I don't think I can provide any evidence to support this assertion,
but I'm quite sure I don't see it very often. Of course it depends
a lot on what I'm doing. The thing is, most often when I notice
the time, it is because I deliberately look to see the time. I think,
"What time is it?" and then I turn my head and eyes so that I can
see it.

The day before yesterday, though, when I was writing a reply
to the question about circles, I wanted to check that the Sun
is a circle, so I went to the south side of the building and was
shocked at how low and how far west the Sun was. WAY too
low and too far west for 1:10 PM. I came back, checked my
clock, and then checked the Sun again. Then I checked the
clock on the computer. 3:20. My wall clock battery died two
hours and ten minutes earlier. A while later I noted that I
should take something out of the oven in five minutes, at 1:15.
That sounded a bit too familiar though and nothing got burned.

Anyway. I had a grocery bill total $111.11 a couple years ago.
And a month or two ago I noticed that I had been online for
four hours, fourty-four minutes and fourty-three seconds.
Almost.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Then there's my favorite: pi oclock - 3:14.

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Oh great, now I'll start seeing that all time..............


-Richard

This one get me too, especially on Pi Day, March 14th... but I guess then it should be 1:59

Hmmmm. Not according to Jean Meeus' 3000-year tables: 11:12:43 is the appointed second.

Grant Hutchison

I just came back to this thread, read the new posts, then looked
down at the clock. It changed from 11:13 to 11:14 as I looked.
Missed it by that much.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

I've been using a system of putting compacted dates in filenames
since the days of DOS. December 02 is carbon dioxide day: C02.

How far off topic can I get? Farther, farther!

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Grant,

The US Naval Observatory says 11:11AM: (Edit: this is AM, not PM, actually!)

http://aa.usno.navy.mil/data/docs/EarthSeasons.html

They don't give it to the second there, however.

So there is some slight difference in whatever formula and current position data they are using, maybe some slight difference in the *timekeeping* standard itself. One minute is not much to worry about with this stuff, but I do wonder what the difference is.

-Richard

Ah, you're right, it's my mistake.
Meeus is using Dynamical Time, which is rather more than a minute ahead of UT. By 2012 the difference will be something like 78 seconds, which accounts for the USNO's figure, and also for their coy avoidance of exact seconds: they can't know exactly by how much DT and UT will differ until after the event.

Grant Hutchison

Ah, so.

Hee, hee. I remember you've mentioned that GR calculations sort of waft over your head. Well, this kind of stuff does the same for me. When you get to talking about the various astronomical timekeeping standards, then throw that into calculations of the various positions of objects as seen in various coordinate systems, I'll get a blank, deer-in-the-headlights look on my face.

However, I did have to look up dynamical time. I got that look, but I did notice something that caught my GR interest: Geocentric Coordinate Time and Barycentric Coordinate Time.

The former (always referenced to the clock rate of an observer "stationary at infinity", and assuming asymptotic Schwarzschild-like flatness) is the proper time of a clock following the motion of the center of mass of the earth, but without the earth's gravity well.

IOW, this is the proper time of a clock following the earth's world line through space and in all the other gravitational fields the earth is immersed in.

Barycentric coordinate time is that of a clock following the solar barycenter's world line through space, but absent the surrounding solar system field.

Doing that allows you to separate all the different effects on clock rates in a structured sort of way.

-Richard

I'm reminded of the proverb: a man with one watch knows what time it is, a man with two is never sure!

Yeah, at any given instant there's a little cluster of Dynamic Times, including the two you mention; and about a minute away there's a little cluster of Universal Times, including UTC.
I just remember that the solar system runs on Dynamic Time (some sort of DT is the independent variable in the equations of motion for the planets), whereas the Earth runs on Universal Time (which is tweaked to keep pace with the rotation of the Earth). The two gradually diverge because of the irregular slowing in the Earth's rotation, which is where all those leap-seconds come in.

Grant Hutchison

I was off-planet that day and missed it

__________________
This is not an idea to be tossed aside lightly - it should be thrown with great force

I just noticed that my computer clock reads 11:40 PM, and you know what that means.....

I should have gone to bed an hour and a half ago.

__________________
At night the stars put on a show for free (Carole King)

One Earth, One Sky - IYA 2009
All moderation in purple

Or, it means your clock is 29 minutes fast!

Well, George Noory had a big proponent of this Galactic Alignment/whatever on last night. He's got a web site,

http://www.thehorizonproject.com/

but it is mostly about selling dvds about his doomsday theories. Which is typical.

Anyway, as the Mayan's foretold, some time around H hour, 11:11AM, D day, Dec. 21st, 2012, the solar system "crosses the galactic *plain*" (that's how he spells it) into something he calls the "dark rift", which is a big gravitational "thing" which is "an extension of the central black hole".

The dark rift causes Mr. Sun and all his planets to shake, wobble, and roll a bit. And we're all gonna die. The earth's crust will shift over the mantle, and we'll have a "pole shift" at least relative to the crust. And this happens over and over again with the precessional cycle. Civillization rises, only to be destroyed by the "dark rift" and start over again.

-Richard

And what makes him think we'll make it that long? Any of us could get hit by a bus, or the whole planet could wipe itself out, within the next five years. Why do people think doomsday models are apocalyptic, and not optimistic?
Interesting how we got ours going so late in the cycle-- kind of waited until the eleventh hour to get TV, didn't we? Such a shame.

I listened to the program. Early in the show, I sent a "fast blast" to point out that if you "stopped the Earth's rotation 'dead in its tracks'" (one of the claims), you would wind up with a ball of impure molten iron. In terms of mis-applied or just flat out wrong science, this was one of the densest shows I've heard in a long time! One of the most blatant was that the bigger the black hole, the faster it spins and the BH at the center of the MW is so big that it is no longer a sphere, but a disk with a hole in the middle like a CD! I could go on and on ...

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

stupidity lurks everywhere

So what would happen to all the energy present in the Earth's rotation? I read Isaac Asimov saying the Earth's rotation stopped suddenly would cause the surface to liquify, in regards to bible literalists saying god stopped the Earth spinning.

__________________
I make my living selling beans which repel ogres, goblins, and sand worms. I eat a bowl a day and have never been attacked!

Not just the surface, but the mantle as well. As I said, "a ball of impure molten iron"!

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

That sounds like an exaggeration. I get a .5 km/s speed corresponds to a temperature increase of less than 50 C, and most of the Earth isn't rotating even close to that speed. I don't see anything melting but the ice, and probably the worst problem would be increased vulcanism.

Would stopping the Earth's rotation be significantly different from
doubling the current rate of rotation? Obviously things like day/night
cycles and a tinsy-weensie change in weight from the loss or gain
of centrifugal effect, but whether you are speeding up or slowing
down, the same amount of energy would be required, wouldn't it?

What I'm really getting at with the above question is I'm not sure
whether stopping the spinning Earth means putting energy in or
taking energy out, or if it is possible to look at it either way.

If stopping the Earth's rotation means taking energy out, I would
think that most or nearly all of the energy could go into whatever
was stopping the Earth, rather than into the Earth.

Alternatively, if stopping or doubling the Earth's rotation means
putting energy in, it seems to me that virtually all of it would be
kinetic energy, with heat only resulting from inefficiency in the
mechanism.

And the part of the Earth that would be heated would be whatever
part of the Earth the mechanism grabs onto. If it grabs the iron core,
then the core would be the part that heats up. But if the mechanism
is efficient, it shouldn't be too bad. Of course, if it grabs hydrogen,
we are in for one big tsunami!

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

There's an efficiency issue, generally you get some heat whenever you do work. But I agree, it's a not really the key point about what science says about stopping the Earth and restarting it-- science has found no evidence that this is possible. That's all you can really say, it's pointless to argue about "whether or not it happened". Nobody knows.

I'm not the least bit interested in whether or not it happened.
I wanna know what would happen if Earth's rotation were
somehow stopped. I had a big argument about this several
years ago, when people were telling Nancy Lieder that Earth's
surface would melt if things went the way she predicted, and I
knew that wasn't right. The energy to change the speed of
Earth's rotation would have to go into kinetic energy, not heat.
Otherwise the speed wouldn't change.

I think.

Do you put energy in, or take energy out? Or is either way of
describing the process equally valid?

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

I'm not sure what you mean here, heat is a form of kinetic energy transfer, it's just disordered (if you shoot a bullet into a hill of dirt, you may be assured that the kinetic energy of the bullet will go into heat). Still, I agree with your basic point that just where the energy will go will depend on just how it is removed from the Earth's rotation.

That some of it will end up as heat is a natural assumption though, because as I said, any process that transfers kinetic energy from one large system to another will generally result in a fraction of the energy showing up as heat, that is essentially the second law of thermodynamics. Then one must assume an efficiency, and then calculate the heat generated. Then there's the issue of where the heat goes (as well as any remaining organized bulk kinetic energy, as you pointed out). So all in all, even if you are obeying the laws of physics, you still have more questions than answers, and cannot say unequivocally that anything in particular will melt. I'm rather surprised a scientist would even choose that approach, when the more natural approach is, "anything's possible in principle, but if we restrict to the realm of what is plausible in terms of reproducible phenomena, there's no way the Earth can be stopped like that, period, regardless of the repercussions. If we go outside plausible reproducible phenomena, then it isn't science, so scientists have little to say on the matter."
There is certainly a difference there, which depends on whether the Earth ends up with more energy or less, but if your point is there's going to be some heating either way, and possibly some melting, I agree.

So lets just put aside the assertion that this stopping of Earths rotation simply could not happen., and I agree, I can not happen. More correctly stated as It will happen that the Earth will become tidally locked to the moon at about the same time as the planet is engulfed by the expanding sun entering its death throws. Even then the Tidal locking will not stop the Earths rotation. Just matching it to the moons orbital period. whatever that might be by then.
So for the sake of the question Its stopped. .
These are not in any order just the random workings of a tired mind.
One hemisphere is going to get very hot as the other will freeze.
Weather patterns will change rather abruptly.
Oceans would freeze and boil and I have little idea what that might do to the weather other than mess it up abruptly
We would all die as would all living things.
The only exception from this dooms day might be if the axis was tilted enough so that an area near the terminator might remain stable although the wind speeds might still get you.
Thats assuming we still have an atmosphere.
Planet Earth would be a very unfriendly place.
Why do you want to be told what seems so clear to me. Use your imagination and think for your self. Being wrong is not yet a crime and caries no punishment other than a little embarrassment that arises from being obviously foolish. Just ask me. I'm good at this.
It could be added that being corrected is furthering my education.
You can not loose

Ken,

My basic point here is that there would not necessarily be nearly as
much heating as people suggested would occur. I agree that such
heating is inevitable if all of the energy of Earth's rotation is put into
the Earth's crust in the form of heat. But since we don't know what
the mechanism is which performs this stopping of Earth's rotation,
we don't know how efficient it is, and therefore have no idea how
much-- if any-- of the energy ends up as heat in the Earth.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Mark,

There has been at least one previous thread here speculating about
what would happen to the Earth if it were not rotating or if it were
rotating at one rotation per year. My interest in this thread is that
I disagree with specific speculations about the amount of heating
that would result from changing Earth's angular velocity.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Hey, the original poster never came back to thank you all for the replies. How rude.

__________________
In your rush to call everyone "entrenched" or closed-minded or "limited" you fail to note that the "limit" here has a very natural boundary: that point at which the evidence stops. - JayUtah

Science fiction was never meant to be an educational tool. - Editor Amazing Tales