Kilogram Gets a New Definition (bbc.com)

Scientists have changed the way the kilogram is defined. Currently, it is defined by the weight of a platinum-based ingot called "Le Grand K" which is locked away in a safe in Paris. On Friday, researchers meeting in Versailles voted to get rid of it in favour of defining a kilogram in terms of an electric current. From a report: The decision was made at the General Conference on Weights and Measures. But some scientists, such as Perdi Williams at the National Physical Laboratory in the UK, have expressed mixed feelings about the change. "I haven't been on this project for too long but I feel a weird attachment to the kilogram," she said. "I think it is such an exciting thing and this is a really big moment. So I'm a little bit sad about [the change]. But it is an important step forward and so the new system is going to work a lot better. It is also a really exciting time, and I can't wait for it to happen."

Le Grand K has been at the forefront of the international system of measuring weights since 1889. Several close replicas were made and distributed around the globe. But the master kilogram and its copies were seen to change -- ever so slightly -- as they deteriorated. In a world where accurate measurement is now critical in many areas, such as in drug development, nanotechnology and precision engineering -- those responsible for maintaining the international system had no option but to move beyond Le Grand K to a more robust definition.

Comments

excitement

[phik]

This is good, and very important. But exciting?

Re:excitement

[Anonymous Coward]

For a scientist who has been working with something that is over a century old, any change to that thing can be exciting.

Re: excitement

[Anonymous Coward]

UUGE!

Re:excitement

[sjbe]

This is good, and very important. But exciting?

To people who deal with precise measurements yes it is very exciting. Maybe not to you but certainly to some of us.

Re:excitement

[Anonymous Coward]

Most people find professional sports exciting. I find it boring as fuck. Go figure.

Re: excitement

[houghi]

For those in the field, yes. It is like sex, eciting for me, not so much for her. (At I hope it will be. First talk to a female human.)

Re:excitement

[orlanz]

Yes. Very much so. Even to those outside the field. To officially, precisely, and accurately say something is a "kilogram" our current method was well over a hundred years old and basically sneaker net.

You took a clone of the official standard and compared it against that. The clone couldn't be directly touched, couldn't overly jostled, had an expiration, sits in a double vacuum, and had to be physically moved in proximity to what was being measured or, more likely, calibrated.

With this method, you can build a simple machine (Kibble balance) [nearly] anywhere in the universe, calibrate it, find its measuring relationship to the universal constants, and you can figure out the "kilogram". THAT IS AWESOME.

Layman terms: Before, you had to say "I want this many rocks worth of your stuff." Followed by handing over the rocks. Now you can say "We both know what 1 and 3 are. I want 15 of what you got."

The measurement of how much of something you have, the kilogram, officially stands at the same level as the Meter, Second, and Temperature. All of which are based on universal constants and not the measurement of some useless fool's biology.

Re:excitement

[religionofpeas]

Also, very importantly, this method yields a constant reference. The old kilogram could be losing or gaining weight, and you wouldn't really be able to tell for sure.

Re:excitement

[Anonymous Coward]

Yes, I guess your idea of "exciting" is skydiving or some such, Fair enough,

Perhaps you have never been excited by an idea.

Which is quite sad.

Re:excitement

[Anrego]

Lets get full on pedantic.

I read your explanation and while I found it interesting, I did not however find it exciting. I suspect this reaction is probably common among most of the geek audience here.

A small subset of readers (and people within the general population) who deal with precise measurement and may be directly or indirectly effected by this may have become excited, but to most the reality that what we refer to as a kilogram is ultimately derived from a brick locked up in a vault somewhere in France is at most a neat bit of trivia.

This seems like a nice solution to a problem I was only mildly aware of and not at all concerned about, but exciting to most, nope.

All that said, who cares. Great bit of news and great article.

Re:excitement

[Anonymous Coward]

Rule 34 applies.

Re: excitement

[Anonymous Coward]

Except it's not constant because, right there in the equation, is the local gravitational gradient, 'g'. That varies from place to place based on elevation. And worse, it varies a whole boatload if you're in orbit or on the moon. Does anyone know if they are they getting around that problem somehow?

I prefer the pound

[Anonymous Coward]

It's 0.0714286 stones.

Re: I prefer the pound

[Anonymous Coward]

And € 1.13 at the moment.

Re:I prefer the pound

[MrMr]

No need to feel left out. The definition of the pound is also updated by this:
The international pound has been defined as exactly 0.45359237 kg.

Re:I prefer the pound

[idji]

Wrong, the pound was defined as that in 1959. nothing changed here

Re: I prefer the pound

[Anonymous Coward]

Runs in the family then, your mother also prefers a good pound.

Re: I prefer the pound

[Anonymous Coward]

Will there be commemorative t shirts?

Re:I prefer the pound

[pablo.cl]

I thought it was a joke.

Re: I prefer the pound

[Anonymous Coward]

They've redefined the kilo to be exactly 1/200th yo momma!

Re: I prefer the pound

[Anonymous Coward]

PoundMeToo

Re:I prefer the pound

[swillden]

Wrong, the pound was defined as that in 1959. nothing changed here

Since the pound is defined in terms of the kilogram, changing the definition of the kilogram implicitly changes the definition of the pound as well.

Re:I prefer the pound

[Anonymous Coward]

Yesterday: 1 lb = 0.45359237 kg = 0.45359237 (Le Grand K).

Tomorrow: 1 lb = 0.45359237 kg = 0.45359237 ("die kleine h").

So in that sense, the definition of a pound has indeed changed.

Re:I prefer the pound

[Anonymous Coward]

no. 1 lb always equals the same number of kilograms. If the kilogram changes the U.S. pound goes with it.

1 kg is always 2.20462234 lbs.

Re:I prefer the pound

[MrMr]

So did I.

Re:I prefer the pound

[MrMr]

Not really, that is only an approximation of the inverse definition. I you want to play that game you should write out 1/0.45359237 (which is exact)
Starts out like: 2.204622621848775807229738013450270338542070273360197835779292319224\ 8582135541653842193156820517064694...

Re:I prefer the pound

[Roger W Moore]

The international pound has been defined as exactly 0.45359237 kg.

That's interesting. Since the pound is a weight and the kilogram a mass unless they also fixed the gravitational field in that definition it's open to abuse.

Re:I prefer the pound

[Anonymous Coward]

WRONG!

U.S. Code, Title 15, Ch. 7, see. 272 clearly states it is 1 / 2.2062234

If you read Refinement for the Values of the Yard and the Pound from the National Bureau of Standards it mentions the following

The 1894 amendment, based on a recent determination of the British Imperial pound, gave the ratio as:

1 pound (avoirdupois) = 1 / 2.2062234 kilogram

which results in the approximate relation:
        1 pound (avoirdupois) = 0.453 592.4277 kilogram

Re:I prefer the pound

[NormalVisual]

Except that since the pound is defined as a fraction of a kilogram, it too is implicitly a measure of mass, not weight.

Re:I prefer the pound

[painandgreed]

The international pound has been defined as exactly 0.45359237 kg.

That's interesting. Since the pound is a weight and the kilogram a mass unless they also fixed the gravitational field in that definition it's open to abuse.

Just to make things even more complicated, the pound is used for both weight and mass.

Re:I prefer the pound

[Roger W Moore]

Please explain the ancient unit of pressure: pounds per square inch then. You cannot measure pressure in kilograms per square metre. This is why the old imperial unit system is utterly ludicrous. It is out of step with basic physics and lacks any coherent or even consistent definition.

Re:I prefer the pound

[NormalVisual]

PSI uses "pound" as a measure of force, where one pound-force is equal to the force exerted by one pound (mass) under the acceleration of 1g. One pound-force is what is meant when most people speak of "pounds", but in common usage the same is true of the kilogram - most people mean "kilogram-force" when they say "kilogram". The fact remains that "pound" is an SI-derived unit of mass, not weight.
 

Re:I prefer the pound

[suutar]

This. In theory the non-metric unit of mass is supposed to be the "slug" but pound gets overloaded just like kilogram does, to be both mass and force.

Re: I prefer the pound

[Anonymous Coward]

The kilogramme is not used as a force. The SI unit of force is the Newton.

Re: I prefer the pound

[Anonymous Coward]

Newton is a person. The unit is newton, with lowercase n.

Re: I prefer the pound

[suutar]

I know that and you know that but the people who make, e.g. bathroom scales are perfectly happy to report the force of weight in kilograms.

Re:Genius

[Anonymous Coward]

But then it wouldn't be new and "exciting"!

Ah yes a kilo will be the same worldwide.

[Anonymous Coward]

Drug dealers rejoice now that their calibration standard doesn't have to have traceability back to France..

Re:Ah yes a kilo will be the same worldwide.

[colinwb]

In the words of a stand-up comedian (alas I can't remember his name) who used to be a drug dealer: I prefer the term street pharmacutical representative!

Gravitational Field Varies

[rjune]

The strength of the earth's gravitational field varies. If you are using a Kibble balance to calibrate your weights, how do you compensate for that? Your kilogram mass will vary from location to location.
  Google: earth gravitational field
https://earthobservatory.nasa....

Re:Gravitational Field Varies

[Anonymous Coward]

This. It says the kibble balance must be calibrated with a kilogram. So how are they handling that then?

Re:Gravitational Field Varies

[thegarbz]

By it's very definition a balance in independent of gravity. The balance will remain the same and that 1Kg *of mass* will work just as well if you try this experiment on Jupiter.

Re:Gravitational Field Varies

[religionofpeas]

There are techniques to measure local gravity field without calibrated weights. For instance, you can measure the time it takes for an object to fall.

Re:Gravitational Field Varies

[religionofpeas]

In this case, the balance works by applying a magnetic field on one side, not a weight, so it's not independent of gravity.

Re:Gravitational Field Varies

[novakyu]

Yeah, they should have left out the Kibble balance part. That's more confusing than illuminating. In terms a layman can understand, kilogram is now defined the same way meter is: by defining a related physical constant to be an exact value.

Meter is defined today not by a physical object, but by defining speed of light to be exactly 299,792,458 m/s (that is, in significant figure terms, there are significant zeros following the decimal for-ever). With time defined by the atomic clock standard, this definition of speed of light also defines what a meter is (and many different experimental arrangements can be designed to use this relationship to actually calibrate real object).

With the vote today, kilogram is now defined by defining Planck's constant to be exactly 6.626070040 * 10^-34 kg*m^2/s (um, Wikipedia's not updated yet; the exact value they chose might be different from this number; important thing is that the value they chose now has infinite number of significant figures). Since meter and seconds are already defined, defining this constant defines the kilogram, and clever experimentalists can come up with better methods than Kibble balance for calibrating any local kilogram standards.

P.S. BTW, for scientists working in precision measurement area (the area NIST and NSF funds as they relate to fundamental science), this is an exciting news. It's a validation of accomplishments of their field, on the same (or possibly greater) magnitude was when atomic clock standard was adopted for the definition of second.

Re:Gravitational Field Varies

[93 Escort Wagon]

By it's very definition a balance in independent of gravity. The balance will remain the same and that 1Kg *of mass* will work just as well if you try this experiment on Jupiter.

Although if you’re attempting this on Jupiter, you’ll likely be distracted due to asphyxiation and crushing pressure - so work fast.

Re:Gravitational Field Varies

[idji]

You need to calibrate your Kibble Balance with an accelerometer which needs calibrating from your cesium clock and krypton-86 laser.
But the kilogram is now defined by the Ampere, which is defined as the current which creates a Force of 2×107 newtons per metre between wires 1 meter apart. but how do you measure a Force without knowing what a kilogram is?

Re:Gravitational Field Varies

[idji]

I suppose you could measure the force on a charged molecule of known mass...

Re:Gravitational Field Varies

[Fly Swatter]

infinite number of significant figures

First thanks for the explanation, but are you sure your meant 'infinite'?

Re:Gravitational Field Varies

[religionofpeas]

Or you could measure current by counting electrons.

https://www.nature.com/article...

Re:Gravitational Field Varies

[110010001000]

And what about manufacturing variances? Yeah, don't think about it too much. The new way is "quantitatively" better. If it wasn't, it would be a total waste of time and money.

Re:Gravitational Field Varies

[thegarbz]

so it's not independent of gravity

Magnetic fields have an effect on gravity so small as to not be relevant even at the precision we are talking about. This effect is relative to the existing gravitational field and above all ... kibble balance. Unless you make the balance 588 million km wide and have one side of it on Jupiter and the other side here on Earth, no the measurement is for all intents and purposes including those requiring the defining of an SI unit, independent of gravity.

Re:Gravitational Field Varies

[mrvan]

Not OP, but I'm pretty sure the answer is 'yes': the whole point is that it is not 299,792,458.00, or 299,792,458.000, but *exactly* 299,792,458, so with as many zeroes after it as you wish that are actually significant.

Re:Gravitational Field Varies

[swillden]

By it's very definition a balance in independent of gravity. The balance will remain the same and that 1Kg *of mass* will work just as well if you try this experiment on Jupiter.

But a Kibble Balance isn't that sort of a balance. It's a "single pan balance" which balances gravitational acceleration against acceleration caused by a magnetic field. So the Kibble Balance is very sensitive to changes in the gravitational field.

Luckily, it's possible to measure the local force of gravity with extreme precision, without reliance on the definition of the kilogram. It's done with dropping-mass gravimeters that measure the deflection of a laser beam, so it only relies on standard units of distance and time, and the speed of light as measured in terms of those units, not on the definition of mass. Obviously this is crucial or else you'd need a definition of a kilogram in order to calibrate your Kibble Balance.

So you can do this on Jupiter just fine, but you first have to measure the local gravitational field and adjust the amount of current you feed the Kibble Balance to balance against your kilogram test mass.

The biggest downside of this new method of defining the kilogram is that turning the definition into a measurement is incredibly precise and difficult work. It's so expensive to do correctly that for the foreseeable future there will probably only be a handful of wealthy countries who bother to do it. This means that for practical work, the definition will just be used to calibrate the exemplars that are used today, and everything else will continue as always. But it does mean that we now have a definition which is independent of those exemplars and guaranteed to be perfectly unchanging as long as the Planck constant remains constant.

Re:Gravitational Field Varies

[swillden]

infinite number of significant figures

First thanks for the explanation, but are you sure your meant 'infinite'?

Unlimited is probably a better word.

Re:Gravitational Field Varies

[religionofpeas]

That was not my point. My point was that it's a balance with a magnetic force on one side, and a weight on the other. One side is independent of the gravitational field, the other side isn't. In order to use the Kibble balance, you need to first measure local gravity and calibrate that.

Re:Gravitational Field Varies

[novakyu]

That's right.

P.S. Replying to say that Wikipedia did list the value of Planck's constant as newly defined: h = 6.62607015 * 10^-34 J*s. What's special about this value is that it's exact (note the lack of specification of experimental uncertainty), so if you were to write it as h = 6.626070150000000000000 * 10^-34 J*s, as annoying as that might be, you are not wrong (all those zeros—and more—are significant).

P.P.S. I guess they didn't update the table since the value is not effective until May.

Re: Gravitational Field Varies

[FuzzyDaddy2]

Tea you have to measure locally gravity to calibrate the kibble balance. Apparently that can be done to better than 1e-8 accuracy by measuring the acceleration of a free falling body.

Re: Gravitational Field Varies

[FuzzyDaddy2]

Damn autocorrect. Yes, not Tea.

Re:Gravitational Field Varies

[sc7007]

If the balance is anything other than a point, this is only true if you can find a place where the gradient of the gravity field is zero within the volume occupied by the experiment.

Re: Gravitational Field Varies

[Anonymous Coward]

Autocorrect appears to have dropped the 'quil' out of your first word, which I assume was intended to be 'Tequila.'

Re:Gravitational Field Varies

[thegarbz]

It's a "single pan balance" which balances gravitational acceleration against acceleration caused by a magnetic field.

Except it has a resting state where gravity acts on both sides of the balance which gives you effectively a calibrated zero independent of any gravity. Unless the gravity on one side of the balance is different from the gravity on the other side. ... And if that is an issue it would probably be a good idea to see if Gordon Freeman is standing behind you whacking things with crowbars.

Re:Gravitational Field Varies

[thegarbz]

Sorry disregard that, logic error, off for coffee.

Re:Gravitational Field Varies

[thegarbz]

Right I got you now.

Re:Gravitational Field Varies

[Roger W Moore]

First thanks for the explanation, but are you sure your meant 'infinite'?

Yes, it is a definition, not a measurement. Essentially we define the fundmental, unchanging constants of the universe as so many SI units and then use measurements to precisely define the individual units. In fact, in particle physics, we actually start by defining these fundamental constants as '1' unit each and then derive units for energy, momentum, mass etc. from them creating a system known as "natural units". It's not very practical for everyday quantities but very useful if you are dealing with fundamental physics.

Re: Gravitational Field Varies

[Fly Swatter]

How do they account for the movement of the moon? It effects the tides so I would think it is not insignificant. And the moon moves, when you weigh something the moon won't be where it was when you calibrated the scale.

Re: Gravitational Field Varies

[Anonymous Coward]

The amount of change in gravitational force over the period of time you're calibrating should not change in any appreciable way, given that you should not be taking longer than a few seconds to a few minutes to calibrate a scale and take a measurement. Even if it was an hour, the actual effect of gravity of a body of mass is inversely proportional to the square of the distance. It will be negligible for all intents and purposes, assuming reasonable significant figures are used.

Also, I hate to be nitpicky about this, but in a scientific discussion it warrants pointing out--it's "affects" the tides, not "effects" the tides.

Re: Gravitational Field Varies

[Anonymous Coward]

Almost no one uses that definition of the amp in practice. Resistance from the quantum hall effect and voltage from Jopsephon junctions gives you a very accurate setup smaller than a breadbox.

Re: Gravitational Field Varies

[Anonymous Coward]

Yeah fuck quantitative stuff, the new definition just doesn't feel right to people.

Re: Gravitational Field Varies

[Hognoxious]

Effect as a verb means cause. The primary cause of tides is the moon. The sun has some influence.

So, the moon effects tides. The sun affects them.

Re:Gravitational Field Varies

[Anonymous Coward]

the definition into a measurement is incredibly precise and difficult work

The official definition is as precise are required for the currently most advanced work. Feel free to use less precision, but you'll get.. wait for it.... less precision. Definitions will only ever get more precise. Not everyone needs it, but some do. The main point is the measurement is now reproducible by anyone anywhere at any time in the universe without access to any of the original equipment.

Re:Gravitational Field Varies

[Anonymous Coward]

If they can measure the gravitational constant so precisely, why don't they just measure the gravity exerted by whatever mass you are trying to measure?

drug development, nanotechnology

[religionofpeas]

How many times do you need a very precise absolute measurement in drug development or nanotech ?

Boy this guy's fast...

[SlithyMagister]

https://xkcd.com/2073/

Re:Boy this guy's fast...

[Actually, I do RTFA]

It's been in the news several times lately as its worked through the review process. I'm guessing Randall had the strip ready to go.

Defined as a unit of mass, not weight

[brendan.robert]

I know it's pedantic to have this discussion outside of a classroom environment, but Kilogram is a unit of mass and not a unit of weight. I suppose it was the electroshock therapy administered in science courses that makes it sound like fingernails on chalkboard to me when someone gets it incorrect in a publication.

Re:Defined as a unit of mass, not weight

[CustomSolvers2]

I know it's pedantic to have this discussion outside of a classroom environment, but Kilogram is a unit of mass and not a unit of weight.

I see your pedantry and raise you one "I guess that you meant force".

Re:Defined as a unit of mass, not weight

[CustomSolvers2]

Logically, the intention of my pun was "I guess that you meant force rather than weight". Because grams definitively measure mass.

Re:Defined as a unit of mass, not weight

[apoc.famine]

Unless you're measuring grams of water, then you're measuring volume.

Re:Defined as a unit of mass, not weight

[TeknoHog]

I know it's pendantic, but you can use a small object hanging from a string to measure the local ratio between mass and weight.

Re:Defined as a unit of mass, not weight

[CustomSolvers2]

Unless you're measuring grams of water, then you're measuring volume.

I am not sure whether I understand your statement. I guess that you mean some kind of commercial convention taking as reference X grams of water (under certain conditions) to determine volumes. I am not familiar with that. In any case, grams will always measure mass (although, informally, it is also common to use it for weight/force) and length^3 volume. On the other hand, there might be cross-references like what I was discussing in another sub-thread about determining force as a function of two currents separated some distance (force isn't part of current definition, but a current can be generated/provoke a force and that issue can be used to indirectly define force). So, your are probably referring to something like "volume of X grams of water", where that indirect reference might be used informally, but this doesn't mean that the volume is measured in grams or that you could use it directly for any kind of calculation (getting its length^3 equivalence is required).

Re:Defined as a unit of mass, not weight

[CustomSolvers2]

As far as this is a pedantic sub-thread, I will better replace my "length^3" reference with "volume unit". There are some cases like litres which don't match the length^3 format.

Question for better informed

[Anonymous Coward]

It's been long time since school, could someone help me? By new definition, kilogram is measured by measuring the current in electromagnet. But current definition of current (pun not intended) is defined trough force, and includes kilogram, A = kg*m/s^2. This looks like chicken and egg problem to me. Could someone enlighten me and explain how this is not recursive definition?

Re:Question for better informed

[CustomSolvers2]

But current definition of current (pun not intended) is defined trough force

This isn't true. Electric current is the flow of a electric charge and isn't composed by force or any other magnitude. The Ampere is one of the few SI units which isn't formed by other units. Force/energy is relevant to understand how a current is created, but it doesn't define its essence.

Re:Question for better informed

[Anonymous Coward]

Have you read the article you linked?

The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors a force equal to 2×107 newtons per metre of length.

One newton is the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force.

And now, kilogram is defined with current. So, could someone explain how this is not recursive definition?

Re:Question for better informed

[Anonymous Coward]

It's been long time since school, could someone help me? By new definition, kilogram is measured by measuring the current in electromagnet. But current definition of current (pun not intended) is defined trough force, and includes kilogram, A = kg*m/s^2. This looks like chicken and egg problem to me. Could someone enlighten me and explain how this is not recursive definition?

Please correct me if I'm wrong, but isn't current defined I Amps? And isn't 1 amp = 1 Coulomb of charge passing in 1 second? How's that based on the Kilogram?

A Coulomb is defined as the charge of a specific number of protons, again, not related to their mass.

I'm not seeing the issue.

Re:Question for better informed

[CustomSolvers2]

Have you read the article you linked?

No. But I don't need it to know what current is.

The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors a force equal to 2×107 newtons per metre of length.

This is pretty much what I explained in my previous post: force (or energy, formed by force) is required to produce an electric current. Or, in other words, an electric current is in a position to generate force/energy. But all this is different to its essence: a flow of electric charges what, from the physics point of view, is considered as an indivisible whole. Pretty much the same than the pair mass and force. A massive object is able to generate force/energy, but it doesn't mean that force is part of its definition.

SI units and Wikipedia are pretty useful on this front, for example, visit the page for force (newton) and see under "SI base units" its components. For Ampere you don't see anything because it is already a base unit, exactly the same than grams or time.

Re:Question for better informed

[CustomSolvers2]

Also bear in mind that physics (and science in general) isn't exactly a perfectly well-planned system which was built one day by carefully thinking about how to do everything perfectly. There are even different fields facing pretty much the same reality from different points of view (e.g., chemistry and physics). Within physics, there are different approaches which, although having a somehow coherent behaviour, can't be precisely used unrestrictedly. For example, electric current (and other electric magnitudes) have their specific treatment, not exactly 100% compatible with mechanical ones. Although the idea force as accelerated mass certainly holds everywhere, the electrical calculations aren't performed in the same way than the mechanical ones. You don't care about f=m*a when dealing with electrical currents, but about concepts like resistance, voltage, etc. which output things like energy which you use to link to other types of calculations like mechanical force.

Re:Question for better informed

[CustomSolvers2]

Pretty much the same than the pair mass and force.

I think that the velocity-energy/momentum analogy is more descriptive. You know that having a moving object is associated with energy/momentum, but it doesn't define it essence. Its essence is defined by velocity (certainly started by energy/momentum, but not defined by it) and, together with something else (= mass), it will output energy/momentum.

Re:Question for better informed

[Anonymous Coward]

I lost you... In the meantime, I found the answer to my first question.

If anyone is still interested, not only kilogram will be redefined. New definition of ampere will not use force as current, but elementary charge. I always wondered why wasn't it always like that.

Re:Question for better informed

[CustomSolvers2]

I lost you... In the meantime, I found the answer to my first question.

If anyone is still interested, not only kilogram will be redefined. New definition of ampere will not use force as current, but elementary charge. I always wondered why wasn't it always like that.

You lost me? You found the answer? LOL. Haven't you seriously understood what I have explained you various times and with various additional references?!! Seriously and by being as respectful as I can under these conditions: this (physics or properly understanding/learning slightly complex concepts) doesn't seem your calling, better focus on whatever you are doing and let all this for other people. Anyway, I will better write some clarifications about the rest of your post because some people might read it and well... pure ignorance isn't precisely what the world needs.

New definition of ampere will not use force as current, but elementary charge

Before answering that, I will clarify something that perhaps isn't too clear for everyone. The current redefinition of the kilogram or of whatever other physical magnitude doesn't affect its essence/theory at all. This is just about updating the used-so-far numerical convention mostly relevant for conversions between different systems (even though, practically speaking, there shouldn't be any noticeable difference). For example, converting kilograms to pounds or knowing the kilogram equivalence of a bag of potatoes. F=m*a will always be like this. Exactly the same than amperes being the unit of electric current and not being defined by force.

What this anonymous, not-accepting-the-limitations-of-his-knowledge, not-willing-to-learn and sharing-pure-ignorance individual is saying makes clearly no sense. The electrical current reality/theory/coordination-with-other-units has always been exactly the same than today (I mean... theories can be changed/updated, but the most basic ideas have remained pretty unaltered since long time ago and most of modifications have consisted in adding new contexts/theories or tuning up some calculations). A different issue which I didn't comment before and which is relevant to clarify the aforementioned nonsense is that there are units below the current/ampere, but its usage depends on the given context/system. As said, for SI and its associated electrical calculations, you usually rely on amperes which is assumed to be a base unit, meaning that it isn't formed by anything else. But this is just a (calculating) convention for that given context/physics-subsystem and it doesn't oppose to the fact that current is formed by charges (whose unit is effectively the coulomb, not considered part of amperes by SI though as a way to keep coherence with other units and because of simply reaching the boundary of its scope, as explained below) or many other aspects at an even lower level (subatomic analysis taken care of by different theories, approaches, units). The idea is that if you perform macro-calculations and you rely on certain context (mechanics or electricity or thermodynamics or any other one) you would use certain units, conventions, systems, not necessarily identical or directly compatible with the ones of different approaches although theoretically coherent with all them. An example is my previous reference to f=m*a, rarely used for electrical calculations, but whose underlying idea (accelerated mass provoking a force) is expected to hold everywhere.

So, electrical current isn't defined by force (not now, not ever), but force might be indirectly defined by electrical current (+ something else). Exactly the same than mass isn't defined by force, but force might be defined by mass (+ something else). Exactly the same than velocity isn't defined by momentum, but momentum might be defined by velocity (+ something else). Another very important idea to bear in mind when dealing with fields helping to understand reality at any level (e.g., any branch of physics or chemistry) is that, although

Re:Question for better informed

[CustomSolvers2]

It is kind of hard, but I have to recognise that I didn't understand your point properly until after having written my last post. I realise now about my error. I apologise about it. Even though you definitively failed to understand my point, I also failed to understand yours and both errors seem equally bad. I was referring to units/calculations and you were referring to abstract-definition coherence. And you are right, the ampere is being redefined as a way to keep the new system consistent. In any case and to make sure that my point is clear: this has no effect whatsoever in either currents/forces and their respective relationships. They will always be independent entities and, in case of wanting to see any kind of relationship, it would be the definition of force depending on current (or many other things) and not the other way around. Or, in other words, current is assumed to be there, force is assumed to be provoked by something.

The most ironic part is that I found pretty amusing your reference to school physics, but actually I do recall that concept of current being defined as a function of force only at school. This has no logical, calculation sense, just an arbitrary (practical) one. So, I have used/worked on/performed lots of calculations about physics without ever finding that idea again. From a theoretical perspective, it does make sense to define everything from the same basic unit (kilograms) and the easiest way to get to current from mass is logically via force. Never thought about it and yesterday didn't do even a basic research because of being sure about my units/calculations-based understanding.

Anyway, sorry about having been a bit too obtuse. On the bright side, I have thought about/shared quite a few ideas which you or other people might find helpful. And even highlighted a curious irony: until this point, the unit of electric current was theoretical defined as a function of the unit of force, something which theoretically doesn't form part of its constituent elements. I guess that it is a quite descriptive sample of one of the points which I tried to make in one of my other posts: the building of physics/science is very far away from being completely coherent, a reality which is rarely understood by almost anyone regardless their knowledge.

Re:Question for better informed

[CustomSolvers2]

Although most of the ideas in this post are correct, it still denotes my misunderstanding of the original intention of the question. I have written a clarification (+ an apology) in another post below.

Re:Question for better informed

[CustomSolvers2]

After re-reading my posts, I have to further apologise because of my behaviour in general. I didn't understand your point, didn't read your comments properly, didn't care much (not even doing a basic research, reading what I was linking!!), reacted in unnecessarily aggressive ways and wasn't even able to keep the discussion reasonably simple/focused what is particularly important when dealing with so complex issues. This is even more reprehensible by bearing in mind that I was the one spontaneously answering to your question. I am really sorry. The reasons/excuses? Being a bit too tired and some other issues (some nonsensically weird interactions with pretty ignorant and aggressive individuals here lately), but then why posting at all? Actually, my usual reaction when seeing certain behaviours in a website is simply stop using it, at least, temporarily. Completely my fault and sorry again. In any case, I think that I have shared quite a few worthy ideas which hopefully will be useful for someone.

Re:Question for better informed

[CustomSolvers2]

After all my previous posts which I would delete if I could (unnecessarily confusing), here you have the answer which I should have written since the very first moment. Electric current isn't defined by force. It is either a base unit (no constituents) or a flow of charged particles. For all the intend and purposes, electrical current and its SI unit, Ampere, can be considered at the same level than time or grams (eventually, forming other units but not being formed by anything else other than themselves). A different story is the theoretical definition of the electrical current unit, Ampere in this case.

The SI units are meant to be somehow synchronised with the underlying physical relationships. For example, force equals mass*acceleration and, consequently, N (force unit) equals kg (mass unit) * m/s^2 (acceleration unit). Note that this doesn't happen in other systems of units like Imperial. By putting these ideas together with the basic requirement of setting up a reliable reference system for each unit (1 kg is the basic mass unit, excellent! But how much is this in pounds, potatoes, whatever?), it doesn't seem too difficult to understand that the reference systems (scales, ways to compare them with other units referring to the same magnitudes) of SI units are defined as a function of each other. As far as the basic reference system for SI/metric has traditionally been the kilogram, it does make sense that all the other units were defined as a function of it.

When performing calculations, you can easily do f=m*a or m=f/a or a=f/m and, mathematically/calculation-wise, these three approaches might be considered equally good. If now we look at the physics concepts underlying these formulae, things would be different. For physics (from a microscopical, mechanics, calculations point of view), mass is assumed to be a base unit, an absolute minimum in that context, it only depends on itself. Its value might certainly be determined in quite a few scenarios by relying on calculations like the aforementioned ones. But these indirect ways to determine the mass value in certain scenario can't be confused with these conditions being essentially required to define mass. Force in its simplest form requires, at least, a mass and an acceleration to be defined. Similar ideas are applicable to acceleration. So, from a physics, SI point of view (in this macroscopic context/calculations) mass could only be coherently defined by itself. On the other hand, from a mathematical point of view it could be defined in many different ways (e.g., m=f/a) and, from a system-of-reference/pragmatic point of view, in many other ones (e.g., the current new system where 1 kg isn't the basic reference anymore or any other approach like defining mas as a function of certain volume, force, acceleration, etc.).

If you apply the aforementioned ideas to electric current/amperes (known to be formed by other elements, but assumed to be indivisible in this specific context), you would understand that current doesn't not depend on force. It doesn't happen in its SI/ampere/treated-as-a-whole version or in any other one (e.g., flow of charged particles, coulombs). Rather than mass, you could think of velocity and its relationship with momentum/energy. The energy/momentum definition does depend on a moving object/velocity/acceleration. Analysing a moving object doesn't require caring about the originating energy/momentum, it only depends on its own (space traveled by unit of time). The definition of amperes (not electric current) did actually depend on a unit of force, but only for pragmatic reasons. From the physics point of view, electric current has always and will always continue depending on itself (+ constituent elements which might be considered depending on the given context/branch but none of them being force). Without denying the importance of the changes in the SI systems of reference, they will have no impact on theoretical physics. The will also have no noticeable impact on practical physics as far as the conversion factors will r

Re:Question for better informed

[Anonymous Coward]

They're not truly circular definitions. For example. Lets define a meter as speed of light for 1/k seconds or m = c * s / k

You start off with m = c * s / k But then they decide to improve the precision of a second
s` = m / (c / k)
Now we have a higher precision s

Now lets increase the precision of m with the higher precision s'
m' = c * s' / k

Now lets increase the precision of k
k' = c * s' / m'

Now lets increase the precision of c
c' = m' / (s' / k')

Now lets further increase the prevision of m
m'' = c' * s' / k'

Rinse and repeat where each time you use better tooling and methods to increase the precision while staying within the margin of error or the prior methodology of measurement. Please ignore any stupid math mistakes I probably made. While the end result is arbitrary, the main benefit is it's backwards compatible, while increasing precision along the way.

Re:Question for better informed

[Anonymous Coward]

And now, kilogram is defined with current. So, could someone explain how this is not recursive definition?

Along with the kilogram, the ampere (and the kelvin and mole) got redefined:

The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602176634×1019 when expressed in the unit C, which is equal to A s, where the second is defined in terms of Delta nu_Cs.

So the ampere now only depends on the constant e and the definition of the second.

Re:Question for better informed

[CustomSolvers2]

Even in this last version, some ideas weren't completely clear. By assuming that it is already clear the difference between physics/magnitudes/force-current (the main, ruling, unmodifiable part) and system-of-units-and-its-improvements (the instrumental, fully-conditioned-by-physics, currently-updated part), it is certainly desirable to keep some coherence. It is possible to divide it into internal (physics/SI with respect to themselves) and external (SI with respect to physics) coherence. As explained in some of my previous posts, I have realised during this discussion that, until this moment, the external coherence wasn't exactly respected at least in the force-current front (SI defining current from force and physics doing it the other way around). And the new SI version is fixing this issue because of making everything depend on what, according to physics, is the real base for everything: atomic-level interactions (logically, only up to certain "depth"). From that, it is certainly possible to build a coherent-with-physics definition of the current/mass/force units.

A different story is the internal coherence of SI. When you set up an inter-connected system of whatever, all the definitions have to make sense with respect to each other. For example and by bringing computer ideas, trying to avoid circular references. There doesn't even need to be truly speaking, unavoidable circular references where the definition of certain item is definitively impossible. For a good enough system, there shouldn't be even apparent, theoretical or conceptual inconsistencies. I understand (since yesterday in my last posts :)) that your original question was meant to account for (what you thought that was) an issue here. You pointed out that the modification of the ampere definition was the solution which you were looking for, the solution of the circular reference which you thought that the new definition of kg provoked in amperes (via newtons). This redefinition is certainly a pretty sensible consequence of having moved from a macroscopic arbitrary fundamental unit (kg) to the microscopic level (what would have been the point of keeping the old kg-based definitions when the kg isn't the central part anymore?); basically, it is a sensible approach to keep internal coherence within the SI. It is also a way to fix that external incoherence with respect to physics (current shouldn't depend on force).

Despite the previous paragraph and theoretically speaking, it could definitively be possible to include the new definition of kg (and, consequently, newton) together with the previous definition of ampere: amperes would be defined by newtons/metres, defined by kgs as so far (previously defined by itself, now at the particle level). Amperes would be indirectly defined as so far via a magnitude (mass) whose definition has been updated and is now more accurate. I don't see any chicken-egg scenario or logical inconsistency. I do see an external incoherence with physics because of inverting the logical force-depends-on-current-not-the-contrary; and an internal incoherence because of not applying the new basic ideas to the definition of amperes. In any case, I think that all this is tremendously unimportant in comparison with not having clear the main ideas here, namely: differences between physics/SI, magnitudes-&-the-reality-they-model/units-maths, theory-calculations/instrumental-resources.

Re:Question for better informed

[CustomSolvers2]

I don't see any chicken-egg

I guess that your "kilogram is measured by measuring the current in electromagnet" refers to the way in which the Kibble balance (supposed to be measuring kgs by applying the new definition) works. Firstly, the main idea is relating atomic-level definition (via Planck constant) to kilograms, the measuring methodology/machine is irrelevant from the point of view of the unit. Exactly the same than balances were supposed to be used to compare the previous kilogram version with other objects but the exact way in which they worked was irrelevant for that old definition (any balance weighting in any accurate enough way should be fine).

Secondly and even in case of really caring about the way in which the Kibble balance (or any other approach) works, currents measured in amperes could be used there without any problem. As it should hopefully already be completely clear, one thing is the physics/reality-it-models-via-instruments-like-units and a different story is the internal definition of one of the systems on which it relies. Electric currents and amperes are completely independent on force/mass and that's why they can form part of a formula defining it. The only real utility of the old/new definition of amperes (other than being parts of a system meant to be coherent, reliable, consistent, etc.) are scenarios where you want to compare that unit against ones in other systems. From the internal, SI-based calculations point of view, amperes, kgs, newtons, everything is self-defined. All the units are assumed to mean something, but that exact meaning (what the old/new definition actually does) is irrelevant within the given calculations (1 ampere is/was/will always be 1 ampere; the current definition of ampere is relevant to know the equivalence of amperes with units from other systems, but this would be unit conversion not physics calculations).

Long story short, there wouldn't even be any real problem with keeping the old definition of amperes with the new definition of kilograms. There would certainly be some external/internal inconsistencies and it wouldn't really make too much sense to do that for various reasons. But it wouldn't really be an egg-chicken, circular-reference kind of problem. It might look like this being the case for someone not understanding the situation properly. But this is the problem with not understanding something properly: you might see what isn't really there :)

Re:Question for better informed

[CustomSolvers2]

This post with my sincere apology is modded up. It's OK. I have even do things on these lines myself in the past. But then I write a proper answer (+ 2 extensions today) which might be probably ignored. And well... I do think that this is by far much more important than the apology. I guess that finding surprising/highlighting-worthy when someone apologises is unfortunately kind of normal in internet nowadays. Personally, I don't see it as a big deal because I do always apologise and try to correct my mistakes as soon as I am aware of them. I also expect the same from everyone else, even though rarely find it. Anyway, this seems like a good last post before making a pause here. I like Slashdot and will continue reading it regularly. I like most of the community here and their usual concerns (= technical stuff and properly understanding). But here and there, I get a bit tired of tolerating the kind of random stupidity that, unfortunately, is present everywhere and mainly in internet. So, I will better focus on reading/modding for a while.

Re:Question for better informed

[CustomSolvers2]

Unfortunately, I think that I have to make one last clarification. I apologised (twice) because I am rarely in the situation of not properly understanding others (at least, their words within the right context) and did feel bad about it. It is a quite common scenario in internet or here though. Just take look at quite a few of my last posts and at me systematically correcting random misinterpretations (and nobody apologising). As it should already be clear to anyone reading the aforementioned proper answer & extensions, I consider my mistake of not looking up the old SI definition of amperes pretty irrelevant (a bit disrespectful towards that AC though). Basic SI/other system definitions are certainly nice-to-have bits of information, although mostly under very specific conditions (e.g., at school or when writing an article about the given unit). I will never complain about improving my knowledge, but this isn't particularly important for almost any physics/engineering understanding/usage. On the other hand, thinking that electric current does (or did) really depend on force and/or not understanding the difference between physical phenomenon, theoretical definition of a unit and calculations used in a comparison methodology do seem pretty serious misconceptions. The fact of thinking that this new over-clarification, further-summary, still-simpler-and-more-to-the-point post is really required should be understood as the main reason why I will not be posting much here and in general for a while: nobody seems to be able/willing to adequately understand almost anything (+ they rarely apologise).

long hand of liberals

[Anonymous Coward]

This is the long hand of insane liberalism at work. Soon these "scientists" will going to try again for impose there flawed "metric" system on us.

Re:long hand of liberals

[Fly Swatter]

The current pound is based on the kilogram, so we all suffer the same flaw haha.

Re: long hand of liberals

[Anonymous Coward]

No, the pound system is based on the 25 pound weights I use at work to calibrate new scales right before I put the serial number sticker on.

Re:Genius

[thegarbz]

I'm amazed at your constant ability to out-think all of our scientists. Your value is wasted as a Slashdot troll. If only they'd have seen you for your genius we'd have cured cancer by now.

Are all electromagnets equal?

[Fly Swatter]

Do they have a guaranteed efficiency vs electric input? Or does this not somehow apply?

Doesn't each kibble scale require calibration whenever the altitude changes? What do they use as a reference for calibration since it appears even the Kg reference is not stable?

- Yep I got plenty of dumb questions.

Re:Are all electromagnets equal?

[hackertourist]

Don't be an idiot. This is the result of 20 years of work, a vast amount of actual data underlies the decision taken today.

Re:Are all electromagnets equal?

[complete loony]

The Kibble balance uses measurements of voltage, current, velocity and gravitational acceleration in order to calculate the mass that was placed on the balance. Here's the maths involved.

Then it's likely that those measured masses will be used to calibrate other equipment, as is done now with reference masses that were compared to Big K.

A thought experiment, Hydrogen

[Anonymous Coward]

Do we need mass? I'm at atom level with nothing but electric force.

Here is a proton, neutron, and explanation of how they formed, and why they are stable.
An explanation of a hydrogen atom. Next up, why we're a matter universe, and an attempt to pick apart the standard model.

If you've missed any, please step back and read the earlier ones first.

Postulate A: Mass isn't real
Postulate B: the energy in light is also 'kinetic'
Postulate C: Light bind force must be cyclical
Postulate D: only 2 fundamental particles are possible
Postulate E: the only force is electric
Postulate E2: The binding force (Postulate C) is electric
POSTULATE F: The speed of light is obvious
POSTULATE G: Time is measured in spins
POSTULATE H: All dipoles are equal, matter,even red and blue light
Postulate I1: Donut Particles
Postulate I2: Donut Particles are themselves dipoles
Postulate I3: Anti-particles
Postulate I4: Bigger particles twist and break
Postulate J0: How light binds to matter
Postulate J1: A Slit is a phase sorter
Postulate J2: Gravitational lensing is just diffraction
Postulate J3: Electron is a Donut Sandwich
Postulate J4: Binding force is harmonic electric
Postulate J5: Photons from Electrons
Postulate K: How fast do forces propagate?
Postulate L: Warp, Time Machine, Light squared computers
Postulate M: The Hydrogen Atom
Postulate M4: 50% matter 50% anti-matter

Postulate M: Hydrogen Atom

An 'energetic' electron must be the -ve monopole wrapped in an {F2 Donut}{-v2 monopole}{f2 Anti-donut} from Postulate J3. This has the H2 binding wrapper needed to attach to a H2 nucleus slot which is how its binds. (Postulate J4). This F2 donut is what carries the energy.

A non-energetic electron is just the -ve monopole. It only binds (moves) via H0 forces, higher harmonics can only oscillate it.

Since F2 is the only 2 axis symmetric particle (Postulate I4), the +ve version of that, {F2 Donut}{+ve monopole}{f2 Anti-donut} must be at the center of a proton too.

i.e. a positron is at the center of a proton.

And for the positron not to cancel the electron requires another wrapper around the nucleus. To displace electrons one way, and positrons another way so they cannot overlap and cancel. And for the balancing forces that wrapper needs to be another particle/ anti-particle pair.

So we can speculate what a nucleus might look like.

-----
Postulate M1: Hydrogen, Proton / Atom

The nucleus of hydrogen (a proton) must be wrapped positron.

Proton Axis Y: {f1 donut}{xxxxxxxxxxxx}{f1 anti-donut}
Proton Axis X: {f2 donut}{+ve monopoleX}{f2 anti-donut}
Proton Axis Z: {f1 donut}{xxxxxxxxxxxx}{f1 anti-donut}

Think of the positron standing upright wearing a belt, on the sides of the belt... a f1/anti-f1 donut. Likewise front and back, another pair of F1/anti-F1's.

Looking from the top down: ............{f1 donut}
{f1 donut}{positron}{f1 anti-donut} ..........{f1 anti-donut}

This pushes the positron up and to the left, and when an electron is added, the electron is pushed down and to the right. Note: THE ELECTRON SLOT IS INSIDE THE PROTON. You often think of electrons as circling outside, but it's as close to the center of the nucleus as the positron! This electron is *inside* the proton.

Each of these charged particles is being spun around in 3 axis, so they trace out spheres, separate but in unison. If you measure this by charge, you will think the proton is a sphere of +ve charge, and a hydrogen atom, is an hour-glass shape of +ve and-ve sides, but this is not correct, the +ve and -ve monopoles trace out partially overlapping spheres, you are measuring the net charge of those spheres.

The lowest energy particle possible is the F1. So the wrapper used to keep the electron/positron separate is an F1 donut and anti-donut. The F1 will couple with its anti-donut is why they stick together. The positron in the center is what stops them coll

Re: Genius

[Anonymous Coward]

The reasons changed like this have been talked about for a long time but only just now changed, is researchers spent a long quantifying exactly what the accuracy of the new method is and how it changed with time.

A lot of people wanted mass to be defined as a fixed number of atoms. Efforts to make test masses from scratch showed that the variation was larger than the le grand K approach, so that didn't get used.

Even though the Kibble balance requires a measurement of local gravity, the accuracy and drift with time have been shown to be an order of magnitude smaller than the prototype based approach. So from an accuracy perspective, yes, it has been quantitatively demonstrated to be better. The only complaint is how expensive it is, so likely only the larger national standard institutes will be able to maintain one.

So no, just because no measurement is perfect does not mean all measurements are equally bad. The reason the BIPM and CGPM take their time is to actually measure these things, to be sure new definitions are more repeatable.

Planck's constant redefined

[sjbe]

Basically what they did was they defined Planck's constant to be a fixed value pretty close the the calculated number previously used. So instead of calculating Planck's constant from an arbitrarily defined kilogram they define the kilogram (and a few other constants) from an arbitrarily defined Planck's constant. This takes the error bars away from Planck's constant and the other fundamental measurements fall out naturally as a result to precisely defined and fixed numbers.

Within a drop Weight of 1 Liter of Water?

[BrendaEM]

Please don't make the metric system stop making sense. We already have a nonsensical measuring system, here in the U.S. .

Re:Within a drop Weight of 1 Liter of Water?

[jfdavis668]

Why not make is a cubic Smoot of water?

Yes genius

[sjbe]

Any individual Kibble balance will also deteriorate and be out of range of the others. There will also be differences in construction since no system is perfect. You might as well use the current method.

I have a hard time telling if you are a troll or just ignorant. What they did was they redefined Planck's constant to be a fixed number. So instead of measuring Planck's constant from an arbitrarily chosen value for the kilogram they measure the kilogram from an (sort of) arbitrarily chosen Planck's constant.

Re:Yes genius

[110010001000]

I know exactly what they did. But apparently you don't, based on your "explanation".

Re: Yes genius

[Anonymous Coward]

Nope, the person you are responding to knows exactly what they did. Planck's contact is now a defined value, like the speed of light. This is already often done in some fields where c and hbar are just set to one.

The Kibble balance is just the method du jour of implementing that definition. But with a physics based definition, people are free to use any other measurement method that connects to Planck's constant and mass.

Re: Genius

[110010001000]

Sure. Like I said, genius.

Veritasium

[SCVonSteroids]

Our friend at Veritasium does an excellent job breaking this down:
https://www.youtube.com/watch?...

Re:Veritasium

[jfdavis668]

I'm upset that they redefined the Ampere.

Mass vs force

[Anonymous Coward]

Wait, I thought that grams were a measurement of mass, not a measurement of force? Are they changing this? Because it was my understanding that a gram is a gram is a gram on Earth, on the moon, in space, etc. The is in contrast to a pound, which is a measurement of force applied to mass from gravity, where it would be different in each of the mentioned places. They now want to measure grams using gravitational force here on Earth? I can see this leading to all sorts of problems.

Re:Genius

[110010001000]

I understand: newer is always better. After all, your first computer had only 1 MB of memory. I've always thought the big problem with the world was that we had too simple a system to measure a kilogram. Why not replace the hunk of metal with a complicated balance that only a few standard bodies can afford to make and maintain? It is accurate to 0.000001%, unlike the old method, which was 0.000005%. Total genius. Plus you get to have a party for the scientists, so it is all good!

Thought Experiment: Leptons, Quarks

[Anonymous Coward]

Looking at the standard model, head scratching.

If you've missed any, please step back and read the earlier ones first.

Postulate A: Mass isn't real
Postulate B: the energy in light is also 'kinetic'
Postulate C: Light bind force must be cyclical
Postulate D: only 2 fundamental particles are possible
Postulate E: the only force is electric
Postulate E2: The binding force (Postulate C) is electric
POSTULATE F: The speed of light is obvious
POSTULATE G: Time is measured in spins
POSTULATE H: All dipoles are equal, matter,even red and blue light
Postulate I1: Donut Particles
Postulate I2: Donut Particles are themselves dipoles
Postulate I3: Anti-particles
Postulate I4: Bigger particles twist and break
Postulate J0: How light binds to matter
Postulate J1: A Slit is a phase sorter
Postulate J2: Gravitational lensing is just diffraction
Postulate J3: Electron is a Donut Sandwich
Postulate J4: Binding force is harmonic electric
Postulate J5: Photons from Electrons
Postulate K: How fast do forces propagate?
Postulate L: Warp, Time Machine, Light squared computers
Postulate M: The Hydrogen Atom
Postulate M4: 50% matter 50% anti-matter
Postulate M5: Found your Quarks, Leptons, etc. sortof

---------------------

Postulate M5: Quarks, Leptons, Mysterons etc.

Lets go look for your quarks, leptons etc.. honestly since a lot of the theory here assumes mass, and worse, its mass measured as millions of electron volts... I have no idea how to sift through the this. wikipedia...

Please note:
An F3 donut, is twisted as {2+1} which means it has a counter spinning portion. So classifying particles by their H2 spin would see this as two particles (or worse, the twist is not perfect, if they were perfect the donut would break, so part of each donut is also in the twist, you may be classifying twisted partial donuts by some partial spin).

[POSTULATEM5_ANTI] A donut/Anti-donut wrapper, has the same H2 spin, but counter H1 spins. I suspect you cannot separate the donut from the anti-donut, because of the H2 spin. Which implies your 'spin' is H2.

If a monopole is next to a dipole or donut, it oscillates. Postulate J4. If the particle had mass you would estimate energy from that oscillation, missing momentum, but in the dipole model the only energy is kinetic/potential over the electric field. If the field is oscillation (i.e. a nearby dipole) and the monopole is tracking the underlying field, then the wobble does no work. It's simply following the underlying field!

No need for insane fixups, if there is no mass. Postulate A, explains why there is no mass.

-----

Lepton:

I think that a monopole = (charged lepton) and a dipole = (neutrino)

The does not undergo strong interactions' implies H1 not H2 (dipole not donut).

I think the dipole is your neutrino. 'Momentum' is phase in the dipole model and needs spin (from your beta decay example). So it cannot be a massless monopole. Which means it would have to be spinning... another pointer to the dipole. H1 not H0.

Faster-than-light lepton? Yep, a dipole with a phase component in the axis of travel.... since it spins at F, technically it is travelling faster than light during half that spin.

Likewise if you measure a dipole from a particular interaction, it will have an orientation relative to something. But that's not a special property. You can flip a dipole by inducing a phase component to flip it over very easily. All those leptons classified by spin, are clearly dipoles.

Here are the dipoles and monopoles.

-----

Quarks

Oh boy, I don't know what to do here. You have a particle based on spin, probably H2 spin (from POSTULATEM5_ANTI)? Which suggests they are donuts.

Guess:
F1 = up quark
F2 = down quark
F3 = part 1 Up + part 1 down quark.

Looking at the proton:
Proton Axis Y: {f1 donut}{xxxxxxxxxxxx}{f1 anti-donut}
Proton Axis X: {f2 donut}{+ve monopoleX}{f2 anti-donut}
Proton Axis Z:

If you're trying this on Jupiter

[Anonymous Coward]

Although if you’re attempting this on Jupiter, you’ll likely be distracted due to asphyxiation and crushing pressure - so work fast.

I sense you have experience in avoiding IRB protocols and would like to subscribe to your newsletter.

Re:Genius

[nuckfuts]

...no system is perfect.

The new method is not purported to be perfect. It does, however, allow people to measure a kilogram with as much accuracy as the current system without shipping reference weights around the world for comparison.

all units are reducible to Libraries of Congress

[Thud457]

Under the Slashdot Journalistic Standards and Practices accord of 2004, a kilogram is 1e-10 Libraries of Congress.

This makes dimensional analysis a lot easier.

Re:all units are reducible to Libraries of Congres

[Anonymous Coward]

I thought a Kilogram was defined as 1/200th of a KimKardashian...

So....

[cayenne8]

....all of those poor drug dealers are now going to have to re-balance their scales?

Come to think of it, for the most part in the US, doing anything like this to a metric measurement will have little effect as that hardly anything in "real daily life" here uses metric except the illegal drug trade.

Re:So....

[Hognoxious]

Every time this subject comes up you start wittering on about drug dealers. Do you think it makes you sound edgy or something.

P.S. Shouldn't you be in hiding from the caravan? Scary scary brown people who talk funny!

Re:So....

[hackertourist]

The pound is defined as a derivative of the kg, so yes this affects you too.

Re:So....

[cayenne8]

Every time this subject comes up you start wittering on about drug dealers. Do you think it makes you sound edgy or something.

No, just strikes me as kinda funny...and also my usual observation that the US doesn't use the metric system for anything in most citizens' real daily lives.

That no one really uses it here.

Re:So....

[The Grim Reefer]

No, just strikes me as kinda funny...and also my usual observation that the US doesn't use the metric system for anything in most citizens' real daily lives.

That no one really uses it here.

I know. I was just saying the same thing the other day when I picked up a 2 liter of soda and a bottle of 500mg aspirin at the store. While I was out, my daughter asked me to pick up a new set of headphones with a 3.5mm jack. Since I was at the store I picked up some new LED bulbs to lower my monthly kilowatt usage at home. That reminded me that I needed to order some new 80 and 120mm case fans for my desktop too. I'll probably add 16 more GB of RAM while I'm at it. On the way home some idiot in a 5.0 liter Ford Mustang cut in front of me and got out of his car carrying a baseball bat. Fortunately when he saw my Glock 9mm, he got back in his car and left 2 seconds later. I don't know how he knew I had my wife's 3 carat emerald ring in the car.

Re:So....

[Anonymous Coward]

total ownership of the idiot before you.

Re:So....

[Anonymous Coward]

that was...awesome!

Re: So....

[Anonymous Coward]

Cayanne8, paging cayanne8, you have been owned. Please report to lost and found to collect your balls. That is all, thank you!

Re:So....

[Anonymous Coward]

as that hardly anything in "real daily life" here uses metric except the illegal drug trade.

Except for the small matter that US units were redefined as exact multiples of metric units many years ago, so all US measures *are* metric with a constant thrown in, e.g. 1 inch was redefined as *exactly* 2.54 cm (which it wasn't originally). So you *are* (sort of) using metric, just a very clunky and inconvenient version.

Re:So....

[Anonymous Coward]

1Lb is defined as 0.45359237 kilograms. Even the imperial system is defined in units of the metric system. I still find it strange the the official definition of a unit of weight is defined in units of mass. Gravity field difference between cities is several magnitudes greater than the precision of the definition. Should have just defined the unit of a slug in kilograms, then left pounds defined in units of slugs and assumed gravitational strength.

Re:So....

[thegarbz]

car carrying a baseball bat

Baseball bat? Is that the imperial version of the cricket bat?

Re: Genius

[FuzzyDaddy2]

It is not the same thing. The kibble balance can be built to the required accuracy from scratch without using some artifact as a reference. It is not an artifact itself. Itâ(TM)s calibrated against physical phenomena.

Re:Genius

[thegarbz]

I understand: newer is always better.

Yeah I know. Defining the Kg to something fixed is right up there with replacing sysv with systemd.

unlike the old method, which was 0.000005%.

Plus and Minus a random change that makes it impossible to know what it was or will be for sure.

Re: Genius

[110010001000]

Exactly. All you need to do is build a $10 million balance system and regularly maintain and calibrate it in a clean room and you are fine. I wonder if you guys have even seen a Kibble balance. I guess it keeps the NIST budget going though.

Re:Genius

[110010001000]

Yeah, but with a Kibble balance you KNOW it is precise. Sure you do. Unless it is wrong.

Le Grand K is dead. Long live the Le Grand K

[140Mandak262Jamuna]

The hunk of platinum called le Grand K that defined the kilogram is not the standard anymore.

A Kibble balance, that will define the kilogram will built using platinum, iridium and other exotic metals. It will be housed in the double walled basement of SI building. This le Grand K(ibble) will be the standard Kibble balance against which all othe Kibble balances will be measured and tested against.

Re:Le Grand K is dead. Long live the Le Grand K

[religionofpeas]

The difference is that you can build additional Kibble balances from scratch, without using the existing ones as reference.

Build up a kilogram model one atom at a time?

[Anonymous Coward]

I know that we currently have the technology to build something up one molecule at a time, but do we have the technology to build something up one atom at a time? We know what the mass of an atom of any type of matter is, yes? If we could manipulate individual atoms, could we not build up exactly 1.00000000000...00000 kilograms of it?

Re:Build up a kilogram model one atom at a time?

[jeff4747]

but do we have the technology to build something up one atom at a time?

Not accurately enough. There'd be some extra or missing atoms in the final product.

Re:Build up a kilogram model one atom at a time?

[Anonymous Coward]

Sounds to me like something worth developing into something more practical.

Re:Build up a kilogram model one atom at a time?

[jeff4747]

All we'd have to do is invent some new physics so that we could do it accurately enough.

Weight != mass

[Roger W Moore]

A pound is a weight, not a mass which is not the same thing. While its definition may be based on the kilogram it must also be based on a value for the gravitational field since it is a force.

Measure g too

[Roger W Moore]

By it's very definition a balance in independent of gravity.

No it is not. Even a standard balance relies on the gravitational field for both sides being equal and, if you get precise enough, this may not be true. However, the watt balance balances the force of gravity with an electromagnetic force. Part of the measurement also requires determining the local gravitational field but this is something that you can measure accurately which is why this is still a far better definition than using a lump of metal outside Paris.

kilogram in terms of h equation

[Anonymous Coward]

In this case, the balance works by applying a magnetic field on one side, not a weight, so it's not independent of gravity.

The equation defining the kilogram in terms of h can be found in this Vox article (JPEG of a whiteboard drawing near the end):

* https://www.vox.com/science-and-health/2018/11/14/18072368/kilogram-kibble-redefine-weight-science

Mass Debaters

[Anonymous Coward]

Just had to say it... Mass debaters came to a conclusion on the definition of the kilogram.

You measure local gravitational acceleration

[Anonymous Coward]

Using an absolute gravimeter, which drops a weight in a vacuum and (using time and distance standards) measures how fast it accelerates. (More specifically, it drops a retroreflective "corner cube" which forms one arm of an interferometer and counts the fringes to see how fast it's moving. Also, the most accurate modern designs actually throw the weight from the bottom, so you get twice the flight time for a given height.)

Although not the most technically challenging part of operating a Kibble balance, this is a non-trivial exercise because local gravity changes depending on things like the position of the moon and the height of the local water table, and the site of the balance is carefully surveyed before construction so a gravity measurement beside the balance can be extrapolated to the gravity at the weighing position, which cannot be directly measured after the balance is installed.

The Kibble balance provides a known force, the absolute gravimeter tells you the acceleration, and you can plug them into Newton's law f = ma to find the mass.

Re: Genius

[Anonymous Coward]

Maintaining the IPK and all the other references that derive from it isn't free. And given how important accurate and repeatable measurements are to the modern world, $10 million is cheap.

AOL Inches

[Anonymous Coward]

Remember AOL inches? They may want to look at that.

Change yes, but which way?

[The Snazster]

I read the source article and nowhere did it say whether the new definition was heavier or lighter than the existing one. Inquiring minds want to know, after all, this stuff is not just exciting, it's really exciting!

Re:Change yes, but which way?

[Anonymous Coward]

You forget a third option. The definition changed but the raw value remained the same.

But yes, I too am wondering about this.

Re:Change yes, but which way?

[Anonymous Coward]

The original value was constantly changing and had a certain amount of uncertainty. The new value falls within that uncertainty, but it is now exactly defined with zero uncertainty. The only uncertainty left is not in the definition, but in the methodology and tools used to measure it.

how does kibble balance give accurate value?

[Anonymous Coward]

The accuracy of physical standard is the ability of copying the object. Thus two independent copies of the kilogram will have some difference. Mean value of such differences is the accuracy of kilogram.

The same applies to theoretical definitions. You provide a description of the experiment and if performed independently then the two copies should be close to each other. If these are more closer to each other than the physical copies then the theoretical definition is more accurate.

To get Kibble balance based kilo definition more accurate, one must be able to measure the current accurately. How is it done? How can you define a current theoretical way so that I can generate exact same amount of current myself in my lab to a very high precision (must only require me to use accurate clock and length measurements).

Give you 10 euros for the bar

[mnemotronic]

He, mes amis. Ten euros for that old, outdated slab of metal. No good to you anymore, no? Merci.

Re:Give you 10 euros for the bar

[sl3xd]

I don't think a five year old would fall for that one.

Besides, what's so special about le grand K? There are dozens of duplicates, all equally valuable platinum.

I ant wait to use it

[Anonymous Coward]

Pardon the pun

1 Kg = 1 Lb

[jfdavis668]

Next he will declare that P = NP and really screw up the world. Though I do like the 1 m = 3 ft part.

It is not a big moment

[jd]

A moment is defined as kg.m^2

The new definition is thus a unitary moment per unit area.

Pound is a mass

[jd]

https://en.m.wikipedia.org/wik...

It is exactly 0.45359237 kilograms

Re:Pound is a mass

[Pascoea]

I can wikipedia too! https://en.wikipedia.org/wiki/...

There is a definition for a pound in mass and and a pound in force (weight).

Re:Pound is a mass

[jd]

Yes, but you can't compare apples and urang utangs.

If the assertion is that pound is not mass, I do not have to prove that every definition fits that. It's the difference between "for all" and "there exists". That's why pound the currency isn't a useful sense. If I can show a sense exists that is indeed a mass, not a weight, then the post I replied to is wrong because it denied such a sense existed.

Your post shows their sense also exists, but that doesn't matter because I never asserted an exclusive sense, only the presence of a sense. Do you see the difference?

Re:Pound is a mass

[Pascoea]

Yes, your statement is pedantically correct. A "pound" can be expressed as a mass, disproving the OPs statement that a pound is a strictly a weight. But your post is also incomplete, in that it tends to imply that a pound is ONLY a mass. My intent was to point out that you were both correct.

Re:Pound is a mass

[Xenx]

Yes, your statement is pedantically correct. A "pound" can be expressed as a mass, disproving the OPs statement that a pound is a strictly a weight. But your post is also incomplete, in that it tends to imply that a pound is ONLY a mass. My intent was to point out that you were both correct.

Frankly, they're not the the pedantic one here. You are. If a person says one unit of measurement is based off of another unit of measurement, it would be proper to assume that the definition used for one of the terms of measurement was the one valid for the relational statement. It would be improper to assume the person was incorrectly using the wrong definition for one of the terms.

Re:Pound is a mass

[Roger W Moore]

If the assertion is that pound is not mass...

The pound cannot be a mass because otherwise "pounds per square inch" would be a unit of 2D density (like kilograms per square metre) and not a unit of pressure (like newtons per square metre). The imperial unit of mass is, according to wikipedia, the slug. If you try to use the pound for both weight and mass then you have a system of units which is inconsistent with basic physics. Indeed the fact that imperial units appear to rely on the definition of a force in terms of a mass really just demonstrates how utterly nuts they are.

Re:Pound is a mass

[jd]

You are conflating many different definitions and assuming a grandiose revelation.

All you reveal is that you're an idiot.

The definition of psi is pound-force, not pound-mass.

These are not, repeat not, the same thing although both called a pound.

I have no further time to waste on your ignorance of imperial units. Or, indeed, your ignorance in general.

The better question for me is:

[Anonymous Coward]

Since this now requires lasers and other ultra-precise devices to provide the reference weight of a kilogram: Who is working on the fully documented bootstrap guide to doing all this from scratch in the case of a cataclysm or apocalypse?

Both the original Iridium(Titanium?) cylinder and the newly updated kilogram standard rely on technology or engineering beyond the common man. And without proper documentation of it, a significant event, like a world war, could in fact leave us in a state where the scientists and manufacturing talent necessary to keep these references possible have been torn down, in which case half of our precision science goes out the window because we have no way to recreate the weight or time standards necessary for precision beyond the laymans level, and even that could deviate over time without the 'constant', neither version of which is reproducible without current knowledge that is not broadly public.

If someone can produce a guide going from the initial technlogies a layman could reproduce and include all later technologies and knowledge required to reproduce the weight, time, and distance references, we would be in a lot better condition, whether sending colonists to remote worlds, or bringing society back to modern technological levels after the next Dark Age.

Re:The better question for me is:

[Hognoxious]

I think if there's such a calamity we won't give a shit about having accurate measurements, we'll be trying to avoid being eaten.

We got from length of the king's arm to the distance light travels in so many vibrations of a something atom. When the need arises, we can do it again.

Re:The better question for me is:

[Anonymous Coward]

You can either use what you have or what you know. What you know is based on precises measurements using universal constants. The higher the precision, the more accurate the definition. What everyone has used to use until this event is what they have. Someone had something, but no one else could have it, and the act of using it changed it. It worked good enough for many many years, but in the long run, we can't have our units of measurement changing and inaccessible without defiling it.

There is nothing saying that we have to use the most bleeding edge of technology to implement the measurements, but if you want to measure within a currently acceptable deviation of error, you need this most extravagant setup. In the case of an end of the world situation, we could use much more crude devices, but the error in measurement will be much higher.

You do bring up a great point. We should have a boot-strapping process. It doesn't need to be perfect, we can make it more accurate and precises as the technology is recreated.

A little concerned

[jd]

The second is out of date. Caesium is a horribly outdated method of measuring time. Modern atomic clocks, using strontium quantum gasses, are roughly ten orders of magnitude better.

But because of how the second is defined, you can't use a more accurate clock. The errors in caesium clocks are part of the definition. Remove the error and you're not measuring seconds even if you're measuring more accurately.

It's probably better to use fundamental units as the starting point, or at least something close, rather than arbitrary objects in nature.

Ideally, it shouldn't matter if things get measured more accurately, you won't break anything.

If you can't do that, then the definitions should be aiming at the ten orders more accurate results that can be obtained.

As for constants, they should be justified geometrically, kept simple, or defined in terms of underlying physics.

Re:A little concerned

[Anonymous Coward]

https://www.sciencemag.org/new...

I still prefer natural units though.

[Anonymous Coward]

They are only based on universal constants. They use another, completely arbitrary constant on top of that. Making everything more complicated, but seemingly easier merely because it's what we're used to. Not because it would be actually better. Because, as I said: It is completely arbitrary.

Natural units (Planck units) would be better. And backwards compatible too, since you could still use prefixes that contain those arbitrary other constants, if you really needed to, and the normal SI prefixes wouldn't already do it. (Normally, they definitely would.)

I'm amazed there's a moron(+) for every moron(-).

[Anonymous Coward]

You're just as much a moron. You could have easily ridiculed his argument. But you used a logically invalid appeal to authority fallacy (or appeal to lack of authority, in this case) instead. Making your argument just as invalid as his, and putting yourself at the same level.
Great job. *slow clap*

[But I guess you just learned from our dark ages legal system, where every crime is righteous, if you just find an excuse about how your victim committed the mirror of the same crime. Or not even the mirror. Murder: Wrong. Murder of a murderer: Somehow "not" murder, but "right". Murder of a murderer of a murderer: Somehow wrong again. ... It makes no sense, until you realize that who's the murderer and who's the righteous solely and exclusively depends on who's currently in power. Either actually, or at the water cooler / cracker barrel.]

Re: Genius

[Anonymous Coward]

With any scale you never know if it is broke or not. Therefore mass is a meaningless concept.

Re: Genius

[Anonymous Coward]

Some of the Kibble balance components, like the resistance/voltage/current standards and local gravity calibration, are orders of magnitude cheaper than they used to be as development pushed the components from national labs to instrumentation companies. Time standards based on atomic clocks were once too expensive except for a few national labs, and now are available commercially on an integrated package the size of a surface mount chip. These things get cheaper and commercialized once the exact method I'd no longer prescribed and definitions move to basic physics.

Clueless or troll?

[sjbe]

I know exactly what they did.

Evidently not.

But apparently you don't, based on your "explanation".

Again, I can't tell if you are trolling or just ignorant. Either way what you said is demonstrably wrong.

Pounds all the way down

[Roger W Moore]

These are not, repeat not, the same thing although both called a pound.

That's my point though: using pounds for both mass and force makes imperial units unfit for use because you have no way of knowing what it is that I measured which is entirely the problem that using units is supposed to solve. It also leads to utterly stupid units, for example, you could measure acceleration in pounds per pound even though that looks like a dimensionless unit. Units of pounds-squared has three different possible interpretations etc. It is just nuts.

Indeed since you seem so enamoured with this useless system why not define a pound-length, a pound-time etc. and then you can just use pounds^n to measure everything. Of course, there will be no way for anyone to know exactly what you measured but that's already pretty much the case and at least now you'll only have one unit to remember for everything.