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Dunash
2002-Apr-02, 07:44 PM
This today from http://www.cyberspaceorbit.com/

"As Earth's rotational momentum begins to decrease, the law of the conservation of energy should cause core
temperatures and subsequent geologic stress to increase in an inversely proportional manner.
http://www.upi.com/view.cfm?StoryID=29032002-101248-3039r

Over the next 6 months, take note if normally accurate time pieces increasingly gain time relative to the
"observed" rate of Earth's spin. As an experiment, you may wish to leave TWO precisely set, independently
ACCURATE time pieces unrecalibrated with any future time-checks to serve as benchmarks. Over the next 6
months, compare "official" time sources (Internet atomic clocks) against these benchmark time pieces to observe
and track if there is a steady increase in the amount of time they gain with each passing month."

Is atomic time changing wrt astronomical time?!

Karl
2002-Apr-02, 07:59 PM
On 2002-04-02 14:44, Dunash wrote:
This today from http://www.cyberspaceorbit.com/



From just above that article:

Planet-X: Time Rolling Up?

Dunash,

Are you now endorsing Planet X hysteria?

Hale_Bopp
2002-Apr-02, 08:58 PM
Let's see...a typical quartz watch is accurate to about 10 to 15 seconds per month. Don't think that is good enough for this experiment.

The atomic clock is synced to the standard by radio, so that's no good either.

Or is this effect supposed to be greather than 1.5 minutes (6 months * 15 seconds/month)?

Maybe I am missing some previous info on this one.

Rob

Karl
2002-Apr-02, 09:22 PM
On 2002-04-02 15:58, Hale_Bopp wrote:

The atomic clock is synced to the standard by radio, so that's no good either.



Rubidium standards show up on eBay once in a while, but I've never been able to convince myself that I really need one. Yet. :-)

aurorae
2002-Apr-02, 09:59 PM
On 2002-04-02 14:44, Dunash wrote:
"As Earth's rotational momentum begins to decrease, the law of the conservation of energy should cause core
temperatures and subsequent geologic stress to increase in an inversely proportional manner.
http://www.upi.com/view.cfm?StoryID=29032002-101248-3039r


Umm, that is a story from UPI about some ground movement under the Three Sisters volcano complex in Oregon.

It's a volcano that hasn't done anything recently (in human terms, in geologic terms it is pretty young), but its a pretty big leap, don't you think, from observing that a single volcano has shifted a little to saying Earth's momentum is changing rapidly?

There are thousands of other volcanos on earth. At any one time some are active, many are not. Are you trying to draw a conclusion that all the volcanoes are going to erupt soon? Seems a pretty tall conclusion from the observation that something is happening under one of them.

And the text of your message was quoted entirely from that other web site. And that web site doesn't appear too concerned about accuracy or logic.

Oh, wait, maybe you could say it was due to the planetary conjuntion! And you could write a book. Oh, wait, that was done before.

<font size=-1>[ This Message was edited by: aurorae on 2002-04-02 17:04 ]</font>

John Kierein
2002-Apr-03, 12:47 PM
The earth does seem to be slowing down slightly. We usually have to add a leap second every year or so to account for this. When working on Iridium, this was important to determining the time a satellite would be in view of a spot on the ground; as the earth rotation rate slowed, the time of arrival would be different. There is a service in France, the Earth Rotation Service, that makes the official time change addition of leap seconds. Some years there are no leap seconds and some years there can be 2. I don't think they've ever had to subtract time. For some reason, I think the leap second has to do with earth rotation, but the year is due to earth revolution around the sun. http://hpiers.obspm.fr/

2002-Apr-03, 02:01 PM
<a name="20020403"> page 20020403 aka 20020403
On 2002-04-02 14:59, Karl wrote: To: 20020403


On 2002-04-02 14:44, Dunash wrote:
This today from http://www.cyberspaceorbit.com/


7:51 A.M. log on to D'bait this 386's time
drift um? maybe relative to the 486 just
to its right or maybe the computer that
hosts this message
I dont know

GrapesOfWrath
2002-Apr-03, 02:29 PM
On 2002-04-03 07:47, John Kierein wrote:
Some years there are no leap seconds and some years there can be 2. I don't think they've ever had to subtract time. For some reason, I think the leap second has to do with earth rotation, but the year is due to earth revolution around the sun.

This old thread (http://www.badastronomy.com/phpBB/viewtopic.php?topic=273&forum=2&start=5) discussed leap seconds, and looked at this NIST page (http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm) list of leap seconds. They've always been inserted on June 30 or December 31, and it says that there will not be one June 2002--which means that come December, it will have been four years that we have not had a leap second. In the thirty years that we've been inserting leap seconds, the next longest period between leap seconds was two and a half years in December of 1987.

aurorae
2002-Apr-03, 03:54 PM
Careful, Grapes, you'll confuse the apocalypic types by using facts.

/phpBB/images/smiles/icon_lol.gif

DStahl
2002-Apr-03, 05:11 PM
Funny! I have always understood that Earth-Moon interaction was gradually slowing the rotation of the Earth, but I envisioned it doing so in a perfectly smooth manner--of course the effect of earthquakes and other terrestrial disturbances would make it a jumpy, uneven slowdown, of course they would.

I believe some German physicists recently finished construction of another ring laser facility capable of measuring tiny variations in the Earth's rotation, a sister to the Canterbury, New Zealand device. It's located in Wetzel (sp?), Germany, almost opposite the Canturbury installation on our Earthly sphere.

To calibrate the device the scientists are asking everyone on Earth to run at top speed to the west for 10 minutes, stop and stand still for 10 minutes, and then turn and run back to the east. The calibration date is to be announced soon. Refreshments will be provided.

Don "I just made that last part up" Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-03 12:14 ]</font>

GrapesOfWrath
2002-Apr-03, 05:19 PM
On 2002-04-03 12:11, DStahl wrote:
Funny! I have always understood that Earth-Moon interaction was gradually slowing the rotation of the Earth, but I envisioned it doing so in a perfectly smooth manner--of course the effect of earthquakes and other terrestrial disturbances would make it a jumpy, uneven slowdown, of course they would.

Yes, it makes sense when you realize it. Still, and this is the exciting part, the variation is ten times what they can account for by all those things you list. They suppose that it is due to massive movements of dense material at the core of the Earth, but no one is sure. There has been some work with the Chandler wobble and meteorological excitation, but I haven't looked into it closely.

John Kierein
2002-Apr-03, 05:24 PM
I think this is the most likely cause. Drag between the earth's core and surface.
http://www.ldeo.columbia.edu/press_releases/song/pr.html

GrapesOfWrath
2002-Apr-03, 08:29 PM
Do you mean the Earth's core and the mantle? That motion at that link is the differential rotation of the inner core, which doesn't touch the mantle.

2002-Apr-07, 12:30 PM
<a name="20020407.6:16"> page 20020407.6:16 aka Time ticks
On 2002-04-03 15:29, GrapesOfWrath wrote: To: 6:16 A.M. PST
2002-04-03 09:01 = 7:51 A.M. +2h -50m
6:16-21 was? Posted: 2002-04-07 08:30
JUMP TO DATA {line after next line}
5:09 A.M. 2-4-09 From: 97209 Posted: 2002-04-07 08:30 5:10 A.M.
http://www.badastronomy.com/phpBB/viewtopic.php?topic=1003&forum=3&8#20020410.3:02
TIME......DATE.........FROM...Extract...........? end of line time..5:11 A.M.Government corruption will always
5: Pacific Standard timebe reported in the past tense.
6: while my Zip 97209 has gon to "DAYLIGHT"
last line time 5:11 A.M.
<font size=-1>[ This Message was edited by: HUb' on 2002-04-08 03:54 ]</font>

<font size=-1>[ This Message was edited by: HUb' on 2002-04-09 07:21 ]</font>

<font size=-1>[ This Message was edited by: HUb' on 2002-04-13 08:28 ]</font>

Donnie B.
2002-Apr-07, 03:11 PM
Hub,

Don't rely on the clock in your PC. They are not very accurate, and their drift isn't even predictable. My system at work can lose or gain minutes per day!

My home system is better, but still can gain or lose a few seconds a day.

My reference is NIST time. You can download an app that will access the NIST atomic-clock-based time and reset your PC clock to match; I do that here every few days.

The application I use is "About Time". There are lots of others. They all will set your PC clock to within a second of reference time, which is good enough for most uses but not for any scientific work.

If you're serious about doing absolute-time based studies, you can get WWV receivers that can output an accurate reference time on demand.

2002-Apr-08, 08:05 AM
<a name="20020408.1:47"> page 20020408.1:47 aka 11:11, Donnie B Good
On 2002-04-07 11:11, Donnie B. wrote: To:
Hub, Listening to {in the `90's} the voice comming
out of a Mac computer .. at PSU i could recognize
Maryland Monrow instantly, when the two kids
who were running the equipment, and changed
the voice uttering those lines of text to W.C. Fields
it cracked up everone in that {un you know}[SOMBER]
computer lab. really kids were almost falling out of
their chairs with laughter and myrh.. Neadless to say
"THOSE COMPUTER's" did not last verey long,
"in an instiution of higher .edu" and by terms in
THEY were "OUT OF THERE" ahh the good old times..
__So sure if you can upload { or explain to me how }
TWO different "ABSOLUTE" time standards i'd try the test myself.. HUb'

2002-Apr-09, 11:31 AM
[quote]
On 2002-04-08 04:05, HUb' wrote:
1: IT WOULD APPEAR
2: that when an entrys EDITED
3: that THAT entry retains the
4: ORIGIONAL post time
5: So theres no NEW time stamp to
6: compare to so my efforts
7: FEWtile {oh my}
8:
9:
anyway i'll not give up easily
and will endevor som way to do a cross check
--below may be a time test--and maybe not2
http://tycho.usno.navy.mil/
maybe that will link thru
and maybe it will NOT
now all i need's just one more time tick & [Can_Do]

dapted
2002-Apr-11, 05:23 AM
I have been personaly responsible for keeping of atomic clocks in years past. The rubidium ones were not as reliable as the cesium ones. We used them to calibrate loran transmitters and worked in conjunction with other standards stations to keep up the National Bureau of Standards. Lots of fun things need to know what time it is down to 10^-16 seconds. But the rub came when we took multiple clocks on one aircraft flying around the earth east to west, while another cluster flew around west to east. Not a big time change, but enough difference to prove (sort of) the laws of causality and good old Einstein's Relativity.

The rub comes when we approach the speed of light even fractionally that time (for the moving object) slows down relative to us earthlings. The contrary must also be considered, if we find a way to get to zero speed, does time speed up or slow doem for us on earth? Can we make something age prematurely by putting it closer to zero speed. How do we measure zero speed? Against what? Since rotational speed around the center of the earth can cause time to be gained or lost, relative to sitting still, how can anybody claim that time is a constant? Won't it depend on which way your clocks are traveling and at what speed?

So the point of this? Is the earth rotational speed changing, or is the decay rate of cesium changing? Or is the clock used to measure it simply located someplace that doesn't move so fast around the axis of the earth? Say near a pole?

The more answers I get, the more questions I got.

Dan

WHarris
2002-Apr-11, 10:15 AM
Here's another link, from USNO's Earth Orientation Dept.:
What is a Leap Second? (http://maia.usno.navy.mil/eo/leapsec.html)

GrapesOfWrath
2002-Apr-11, 10:41 AM
On 2002-04-11 01:23, dapted wrote:
Or is the clock used to measure it simply located someplace that doesn't move so fast around the axis of the earth? Say near a pole?

The more answers I get, the more questions I got.

And that is an interesting question. The Straight Dope answered the question "Do you age more quickly at the pole than than equator due to relativity?" (http://www.straightdope.com/classics/a4_183.html). Short answer? No.

GrapesOfWrath
2002-Dec-09, 04:54 PM
On 2002-04-03 09:29, GrapesOfWrath wrote:
This old thread (http://www.badastronomy.com/phpBB/viewtopic.php?topic=273&forum=2&start=5) discussed leap seconds, and looked at this NIST page (http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm) list of leap seconds. They've always been inserted on June 30 or December 31, and it says that there will not be one June 2002--which means that come December, it will have been four years that we have not had a leap second. In the thirty years that we've been inserting leap seconds, the next longest period between leap seconds was two and a half years in December of 1987.

Of course it now says that there will not be a leap second this month, so there probably won't have been one for four and a half years, come next June. It has taken us over a year to lose .2 second in UT1-UTC, but we are pretty much where we were four years ago just before the last leap second was inserted, so maybe we'll see a leap second in June.

2002-Dec-10, 03:27 PM
<a name="2-12-10.clk"> page= 2-12-10.clk aka clocks
On 2002-12-09 11:54, GrapesOfWrath wrote:
1 of course? i hav my own words for clocks
and i use 5 clocks (C1,C2,C3,C4, &C5)
3 the comparison between D3=C3 where Earth Spin
and Earths orbit are the main topics
<a name="2-12-10.Lnk"> line= 2-12-10.Lnk
http://www.badastronomy.com/phpBB/viewtopic.php?topic=2651&forum=3#20021105.TD aka 2003 TIME DRIFT
7 & D4=C2 where Electron Spin : orbit ratios matter
{call it atomic Clocks if you like} are all 5 changing {see follow up post}

<font size=-1>[ This Message was edited by: HUb' on 2002-12-10 10:46 ]</font>

2002-Dec-10, 03:44 PM
<a name="2-12-10.5Ck"> page= 2-12-10.5Ck aka Five Clocks

C1/D5 ????????????? { o:s_?. } 2e??:1
theres not much know about this
C2/D4 Electron Orbit/spin ratios {o:s_El} 2:1
possibly spin locked(steady) orbits slowing (?red shift?)
C3/D3 Earth orbit/spin ratio { o:s_Ea } 1:365
currently spin slowing ? XfasterX Slower than orbit slowly Slowing dS/dO=1.?+
C4/D2 Sun orbit/spin ratio { o:s_Su } ?:24e7
split | outer stars slowing inner speading up?
C5/D1 Galaxy orbit/spin ratio ( o:s_Ga } 1:Big?
? What do Galaxies orbit? Each other ? Center of Uni ? {i donno}
Note If C1/D5 non existant then assume C6/D0 may? {beyound Uni}

<font size=-1>[ This Message was edited by: HUb' on 2002-12-11 19:14 ]</font>

Mainframes
2002-Dec-11, 10:42 AM
Correct me if i'm wrong, but I always thought that the earth was slowing down (albeit at a very slow rate) due to interactions with the moon.

The underlying principle being the conservation of momentum and angular momentum, and the fact the moon is gradually gaining momentum from the earth causing the earth to slow down until it is tidally locked to the moon. Much like the moon is to earth already.

Donnie B.
2002-Dec-11, 02:48 PM
Mainframes, you're correct. However, the rate of that slowdown is not constant. The Earth-Moon interactions are complex, with a lot of variables coming into play (such as the shape and position of the continents). So sometimes the deceleration is more pronounced than others. Hence the irregular application of leap seconds.

2002-Dec-13, 05:22 PM
<a name="2-12-13.dD"> page= 2-12-13.dD aka dD
On 2002-12-11 09:48, Donnie B. wrote:
1 I tried2 access the lunar Distance data
never could understand the Laser numbers
3 My approach to the Distance question would be
different {IF I COULD} i would use
<a name="2-12-13.Lnk"> line= 2-12-13.Lnk
http://www.badastronomy.com/phpBB/viewtopic.php?topic=311&forum=3
7 GeoSyncronus Satalite downLINKs
not the Graphics But THE RF carrier itself (see next post)

<font size=-1>[ This Message was edited by: HUb' on 2002-12-13 12:26 ]</font>

2002-Dec-13, 05:36 PM
December 13, 2002 9:34 A.M.
<a name="2-12-13.rfD"> page= 2-12-13.rfD aka Radio Frequency Doppler
the THeory of Distance {based upon RF doppler}
1 Goes line this
Earth)=====0 Ge0syncrOnus satalite
a reciever/recorders set up on Earth
to recieve a downlink Radio Frequency signal
from a GeoSyncrnous satalite (no I don't know which 1)
anyone will do? {thats my guess}
anyway as the moon tugs the satalite away from
Earth as it passes over head at the Satalites Longitude
the RF carrier from the radio should shift
to a lower frequency ..thus there should be a STANDARD
shift up and down / phase locked to the Moon
of the RF doppler shift.. Once THERE IS A STANDARD plot
then veriation's from the standard should be found { as Sky lab passes benighth?} etc?

2002-Dec-14, 02:01 PM
<a name="2-12-14.mh3"> page= 2-12-14.mh3 aka 5:59 A.M. Mh 3
On 2002-12-13 12:36, HUb' wrote: To? HUb'
1 yeah caluclate the doppler shift
differential on the approaching edge
3 and on the receeding edge of earth?

<a name="2-12-14.LkB"> line= 2-12-14.LkB
http://www.badastronomy.com/phpBB/viewtopic.php?topic=3187&forum=3&5
7
for a geostationary it would seam? at first
glance that /o there would be no shift
on eiithor side East or West
---------------------------
in terms of absolutes {reluctant Line of reason?}
it may be that the exact wave length WEST
would not exactly equal the wavelenght East?
========= I dont really know .. its of interest
and Iwill work on it {see how many years it takes}
for my 1st approximation to be posted {Math hours OVER}.

GrapesOfWrath
2002-Dec-17, 10:07 AM
On 2002-12-14 09:01, HUb' wrote:
reluctant Line of reason?
You're dragging reason into this?

I have one question, what object are you asking about here: "as Sky lab passes benighth?"

Tim Thompson
2002-Dec-18, 11:13 PM
Mainframes: ... I always thought that the earth was slowing down (albeit at a very slow rate) due to interactions with the moon.

Donnie B: Mainframes, you're correct. However, the rate of that slowdown is not constant.

Indeed not. I have written a FAQ file for the Talk.Origins archive which discusses the tidal interaction between Earth & the moon at some length: "The Recession of the Moon and the Age of the Earth-Moon System (http://www.talkorigins.org/faqs/moonrec.html)". Although written to counter creationist claims of a "young" Earth-moon system, the discussion is still much in line with the questions here.

At the moment, the rate of slowdown is about 0.0015 sec/day/century, meaning that every 100 years, the "24 hour day" gets 0.0015 seconds longer. It is an abnormally high rate of change, due to the fact that the size of Earth's ocean basin's is about the same as the wavelength of the lunar tidal wave, so they resonate and accelerate the slowdown. Once the continents drift around a bit, the slowdown rate will decrease rather noticably.

Some of the energy lost to Earth's spin is transferred to the moon, and it moves away from Earth as it gains energy. The rest of the energy is lost to thing like dissipation as heat in Earth's mantle. Today, most of the energy goes to the moon, but when the Earth was infantile, most of it went into dissipation.

As for the leapseconds, see the "What is a Leap Second? (http://maia.usno.navy.mil/eo/leapsec.html)" page posted by WHarris. The leap second is not really related to Earth's slowdown, but rather to the fact that one UTC second and one TAI second are not the same, so there is a "beat frequency" between them. Out of an arbitrary desire to keep both clock's within 0.9 seconds of each other, the leap second is periodically added. So its sole function is to make two clocks, which run at differing rates, read the same time.

The Chandler wobble is probably due to exchange of angular momentum between the atmosphere, oceans, and solid Earth, though noone has proven this as far as I know. Friction at the core-mantle boundary is certainly responsible for the microsecond sized "jerks" in rotation speed, that happen essentially on a daily basis; see Excess to 86400s of the duration of the days, combined GPS solution, 1995-1997 (http://www.iers.org/iers/earth/rotation/ut1lod/figure2.html). The referenced diagram shows sharp, sub-millisecond sized "jerks" in the length of day, as well as a millisecond sized seasonal signature, which is certainly caused by an exchange of momentum between the atmosphere (mostly) and oceans and solid Earth.

But don't be too surprised if nothing "spectacular" happens in the next 6 months, as Dunash hints. The average heat energy coming up through the Earth's surface at the moment is about 0.0615 Watts/m^2, as compared to the top of atmosphere solar constant of about 1360 Watts/m^2. So if the Earth wants to compete with the sun for heat at the surface, the "jerk" might just knock you over.

And just to keep things astronomical, I will point out that the Chandler wobble was discovered by astronomers. Astronomers practicing precision astrometry discovered that their own station latitudes were not constant, which had been thought impossible. The International Latitude Service, established in 1899, was the response to the discovery that latitude could vary with time; see, for instance, "Historical Development of Earth Rotation Knowledge (http://www.geo.tudelft.nl/fmr/research/EarthRotHistory.html)". So far as I know, the International Latitude Service no longer exists, its functions absorbed by the International Earth Rotation Service (http://www.iers.org/), represented in the U.S. by the Earth orientation Department (http://maia.usno.navy.mil/eo/) of the U.S. Naval Observatory (http://www.usno.navy.mil/) (it's still done by astronomers).

Cheers.

Prince
2002-Dec-18, 11:32 PM
It should be called the IURS: the International Universe Rotation Service! In Messianic times to come CNN, the BBC, Fox etc will have a different musical introduction to their news: not a rotating Earth, but a stationary one, with a depiction of the cosmos going round it! The populace will feel much better knowing that they are physically, as well as spiritually at the center of the Creator's attentions!




<font size=-1>[ This Message was edited by: Prince on 2002-12-18 19:01 ]</font>

GrapesOfWrath
2002-Dec-19, 01:53 PM
On 2002-12-18 18:13, Tim Thompson wrote:
As for the leapseconds, see the "What is a Leap Second? (http://maia.usno.navy.mil/eo/leapsec.html)" page posted by WHarris. The leap second is not really related to Earth's slowdown, but rather to the fact that one UTC second and one TAI second are not the same, so there is a "beat frequency" between them. Out of an arbitrary desire to keep both clock's within 0.9 seconds of each other, the leap second is periodically added. So its sole function is to make two clocks, which run at differing rates, read the same time.
I agree with most of what you said there, Tim, but I'm not sure of these. The UTC second and the TAI second are the same length, but the leap seconds are added to UTC so that UTC matches the Earth's rotation. The mean solar day is now approx. 86400.002 seconds, which would require a leap second about every 500 days. It is the UTC day and the TAI day that are of different lengths.

Leap seconds are added because of that discrepancy, but the reason that there is a discrepancy in the first place is that the second was defined as one 86400th of the mean solar day in the year 1900. Since then, the Earth has slowed down--so there is a relationship between the slowing of the Earth, and leap seconds, but it is not direct. For instance, I've mentioned before, we haven't had a leap second for nearly four years, so the Earth has sped up considerably--but we haven't come close to needing a negative leap second.

2002-Dec-19, 05:14 PM
<a name="2-12-19.SD?"> page= 2-12-19.SD? aka Second Difference?
On 2002-12-19 08:53, GrapesOfWrath wrote:
1
I noticed my 486/2003 time drift has suddenly gone from
3 one second per day to two?
I also see the dV/dT for Cassini being anamoplous?
<a name="2-12-19.Li3"> line= 2-12-19.Li3
?link to cassini?
7 makes me wonder?
?link to time standard?

GrapesOfWrath
2003-Jan-29, 02:30 PM
On 2002-12-09 11:54, GrapesOfWrath wrote (http://www.badastronomy.com/phpBB/viewtopic.php?mode=viewtopic&topic=928&forum=1&start=20):
maybe we'll see a leap second in June.

Nope. According to the NIST webpage (http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm), they are not expecting to add a leap second in June ("Note: No positive leap second will be introduced at the end of June 2003.")

If it is December 2003 before we add a leap second, it will have been a five year gap, the longest previous gap was 2 1/2 years, from 6/1985 to 12/1987, which was followed and preceded by two two-year gaps. Other than those, they've been 1 1/2 years or less.

I think that's interesting.

2003-Jan-29, 03:15 PM
<a name="3-1-29.YyW"> page= 3-1-29.YyW aka YEAH, yaeh; What?
On 2003-01-29 09:30, GrapesOfWrath wrote:
.1 As I recall .. {you said} YOU HAVE Mathametica ..
2: when I ask Streeter (last week) about
3.. Mathametica {he told me NO}
I ask Why.. he said the price was 20k vs 10
for the other 2 .. Told me to learn Maple
--------------------------------------------
anyway I was glad that "Tim" explained the rate
question well {a link to the plot woud help}
Just i dont have time just now to comprehend it all
So My Question for you {Math} what University(s) involved if any?

GrapesOfWrath
2003-Jan-29, 03:31 PM
On 2003-01-29 10:15, HUb' wrote:
So My Question for you {Math} what University(s) involved if any?

I have an old version of Mathematica, but it serves my purposes. I'm not at any university right now. Is that what you meant?

For the most part, if you just type in an expression, the software will evaluate it. For instance, 52 7 24 60 60 will give you how many seconds in 52 weeks. Plot[Sin[x],{x,-2 Pi, 2 Pi}] will give you a nice sine curve from negative 2 pi to positive 2 pi.

2003-Jan-30, 02:54 AM
<a name="JD2452669"> page JD2452669 aka JD2452669
On 2003-01-29 10:31, GrapesOfWrath wrote:

On 2003-01-29 10:15, HUb' wrote:

Just checking..7:04 P.M. PST

2003-Mar-13, 06:53 AM
<a name="JD2452711.AP2"> page JD2452711.AP2 aka another PUSH 2
On 2002-04-02 14:44, Dunash wrote:
This today from http://www.cyberspaceorbit.com/



http://www.upi.com/view.cfm?StoryID=29032002-101248-3039r

2003-Mar-13, 07:35 AM
<a name="JD2452711.pdD"> page JD2452711.pdD aka planedD O
On 2003-01-29 09:30, GrapesOfWrath wrote: To! HUb'
[quote]
On 2002-12-09 11:54, GrapesOfWrath wrote (http://www.badastronomy.com/phpBB/viewtopic.php?mode=viewtopic&topic=928&forum=1&start=20):
maybe we'll see a leap second in June.

Nope. According to the NIST webpage (http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm), they are not expecting to add a leap second in June ("Note: No positive leap second will be introduced at the end of June 2003.")
March 12, 2003 3-3-12 11:39 P.M. I am JUST NOW wondering
if they'LL release the next version of OSx for Macs at
the same moment? {hmm?} My current guess is the PLANED`d O
calls for Quicktime towork on Macs at that time
and then Faster than time to be implemented back to IBM/comPATables Fall term04 thus I/M/I/M 4eve the new2party 0

JS Princeton
2003-Mar-13, 07:35 AM
On 2002-12-18 18:32, Prince wrote:
It should be called the IURS: the International Universe Rotation Service! In Messianic times to come CNN, the BBC, Fox etc will have a different musical introduction to their news: not a rotating Earth, but a stationary one, with a depiction of the cosmos going round it! The populace will feel much better knowing that they are physically, as well as spiritually at the center of the Creator's attentions!


This post is a parody of itself. It's scary that Prince actually believes such things. Oh well, there's a sucker born every minute!

kilopi
2003-Aug-23, 09:52 AM
On 2002-04-03 09:29, GrapesOfWrath wrote:
This old thread (http://www.badastronomy.com/phpBB/viewtopic.php?topic=273&amp;forum=2&amp;start=5) discussed leap seconds, and looked at this NIST page (http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm) list of leap seconds. They've always been inserted on June 30 or December 31, and it says that there will not be one June 2002--which means that come December, it will have been four years that we have not had a leap second. In the thirty years that we've been inserting leap seconds, the next longest period between leap seconds was two and a half years in December of 1987.

maybe we'll see a leap second in June.
Not only did we now see a leap second in June, the NIST page now reports that there will be no leap second in December! If the next one is June 2004--and that may be a big if at this point--it will have been 5 1/2 years.

swansont
2003-Sep-13, 01:07 AM
Not only did we now see a leap second in June, the NIST page now reports that there will be no leap second in December! If the next one is June 2004--and that may be a big if at this point--it will have been 5 1/2 years.

Actually, if you look at the excess length of day at the USNO Earth Orientation site (http://maia.usno.navy.mil/eo/whatiseop.html) you'll see that the earth's rotation has been speeding up as of late, and the ELOD is actually currently (or at least recently) negative.

There's a chance we'll have to remove a leap second at some point, should this trend continue.

kilopi
2003-Sep-13, 09:15 AM
Actually, if you look at the excess length of day at the USNO Earth Orientation site (http://maia.usno.navy.mil/eo/whatiseop.html) you'll see that the earth's rotation has been speeding up as of late, and the ELOD is actually currently (or at least recently) negative.
It's been speeding up a lot (http://www.badastronomy.com/phpBB/viewtopic.php?p=136580&amp;highlight=leap#136580). The slowing due to tidal friction is said to be about 2 msec per century. Since our reference day is from 1900, our reference day should now be 2 msec too short. Even if the Earth didn't slow down at all anymore, we'd need a leap second every 500 days. That we haven't had a leap second in five years means that not only have we sped up, we've sped up enough to erase 100 years of slowing down.


There's a chance we'll have to remove a leap second at some point, should this trend continue.
That's allowed. :)

swansont
2003-Sep-23, 02:18 PM
Actually, if you look at the excess length of day at the USNO Earth Orientation site (http://maia.usno.navy.mil/eo/whatiseop.html) you'll see that the earth's rotation has been speeding up as of late, and the ELOD is actually currently (or at least recently) negative.
It's been speeding up a lot (http://www.badastronomy.com/phpBB/viewtopic.php?p=136580&amp;highlight=leap#136580). The slowing due to tidal friction is said to be about 2 msec per century. Since our reference day is from 1900, our reference day should now be 2 msec too short. Even if the Earth didn't slow down at all anymore, we'd need a leap second every 500 days. That we haven't had a leap second in five years means that not only have we sped up, we've sped up enough to erase 100 years of slowing down.

I checked into this further. The ELOD is after the tidal term is taken out, so in fact we aren't speeding up nearly as much as all that. If you look at UT1-UTC, it's decreased from about 0.7 s at the time of the last leap second insertion to about -0.35 sec recently. So the average slowdown is ~0.5 ms/day recently, vs ~1.5 over the long-term. We haven't actually erased all of it.

Though it's mandated that the difference never exceed 0.9 s, they don't wait that long to insert the leap seconds. Most of the last several occurred when the difference was about -0.5s, with a clear trend toward slowing. The last one was at -0.3s, so there was further to go. That, and the reduced rate accounts for the longer time to insert the next one.

I gleaned from a recent discussion that one term that may be contributing to a speedup is the refilling of groundwater, depleted from recent droughts in North America (and possibly elsewhere) shifting some mass away from the equator. Also, while the polar caps are getting smaller, there's apparently a rebounding of the mantle (less weight on top of it) which ends up decreasing the oblateness of the earth, and this actually dominates or at least cancels the mass distribution term. (All of this last paragraph is a summary, limited by my lack of expertise in Earth Orientation matters)

kilopi
2003-Sep-23, 03:49 PM
I checked into this further. The ELOD is after the tidal term is taken out, so in fact we aren't speeding up nearly as much as all that. If you look at UT1-UTC, it's decreased from about 0.7 s at the time of the last leap second insertion to about -0.35 sec recently. So the average slowdown is ~0.5 ms/day recently, vs ~1.5 over the long-term. We haven't actually erased all of it.
The rate of UT1-UTC is not a measure of the slowing down, the rate of the rate is how much Earth is slowing down. If the rate of change of UT1-UTC were constant, the Earth would not be slowing down at all.

The average slowdown of the Earth's daily rotation, over the long term, was 1.5-2.5 ms per century.


Though it's mandated that the difference never exceed 0.9 s, they don't wait that long to insert the leap seconds. Most of the last several occurred when the difference was about -0.5s, with a clear trend toward slowing. The last one was at -0.3s, so there was further to go. That, and the reduced rate accounts for the longer time to insert the next one.
At a rate of 2 ms per day, the additional .2s could have been covered in a 100 days. From Jan. 1 1972 to Jan. 1 1999, about 27 years, there were 22 leap seconds, so the rate of UT1-UTC was about 2.2 ms per day for that period (for the first ten years, the rate looked to be about 3.0 ms per day, so it slowed some over the next twenty years). That's consonant with the fact that our time reference is from a hundred years ago--the difference has built up in the hundred years to about 2ms per day. As you point out, in the last five years, though, the difference has changed to about .5 ms per day.

If the rate of the rate of UT1-UTC were to stay the same as it averaged over the century, the rate of slowing would be the 2ms/day/century. In other words, in five years, the rate of UT1-UTC would go from 2.2ms per day to 2.3ms per day (an additional one twentieth of the full century value). Since it has gone from 2.2 to 0.5, a decrease of 1.7, that indicates a speeding up 18 times the historical slowing down (the ratio of (2.3-0.5)/(2.3-2.2)). At that rate, it would take just one more year to erase the entire tidal slowing of the past century. In ten years, if the rate were to continue (which I imagine is not very probable), not only would we have negative leap seconds, we'd have negative leap seconds every six months. It would be international front page news long before that.

It has not been unusual to see changes a whole order of magnitude greater than the tidal slowing. They have been common. What is unusual is that in the past they have been more or less random (yet unexplained!) within a given year, and off-setting--the recent figures in the trend have been consistent over three or four or five years.

swansont
2003-Sep-23, 06:11 PM
The average slowdown of the Earth's daily rotation, over the long term, was 1.5-2.5 ms per century.

Just to clarify -the units are ms per day per century, and the value is actually closer to 1 - 1.5. And the slowdown I was referring to was timing, not earth rotation which are, as you noted, different (as clock differences do not require a rotation rate change)



At a rate of 2 ms per day, the additional .2s could have been covered in a 100 days. From Jan. 1 1972 to Jan. 1 1999, about 27 years, there were 22 leap seconds, so the rate of UT1-UTC was about 2.2 ms per day for that period (for the first ten years, the rate looked to be about 3.0 ms per day, so it slowed some over the next twenty years). That's consonant with the fact that our time reference is from a hundred years ago--the difference has built up in the hundred years to about 2ms per day. As you point out, in the last five years, though, the difference has changed to about .5 ms per day.


Actually the time reference is a little more complicated - an average day was 86400 sec in ~1820, not 1900. Click here (http://tycho.usno.navy.mil/leapsec.html)

kilopi
2003-Sep-23, 06:47 PM
an average day was 86400 sec in ~1820, not 1900. Click here (http://tycho.usno.navy.mil/leapsec.html)
That's an interesting link, thank you. (Hey, isn't that Dick Cheney's house?) It contradicts another link at the same site (http://maia.usno.navy.mil/eo/leapsec.html), but I like yours. 1820 is inferred of course and the recent speeding up suggests a large error bar, but using that date implies that the recent speeding up is much more than 18 times as great as the tidal slowing.

A Thousand Pardons
2004-Sep-20, 09:47 AM
On 2002-04-03 09:29, GrapesOfWrath wrote:
This old thread (http://www.badastronomy.com/phpBB/viewtopic.php?topic=273&amp;forum=2&amp;start=5) discussed leap seconds, and looked at this NIST page (http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm) list of leap seconds. They've always been inserted on June 30 or December 31, and it says that there will not be one June 2002--which means that come December, it will have been four years that we have not had a leap second. In the thirty years that we've been inserting leap seconds, the next longest period between leap seconds was two and a half years in December of 1987.

maybe we'll see a leap second in June.
Not only did we now see a leap second in June, the NIST page now reports that there will be no leap second in December! If the next one is June 2004--and that may be a big if at this point--it will have been 5 1/2 years.
And no leap seconds this December either, so it will have been 6 1/2 years, in June.

Kesh
2004-Sep-20, 11:29 PM
*burns A Thousand Pardons at the stake for being a thread necromancer* ;)

Gsquare
2004-Sep-21, 01:19 AM
....
To calibrate the device the scientists are asking everyone on Earth to run at top speed to the west for 10 minutes, stop and stand still for 10 minutes, and then turn and run back to the east. The calibration date is to be announced soon. Refreshments will be provided.



It will never work. [-( Those located directly on the shore of the West coast will be forced to swim west for the first ten minutes, tread water for the next 10 minute, and then swim back East for ten minutes; many will drown, screwing up the whole calibration. :P

G^2

--"I used to think I was indecisive, but now I'm not so sure".--

swansont
2004-Sep-24, 11:21 AM
And no leap seconds this December either, so it will have been 6 1/2 years, in June.

Yes, but UT1-UTC now stands at about -.46 sec (and slowly getting larger in magnitude) and they have to change it before it gets to -0.9. They usually add a leap second when it gets close to -0.5 sec. The predicitions in Bulletin A of the IERS have the difference changing direction within a year (peaking at -.57 sec), so I'm guessing they don't want to add a leap second until they have to, if there's the chance they'll just have to remove it later.