JAUNTY MUSIC PLAYS
This is the story of an artefact.
No-one knows quite how many artefacts have been created
in the history of mankind,
but needless to say that there have been a great many of them.
From little Tommy Price's favourite catapult,
and Mrs Mirandes' decisively demonstrative damask doily...
..to young Pepina Peshlakai's perfect pre-teen pin-up.
Each is an ideal version and definitive example
of something truly important to its creator.
An object against which all others can be measured.
However, there are only a handful of artefacts that have been used
as references by everyone,
standards so essential that their very existence
underpins the functioning of our world.
Some were used to define lengths or volume or time.
Most have come and gone.
But the one that defines what things weigh - their mass - still remains.
Secured in an underground vault,
locked by three separate keys,
hidden from view -
an unchanging constant in an ever-changing world...
..until now.
History is about to be made.
Representatives of over 100 nations,
from Indonesia to Egypt,
are here to solve a crisis.
They put in millions of hours of effort
accomplishing engineering feats more complex than the moon landing.
These humble men and women aren't business leaders or politicians,
but their actions here will fundamentally change every aspect
of our lives, from economics to medicine.
Today, they will literally redefine the world as we know it.
We're trying to get rid of a kilogram.
But to understand what the kilogram actually is
and why they're so keen to get rid of it,
we should start this story at the beginning.
LAUGHTER
From the moment of our conception,
through every aspect of our lives,
from the inconsequential,
to the life-determining,
the high points...
..and the low,
right up to the very end...
BEEP
..everything about our existence is weighed and measured.
We're a species obsessed with quantifying things,
because objective measurements ensure everyone is dealt
a fair hand in life.
But that's a lot easier said than done.
Luckily for us,
there are hundreds of people
in different countries
spread out across the globe
working out the best ways to weigh and measure everything.
They are normal people with hopes, dreams, hobbies and desires,
just like you and me,
but with one minor difference.
These men and women are the tellers of time,
the masters of mass,
the safeguarders of standards.
They are metrologists.
Metrology is really very, very important
for industry and the society.
If there were no metrologists, we would have no measurement system.
And we do crazy stuff.
We measure glossiness of cats.
CAT MEOWS
We measure the acoustical crunches of biscuits.
We measure the fastest speed...
WHOOSHING AND TICKING
CLICK
..and we measure the smallest distance...
..and we measure the largest volume.
Metrology is the science or the art of measurement.
It means measuring things as in normal life,
but pushing this measurement to the limits of technology.
For centuries, metrologists have been working away
around the clock to ensure that there are, in fact,
accurate clocks to work around.
And consistent rules to measure with.
And equitable masses to weigh.
I think our motto should be,
"We worry about it so you don't have to."
But there is a problem that metrologists are worried about.
The weight of everything on the planet has been changing.
The change is so small few would even notice -
less than the weight of a grain of sand -
but they have.
No-one really knows why it was happening.
So that means no-one can stop it, really.
That's alarming.
It doesn't sound important but with pharmaceuticals,
that could be the difference between helping someone
or hurting them.
So, now it's up to the world's finest pathologists
to shoulder the heavy burden.
Together, they need to redefine the weight of the world,
fix it for all time.
But time...
..is not on their side.
The clock is ticking.
In just over a year, hundreds of delegates from around the world
will travel to the General Conference On Weights and Measures
in Versailles, expecting a solution to this weighty problem.
It's not enough to work day and night.
It's a scramble, it will be tight for us hitting the deadline.
To succeed, they need to complete one of the most difficult
experiments in the world,
ranked second only to the search for the infamous God particle.
I think it's fair to say that the number of people that are involved,
it's ridiculously hard and it's really great work
over many, many years.
But to solve this problem,
they'll need to shift the foundation of our entire measurement system.
To understand why requires a trip back to Paris.
More specifically, to an intergovernmental organisation
known as BIPM,
or the International Bureau of Weights and Measures.
BIPM, we are one of the oldest technical international
organisations in the world.
We're here in France, but we're not French.
It's led by director Martin Milton,
assisted by a team of staff,
including Dr Estefania de Mirandes
and Dr Richard Davis.
The BIPM uses its impartial status to act as an international guardian
of metrology, ensuring measurements are consistent,
accurate and fair for all.
And they are the curators of a truly extraordinary achievement
of mankind.
A list - or, rather, a system of definitions.
Le Systeme International. Or the SI for short.
It's a simple list, distilling all the essential properties
of our world into just seven definitions of base standard units.
It's because we share this system of units that it gets its power.
It means we can compare things in all the countries on Earth
easily, transparently.
The metre,
the second,
the mole.
These are the essential standards to which all our rulers,
clocks, thermometers and scales can be calibrated.
That provides the basis for all the types of measurement
that one needs for science and society and for quality of life.
I love the SI. I really love it.
And the reason I love it is
because it has humanity stamped all over it.
Do you know how many languages are spoken on our planet?
Do we have a feeling of that?
Huh? 300. 300?
No, 3,000.
3,000 different languages.
And it is very complicated for one group of people
to communicate with another group of people.
And so, to have a universal language in measurement,
that's a...that's a global story
and that's very, very beautiful.
But there is a problem with the SI.
One hidden in plain sight.
The kilogram,
a fundamental unit of the SI, is simply defined as...
"The mass of a kilogram is equal to
"the mass of the international prototype of the kilogram."
Mass is still tied to a single...
..a single artefact in the world...
..to a hunk of metal in Paris.
The International Prototype of the Kilogram,
or IPIK,
Le Grand K,
The Last Artefact.
The hunk of metal has many names,
yet it is utterly unique and absolutely irreplaceable.
It's an object that literally defines the weight of everything
else in the world.
Few ever get the chance to see something this priceless.
Except on a day like today.
CHATTERING
A small platinum iridium cylinder,
standing only 39 millimetres tall,
it's not a particularly impressive object to look at.
You have all these bell jars which surround it.
So you see this little, little thing just in a safe.
From one side you are excited,
and on the other side, it's just a piece of metal.
I mean, it's a strange thing.
How do you get excited about a small piece of metal in that way?
But it's what it stands for.
Anything that you weigh,
from an apple in a grocery store to drugs at a pharmacy,
eventually goes back to this prototype in Paris,
and it's an elaborate system
of traceability that we have to that
that enables us to get accurate weights for everything that we use
and buy and sell in the world.
Held in vaults across the world
are hundreds of copies of the kilogram.
None are exactly identical,
but all are calibrated precisely against the original.
So, for example, if you stand on a scale,
it will give you a weight
and you need to know if that weight is the right weight.
So, that scale has been calibrated against another scale,
which in turn has been calibrated against another scale,
and it runs all the way back.
And the top scales will be calibrated against the kilogram.
And that kilogram, in turn, is calibrated and measured
against the IPK kept in BIPM...
..which is THE kilogram,
which is the standard that all standards are compared to.
And this is the source of our weight-related problems.
This is what the kilogram - THE kilogram,
the International Prototype of the Kilogram - looks like.
Now, I'm handling it with my hands.
By definition, the mass of the International Prototype Kilogram
is the definition of the kilogram.
That means if you put a fingerprint on it, it's still a kilogram
and everything else in the universe has less mass.
That's a...
That's a ridiculous situation to be in.
That's not the only issue.
It's a man-made object - so, an artefact.
Everything that humans make, as a standard, decays.
Everything, as soon as it's made, it's beginning to decay
and change and evolve.
Everything is decaying.
Since it was forged, the IPK and its replicas have deviated
from one another by about 50 micrograms,
or the mass of a single eyelash,
shifting the world's weight with them.
We do not know whether the prototype, the artefact,
is losing its weight or it's accumulating its weight.
There's a fundamental problem with having an artefact that defines
the standard against which everything else
in the world is compared.
You want it to be isolated and kept separate,
but as the source of all the weighings in the world,
you want it to be used practically.
In order to solve the problem of the world's shifting weight,
there is only one solution.
So, we're dumping the lump. We're changing the system.
But that's not as easy as it sounds.
The kilogram is a fundamental, interlinked part of the SI units,
which means to redefine it,
you have to redefine the SI.
You have to change the way the world measures almost everything.
I always feel like if humanity is going to change something...
..go big.
To understand how we got into this situation in the first place,
and how we can fix it,
we should really start this story at the beginning.
LAUGHTER
No, the beginning of civilisation.
Measuring is a really simple idea,
and humans have been doing it since time immemorial.
If we go back to antiquity, thousands of years ago,
people measured things with stones and grains to make standards.
These consistent measuring references revolutionised fair trade
and, naturally, people gravitated toward standards
everyone can access, that were also close at hand,
like a hand or an eye.
Or arm.
But these seemingly democratic standards
have their own potential for short-changing.
If you measure a horse, you can measure in hands.
If you measure a horse and I measure a horse,
we're going to get a different size horse.
HORSE NEIGHS
So, many ancient rulers created empire-wide,
stable standards of measures.
So, for example, in ancient Egypt,
the cubit was the length of measure,
and that was the distance between the elbow and the tip,
or sometimes between the elbow and the tip of the finger,
plus a hand.
But those guys realised this wasn't going to let them build
the pyramids to the kind of accuracy that they needed to do,
so they made a standard.
Standardised artefact measures, like cubits,
allowed those in power to better build, govern and tax their empires.
Where you can compare something measured in one place with something
measured at another time, in another place,
and then measurement becomes really, really powerful.
But over centuries, these measurement standards multiplied
and massively muddled metrology
through the creation of more and more units.
Pounds, ounces... Pile, Charlemagne...
A yard...
Avoirdupois. Shaku.
Pint. Ls.
Miles. Feet.
Cun. A shekel. The inch.
By the 18th century, the list was so long
that some traders were dealing with 800 different units of measurement
and a quarter of a million definitions for them,
many of which weren't comparable.
And these inequities stirred up some serious discontent among the masses.
We know of the role that tea and taxes played
in the American Revolution,
but it could also be said that baguettes and bakers
played a role in the French Revolution just a few years later.
One of the very worst things that the revolutionaries
were concerned about in revolutionary France,
they were concerned about a lack of fairness with measurements.
Bread was the main component of the French working class diet.
The average 18th century worker spent half
their hard-earned dough on it.
It was so important, the king controlled all aspects
of bread production, including the price of loaves.
With France in the middle of a historic famine,
and different standard units of measure in each village,
weights could be fiddled,
so people were often paying the same for less
and the poor had no way to prove this was happening.
The peasants were hangry...
..and revolting.
France was in turmoil. It began with the execution of the king
and ended with the accession of Napoleon.
Obviously, the causes of the revolution were far more complicated
than the price of bread,
but it's fair to say it rather brought things to a head.
CHEERING AND APPLAUSE
When the revolutionaries took over,
it was recognised that one of their priorities would be to put in place
a measurement system that was going to be fair.
On April 7th, 1795,
true to their word...
A tous les temps, a tous les peuples.
"At all times, to all peoples."
The metric system was formally enshrined in French law.
This idea of
a Democratic approach to measurement,
this wasn't tied to the length of the king's foot
or something like that.
Instead, they turned back to constants found in nature,
but in a much more scientific and global way.
They were going to use the Earth itself.
Anybody could access the circumference of the Earth
and nobody could change the circumference of the Earth.
For example, a metre would be a fraction
of the planet's circumference.
But at the time, this proved too difficult
to measure precisely and consistently.
So they decided to create physical points of reference
for these new units - they made artefacts.
The original artefacts of the Metric Revolution
are now locked away in the Archives Nationales.
SPEAKING FRENCH
One of the first decisions of the National Assembly
was to create first the metre
and then the kilogram.
They defined a new unit of mass -
that was the mass of a litre of water -
and they called that the kilogram.
And this is the first prototype of what we call
le Kilogramme des Archives.
It was made at the end of the 18th century,
fabricated in platinum.
Under the French Revolution,
citizens could be involved in the decision-making process of the unit.
It's a kind of democracy.
Among the things that people were thinking about was...
..liberte, egalite, fraternite.
And part of this was that the system of measurement
should be something that should be accessible to everybody.
And that has been the mass system that we've maintained for years.
And it has worked.
It has served us well.
So, if it's not broken, why fix it?
Well, apart from the possibilities of damage to
or theft of an irreplaceable artefact,
metrologists are thinking about the future.
Redefinition allows us many things - two that come to mind.
One is we freeze any potential drift in the mass of this artefact.
Then it allows us to go from the quantum level
to the cosmic level without changing scales or units.
PHONE RINGS
Most science and a lot of technology is developed when we solve
a measurement challenge. MOBILE RINGS
Having better access to better definitions
and better measurement techniques actually propels the rest of society
and its scientific progress forward.
SMARTPHONE CAMERA SHUTTERS
And that brings us to the next step, which is to replace the present
definition of the kilogram with something that's not an object.
Something that doesn't change with time,
that doesn't get destroyed.
Something that you can reproduce everywhere, anywhere in the world.
We have faced this kind of situation repeatedly in metrology.
It used to be that a second was 1/24 x 60 x 60 of a day.
The trouble is that by the early 20th century,
it was clear that a day was not a constant thing.
And that realisation meant that we had to change
the definition of time.
And they did this by using what metrologists call
fundamental constants.
Fundamental constant doesn't change.
It's universally constant.
Today, the definition of time is based on atomic standards,
it's based on the unchanging frequencies of atoms.
And, like the second, fundamental constants have been used
to redefine other units of the SI.
Originally for the metre, it used to be a metre stick.
Now it's based on the speed of light in a vacuum...
Which sounds like it isn't a profound change,
but it actually is an incredibly profound change.
This moves the reference for objective reality away
from a man-made artefact and onto an unchanging constant
of the universe.
In the case of the kilogram, we're moving from an artefact
to basically an equation.
But, unlike the speed of light,
there's no obvious fundamental constant to redefine mass.
Cue two obscure but promising contenders -
one from chemistry,
the other from physics.
The teams representing each
are tackling the same kilogram-sized problem,
but a bit of friendly competition never hurts.
It's very challenging and then it's competitive, too.
There is national pride at stake.
Everyone wants to be the lab that changes the face of the kilogram.
One group set out to define the kilogram
using the Avogadro constant.
Of course there is competition.
Of course that is the power who brings us further.
The other, using the Planck constant.
One of the things that makes metrology unique
is we rely on other people repeating our measurements.
Rivalry in metrology is extremely useful.
People will go out of their way
to think of new ways of doing things.
And some of them will survive,
some of them won't.
Both routes would push the team to the limits of what's possible.
The first candidate is a fundamental constant from chemistry,
the Avogadro constant.
Named after the early 19th century Italian scientist Amedeo Avogadro,
the Avogadro constant is currently defined by the SI
as the number of atoms in one mole.
No, not that kind of mole!
The "mole" is a unit that describes the amount of substance
that's equal to the number of atoms in 12g of carbon-12.
This is currently calculated to be...
602 sextillion 214 quintillion...
..85 quadrillion 774 trillion atoms.
To put that in perspective, that's 80,000 times more atoms
than there are grains of sand in all the beaches,
deserts and sandpits in the entire world.
To further complicate things,
those 12g are still defined by the IPK.
So why, then, posited scientists, can't we do the reverse -
use Avogadro's constant to define the kilogram?
One of the teams tackling this is the...
..in Germany.
The PTB is a very accurate, organised little machine.
Not that little.
It's home to team members
including PhD student Edyta Beyer,
physicist and fossil hunter Ingo Busch,
and physicist, engineer and precision marksman Arnold Nicolaus.
They're working with the National Metrology Institute of Japan
to build cutting-edge technology to crack this Avogadro endeavour.
PIANO PLAYS
Here, team members, including prime senior researcher, and pianist,
Kenichi Fujii,
surface and nano-analysis group physicist, and flower arranger,
Lulu Zhang,
mass standards group leader, and weightlifter,
Naoki Kuramoto,
are led by director general, and avid motorcyclist,
Takashi Usuda. REVS ENGINE
When I'm hearing a great symphony,
it encourages me to invent something new.
PIANO PLAYS
FADES
Both teams are aiming to redefine the kilogram as an equation
by measuring the value of Avogadro's constant more precisely
and more accurately than ever before.
And they custom-make the perfect tools for the job.
I'm working with the roundest object on the Earth,
which is made from the purest silicon on the Earth.
And machining them is no walk in the park.
Mechanical engineer Rudolf Mees
has spent years perfecting the process.
The first steps, we remove several grams per hour,
but in the end, the removal rate is just one nanometre per minute
and takes three months to produce a sphere.
The result is an almost perfect sphere of almost perfect purity
and a price tag of several millions of dollars per sphere.
CASH REGISTER DINGS
Luckily for the Avogadro team, these spheres aren't irreplaceable
artefacts like the IPK.
Rather, they're just astoundingly accurate, if expensive, tools.
The silicon sphere is much more than just a mass standard,
it's a counting machine for atoms.
New spheres can be made.
But their perfection is priceless.
It allows them to be measured to previously unfathomable precision
and determine the exact number of atoms
inside each one.
But there are so many atoms inside that if you could count them
at a speed of ten million atoms per second,
it would take you 68 billion years.
Or about five times longer than the universe has existed.
So they use their sphere's remarkable shape and structure
to calculate Avogadro's constant instead.
Imagine we have a truck full of oranges.
So we measure the truck, that's the volume of the sphere.
We measure the volume of an orange,
that's the volume of the atom.
And together with the information about the inside organisation
of the oranges, we know exactly how many oranges
are inside and we can determine our Avogadro constant.
With their perfect spheres and meticulous measurement,
the Avogadro project aren't pulling their punches.
But there's another heavyweight contender competing
in the kilogram redefinition ring...
..the Planck constant.
Named after the German physicist who discovered it,
Max Karl Ernst Ludwig Planck,
it's a fundamental constant that even top metrologists
have trouble summing up.
If you go... Well, let's see how I can do this.
How would I...? I've got to think about this a bit more
cos that's a hard, hard question to explain
what Planck's constant is.
Oh, God, jeez. Erm...
Did we want to try and describe what Planck's constant is?
Erm, no.
The actual constant may be hard to explain,
but the concept is easy enough.
In the late-1800, physics was facing a crisis.
Physicists were trying to model atomic vibrations,
but they kept getting it wrong.
They'd assumed that atomic vibrations were continuous.
That is, they could vibrate at any frequency.
Planck came up with a kind of a crazy idea.
He said it's not a continuous process.
It's always in little packets of energy,
that today we call photons.
Think of it like your morning coffee.
When you order your Americano,
you can add sugar in two different ways -
as a continuous stream
or as cubes.
Planck postulated that you could only change energy
in minimal increments,
like sugar cubes.
And the field of quantum mechanics was born.
It was a surprise to everyone that energy was quantized,
and it changed our understanding of physics entirely.
And because Planck's constant relates to energy,
you can link it to an object's mass via Einstein's relativity equation,
energy is equal to mass times the speed of light squared,
using Planck's constant to redefine the kilogram.
But first, metrologists have to measure it.
Doing the heavy lifting for the Planck constant are labs like
the National Research Council,
in Canada.
CHATTERING
We spent a lot of hours, a lot of long, long hours.
Physics runs on coffee for the most part.
Team members including research offices in electrical measurements
Carlos Sanchez and Barry Wood,
and dedicated dad and team leader in mass metrology Richard Green,
are led by Canada's chief metrologist Alan Steele.
Intense, dedicated.
You know, no fear of taking things apart
and putting them back together over and over and over again
until you get it right.
The NRC are joined by yet another set of Planck pioneers...
O SAY, CAN YOU SEE PLAYS
..from the National Institute of Standards and Technology,
in the United States of America.
PLAYS BLUES GUITAR
Team members include chief of the Quantum Measurements Division,
and string-strummer, Jon Pratt.
It's certainly a common stereotype,
but I feel like it's a little bit of truth -
the US tends to be a little bit more freewheeling
on these types of things.
"Ha, that's a great new idea! Let's go do that!"
Leader of the Mass and Force Group, and coffee aficionado,
Zeina Kubarych,
Mass and Force Group physicist, and technical tinkerer,
Patrick Abbott,
and Fundamental Electrical Measurements Group physicist,
and should-be prizewinning pretzel maker, Stephan Schlamminger.
I think we have a very strong team.
I think there's almost no technical problem that we can't solve.
To derive the most precise and accurate possible value
of Planck's constant, both teams are measuring a readily available
supply of calibrated kilograms
in an electromagnetic device called a watt balance.
The watt balance is simply a clever device that can weigh a mass
using only electrical measurements.
The watt balance's basic principle is
you're comparing a gravitational force to electromagnetic force.
Think of it like an electromagnet in a scrapyard.
Larger cars have a greater gravitational force pulling on them,
making them heavier,
so more electrical current is required to overcome gravity
and lift a heavier car.
CHILD LAUGHS
Except, instead of pulling an object upwards,
the watt balance electromagnet pushes it up
against the force of gravity until the electrical force equals
the mass of the now balanced object
without the need to compare it to anything
on the other side of the scale.
This gives the watt balance the ability to link electrical energy
and its base unit, Planck's constant, to the mass of an object.
But devising a device to measure the quantity of this force exactly
required the genius of Dr Bryan Kibble,
who cracked the engineering of the world's first watt balance...
..at the National Physical Laboratory
in the United Kingdom.
This laboratory was where the watt balance was born.
Bryan Kibble and I built the first one here.
Today, the balance is also called the Kibble balance,
in honour of its inventor.
His legacy lives on through the work of the lab's many contributors,
including electrical measurement specialist Ian Robinson
and research scientist Perdi Williams.
I don't think you could get a more British place
than this crazy British lab.
We have tea parties in the office and there's a grand piano.
Cheers.
I described the basement lab as Ian's brain
has just thrown up in a lab.
Some of the most ground-breaking science is done in a messy,
unorganised shed in the basement of a massive stately home.
Whilst the NPL are no longer in the business of weighing kilos,
they are leading the world in building affordable
miniature Kibble balances for the masses.
We're now in the lucky position of being able
to build a generation of balance
that should take the balance out and make it egalitarian.
Everybody in the world should be able to access
this technology and contribute to the world mass scale.
And they're lending their expertise in watt balance building
to a devilishly difficult task for good reason.
Measuring the Planck constant to the level that we need
is extremely difficult.
Working with the watt balance is, I would say,
an emotional roller-coaster.
Bring it down and have a look.
And building this thing was exhausting
and kind of, "Oh, my God, is it going to work?" You know?
Can you see it? Stop it there.
The watt balance is a really, really hard experiment.
These instruments tend to have a certain character to them
that only the people who built them can really make them work the way
that they're supposed to work.
We need to consider about 100 different effects that affect
the measurement.
From noise, temperature, magnetic fields,
we need to measure all those things and to a level
that we haven't been able to measure before.
This is a big change we're proposing.
We'd like to get it right.
After years of painstaking trial and error,
a decision has to be made about which fundamental constant
would redefine the kilogram.
In 2011, the metrological community decrees Planck,
and its ability to link all electrical units in the SI,
as their constant of choice.
But there's a twist
which means that the work of the Avogadro teams
can still contribute to the redefinition effort.
The Avogadro constant and Planck's constant are very closely related
to each other.
If you have one of these two constants,
you will get the second constant for free.
And that's the way Planck's constant occurs in the silicon sphere.
That's it.
The challenge now becomes that the Planck values
from both experiments must match.
So if both projects result in the same numbers,
then I think there is no doubt to redefine the kilogram.
If they don't, then something has gone very wrong.
Today is one of the most important meetings
of the Consultative Committee for Mass.
Today is the deadline for the teams to get their results in.
Everybody is coming up with their answers at the very last minute,
Canada's was just accepted about a week and a half ago.
The German Avogadro number came about three or four days ago.
The NMIJ one came out about two days ago.
Just yesterday, I think it was, from the United States.
Today, they decide if the data is good enough to be put to the vote.
The CCM put up some conditions
which should be fulfilled in order to go for redefinition.
We want to all have agreement on what the value
for Planck's constant is, and a new value has come online
which is controversially maybe possibly a little bit out.
Some countries think that the criteria have been met and others
think they have not been met.
And this is now an intense discussion on how we should proceed.
If they cannot reach an agreement,
the whole redefinition could be called off.
For us, it would mean four more years of digging for uncertainties.
And I don't think we can...
I don't want to do that. I want to move on to other science.
As the debate becomes more heated,
it continues behind closed doors.
One year ago, I would have said
everything's set for the redefinition.
Now, in the recent times, I'm not certain if the current status
of knowledge will be considered to be enough
by the general conference.
But in the always exciting world of metrology,
nothing is ever straightforward.
The teams are being given just two months to publish values
in closer alignment for Planck's constant
or risk putting next year's redefinition vote in jeopardy.
Right now, we should be writing.
And we're still not writing our article,
instead we are still doing measurements.
So I think it will be a close call.
I think we have a whole bunch of all-nighters to get it done.
Once the papers are in,
the Avogadro and Kibble balance teams
will average their numbers to obtain the lowest possible uncertainty
for the final fixed value of Planck's constant.
Uncertainty is always sort of this measurement of how confident
you are in that number.
The worst thing a metrologist can do is have a number that turns out
to be outside their uncertainties.
And that's...that's our idea of hell, I think.
We still have some problems to solve.
And I think the pressure is too big for the redefinition
and for the redesigning of the SI.
I'm sympathetic to the conservatives,
but I'm also a US guy and I'm just, like, let's change.
The final agreed numbers for Planck's constant roll in,
fixing its value in the kilogram equation.
There's nothing more the teams can do but wait.
It's now up to the metrological community of the world to vote
on whether their consensus value for Planck is good enough
to redefine the kilogram.
TENSE MUSIC PLAYS
We're going to Versailles to go and watch the vote!
We'd better redefine the kilogram.
We've done too much work not to do it.
Today's vote will determine whether the kilogram will become
an equation using Planck's constant,
or if it will remain an artefact.
The fact we've got multiple experiments, multiple labs,
means that we're pretty sure we've got the right answer.
Well, not "pretty sure" - we've GOT the right answer.
Now we're really getting close to a win-win-win situation,
so it's...nobody loses.
So why would anybody want to delay?
It's way past time to re-define.
You don't want science to ever be limited by one particular artefact
or one particular laboratory or one particular experiment.
And now we're ready.
I think it's...it's time.
Ladies and gentlemen, you have heard that the proposal for the revision
of the SI is that it should be based on constants,
on fundamental constants.
Mr President, I think we're ready to propose the vote.
Thank you. Each country will be called
and you will say yes or no.
Canada.
SPEAKS FRENCH
Oui. Oui?
Well, come here!
APPLAUSE
Kenya. Yes.
And India. Yes.
Japan. Yes.
CHUCKLES
United States of America. Yes.
Korea. Yes.
Iran. Yes.
China. Yes.
Yes. Yes.
Yes!
CHUCKLING
The definition of the kilogram is free from the artefact.
We've redefined the kilogram.
The vote was unanimous.
Thank you so much.
APPLAUSE
To witness a historic moment like that and be a part of it,
I know that this is something I will remember forever.
It was the ride of my life, you know? It was a lot of fun.
We measured Planck's constant, but what people really want to see...
Are the tattoos. ..are the tatts.
My tattoo in no way resembles my job role,
but I have Keeper Of The Kilogram tattooed on my back.
The idea of the French,
that it would be a system of units for all people for all times,
I think we're really a lot closer to that now.
You know, I'm just overwhelmed with the community that was built
and come to consensus and make progress...
..real progress...
..for mankind.
In a monumental metrological moment,
a Democratic equation anyone can access at any time
takes its place as the definition of the kilogram.
While metrologists get back to work,
the rest of the world continues unaware.
OK, so what's going to change when we change the kilogram?
How is that going to affect the average person?
When the kilogram is new-defined and when we do a good job,
no-one will notice it. But that's good.
When the person on the street will start seeing differences
is when new technologies start getting built into better science
or better products.
I think that might happen in individualised medicine
or cellular medicine or pharmaceuticals.
The better we get at measuring something,
the bigger the world of opportunity for scientific exploration becomes.
There's a new undiscovered land.
You know, we have wiped out all the maps and said,
"OK, something completely new."
Some people think metrology is dull.
They think it's some kind of accountancy.
That completely misses the point.
Metrology is looking closer and closer at things,
seeing their form more perfectly,
seeing them more clearly in themselves,
and just appreciating the full wonder
and beauty of the world we have around us.
WARM PIANO PLAYS
So, Le Grande K isn't really going away.
It's going to be in that vault, but it's still going to be with us
because its mass at the time of redefinition
is essentially built into the Planck's constant.
It's immortalized, if you will.
I feel quite weirdly protective over a lump of metal.
And, I mean, if they do want to get rid of it one way,
I'm happy to take it home and look after it.
PIANO PLAYS