Jim, The CIPM (who have responsibility for producing the SI Brochure) have 10 consultative committees who look at various aspects of the CIPM's work - length, acoustics, mass, thermometry etc. Apart from the CCU (Consultative Committee on Units), these CCs are filled with CIPM nominees. The CIPM appoint the chairman of the CCU, but rest of the committee is made up of members from other bodies including ISO, NIST, NPL, IUPAC, IUPAP, IAU etc.
Regards Martin -----Original Message----- From: owner-u...@colostate.edu [mailto:owner-u...@colostate.edu] On Behalf Of James Sent: 06 January 2014 14:34 To: U.S. Metric Association Subject: [USMA:53493] Re: Draft for chapters 1-3 of the next SI Brochure Paul, I'm going to answer this on the list since others likely will have the same questions. When you get further into the document, you will see that it points out the watt balance as being essential for macroscopic determinations of mass at the primary local standards level. Yes, this would fix the Avogadro number for everyone. Recall that IUPAC and IUPAP are involved in this effort! Jim On 2014-01-06 08:20, Paul Trusten wrote: > Jim, this is quite exciting! I shall have to sit down and compare the current SI Brochure with the draft. > > It seems like a clever strategy to define the constants in terms of the base units, so that the base units then become defined by the constants. I don't know if I'm asking the right question, but here goes. Does this definition plan eliminate the need for the watt balance and other experiments on redefining the kilogram, since the Planck constant henceforth shall be exactly defined? > > Also, once the BIPM defines the Avogadro constant exactly, does that definition indeed become binding on physics and chemistry? It never occurred to me until now that the keepers of the world measurement system might also be the keepers of definitions that affect disciplines beyond metrology. Perhaps this is why consultative committees exist. I don't really know how this actually works. > > > Paul > > Paul Trusten, Registered Pharmacist > Vice President and Public Relations Director U.S. Metric Association, > Inc. > Midland, Texas, USA > +1(432)528-7724 > www.metric.org > trus...@grandecom.net > > >> On Jan 5, 2014, at 16:42, James <j...@metricmethods.com> wrote: >> >> Dear USMA Folks, >> >> The next edition (the ninth) of the SI Brochure is likely to reflect, as you know, the shift to using seven exactly defined natural constants as the basis for the SI. The process of defining values for those constants in appropriate units effectively defines the SI base units. Currently, the likely date of publication of the final draft for edition 9 will be in 2018, give or take. >> >> In anticipation of this, work has progressed in re-writing the SI Brochure. I have posted here previous drafts of small sections of the new material in the past, as well as some underlying documents that discuss the nature of that shift of emphasis. >> >> Now, a major portion of the new version of the Brochure's first three chapters is available, courteously provided to us by Barry Taylor (NIST, CCU). You may view the draft at, and download it from: >> http://www.bipm.org/utils/common/pdf/si_brochure_draft_ch123.pdf >> >> I have, so far, carefully read the first several pages (of 29) and have skimmed the rest. Clearly this is a major rewriting of the Brochure and not a tweak to update it. That is, it is a fresh start and not a patch. >> >> So far, I am greatly impressed. The text flow starts "ab initio" in the field of metrology and quickly develops the system from there. The flow of information is smooth and clear to the careful reader -- at least one experienced in the SI. And one **should** read it carefully. Like any good technical writing the information content is concentrated; no blathering appears in this document and every word is essential. >> >> I will continue my careful study of this document. But in the meantime I would like to put it out here on the list for you to see. Hopefully this will start a lively and relevant discussion. One criterion that I think we should gauge it by is how accessible it is to the neophyte, the student, the general but decently educated member of the public. In short, is it "teachable"? So far as I have read it, I think that it is. >> >> Now, let's hear your opinions! >> >> Enjoy! >> >> Jim Frysinger >> Chair, IEEE SCC14 >> >> > > >
