Can I hold it? Only if you promise to be really, really careful. I promise I will be so incredibly careful. I will be incredibly careful with it. Okay. I promise. All right. So, it's slippery. Be careful. All right. Are you ready? I'm about to touch a 1 kilogram sphere of silicon-28 atoms. There are about 2.15 * 10^25 of them. It feels absolutely incredible. Wow. That is amazing. Besides its creators, I am one of only a handful of people ever to hold this sphere. The raw material used to make it was worth 1 million euros, but now that it has been so precisely sculpted... How much is that worth? It's priceless. This you are looking at now is the roundest object in the world. How can you say for sure that it's the roundest object? I mean, the Earth is pretty round, isn't it? If this was the Earth, then the highest mountain and the lowest valley would be about 14 meters apart. That is shocking. That is shockingly round. But why would you invest 1 million euros and thousands of man-hours perfecting a pure, polished silicon sphere? Well, the answer is grave. Or rather, grave, as it would have been pronounced in the original French. You see, the grave was the original name for the base unit of mass in the metric system, which became the Systeme International d'Unites, or SI units. In 1793, a commission, which included notable scientist and aristocrat Antoine Lavoisier, defined the base unit of mass as the weight of a cubic decimeter of water at the melting temperature of ice. Essentially, just a liter of ice water. The name grave came from the Latin gravitas, meaning weight, but it wasn't to last. It sounded too similar to the aristocratic title Graf, which is the equivalent of an Earl or a Count. And with the French Revolution in full swing, with a rallying cry of equality for all, you couldn't exactly have one unit nobler than the others. At this, Lavoisier lost his head, literally. Not because he helped devise one of the greatest systems of measurement of all time, but because he was collecting taxes as a nobleman. So, things really were grave. The new Republican government believed a grave would be too big for the things they wanted to measure anyway, and so they settled on a gramme, which was just a thousandth of a grave. But soon they realized that a gram was too small, and so they returned to the grave. But since they couldn't call it that, they invented the kilogramme, a thousand grams. And that is why, out of the seven base SI units, the kilogram is the only one to have a prefix in its name. In 1799, the kilogram definition was refined to be the mass of a liter of water at 4 degrees Celsius, the temperature at which it is densest. But water itself is obviously not the most sensible thing to use as a mass standard. So, a pure platinum cylinder was created to have the same mass as the water definition. And it was declared Kilogram of the Archives. Now, it's important to note at this point, the kilogram is no longer tied to the mass of a volume of water. The Kilogram of the Archives is, by definition, the kilogram. 90 years later, in 1889, the kilogram was upgraded to a platinum-iridium alloy cylinder. Now, it was much harder than the original but was otherwise basically identical. And to this day, it remains the definition of the kilogram. It is officially called the International Prototype Kilogram, though it's affectionately known as Le Grand K, or Big K. Oh, and it's about this big. It is the only thing in the entire universe with a mass of exactly 1 kilogram, because it is the kilogram. It is also the only SI unit that is still defined by a physical object. It sits under three bell jars next to six sister kilograms in a climate-controlled vault, locked by three independently controlled keys in the basement of the International Bureau of Weights and Measures on the outskirts of Paris. Now, if you were able to break into the vault and tamper with Big K, you would actually be changing the definition of the kilogram, a definition on which many of our measurements rely. And so you would throw the world into chaos. Well, no, not actually. But how would anyone ever know if the mass of Big K changed? Well, when it was first created, 40 identical replicas were also made. Well, they weren't quite identical. They had a mass which was slightly different to Big K, but those offsets were recorded. Now, these replicas were sent out to countries around the world to serve as their national standards. In 1948, the kilograms were reunited for a weigh-in. And this is when the problems started. Because even though all the cylinders were made of the same alloy and stored under virtually the same conditions, their masses had diverged over time. The mass of Big K wasn't even the same as the six sister cylinders stored with it. And to make matters worse, when they were brought together again 40 years later, their masses had further diverged, up to about 50 micrograms. That's about the weight of a fingerprint. But fingerprints were not the culprits, since the kilograms were carefully washed before their weigh-ins. So some physical process must have actually changed the mass of the cylinders. But how that exactly works remains a matter of speculation. One thing is for certain, the mass of a platinum-iridium cylinder is not stable over time. And this is a big problem. You can't have a unit which changes its value. And the fallout isn't limited to measurements of mass. Since of the seven base SI units, four of them depend on the mass of the kilogram. Not to mention all the derived units like Newtons, Joules, Volts, and Watts. At this point, those of you in countries that have not adopted the metric system, yes, I'm speaking to you, Liberia, Burma, and the US, you may be feeling rather smug that your base unit of mass, the avoirdupois pound, is no longer defined by a physical object. No, instead, it is defined as precisely 0.45359237 kilograms. Sucked in. So clearly, something needs to be done to eliminate the kilogram's dependence on a physical object. And this is where the silicon sphere comes in. But how exactly does that help? Here you have a physical object, and it's beautiful, but, you know, it's still a physical object. You're trying to get away from that. We're trying to get away from the physical object, but what we're doing with this particular object is counting how many atoms are in there. You can't actually count how many are in there, can you? You can't count how many are in there, but you can calculate how many are in there because this material is silicon. There's no voids or dislocations. So this is like a perfect crystal of silicon. That's right. Not only is it pure silicon, it contains only one isotope of silicon, silicon-28. And that explains why the original material was so expensive. And why a sphere? Well, a sphere is a pretty simple object. If you know the diameter of the sphere, you can characterize the entire dimension of the object. Well, that explains why the sphere has to be the roundest object ever created. But how do you actually make something that round? We actually start with an oversized sphere. So it was about 2 mm larger in diameter. And then we just grind it progressively finer and finer using an abrasive that's actually massaging atoms. You're down at that level of of trying to control the shape of an object down at the atomic level. But making the sphere is only half the battle. Then you need to accurately measure its diameter. The diameter is actually measured by a laser. So you're actually measuring, having the sphere in the center of a cavity and the laser is hitting both sides and you're actually measuring the gap. By knowing the diameter, you can determine its volume. And since the atom spacing of silicon is known to high precision, you can then calculate how many atoms make up the sphere. This allows you to redefine Avogadro's constant. At the moment, Avogadro's constant is defined based on the kilogram. It is equal to the number of atoms in 12 grams of carbon-12. But using this approach, the number of silicon atoms in the sphere would be used to fix Avogadro's constant, which would then define the kilogram. So even if the silicon spheres were lost or damaged, it would have no effect on the definition of the kilogram, because it would be defined not by a physical object, but by a concept. You would like to see the official definition of the kilogram say, a kilogram is the mass of 2.15 * 10^25 silicon-28 atoms. Yes. Which is not going to happen. There's a there's a high likelihood that it's going to happen. But there is another approach to redefining the kilogram, which involves fixing Planck's constant. And it's done using something called a watt balance. These two approaches are complementary. Each one provides a check on the other. And if they show good agreement and are able to bring their uncertainties down to about 20 micrograms, they may redefine the kilogram as early as 2014. And then the kilogram finally will be an unchanging unit, no longer defined by a physical object in the basement vault of some place in Paris. Now, if the kilogram was originally intended to be the mass of a liter of water at its densest temperature, then how well did we do? Well, if you look at a liter of water at nearly 4 degrees Celsius, it has a mass of 999.975 grams. So, I guess you could look at this two ways. On the one hand, you could say the kilogram is slightly heavier than it should be. But on the other hand, 214 years ago, scientists were able to create an artifact that was correct within the margin of error of a grain of rice. Now that is truly remarkable. Now, if you want to hear more about the watt balance, let me know in the comments and I will see what I can do. It does seem to be the front runner in terms of redefining the kilogram. So, we will have to wait and see what happens. One last thing, I should point out that it took an international collaboration of scientists to create the silicon sphere. But don't you think that the scientist who originally conceived of silicon as an element should receive some of the credit? Well, in 1787, that was none other than Antoine Lavoisier. So he's been involved in the definition of a kilogram from start to finish, or from cradle to grave.
A man asks a woman if he can hold an object, and she cautiously agrees.
"Can I hold it? Only if you promise to be really, really careful."
Setting: scientific laboratory — bright, even fluorescent lighting
People (2):
• standing, facing the man, wearing white short-sleeved collared shirt, dark brown, tied back hair — smiling
• standing, facing the woman, wearing bright blue polo shirt, dark brown, short hair — smiling broadly, looking at the woman
Text: "Ms. Katie Green", "PRECISION OPTICS, CSIRO"
The man leans down towards a shiny sphere on a stand, looking at it with excitement.
"I will be incredibly careful with it. Okay. I promise."
Setting: scientific laboratory — bright, even fluorescent lighting
People (2):
• leaning forward, wearing bright blue polo shirt, dark brown, short hair — smiling, wide-eyed, looking at the sphere
• standing, wearing white short-sleeved collared shirt, dark brown, tied back hair — smiling
The man puts on a white glove and prepares to touch the sphere, laughing with anticipation.
"All right. Are you ready?"
Setting: scientific laboratory — bright, fluorescent
People (1):
• leaning forward, wearing bright blue polo shirt, dark brown hair — laughing, eyes wide with excitement
The man, wearing a white glove, slowly lowers his hand and makes contact with the perfectly smooth, reflective sphere.
"I'm about to touch a 1 kilogram sphere of silicon-28 atoms. There are about 2.15 * 10^25 of them."
Setting: scientific laboratory — bright
People (1):
• leaning over the sphere, wearing bright blue polo shirt, dark brown hair — intense concentration, mouth slightly open
The man lifts the heavy, reflective sphere off its stand, holding it in his gloved hand and looking at it in amazement.
"It feels absolutely incredible. Wow. That is amazing."
Setting: scientific laboratory — bright, even
People (1):
• sitting/leaning, holding the sphere, wearing bright blue polo shirt, dark brown hair — smiling broadly, eyes wide with awe
A person wearing gloves carefully handles a rough, cylindrical piece of dark, shiny silicon, taking it out of plastic packaging.
"The raw material used to make it was worth 1 million euros, but now that it has been so precisely sculpted..."
Setting: workshop or laboratory — bright, direct
People (1):
• standing at a table, wearing white lab coat over a blue shirt, not visible hair — not visible
Text: "CSIRO"
The man and woman stand in the lab, laughing, as he points at the sphere on its stand.
"How much is that worth? It's priceless."
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — laughing
• standing, wearing blue polo shirt, dark brown hair — smiling, looking at the woman
The man gestures with his hands as he questions the woman's claim about the sphere's roundness.
"How can you say for sure that it's the roundest object? I mean, the Earth is pretty round, isn't it?"
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — smiling, laughing
• standing, wearing blue polo shirt, dark brown hair — smiling, gesturing as he speaks
The man reacts with laughter and surprise to the woman's explanation of the sphere's roundness.
"If this was the Earth, then the highest mountain and the lowest valley would be about 14 meters apart."
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — smiling, looking at the man
• standing, reacting, wearing blue polo shirt, dark brown hair — laughing, mouth open in surprise
The man speaks directly to the camera, posing a question, with a blurry background of a cemetery.
"But why would you invest 1 million euros and thousands of man-hours perfecting a pure, polished silicon sphere?"
Setting: cemetery — overcast, diffuse daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — serious expression, mouth forming words
The camera shows a wide shot of a cemetery with many white tombstones under an overcast sky. The word 'Grave' appears in large, brown, serif font.
"Well, the answer is grave."
Setting: cemetery — overcast, flat daylight
Text: "Grave"
The man speaks to the camera in a cemetery, explaining the historical context of the word 'grave'.
"You see, the grave was the original name for the base unit of mass in the metric system, which became the Systeme International d'Unites, or SI units."
Setting: cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — serious, explaining
Text appears on a textured, parchment-like background, explaining the origin of SI units.
"which became the Systeme International d'Unites or SI units."
Setting: n/a — n/a
Text: "Système International d'unités", "SI unités"
An 18th-century style illustration of Antoine Lavoisier is shown, with his name appearing as text.
"notable scientist and aristocrat Antoine Lavoisier, defined the base unit of mass as the weight of a cubic decimeter of water at the melting temperature of ice."
Setting: illustrated study or lab — soft, directional
People (1):
• standing next to a table with scientific apparatus, wearing brown coat over a decorative waistcoat and dark green breeches, white, powdered wig style hair — stoic, looking to the side
Text: "Antoine Lavoisier"
A simple animation shows a cube being drawn, labeled with its dimensions and temperature, representing the definition of the original kilogram.
"as the weight of a cubic decimeter of water at the melting temperature of ice."
Setting: n/a — n/a
Text: "0.1 m", "0°C"
An animation shows a cube of ice water with the word 'Grave' which then changes to 'Gravitas (weight)'.
"The name grave came from the Latin gravitas, meaning weight, but it wasn't to last."
Setting: n/a — n/a
Text: "Grave", "Gravitas (weight)"
An 18th-century style illustration of an aristocrat is shown with the word 'Graf' and its meaning.
"It sounded too similar to the aristocratic title Graf, which is the equivalent of an Earl or a Count."
Setting: illustrated room — n/a
People (1):
• standing, wearing brown coat, white shirt and dark breeches, white powdered wig hair — stoic
Text: "Graf (Earl/Count)"
A famous painting of the French Revolution, 'Liberty Leading the People', is shown with the word 'Égalité' overlaid.
"And with the French Revolution in full swing, with a rallying cry of equality for all, you couldn't exactly have one unit nobler than the others."
Setting: Paris, during the French Revolution — dramatic, chiaroscuro
People (1):
• dynamic poses of fighting and dying, wearing 19th-century revolutionary attire, various hair — various expressions of struggle and determination
Text: "Égalité"
A black and white historical illustration depicts a beheading by guillotine during the French Revolution.
"At this, Lavoisier lost his head, literally."
Setting: place of execution — n/a
People (1):
• various poses related to the execution, wearing 18th-century attire, various hair — various
An animation shows a large blue cube representing a 'Grave' shrinking into a tiny blue cube, with the word 'gramme' appearing.
"and so they settled on a gramme, which was just a thousandth of a grave."
Setting: n/a — n/a
Text: "gramme"
An animation shows a large cube made of 1000 smaller cubes appearing, with the word 'kilogramme' below it.
"they invented the kilogramme, a thousand grams."
Setting: n/a — n/a
Text: "kilogramme"
A list of the seven base SI units is displayed on a parchment background, with 'kilogram' highlighted in red.
"the kilogram is the only one to have a prefix in its name."
Setting: n/a — n/a
Text: "mol", "Kelvin", "candela", "second", "Ampere", "metre", "kilogram"
The man stands in a cemetery by the ocean, holding a clear plastic container of water and explaining the refined definition of the kilogram.
"In 1799, the kilogram definition was refined to be the mass of a liter of water at 4 degrees Celsius, the temperature at which it is densest."
Setting: seaside cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — explaining, looking at the camera
Text: "1799", "4°C"
A photo of an old, dark metal cylindrical weight with a knob on top is shown on a parchment background, with a stamp-like graphic appearing.
"So, a pure platinum cylinder was created to have the same mass as the water definition. And it was declared Kilogram of the Archives."
Setting: n/a — n/a
Text: "KILOGRAM of the ARCHIVES"
A photo of the 'Kilogram of the Archives' is shown with French text overlaid.
"The Kilogram of the Archives is, by definition, the kilogram."
Setting: n/a — n/a
Text: "Ceci est un kilogramme"
The man stands in a cemetery with a palm tree, explaining the history of the kilogram.
"90 years later, in 1889, the kilogram was upgraded to a platinum-iridium alloy cylinder."
Setting: cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown, slightly windblown hair — speaking to camera
Text: "1889"
The man continues his explanation in the cemetery.
"And to this day, it remains the definition of the kilogram."
Setting: cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — serious, speaking with emphasis
Text appears on a parchment background, stating the official name of the kilogram prototype.
"It is officially called the International Prototype Kilogram, though it's affectionately known as Le Grand K, or Big K."
Setting: n/a — n/a
Text: "International Prototype Kilogram", "Le Grand K (Big K)"
The man stands in the cemetery, holding up a small, shiny, cylindrical metal weight to the camera.
"It is the only thing in the entire universe with a mass of exactly 1 kilogram, because it is the kilogram."
Setting: cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — smiling, speaking with conviction
An image shows the International Prototype Kilogram under multiple glass bell jars on a golden base.
"It sits under three bell jars next to six sister kilograms in a climate-controlled vault,"
Setting: vault (implied) — studio lighting, highlighting the object
A satellite view zooms in from Europe to a specific building complex in Paris.
"in the basement of the International Bureau of Weights and Measures on the outskirts of Paris."
Setting: Paris, France — daylight
The man stands in the cemetery holding the small weight, explaining the consequences of altering the prototype.
"you would actually be changing the definition of the kilogram, a definition on which many of our measurements rely."
Setting: cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — serious expression, explaining a concept
The man poses a rhetorical question to the camera.
"But how would anyone ever know if the mass of Big K changed?"
Setting: cemetery — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — questioning expression
An animation on a parchment-textured world map shows kilogram replicas being distributed from France to various countries.
"Now, these replicas were sent out to countries around the world to serve as their national standards."
Setting: world map — n/a
The man stands in a seaside cemetery, explaining a turning point in the history of the kilogram.
"In 1948, the kilograms were reunited for a weigh-in. And this is when the problems started."
Setting: seaside cemetery — overcast
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — serious, explaining
Text: "1948"
A simple graph is drawn on a parchment background, showing multiple lines diverging from a single point over time.
"their masses had diverged over time."
Setting: n/a — n/a
Text: "Change in Mass", "Year", "1948"
The graph on the parchment background extends, showing the lines diverging even more over time.
"their masses had further diverged, up to about 50 micrograms. That's about the weight of a fingerprint."
Setting: n/a — n/a
Text: "Change in Mass", "Year", "1990", "50µg"
The man stands in the seaside cemetery, explaining the mystery of the changing mass of the kilogram prototypes.
"So some physical process must have actually changed the mass of the cylinders. But how that exactly works remains a matter of speculation."
Setting: seaside cemetery — overcast
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — pensive, explaining a complex problem
The man stands in front of a background of the ocean and sky, making a definitive statement about the problem with the kilogram.
"One thing is for certain, the mass of a platinum-iridium cylinder is not stable over time. And this is a big problem."
Setting: seaside — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — serious, looking directly at the camera
A list of the seven base SI units is shown on a parchment background, with four of them plus the kilogram highlighted in red.
"Since of the seven base SI units, four of them depend on the mass of the kilogram."
Setting: n/a — n/a
Text: "mol", "candela", "Ampere", "kilogram"
A man's hand holds a small, historical-looking metal weight with a wooden handle.
"your base unit of mass, the avoirdupois pound, is no longer defined by a physical object."
Setting: indoors, possibly a museum or collection — soft, indoor
People (1):
• examining the object, wearing light blue shirt, dark brown hair — smiling
Text: "avoirdupois pound"
A long decimal number appears on a parchment background, showing the exact definition of a pound in kilograms.
"No, instead, it is defined as precisely 0.45359237 kilograms."
Setting: n/a — n/a
Text: "0.45359237"
The man smiles cheekily at the camera after revealing the pound's definition, then becomes serious again.
"Sucked in. So clearly, something needs to be done to eliminate the kilogram's dependence on a physical object."
Setting: seaside — overcast
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — smirking, then transitioning to a serious expression
A gloved hand carefully places the perfectly round, reflective silicon sphere into a container filled with white protective material.
"And this is where the silicon sphere comes in. But how exactly does that help?"
Setting: laboratory — bright, indoor
People (1):
• handling an object, not visible hair — not visible
The woman explains the scientific process, gesturing with her hands for emphasis.
"We're trying to get away from the physical object, but what we're doing with this particular object is counting how many atoms are in there."
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — serious, explaining
• standing, wearing blue polo shirt, dark brown hair — listening intently
The woman explains that the number of atoms is calculated, not directly counted, due to the material's purity.
"You can't count how many are in there, but you can calculate how many are in there because this material is silicon."
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — explaining
• standing, wearing blue polo shirt, dark brown hair — nodding, understanding
The man confirms his understanding that the sphere is a perfect crystal, and the woman agrees.
"So this is like a perfect crystal of silicon. That's right."
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — smiling, nodding
• standing, wearing blue polo shirt, dark brown hair — asking a question, looking at her
A man in a white lab coat grinds a grey, unfinished sphere in a bowl-like machine.
"And why a sphere?"
Setting: workshop — bright, functional
People (1):
• standing, working at a machine, wearing white lab coat, balding, gray hair — focused on his work
A graphic overlay appears on the sphere, showing a line representing the diameter labeled with 'd', while the woman explains.
"Well, a sphere is a pretty simple object. If you know the diameter of the sphere, you can characterize the entire dimension of the object."
Setting: laboratory — bright
Text: "d"
A person wearing gloves uses a brush to apply a grey paste to an unfinished sphere in a grinding bowl.
"We actually start with an oversized sphere. So it was about 2 mm larger in diameter. And then we just grind it progressively finer and finer using an abrasive"
Setting: workshop — bright, direct
People (1):
• working over a bowl, not visible hair — not visible
A man in a lab coat operates a complex polishing machine with two large bowls, working on a sphere.
"you're down at that level of of trying to control the shape of an object down at the atomic level."
Setting: laboratory — bright, fluorescent
People (1):
• standing, leaning over the machine, wearing white lab coat and dark pants, balding, gray hair — concentrating on his work
A close-up shot shows a laser interferometer measuring the diameter of the silicon sphere with extreme precision.
"The diameter is actually measured by a laser. So you're actually measuring, having the sphere in the center of a cavity and the laser is hitting both sides and you're actually measuring the gap."
Setting: metrology lab — focused, technical lighting
An animation on the sphere shows the formula for volume, then divides by the density of atoms to get the number of atoms.
"By knowing the diameter, you can determine its volume. And since the atom spacing of silicon is known to high precision, you can then calculate how many atoms make up the sphere."
Setting: laboratory — bright
Text: "V=πd³/6", "÷ density of atoms", "=# of atoms"
An animation on a parchment background shows that the kilogram currently defines Avogadro's constant.
"This allows you to redefine Avogadro's constant. At the moment, Avogadro's constant is defined based on the kilogram."
Setting: n/a — n/a
Text: "kg → NA"
An animation shows how the number of atoms in the sphere can be used to fix Avogadro's constant, which in turn defines the kilogram.
"the number of silicon atoms in the sphere would be used to fix Avogadro's constant, which would then define the kilogram."
Setting: n/a — n/a
Text: "kg ← NA"
The man and woman discuss the potential new definition of the kilogram, smiling.
"a kilogram is the mass of 2.15 * 10^25 silicon-28 atoms."
Setting: scientific laboratory — bright
People (2):
• standing, wearing white shirt, dark brown hair — smiling
• standing, wearing blue polo shirt, dark brown hair — smiling, gesturing with hands as if holding something
The man stands on a grassy hill overlooking the ocean, introducing an alternative method for redefining the kilogram.
"But there is another approach to redefining the kilogram, which involves fixing Planck's constant. And it's done using something called a watt balance."
Setting: coastal park — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — speaking to camera
Text: "Watt Balance"
The man continues his explanation on the coastal path, outlining the conditions for redefining the kilogram.
"Each one provides a check on the other. And if they show good agreement and are able to bring their uncertainties down to about 20 micrograms, they may redefine the kilogram as early as 2014."
Setting: coastal park — overcast daylight
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — explaining, looking at the camera
A number appears on a parchment background, showing the actual mass of a liter of water.
"Well, if you look at a liter of water at nearly 4 degrees Celsius, it has a mass of 999.975 grams."
Setting: n/a — n/a
Text: "999.975g"
The man concludes his thought, expressing admiration for the precision of early scientists.
"214 years ago, scientists were able to create an artifact that was correct within the margin of error of a grain of rice. Now that is truly remarkable."
Setting: seaside — overcast
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — smiling, impressed
The man speaks to the camera in a cemetery, adding a final point.
"One last thing, I should point out that it took an international collaboration of scientists to create the silicon sphere."
Setting: cemetery — overcast
People (1):
• standing, wearing dark blue t-shirt, dark brown hair — speaking directly to the camera
The historical illustration of Antoine Lavoisier is shown again as the narrator makes a final, clever connection.
"Well, in 1787, that was none other than Antoine Lavoisier. So he's been involved in the definition of a kilogram from start to finish, or from cradle to grave."
Setting: illustrated study or lab — soft, directional
People (1):
• standing next to a table with scientific apparatus, wearing brown coat over a decorative waistcoat and dark green breeches, white, powdered wig style hair — stoic, looking to the side
Text: "Antoine Lavoisier"