Hi
> On Apr 23, 2018, at 12:21 AM, Bill Hawkins <bill.i...@pobox.com> wrote: > > Good questions. > > The one that bothers me is the magnetic levitation required to compare > the standard to anything. You can't put other materials inside the > vacuum bell with the standard. I looked up the paper, but it's behind a > $40 pay-wall. > > Electromagnets will levitate permanent magnets, but the effect is not > stable, with the free magnet sliding out of the field. > Diamagnetic materials will be stable, but the effect is so weak it would > require superconducting electromagnets. Quartz, as it happens, is > diamagnetic. > > Now the problem is to apply identical levitation to dissimilar > materials. This would seem to require identical superconducting magnets > and identical levitated platforms. Identical currents can flow in the > levitating magnets simply by connecting them in series. In order for the > platforms to be identically levitated, they have to be an identical > distance from the levitating magnet. Measuring that to the required > precision could be a challenge. > > Machining physical parts can be done to 10 E-6. That's not enough, so > the mechanism will require calibration. I suppose they could compare it > to the present platinum standard. Then there's the question of > calibration interval, and what to use as the standard. Counting > oscillations of atoms would be so much easier. > > I think Rick's three points make this a non-starter. It's a case of > experts in metrology not having enough expertise in quarts resonators. Just for the record John Vig knows quite a bit about quartz resonators …. Bob > > In answer to why they can't use 10 grams, the comparison has to be 100 > times more accurate than that for 1000 grams. > > Hope I haven't strayed too far off topic, and wasted my time. > > Bill Hawkins > > > -----Original Message----- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard > (Rick) Karlquist > Sent: Sunday, April 22, 2018 4:11 PM > To: Discussion of precise time and frequency measurement; Bob kb8tq > Subject: Re: [time-nuts] Better quartz crystals with single isotope ? > > On 4/22/2018 10:20 AM, Bob kb8tq wrote: > >>> Do we know anybody in the quartz business who needs a really cool >>> research project ? >> >> You could put it on the list with the 1 Kg quartz resonator proposal > ... >> >> https://tf.nist.gov/general/pdf/2638.pdf >> <https://tf.nist.gov/general/pdf/2638.pdf> >> >> Also an offshoot of people thinking about the implications of all this > as it relates to resonators. >> >> >> Bob >> > > The cited article "must be true" because of its authors, I guess, but it > makes no sense to me. They seem to be assuming that the resonant > frequency is inversely proportional to mass? We all know three things: > > 1. Frequency is inversely proportional to thickness. Not mass. > > 2. Frequency aging is affected by stress relaxation in well built > resonators. The old idea that mass is gradually evaporating from the > resonator to the enclosure (glass enclosures) or mass is gradually > evaporating from the enclosure (metal enclosures) to depositing on the > resonator is simply obsolete in terms of current technology. > Thus again frequency is not a proxy for mass. > > 3. Resonators can "jump" in frequency without jumping in mass. > > Given these facts, I am lost as how this is supposed to work. > Surely, the authors are well aware of the 3 items above. > > Also, why does the resonator have to be a whole kilogram anyway. > If it weighed exactly 10 grams, couldn't you still compare it to a > kilogram using 100:1 leverage? > > Can anyone straighten me out? > > Rick > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.