Hi
BIH
Bob
On May 11, 2012, at 5:49 PM, Peter Monta wrote:
>> Everyone should take ten seconds and look at this animated GIF:
>> http://leapsecond.com/pages/ut/ut-ani-v2.gif
>
> Very nice. I guess a comparable plot with ephemeris time would be a
> lot noisier and sparser, something like the g
> Everyone should take ten seconds and look at this animated GIF:
> http://leapsecond.com/pages/ut/ut-ani-v2.gif
Very nice. I guess a comparable plot with ephemeris time would be a
lot noisier and sparser, something like the graphs in the Markowitz
1988 paper.
I wonder if there's some sort of IE
IMO, that would be a disaster for all areas of physics and engineering,
except for possibly some aspects of astronomy.
When they 'redefined' the Volt some years ago it was a goat rodeo.
-John
===
> So what you are saying is every 30 years select a new leap CS reference.
> Dispe
So what you are saying is every 30 years select a new leap CS reference.
Dispense with everything in between.
On Fri, May 11, 2012 at 2:21 PM, Tom Van Baak wrote:
> > Are there better estimates of the ET second nowadays (relative to the
> > SI second)? It would be interesting to know what the c
> Are there better estimates of the ET second nowadays (relative to the
> SI second)? It would be interesting to know what the cesium frequency
> "should have been" if much better estimates of the ephemeris-time
> second were available at the time.
Hi Peter,
Everyone should take ten seconds and
OK I have learned a lot and absolutely fantastic news.
No matter what my aged CS says I can claim its accurate now. Its simply the
world has not caught up to or slowed down to it.
Regards
Paul
On Fri, May 11, 2012 at 2:30 AM, mike cook wrote:
> Le 11/05/2012 07:14, Peter Monta a écrit :
>
> Are
Le 11/05/2012 07:14, Peter Monta a écrit :
Are there better estimates of the ET second nowadays (relative to the
SI second)? It would be interesting to know what the cesium frequency
"should have been" if much better estimates of the ephemeris-time
second were available at the time. One would t
Are there better estimates of the ET second nowadays (relative to the
SI second)? It would be interesting to know what the cesium frequency
"should have been" if much better estimates of the ephemeris-time
second were available at the time. One would think that with all the
solar-system data JPL
> Thanks, all ...this thread has helped me a lot.
>
> It reinforces my beliefs of what a 'second' is ...what we were taught from
> day 1 in school:
>
> One solar day/86,400 (A 'solar' day being an earth solar day)
Hi Don,
This was true until the 1960's. Hopefully the school curriculum has been
On 5/9/12 4:27 PM, Charles P. Steinmetz wrote:
Don wrote:
It's interesting to note (to ask?): When did someone get smart enough to
start measuring 1/86 thousandth of a day
That is generally considered to be the 10th/11th century Persian Muslim
mathematician and astronomer, Abu al-Rayhan Muham
"Connections" is a wonderful series, as is "The Day The Universe Changed".
Thanks for the YouTube link.
-John
> James Burke did a whole episode of Connections on that subject:
>
> https://www.youtube.com/playlist?list=PL777ACC303F62C744
>
> The oldest example of an automated ph
Don wrote:
It's interesting to note (to ask?): When did someone get smart enough to
start measuring 1/86 thousandth of a day
That is generally considered to be the 10th/11th century Persian
Muslim mathematician and astronomer, Abu al-Rayhan Muhammad ibn Ahmad
al-Biruni (a.k.a. Alberonius and
James Burke did a whole episode of Connections on that subject:
https://www.youtube.com/playlist?list=PL777ACC303F62C744
The oldest example of an automated phase locked loop I have heard of
was used for calibrating newly built pendulum clocks to a master
pendulum clock.
On Wed, 9 May 2012 17:45:
precise time and frequency measurement
Subject: Re: [time-nuts] Why 9,192,631,770 ??
This issue came up when I was involved in SETI work. One big question was
"How do you know what frequency to listen at?"
Any earth-centric system is essentially arbitrary. There is nothing
'
This issue came up when I was involved in SETI work. One big question was
"How do you know what frequency to listen at?"
Any earth-centric system is essentially arbitrary. There is nothing
'universal' about the Meter, Kilogram, or Second. (or any of their
equivalents in other systems of units).
A
>It is interesting that the leap seconds correction is always a positive
>number.
But less so now than 40 years ago according to:
http://en.wikipedia.org/wiki/Leap_second
So does that mean the earth is speeding up? Maybe the cause is all the DARK
ENERGY out there speeding everything up :)
> Thanks downloaded the paper. I assume the hyper fine transition happened to
> be the one nearest that frequency? You can tune to either side of the peak
> and get a lock on the next transition.
> Regards
> Paul.
Hi Paul,
The definition is the second specifies which hyperfine transition to use;
In message , "Eric Lemmon" wri
tes:
>No, leap seconds have to do with the gradual slowing of the Earth's
>rotation, and nothing to do with Cesium.
Not quite true.
When they decided the 9,192,631,770 they did so with astronomical
observations which were half a century old. If they had used a
mor
On Tue, May 08, 2012 at 09:28:33PM -0400, David McGaw wrote:
> It is my understanding that they actually got it a bit wrong, which
> is why we seem to have a lot of leap seconds.
The atom is a much better timekeeper than the Earth. They
could have chosen differently for convenience, but t
PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Why 9,192,631,770 ??
It is my understanding that they actually got it a bit wrong, which is
why we seem to have a lot of leap seconds.
David
On 5/8/12 9:19 PM, paul swed wrote:
> Thanks downloaded the paper.
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Jerry Mulchin
Sent: 09 May 2012 01:56
To: j...@quikus.com; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Why 9,192,631,770 ??
It is interesting that the leap
Sent: 09 May 2012 01:56
> To: j...@quikus.com; Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Why 9,192,631,770 ??
>
> >It is interesting that the leap seconds correction is always a positive
> number.
>
> Jerry
>
>
>
com; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Why 9,192,631,770 ??
>It is interesting that the leap seconds correction is always a positive number.
Jerry
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Yes, but eventually the time must be corrected with leap seconds because of all
the
randomness that accumulates. It is interesting that the leap seconds correction
is
always a positive number. We never seem to gain time that I'm aware of. argh
Jerry
At 05:35 PM 5/8/2012, you wrote:
>Becaus
Because the length of the second is essentially arbitrary. There is
nothing 'fundamental' or 'universal' about it. It is essentially derived
from the average rotational period of the earth, which is a random number.
When the number of cycles was defined, they picked the nearest whole
number to an
Who decided 9,192,631,770 cycles of 'light' constitute one second? I don't
mean who the person was, or which company or institution or when.
I ask, why not ...771 cycles ...or ...669 cycles
Hi Don,
It was the result of 4 astronomical measurements made over several years.
9,192,631,76
I've gotten myself confused ...easily done when you're not a physicist (just
a lowly EE.) :-)
I am studying cesium clock design and trying to learn how these complex
instruments actually work. I seem to be getting the understanding on the
'workings' of the clock ...the tube, the counters, discip
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