Measure for Measure

The history of measurement

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Quantifying our lives

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Quantifying our lives

1:35When you last weighed something in kilograms, did you detect anything different? Well, if you're as finely tuned as the standard kilogram itself, you may have noticed it wasn't quite the same. The kilogram was changed by about 50 micrograms in the last couple of years to keep up with the demands of universal standards of weight. It may seem finicky until you realize just how much our lives depend on precision measurement.

2:09To give you an idea of how much, well, consider that the call for consistent standards was a public rallying cry in the heated chaos of the French Revolution. There was this document that was created called the Cahiers de Doléance, the Notebook of Complaints, that was collected by the sort of revolutionaries to say, OK, what are people really annoyed about? And measurement is mentioned there as 14th most frequent object of complaint out of 50 or so. So it is more complained about than infringements of personal liberties or injustice in the court system.

2:42Yet, why do fights over measurements continue? While the U.S. still works with imperial units, nearly all the rest of the world uses the metric system. Where have all these strange units come from, and why do we need a kilogram defined to a few dozen parts per million, and time calibrated to a billionth of a second? This is Big Picture Science, and I'm Seth Shostak. I'm Molly Bentley. In this episode, From Light Years to Leap Seconds, we look at the history of efforts to quantify our lives and why there's always room for greater precision.

3:14This episode is Measure for Measure. The world can be a messy place. One way we can enforce a little order is by quantifying things. Imagine the ambiguity of going to the store and saying, can I buy, you know, some cloth? As opposed to saying, I'll have a yard of cloth, please.

3:46And we may think of these handy units of measure, yards, pounds, miles, as being somehow nature's fundamental units and immutable. A lot of us think about units of measurement as somehow natural. That they are just sort of, you know, derived from the natural world, and they are unchanging, and they are ancient. And a lot of units of measure do have long histories, certainly, but they are essentially arbitrary. They are a thing that we make up to make sense of the world. For example, the units of measure depend on where you live.

4:19In the U.S., we still work with imperial units for distance and weight, that is, feet, miles, and pounds, while most of the rest of the world uses the metric system, meters and kilograms. I find the history of where these units came from fascinating. For example, many are the product of the French Enlightenment and reflect the admirable ambitions of European scientists to rationalize the bizarre systems and weights and measures that they had inherited from the Middle Ages. I wanted to learn more about that.

4:50My name's James Vincent, and I'm the author of Beyond Measure, the Hidden History of Measurement. Seth and James tell the story of measurement and begin by diving into the history of units and how they were defined and redefined over the centuries.

Standardizing the ancient world

5:03James, we take it for granted that when someone tells me that a room is 20 by 30 feet in size, that I'll know what that means because I know how long a foot is. But that's a relatively new idea, is it not? The idea that you would know for certain how long a foot is is relatively recent. The idea that you would communicate by talking about a unit of measurement of some sort has been around for a long time. You know, we have had units of measurement that, well, you know, the earliest records go back as far

5:35as the earliest records of humanity, as far as recorded history goes back. You know, as long as people have been getting together in groups and building societies, they have developed systems of measurement of varying degrees of accuracy. The reason for this, I think, is, you know, as you point out in your example, measurement is a form of communication. Measurement is a type of language. It's a way that we share information with one another. And so measurement is, you know, integral to human civilization as we know it. But over time, we have got much more accurate

6:05in how we deal with measurement. Well, maybe you can give us some idea of how radical the idea of standard measures of, say, distance or dimensions or weight really are. What problems would I face as a citizen of the Roman Empire, you know, 2,000 years ago, that I don't have to face today? Well, the Romans were actually pretty good when it came to units of measurement. They had one of the more sort of developed systems of measurement in the ancient world. Because measurement is this sort of function of power,

6:35essentially, you know, it's how you build a structured society. Looking after units of measurement and standardizing them was often seen as a sort of responsibility of rulers, leaders, whatever they may be. You know, it was something they would do in the same way that they had to look after the roads or they had to punish citizens. You know, measures had to be standardized for them to be useful. You know, you go down to the market, you don't want people measuring things out in different standards than you're using. So the Romans were actually pretty hot on that sort of stuff. They had things like market inspectors

7:07who would go down to the local, you know, the local market basically and check that the units were all basically right and what they should be. What the Romans couldn't have done, or what they wouldn't have done well, was sort of communicating those measures over long distances and in daily life as well. So, you know, one of the things that the science of measurement has achieved, as well as greater accuracy in sort of high precision science, is greater standardization in everyday life. And that's partly due to, you know, the progress we've made through globalization

7:38and through the consumer market. You know, we now have a very rigorous system of standards that are implemented in every country and across the world as well. So yeah, the Romans would have had a much trickier time communicating units over great distances, but they were relatively good on it for the ancient world. You know, they really cared about measurement. Sounds like you can't really write a book positing that the decline and fall of the Roman Empire was due to the lack of good standards. But your book really picks up steam at the end of the 18th century.

8:09Yeah. When, you know, the French Enlightenment and all, when people wanted a new system of standards, did they want that something that, I mean, was that something that only egghead scientists wanted to do? Give me some idea of the societal need for a rationalizing measure. Well, I mean, it's funny you bring up the decline of the Roman Empire because when the Roman Empire declined, measurement standards declined, specifically in Europe. You know, European measurement standards owe a lot to the Roman Empire. One really obvious example of that is that there are so many countries in Europe

8:40and in America as well, of course, who have a unit based on the pound. And that comes from the Latin Libra Pondo, a pound by weight. That was the Roman unit of weight. And when the Roman Empire disintegrated, measurement became diffuse as well. You know, different cities would start developing their own standards because there was not this central political authority to enforce standards across a large geographical area. They would tend to vary. This becomes a problem.

The French Revolution and units

9:08And, you know, as you say, in the late 18th century, this has become a real crucial problem. The country where it becomes the biggest problem and the most relevant for our discussion today is in France because this is where the metric system is invented during the French Revolution. OK, but it strikes me that, you know, this rationalization of measurement wasn't done by the British or the Italians or even the Americans. It was done by the French. Why was that? Well, measures in Ange-Régime France

9:39were a particular mess. Actually, the Brits at the time had a pretty decent system of measurement. It wasn't fantastic. It wasn't as good as the metric system would be, but it was pretty good. In France, though, it was partly to do with the political structure of the country. So obviously, France was still running on the feudal system at this time, and it had a lot of devolution of powers. So sort of the authority over how the country was run was devolved to local lords. This included power over weights and measures.

10:12So often you would have standards that were only enforced within a very small area. Because of this, there was a huge variation of measurement in France. There was, you know, one estimate that there were more than 1,000 different units, named units in the country at the time, and more than around 250,000 different variations. So you would have a unit like the pint, for example, the pinth, you know, a unit of capacity. We're familiar with it today. But that would range in size from less than a litre in one city to more than three and a half litres

10:42in another city. And this created a huge amount of sort of economic friction and confusion for the citizens as well. So at the time, in the run-up to the revolution, for example, there was this document that was created called the Cahier de Dolance, the Notebook of Complaints, that was collected by the sort of revolutionaries to say, OK, what are people really annoyed about? And measurement is mentioned there as the 14th most frequent object of complaint out of 50 or so. So it is more complained about

11:13than infringements of personal liberties or injustice in the court system. And it was because it hurt people's lives on a very real, tangible basis. You couldn't trade easily. You know, if you were taking your cheese from one part of the country to the other, how would you know how it was going to be weighed and paid for at the other end? And there was also a lot of exploitation by feudal lords. You know, they would collect taxes from peasants using bushels that were larger than the ones used by the peasants in the markets. So there was this sort of pre-revolutionary slogan

11:43that went around and was very popular. And it was a demand for one king, one law, one weight, and one measure. So this was how important measurement was to people's everyday lives. I would imagine that would be a strong competitive pressure for the pubs to redefine the pint very locally in their pub and keep making it bigger and bigger.

Tying measures to nature

12:03The original idea at the end of the 18th century was to tie these new measures to something in nature, right, the basic unit of length, a meter, was to be a fraction of a meridian, you know, the line connecting the poles, if you will, so that a meter would be one ten millionth of the distance between, well, say the North Pole and the equator. Was that just a matter of idealism? Nobody was going to put meter sticks down between the North Pole and the equator. Well, there were a lot of a few different suggestions for how

12:34to redefine the meter and some of them had their origins as ideas going back before the French Revolution as well. This was something that people had been thinking about for a while, that there should be one standard unit of length that was derived from something that was, you know, fixed. And people thought, well, what is a better authority than the dimensions of the Earth itself? And so, it was sort of arbitrary in a way, right? There was no real reason to be like, well, let's measure North Pole to the equator, one ten millionth

13:05of that distance, let's do it. You know, there's nothing really special about that, apart from it makes a good story in a way. And it was this sort of transition in authority that shows how the creation of the metric system was really a political revolution as well as a scientific one. So, to give an example of this, you know, one of the standard units of length in France prior to the invention of the metric system was known as the pied du roi, which is French for foot of the king. And as the name suggests, this was a unit

13:35that was supposedly derived from the length of the king's foot and had its origins going all the way back to the ninth century to Charlemagne. And obviously the revolutionaries, they are rebuilding society, they are getting rid of the authority of kings, they are republicans, and they were thinking, well, why would we base something as fundamental as needful in everyday life as a unit of measure on the body of the king? Let's base it on something scientific, rational, on something universal, and so that's why they went for the earth itself. So it's really,

14:05you know, it was a decision that was about embodying political ideas as much as it was scientific ones. Surely, though, they would run up against some inconvenient truths here, in particular that if you say, okay, it's one ten millionth of the distance between the North Pole and the equator, the facts are that the assumption there is that the earth is a perfect sphere, right, which, of course, it's not, and they even knew that it was not. So, you know, did they address this problem, or did they just say, well, it's an approximation? Well, I mean, it's a really

14:37interesting one, because at this time, you know, the GeodC of the earth was developing. People knew it was not a perfect sphere. They knew it was an oblate spheroid. They didn't quite know how the deviations would work when you were comparing one quadrant to another quadrant, one part of the meridian to another, and in a way, they did just say, yeah, it is arbitrary, we're just going to go for it, because they picked, the line of meridian that they picked goes through Paris. So they, you know, rather than picking some other line, they were just like, well, we'll just have this one, it's going to be French,

15:07okay? And actually, that was a really historically important decision, because it annoyed a lot of other countries who were like, well, no, it should be the London meridian, it should be the Washington meridian. You know, this was one of the reasons Americans initially didn't get on board with the metric system. Thomas Jefferson said by picking the Paris meridian, the French have excluded every other nation on earth from this sort of community of measurement. So they knew that it was a bit of an arbitrary decision, but what I sort of learned whilst writing this book and doing this research is that

15:38often in metrology, specifically in the creation of the metric system, the narrative is more important than the science in some ways, because the measurement that they took took seven years, it took two astronomers to do it, they did this huge survey right across Europe, they did it in the fire of the revolution, they got arrested several times, they thought they were sort of monarchists in some way, the peasants did, but by the time they got this measurement it was seen as this huge scientific achievement, it was seen as this great arduous journey

16:08and that gave it authority in a way. So yes, it was arbitrary, but the means of creating it gave it this heft and importance. you talk in your book, James, about the physical embodiments of some of these measures, in particular the meter and the kilogram, you know, they were actual, I mean, you could say where's the prototype kilogram and there was an answer to that and the answer was not what ten cubic deciliters of water would weigh, but the embodiment was a piece of a hunk of metal kept in

16:39a building in Paris and well tell me about those because that's really fascinating. Well, I was lucky enough to see the original meter and the original kilogram in the National Archives in Paris and where they are kept in, you know, this old mansion house that used to be an aristocratic mansion and was taken over by the revolutionaries and now very, you know, symbolically these old ballrooms are now filled with all the original documents from the founding of the French Revolution and the original meter and the kilogram there are kept in this

17:10amour de feu, this iron cabinet next to the original copy of the Declaration of Rights of Man, you know, it's this fantastic objects and I remember going to see them and talking to the curators there and I said, do you ever have these out on display, the meter and the kilogram? And they said, yeah, yeah, we put them out, people come, they don't ever really look at them and I said, well, why is that? And they said, because they don't need to see the meter because it already exists in their head and this is the thing about these measurement standards, they need to have a physical existence of some sort in order for these units to be shared

17:41around the world but in a way they sort of float free of that, they are units that we have to use for them to be useful. Now, with these physical standards, as soon as these were created, people knew there were going to be problems with them, you know, everything that you create that has everything that is physical in the world is liable to wear and tear, it will decay, it will change over time, no matter if you make it out of the strongest metal, the most durable alloy you can think of, it's going to change. This happened with all units of the metric system. And actually, over time, we have started

18:11replacing them. So we no longer use physical standards to define units of measurement, but we actually use sort of calculations based on constants of nature instead. But this has been a long process that we've been working on for many decades. Yeah, I remember reading somewhere that if you actually picked up the standard kilogram, you would change it because of the oil on your skin. time can feel elusive,

18:45expanding on one hand, contracting on the other, but at least we can count on the units of time being constant, not needing to be tweaked. Oh, hold on a second. We are still doing this sort of work today. we are further redefining and making these systems more accurate. One example of this is the measurement of time. How accurate can our clocks get? Well, it used to be that we would accept that they would gain or lose a minute over the course of a day. But today, precision has been refined to gaining or losing a second during

19:17the age of the universe. Next, the role played by astronomy, engaging time and other quantities. It's Measure for Measure on Big Picture Science.

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20:18As the standards of measurement moved away from those decreed by kings, there was an interest in tying these units to something larger than our own lives, nature. Seth and James Vincent discussed the role that astronomy played in guiding this, the ways in which the speed of light and the size of astronomical bodies were influential, and why, as physics advanced, measurement needed to be ever more exacting.

Accuracy and modern physics

20:45How units of measurement have been defined and redefined is what James Vincent covers in his book, Beyond Measure, The Hidden History of Measurement. We have moved away from having, if you will, all these standards defined by physical artifacts in Paris. Yeah. But why do we need more accuracy? I mean, so the distance from here to New York might be off by, you know, a few inches, if I can use inch here, because, you know, our meters are not exactly standardized. Would that matter?

21:17I mean, if it was off by a few inches, I'm sure people would definitely be worried about that. That would be a huge deviation in terms of accuracy. Accuracy does matter. Accuracy is fundamental to science. There is this famous quote from Albert Mickelson of the Mickelson-Morley experiment fame. You know, we were talking before we started recording about the luminiferous ether, you know, that was what their work was involved in placing in its proper context. He has this quote, he says, the future truths of physical science are to be looked for in the

21:47sixth place of decimals. Now, this quote has sort of been derided in some ways, because he was talking about this before mid-1890s, I believe, 1894 or so. He said this, that, you know, the foundations of physics are basically done, and we've got to look for the future of physics in the sixth decimal place. Now, he said this before general relativity, special relativity, before the quantum mechanical revolution came about. So he was obviously sort of misplaced in some fundamental ways, but he was also right in other ways, in that it is by

22:18looking for greater accuracy in science that we often make a lot of discoveries. And a lot of discoveries have been made in science through precision measurements, and by measuring more precisely, you know, we can discover new things. Now, I'm skipping ahead quite a lot here, but one of my favourite examples of this in the contemporary era would be the LIGO observatories, you know, the measurement of gravitational waves. You know, these gravitational waves, they are caused by huge cosmic events. The first observation of them was in 2015, then

22:48announced in 2016, it was caused by two black holes colliding. But what LIGO is, is essentially a big ruler. You know, it is these two arms, each about four kilometres long, in these pairs of observatories, and you are doing laser interferometry. So you have lasers bouncing up and down each arm, and then you measure the interference of the wavelengths and how the patterns overlap, and you can use that to make very precise measurements. But that precision is needed for those observations. Gravitational waves are so tiny, they are so minute, they are, you

23:19know, these tiny ripples in space-time, that to be measured, you need to have a measuring tool that can do so with great accuracy. And, you know, LIGO, I think, is boggling in these terms. The quotes about it, for example, it can measure the distance from Earth to the nearest star, 4.2 light-years away, to an accuracy within the width of a single human hair. So by making these more accurate measurements, we are discovering new things about science. That's why accuracy is important. What's the definition of a meter, just to pick one, one unit here, these days? I mean, if it isn't a rod in

23:51Paris, you know, what is a

Redefining the meter and second

23:52meter? So all the physical units have, yeah, they've been redefined since the 1960s onwards. The meter is now defined using the speed of light. So the meter is the distance travelled by light in, and I'm not going to pretend I know this number, I've got it written down in front of me because I thought you might ask this, in 1,299,792,458th of a second. So that is now the definition of the meter. And then that makes you ask, okay, so what is the definition of a second? Well, the second is 9,192,631,770

24:29radioactive cycles of the atom cesium-133, you know, a radioactive cycle, sort of the frequency with which the atom jumps between different stable states, basically. But this is how we measure things now. There's an office in Washington, D.C. called the National Bureau of Standards. I know that because many of my friends' fathers work for the National Bureau of Standards. But do they have much work, or have we nailed down all the important standards? Will I ever have to throw out my yardstick and replace it

24:59with a new one? To answer your question directly, are we going to change any of these units now? The answer is probably yes. The thing with these units is that although the value is the same, you know, the kilogram has been the kilogram ever since it was the kilogram. But how we derive that value, that is what changes. So the kilogram, for example, was redefined in 2019. And it used to be equal to this physical lump of metal that was kept, as you sort of mentioned earlier, in this vault in Paris. And it's now defined using

25:29Planck's constant, you know, another one of these sort of constants of nature, basically. We are still doing this sort of work today. We are further redefining and making these systems more accurate. One example of this is the measurement of time. So time, you know, used to be defined as one 86 four hundredth of a solar day. You know, just take that, divide it by 86 four hundredth, that's a second, that's fine. Then in the 60s, we got atomic clocks like this sort of definition I said earlier about the spin of an atom of

26:00cesium-133. But there are clocks that are even more accurate than that, that are going to be known as optical clocks. They're a hundred times more accurate than atomic clocks. And there is a chance, well, there's not a chance, it's going to happen. We are going to redefine the second in the next decade or so, I think, maybe a couple of decades, because this accuracy is incredibly important. You know, you think about something like GPS, for example, you know, the triangulation of location based on signals from satellites. If you want GPS to be accurate to within 15 meters

26:31of a position on Earth, you need to have accuracy in measurement, measuring time of about 50 nanoseconds. So that's a nanosecond is a billionth of a second. So 50 billionth of a second. We're already getting quite far down into the decimal places there. If you want better accuracy, you need more accurate time measurement. So time is one thing that we're completely, you know, we are going to redefine basically. However, a second will remain a second. Yeah, I remember in my youth when there were lots of stories in the press

27:01about improved measures of time. And of course, partly that had to do with the fact that this was relevant to knowing where your ship is. And that had, you know, defense implications. So it was important to keep clocks. When I was in high school, we made a trip to, I don't know whether it was, maybe it was the National Bureau of Standards, wherever. And they had, they had an atomic clock there that was keeping time. And they told us, look, this clock is so accurate that it will lose one second in a million years or something

27:32like that. I don't remember. Are our clocks today much better than they were in my youth? Yeah. I mean, those were atomic clocks, as you said, and the new optical clocks are going to be sort of a hundred times more accurate. So instead of losing a second over a million years, scientists are now talking about losing seconds over the observable lifespan of the universe. You know, that is how accurate these clocks are going to be. And the thing is, once you start measuring at that scale, you can register things that also apply to that scale.

28:02So, you know, one of the theories or one of the sort of potential applications for more accurate clocks is going to be seeing whether physical constants and laws are themselves constant over the universe's history. That's the sort of level of precision and accuracy that we're going to be able to do here. James, how did you get interested in this subject? I mean, did you, you know, pick up a meter stick someday and say, I wonder where this came from? You know, that kind of thing? I think I've always had a bent of mind that enjoys systems and that enjoys sort of works of

28:32categorization. And measurement is sort of the ultimate system. I mean, to be more direct about it, the reason I was sent as a science journalist to cover the redefinition, the kilogram, and I went to Paris. I went to the headquarters of the Bureau Internationale de Poire de Mezure, the BIPM, which is the sort of international body tasked with maintaining the standards of the metric system. And I was there and I got into all these discussions about why they were redefining the kilogram. And it was mind blowing to me. You know, I had never thought that measurement was this sort of

29:04arbitrary, you know, this artificial human creation that brings so much to modern life. I think a lot of us think about units of measurement as somehow natural, that they are just sort of, you know, derived from the natural world and they are unchanging and they are ancient. And a lot of measurements, units of measure do have long histories, certainly, but they are essentially arbitrary. They are a thing that we make up to make sense of the world. And that was what really fascinated me about the subject is that, you know,

29:35so much of modern life depends upon accurate measurement and so much of the human mind depends upon measurement. You know, I think we are, you know, you think about what are the things, the inventions that really define humanity. Language is obviously one of them. You know, mathematics would be another. But I think measurement deserves its own sort of special attention. You know, people often say in life what gets measured gets managed, for example. You know, that's a truism of the management world. But I think it also shows that measurement is a form of attention. It's how we pay attention to things

30:05in the world. And what gets measured gets noticed, certainly. So I think when you look at how measurement operates in the world, it's really fascinating to think about how it affects what we are concerned with in our own lives. When I lived in Europe, they had an expression. This was among the scientists that I talked to. They said to measure something is to know something. Yeah. In other words, without measurement, you really, you know, you're just talking through your hat kind of thing. But there are also things that you cannot measure. I mean, you know, I know we're talking mainly about the science of

30:36this stuff, but, you know, the title of my book is Beyond Measure. And I think a good part of it, especially towards the end of the book, was thinking about how measurement can also be a sort of obstruction sometimes. You know, you think you measure something and you put a number on it, but does that actually really reflect what it is you're trying to capture about that? You know, there's lots of examples of this in sort of society. You get sort of things like measurement in school with standardized testing and all the rest and like, OK, you've put a number on something, but that

31:06doesn't always necessarily reflect what it is you're trying to achieve, which is to educate people to be, you know, sort of independent in their thinking, to be curious, to have a good grasp of the knowledge. In the end, you might just teach someone to answer a test correctly, but that's not the same as teaching them to have that knowledge and apply it. So I think that's another fascinating aspect of measurement, that there are some things, you know, that you can't measure essentially.

Limits of precision

31:28What are the limits here? Are there limits to how accurately we can define some of these measures? Yeah, definitely. I think one of the interesting things about the redefinition of the measurements to not use physical standards, you know, I talked about the kilogram earlier and how that was redefined using Planck's constant. And, you know, Planck's constant is the sort of, you know, the relationship between the frequency of a photon of its energy. And it's a vanishingly small number, which I won't read out yet another long number. I think your listeners have

31:59been, they've endured enough of my very long numbers. But, you know, when they set the weight of the kilogram, they also set the definition of that constant because Planck's constant is something that you can measure with different degrees of accuracy. And with the first sort of four or five digits come out the same, but the last two or three, they tend to vary. So it's this weird, and I think this is quite difficult to get your head around, or it is for me anyway, that when we set the value of, say, the kilogram or the meter, we also set the value of

32:29that constant. So, you know, I told you that the meter is defined using the speed of light. But when we set, you know, how do you measure the speed of light? Well, you've got to measure it in a unit of length, right? Because it has to travel a certain distance. So when we set the definition of the meter, we also set the definition of the speed of light to be, you know, 299 million meters per second, 299 odd million meters per second. So, yeah, there is a limit to how accurate we can be. But as we get more accurate, we end up redefining the units themselves. So it's this weird sort of

33:00circular motion of units defining standards, defining constants, et cetera, and so on. I mean, you're an astronomer, so you've been deep in measurement for a long time. Because, I mean, one of the things that came out in my book is that, while researching, is that a lot of the first measurement comes from looking at the stars. You know, this was sort of the school of measurement in many ways, was looking at the stars and trying to measure their movements. Have you come across any sort of odd examples of, you know, measurement in your astronomical career? Well, in fact, you talk about

33:31measuring the movement of the stars. Most of the movement of the stars is simply the rotation of the Earth. So, you know, that's the basis of a lot of time keeping, right? If you go to an observatory that keeps time, like the Naval Observatory in Washington, D.C., you know, you'll see what they're called the transit telescopes. And these are very uninteresting telescopes, if you're into telescopes. It's just a tube. It might be a meter, plus or minus, whatever the air is in a meter. A meter in size.

34:02And it's just aimed straight up, essentially. Or if not straight up, at least to the, you know, the meridian that's crossing that particular location. And all it does is look at when a particular star, for example, crosses the meridian. When does it come into view of the telescope? And, you know, it doesn't stay there very long. Then it exits. But the interval between those two events, say, where it was yesterday and where it is today, that's defined as one rotation of the Earth, and that's tied into the time system. So they keep time.

34:32But as I recall, the last time I was there, they said, yeah, that's fun. Not on a cloudy night, but that's fun. But we have crystal clocks. Yeah. And eventually atomic clocks that are much, much better than that. Right? So I'm just sort of, you know, wondering where this is going to go, because the ultimate arbiter, it seems, of all timekeeping standards is astronomy. So it seems. But, you know, there are limits to astronomy. I mean, the Earth's rotation is perturbed by many, many factors. Hmm. Well, I mean, I think

35:03I think some metrologists would disagree with you there on astronomy being the sort of ultimate arbiter for time. I think since they switched to atomic clocks, there has been, you know, we still harmonize atomic time and astronomical time, but it gets a little bit trickier each time around as we get more accurate. You know, obviously leap days everyone's familiar with, but I think less people know about the fact that we now have leap seconds as well, that we have to add a second every couple of years into UTC,

35:34the universal timekeeping, you know, standard. And that is because essentially atomic clocks are now, you know, more accurate than astronomical measures of time. I've heard that some people have made an estimate of the weight of the Internet. Yes. And I'm not quite sure what they mean by that, but have you heard of this and what does it mean to you? Yeah, I think the explanation of that is to do with the sort of writing the data of the Internet, basically. You take all the terabytes, the petabytes of data, and then you

36:04write them onto a physical, you know, hard drive of some sort. And by weighing that changes to the hard drive, you weigh what the data is. Because when you encode data, you change the atomic composition of that material because you are writing data onto it, and that can apparently be measured. And I think it was about 50 grams or so was the eventual sort of measurement that that came to. Yeah, that sounds like an appeal to E equals mc squared, which relates energy and mass.

36:34And, you know, if you want to write a bit on a hard drive, there's a certain minimum amount of energy that it takes to do that. Yeah. So in that sense, you could say, well, the Internet, which has so many, you know, terabytes of data, whatever it is, that represents an energy expenditure just to write it once onto all those hard drives that, you know, equates to this amount of mass. But that sounds like something that only a physicist would care about. But, you know, it's a lovely example of trying to measure something that is otherwise intangible, which

37:05I don't know, it's sort of ridiculous thing to say, but it's gorgeous as well, because, you know, it speaks to this, you know, this theme throughout my book that we are a measuring species, that we love to put a number on something. We think by understanding it, we think by putting a number on it, we understand it. You know, you referenced your scientific friends earlier in the conversation who said, you know, probably they were paraphrasing Lord Kelvin, the famous quote about until you can measure something, you can't understand it. And when you do, you have some understanding of it. But measuring the internet, I mean, it's sort of ridiculous, right?

37:36It's, it's inherited, it's sort of counterintuitive, it makes no sense. But we love to do it. We love to measure things. We'll never stop. Up next, Seth and James in a spirited debate about the virtues of metric versus imperial units, and why the author thinks that the U.S. won't commit to a switch to metric.

38:07I think of America as this sort of metric figure wearing an imperial mask over the top of itself. Well, you won't have to wait much longer for more inch by inch discussion in this episode of Measure for Measure on Big Picture Science. Every Sunday, we cover the week's tech news on This Week in Tech. Hi, this is Leo Laporte of

38:37the TWIT Podcast Network, inviting you to join me, Devendra Hardwar, Larry Maggett, and Alan Malventano as we say goodbye to a legend. The man that helped me start TWIT, my mentor and dear friend who passed away this week, John C. Dvorak. We'll also talk about the weirdest AI hack ever. That's this week on TWIT. You'll find it at TWIT.tv and wherever you get your podcasts.

Metric versus imperial systems

39:11Well, as new standards of measurement were established, the world split into two camps. Those who adopted the new metric system, which is to say most countries, and the few whose everyday activities still stayed with the imperial system, like the United States. Seth, I remember in early middle school when teachers said that we were switching to this thing called the metric system, and it was essential that we learn these new units, you know, centimeters, kilograms, and so on, because everything was about to change.

39:41Now, I was young enough that it wasn't clear to me why we were doing this, but like the other students, I diligently learned these units, which wasn't hard because it's a base 10 system, as you know, and then nothing. The big switch to metric never came. Yeah, well, I remember that, too, and I kept waiting, Molly, for all the signs along the highways to change from miles to kilometers. Well, I'm still waiting, and I wish they would do it because the computation is so much easier in a base 10 system.

40:11Well, that brings us to this next conversation where you and James debate the merits of the metric system, beginning with James following up on an earlier thought. But I want to pick you up on something, because when you talked about that telescope, you said it was about a meter long. Now, I want to know, this was a big part of my book, was metric versus imperial, which is the quote-unquote better system, which is the dominant system. Obviously, I'm from the UK. We use a little bit of both. You're from the US. You're still imperial. Do you think in metric? Do you think in imperial?

40:42I tend to think in, it depends. Maybe I should preface my answer. That's never a good preface, but it does depend. Obviously, as soon as I started studying physics, you know, in 12th grade, as it were, then everything was in metric. And metric is great because it's a decimal system, right? You know what fractions were. Whereas, you know, imperial, I mean, you have a pound, but it's divvied up into 16 pieces called ounces. That's pretty inconvenient. So I definitely preferred the metric system.

41:12Do you think in metric or imperial? I still think in metric. I really do. I mean, if I see somebody, I don't say, oh, you look like you weigh about, you know, 50 kilograms. But for anything that's, if you will, quantitative, if I'm just trying to reckon, you know, for example, how far out into space have our television signals reached? I do that all in metric, of course. Yeah. I mean, we're still a bit of a muddle here in the UK because we obviously, we are officially metric, but we have a lot of non-metric weights and measures

41:45used in shops, for example. We still have pints in pubs. You know, no one's ever going to get rid of that. And it's become this cultural issue. You know, when Boris Johnson was still prime minister, he promised that he would bring back imperial measures. And there was this sort of huge hue and outcry over this. And everyone was like, what, we're going back to the, you know, we're going back to the Stone Age next. What's going to be, it's become this real cultural issue. And I think it is similar in the US as well, right? In that, like, you know, if you had, I think it was Lincoln Chafee,

42:15right, in 2016, when he announced he was, his presidential bid, he said, we're going to go metric. And he was absolutely, he was decimated in the press, shall we say, to use a appropriately metric unit there. You know, he was really torn apart for that suggestion. And I was really shocked. I, you know, it's still such a live issue. Yes. Yes, it was very much so. Well, I mean, it isn't based on the inherent merits of metric versus imperial units, of course. It's just what people already

42:45know. And you're changing something they already know to no benefit for them. I mean, I've heard people say, look, actually a pound is better than a kilogram because if you're giving somebody your weight, like your doctor or whatever, if you use pounds, your answer is more precise than it is if you say I weigh so many kilograms. I mean, they'll point out the advantages to the old units, which are, you know, not inherent advantages, but in terms of their application, obviously after, you know, centuries and centuries of

43:16these imperial units, you know, they become adapted to the requirements of daily life. And that's the advantage. Yeah. Yeah. But one thing I would like to just mention, this is related, obviously, I don't know how many of your listeners will be aware, but, you know, the U.S. is metric. Like, I know it's, you know, ever since 1893, that was the year of the Mendenhall order, I believe it was called, the foot, the yard, the ounce, they have all been defined using metric units. So, although, you know, I think of

43:48America as this sort of metric figure wearing an imperial mask over the top of itself, because although everyone is dealing with gallons and ounces, those are defined using metric units, you know, so in the secrecy of labs and in factories, everything is really metric, but people don't like to talk about it. Well, they don't like to use it either. I mean, when the captain of that aircraft that you're flying across the Atlantic comes on, it's an American, you know, airline, he'll tell you how many thousands of feet is the altitude of the

44:19plane. Feet. He's not going to tell you in meters. And, of course, in fact, the whole thing is set up for him to fly at 30,000 or 33,000 or something. Some, you know, very, well, obviously, it's an acknowledgement that the imperial units have precedents in aviation, you know, just about anything else there, too. I mean, nobody talks about how many kilometers it is from Washington to New York. No, but they do go on 5k runs or they go on 10k runs. And if you're in the military, you

44:50talk about clicks. How many clicks away is this? And that's because the U.S. military has been metric for a long time because they needed to harmonize with other countries' military forces. You know, nine millimeter bullets. It's a very American thing in many ways. And yet it's very metric. It is. It is. But a lot of these examples have a tinge of, well, elitism, as they use the word here, right? Oh, you're going to tell me in kilometers and not in miles. Right. You know, look, you know, I'm just Joe Blow. Tell me in miles.

45:21Yeah. It's not always appreciated that it's a far handier system in the end. So what do you figure is going to happen here? I mean, the metric system, you could say, you know, that's a couple of centuries old now. Does it need any change, any major changes, or is it kind of arbitrary what units you choose? I think it's sort of arbitrary. People ask me sometimes, what do you think is better, imperial or metric? And I think there are certain qualities embedded within each system

45:52that has benefits and drawbacks. So one of the big ones, and we've mentioned it several times, is the fact that metric is decimal. It works in base 10. Whereas imperial units or U.S. customary units, I should use their proper name, as it is in the U.S., are, you know, base 12 or base 16. And those are, they can be a little bit simpler when you're working out fractions. You can easily half, third and quarter a unit if it's in the U.S. customary or imperial system. So there are certain differences to them. But for me, what makes measurement

46:22useful, and this goes back to what we were talking about in the beginning, that measurement is a language, it's a form of communication. What makes it useful is if it's consistent and if it's understood. And this is, you know, like your example from the airline. A pilot says we're 30,000, we're cruising at an altitude of 30,000 feet, 33,000 feet, whatever it is. They say that because they want to communicate to their audience and they want to get that information across. That is what makes measurement important. In the U.K., I think this is changing. So younger generations in the U.K., they come up firmly metric. They're taught metric in school. That's what they know.

46:55And I think in the U.K., at least, we will gradually become a fully metric country and we'll get rid of, you know, we still talk about weight in terms of stones, for example, you know, which is such an archaic unit to use. But it's what people know. But they are forgetting. And the younger generations will become more familiar with it and they'll just push it out of the sort of cultural language, as it were. The U.S., I think, I don't know whether the U.S. will ever go metric. I think there is something, well, maybe in the long, long term, but I can't see it

47:26happening in the short term because, I mean, they're just, you know, U.S. exceptionalism, right? There is just this strain. I'm sorry. I'm not, I don't want to have a go at you for this. I know you're not personally responsible for this, but there is this strain in American culture and politics that says we are the only one and we are the important one and our system is right, right? And obviously, you know, I work with Americans all day. I talk to them all the time. Wonderful, wonderful people. Great country. But there is this strain within it, right, of we are the best. And I think that's not so apparent in

47:57other countries. No, you don't go to, you know, you don't go to France, you don't go to Germany and see people saying, oh, we should go back to the old ways. They're very happy with metric because they know about the benefits it brings in terms of harmonization.

Manufacturing and trade arguments

48:08Sorry, you go on. No, no. But I put to you the fact that, yes, American exceptionalism may be the zero order term here. But on the other hand, you know, if I were making a defense of America's continued use of inches, for example, I would say, look, there are tens of thousands of machine tools out there. Yeah. And they're all set up to work in inches. Right. So we're going to we're going to mill this to two thousandths of an inch or something like that. Yeah. And if you want to change that all to metric, somebody is going to pay the

48:38price in loss of competitiveness for a while because, you know, they don't know how the machinists don't know what they're doing. Well, it's funny you should bring that up because that is one of the huge reasons that America never went metric. You know, we talked about this a little bit, but, you know, when the metric system was being created, there were a lot of fans of it in America. Jefferson was the big one. You know, obviously he was a huge francophile. He was minister of France and he loved metric. He tried to get a set of metric standards over to the U.K. Sorry, sorry, to the U.S. from France.

49:09And actually, the funny thing was that they got waylaid by British privateers in the Caribbean. That's the reason America never had metric standards during that period, because the ship got captured by these privateers. Anyway, but during the 19th century, when metric really started spreading around the world, it was adopted across Europe and South America. Americans, politicians, lawmakers started saying, well, why don't we adopt it as well? And the big argument, the winning argument against it being adopted was the machine tool industry, was the manufacturing base that America had built up at this time, which was just gargantuan, just so profitable, so

49:43powerful, so integral to the country's success. And it was this wealth, this capital embodied in these machines that meant that America went metric. And in a way, it's still that situation today. For as long as America continues to be, you know, the global superpower, it can sort of call its own shots. One of the reasons the UK went metric was because we had lost a lot of power, a lot of wealth, and we wanted to have better trade with the rest of the European continent. And so that meant adopting the same

50:13measures that they did, because it made trade easier. America can sort of call the shots, and it can afford to absorb that difference in that friction between those different systems of measurement. So when you get rid of imperial measures, that's when we'll know America has properly declined.

50:30Well, James Vinson, it's been a real pleasure to speak with you. It's been wonderful to talk, Seth. Thank you so much for having me. James Vinson is the author of Beyond Measure, The Hidden History of Measurement. Well, Seth, I found it very interesting to learn how politically driven, or maybe you would say nationalistic, the motivations for establishing standards of measurement. The idea that, you know, that it was based on the foot of the king, the idea that the French wanted the meter based on the meridian that passed through

51:02France, much to the ire of the Brits and others. Well, I think that's an old story in the sense that we just don't like to have other countries impose their culture, if you will, no matter what it was, on us, unless it's a culture that, you know, like polka dancing or something like that, that we can adopt without any controversy. But then conversely, people after the French Revolution didn't want their measurements to have anything to do with the king. Yeah, well, the metric system doesn't have anything to do with the king. It was based on, you know, the

51:33dimensions of the earth. So, you know, that was the idea. These French intellectuals, the French scientists of the Enlightenment, they wanted to base these units on something that you couldn't say this was French or it was Swiss or German or American or anything else. It was just a measurement that was consistent with what nature gave us, in this case, the size of the planet. This show would not be possible without

Reflections on national standards

52:16the precise efforts of senior producer Gary Niederhoff and assistant producers Brian Edwards and Shannon Rose Geary. I am the executive producer of Big Picture Science, Molly Bentley. And I'm Seth Shostak, senior astronomer at the SETI Institute. We'd like to give a big thanks to our listeners and to our Patreon supporters. Original music in the show was created by Dewey DeLay and June Miyake. This episode of Big Picture Science that examines the history of the kilogram, meter, gallon, and inch is measure for measure.

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