Is there a yearly convention with this Club Poor somewhere?
Yes, but I am not allowed in. They say that someone who has lived his whole life in rich countries with a good education and lots of opportunities, who has never passed through real difficulties and who can even afford to not be too worried about money (despite not having much) can't be considered poor. That's why I refer to myself as kind of poor. And I haven't been able to find any Club Kind of Poor:)
Maybe he did it on credit cards, hoping to go viral and make it all back?
No idea. Times are weird. Something like that and even much crazier might pay off, at least temporarily. Because there is something which hasn't changed and will probably never do: if you are rich, the doors are wide open; otherwise, you might get a chance to open them a bit and, after that, you would have to continue making efforts to keep them open.
If this is about a rich family (just rich enough to afford expenses of this sort and to have the required background, contacts and long-term expectations), this experiment would probably represent an excellent starting point for the almost-certainly brilliant future of that kid. If this is about other kind of family (one not able to afford all this and without the required status/contacts, but understanding the importance of being known, getting a proper education, etc.), the kid might have a couple of good chances which he would have to maximise; after that, new opportunities might arise, but he would always have to prove himself and be better than others; and so on and so forth, until the point where that kid becomes a man with a really brilliant future or not, because he eventually failed (fairly or arbitrarily) or gave up or stopped seeing the point of continuing or any other thing happened. I personally prefer the not-so-rich version because, in that scenario, the chances of this kid to become a worthy human being seem much higher.
When I was 12, I spent all my fusion-power allowance ($10000 in equipment + electricity bills + equipment maintenance + further learning/helping resources) in toys and candies. I guess that this is the reason why I am (kind of) poor now. LOL
Just by converting that "uses" into "generates", we would get usable fusion power! He is soooo close! Why not trying with a bigger dictionary or something? He should definitively scale his vocabulary up! LOL.
IT-related standards from renowned organisations and certain governments/public institutions. And I am saying this despite trusting a lot in my expertise and systematically relying on learning-from-practice ideas.
There are many options depending on the exact problem, but I have found lots of nice (and completely free!) stuff from IETF, NIST and EU organisations. From detailed instructions about how to reliably account for the slightest issue, up to pretty light but informative guides about quite generic aspects.
As a terrible salesman, my opinion about what should (not) be done is worth nothing. As a random viewer and potential client, I can say that a so marketing-intensive setup is very unappealing to me. Much more when dealing with a theoretically "cold" reality, where accurate and properly-justified numbers seem the only important thing. If you are selling cakes, slightly increasing the amount of sugar might be a good idea; but certainly not if you are selling steaks.
The linked article is a masterpiece! So cool names and animals for the state actors! And look at the Mummy Spider below! What a tremendous job! 20 minutes, 3 hours or 5 years, it doesn't matter! Simple values which anyone could easily input into that well-crafted graphical heaven! I don't know what you are selling, but I want 10 of each! Please, take my money!! LOL.
I used to love the idea of programming-intensive interviews, as a way to objectively assess my most-relevant-to-the-job skills. After doing quite a few them, I realised about my mistake. A theoretically excellent proceeding becomes really bad when being terribly mismanaged, what is a surprisingly common scenario in the IT/programming world.
I never had to solve a really difficult problem, but lots of them under unreasonably short time constraints (i.e., the holy grail of arbitrary, cheating-prone, useless-parrot filters). Now, I prefer to avoid these situations, unless when knowledgeable people and reasonable conditions are involved.
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).
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.
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:)
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.
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
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.
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.
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.
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.
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
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).
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.
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.
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.
Slashdot Mirror
Apparently, this alternative is even more theoretical and difficult than the typical fusion approaches with steam-based electricity generation.
Is there a yearly convention with this Club Poor somewhere?
Yes, but I am not allowed in. They say that someone who has lived his whole life in rich countries with a good education and lots of opportunities, who has never passed through real difficulties and who can even afford to not be too worried about money (despite not having much) can't be considered poor. That's why I refer to myself as kind of poor. And I haven't been able to find any Club Kind of Poor :)
Maybe he did it on credit cards, hoping to go viral and make it all back?
No idea. Times are weird. Something like that and even much crazier might pay off, at least temporarily. Because there is something which hasn't changed and will probably never do: if you are rich, the doors are wide open; otherwise, you might get a chance to open them a bit and, after that, you would have to continue making efforts to keep them open.
If this is about a rich family (just rich enough to afford expenses of this sort and to have the required background, contacts and long-term expectations), this experiment would probably represent an excellent starting point for the almost-certainly brilliant future of that kid. If this is about other kind of family (one not able to afford all this and without the required status/contacts, but understanding the importance of being known, getting a proper education, etc.), the kid might have a couple of good chances which he would have to maximise; after that, new opportunities might arise, but he would always have to prove himself and be better than others; and so on and so forth, until the point where that kid becomes a man with a really brilliant future or not, because he eventually failed (fairly or arbitrarily) or gave up or stopped seeing the point of continuing or any other thing happened. I personally prefer the not-so-rich version because, in that scenario, the chances of this kid to become a worthy human being seem much higher.
When I was 12, I spent all my fusion-power allowance ($10000 in equipment + electricity bills + equipment maintenance + further learning/helping resources) in toys and candies. I guess that this is the reason why I am (kind of) poor now. LOL
equipment that uses 50,000 volts of electricity
Just by converting that "uses" into "generates", we would get usable fusion power! He is soooo close! Why not trying with a bigger dictionary or something? He should definitively scale his vocabulary up! LOL.
PS: I don't wish to have discovered the IT standards sub-world before. Or pretty much any other thing. Carpe diem, baby! :)
IT-related standards from renowned organisations and certain governments/public institutions. And I am saying this despite trusting a lot in my expertise and systematically relying on learning-from-practice ideas. There are many options depending on the exact problem, but I have found lots of nice (and completely free!) stuff from IETF, NIST and EU organisations. From detailed instructions about how to reliably account for the slightest issue, up to pretty light but informative guides about quite generic aspects.
As a terrible salesman, my opinion about what should (not) be done is worth nothing. As a random viewer and potential client, I can say that a so marketing-intensive setup is very unappealing to me. Much more when dealing with a theoretically "cold" reality, where accurate and properly-justified numbers seem the only important thing. If you are selling cakes, slightly increasing the amount of sugar might be a good idea; but certainly not if you are selling steaks.
The linked article is a masterpiece! So cool names and animals for the state actors! And look at the Mummy Spider below! What a tremendous job! 20 minutes, 3 hours or 5 years, it doesn't matter! Simple values which anyone could easily input into that well-crafted graphical heaven! I don't know what you are selling, but I want 10 of each! Please, take my money!! LOL.
I used to love the idea of programming-intensive interviews, as a way to objectively assess my most-relevant-to-the-job skills. After doing quite a few them, I realised about my mistake. A theoretically excellent proceeding becomes really bad when being terribly mismanaged, what is a surprisingly common scenario in the IT/programming world.
I never had to solve a really difficult problem, but lots of them under unreasonably short time constraints (i.e., the holy grail of arbitrary, cheating-prone, useless-parrot filters). Now, I prefer to avoid these situations, unless when knowledgeable people and reasonable conditions are involved.
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).
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.
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
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.
:)) 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).
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
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.
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
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.
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.
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.
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.
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
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).
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.
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.
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.
Logically, the intention of my pun was "I guess that you meant force rather than weight". Because grams definitively measure mass.