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Earth Science

Ocean Currents Proposed As Cause of Magnetic Field 333

Posted by kdawson
from the round-and-round-and-round-in-the-circle-game dept.
pjt33 notes a recently published paper proposing that ocean currents could account for Earth's magnetic field. The wrteup appears on the Institute of Physics site; the IOP is co-owner, with the German Physical Society, of the open-access journal in which the paper appears. This reader adds, "The currently predominant theory is that the cause of Earth's magnetic field is molten iron flowing in the outer core. There is at present no direct evidence for either theory." "Professor Gregory Ryskin from the School of Engineering and Applied Science at Northwestern University in Illinois, US, has defied the long-standing convention by applying equations from magnetohydrodynamics to our oceans' salt water (which conducts electricity) and found that the long-term changes (the secular variation) in the Earth's main magnetic field are possibly induced by our oceans' circulation."
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Ocean Currents Proposed As Cause of Magnetic Field

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  • Could be... (Score:5, Interesting)

    by houstonbofh (602064) on Sunday June 14, 2009 @06:06PM (#28329609)
    There is enough junk floating on the oceans that the currents could be ferrous.
  • by indre1 (1422435) on Sunday June 14, 2009 @06:07PM (#28329621)
    So basically we know that global warming has taken over our ocean's currents when our compasses start pointing to the south...
    • Re:Polarity switch (Score:4, Informative)

      by Killer Orca (1373645) on Sunday June 14, 2009 @07:38PM (#28330129)
      No, the poles already reversed once in theory http://en.wikipedia.org/wiki/Earth's_magnetic_field [wikipedia.org], and are likely to keep reversing, though none of us will be around to find out.
      • by mustafap (452510)

        >and are likely to keep reversing, though none of us will be around to find out.

        And I doubt that the people around at the time will be around to find out either :o)

      • Re:Polarity switch (Score:4, Informative)

        by vulpinemac (570108) on Sunday June 14, 2009 @10:16PM (#28331077)

        No, the poles already reversed once in theory http://en.wikipedia.org/wiki/Earth's_magnetic_field [wikipedia.org], and are likely to keep reversing, though none of us will be around to find out.

        If you do some non-wiki research, you will find out that Earth's magnetic field has reversed many times over the eons. We're overdue now by several thousand years. This Global Warming may be just another indicator that such a change is imminent.

        • Re:Polarity switch (Score:5, Informative)

          by RockDoctor (15477) on Monday June 15, 2009 @05:46AM (#28333203) Journal

          If you do some non-wiki research, you will find out that Earth's magnetic field has reversed many times over the eons.

          Hundreds if not thousands of direction changes are documented, back into the Triassic at least and possibly into the Late Palaeozoic. There are sufficient that, in more recent times (Cretaceous onwards) the reversal record has been used as a tool for correlation. (Such work may go back further into the geological record ; I've certainly seen it used in Cretaceous mudrock sequences as a petrophysical indicator that can be measured faster and with less skilful operators than other techniques like palynology.)

          We're overdue now by several thousand years.

          For certain values of "overdue" ; the distribution of durations between reversal events seems to be essentially random, and since we're over the average duration between reversals, then one could meaningfully "expect" a reversal sooner rather than later. But once you start looking at the statistics, you have to accept that, if the model is accurate, then the probability of a reversal in the next thousand years (say), is the same as the probability of a reversal in the first thousand years after the last reversal. It's the same logic as tossing coins - if you get ten heads in a row, the probability of your next toss being a head is still 1/2, even if the probability of getting 11 heads in a row is 1/2048. Random variables - love 'em or hate 'em, but you can't predict 'em.
          That said, outside the statistical description of the record, the physical models suggest that some events seen at the moment (decreasing field strength ; regional anomalies) may be precursors to a reversal.

          This Global Warming may be just another indicator that such a change is imminent.

          Has someone been claiming global warming to be related to magnetic field strength? Whooo, can I get a smoke of that? Sounds like good gear.

        • We're overdue now by several thousand years.

          Not to sound ignorant, but why is it that we're overdue for:

          • some magnetic reversal
          • some major earthquake
          • some major meteorite impact event
          • some major ice age
          • some major flooding
          • some major solar flare event
          • some major ocean current changes
          • etc...etc...

          We're overdue for everything, such that, I'm overdue for some coffee.

          I know it's Monday morning: don't worry about being late.

      • Re: (Score:2, Funny)

        by dziban303 (540095)

        though none of us will be around to find out.

        Jesus will be.

      • Re:Polarity switch (Score:5, Interesting)

        by pnewhook (788591) on Sunday June 14, 2009 @11:16PM (#28331427)

        Well magnetic north has moved over 1100 kilometers in the past 100 years, and the motion is accelerating. It is currently moving about 40km per year.

      • by Daychilde (744181) <postmaster@daychilde.com> on Sunday June 14, 2009 @11:36PM (#28331563) Homepage

        I"m trying hard to make a joke about writing down when it happened and referring to that as reverse pole-ish notation, but... I think I'll let it go.

        (I should probably post this anonymously, but hey - I stand by my bad puns!)

    • Re: (Score:2, Funny)

      by atheistmonk (1268392)
      What we need to do is reverse the polarity of the neutron flow.
  • by edittard (805475) on Sunday June 14, 2009 @06:14PM (#28329659)
    Aren't there planets that do have magnetic fields, but don't have oceans? And aren't there moons that are the opposite case?
    • by gardyloo (512791) on Sunday June 14, 2009 @06:29PM (#28329757)

      I can pretty much guarantee that astrologers would have no idea what you're talking about :)

    • by Creepy Crawler (680178) on Sunday June 14, 2009 @06:32PM (#28329775)

      That's correct. According to their theory, moons like Europa should have a rather strong magnetosphere.

      Europa is believed to have a warm, salty ocean under the ice crust. And yet, it shows only slight inducted magnetic field from Jupiter. Contrast that with Ganymede, the only moon with its own magnetosphere and a liquid iron core. Satellite photos dont show very much (or any) water on its surface.

      Hmm.

      • Re: (Score:2, Insightful)

        by Gravedigger3 (888675)

        My question is how the hell can they determine all this information about other planets when we can't even figure out exactly what makes our own planet tick?

        • by Creepy Crawler (680178) on Sunday June 14, 2009 @06:47PM (#28329857)

          The idea of the ocean under Europa is that of an educated guess based upon tidal forces between Jupiter, and the fact that surface composition of Europa is frozen water. Flyovers have taken spectral pictures indicating that fact. They also have taken magnetic force readings and determined that any form of magnetosphere was Jupiters creating.

          Ganymede has a liquid iron core, from which I dont understand how they figured that out. However, many sources say so, including NASA. And it's noted by the natural color of 'streaking on the ice' that the moon does have its own magnetosphere. And it was measured by Flyovers. It's strange that it still has a liquid iron core, al most over planets have frozen. The assumption is that Jupiter tidal forces have insulated it.

          We dont need to understand why and how a liquid iron core creates a magnetosphere. We CAN measure more data points to see if our hypothesis matches with known facts. And this water-creates-magnetosphere seems debunked.

        • by Gerzel (240421) *

          It is a lot simpler on other planets as you often don't have quite as many things crawling around on top of them.

          Also they provide other points of reference allowing us to compare our planet with theirs.

      • Europa's ocean may not have strong currents though. Also there could be multiple causes that don't match every planet. Our sample size is pretty small on the subject. Ganymede might have a magnetic field due to its liquid iron core. And we might have a magnetic field due to our oceans. And Planet X might have a magnetic field due to something else all together.

    • by VampireByte (447578) on Sunday June 14, 2009 @06:37PM (#28329799) Homepage

      I may be wrong, Im not an astrologer...

      If you ask an astrologer a question about the ocean, they'll probably want to know if you're a pisces.

      • I may be wrong, Im not an astrologer...

        If you ask an astrologer a question about the ocean, they'll probably want to know if you're a pisces.

        Good jape, got a chuckle out of that.

        But it's another stolen word, isn't it? Astronomy is the naming of the stars, Astrology should rightfully be the logical study of the stars, along the lines of the word "Geology". Or it could have gone the other way, I suppose, and I'd have "Planetary Geonomy" on my bookshelf.

    • Re: (Score:3, Informative)

      by Bungie (192858)

      Aren't there planets that do have magnetic fields, but don't have oceans?

      IIRC Venus has a weak magnetic field and does not have an ocean.

      • by icebike (68054) on Sunday June 14, 2009 @07:39PM (#28330139)

        As does mars. It has a weak field, but it also is suspected of having a much smaller molten core.

        Europa and Ganymede have molten cores due to gravitational churning.

        So far, molten cores correlate well with magnetic field strength. Oceans, when present, tend to be on those bodies having molten cores, but their absense does not entirely preclude a magnetic field.

    • by Iron Sun (227218) on Sunday June 14, 2009 @06:57PM (#28329921)

      Mercury has a magnetic field, which quite surprised planetary scientists when it was first discovered by MAriner 10, as the prevailing theory at the time was that Mercury's small size would have led to its core solidifying by now and stopping the dynamo that generated the field.

      There's obviously a lot we don't know about planetary magentic fields, and I wouldn't want to judge the entire theory just by something I read on Slashdot, but I find it hard to understand how oceanic currents could account for Earth's magnetic field but not for Mercury's.

      • Re: (Score:2, Interesting)

        by vulpinemac (570108)

        Mercury has a magnetic field, which quite surprised planetary scientists when it was first discovered by MAriner 10, as the prevailing theory at the time was that Mercury's small size would have led to its core solidifying by now and stopping the dynamo that generated the field.

        There's obviously a lot we don't know about planetary magentic fields, and I wouldn't want to judge the entire theory just by something I read on Slashdot, but I find it hard to understand how oceanic currents could account for Earth's magnetic field but not for Mercury's.

        One piece of logic disrupts the idea that Mercury would have a solid core... It's proximity to the sun gives it a surface temperature hot enough to melt some metals. Granted, the opposite side of Mercury is also the coldest place in the Solar System (due to the planet's lack of atmosphere and equal lack of rotation.) This could, conceivably imply a solid core. However, just like boiling water, if you heat one side and leave the other side cold, you create a thermodynamic flow which could generate a magnetic

    • by MrMista_B (891430)

      Yes. Fortunately, as usual, the summary has /nothing to do/ with the /actual/ article that it's referencing.

  • Uh, right. (Score:4, Insightful)

    by pclminion (145572) on Sunday June 14, 2009 @06:19PM (#28329691)
    Yeah, that makes a whole hell of a lot of sense. Why not invent some brand new, goofy theory that applies only to the Earth and not to any of the other celestial bodies that we know have magnetic fields which DON'T have oceans? Has somebody never heard of Occam's Razor? Instead of one theory which works to explain all magnetic fields on all celestial bodies why not invent something stupid for no good reason?
    • Re:Uh, right. (Score:5, Insightful)

      by MrMista_B (891430) on Sunday June 14, 2009 @06:24PM (#28329719)

      Because the other theory hasn't been tested, and might be wrong.

      Ignoring possible alternative theories, especially for unknowns, is no different from adhering to dogma on pure faith alone, and damages scientific inquiry.

      • Re:Uh, right. (Score:5, Informative)

        by pclminion (145572) on Sunday June 14, 2009 @06:33PM (#28329787)

        Because the other theory hasn't been tested, and might be wrong.

        The point is that the chances that each celestial body's magnetic field is due to a unique generator are... Well, let's say that that is not what we typical see in scientific history. Similar effects are generated by similar causes, especially at planetary scales.

        (I see that I've been misled by the summary, as usual. Yes, I should RTFA. But the editors should fucking WTFS in a manner resembling responsible journalism. Could currents in the oceans modulate the magnetic field? Worth investigation, I think.)

        • by MrMista_B (891430)

          True, true, and I admit I was also misled by the misleading, inflammitory summary. Such is Slashdot these days, I suppose.

    • Why not invent some brand new, goofy theory that applies only to the Earth and not to any of the other celestial bodies that we know have magnetic fields which DON'T have oceans? Has somebody never heard of Occam's Razor?

      Better question: Is somebody misinterpreting Occam's Razor? The answer is "yes: pclminion."

    • by sakdoctor (1087155) on Sunday June 14, 2009 @06:29PM (#28329761) Homepage

      Occam's Razor was the razor to own. Then the other guy came out with a three-blade razor. Were we scared? Hell, no. Because we hit back with a little thing called the Occam's Razor Turbo. That's three blades and an aloe strip. For moisture. But you know what happened next? Shut up, I'm telling you what happenedâ"the bastards went to four blades. Now we're standing around with our cocks in our hands, selling three blades and a strip. Moisture or no, suddenly we're the chumps. Well, fuck it. We're going to five blades.

      • Re: (Score:3, Funny)

        by interkin3tic (1469267)

        I like it, occam's razor turbo:

        "Of several acceptable explanations for a phenomenon, the simplest is preferable even when there's good evidence to suggest a more complex explanation and no evidence to suggest the simplest. Furthermore, that evidence is automatically invalidated by the first guy to yell out 'Occam's razor,' especially when the guy makes no attempt to explain himself."

      • ^_^ That was a good onion article, that one was.
        [theonion.com]http://www.theonion.com/content/node/33930 [theonion.com]

        By the by, when did the onion open up their archives? I recall them shuffling articles out of their free page very quickly.
    • Re:Uh, right. (Score:4, Insightful)

      by physicsphairy (720718) on Sunday June 14, 2009 @06:45PM (#28329837) Homepage

      According to the article, there is no direct evidence for the metal currents which allegedly induce the magnetic field. They are inferred on basis of the existence of the field. Venus doesn't have a magnetic field--so we decide it doesn't have a molten iron core. The only reason the 'present theory' is so simple and explanatory is because we arbitrarily decide on the planets' internals are such that our theory is always guaranteed to fit.

      Your generalization is also a bit off, as plenty (probably most) of the large celestial objects have magnetic fields but lack iron cores. The sun certainly lack an iron core. We assume Jupiter's magnetic field is supplied by metallic hydrogen, but it could just as easily support it by electrical currents.

      The magnetic fields are actually quite complex and Occam's razor doesn't mean assuming everything is a perfect sphere, as the classic joke goes. If the oceanic theory successfully explains secular variation then Occam's razor may be more likely to back the ocean theory than the dynamo theory.

      • We have proven the existence of a molten outer core inside the Earth, and the proof doesn't depend on the magnetic field, but rather, seismology. Sound and vibration can travel in any substance as a pressure wave - material compressing and decompressing (P-waves). In solids, vibration can also be orthogonal to the direction of propagation (S-waves). Think of vibration in a string, or in a tuning fork. It is known empirically that S-waves travel through the Earth only to certain depth. Because they can't pro

    • I am neither a geophysicist nor am I an oceonographer nor am I any sort of natural scientist. BUT there is a place for this sort of theory. You're essentially advocating the watchmaker theory.

      "Since all sophisticated machine whose origins we have observed are by an intelligent creator all sophisticated machines are therefore created through intelligent design."

      The alternate scientific theory is that "While intelligent designers do create things (including potentially life) we think the more likely explan

  • by Kleebner (533168) on Sunday June 14, 2009 @06:19PM (#28329693) Homepage
    Fascinating! If true, I wonder how it could effect theories on terraforming. If we got enough open and moving water on Mars could it then develop the field needed to block solar radiation and trap an atmosphere?
    • by jd (1658)

      If it's true, then think more in terms of terror forming. The Earth's ocean currents are showing some dramatic changes as a result of global warming.

    • Which is an interesting question - because it's currently believed that loss of the magnetic field cause the loss of atmosphere and the subsequent loss of water on Mars.
       
      Failing to explain Mars represents a major hole in this theory.
       
      Failing to explain why the Earth's magnetic fields are more-or-less symmetrical, which the core is and the oceans aren't, is another major problem.

  • by Anonymous Coward on Sunday June 14, 2009 @06:20PM (#28329697)

    The Slashdot summary is totally wrong.

    From the abstract of the paper: "I propose a different mechanism of secular variation: ocean water [...] as it flows through the Earth's main field may [...] manifest itself globally as secular variation."

    Meaning: There is a major magnetic field that comes from the molten core. However, certain variations that are as yet unexplained may not result from core phenomena, but from the ocean currents.

    I find this much more believable than the swill in the slashdot summary.

    • Re: (Score:3, Informative)

      by Gravedigger3 (888675)

      Its not totally wrong.

      FTA: "While Ryskinâ(TM)s research looks only at long-term changes in the Earthâ(TM)s magnetic field, he points out that, âoeIf secular variation is caused by the ocean flow, the entire concept of the dynamo operating in the Earthâ(TM)s core is called into question: there exists no other evidence of hydrodynamic flow in the core.â"

      He does go so far to say that there is no examinable proof of a liquid core and that we could have been wrong all these years.

      It does

      • by CheshireCatCO (185193) on Sunday June 14, 2009 @07:12PM (#28329995) Homepage

        He says,

        If secular variation is caused by the ocean flow, the entire concept of the dynamo operating in the Earthâ(TM)s core is called into question: there exists no other evidence of hydrodynamic flow in the core.

        --From the article

        Er, dude, no. We are pretty certain that the outer core is a liquid from seismic wave data. "So what?" you say, "Couldn't the core not be flowing?" Perhaps, but our understanding of how heat moves in a fluid is pretty good. And we know that at some point, in order to move the heat out, the fluid has to convect (as the dynamo model requires). So while we haven't directly measured the flow of fluid in the core, arguing that it isn't happening requires at least some explanation of the lack of convection we have every reason to expect.

        That said, let's look at the notion that the oceans are responsible. This ought to be measurable if it's worth talking about. We can get close enough to the oceans that we should easily be able to measure variations in the local field due to the oceans. Heck, tides and changes in circulation patterns ought to manifest temporal variations that we could measure. No, I don't know that anyone has done these measurements, I would be a bit surprised if no one had. (In fact, if no one has, I ask: why hasn't the author?)

        Also, I'm skeptical by comparison to Europa. That body is in a changing magnetic field that is much more powerful than Earth's (and which changes much more rapidly, every 11 hrs). The ocean required to produce the induced field has something like 3 times (from memory) the salinity of our ocean and only produces a response of ~100 nT. (Our magnetic field is around 50 mT.) I'm... skeptical.

      • He does go so far to say that there is no examinable proof of a liquid core and that we could have been wrong all these years.

        While there is no proof you can put your finger on - rejecting a hypothesis supported by other evidence without providing a replacement for that hypothesis is pretty dodgy science.

      • by Gerzel (240421) *

        Well we DO know that there is liquid iron and rock in the Earth's interior. Volcanos spew the stuff out all the time.

        Now we also know from evidence that the deeper you go, the hotter it gets, miners have encountered this quite a lot.

        Now we also know that hot things tend to melt and with our other evidence we have presence of molten minerals(with quite a large amount of iron in many cases) coming up from deeper in the earth than we can study, as well as a lot of evidence that the heat is spread over the ent

    • Read above.

      Ocean currents are /NOT/ being proposed as a cause of the magnetic field.

      The headline is a lie.

    • by syousef (465911)

      I find this much more believable than the swill in the slashdot summary.

      Take a look at who submitted it. PEBKAC.

      • by Tokerat (150341)

        I wonder when we'll stop being modded as Troll or Flamebait for pointing this out; this is the 10th or 11th bad summary I've seen submitted by you-know-who in as many days. I've been here for 10 years, and said editor is REALLY pretty bad.

        Notice that the quote from the paper sums things up rather clearly - it's the editorial *addition*.

    • Re: (Score:3, Informative)

      by RobVB (1566105)
      A few interesting links with more info about these subjects:

      http://gsc.nrcan.gc.ca/geomag/field/sec_e.php (about secular variation)

      http://en.wikipedia.org/wiki/Magnetic_declination (about magnetic declination, obviously)

      Long story short, magnetic declination is the difference between the geographical North Pole and the apparent magnetic North Pole at any one place on earth. The secular variation they're talking about is the gradual change in that magnetic declination, or the apparent movement of the Earth's
  • Well, relativity simply solved.

    All we need to do is find an object that has a magnetosphere and no aqueous sea.

    How about the Sun?

    • Re: (Score:2, Insightful)

      by Lupulack (3988)

      The sun doesn't appear to have much in the way of flowing iron at its core either. Does that mean that it can't have a magnetic field?

      Essentially the theory stands at : flows of conductive fluid ( salt water, iron, plasma ) can generate magnetic fields. We have no evidence that there is flowing iron in the earth's core, but we have rather a lot of flowing salt water. Hmmm...

    • Better example: Mercury.

    • by Progman3K (515744)

      The sun has a sort of liquid... Plasma...
      Of course the summary for the article is wrong, so we can just make up stuff if we want to.

  • Just last night... (Score:5, Interesting)

    by Anachragnome (1008495) on Sunday June 14, 2009 @07:00PM (#28329939)

    Just last night there was an interesting show on television that focused on the subject of magnetic fields associated with planets.

    There was an experiment covered in the show that was essentially a large, hollow orb filled with liquid sodium (a substitute for the iron at Earth's outer core. It is impossible to reproduce the pressure and heat of our Earth's guts in such a small scale experiment) which was then spun at a comparatively equal rate to that of Earth. The orb began producing strong magnetic fields.

    I somehow doubt that if the same experiment were to be reproduced solely with a thin layer of salt water on the surface (and no sodium inside) that it would produce such strong magnetic fields. That being said, while the thought of Earth's magnetic field being produced solely by the water on the surface is interesting, personally I think it is more then likely a combination of the two factors rather then one alone that produces our protective magnetic field.

    In addition, I wonder if the flux in ocean water levels, historically speaking, coincides with the strength and direction of past magnetic fields as recorded in ancient lava flows. If so, this would seem to back up the theory proposed in the article.

    • Re: (Score:3, Interesting)

      by db32 (862117)
      [Citation Needed]

      Seriously...please do. I was aware of the whole molten sodium ball thing because I remember that spinning 13 tons of molten sodium could be a REALLY bad idea. However, the last I saw of it they were still preparing and had not actually done anything yet.

      Also...TFA isn't saying the field comes from water, it says variations in the field come from water passing through the main field. In typical /. fashion the summary is nonsensical crap.
      • by dissy (172727)

        I was aware of the whole molten sodium ball thing because I remember that spinning 13 tons of molten sodium could be a REALLY bad idea. However, the last I saw of it they were still preparing and had not actually done anything yet.

        The last I've heard on that very subject was from a NOVA documentary called Magnetic Storm, which aired in November 2003.
        In that documentary, they were just preparing for the experiment with the molten sodium, but did not start.
        Which sounds like about the same state you have last heard about as well.

        I would have hoped in 6 years time they would have been able to start their experiment but I can not find any updates on their work.
        I too would be curious to know what resulted from it.

        In case you are interested

  • by John Hasler (414242) on Sunday June 14, 2009 @07:07PM (#28329967) Homepage
    The paper [iop.org] does not say that ocean currents cause the magnetic field. It hypothesizes that ocean currents cause secular variations in the magnetic field.
  • We might have proof of this in the foreseeable future. If we keep warming up the planet, it's quite possible that one or more major ocean currents will start behaving differently. If that happens and we see a change in the magnetic field, that would provide a strong hint that the two are connected in some way.

    • by Gothmolly (148874)

      Except NASA has just published data which suggest that the Solar cycle strongly influences the Earth's climate, more so than AGW. So go back to being irrelevant, Al Gore.

  • Wow, that's quite the fish story. Pretty interesting hypothesis though it needs solid, er, liquid evidence to back it up... otherwise it's flowing into the dust bin, er, drain of science history as a pretty darn cool and silly theory that didn't make it.

    Well actually he's saying that there is a "main field" and that the ocean currents are a modification or additional field. Cool. Cutting edge science can be fun. It's where cross currents of ideas and beliefs mix until evidence eventually coalesces with a vo

  • by rlseaman (1420667) on Sunday June 14, 2009 @07:09PM (#28329979)
    Note how this dishes the favorite argument of pseudoscientists, who always (always, always) claim that the scientific "establishment" refuses to hear evidence that conflicts with accepted wisdom. Rather - to the extent that such an establishment can be said to actually exist - science will entertain any sort of extreme argument, as long as it is cogently - and entertainingly - presented. To overturn competing theories extreme arguments ultimately demand extreme evidence, however.
    • by osu-neko (2604) on Sunday June 14, 2009 @08:24PM (#28330405)
      Science has always reserved its greatest accolades for those who prove what came before to be wrong, and every scientist in the world knows the best way to become famous is to prove everyone else wrong. Nevertheless, pseudo-scientists always argue that scientists have some vested interest in preserving the current order (and thus dooming their careers into obscurity when they could have become famous Nobel prize winners). This argument has never made any sense, but that doesn't stop them from making it. So, one more example won't make any difference to them -- people who advocate a bad argument that runs counter to evidence are not dissuaded by more evidence.
  • Winds (Score:4, Funny)

    by 4D6963 (933028) on Sunday June 14, 2009 @07:18PM (#28330033)
    Ocean currents? Here's an even better idea : winds! I know it's true because when I throw a fridge magnet in the wind it goes in the same direction. So next time you want to know in what direction the wind is going, just look at a magnetic compass!
  • Language matters (Score:2, Interesting)

    by Mr_Chang (1576589)
    "The currently predominant theory ...of Earth's magnetic field"

    To be certain, there are NO 'theories' for Earth's magnetism, only a variety of HYPOTHESIS'S.

    Once again the term theory is being misused for HYPOTHESIS. It is a great disservice to science and scientists to not understand the definition and implications for both terms.

    A worker whose research achieves the level of Theory is among the 'Nobel class' of scientists. Therefore the term should be used properly and with some reverence.

    So before

  • This link to an article on NPR, http://www.npr.org/templates/story/story.php?storyId=90947943 [npr.org], was also in a short show on the Science Channel about magnetic fields. So, I think that the reader should not state that there is no evidence that the molten inards of the Earth are not the probable cause of our magnetosphere.

  • TFA and the Slashdot summary are both wrong. The paper doesn't allude that the ocean causes the field. It says that the field is affected (modulated) by the oceans. So the earth could be a permanent magnet, with some of the changes in its field explained by the ocean currents.
  • I'm highly skeptical of this idea for one reason. The volume of the oceans is MINISCULE compared to the volume of the outer core. In order for the oceans to generate the kind of magnetic field the Earth has, they would need to be highly magnetic. Steel ships orient themselves to the currents automatically type levels. The Earth we see is a wafer-thin skin on the massive iron/nickel mass that is the Earth

    • I guess the question here, is how much water is in the mantle? It seems like volcanic plumes from pretty deep within the earth's crust and below have -steam- pressure in them. One has to wonder if the earth is rather like a giant sponge...a big chunk of rock, yep, but saturated with water.

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