The kilo is losing weight, changing all of science

The scientific community is working on the replacement:<p><i>Known as the Avogadro Project, the plan is to bring together enough atoms of one substance – silicon – to make a kilo.<p>Attention has focused on silicon because:<p>- its characteristics are very well understood<p>- a single crystal of the right size can be grown<p>- its atomic structure is extremely uniform<p>- its widespread use in the computer industry means it can be obtained with relative ease at high purity and resonable cost.<p>A spherical shape was chosen because a sphere has no edges that might get damaged and only one dimension has to be measured in order to calculate its volume.</i><p>---<p><a href="http://www.csiro.au/content/ps35k" rel="nofollow">http:&#x2F;&#x2F;www.csiro.au&#x2F;content&#x2F;ps35k</a><p><a href="http://www.youtube.com/watch?v=ZMByI4s-D-Y" rel="nofollow">http:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=ZMByI4s-D-Y</a>

Kinda off topic:<p>How is this good news for dieters? New kilo is lighter than old one, thus making all new measurements bigger in absolute numbers.<p>Besides, can&#x27;t they recreate a &quot;canonical kilo&quot; with the required measurements?

There is another competing proposal for solution that the article does not mention. It is define kilo as a specific number of Silicon-28 atoms, that have a well known mass. The laboratory with that proposal made the most perfect sphere ever, in attempt to allow measurements.

<i>&quot;Weirdly, it’s not even known if the IPK is getting lighter, or if the national prototypes are getting heavier — but either way, something is causing these kilos to change weight, by around 50 micrograms every 100 years.&quot;</i><p>Well they COULD always do that thing with the water where they heat it to 4 degrees celcius and measure its volume and weight. Then they&#x27;d know which it is.<p>That said, there&#x27;s a nice video on this: <a href="http://youtube.com/watch?v=ZMByI4s-D-Y" rel="nofollow">http:&#x2F;&#x2F;youtube.com&#x2F;watch?v=ZMByI4s-D-Y</a>

I often wonder why they don&#x27;t make a set of scales with a electro magnet at one end that attracts one end of a balance and you place the weight on the other end and adjust the strength of the magnet until you get a balance and from there can measure out that same weight. Now would need very well pression made electro magnet and balance.<p>Though idealy the ability to measure out a fixed amout of atoms of element and wheigh that and work out the relationship of how many atoms of element X is needed for a kilo. Well until then it is one of the last area&#x27;s of measurment that history still firmly has its teeth into.<p>Was nice TV show in the UK not long ago that covered the whole area of weights and measures from the science and history of them comming about. One of the better science shows.<p><a href="http://www.bbc.co.uk/programmes/b02xgf5d" rel="nofollow">http:&#x2F;&#x2F;www.bbc.co.uk&#x2F;programmes&#x2F;b02xgf5d</a><p><pre><code> &quot;Deep underground in a vault beneath Paris lives the most important lump of metal in the world - Le Grand K. Created in the 19th century, it&#x27;s the world&#x27;s master kilogramme, the weight on which every other weight is based. But there is a problem with Le Grand K - it is losing weight. Professor Marcus du Sautoy explores the history of this strange object and the astonishing modern day race to replace it.&quot;</code></pre>

I&#x27;m not a physicist, but it&#x27;s irritating to me that this article is using weight and mass interchangeably. I doubt they&#x27;d ever allow this, but the &quot;simple&quot; solution is to bring the weight aboard the ISS and capture its mass on an inertial balance.

Can somebody explain to me why an SI unit has the &quot;kilo&quot; prefix already in it, making other SI prefixes unusable with it?<p>1 kJ = 1000 standard units of energy.<p>1 kg = 1 unit of mass.<p>Was this just an unfortunate historical accident? But if the too that much care to make a unit system that makes intuitive sense, why would they let in such an annoying exception? Why didnt they just make &quot;gram&quot; the standard unit or just made up another name?

OK, here&#x27;s a wacky theory about why this is happening: The article says that the kilogram copies are brought to Paris to be compared. Therefore the copies are undergoing significant acceleration (e.g., transported on airplanes or trains) while the original in Paris remains stationary.<p>From the stationary kilogram&#x27;s point of view, all of the other kilograms had undergone relativistic mass increases during the time of their travel. Suppose a tiny amount of this mass increase is somehow actually retained when all the transported kilograms are brought to the same frame of reference (i.e., when the airplanes land in Paris).<p>What&#x27;s a simple way to disprove this idea?

I always thought 1 litre of water equals 1 kilogram. And as we know how long 1m is from nature, why don&#x27;t they use 10cm x 10cm x 10cm of water at a specified temperature as a prototype of kilogram?

The IPK being 2nd lightest out of 12 on the given graph is not statistically significant: even before accounting for post-hoc analysis.<p>The even distribution suggests (to my eye) that this is as likely random as by some systematic effect.

<i>90% platinum and 10% iridium for its virtual immunity to oxidization, and because it’s extremely hard-wearing</i><p>well thats bollocks. Platinum is hilariously soft.<p>There are a few issues, one is radioactivity. There are radioactive impurities that as they decay loose weight. Second, its postulated that there is a build up of trace amounts of mercury on the IPK due to environmental factors.<p>thirdly, they are not cleaned anymore. they used to be cleaned with shammy leather.

Wow, is it surprising to anyone else that a 1.54 inch tall&#x2F;wide cylinder of 90% Platinum &#x2F; 10% Iridium would weigh a kilo (2.2 pounds)?

Originally the meter was defined as the distance around the Earth, perpendicular to the equator, divided by 40 million. The French spent a while triangulating the French countryside from North to South to calculate the Earth&#x27;s curvature. Unfortunately it was assumed that the earth was a prolate spheroid, when actually it is oblate. This is one of the reasons it was reformulated. The East India Company triangulated most of the length of India, but it was tremendously expensive. <a href="http://en.wikipedia.org/wiki/Great_Trigonometric_Survey" rel="nofollow">http:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Great_Trigonometric_Survey</a>

It has always bugged me that scientists consider this obviously terrible kludge of a standardization method acceptable.<p>A civilizaton looking back 20,000 years from now and translating our scientific literature would be able to figure out what we meant by &quot;second&quot; by measuring the decay of a cesium 133 atom. But a kilogram (or any unit derived therefrom)? Sorry, the prototype is at the bottom of a crater. You can&#x27;t miss it - it&#x27;s the size of a whole golf ball, after all.

Could the fact that the other kilogram weights are being moved around maybe affect their weight?<p>Like they&#x27;re more exposed to chemical disturbance? Some form of tiny relativistic effect?

I&#x27;m not sure I understand: surely we can just say that one kilo is a certain number of carbon 12 atoms, and have done? Would seem sensible to me.

For anyone interested in the Planck and Avogadro projects to redefine the kilo, this video is an imperative watch: <a href="https://www.youtube.com/watch?v=ZMByI4s-D-Y" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=ZMByI4s-D-Y</a>

fascinating article, circa 2011.<p><a href="http://www.wired.com/magazine/2011/09/ff_kilogram/all/1" rel="nofollow">http:&#x2F;&#x2F;www.wired.com&#x2F;magazine&#x2F;2011&#x2F;09&#x2F;ff_kilogram&#x2F;all&#x2F;1</a>

If they made 40 copies of the prototype, they know exactly how to make it - don&#x27;t they? Why can&#x27;t they make one more?

We just need more mass surveillance on those kilograms... Kidding aside, can we please define the kilogram already?

Doesn&#x27;t 1cc of water (at 4C) == 1 gram? Why not use 1000cc of water as the measurement for the kilo?

&gt; This is a problem, because the weight of the IPK is the kilo.<p>A kilogram is not a unit of weight, but a unit of mass.

Since gold is allegedly the most inert element, why wasn&#x27;t the the prototype made of gold?

I&#x27;ve always wondered why the KG was not defined as a certain volume of Water at Sea Level.

Interesting, anybody knows something tath weights something similar to the variation registered at the standar kilo? Like a virus or so.. On a side note it must be a slow day to get this news at the middle of the front page with 3 votes in one hour..

no matter how much we think we know about the universe, we still don&#x27;t know sh#*!

The correct way to define a kilogram would be N number of molecules of Carbon (pick your favorite isotope) at relative speed = 0.

maybe it&#x27;s because the original kilo is a curiosity and therefore was passed through thousands of hands (maybe someone even dropped it?) the last 100 years?<p>this surely can have a &quot;losing weight&quot; effect.