fiber.guru@fiber.guru said: > One thing that was pretty cool is that NIST developed a fountain clock that > is so accurate it is influenced by altitude. They had to raise the clock > once to install a new floor beneath and when they raised the clock it > impacted the frequency. Originally discouraged by this it suddenly occurred > to someone that they had developed an extremely accurate way to measure > height! Now they just have to miniaturize it and make it affordable (of > course this is the bane of laboratory experiments). Time Too Good to Be True, Daniel Kleppner Physics Today, March 2006, page 10 https://physicstoday.scitation.org/doi/10.1063/1.2195297 -- These are my opinions. I hate spam.

> Time Too Good to Be True, Daniel Kleppner > Physics Today, March 2006, page 10 > https://physicstoday.scitation.org/doi/10.1063/1.2195297 An adventure in relative time-keeping, Tom Van Baak Physics Today, March 2007, page 16 https://physicstoday.scitation.org/doi/10.1063/1.2718741 /tvb

Hi So there might be a reason (other than NIST) to believe that frequency and gravity are related to each other ? :) Bob > On Oct 30, 2020, at 7:28 AM, Tom Van Baak <tvb@LeapSecond.com> wrote: > > > Time Too Good to Be True, Daniel Kleppner > > Physics Today, March 2006, page 10 > > https://physicstoday.scitation.org/doi/10.1063/1.2195297 > > An adventure in relative time-keeping, Tom Van Baak > Physics Today, March 2007, page 16 > https://physicstoday.scitation.org/doi/10.1063/1.2718741 > > /tvb > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

The NIST seminars are interesting, but if you attend multiple years the material is nearly always the same. db -----Original Message----- From: time-nuts <time-nuts-bounces@lists.febo.com> On Behalf Of Bob kb8tq Sent: Friday, October 30, 2020 7:56 AM To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com> Subject: Re: [time-nuts] "When you google word ..." Hi So there might be a reason (other than NIST) to believe that frequency and gravity are related to each other ? :) Bob > On Oct 30, 2020, at 7:28 AM, Tom Van Baak <tvb@LeapSecond.com> wrote: > > > Time Too Good to Be True, Daniel Kleppner Physics Today, March 2006, > > page 10 > > https://physicstoday.scitation.org/doi/10.1063/1.2195297 > > An adventure in relative time-keeping, Tom Van Baak Physics Today, > March 2007, page 16 > https://physicstoday.scitation.org/doi/10.1063/1.2718741 > > /tvb > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go > to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.

Was the blueshift only ever tested by using atomic clocks? OK, OCXOs alone are not stable enough to try and we can't go that far from our planet with the necessary equipment. On Fri, Oct 30, 2020 at 2:27 PM Bob kb8tq <kb8tq@n1k.org> wrote: > > Hi > > So there might be a reason (other than NIST) to believe that frequency and > gravity are related to each other ? :) > > Bob > > > On Oct 30, 2020, at 7:28 AM, Tom Van Baak <tvb@LeapSecond.com> wrote: > > > > > Time Too Good to Be True, Daniel Kleppner > > > Physics Today, March 2006, page 10 > > > https://physicstoday.scitation.org/doi/10.1063/1.2195297 > > > > An adventure in relative time-keeping, Tom Van Baak > > Physics Today, March 2007, page 16 > > https://physicstoday.scitation.org/doi/10.1063/1.2718741 > > > > /tvb > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

Azelio, Right, OCXO are not stable enough at the desired tau to do a blueshift experiment. So that's why atomic (and now, optical) clocks are used. But note that many experimental confirmations of general relativity, from planets to black holes, do not involve clocks, per se. See, for example: https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment Here's a historical summary of GR experiments from a Physics textbook: https://www.relativity.li/uploads/pdf/English/I_en.pdf Another good list: https://en.wikipedia.org/wiki/Tests_of_general_relativity And Clifford Will's classic: https://link.springer.com/article/10.12942/lrr-2014-4 https://arxiv.org/abs/1403.7377 /tvb On 10/30/2020 7:44 AM, Azelio Boriani wrote: > Was the blueshift only ever tested by using atomic clocks? OK, OCXOs > alone are not stable enough to try and we can't go that far from our > planet with the necessary equipment. > > On Fri, Oct 30, 2020 at 2:27 PM Bob kb8tq <kb8tq@n1k.org> wrote: >> Hi >> >> So there might be a reason (other than NIST) to believe that frequency and >> gravity are related to each other ? :) >> >> Bob >> >>> On Oct 30, 2020, at 7:28 AM, Tom Van Baak <tvb@LeapSecond.com> wrote: >>> >>>> Time Too Good to Be True, Daniel Kleppner >>>> Physics Today, March 2006, page 10 >>>> https://physicstoday.scitation.org/doi/10.1063/1.2195297 >>> An adventure in relative time-keeping, Tom Van Baak >>> Physics Today, March 2007, page 16 >>> https://physicstoday.scitation.org/doi/10.1063/1.2718741 >>> >>> /tvb >>> >>> >>>