Discussion:
Detecting gravity with optical atomic clocks
Add Reply
John Moran, Scawby Design
2018-11-30 17:35:56 UTC
Reply
Permalink
Surely, this is nothing new?

I thought standard pendulum clocks were quite good at detecting gravity as well!

They make excellent earth-quake detectors - Randall Peters published many excellent papers on this subject many years ago, fascinating stuff.

John Moran
_______________________________________________
time-nuts mailing list -- time-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Tom Van Baak
2018-12-01 13:17:49 UTC
Reply
Permalink
Post by John Moran, Scawby Design
Surely, this is nothing new?
Once or twice a year some national lab, often NIST, makes an announcement of a new level of precision for their atomic clocks. It's pretty cool, actually. It's good PR. The rate of progress is amazing.
Post by John Moran, Scawby Design
I thought standard pendulum clocks were quite good at detecting gravity as well!
Yes and no. Modern uses for precision gravity measurement often require precise data while flying or in orbit. Pendulum clocks don't do well in those conditions.
Post by John Moran, Scawby Design
They make excellent earth-quake detectors - Randall Peters published many excellent papers on this subject many years ago, fascinating stuff.
Yes. For example, see the pendulum results of yesterday's earthquake:

http://leapsecond.com/pend/synchronome/quake.htm
Post by John Moran, Scawby Design
John Moran
/tvb


_______________________________________________
time-nuts mailing list -- time-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Paul Bicknell
2018-12-01 13:40:14 UTC
Reply
Permalink
Hi John

Any chance of a picture of your Synchronome pendulum clock and associated
timing / logging equipment

Paul B

-----Original Message-----
From: time-nuts [mailto:time-nuts-***@lists.febo.com] On Behalf Of Tom
Van Baak
Sent: 01 December 2018 13:18
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Detecting gravity with optical atomic clocks
Post by John Moran, Scawby Design
Surely, this is nothing new?
Once or twice a year some national lab, often NIST, makes an announcement of
a new level of precision for their atomic clocks. It's pretty cool,
actually. It's good PR. The rate of progress is amazing.
Post by John Moran, Scawby Design
I thought standard pendulum clocks were quite good at detecting gravity as well!
Yes and no. Modern uses for precision gravity measurement often require
precise data while flying or in orbit. Pendulum clocks don't do well in
those conditions.
Post by John Moran, Scawby Design
They make excellent earth-quake detectors - Randall Peters published many
excellent papers on this subject many years ago, fascinating stuff.

Yes. For example, see the pendulum results of yesterday's earthquake:

http://leapsecond.com/pend/synchronome/quake.htm
Post by John Moran, Scawby Design
John Moran
/tvb


_______________________________________________
time-nuts mailing list -- time-***@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.



-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18
Internal Virus Database is out of date.


_______________________________________________
time-nuts mailing list -- time-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Didier Juges
2018-12-01 14:13:41 UTC
Reply
Permalink
Tom,
I suspect something so sensitive gives you significant "false positives"
when a delivery truck goes by. I assume you try to correlate your data with
other enthusiasts nearby to resolve those discrepancies the way we do with
our clocks?

Didier
Post by Paul Bicknell
Hi John
Any chance of a picture of your Synchronome pendulum clock and associated
timing / logging equipment
Paul B
-----Original Message-----
Van Baak
Sent: 01 December 2018 13:18
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Detecting gravity with optical atomic clocks
Post by John Moran, Scawby Design
Surely, this is nothing new?
Once or twice a year some national lab, often NIST, makes an announcement of
a new level of precision for their atomic clocks. It's pretty cool,
actually. It's good PR. The rate of progress is amazing.
Post by John Moran, Scawby Design
I thought standard pendulum clocks were quite good at detecting gravity
as
well!
Yes and no. Modern uses for precision gravity measurement often require
precise data while flying or in orbit. Pendulum clocks don't do well in
those conditions.
Post by John Moran, Scawby Design
They make excellent earth-quake detectors - Randall Peters published many
excellent papers on this subject many years ago, fascinating stuff.
http://leapsecond.com/pend/synchronome/quake.htm
Post by John Moran, Scawby Design
John Moran
/tvb
_______________________________________________
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.8048 / Virus Database: 4793/15883 - Release Date: 08/14/18
Internal Virus Database is out of date.
_______________________________________________
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-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Bob kb8tq
2018-12-01 14:20:31 UTC
Reply
Permalink
Hi

There are indeed “Gravity Nuts” who would scoff at the limited sensitivity of a conventional clock
as a gravity measurement device……Lots of interesting hobbies to fiddle with ….

Bob
Post by Tom Van Baak
Post by John Moran, Scawby Design
Surely, this is nothing new?
Once or twice a year some national lab, often NIST, makes an announcement of a new level of precision for their atomic clocks. It's pretty cool, actually. It's good PR. The rate of progress is amazing.
Post by John Moran, Scawby Design
I thought standard pendulum clocks were quite good at detecting gravity as well!
Yes and no. Modern uses for precision gravity measurement often require precise data while flying or in orbit. Pendulum clocks don't do well in those conditions.
Post by John Moran, Scawby Design
They make excellent earth-quake detectors - Randall Peters published many excellent papers on this subject many years ago, fascinating stuff.
http://leapsecond.com/pend/synchronome/quake.htm
Post by John Moran, Scawby Design
John Moran
/tvb
_______________________________________________
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-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.
djl
2018-12-01 16:16:24 UTC
Reply
Permalink
Where does the relaxation time of ~ 1 hr arise??
Don
Post by Tom Van Baak
Post by John Moran, Scawby Design
Surely, this is nothing new?
Once or twice a year some national lab, often NIST, makes an
announcement of a new level of precision for their atomic clocks. It's
pretty cool, actually. It's good PR. The rate of progress is amazing.
Post by John Moran, Scawby Design
I thought standard pendulum clocks were quite good at detecting gravity as well!
Yes and no. Modern uses for precision gravity measurement often
require precise data while flying or in orbit. Pendulum clocks don't
do well in those conditions.
Post by John Moran, Scawby Design
They make excellent earth-quake detectors - Randall Peters published
many excellent papers on this subject many years ago, fascinating
stuff.
http://leapsecond.com/pend/synchronome/quake.htm
Post by John Moran, Scawby Design
John Moran
/tvb
_______________________________________________
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
--
Dr. Don Latham AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


_______________________________________________
time-nuts mailing list -- time-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.
Anders Wallin
2018-12-01 21:02:10 UTC
Reply
Permalink
on the subject of pendulum vs. optical:
please don't mix sensitivity to "g" directly with sensitivity to the
gravitational potential "g delta-h / c**2" that the optical clocks can now
measure.

changes in g seem to be at 1e-8 level according to [1].
the gravitational redshift is "g delta-h / c**2" or 1e-16 per meter of
height.
if optical clocks were really sensitive to "g" we would be in the same
(horrible) boat as the kibble-balance experimenters who need a map of "g"
in the lab before building the kibble balance and then need to re-measure
that map every now and then... . Instead what optical clock labs need is a
height measurement from the geoid to the experiment (where the cold atoms
are).

"accelerometer" (something that measures "g") is a poor word-choice IMO for
the latest optical clock results...

AW

[1] http://www.leapsecond.com/hsn2006/pendulum-tides-ch3.pdf
Post by John Moran, Scawby Design
Surely, this is nothing new?
I thought standard pendulum clocks were quite good at detecting gravity as well!
_______________________________________________
time-nuts mailing list -- time-***@lists.febo.com
To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Loading...