Chilean Earthquake Shortened Earth's Day 374
ailnlv writes "Days on Earth just got shorter. The recent earthquake in Chile shifted the planet's axis by about 8 cm and shortened days by 1.26 microseconds 'The changes can be modeled, though they're difficult to detect physically given their small size. ... Some changes may be more obvious, and islands may have shifted. ... Santa Maria Island off the coast near Concepcion, Chile’s second-largest city, may have been raised 2 meters (6 feet) as a result of the latest quake ...'"
Great! (Score:5, Funny)
I can go home a few microseconds early today.
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While at it, also note that Earth rotation period is ~23h56m, not ~24h because the surface of the Earth facing the Sun moves in the opposite direction of the Earth moving around the Sun.
Re:Great! (Score:5, Funny)
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I hear talk on 4chan that he's a witch! Ye best not be speaking with-um again less ye too be dragged before the inquisition!
Re:Great! (Score:4, Funny)
Burn them!!!!
No.
We nuke them from orbit. It is the only way to be sure.
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Einstein said everything was relative and that your perception depends on your point of view.
I just said "the Earth moving around the Sun" to conform to modern standard. I could have said "the Sun moving around the Earth" but then it would have been "in the same direction of the Sun moving around the Earth" but anyway, the principle would still be valid. It always apply for any object shining on another one while one is rotating around the other, or more precisely, when they rotate together around their cen
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What if there were two earths rotating around the sun at the same distance? Wouldn't the sun be stationary then? Hypothetical, but true, no?
Extending this, I guess, then, that there could well be something, somewhere that is actually stationary. In fact, if you take all particles into account, why couldn't it be the sun?
Isn't it true that you can only measure your velocity relative to some other object? However, acceleration is not relative and can always be detected. Since rotation requires acceleration, c
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What if there were two earths rotating around the sun at the same distance? Wouldn't the sun be stationary then? Hypothetical, but true, no?
The question to ask yourself is - stationary in relation to what?
In the solar system frame the sun is mostly stationary (because of its huge mass in relation to the planets), though not completely if you're being pernickety (also rotates and of course it is in orbit around a centre of mass with the planets, but we say they orbit it as shorthand).
In the galactic frame, it's orbiting the centre of the galaxy (along with the rest of the solar system) at something like 568,000 mph, and then the galaxy is moving
Re:Great! (Score:5, Interesting)
Wasn't there a famous quote to the effect that you could say the earth was the center of the universe, but it just makes calculations needlessly difficult?
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Indeed.
Remember calculus 2 and wheel problems? One approach to the equations was to put the center of rotation at the center of the wheel. Another approach is to consider the wheel as rotating around the point of contact with the surface. One seems non-intuitive, but can simplify a bunch of other equations. Or dealing with rotating CoM equations...
Re:Great! (Score:5, Informative)
Einstein said everything was relative and that your perception depends on your point of view.
Velocity is relative, but acceleration isn't relative. Rotation involves acceleration. So it isn't equivalent to say that X rotates around Y is the same as Y rotates around X. (Hypothetical example: consider a universe empty except for a single planet which is rotating. What does it mean to say it's rotating, without reference to background stars? Is it equivalent to a model where we say the planet doesn't rotate? No - we could see the difference in a centrifugal force causing the planet to bulge as it rotates.)
On a funny note Wikipedia says:
"is the astronomical theory that the Earth and planets revolve around the Sun and that the Sun is STATIONARY and at the center of the universe. "
I don't see what's funny? It's perfectly correct that this is what heliocentrism means. And yes, it still wasn't correct - but the point is it was a vast improvement over geocentrism. The Wikipedia article already covers this, at http://en.wikipedia.org/wiki/Heliocentrism#The_view_of_modern_science [wikipedia.org] .
Re:Great! (Score:5, Informative)
Shrinking the sphere and keeping the mass the same will increase the rotation speed. This is why the nutron star left behind after a supernova spins so fast. It's also the reason an ice skater spins faster when they draw in their arms. - Please hand in your geek card on your way out.
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Hu, that's pretty interesting but what's a nutron star again?
Re:Great! (Score:5, Funny)
Irresistible bait for spelling Nazi's.
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Thanks, I didn't think of this obviously ;-))
Here is my geek card, send me your address so I can mail it to you or I can destroy it myself if you wish ;-))
http://www.galacticawatercooler.com/wp-content/uploads/2007/12/geekcard-450.jpg [galacticawatercooler.com]
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It has to do with second moments, rotational inertia, that sort of thing... all very complicated and I don’t remember much of it.
However, what I do remember is this. Basically, for any given mass and assuming that you can’t significantly change its density, it has the least possible rotational inertia if its mass is circularly distributed as close to the axis of rotation as possible*... e.g. a cylinder, sphere, disc, etc. So, a torus (donut) will have more rotational inertia than a disc of the s
Did this affect climate (Score:2, Interesting)
Re:Did this affect climate (Score:5, Funny)
Re:Did this affect climate (Score:5, Funny)
I knew it! I blame the political party I'm not affiliated with.
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I knew it! I blame the political party I'm not affiliated with.
You clueless dolt - it's patently obvious the fault of the political party you ARE affiliated with!
Re:Did this affect climate (Score:5, Funny)
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damn.... that's a bummer.... anyone remember where I parked the H3?
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That lot of bastards? No, it's the People's Judean Front. Next you'll be thinking it was the Judean People's Front or something stupid like that.
Re:Did this affect climate (Score:4, Interesting)
You say this to make fun of the global warming debate, but theoretically it's not completely impossible that underground nuclear testing has something to do with the specifics of any earthquakes since the 1950s or so. Earthquakes are undoubtedly chaotic, and a series of megaton explosions underground might have shaken things a little and helped them get where they're going faster (temporarily).
Mind you, I'm not claiming that's necessarily the case either (or even probably the case). Just that, much like a decent conspiracy theory, it's not entirely nonsense or outside the realm of possibility. (I'd guess that overall seismicity remains the same overall but chaotic effects will change the locations of, say, half the aftershocks next century.)
USGS FAQ here [usgs.gov].
Re:Did this affect climate (Score:5, Insightful)
theoretically it's not completely impossible that underground nuclear testing has something to do with the specifics of any earthquakes since the 1950s or so.
No doubt. Theoretically, it is an absolute certainty that the migration of swallows to Capistrano has something to do with the specifics of every earthquake for centuries now.
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Right, but it only takes a single pebble to start an avalanche.
Now, mind you, if a nuclear weapon ever did trigger an earthquake it would probably just be the trigger event, and the pressure would still have been there from the start. If anything, the nuclear weapon would cause the earthquake to happen sooner, thereby possibly reducing the severity of the eventual quake.
Wow, I just had a brilliant idea. California is worried about the Next Big Quake, and the solution to their problem is so simple - let's
Re:Did this affect climate (Score:5, Informative)
As you probably already know, there are loads of other more mundane ways to instigate an earthquake. This wired article [wired.com] is quite interesting. To summarise:
Re:Did this affect climate (Score:5, Interesting)
In Chaos Theory, a small change to the inputs can cause large changes to the results.
However the changes are just as likelly to go in one direction as they are to go in the opposite direction: the butterfly effect is just as likelly to result in a typhoon instead of clear weather as it is to result in clear weather instead of a typhoon.
Also, small changes to inputs can cause small changes to the outputs or even no changes at all (that's why it's called Chaos Theory) - plenty of butterflies flutter-about with out creating typhoons ;)
If indeed the system that underpins earthquakes is chaotic, underground nuclear tests are just as likelly to have brought forward quakes as they are to have delayed quakes as they are not not have had much effect at all - in fact, they're likelly to have done all of them.
Re:Did this affect climate (Score:5, Funny)
Re:Did this affect climate (Score:4, Interesting)
I actually liked the ACLU until I followed that link. Thanks a lot. Now I'm starting to wonder if they're any less crazy than the Ron Paul fanatics.
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Just because a phenomenon is measurable doesn't mean it's significant.
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The panama canal is almost entirely above sea level...
Re:Did this affect climate (Score:5, Funny)
Q. What do all ice ages have in common?
A. They never happened! That's what they have in common, they have all been concocted by scientists with an agenda to undermine scripture.
And for all those who think that this earthquake wasn't caused by Man ... well it was! Fornication, homosexuality, feminism, democracy, drug-taking, violent video games, on-line porn, science, charity, freedom of speech, blashpemy, etc. etc. all these evils will not go unpunished!
Re:Did this affect climate (Score:5, Funny)
Q. What do all ice ages have in common?
A. They never happened! That's what they have in common, they have all been concocted by scientists with an agenda to undermine scripture.
And for all those who think that this earthquake wasn't caused by Man ... well it was! Fornication, homosexuality, feminism, democracy, drug-taking, violent video games, on-line porn, science, charity, freedom of speech, blashpemy, etc. etc. all these evils will not go unpunished!
Cool ... so how does this work then? Do we just pick our favourite 5 or something? OK ... give me a fornication, drug-taking, on-line porn, with a side of violent video games, and good God why not, throw in some blasphemy!
Now I'm late! (Score:4, Funny)
Awesome! (Score:2)
How often do such quakes occur? (Score:4, Funny)
I mean, don't forget that a day only has 86,400 seconds (give or take...). One such quake doesn't really matter. A hundred won't. A million will start to matter. A billion definitly will.
And of course, they don't happen every day but, well, a billion years ain't that long if you're a planet...
Re:How often do such quakes occur? (Score:5, Informative)
The reason the day length changes is because the quake caused a net motion of mass toward the center of the planet. This reduces the moment of inertia, and because of conservation of momentum, the planet's rotation must speed up.
If this happened repeatedly, it would mean that the density of the planet was increasing. That can't happen to any significant degree, because it would involve compression, which requires a source of energy (note -- I don't mean that the increased rotation is due to an energy input, just that it takes energy to compress a planet). Earthquakes just move energy around, they do not create it. So over long spans of time, earthquakes tend to increase the length of the day by about as much as they decrease it. It all depends on whether the net motion was toward the center of the earth or away from it.
This is based on my knowledge of physics, but I am not a geologist, so there may be complicating factors I don't know about. However, I'm pretty sure that the planet's density cannot increase arbitrarily.
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IANAG, but I would assume earthquakes tend to assist moving matter "downhill"
Re:How often do such quakes occur? (Score:5, Informative)
This is based on my knowledge of physics, but I am not a geologist, so there may be complicating factors I don't know about. However, I'm pretty sure that the planet's density cannot increase arbitrarily.
What goes up must come down...in geology, it's called istosasy. It's sort of like gravitational equilibrium. What sinks in one place is usually offset by a height increase elsewhere. Over years, the small geologic events (and yes, the Chile earthquake is small when measured in geologic units) balance themselves out. I would not worry too much about the lost microsecond. We'll gain it back next year.
Re:How often do such quakes occur? (Score:4, Informative)
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From wikipedia:
>> Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; in terms of energy, each whole number increase corresponds to an increase of about 31.6 times the amount of energy released.<<
This quake was 8.8 ram == 15.8 gigatons of TNT delivered
The one (the comet impact) that owned the dinosaurs was 13.0 ram or 100 teratons of TNT
And we
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a billion years ain't that long if you're a planet...
Yes, it is [ucolick.org]. Our sun's lifespan is about 10 billion years, and it's half-way through. In other word, the solar system should be having its mid-life crisis now.
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Some quakes elevate land which would slow the spin of the earth, but some might lower it, and erosion is constantly lowering the land. After 5 billion years we are probably pretty much in a steady state as far as that goes (earthquakes push it up, and erosion tears it down). Of course other things like tidal forces between the earth and sun are having long term affects which will accumulate overtime (I believe slowing the earth's spin and moving it further from the sun).
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That's assuming every single one shortens the day. Do we know if they'll actually do that, or if there's more likely to be some kind of gaussian spread across positive and negative shifts?
FFS! (Score:5, Funny)
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Seriously! Think of all the things you could do with all that time:
- Make love to your wife
- List all of Pat Robertson's positive traits
- Use WinMo before freaking out and throwing your phone out the window
C'mon people, this is valuable time here!
Re:FFS! (Score:5, Funny)
Oh, for fuck's sake! I've got too much shit to do already! And now, I have 1.26 microseconds less to do it in??!! Scheisse! Of course, maybe I shouldn't post on slashdot. Maybe that would save more than 1.26 microseconds.
You could make love to your girlfriend a couple fewer times per week.
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someone didn't get the joke
GPS affected? (Score:5, Interesting)
Re:GPS affected? (Score:5, Insightful)
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One would hope.
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It's not about the speed of the bomb. It's about the speed of the sattelites which orbit Earth and which the bomb uses to guide itself.
A sattelite travelling in Geostationary orbit clocks 3.8km/s. In 1.26 microseconds it would travel about 5mm. If it, say, takes a month until the government calculates and issues the correcting commands, the offset would accumulate to 15cm.
If a guided missile is launched to fly into a window of an enemy-occupied building, the offset can be enough to make a difference between
Re:GPS affected? (Score:5, Informative)
If a guided missile is launched to fly into a window of an enemy-occupied building, the offset can be enough to make a difference between hitting the window and hitting the wall.
GPS doesn't have the kind of precision to guide a shot like that regardless of whether the time is uncalibrated. If we need to launch a missile into a building and it is imperative that it enter the building through a small window, we would surely use laser or thermal guidance... not GPS.
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The C/A code used by civilian GPS receivers d
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GPS satellites are in low earth orbit, and travel much faster than that, more like 300 km/s. Not that that makes much of a difference here. To first order, each satellite is going to continue on its merry way (i.e. be unaffected by the events on the surface), and the motion of a point on the earth's surface is going to move off of its expected track, in this case sped up by a factor of ~14 parts per trillion.
The inertial velocity of the earth's surface at the equator is ~ 464 meters / second. So a fixed
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Correction: LEO satellites have an orbital velocity of approximately 7800 meters / second, or about 17,500 miles per hour.
Re:GPS affected? (Score:5, Funny)
A James Bond inch? How awesome!
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And then about the non-sarcasm part (Score:5, Insightful)
More people die in car accidents every single day than died in this earthquake.
And that, I think, is actually a real problem---it would be really great if you could somehow get people to drive a bit more safely. It'd save a lot of lives, including the lives of a bunch of productive citizens, i.e. it'd also bring more material wealth for everybody.
Yeah, sure, that shouldn't take the spotlight away from a recent significant event (which also has a lot of wounded and property damage).
But maybe it's something worth pouring resources into?
I know we love sensationalist headlines, but (Score:4, Insightful)
Re:I know we love sensationalist headlines, but (Score:5, Funny)
Remember, this is only what a model predicts, unlike what the headline suggests.
Lemme guess: they used the Quake II engine?
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I'm no Mathematologist (Score:4, Funny)
But according to my calculations, all we have to do is set our calendars back a day... ... in 188,253,750 (ish) years.
I wonder how the PS3 will handle this.
I say everyone (Score:4, Funny)
People of Earth, at 18:00 GMT March 10 we all jump at the same time and regain our microsecond!
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Re:I say everyone (Score:5, Funny)
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If the US jumped a microsecond after China then the US would act as the wall and the earth would bounce into the opposite top corner pocket, haven't you ever played pool before.
Signed
Dave
Re:I say everyone (Score:5, Funny)
If the US jumped a microsecond after China then the US would act as the wall and the earth would bounce into the opposite top corner pocket, haven't you ever played pool before.
Dude, you're doing it all wrong, you want to put ENGLISH on the ball.
global warming (Score:2)
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Not First Post (Score:2)
Missed it by 1.26 microseconds. Damn.
Bad Analogy (Score:2)
“It’s what we call the ice-skater effect,” David Kerridge, head of Earth hazards and systems at the British Geological Survey in Edinburgh, said today in a telephone interview. “As the ice skater puts when she’s going around in a circle, and she pulls her arms in, she gets faster and faster. It’s the same idea with the Earth going around if you change the distribution of mass, the rotation rate changes.”
No, it's not. It's called the "bored to death at the office and nobody's watching" effect. You spin your chair rapidly and lift your legs from the ground. Then put your arms out -- you'll slow down. Pull them back in -- you'll speed up.
Also, "As the ice skater puts when she’s going around in a circle"? Did somebody miss a word there?
Shoddy writing, bad analogies, this is an embarrassment.
ns (Score:2)
Not worth mentioning (Score:2)
The earth is naturally slowing down at a rate that makes this sort of thing hardly worth mentioning. That is why we have leap seconds.
Several milliseconds (per year) total when every year we drift ~500 ms? A few thousand such earthquakes and we might be able to put off a leap second for another year.
Re:Not worth mentioning (Score:4, Interesting)
The earth is naturally slowing down at a rate that makes this sort of thing hardly worth mentioning.
Actually, the slowdown is only about 2ms/century, or about 0.054 microseconds/day. So a 1-microsecond jump in a day should be noticeable. This information is tracked. Here's the raw data from the Earth Rotation Service. [iers.org]
With GPS systems working down to 15cm, changes like this get noticed.
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This 2 ms per century drift in the length of a day is an average. The actual variation [iers.org] is far more erratic - so erratic that this sort of thing seems rather likely to be lost in the noise.
[By the way, clock drift here is the integral of the change in the length of the day per day. Hence the disparity.]
So THAT explains it (Score:2)
I had wondered why the shadow on my balcony tarp, which I use to mark seasonal progress, suddenly took a one-month JUMP shadow-wise. (about three inches)
Holy fuck imagine if we had a 9.9 somewhere.
Ha ha! (Score:2)
So does this mean atomic clocks aren't accurate anymore? Buahah glad I didn't purchase stock!!
Everyone stand up (Score:5, Funny)
I think if everyone in the world stands up and raises their arms for 10 seconds once per year, we can compensate for this.
Its Ok, (Score:5, Insightful)
For us in Chile, the days just got longer (Score:3, Interesting)
For us in the disaster zone (I am in Temuco 100 miles south of the worst hit areas), it feels like 48 hour days. They likly will just get longer as this goes on.
if you want to help, visit http://www.allchile.net/ [allchile.net]
Re:What's with the red headline bar? (Score:5, Funny)
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And spare me the reply saying that "yeah, instead you're the one providing content to the site, which they use to make money off of". There's always someone who says that, and there's always the same answer: If you don't want to be here, don't be here.
Will it affect global climate? (Score:5, Funny)
Yes - the days are shorter, therefore less sunlight per day, ergo - global cooling!
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We must respond to this crisis by enacting more tax cuts for the rich.
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If it affected our tilt (which some of my own simple observations seem to conclude) there might be some changes in our global pattern. Axial tilt IS the reason for the season, after all.
Re:Nit-Picking Science (Score:4, Interesting)
Okay, if this is the case, explain the sudden three inch drop in shadow (I use the shadow on a tarp to determine seasonal change) which usually indicates a full month of time passing, and this happening within two days of the earthquake.
I learned how to read time and the season by the shadows while in prison. Pretty neat when you learn how to do it, but this totally throws the estimation off.
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"Why this tsunami did not ended on Hawaii like the one in 1960?"
This one is easy - the 1960 earthquake was FAR more powerful than 2010. It was out of steam by the time it got close.
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Nearly half a millisecond!
(1.26 * 365.25 / 1000 = 0.460215ms)
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It all depends on who you are. Southwest obviously thinks that Kevin Smith would have a measurable effect.