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Scientists Measure Gravity Change From Earthquake

Posted by ryuzaki0 on from the seismic-remodeling dept.

Science Daily is reporting that scientists were able to use satellite data to watch changes in the Earth's surface caused by a massive earthquake. These changes had two major measurable effects on the region. The massive uplift in the seafloor changed GPS measurements, and the density of the rock beneath the seafloor changed which produced a detectable change in gravity.

99 comments

  1. Feels lighter by mortonda · · Score: 5, Funny

    I thought I felt lighter this morning...

    1. Re:Feels lighter by 0racle · · Score: 1

      What smells like Blue?

      --
      "I use a Mac because I'm just better than you are."
    2. Re:Feels lighter by mortonda · · Score: 1

      the color nine?

    3. Re:Feels lighter by tolan-b · · Score: 1

      no, popcorn and tin in a microwave of course.

    4. Re:Feels lighter by Hoi+Polloi · · Score: 2, Funny

      So I haven't gained 10 lbs? It was just a gravitational shift!? That means I can have another doughnut.

      --
      It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
    5. Re:Feels lighter by mortonda · · Score: 1

      hear hear! :)

  2. "massive earthquake" by Anonymous Coward · · Score: 1, Funny

    How much did it weigh?

    1. Re:"massive earthquake" by Roguey · · Score: 1

      Less than you'd think.

    2. Re:"massive earthquake" by ciroknight · · Score: 1

      Before or after the quake, it changed Gravity, so.. it kind of matters.

      --
      "Victory means exit strategy, and it's important for the President to explain to us what the exit strategy is." G.W.Bush
    3. Re:"massive earthquake" by CarpetShark · · Score: 1

      Quite a lot, if you fell into a fissure that closed on top of you ;)

    4. Re:"massive earthquake" by billdar · · Score: 1
      "Based on this morning's reading, it would be a Twinkie thirty-five feet long, weighing approximately six hundred pounds"

      --
      I am billdar, and I approve this message.
  3. So, how much is it now? by lheal · · Score: 5, Funny

    I have a lot to keep track of, what with my checkbook, blogs, email, vehicle oil changes and tire rotation, bills, and keeping various client networks running.

    So I'd appreciate it if someone could keep track of this whole gravity situation, and just give me a summary. Let me know if we're all about to go floating off into LEO, but otherwise, keep the announcements to a minimum.

    --
    Raise your children as if you were teaching them to raise your grandchildren, because you are.
    1. Re:So, how much is it now? by kfg · · Score: 1

      Let me know if we're all about to go floating off into LEO, but otherwise, keep the announcements to a minimum.

      Because Slashdot needs more Apple rumours and less science reporting.

      KFG

    2. Re:So, how much is it now? by MustardMan · · Score: 1

      I find your ideas interesting and would like to subscribe to your newsletter.

    3. Re:So, how much is it now? by jrockway · · Score: 1

      > Because Slashdot needs more Apple rumours and less science reporting.

      Don't worry, WWDC is next week.

      --
      My other car is first.
  4. Gravity waves discovered? by Harmonious+Botch · · Score: 2, Funny

    Me too. And there was this strange seasick sensation while it happened...must have been gravity waves.

  5. Top-notch editing by MustardMan · · Score: 5, Funny

    Brought to you by the Department of Redundancy Department...

    Detecting "major" quakes - those measuring a magnitude of 7 to 8.9 - which occur frequently is being investigated. NASA's planned extension of the current mission, dubbed GRACE 2, and its enhanced instrumentation should aid in that effort.

    However, Han is hopeful that NASA's planned expansion of the current mission, dubbed GRACE 2, and its enhanced instrumentation, might allow the detection of "major" quakes - those measuring a magnitude 7 to 8.9 - which occur frequently.

    1. Re:Top-notch editing by mailman-zero · · Score: 2, Informative

      Brought to you by the Department of Redundancy Department...

      Detecting "major" quakes - those measuring a magnitude of 7 to 8.9 - which occur frequently is being investigated. NASA's planned extension of the current mission, dubbed GRACE 2, and its enhanced instrumentation should aid in that effort.

      However, Han is hopeful that NASA's planned expansion of the current mission, dubbed GRACE 2, and its enhanced instrumentation, might allow the detection of "major" quakes - those measuring a magnitude 7 to 8.9 - which occur frequently.

      Perhaps it was an intentional use of Chiasmus with the intention of intensifying or bringing greater attention to an important point.

      --
      Let's play video games with mailmanZERO
    2. Re:Top-notch editing by monoqlith · · Score: 2, Funny

      Perhaps, but I think the more likely possibility is that it was an intentional use of mental retardation.

    3. Re:Top-notch editing by foobsr · · Score: 1

      Perhaps, but I think the more likely possibility is that it was an intentional use of mental retardation.

      Or they maybe were anticipating that they were to be "quoted" here (were dupes have kind of a tradition as I was informed), which then would be precognition.

      CC.

      --
      TaijiQuan (Huang, 5 loosenings)
  6. Global Gravity Change is Real by Anonymous Coward · · Score: 2, Funny
    Today, reputable news sources say a catastrophic shift in the Earths Gravity is taking place, "due to massivly overwieght republicans, and their giant SUV's".

    If we don't take this threat seriously, we will all be smashed flat, like pancakes, and grilled by global warming.

    Unconfirmed reports indicate that giant bird-like aliens will arrive shortly, and revel in the pancake carnage, gorging on the waste like so many crows on road kill. The same sources said they do not wish to imply that the aliens are in league with the Bush administration.

  7. magnitude of the change by Vandilizer · · Score: 3, Interesting

    Really bland article I mean I can change the gravitation fields on my desk my moving my glass of water around and I do believe that is measurable. (Maybe not by a satellite.) So anyone out there have an idea of the magnitude of the change. Will athletes gain a boost there by training in a higher gravity environment? What are the effects of the lower gravity environment or is it so insignificant that who cares.

    Or more interesting dose anyone have a map of the earth and differences in gravity in different areas? (I smell a new google map)

    Just my 2 cents

    1. Re:magnitude of the change by Anonymous Coward · · Score: 1, Insightful
      Will athletes gain a boost there by training in a higher gravity environment?

      Of course, sport is more important than science! Why don't you go measure the gravity effects of your glass of water? Oh, that's right, you don't know how to do that. This may not be a groundbreaking development, but it may be a newsworthy accomplishment.
    2. Re:magnitude of the change by Alaria+Phrozen · · Score: 1
      Will athletes gain a boost there by training in a higher gravity environment?
      I've just done extensive research over whether Superman is more powerful than Goku, and I must say very well respected researchers in both fields are at a stalemate. Since a lot of Goku's adult training was in higher gravity levels, I can answer your question emphatically yes.
    3. Re:magnitude of the change by 8ball629 · · Score: 1

      It's very obvious that the Superman from the movies would most definitely dominate Goku. Simply because Goku is a cartoon character and destroying a cartoon is very easy ;).

    4. Re:magnitude of the change by Anonymous Coward · · Score: 3, Funny

      |Or more interesting dose anyone have a map of the earth and differences in gravity in different areas? (I smell a new google map)"

      And all the fat people can move to neighborhoods with lower gravity, Voila! Instant weight loss.

    5. Re:magnitude of the change by imsabbel · · Score: 3, Informative

      The effect is well in line with the natural distribution of the local gravity constant.
      Meaning it should be in the 0.01 m/s^2 range.

      For the simple reason that if it were anymore, the earth would deform to counter that imbalance (molten core, you know).
      That, btw, also limits the height of mountains to about 10-12Km on earth (compare to mars, where to lower gravity constant allowed much larger volcanos)

      --
      HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
    6. Re:magnitude of the change by munpfazy · · Score: 4, Informative
      So anyone out there have an idea of the magnitude of the change. Will athletes gain a boost there by training in a higher gravity environment? What are the effects of the lower gravity environment or is it so insignificant that who cares.


      The full paper as well as a very nice layman's introduction in the Perspectives section is in this month's issue of Science. (Sorry - subscription only. But you may be able to find the text on a preprint server. I'm no geologist, but I haven't been able to find it in any of the obvious places.)

      Basically, they map out a change of 15 microgals (1 gal = 1 cm/s^2) or around 1.5e-8 of the average gravitational field on the earth.

      By comparison, the variation in g with latitude (at constant elevation) is around 0.5 percent, or 300'000 times as much. Variation associated with local geology is around 100 times smaller, but still swamps this earthquake signal.

      What's cool about this measurement isn't that they're measuring something big enough to have any effect on humans, but rather that they're able to measure such a tiny effect at all.

      There are all sorts of processes going on in the earth and in the oceans that involve movements of comparable amounts of mass: changes in glacier and polar icecaps, ocean-atmosphere gas exchange, deep sea current and temperature changes, movement and depletion of underground water, fast moving magma associated with volcanos, slow tectonic changes, etc. And now it seems like it's also helpful in trying to construct detailed models of an earthquake.

      Incidentally, if you were an athlete trying to cash in on lower gravity, you'd be better off training in the Chilean highlands and competing in Puerto Rico - but it still wouldn't help you much, especially compared to biological effects and day to day variation in performance. (http://www.csr.utexas.edu/grace/publications/fact _sheet/3.html)

    7. Re:magnitude of the change by munpfazy · · Score: 1

      What's more, the layman's summary is in the Perspectives section, the paper itself is in the body of the issue as usual.

      Cleary I haven't had enough caffine yet today.

    8. Re:magnitude of the change by munpfazy · · Score: 1

      The "what's more" comment was supposed to follow a prior correction mentioning that "this month's issue of Science" ought to be changed to "this WEEK'S issue of science."

      But that comment seems to have vanished. Perhaps I hit the posting time-limit and didn't notice.

      I think I'd better stop posting now before I get myself into *real* trouble.

      Oh well. At least it gave me a chance to notice a a Vernor Vinge fan posting in this threat. Always nice to run across one of those.

    9. Re:magnitude of the change by Anonymous Coward · · Score: 2, Funny

      Yeah, you just air it on Fox.

    10. Re:magnitude of the change by icegreentea · · Score: 1

      you could do the same thing by strapping on weights to yourself, set up so that the weight distrabution is the same as "normal". or alternatively, they could just do normal resistance/weight training with more weights... maybe run with some sandbags strapped to the legs. its really a lot simplier that way.

    11. Re:magnitude of the change by 8ball629 · · Score: 1

      Thats funny because I was thinking the exact same thing =\.

    12. Re:magnitude of the change by AaronHorrocks · · Score: 1, Interesting

      Load of crap!
      The Earth's gravity can only change with added or reduced mass. This article hints that it is the amount of gravity that has changed which isn't possible through this earthquake. What is possible is that the vector of gravity; (typically down twards the center of the earth) has been changed since dense matter has moved drastically.

      On a side note, the earth tends to pick up 200 lbs every year due to meteorites. If there's any change in the ammount of gravity, that is what's doing it!

    13. Re:magnitude of the change by SnprBoB86 · · Score: 1

      Won't work: this will simply create more gravity that will suck in all the skinny people. Fatsville will collapse into dark matter.

      --
      http://brandonbloom.name
    14. Re:magnitude of the change by Detritus · · Score: 1

      The "amount" or magnitude of gravity can change at the point where the measurement is taken. The Earth is not a static sphere of uniform density.

      --
      Mea navis aericumbens anguillis abundat
    15. Re:magnitude of the change by massivefoot · · Score: 1

      You don't need uniform density. Only spherical symmetry.

    16. Re:magnitude of the change by AaronHorrocks · · Score: 1

      You missed my point entirely.

      The same amount of gravity is there, as before the earthquake. That has not and cannot change. What has changed is which direction (or as I called it, "vector") that the gravity is pulling.
      As the vector changes, your one dimentional equipment for measuring gravity is sure to have a change in values. Go back to Highschool Trig.

    17. Re:magnitude of the change by Detritus · · Score: 1

      Let's say that you are on the surface of a planet that is constructed from two hemispheres of equal size. The northern hemisphere is composed of aluminum and the southern hemisphere is composed of iron. You take gravity measurements at the north and south poles. What are your results?

      --
      Mea navis aericumbens anguillis abundat
  8. Death knoll for 'intelligent falling'? by jnana · · Score: 3, Funny

    Let's hope this is the final nail in the coffin for the theory of 'intelligent falling' proposed as an alternative to gravity.

  9. how does this work? by Anonymous Coward · · Score: 0

    Could someone explain how the earthquake changes gravity? The article isn't quite clear about it.

    Is it in one spot, or for the whole earth? I thought since the mass of the earth doesn't change, neither would gravity, but I'm not that good at physics.

    1. Re:how does this work? by kfg · · Score: 3, Interesting

      Is it in one spot . . .

      Yes.

      Put a cement block on the floor in front of you. Now stand on it.

      Ta da! Instant local gravity increase, because there is now more mass underneath you.

      KFG

    2. Re:how does this work? by JelloCube27 · · Score: 1

      But now you're furthur from the earth's core, so it must cancel out :)

    3. Re:how does this work? by kfg · · Score: 1

      But now you're furthur from the earth's core, so it must cancel out :)

      Whether that is true or not is left as an exercise for the student.

      KFG

    4. Re:how does this work? by Anonymous Coward · · Score: 2, Informative

      Sorry to burst your bubble, but I think you mean a local gravity decrease. Why use one cement block when you could use a million? Take it to the limit! When you step on the cement block(s), you're moved farther away from the center of the earth. The effects of gravity decrease with the square of the distances involved. And I think you can agree that the mass of a million cement blocks will not change the center of mass of the Earth enough to compensate.

    5. Re:how does this work? by kfg · · Score: 2, Funny

      Sorry to burst your bubble, but I think you mean a local gravity decrease.

      I can't help it if you didn't notice the cement block shaped hole in the floor into which the cement block was supposed to be inserted.

      I think you can agree . . .

      Not until you show your work, no, I cannot.

      KFG

    6. Re:how does this work? by Alaria+Phrozen · · Score: 1

      So what happens when I fart? I personally have significantly less mess, but there's also significantly more mass around me (think of the change in size of a blowfish).

      I've stood on a bathroom scale trying to measure this but my instruments are either too insensitive or are too greatly affected by the tremendous resultant atmospheric change. Any ideas?

    7. Re:how does this work? by kfg · · Score: 1

      So what happens when I fart? . . .I've stood on a bathroom scale trying to measure this but my instruments are either too insensitive or are too greatly affected by the tremendous resultant atmospheric change. Any ideas?

      Use a satellite.

      Contemplate other phenomenon that might affect the outcome of the experiment (hint: think of a balloon) and propose a means of compensating for their effect.

      If the satellite turns out to be insufficiently precise ponder the limits of measurment and the concept of significance.

      For extra credit ponder the relevence of your conlusions to measurements of, ummmmm, "gross" atmospheric changes and relate this to public policy.

      This will account for 50% of your final grade.

      KFG

    8. Re:how does this work? by edflyerssn007 · · Score: 1

      He weighs more because all mass underneath him to the surface of the earth on the opposite side is pulling him down.

      -Ed

      --
      So you see what had happened was....
    9. Re:how does this work? by rossdee · · Score: 1

      Depends what the floor is made of - most basements have a concrete floor anyway so there would be no change.

    10. Re:how does this work? by kfg · · Score: 1

      So let's refine the experiment a bit.

      How about we put our g meter on top of a stool, take a reading, and then shove a concrete block under the stool?

      KFG

    11. Re:how does this work? by gameforge · · Score: 1

      When you step on the cement block(s), you're moved farther away from the center of the earth. ...and closer to the center of the cement block. Distance is going to be a bigger factor in terms of the cement block's gravity vs. the Earth's; realtive to your mass & size, Earth is so many billions of orders of magnitude bigger than you; whereas ten or fifteen cement blocks might equal your mass and exceed your density (and Earth's, at the surface anyway).

      A terrestrial mass only a couple of kilometers in diameter owns enough gravity to hold itself together, IIRC from astronomy. If you were to climb a 5km mountain in Colorado, you'd be in a bigger gravity field than if you were below sea level in Holland or something.

      Really, standing on a cement block probably wouldn't produce a measureable increase in gravity for decades to come (until we have the ability to measure it that precisely). But I'm certain standing on something that's on top of Earth's surface does increase the gravity you're subject to, if it has a greater density than you and a greater or equal density as Earth.

      The really intersting question to ponder is, how significant is a human's own gravitational field? If you jump up and down, does the earth measurably oscillate accordingly? What if everyone in Japan jumped up and down synchronously? Given how many people per sq. km. there are?

    12. Re:how does this work? by 4of12 · · Score: 1
      Put a cement block on the floor in front of you. Now stand on it.
      Ta da! Instant local gravity increase, because there is now more mass underneath you.

      Really?

      What I mean is this: does the extra attractive force between you and the cement block more than compensate for the extra distance you've put between yourself and the earth's center of mass (which would tend to decrease the gravitational force you feel from earth)?

      --
      "Provided by the management for your protection."
    13. Re:how does this work? by kfg · · Score: 1

      Really?

      Wellllllll, not with a typical cement block, no.

      does the extra attractive force between you and the cement block more than compensate for the extra distance you've put between yourself and the earth's center of mass

      Gravity falls off by the inverse of the square of the distance. If your cement block is equal in mass to the average of the column of Earth underneath you the mass is only going up linearly with distance and the total force will go down. If it's equal to the square of the average mass you'll break even.

      KFG

    14. Re:how does this work? by kfg · · Score: 1

      He weighs more because all mass underneath him to the surface of the earth on the opposite side is pulling him down.

      But you are father away from the mass on the opposite side, reducing its contribution to the total force.

      Turns out that if you average all the forces it works out to the same as if all the mass were concentrated at the Earth's center.

      If you dig a hole and jump in gravity will be decreased, even though you're closer to the center, because the average force exerted on you by the entire shell of the Earth above your own center of mass averages to zero. You can intuit this easier if you imagine yourself at the center of the Earth, where you would be weightless.

      KFG

    15. Re:how does this work? by edflyerssn007 · · Score: 1

      This is true, but there is a slight increase in the downward direction in gravity even though it is very miniscule.

      -Ed

      --
      So you see what had happened was....
    16. Re:how does this work? by kfg · · Score: 1

      Ahhhhh, but the increase in gravity due to mass is linear. Double the mass, double the force.

      But the force of gravity also follows the inverse square law, get twice as far away and you quarter the force of gravity.

      So if your added mass necessarily pushes you farther away from the center the force will fall off due to distance faster than it increases due to mass, lowering the net force, unless your cement block is very massive. Say about 1000 Kg.

      KFG

  10. Signals in context by Anonymous Coward · · Score: 1, Interesting

    What we really want to know is can this data be fitted to measurements immediately before the quake. Since earthquakes are essentially relaxation oscillations in plate movement very careful extrapolation with some fancy signal processing techniques (linear prediction maybe) might be able to spot some features in the gravity field out in space.

    I think there's no magic bullet for quake prediction, but the solution is a very holistic thing by aggregating lots and lots of different measurements. For example the gravometric measurements may say "there's about to be a quake somewhere on Earth, but we can't say where for sure" while more local measurements might help pin down the likely shift location.

  11. GPS is relative to exactly where? by r00t · · Score: 4, Interesting

    With everything moving all over and us trying to define property lines (including international borders) reliably, we sure do have a mess.

    If GPS is tied to some NAVY building in Maryland and the building moves, do we then declare that the building DID NOT MOVE because it is by definition in a particular place? Everybody else moved?

    (I do not in fact know: it could be an Air Force cave in the Rocky Mountains, etc.)

    If half of the Earth moves relative to the other half, which set of property owners has a problem?

    1. Re:GPS is relative to exactly where? by AdmiralSpearmint · · Score: 5, Funny

      If half the earth moves relative to the other half, I'd think we'd have bigger problems.

      --
      God is dead, Nietzsche is dead, and I'm not feeling particularly good myself.
    2. Re:GPS is relative to exactly where? by PCM2 · · Score: 0
      If GPS is tied to some NAVY building in Maryland and the building moves, do we then declare that the building DID NOT MOVE because it is by definition in a particular place? Everybody else moved?

      Uhhhhh... somebody correct me if I'm wrong, but so far as I was aware, the only thing GPS is "tied to" is a ring of satellites in geosynchronous orbit above the Earth, where they are mostly indifferent to earthquakes. Just because this article (rather vaguely) says that "GPS measurements" changed doesn't mean there was any change in the GPS system itself. One's position relative to a few satellites will still remain that -- one's position relative to a few satellites.

      --
      Breakfast served all day!
    3. Re:GPS is relative to exactly where? by mesri · · Score: 5, Informative

      When you get a position fix from the GPS system, you are combining the information from several satellites, each of which is transmitting a signal of the form, "My name is GPS _X_, I sent this message at time _Y_ from the approximate location _Z_" A GPS receiver triangulates a position by calculating the distance to several satellites, using Center-Of-Earth coordinates.

      It's true that your position is calculated relative to the satellites, but in order for the satellite to know where it was when it sent the message, there has to be pretty accurate data about its precise orbit, which depends intimately on the shape and mass distribution of the earth ("Geosynchronous" is only approximate), so that the final location in Latitude.-Longitude.-Altitude can be given relative to the center of the earth. A big quake could certainly shift things around enough to alter the orbit, which is probably what these researchers were talking about.

      On the other hand, for the purposes of surveying on earth, its certainly conceivable that one could define property lines in relation to the locations of particular GPS antennae, fixed into bedrock or something, and that if those moved, things would be all kerflooey. But that's not new to GPS surveying, since its always been done relative to the location of particular fixed monuments. :)

    4. Re:GPS is relative to exactly where? by Anonymous Coward · · Score: 0

      GPS satellites are not geosynchronous.

    5. Re:GPS is relative to exactly where? by jackbird · · Score: 1

      There are already problems like this in places where international borders are defined by the courses of rivers.

    6. Re:GPS is relative to exactly where? by DerekLyons · · Score: 1
      If half of the Earth moves relative to the other half, which set of property owners has a problem?
      Niether - at least in the US, property boundaries are tied into a local reference.
    7. Re:GPS is relative to exactly where? by XNormal · · Score: 1

      GPS coordinates are relative to the center of gravity of the Earth (i.e. average position of all the mass on Earth) and the rotation axis of the Earth. Longitude is tracked by measuring the average rate of rotation from pulsar signals received in several radiotelescopes around the earth.

      It's all based on averages. The motion of the crust in the biggest earthquakes is still insignificant compared to the total mass of the entire volume of the Earth so it doesn't really affect the GPS frame of reference. The effect on the rate of rotation is small but integrated over time it can accumulate to a significant difference. It is cancelled by the tracking of the rate of rotation.

      In the affected area you will notice the difference in the coordinates of landmarks because they really did move relative to the average position of the Earth. If this ever becomes an issue it should be possible to generate a list of polygons and their motion vectors and transmit it as part of the GPS signal. The receiver could then let the user choose between true coordinates and coordinates corrected to some reference point in time before the earthquake.

      --
      Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
    8. Re:GPS is relative to exactly where? by zettabyte · · Score: 1
      "do we then declare that the building DID NOT MOVE because it is by definition in a particular place? Everybody else moved?"

      Yes, because everyone knows the world revolves around the U S and A!

      Joke Disclaimer: If you think this is flamebait, get a grip on yourself and lighten up.

  12. Recalibrating Equipment by Bender0x7D1 · · Score: 1

    Does anyone know if there are scientific instruments that are sensitive enough that they would have to be recalibrated for this change in gravitational field strength?

    --
    Reading code is like reading the dictionary - you have to read half of it before you can go back and understand it.
    1. Re:Recalibrating Equipment by Alaria+Phrozen · · Score: 0, Offtopic

      I've noticed my left testicle has been hanging a little lower than normal lately.

  13. In other news... by nobodynoone · · Score: 2, Funny

    Britain devalues the pound.

  14. I just have to say that... by Manchot · · Score: 1

    This is heavy, and weight has something to do with it.

    1. Re:I just have to say that... by ScrewMaster · · Score: 1

      Heavy? What is this "heavy"? Is there something wrong with the force of gravity in our time?

      --
      The higher the technology, the sharper that two-edged sword.
  15. Moves how much? by NotQuiteReal · · Score: 2, Interesting
    If half of the Earth moves relative to the other half, which set of property owners has a problem?

    If it moves "a little", the people with a problem with be the ones that are poorer - as usual. By definiton the more well-to-do have the means to fix stuff (or higher a better lawyer to get the "new" property lines drawn in their favor :-)

    On the other hand, if it moves "a bit", (like "end of the world as we know it") then maybe you would have been better off as a hunter gatherer, already in tune with the primative conditions that arise.

    Of course, if it is "really a lot" (end of the world.) Then the point is moot.

    --
    This issue is a bit more complicated than you think.
  16. LIGO by Eternauta3k · · Score: 1

    I'm willing to bet the people at LIGO noticed it...

    --
    Yeah. Would you choose a neurosurgeon who pokes around people's brains in his spare time? I wouldn't.
  17. particle accelerators and moon phases by Paolone · · Score: 1

    I don't think so but particle accelerators have to be properly set up after earthquakes, and LEP at CERN was sensible to moon phases (literally, also the earth itself is bent during tides).

  18. Other gravity changes by massivefoot · · Score: 5, Interesting

    This reminds me a little of a physics practical I did this year. It was supposed to be the first practical where we would get a decent accuracy, measuring g using a pendulum to about 6 significant figures.

    We were also told at the end of the practical about far more accuarte ways of measuring g, and that a university in Germany several decades ago had used this regularly as experimental training for graduate students. However, when the experiment was performed at different times of the year, a small but definte increase in g was noticed during the winter. More accurate measurements showed a sudden spike near the start of winter, followed by a slow decrease until the summer.

    Professors were baffled, until someone remembered that the lab in which the experiments were carried out was above a coal cellar used to store a huge quantity of coal for burning during the winter.

    1. Re:Other gravity changes by IceFoot · · Score: 1

      Very interesting. IAAPM (I am a physics major) and wonder how you can get 6 significant figures from a pendulum. Can you describe the experiment? Was it a simple pendulum, a weight at the end of a wire? Or can you point to a web page with some details? Thanks.

    2. Re:Other gravity changes by massivefoot · · Score: 1

      Sorry, my mistake, the experiment was done at the start of this year and I didn't remember the details. I've now got my lab notes in front of me , and it was only really accurate to 4 significant figures, although I think the error was small enough that we recorded 5 figures. The experiment is done in the first year of the natural sciences tripos in Cambridge, I'm not sure if you can find details on line though. No, the pendulum was not simple, its moment of inertia had to be measured using it as a torsion pendulum first. However, I think I have to defer to your superior expertise in this area, I'm no longer doing physics, I'm in the maths tripos now.

  19. Who needs a new geoid? by Murphy+Murph · · Score: 2, Funny

    That's why real men only work in ellipsoidal heights!

    --
    I dub thee... Sir Phobos, Knight of Mars, Beater of Ass.
  20. Ahh... by Istahir · · Score: 1

    Ahh....so finally, there will be a place where people will fall in love harder !

    --
    Primordial Soup
  21. who cares? by Anonymous Coward · · Score: 0

    There is a greater gravitational pull affecting me when I'm closer to the fridge and I doubt that this change in gravity would have any more of an effect on the people who lost their homes. Seriously, what's the big deal here? they could have just said that because of the earthquake that parts of the crust ended up having different densities. It's true that whenever something changes density, its gravitational pull is slightly altered.

    Oh, look! we weigh 0.001 piconewtons less when we get into a car because of the gravitational pull of the roof. Let's submit it to slashdot!

  22. Big Earthquake by bruno.fatia · · Score: 1

    As long as it doesn't take California away so I can keep watching The O.C. it could blow whole north america away.

  23. I'd mod parent funny, but that's just me by NotQuiteReal · · Score: 2, Insightful
    Sorry, I don't have mod points at this moment, AC.

    If I had them, well, I might give that one - it is almost funny, in a Jon Stewart kind of way.

    --
    This issue is a bit more complicated than you think.
  24. Troll? by WilliamSChips · · Score: 1

    I can see the "Intelligent Falling"ists are out in full play today.

    --
    Please, for the good of Humanity, vote Obama.
    1. Re:Troll? by Anonymous Coward · · Score: 0

      Mod up parent. + 5 Funny!

    2. Re:Troll? by Anonymous Coward · · Score: 0

      Yeah, somebody's abusing their moderation privileges. It's obviously an attempt at humor, and not a troll.

  25. Given enough sensitivity in the instruments... by dinther · · Score: 1

    Given enough sensitivity in the instruments you probably could detect gravity changes when I fart.

    1. Re:Given enough sensitivity in the instruments... by bytesex · · Score: 1

      Cue to the yo mama jokes..

      --
      Religion is what happens when nature strikes and groupthink goes wrong.
  26. I think wikipedia may have the answer by r00t · · Score: 1

    Satellite paths are measured at:
    Hawaii, Kwajalein, Ascension Island, Diego Garcia, Colorado Springs

    Perhaps your GPS unit thus gives you a position relative to the average of those sites. That would be two spots in the Pacific Ocean, one in the Indian Ocean, one in the South Atlantic Ocean, and one in the Rocky Mountains. If things disagree, I'll bet Colorodo Springs wins the argument.

    If you're in Asia or Europe and your land moves... oh well!

  27. Nerd Out by Deliveranc3 · · Score: 1

    Gravity + Macroscope + Nuke the Moon = Profit.

  28. Re:Of Course It Feels lighter :) by Anonymous Coward · · Score: 0

    It's never light when one speaks of the sea...

  29. Being redundant can be fun, as long as its differe by Anass · · Score: 1

    nt!

  30. dark matter/energy by stormi · · Score: 0

    just another nail in the coffin of dark matter/energy.

    wait, there's something here we didn't account for! oh yes, planets....dust... some black holes maybe... etc..

    ok so there's something significantly smaller we didn't account for!

    maybe random events like this in our universe could cause more of our figures to be wrong? sounds more plausible than slapping an impressive name on a mystery.

    --
    "if only i had known i would have been a locksmith." -albert einstein
  31. Why should space be different by Anonymous Coward · · Score: 0

    We all have to deal with potholes down here on earth, why should those folks in orbit get a free ride?