
in the early 18th century,
'who discovered
the accuracy of mercury.
'My choice would be somewhere
between the two - liquid alcohol.'
I don't believe it! That is
actually looking like a thermometer.
Yeah, you've got a thermometer there.
OK, so now,
to define my one degree,
I need two fixed points
of temperature,
two really reliable
fixed points of temperature -
one cold and one hot -
and then I divide that difference
up into 100 subdivisions
and one of those subdivisions is...
One degree. One degree.
'Without those two fixed points,
there would be no way
'to define a scale
'and no way of one thermometer
ever agreeing with another.'
Crushed ice. Lovely.
Oh, you beauty! Look at that.
That's my cold point.
So now I need to choose a hot point.
Do you ever make sandwiches here?
'The melting point of butter!
'Will assured me
I'd be in good company
'as it had been used by some of
the early pioneers of thermometry.'
Ooh, I've got it. Hot point...
..there - melting point of butter.
Cold point - melting point of ice.
Nice!
'I was now ready
to define my scale.'
OK, Will, so we've run into our
first snafu here, which is the...
the hot point on my scale is there
and the cold point is there,
so there's not a whole lot of space
to make my divisions into degrees,
so the melting point of ice
is going to be zero Millers
and the melting point of butter
is going to be five Millers. Great.
'I'd done everything
Hasok had asked.
'I'd built an accurate thermometer
'and defined my one degree
using two fixed points.
'I could now measure temperature
on the Miller scale.'
Hasok! Hello, Ben!
Have I got a treat for you!
Oh, have you done it? Yes, I have.
So what you have here...
this is the Miller scale.
Ah, the Miller scale.
Which is currently reading...
what are we at there?
1.25, I'd say, Millers.
No, what are the zero
and five points?
Well, zero is
the melting point of ice
and the five is
the melting point of butter. Butter?
Yeah. That's good, that's good.
Actually in 1688 there was a chap
called Dalence who made a thermometer
with the melting point of butter
as the upper point.
Oh, someone got there before me?
Yeah.
But I think you've got a problem
because, first of all,
no-one else is going to know
what the Miller scale means
if you gave numbers on that,
and if they were to try to make
the same thermometer as you did,
they're going to have to have
exactly the same butter as you used
because different butter
will melt at different temperatures.
Top marks for effort, but I'm afraid
you're not quite there yet.
Well, I don't feel my time's
been completely wasted,
because building this has given me
a really good...understanding
of the basic principles.
But what I still haven't got
is that scientific accuracy.
Ah, well,
the Miller scale is dead.
Yeah.
'I was realising
a great truth about one degree -
'that, ultimately, you can
define it in any way you like,
'but for it to be
scientifically meaningful,
'everyone has to agree to
the same system -
'a system I need to understand
if I'm going to
'get to the bottom
of what one degree really is.
'There was only
one place left to turn to -
'the National Physical
Laboratory in South London,
'where that 300-year-old
quest for scientific accuracy
'has been elevated into a religion.
'If one of my fixed points
is wildly inaccurate,
'I want to know
what the professionals use.
'Graham Machin and Michael
De Podesta promise to show me.'
Well, we have some in here, in
this container, some triple points.
The so-called triple points of water.
When you say triple points...
I can see there's like
crushed ice in here.
Yeah, OK so a triple point is where
a solid, a liquid
and the vapour of the same substance
are in equilibrium with each other.
'Graham explained to me that -
strange though it may sound -
'at the triple point, water is
present as liquid, ice and vapour,
'and that's only possible
at one unique temperature.'
So inside here now is only water.
There's water vapour.
Yeah. There's liquid water as
you can see and there's ice
and that's a unique temperature.
Just, just... Essentially,
it's really just up here.
Just at this point here
is the triple point of water -
the holy grail of thermometrists.
'Benchmarking your thermometer
to this unique fixed point
'gives you extraordinary precision
'and from that, in turn,
comes extraordinary accuracy.'
How accurate are they?
What would be the discrepancy?
How close do they agree?
Well, they're amazingly accurate.
Recently we compared some triple
point of water cells from NPL
with ones with
our colleagues across Europe
and they agreed
to within 20 millionths of a degree.
20 millionths?!
20 millionths of a degree.
Wow! Can I see one? Yes, of course.
There's one in this box here,
which I'll hold very carefully.
The very neat thing is that,
wherever you are in the world,
they all follow
the same temperature scale,
so whether you had this thermometer
calibrated here in the UK
or in the US or in Australia,
they will all... Or China.
Or China, they will all
realise the same temperature
to within a few millikelvin
or even slightly smaller than that.
'So much of what we take
for granted in temperature -
'being able to reliably know
that the medical thermometer
'that we measure
our child's fever with,
'or the food we buy
in the supermarket
'is kept at a controlled,
known, reliable temperature -
'that's really fundamental to
the way that our society operates'
and, you know, without this place,
life in contemporary Britain
would be as meaningless
as if everything was measured
on the Miller scale.
You know, I don't really feel
that I've completely got to grips
with what a degree is,
but I feel absolutely sure
that we can measure it.
'I finally feel
I'm making progress -
'that I'm getting back some of
my old physicist's knowhow -
'and at last I feel ready
to take my place alongside
the scientific community,
'to start making
my own measurements of temperature.
'To build a more accurate map
of Britain's variable weather,
'I knew the Met Office were
launching an initiative to encourage
'members of the public to submit
their own weather readings.'
Met Office string.
'They could count on my support.'
Whoa!
Look at that, look at that!
OK. Oh, this is the gold here.
"The instrument under test
was calibrated
"by direct comparison
against an SPRT thermometer
"having calibration
traceable to national standards
"immersed in a closely controlled
reference temperature environment.
"Readings were taken
with a viewing magnifier
"and the thermometer stem
was lightly tapped
prior to each reading.
"The following results
are derived from the mean average
of a number of repeat readings."
Accurate to within 0.02
degrees centigrade -
two HUNDREDTHS of a degree.
It's pretty accurate.
If I were to insert that rectally,
I would know your body temperature
to within 0.02 degrees centigrade.
That's good enough for me.
There we go, so...
..what we want is...maximum.
'I know I've got to put in the
hours, but I'm genuinely excited
'that data from this weather station
on my roof in the centre of London
'is going to be playing a small part
'in the British system of
temperature measurement.'
Wow! 27.2.
'But there's something
I still don't feel
'I've quite got to the bottom of.
'Yes, I might be able
'to measure one degree to an
incredible level of accuracy...
'..but measurement is one thing.
I still don't feel
'I can really describe what
one degree actually represents.
'It took the work of a Victorian
gentleman to open the door
'on the amazing world of what
temperature fundamentally is.
'James Joule wasn't a professional
scientist at all. He was a brewer.'
MECHANICAL RUMBLING
OK, so this is where the vats are.
Fantastic.
'Brewing requires a very careful
control of temperature
'and it turned Joule into
'a real master of accurate
temperature measurement.'
Whoa!
It's a beer fountain!
Just a sec.
BEN SLURPS
Yeah, it's coming on.
'True to the spirit of the age,
'Joule devised an experiment.
'Inspired by his brewer's knowhow,
Joule's simple experiment
'uses a falling weight
to churn up a container of water.
'He believed it would establish
something fundamental
'about what heat really is.'
It's a sort of rising excitement
you get when you do an experiment
when you've done
all the little fiddly bits
and suddenly you're
about to get an answer.
'According to Joule's theory,
'the experiment should cause the
temperature of the water to rise.
'If he was right,
'it would revolutionise
our understanding of temperature.'
The initial reading is 27.4, yeah.
Desperately imprecise,
of course, by Joule's standards.
He claimed to be able to read
to within one two-hundredth part
of a degree - and that's Fahrenheit.
I think... if you feel ready,
time for a boost.
I feel ready. Do you feel ready
for a boost? I feel ready. OK.
Come on, you beauty!
OK.
27.6,
27.7.
Any increase on 27.7?
I'd even go 27.75.
It's halfway between those
two marks, 27.75. Come on!
'Just over three-tenths of a degree,
'but for Joule
that proved something fundamental.'
So the motion of the paddles
has pushed the molecules of the
water around, made them go faster.
We're reading that...
as an increase in temperature.
We're reading that
as an increase in heat.
In other words,
heat itself is a type of motion.
Heat is a mode of motion,
that's what we think now.
That's what Joule thought then, at
a time when a lot of people didn't.
He uses the term "vis viva" -
Latin, means kind of vital force.
There wasn't even an English word
for this mysterious property
that people like Joule
said was conserved,
but the name that we
give to it now is "energy".
And the unit is now? And the unit of
energy in the SI system is the joule.
Mmm.
DANCE MUSIC THUMPS
'Energy.
'Here, at last, is the fundamental
entity I've been looking for -
'the thing that explains
what temperature really is.'
Whoa!
BEN LAUGHS
'And according to
Professor Jim Al-Khalili,
'apparently these dodgems
are the perfect place
to get to grips with it.'
Dodgems?
That's why I've brought you here.
You'd think it would be
quite random - I mean, it's fun -
but actually there's a
very serious analogy, a connection.
The way the dodgems bump into
each other, move around randomly,
is pretty much what goes on
down at the molecular level.
It's molecules behaving like dodgems,
bashing into each other,
and it's that movement - that energy
that the molecules have -
that defines what temperature is.
So heat is a form of energy?
Well, this is the profound thing.
Actually there's no such thing
as heat. What?!
You can do away with heat entirely.
There's no such thing as heat.
When something's temperature goes up,
something else is going on.
It's not about heat,
it's not about some sort of mystical
fluid being transferred around.
It's something going on
down at the molecular level
and that's what temperature
is all really about.
'So when its molecules
are moving slowly,
'a thing is at a lower temperature.
'And when they speed up,
the temperature's higher,
'and that, at its most basic,
is what temperature is.'
So when I look at
the thermometer on my roof,
basically... I mean,
that thermometer
is...burrowing right down
into the motion of the air molecules
around it? Yeah.
What it's measuring is
how energetic these air molecules are
bashing into the thermometer glass.
They're transferring that energy -
that momentum -
to the glass and then to the mercury,
and then the mercury atoms
are getting excited and vibrating
and that makes the mercury expand
and so you get a higher reading.
'So now we know -
'there's no such thing as heat.
'Instead, what matters is energy.'
It is a fundamental concept -
probably THE most fundamental concept
in physics -
but there are
different kinds of energy.
For me, energy is the ability...
to do something, to do work,
so, you know, if you have energy,
you can do stuff.
If you don't have any energy,
you don't do stuff
and that sort of applies all the
way down to the level of molecules.
I love the way that this subject -
this subject
of temperature and heat -
the further we dig down into it,
the bigger the mysteries
and the, kind of, the more
fundamental the... That's right.
I mean, you think you understand it
and then you realise there's
another hidden layer underneath
that sort of explains it,
but in another way makes it...
Well, for me, it makes it richer.
Some people might think "That just
makes it complicated.
"I'd much rather prefer
the simple transfer of heat,"
but you're getting down to
the nitty-gritty,
the real sort of nuts and bolts
of what it actually means.
'Mmm! I wonder how that distribution
of molecular energies is looking
in my thermometer this morning.'
Very light cloud.
Beautiful sunshine.
Present temperature is...
..16.2.
Maximum is...
20.5.
'The discovery that temperature
is simply an expression
of the energies of molecules
'led to a startling conclusion.
'If you cooled something
down so much
'that you completely
removed its energy,
'then that would be
the coldest you could go.
'They call this temperature
"absolute zero"
'and it's always fascinated me
'because as things get colder,
they also get stranger.'
This low-temperature physics
is kind of my home turf, you know.
It's...
It's where all sorts of weird
and wonderful stuff happens
and it's going to be emotional.
'I want to rediscover
the amazing things that happen
'when stuff gets so cold, its
molecules have virtually no energy.
'I'd come to one of
the world's leading
low-temperature laboratories -
'the Clarendon in Oxford - where
they promised they could show me.'
Good afternoon, gentlemen!
I brought you some flowers.
Cold things are different
to room-temperature things.
It's like a different world,
isn't it? Yes.
So everything is more...
is in a much lower energy state.
Very brittle.
'Professor Robert Taylor
'wanted to show me an experiment
that opens a door
'on what happens at
some of the coldest extremes
'of temperature
physically possible.'
So that's the nitrogen going in?
Yeah, we're going to
pre-cool the outside of the...
There's two jackets - an outside
jacket and an inside one.
That's right.
HISSING
As you cool things down,
they slow down.
Eventually, of course, they'll just
stop and when they stop, that's zero.
No motion, no temperature. Yes.
Has anyone ever got to zero?
No, you can't do it. Why not?
You can never get there. Why is that?
Because every time you try
and cool it down a little bit more,
you have to start again
and cool it down a bit more
and then you cool it
down a bit more
and you gradually get
closer and closer and closer,
but you never quite make it.
What's the closest
anyone's ever got?
Depends in which system
you're talking about.
In nuclear spins,
they got down to a nanokelvin,
which is ten to the minus nine -
that's nine zeros
after the decimal point.
That's a thousand millionth.
Thousand millionth of a...
Of a degree, above zero.
I'm just opening it ever
so slightly, like this? Yeah.
Oh, wow!
We're getting close to three kelvin.
Keep going, keep going. Still?
'Even if absolute zero
can't be reached,
'Robert promised
he could take me close,
'liquefying helium to temperatures
where our ordinary sense of reality
'is completely reversed.'
And as the pressure drops above the
helium, its temperature is dropping
and so eventually this
will drop down to about
2.17 degrees above absolute zero
and something magical happens there,
when it turns
from this normal kind of helium
into a helium called superfluid.
What happens then? It goes sort of
still? Yes, completely still, yeah.
Oh, wow! There it goes,
completely still.
It's gone completely still.
That is now sitting there at
2.17 degrees above absolute zero.
Wow, it's completely still,
no bubbles at all.
Because the entire liquid is
sitting at the same temperature.
And what am I looking at?
It doesn't look like
a liquid almost.
No, what's happening is that every
single atom in that helium liquid
is sitting there behaving in
what's called a co-operative state.
They're all behaving together so that
nowhere is a different temperature.
Everything is the same temperature
everywhere inside that liquid.
'As the helium atoms
turn into a superfluid
at that critical temperature,
'their fundamental
quantum nature asserts itself.
'Instead of individual atoms
bouncing around,
'the atoms move together
as if they were of one mind.'
OK, Ben, lift the bucket out
of there and see what happens.
Which one's the bucket? That one?
It's this one here. OK.
'Where normally the solid glass
bucket contains the liquid helium,
'once a superfluid, that very idea
that things are solid and
can be contained no longer holds.'
Watch the bottom of the bucket.
You see drips coming out and landing
on the surface of the liquid?
That's superfluid helium coming
through the bottom of that plug.
That plug held the ordinary helium,
but because this is superfluid,
it falls out of the bottom
and you can see the drips just coming
off and landing onto the surface.
You can see it pouring out.
'Now this is really strange.
'As a superfluid,
the liquid helium has no viscosity
'so instead of being held
by that solid plug,
'it now runs straight through it.'
It's a real quantum effect.
It's like a window on the world
of quantum mechanics. It is.
What an amazing thought that really,
this is what matter's really like.
All the stuff that we're made of,
this is what it's really like
and its real nature just gets
obscured at room temperature
because of all the vibration
and all the thermal energy.
This is really what we're made of.
We're made of weird stuff like this.
That is mind-blowing, isn't it?
It's also very cold.
That's at 2.17 kelvin
or 2.17 degrees above absolute zero
and that actually
is colder than outer space. (Wow.)
'You know, when I started
this journey, I was expecting'
to get to grips with something,
to approach through
accuracy and measurement
a real, knowable,
fundamental reality.
And actually, I've gone through
the rabbit hole and I've ended up...
somewhere I just never expected to
be and it's disturbing because...
..because what I've discovered
is that as temperature decreases,
as we get closer and closer
to absolute zero,
we pass into a completely
new world - the quantum world.
And it's baffling and it's weird
and temperature, you know, the
random thermal motion of molecules.
In a way, you can think
of it as being the thing...
..that obscures that weirdness
and makes our lives liveable.
Wow! Beautiful day!
Present temperature, 15.8.
Maximum, 17.7.
Minimum, 11.
I think it's going to be
a lot hotter than that today.
If you've just switched on,
I'm actually resetting
my maximum thermometer,
just in case you wondered!
'As I come up here every day
to make my measurements,
'I'm starting to see beyond those
simple numbers on my thermometer
'and I'm beginning to get a sense
of this deeper underlying entity -
'energy that ebbs and flows
through everything
'according to
the fundamental laws of physics.'
Very mild day, bit windy.
'And for the first time in 20 years,
it's made me reflect again
'on the vast role
energy plays in our universe,
'about where it comes from
and where it's going to.
'Professor Peter Atkins
of Oxford University
'had invited me to join him
in watching some films,
'with the promise he could
help answer my questions.'
I can't help noticing,
when I look around me, it's always
hot things that cool down.
You rarely see cool things
heating up of their own accord.
Yeah. And there's...
There's something really fundamental
going on there, isn't there? Yeah.
That is the most amazing insight
into the nature of things
going on in the world -
that things cool down -
because the energy that was
originally in this cup of coffee
is spreading into the surroundings.
So... And the insight
that you're talking about
is that effectively
things are getting worse.
If you're saying hot things
always cool down, your cup of coffee
always cools down...
Buildings fall down.
Buildings fall down, my desk gets
messier and messier at home.
Everything disperses.
Disorder drives the universe.
Collapse into disorder
is the spring of the universe.
Wow!
And I think it's fantastic
to know that this natural process
of energy spreading in disorder -
of matter, atoms, molecules
spreading in disorder -
is actually what drives every process
that happens in the world.
So the whole universe
is descending into disorder
and that's what
we can see on the screen.
You know, we don't see rubble
suddenly righting itself,
coming up to form a building.
All these processes,
we see that the amount of disorder
is always increasing.
That's a very
depressing thought, Peter!
Absolutely. And you should be
depressed because things...
The spring of change is that
the world is getting worse.
But it's getting worse in
an extraordinarily interesting way.
All processes on Earth -
the opening of a flower,
all the processes of the evolution
of the biosphere, for example -
are really just
elaborate manifestations
of this dispersal of energy.
Where is this going to end?
I mean...
Well, you can guess
where it's going to end -
when there's nowhere left
for more dispersal to take place.
Everything will be
at the same temperature.
Everything at the same temperature.
Yeah, there will be the heat death
of the universe.
'So everything is getting colder
and colder and colder.
'Bummer!
'Still, let's not get too depressed.
'The sun's still got enough fuel to
last us another four billion years.
'If only WE could replicate
some of that awesome power,
'we'd solve our own energy problems
at a stroke.
'To my amazement,
'there's a place where they're
actually trying to do just that.
'Tucked away
in the Oxfordshire countryside,
'the Joint European Torus
'is a project to try and create
nuclear fusion -
'the process that drives the sun.
'To succeed,
'they need to reach temperatures
at truly intimidating levels.'
Wow!
Jo, so how hot does it get in here?
It gets to about a hundred million
degrees centigrade.
BEN LAUGHS
A hundred million
degrees centigrade!
What's the temperature of the sun?
About 15 million degrees centigrade.
So of the order of ten times
the temperature of the sun.
That must be one of the hottest,
hottest things in this galaxy.
Why does it need to be that hot?
Well, we want to recreate
the process that fuels the sun
and that's the fusion of hydrogen
into helium,
and because hydrogen nuclei have
the same electric charge,
they repel each other
and to get them to fuse,
to join together,
we need to collide them
at really high speeds
and that's fundamentally
what temperature is.
It's a measure of the speed
that the particle is moving at.
Temperature is a measure of the
speed that molecules are moving at.
Yes, that's...
I'm really getting to grips
with that now.
'It's amazing to think that
'our control of temperature has
gone so far that we can actually
'think about replicating the process
that fuels the stars.
'To get the hydrogen
to such high speeds,
'they've built
a vast doughnut-shaped magnet
'just three metres across.
'So far they've only managed
to sustain the fusion reaction
'for just a few seconds.
'But for me, the possibility
of using science and technology
'to create a clean source of energy
'is one of the most exciting
ideas around.'
Wow!
It's like the set of an Eastern
European science-fiction film.
It is rather, isn't it? I love it!
Now I'm a bit of a temperature
measuring professional myself.
I don't want to
make a big deal about it,
but I've actually
made my own thermometer.
However, I'm pretty sure...
..my thermometer wouldn't cope
with a temperature
ten times the temperature
at the centre of the sun.
How do you measure
the temperature accurately?
How can you get an accurate measure
of a temperature that hot?
We actually have one physical device
that darts into the plasma
to measure right at the edge
where it's coolest.
It would actually be probably
a few million degrees,
but it darts in VERY quickly.
THEY LAUGH
Brilliant! What about
the middle, where...?
In the middle where it's
a hundred million, we have to
use laser-based techniques
to measure the temperature.
We shine a laser in and look
at the light that comes back.
And that gives you a really
accurate figure
without actually having to
touch the plasma.
Yes, the non-invasive technique.
Wow. Respect!
'I think, at last, I've got a sense
of what lies behind
'that simple measurement
of one degree on my thermometer.
'Going back to the woman
at the dinner party
who got me started on all this,
'I certainly feel I could have a
decent stab at explaining it to her.
'But her questions weren't
simply about that scientific idea -
'they were about what a temperature
rise of one degree means on average
'and that's where
things get a bit messy.
'I was back in Cambridge to meet
someone I hoped could help me.'
So I was having this conversation
and it became apparent
that she didn't really know
what an average was
so that when you might say, "The
average had increased by a degree,"
to her, that didn't really
sound very much
because every day the temperature
varies by much, much more than that,
and I slowly realised
I didn't really know
what an average was either -
sufficient to be
able to explain it -
and I thought you'd be
the right man to talk to.
OK, let's move away from temperature
and think about
another thing we can measure
like people's height.
So we talk about...
This is a scale of people's heights
and if we draw a curve like this...
where this shows sort of how many
people there are of each height.
So this is people of average height -
there's lots of them around -
and you've got short people down
here - there's a few of them -
and you've got really tall people
here and you've got a few of those.
So let's mark in
a really tall person.
So at the moment you've got that many
really tall people. Yeah.
So that may be 1 in 1,000,
1 in 10,000, something like that.
Six foot six. Something like that.
Let's say though that everyone grew
an inch, everyone got an inch taller.
Now what would happen is that
this distribution would shift...
..a little bit to the right. Yeah.
Round about the middle,
you wouldn't notice much at all.
If everyone in the street
was an inch taller,
I don't think you'd notice,
but if you're only looking at
really tall people,
now...
you've got a much bigger area.
The proportion of people who are
really tall has really gone up a lot.
If we put that into temperature,
that means that the days that are
really stinking hot in the past -
and they happen very rarely -
you only have to move
the mean temperature -
the average temperature - up a bit
and the number of those days
will really go up a lot.
In other words, if we're
talking about temperature,
say a rise of only a degree or so
in average temperature
will produce many more
very, very hot days? Yeah.
If we define a hot day
as something really uncomfortable,
if not dangerous - so very rare
at the moment -
those will become a lot less rare.
'As I've gone deeper into the
underlying science of temperature,
'one thing that's really stayed
with me is the value of measurement.
'Whether it's a million degrees...'
Oh, wow!
We're close to three kelvin.
'..a fraction
above absolute zero...'
That is mind-blowing, isn't it?
'..or taking readings
on my rooftop...
'..I've realised
that measuring temperature
'isn't simply a question
of fundamental physics.
'It matters to all of us.
'The Earth's average temperature
'has already increased by 0.75 of
a degree in the past 150 years
'and it's set to rise even further.
'That's why, for me, perhaps some of
the most interesting measurements
are taking place right here -
'in London W1.'
'Lift going up. Doors closing.
'The lift is now travelling
at 1,400 feet per minute.'
My ears have gone.
'Doors opening.'
'Dr Janet Barlow is one of
a new breed of meteorologists.'
Wow!
Fantastic, isn't it?
'She's managed to place her weather
station somewhere that's been closed
to the public for almost 30 years -
'on the top of the BT Tower,
191 metres above London.'
We've got the City
over to your right.
Over there. Oh, yeah, of course.
Brilliant!
You know, I'm really surprised
to know that
finding out what's going on
in terms of temperature in cities
is a new area.
Well, I think we've had a lot of
heat-wave events recently
and with concerns for the future,
we may get more heat waves,
but in cities
they're particularly intense
and we know from 2003,
many thousands of people died
in cities across Europe
because it was so hot,
so this is a real concern
for the future,
especially as cities like London
are going to expand
so those urban temperature effects
are only going to get worse.
I heard you had to
sneak up here to start with.
JANET LAUGHS
You think about things
in a very abstract way
and we had been thinking
for so long, "Wouldn't it be nice
"to get a temperature measurement, a
wind-speed measurement above London?"
And we just happened to be
walking out of a meeting
and there was the BT Tower
right in front of us.
So I thought, "Well,
you don't get if you don't ask,"
so I came and talked to
the security guards
and we came and made some
measurements within a few weeks.
'I really admire
scientists like Janet.
'She's investigating something
that ought to concern everyone
'because as cities like London
continue to grow,
'they're going to
keep getting hotter and hotter
'and that's without
even thinking about
'what climate change
will do to temperatures.'
So, Janet, this is like
a new frontier in temperature
measurement, isn't it?
You're right at the vanguard, doing
something no-one's done before.
Yeah, I mean, the BT Tower is
a really unique building in London.
It's so exposed to the atmosphere
compared to any other structure
that we have a really clear
idea of what's going on.
And from the initial results, having
a temperature measurement up here
compared to what we've got on the
ground, is giving us huge insight
into the way heat is carried
from the urban surface
up to the air above,
particularly at night-time when those
hot temperatures are occurring.
So going to show me your weather
station then? Oh, yes, of course.
BEN LAUGHS
How are you with heights, Janet?
I'm fine now, no problem.
UNCERTAINLY: Yeah.
Yeah, me too. Me too.
I'm great with heights, really good.
BEN MOUTHS
Whoa!
Wow!
Hang on,
where's your weather station?
It's up there.
Great, great...
Yeah, let's go up there -
that's going to be great(!)
That really is...
'I often complain about
health and safety,
'but for once I'm quite glad of it.
'To my relief,
they won't allow me up there.
'The weather station's data
is collected electronically,
'but for me to be able to
come up here and see this
'sums up everything about what makes
the science of temperature
'so fascinating
and so fundamental.'
So what does one degree,
what does that mean to you?
I think in the context of cities,
I'm looking at the difference between
the rural area and the city,
so, for example, how much bigger
does London have to get
to raise its temperature
by one degree?
That's a serious question
policy-makers are putting to us
and we have to do the calculations
and have the understanding
in order to answer it.
So after all this,
what is one degree?
To me, it represents
something so important
and that's measurement,
and that's why the woman
at the dinner party was so wrong
because we CAN know this stuff.
There's no arguing with measurement.
These things are fundamental.
And they reach right down
into the very roots of reality
and tell us unexpected, glorious,
confusing, odd, amazing,
sometimes unwelcome things.
Also one degree has
a personal meaning for me
because...I only got one degree.
Arguably, I should have
got another one as well,
but I didn't finish it
and I've always had a nagging
sense of guilt about that
and I feel that, just maybe,
on this journey,
I've paid...a small fraction
of that guilt off.
Not very much,
maybe just one degree.
PHONE RINGS
Coming!
Hello?
Hi, yeah, James, hello.
Yes, yes,
of course I've seen Avatar.
Yeah, I'd absolutely love to,
but I've got this weather station
on my roof, yes.
I have to take measurements
every morning,
so I'm afraid it's a no-show.
PHONE RINGS
Hello?
Where am I? James, I told you,
I can't make it. I can't come.
No, no, no,
I've got this weather station.
Yeah, remember,
regular measurements? Yeah.
Tell you what, try Rob Brydon.