https://www.nature.com/articles/s41586-023-06491-w "We foresee the development of a Sc-based nuclear clock in the future" However "Every X-ray pulse train with an energy of about 65 mJ heats the 25-μm thick Sc-metal target by an estimated temperature of about 100 K. The heat conductivity of Sc metal is low—15.8 W m−1 K−1, comparable to that of stainless steel. Radiation damage to the target is thus inevitable. Special measures were taken to avoid damage, including water and air cooling, defocusing of the beam (the beam footprint was about 2 mm2) and periodic replacement of the target. Two targets had to be replaced in the course of the experiment because of partial radiation damage." Methinks that's a fairly critical issue (-: Cheers Arne

A nuclear clock may be less susceptible to various perturbations, but will still have a frequency that is a function of gravity, as per relativity. Has a way of measuring gravity been developed that would be accurate enough to make such a nuclear clock as accurate as this article is saying? --- Rick Karlquist N6RK On 2023-10-02 11:18, shouldbe q931 via time-nuts wrote: > https://www.nature.com/articles/s41586-023-06491-w > > "We foresee the development of a Sc-based nuclear clock in the future" > > However > > "Every X-ray pulse train with an energy of about 65 mJ heats the 25-μm > thick Sc-metal target by an estimated temperature of about 100 K. The > heat conductivity of Sc metal is low--15.8 W m-1 K-1, comparable to > that of stainless steel. Radiation damage to the target is thus > inevitable. Special measures were taken to avoid damage, including > water and air cooling, defocusing of the beam (the beam footprint was > about 2 mm2) and periodic replacement of the target. Two targets had > to be replaced in the course of the experiment because of partial > radiation damage." > > Methinks that's a fairly critical issue (-: > > Cheers > > Arne > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Rick: There are a number of ways to measure gravity, but the best that I know of is the Super conducting type. One of these was used to cancel the Earth's tide motion of a telescope used for ranging retro-reflectors on the Moon.  i.e. good enough to detect feet/inches of movement of granite rock. https://prc68.com/I/GravityMeters.shtml#Super_Conducting Tom's experiment with moving an atomic clock would give you the a rough translation factor between gravity and time, if like me you're not conversant with Einstein's equations. My guess is that the above gravity meter would be good to much better than a part in 10,000. I don't think GPS can be used since placing a GPS antenna on an atomic clock would probably result in no signal.  And running an atomic clock in a location with a clear view of the sky may  not be the best location interms of clock accuracy.  Something Tom maybe could comment on. -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. -------- Original Message -------- > A nuclear clock may be less susceptible to various perturbations, but > will still have a frequency that is a function of gravity, as per > relativity. > > Has a way of measuring gravity been developed that would be accurate > enough to make such a nuclear clock as accurate as this article is > saying? > > --- > Rick Karlquist > N6RK > > On 2023-10-02 11:18, shouldbe q931 via time-nuts wrote: > >> https://www.nature.com/articles/s41586-023-06491-w >> >> "We foresee the development of a Sc-based nuclear clock in the future" >> >> However >> >> "Every X-ray pulse train with an energy of about 65 mJ heats the 25-μm >> thick Sc-metal target by an estimated temperature of about 100 K. The >> heat conductivity of Sc metal is low--15.8 W m-1 K-1, comparable to >> that of stainless steel. Radiation damage to the target is thus >> inevitable. Special measures were taken to avoid damage, including >> water and air cooling, defocusing of the beam (the beam footprint was >> about 2 mm2) and periodic replacement of the target. Two targets had >> to be replaced in the course of the experiment because of partial >> radiation damage." >> >> Methinks that's a fairly critical issue (-: >> >> Cheers >> >> Arne >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Brooke, > There are a number of ways to measure gravity, > but the best that I know of is the Super conducting type. There is at least one commercial model available. Start here: https://www.gwrinstruments.com/pdf/principles-of-operation.pdf For more practical high-performance gravimeters, see the six models listed at this site:     https://microglacoste.com/shop/ If you want wonderful details a full set of brochures and manuals is available under the Support tab. > Tom's experiment with moving an atomic clock would give you > the a rough translation factor between gravity and time Yes, relativity theory predicts -- and many experiments confirm -- that gravity affects time. The closer to a massive object you get the lower the frequency (called redshift) of your clock. For planet earth the fractional change in frequency, df/f, is approximately 1e-16 per meter, or 1e-13 per km. I think that's what you meant by translation factor. It's very, very small. Note that a frequency difference of 1e-13 is a phase drift of about 10 ns per day. This means if you have clocks that are good to 1e-14 and you perform a 1 km experiment (one clock low, one clock high) for 2 days you'll see about 20 ns of time dilation. This actually works, as you know from the hp 5071A experiments I've done on different mountains over the years. > I don't think GPS can be used ... > Something Tom maybe could comment on. I don't understand that paragraph. Please clarify so I don't go off on a tangent. /tvb On 10/4/2023 11:59 AM, Brooke Clarke via time-nuts wrote: > Hi Rick: > > There are a number of ways to measure gravity, but the best that I > know of is the Super conducting type. > One of these was used to cancel the Earth's tide motion of a telescope > used for ranging retro-reflectors on the Moon.  i.e. good enough to > detect feet/inches of movement of granite rock. > https://prc68.com/I/GravityMeters.shtml#Super_Conducting > > Tom's experiment with moving an atomic clock would give you the a > rough translation factor between gravity and time, if like me you're > not conversant with Einstein's equations. > My guess is that the above gravity meter would be good to much better > than a part in 10,000. > > I don't think GPS can be used since placing a GPS antenna on an atomic > clock would probably result in no signal.  And running an atomic clock > in a location with a clear view of the sky may  not be the best > location interms of clock accuracy.  Something Tom maybe could comment > on. >