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NASA Details Earthquake Effects on the Earth
Cuyamaca writes "
NASA
scientists, using data from the Indonesian earthquake
calculated it affected Earth's rotation, decreased the
length of day, slightly changed the planet's shape, and
shifted the North Pole by centimeters. The earthquake that
created the huge tsunami also changed the Earth's rotation." You now have 2.68 fewer microseconds each day to do whatever it is you do.
I don't think we'll have somebody changing the length of days, since that one is defined in the number of seconds (60 * 60 * 24), and a second is pretty well defined by SI:
http://www.metas.ch/en/labors/4/41.html
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If code was hard to write, it should be hard to read
According to this article the moon's orbit is causing our day to lengthen by about 2 milliseconds per century anyway. I, for one, am greatly relieved. ;-)
It is very common. For example, the duration of the day in summer is longer than in winter (no, I'm not speaking of the length of the light period, but of the rotation period of the earth). The reason is that the trees move mass upward in spring (they get leaves) and downwards in autumn (the leaves fall back down), which changes the moment of inertia of the earth. Since trees only grow on land areas, and most land areas are on the Northern hemisphere, this gives a net effect of slower earth rotation in (Northern) summer.
The Tao of math: The numbers you can count are not the real numbers.
While the day may have gotten shorter, the orbital period of the Earth didn't change, so you get the time back over the entire millennium as an extra leap-second.
i heard this two weeks ago...
I think the news here is that they've actually done the calculations. They knew it would change two weeks ago, but not what the final number would be. Slate's "Explainer" had an article on scientists' expectations of this right after the quake.
One man's -1 Flamebait is another man's +5 Funny.
Good question. Right now, the moon is receiving a boost to its orbital velocity every (Earth) day, due to irregularities in the shape of the Earth. This moves the moon farther away and slows down the earth's rotation. Conservation of angular momentum, doncha know? The earth has sped up, in this case. It has gained angular momentum. Since it's rotating more rapidly now, I'd say that the moon receives its boost more often and will move away more quickly. In the (very) long term, and barring further changes, the moon will end up moving farther away, because the earth now has more angular momentum to lose.
Don't blame me, I voted for Durga.
Wow, talk about screwed up thinking.
It's precisely because of conservation of angular momentum that the rotation has increased! Angular momentum must stay constant. The radius of earth has decreased slightly. Thus, in order for the angular momentum to remain the same, the rotation must speed up slightly.
Angular momentum is not the same as rate of rotation. NOT THE SAME!
An SI second is "[t]he interval of time taken to complete 9,192,631,770 oscillations of the cesium 133 atom exposed to a suitable excitation."
Light is used to measure the meter, which is the distance that light in a vacuum travels in 1/299,792,458 of a second. (I seem to recall that a particular wavelength is used for that, but I can't find it now.)
You can never go home again... but I guess you can shop there.
Explain the proverbial ice skater who speeds up her spin as she pulls her arms toward her body. According to you, this can only explained by "adding energy" (what energy?) or "removing stuff" (she lost mass?!)
For some bizarre reasons you seem to think that the r in L=r x p is a constant. It isn't. The earth contracted somewhat after the earthquake, bringing mass closer to the center of rotation and decreasing the moment of inertia.
Your understanding of this stuff is very incomplete.
To determine time dilation, we look at the lorentz transformation, 1/sqrt(1-(v*v)/(c*c)), where v is the velocity and c is the speed of light. The transformation from the perspective of someone that didn't spin with the earth would be going from 1.00000022295876 to 1.00000022295877, a difference of 1 * 10 to the -14th power. So the time difference is 0.00268 seconds per day and the time dilation is 0.000000000864 seconds per day.
The measurement of 2.68 microseconds/day isn't accurate enough to seem to take time dilation into account, but I would bet it was measured from the perspective of someone that is on earth, therefore it would have already been taken into account anyway. Considering that the time dilation factor is slightly smaller than the accuracy maintained by the government's atomic clocks (10 to the -9th seconds / day), I'd consider it negligible.