Ocean Currents Proposed As Cause of Magnetic Field 333
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."
Uh, right. (Score:4, Insightful)
New possibilities in terraforming? (Score:3, Insightful)
Re:Uh, right. (Score:5, Insightful)
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:But this would mean?!?!?!?!? (Score:5, Insightful)
Re:I may be wrong, Im not an astrologer (Score:2, Insightful)
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?
Re:Simply solved (Score:2, Insightful)
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...
Re:Uh, right. (Score:4, Insightful)
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.
Re:Summary wrong: Oceans only small variations (Score:5, Insightful)
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.
Joke or not,,, I was trying to think of other mean (Score:3, Insightful)
the general argument here is that other planets lacking oceans also have magnetic fields-- so that ain't right..
so I'm thinking, what do all solar bodies have in common that could be another means to that end
solar wind? the flow of all the radiation from the sun, wrapping around the planet, and blowing on? happens to all objects in the system??
Because someone has to respond to trolls (Score:5, Insightful)
Funny words from someone who used rather massive ad hominem by trying to label people disagreeing with him as zealots.
Consensus is used as an argument because not all of us can be climate scientists. There is large consensus among them that global warming is happening and caused by men. Not all agree to that. Name any theory and you have people who disagree with it. Hell, there is even a flat earth society. But big majority of the expert who know about the subject and have studied it their whole lives believe so.
Most of the people who argue about it in the internet aren't climate scientists. They've read a few stories which have quoted some climate scientists who disagree with the mainstream and then begin arguing. To them I can always answer "Hey, I am not an expert in the field. And honestly, most likely you aren't either. When your arguments are good enough that they manage to sway opinions of the expert, then you can come back to me. Otherwise I have all the reason to assume that there is some flaw in them."
All of us who aren't experts in every field of science have to do that about some subjects. Trust the scientific method and through that, the experts who employ it.
Re:I may be wrong, Im not an astrologer (Score:3, Insightful)
Just as valid as a hypothesis perhaps, but not as a theory.
A theory requires some evidence and logical reasoning.
While scientists don't "truly know" in that their knowledge is incomplete; they do have a large body of clues, expirmentation and evidence to help them build a more complete knowledge.
You on the other hand simply have given your hypothesis without bothering to look at any clues further than your own skull, or at least you haven't bothered to publish or explain your clues and reasoning to others in any fashion, least of all a repeatable, verifiable fashion that is required for rigorous science.
Thus good scientific theory is indeed more valid than your unsupported hypothesis.
Re:I may be wrong, Im not an astrologer (Score:3, Insightful)
You are certainly right about that. If there is no God then you are no more valuable than a cock roach, because all life climbed out of the primordial ooze. Only a personal God can give personal value.
Bullshit.
Value is given by evaluators. In my case, the evaluators are me, and the people who know me well enough to have a valid opinion of me. I don't need a fancy invisible god to see that human beings are more valuable to human beings than cockroaches.
Re:But this would mean?!?!?!?!? (Score:5, Insightful)
Of course water responds to solar radiation - that's how we get clouds! :-)
Re:I may be wrong, Im not an astrologer (Score:2, Insightful)
I wonder if the idea that Ganyemede has a liquid iron core is based on the assumption that only liquid iron cores cause magnetic fields?
I would wager money that this is true. All our systems of logic are based on assumptions. Our assumptions about other planets are based on earth (because we know it more).
The examples of these moons certainly is insightful to compare with this radical theory of ocean magnetism. However, it is hardly debunked... proof isn't anecdote. Our theories of the moons of Jupiter will change if our theory of the earth changes. Something like this would be a good excuse for NASA to fire off another probe at these moons - this time with extra magnetism, iron core and water measuring sensors.
Comment removed (Score:4, Insightful)
Re:I may be wrong, Im not an astrologer (Score:3, Insightful)
As a physicist you would know that the laws of physics appear to be the same throughout the universe. The binding energies of the carbon atom are just right to make the complex structures necessary for life. There is no other chemistry that we know about that could form any life other than carbon based. Neither scientists nor theologians ever prove anything, but only believe or disbelieve in various facets of their respective discipline.
Of course there's no other chemistry that we know about! Our ability to accurately model complex chemical systems is very limited still, and the vast majority of what we know about chemistry, we know from direct observation of systems in the relatively narrow range of conditions we have here on earth. Maybe in 20 or 30 years we'll have the ability to accurately model the sorts of alternative chemistries that might give rise to different sorts of life, but for the time being, we're limited to what we can see. You're making an argument from lack of imagination [wikipedia.org], which is what the fine tuning argument is in essence.