It is very interesting to know where the standard comes from. It is also very good to know that the physical standard is being moved out in exchange for a fundamental measurement. Having a physical standard can lead to many problems that would be horribly detrimental to our current system. Everything based on a Kilogram would then be somehow incorrect. With a fundamental standard. this cannot happen. The force will not change overtime, it will not loose mass, and it cannot be corrupted. A fundamental standard will ensure that things will run smoothly.

This was so interesting because I have never though of what weigh actually is. I see it on many products, but never thought that the world must have a single standardized version of a "kilogram". It's crazy to see how some scientists are changing the standardized unit from something tangible to something expressed in words.

I think it's crazy that this plum sized kilogram weight is the only physical measure we have to accurately measure a kilogram. That is insane that there used to be 250,000 different measurements.

I think this was a very interesting podcast. It brings up a lot of interesting things that people never think of. Like the ruler example at the beginning of the podcast, how do you know that an inch on my ruler is the same inch thats on your ruler? Or even where any of these units came from. It is amazing how these units have impacted businesses and the trade industry as a whole.

I found this podcast very interesting. You never really think about how the first meter or kilogram was measured. Or how the standard units came in to being in general. I learned a lot from this podcast that I didn't know before. I never really thought how the creation of the SI units has impacted international trade and commerce and how without the SI units, international trade may not even exist. I didn't know that the creation of the SI units had coincided with the French Revolution either. All in all, I found this podcast captivating and enjoyable.

Interesting how the throw of a rock was enough to get us by, until the French revolution. However, it isn't much different than what they came up with to make the kilogram. The only upper hand it had on the throw of a rock measurement was how we got it (the circumference of the Earth/10,000 and some other mathematics mentioned). Yet, that was all that was needed to keep everyone on the same playing field. Although, the weight now keeps on changing from the original Kilogram, which leads me to believe our method to standardization of measurements is flawed. The solution is a theoretical standardization, rather than a physical standardization.

The effects highlighting the definitions at the beginning are creative but slightly disconcerting, but I think the other effects add interest. The historical reason for units of measure is fascinating, as well as how their definitions have changed since the times of the French Revolution, with the advancement of science. I would never have imagined that the original kilogram still exists or that there is such a systematic network of connections to it. However, it makes sense that the standard would lose mass over such a long time under varied circumstances. I'm glad that someone is working on defining it more fundamentally, and magnetism is probably more practical than the idea that popped into my head, defining the kilogram by a certain number of moles of some element.

Wow. What a lot of people whining about the audio effects. I hope these duds will put down whatever stupid tools they use in their boring jobs and go to school for ten years and then spend another twenty working in a high tech metrics lab gaining experience. Then I hope they go on to make the worlds roundest tennis ball and win the Nobel Prize for doing it and then mail it to me here. If that actually happened I promise that I will give it to my dog.

That woman's voice was so annoying!

I love this show, my wife does as well and I spend every minute that I'm in my car listening to one podcast or another. This one is a frequent player. I have a bit of an issue though with your normally very comprehensive reporting. There are a number of other proposals to solve the disparity in the weight difference. One, which makes probably a better Youtube video even is the Avogardo experiment. This is a proposal to use a specific number of Silicon atoms, which are presented as a pure block of Si which has been ground and polished into a sphere with amazing precision. One good video is this: http://www.youtube.com/watch?v=ZMByI4s-D-Y.

I think the one other item of note which wasn't mentioned is that this is the only SI "base" measurement which is actually a multiple of another measurement (1000 grams in a KG). Interesting that here, they don't have a "Le Grand G" or have redefined the SI standard to be the gram. I believe originally this was largely because the gram was too hard for anyone to actually accurately make, and since the original definition was "The mass of one cubic meter of water" (also adds in the question of water purity, but....), it was easier to stay with that through time. We now do have the precision to adequately and accurately define and make a SI gram standard, so maybe it's time to switch? (Maybe we could scrap the whole thing and just define a pound and go on with life, :) )

I would finally, like to answer one question I see in the posts here. The term being used is "Le Grand K" -- French which is almost literally -- "The (Huge/Important/Grand...) 'K'". While the question of "Le Gramme K" actually would make sense since this is the reference "KiloGRAMME", it's not what SI or CGPM/BIPM actually call it.

One of the guys sounds like Neil Flynn.

Roger - Australia from Queensland, Australia:

We in the U.S. are using "SI" units. Our National Institute of Standards has defined the pound as 0.453_592_37 kilograms since the 1950s. But, don't tell us Americans that. We'd freak out we found out that our American measurements were based upon some Frenchy system. After that, it's only a small step to sipping wine, wearing berets, and playing soccer.

Thomas Jefferson (the third President of the U.S.) tried to get the U.S. to adopt the metric system. Under his influence, we were the first country to adopt a decimal based currency (100 pennies to the dollar). Since currency was based upon the weight in precious metals. It made sense to use a decimal based unit of measure as our official unit of measure. Unfortunately, the French Revolution turned violent, and the metric system became synonymous with the guillotine.

What do they call the International Prototype of the Kilogram (IPK)? In the show they keep saying it, but I can't find it on Google or Wiki. "Le Gramme Ka"?

To the 'keepers of standards,' it's not just about accuracy or about stuff, it's about precision and universality. Measurements must be accurate but also precise (more significant figures). I hope that the lay audience could appreciate the creativity of physicists in finding physical processes capable of ever-more precise values of standards. Hopefully, someday we'll learn empirically what we believe to be true: that physics here is the same as physics everywhere in the universe. ET: are you listening??

'Those effects aren't just gimmicks. They serve a communication purpose. And this is why I love Radiolab.'

I found it hard to comprehend what they were saying due to it. I'd say that's a failure.

I usually enjoy the computerized voice overlay effect, but its use during the scientist's revised definition of the kilogram obfuscated what he was saying, making it incredibly difficult to understand. Not the best moment for a show that takes pains to effectively communicate science to public.

I thought the voice effect on the standard units was a fun and effective touch, as a counterpoint to the negative feedback I'm seeing here. It made me think of Glados from the Portal series. People are often quick to point out what they dislike but are less inclined to offer praise when they expect a good/great product/service. Thank you Radiolab, for being awesome.

I would also like to comment on the voices, noises, sounds, whatever you want to call them. They do make it difficult for me to understand what is being said, as I have problems picking voices out of the clutter. I am absolutely useless at a party and just tend to avoid them since I can't understand what people are saying. I will admit your bits and pieces aren't nearly as bad as some radio shows where they multiple hosts and they talk on top of each other. Great piece in any case.

Hang on... so French mathematicians made their original "kilogram" starting with a linear measure, the meter (which they then cubed). And a meter was one ten-millionth of a quarter of the earth's circumference.

What unit of measure did they use to find the earth's circumference? For that matter, what METHOD did they use to measure the earth's circumference?

at around 11:00 there is a shrill operatic voice that hurt my ears while listening on headphones at a normal volume. please don't

Hey nice samples from the Swingle Singers in the soundtrack. For fellow fans - their 1964 Jazz Sebastian Bach albumn is available on CD.

As I have come to expect, the content of this show was both insightful and amusing.
That's pretty much a given these days. I would, however, like to add my 2¢ regarding the sound design.
Listen not to the nay-sayers, J & R, the operatic singer and the repeated overlay of formulas worked brilliantly for me.
Great show; keep up the good work.

There are also other researches trying to re-write the deffinition of a Kilogram, like the "Avogadro Project" for instance. I just think that you should have touched the subject and spoken about the other researches

http://www.youtube.com/watch?v=RPBro9mzoVM&list=PL2ACE88CE29292ECA&index=2

Bach Fugue no. 2 in C minor from the Well-Tempered Clavier!

Hey guys, you say in the story that the French create the KG by taking one ten-millionth of a quarter of the earth's circumference ('the meter'), cubing it, filling it with water, taking the mass of the water and then creating a metal cylinder with the same mass. Given that this procedure should yield the same mass every time it is invoked, the fact that the original unit of measurement 'lost weight' shouldn't have been a cause for panic (or even necessitated the use of the 'magnetic force' measurement) since anyone could simply reproduce the initial process that forged the first kg, producing the exact same mass as before.
Is there something wrong with my logic? Please email me, as I'm curious to know!

Ben Vernia, a straight-edge is easy to make. Make two sides parallel (it's easy to gauge that with a caliper) and lay it first on one edge then the other on a flat surface. When no light gets underneath in either position, the surface is flat and the straightedge is straight, killing two birds with one stone. There are methods like this for creating all measuring instruments; they don't derive their accuracy from some "original perfect" instrument created by God.

(Also, the "world's roundest object" is at the CSIRO/NMI site just 4km from here - they have one of the duplicate 1kg standards there. The video shows the young project manager, not the older bloke who actually made it round. The world is running out of his kind of person)

As a weekend woodworker, I've sometimes thought that there must be a genealogy of tools - particularly straight edges. In order to create a straight edge, you must use some tool that itself has a straight or flat edge. You could create the edge of a wooden ruler, for example, but you would probably use a hand plane to do it. The base of the plane, which defines the straightness of the ruler edge, was in turn created by another, earlier tool with a straight or flat surface. If you knew the provenance of each tool in turn, you could find some very ancient tool from which modern tools descend.

I really loved the scoring on this one.

I actually liked the playfulness of the female voice while they were reciting the definitions. I think the point of those segments weren't to tell you exactly what the definition are but to give you an impression how technical and otherwordly they are. Compared to, say, the intuitive though imprecise measures of, say, a stone throw's away.

Those effects aren't just gimmicks. They serve a communication purpose. And this is why I love Radiolab.

For the setting the new standard for KG, how do they account for the differences in gravity depending on where you are in the world? http://curious.astro.cornell.edu/question.php?number=310

I love Radiolab.
Let me rephrase: I love the *content* I hear on Radiolab. But I have never in my life heard a more over-produced program. The random echoes for emphasis (that then loop underneath the actual VO for the next 10 or 15 seconds), the goofy sound effects, and — most irritating — the tendency they have for interjecting the sudden screech of an operatic alto at four times the decibels of the quiet talking that immediately preceded it! You should try listening to your own show on some earbuds, then decide if that's a pleasant experience.

I get it. You guys are cool, and edgy, and unique. Good. Fine. But can you just dial it down a couple of notches?

And why am I posting this comment on this particular episode? What set me off unfortunately happened at the opening of the program (which truly affected my ability to enjoy the rest of the show), when, as the standards for various weights and measures were being read aloud, the producers thought it might be awesome to have an excruciatingly annoying female munchkin voice at 2-times speed repeat it, about two beats behind the actual human voice. Holy cow, that was irritating!

Otherwise, fine work (truly)! Just please, a little less vigor from- and a little less caffeine for your audio production staff.

Has no one heard of a stone's throw away?
"Throw a rock"..?

What about using one mole of some element? If we found out that one mole of calcium was a kilogram, could we use that as a standard?

The reason why "The Mass of one Litre of Water at four degrees Celsius and one atmosphere of pressure" definition doesn't work is because it relies on a unit of pressure, the atmosphere, because the density, and therefore mass, of water changes with pressure. And because pressure is defined as force over area, and force as *mass* times acceleration, you would have a circular definition. And that just doesn't work.

Brad, I was confused about the definition too, because I also thought it was based on a given volume of water. Based on wikipedia http://en.wikipedia.org/wiki/Kilogram I think the initial definition was 1kg=the mass of one liter of water at 4 degrees C, but I'm assuming for ease of measurement, they made a metal one. And it so happened that the metal one was slightly off from the actual defined kg, but since that was the standard, then the definition of kg changed. I do wish they had clarified this point in the podcast, but still thoroughly enjoyed listening!

Minority Report

It will be better if this podcast is translated into alphabet or article ,too. Because I can't listen by android.

Thank you.

I was more distracted by trying to place the singing, from what movie was it taken?? I just cant place it.

I second the comment about the singing of the measurement definitions. As an ADD person, it was completely crazy-making.

In that same vein, your "mix tape" goodie is a nightmare for introverts, who are easily overwhelmed by too much simultaneous stimuli. This is one of those ideas that sounds better in your head.

Great story but the woman singing was really distracting, I get artistic liberty but I was really trying to hear and understand the definitions.

What where those podcasts mentioned during the direct donation portion of the podcast? I thought I heard "Byline Earned" and "Brainpickings", but I can't find anything called "Byline Earned".

-D

The elephant in the room here is why all the reverential worship in this American podcast of SI Units, when Americans stubbornly refuse to use SI units? Ditch your silly pounds, miles,inches and Fahrenheit and get with the 21st Century and the rest of the world community! Everyone else made the change - why not you?

Mass and weight are not the same thing. You use them interchangeably in the story which is quite disconcerting for a physicist. Other than that, great story.

1kg is supposed to be equal to the mass of 1L of water at 4 degrees C, right?

What am I missing?

One of my favorite family stories is of unconventional measurements - I was reminded of it by the description of throwing a stone to measure distance. In the 1950s my two great great aunts, who had spent their lives working as missionaries in China, moved to Taos, NM. The old woman who sold them land in the Taos canyon measured plots of land by how far she could walk before her cigarette burned down. A charming measurement that caused my dad headaches when he eventually inherited the land and had to determine propert lines.

A Kilogram isn't a measurement of weight, it's the measurement of mass. An object is the same number of kilograms that it is on the Moon as it is on the Earth, even though the attraction to the large body due to gravity is different. Different places on Earth will have very tiny variations on how much gravity is affecting that area verses others.

Does anyone know about Dinosaur Comics? 1. They're brilliant and 2. This very topic was covered (in much less detail, but in an amusing way nonetheless) on January 12, 2007: http://www.qwantz.com/index.php?comic=917

C0br4 from Honduras:

The music sounds to me like the Swingle Singers

http://en.wikipedia.org/wiki/The_Swingle_Singers

Not sure what song/s though. I have many of their albums on vinyl that I found at a thrift store and fell in love with! Check them out. Even if it's not them on the show you will very much enjoy them (especially the older works)!

Does anyone know the music used in this episode? I'm dying to hear it 500 times

The Veritasiun podcast is this same subject not long ago.

http://youtu.be/ZMByI4s-D-Y

So after listening for like 200 times I finally understood the name of the museum. Here's the link for everyone else interested

http://en.wikipedia.org/wiki/Musée_des_Arts_et_Métiers

Damnit somebody else beat me to it but yeah "World's Roundest Object" by Veritasium: https://www.youtube.com/watch?v=ZMByI4s-D-Y

PLs added other Payment options. Im from Germany and the most here dont have Creditcards. E.G. Paypal.

Greetings from Venezuela awesome people!!!
I've been a fan of you for a long time! But this is the first time that I'm compele to give an input;
I just want to point that you didn't talk about the other form to substitute the "Big K" and I don't know how you missed...
You can find on youtube an excellent video from "VERITASIUM" about (and you can search it by this title)
"WORLD'S ROUNDEST OBJECT"
I hope you can find it interesting as I do!
Love the show!

Donated! Always wanted to but forgot and finally got a new job so it's a lot easier to contribute to something I love so much~ Excited to also be receiving a mix tape

I have finally donated. I hope the mix tape uses music from the show. I have found so much great music listening to this show