James Vincent

So, for example, the meter used to be based, as the kilogram was, on a physical standard. And eventually they found that this was too imprecise. So they moved it to this sort of definition based on the distance traveled by light. So it's essentially it's tied to the speed of light.

So this is sort of the big project of the System International, of the metric system, is that over the centuries, they started off as physical standards, and they've all become these standards based on universal physical constants. And the idea is that by doing that, the units become unchanging.

So this is sort of the big project of the System International, of the metric system, is that over the centuries, they started off as physical standards, and they've all become these standards based on universal physical constants. And the idea is that by doing that, the units become unchanging.

So this is sort of the big project of the System International, of the metric system, is that over the centuries, they started off as physical standards, and they've all become these standards based on universal physical constants. And the idea is that by doing that, the units become unchanging.

So they're based on the speed of light, they're based on the spin of atoms, they're based on things that we think are the same throughout the universe.

So they're based on the speed of light, they're based on the spin of atoms, they're based on things that we think are the same throughout the universe.

So they're based on the speed of light, they're based on the spin of atoms, they're based on things that we think are the same throughout the universe.

Well, each unit tends to have its own origin story. And some of them are like the metric system. We can say exactly how that came about because there's modern records of it. For things like the qubit, well, we just know someone decided to base that on qubits. the length of their forearm.

Well, each unit tends to have its own origin story. And some of them are like the metric system. We can say exactly how that came about because there's modern records of it. For things like the qubit, well, we just know someone decided to base that on qubits. the length of their forearm.

Well, each unit tends to have its own origin story. And some of them are like the metric system. We can say exactly how that came about because there's modern records of it. For things like the qubit, well, we just know someone decided to base that on qubits. the length of their forearm.

For the inch, for example, we know that that was a sort of common unit used throughout Europe and was usually taken to be the width of the thumb. And now that sounds like a short inch, but if you take the width of your thumb and you press it down flat on a surface and measure the exterior across the widest part of the knuckle, that will be an inch. And we had actually...

For the inch, for example, we know that that was a sort of common unit used throughout Europe and was usually taken to be the width of the thumb. And now that sounds like a short inch, but if you take the width of your thumb and you press it down flat on a surface and measure the exterior across the widest part of the knuckle, that will be an inch. And we had actually...

For the inch, for example, we know that that was a sort of common unit used throughout Europe and was usually taken to be the width of the thumb. And now that sounds like a short inch, but if you take the width of your thumb and you press it down flat on a surface and measure the exterior across the widest part of the knuckle, that will be an inch. And we had actually...

There's a very interesting bit of law from King David of Scotland, which I think of about the 13th century, where he says that if you want to define an inch, you need to take the thumbs of three men, one small, one medium, and one large. And then you take the measurements of all their thumbs, and then you add them up, and you divide it by three. And that gives you the average length of the thumb.

There's a very interesting bit of law from King David of Scotland, which I think of about the 13th century, where he says that if you want to define an inch, you need to take the thumbs of three men, one small, one medium, and one large. And then you take the measurements of all their thumbs, and then you add them up, and you divide it by three. And that gives you the average length of the thumb.

There's a very interesting bit of law from King David of Scotland, which I think of about the 13th century, where he says that if you want to define an inch, you need to take the thumbs of three men, one small, one medium, and one large. And then you take the measurements of all their thumbs, and then you add them up, and you divide it by three. And that gives you the average length of the thumb.

So people were aware that there was variation within body parts, and they tried to mitigate this in various ways. Some units have really, really ancient origin stories. For example, the carrot as a unit of sort of gems, of precious gems that actually comes from the carob seed, which is a seed of a tree

So people were aware that there was variation within body parts, and they tried to mitigate this in various ways. Some units have really, really ancient origin stories. For example, the carrot as a unit of sort of gems, of precious gems that actually comes from the carob seed, which is a seed of a tree

So people were aware that there was variation within body parts, and they tried to mitigate this in various ways. Some units have really, really ancient origin stories. For example, the carrot as a unit of sort of gems, of precious gems that actually comes from the carob seed, which is a seed of a tree

which is sort of spread across Arabia and was used by Arabian traders in order to measure in their scales the weight of precious metals and gems. Because the seed was so consistent in size, it was the same each time it was created. That meant that it could be a useful marker. So yeah, some units we have stories for, some units it's not so clear. They change over time.