Magnetic poles

well they are shifting, the shift is speeding up, it affects compasses, but what else?

 

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yeah, I was going to title this pole reversal, but I didn't want to sound like an alarmist nut (I didn't have any articles) thanks for the link then......

 

I don't think we have much to worry about really..given the time it takes to occur.. but

http://www.psc.edu/science/Glatzmaier/glatzmaier.html

'whatever' .. if it does effect the planet.. it already did many times.. if it effects us 'oh well'.

 

I think we can gaurantee it takes longer than individual human longevity.. I appreciate that it could take 300 years or 3000 years.. It certainly takes longer than any human is on the planet, or even within a era of time . I understand it is a gradual occurence, so i think now that we can plot the change; we will calibrate our lives and any systems that will be effeceted..
As we have no control over it and 'what will be will be' thats the reasoning behind me saying 'nothing to worry about'.. I am just certain we will cope..we have in the past under a lot less understanding.

 

Looking at ferrous materials under the atlantic it seems to happen fast, certainly id go for the 300 years if I was given 300 or 3000, though ive heard it could be less but you are quite correct that no one knows.

 

I was talking about magnetic reversal of the poles [nothing else] i have read the last one was 200.000 years and it occurres every 780.000 though other places put it down to 5000 years .. Varying answers from varying studies at varying points over the planet. I don't believe it effects the climate .

This is one of the reasons it does not concern me a great deal..

I don't wish to be sarcastic.. but my posts where not meant to be a thesis on this . I do watch lots of programes on 'science'.. You have to be careful though imho as a speculation can be given merit unduely .. just because it is a 'hot topic' .. I agree that 'science' is ever changing and i do try and keep up as much as i can.. sometimes [a lot of the time i am 'out of touch' though].

What species other that 'us' did this ?.. [me being out of touch].

 

These pole flips are geologically quite common, I cant remember the exact timescale but you can see it in the field driection of ferrite in the Atlantic. It aligned with the Earths M-field when it was a liquid when solidified it froze in that position.

We are in the next flip right now as anyone who regularly does expeditions will have experienced this. In 1978 magnetic North was 7.5 degrees west of grid north and is decreasing by about 0.5 degrees every 3 years (so say the nice people at Ordnance Survey). When this angle becomes large anough teh field will collapse for an unknown period of time and the begin ot reappear with the opposite field direction. All we seem to know about this period is that it is very small by geological standards. As ive said I've even heard decades floated, no one knows exactly but its a stupidly unstable state for the Earth to be in so I cant imagine it lasts very long.

As for the philosophy of science, the more experience I get in the 'biz' the more I realise its just like any other area of life. It goes through its on little fashions with people only reconsidering deeply entrenched positions when the evidence becomes so absurd that it becomes ridiculous. Research proposals are the best, for the last 4 years you'd be amazed how many research projects can be related to national security if you try hard enough.

 

The periods between these flips is known (on the assumption that magma flows from the mid-atlantic ridge at roughly the same rate now as in the past) on average 200'000 years ( I looked this time), the time taken to flip is the unknown quantity. I agree that the variation noted in maps is unlikely to be due to a flip I just put that in to cause some controvosy but I do believe that its been going the same way for quite some time now.

As for the Earth changing its rotation direction thats not going to happen given the Earths angular momentum it would take a fairly colossal force to remove that angular momentum in such a short period of time. Im not sure if your suggesting that the Earths magnetic field reversal goes with a change in spin direction, so ill give you the benefit of the doubt.

And yes I am a physicist and I do have quite an interest in the philosophy of my subject. Science can answer many questions but less be honest thats not usually the spirit its carried out in.

 

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As you have stated tha Earths magnetic field is generated by the movement of highly conductive material in the. As I understand is this movement is some complex result of the Earths rotation, convection within the core and some chemcial processes (I've had a real hard time trying to determine which of these factors is more dominant). However the prevalent Dynamo Model (Parker, 69) which has been used to have a go at explaining these flips (both with the Earth and the Sun) requires no change to the Earths rotation. This theory has been quite successfull for the sun where the periods involved are much shorter.

If the Earths rotation had stopped in the past few thousand years so as to affect drawings on the zodiac I occurs to me that the Earth ceasing to spin may be mentioned somewhere. Given that this would be assoicated with a collapse inthe magnetic field. You would have thought that the resulting mass extinction might pop up in ancient mythology. Even if it did stop it would then need to get going again, and with quite an impressive acceleration. Although I may not know the first thing about physics (infact all ive learnt is how little I know).

 

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Im probably never going to convince you that I know the first thing about physics for a start I never learnt anything about twisting energy. Infact I never learnt about twisting any scalar quantities. When I started university level physics I thought I had a rough idea about how most everyday things work now I KNOW that I cannot explain why hot milk will freeze faster than cooler milk yet its a trick that ice cream makers all over the world do. I thought that given enough computing power I could know everything to aritary accuracy now I know with the exception of a few eigenstates this is not the case, so infact the things we can know become very limited. Infact look at this geodynamo its just a model that we improve on bit by bit its all an approximation to reality not a true simulation of reality.

I know nothing about those legends 3500 years ago so I cant say whether theres anything in them or not. But a collapse in the Earths magnetic field would result in huge irrandiation of the Earths surface from space which is though to be a possible cause of mass extinctions (not big ones like the one that killed the dinosaurs but certainly enough to do some damage).

I have never studied geophysics (apart from doing geography to the end of secondary school) so I know very little about the specifics of the geodynamo theory unsuprisingly basic EM theory such as
Amperes Law and the Biot Savart Law become very complex very quickly when applied to a given situation. But a quick search on google turn up a couple of computer simulations that use current geo dynamo theory and turn up a field reversal in the ic difference that springs into my mind between a normal dynamo and the Earths is that rotating part is liquid. Fluid systems are far more likely to exhibit chaotic properties (stick a drop of water on your hand a guess which way it'll run off) than the rotation of a planet, I would think this a more likely explanatsimulations (using magnetohydrodynamic equations which certainly sound good ). The basic difference that springs into my mind between a normal dynamo and the Earths is that rotating part is liquid. Fluid systems are far more likely to exhibit chaotic properties (stick a drop of water on your hand a guess which way it'll run off) than the rotation of a planet, I would think this a more likely explanation.

Incidentally the slowing of the Earths roation is due to tidal forces transfering mometum to the moon which as a result gets further away each year (about 4cm or so). I guess a primordial Earth would have had a more portly appearance much like Jupiter today. Unless I hallucinated my astronomy lectures along with my 3 (and counting) years of study, sorry im a fairly sarcastic person.

 

The motion of the Earth is coupled to many things though the moon is obviously the main interaction. Also collisions with asteroids and the solar wind will have small effect though this is largely random. But the interaction with the moon is very well known and known to high accuracy (again since atomic clocks provided an accurate time base). At least this is the standard answer and I dont know of any controvasy over this particular area thought id be shocked if I could turn one up if I tried hard enough.

The Earths magnetic field plays an important role in protecting the Earth from radiation. High energy particles usually protons and electrons. Cosmic rays are not only light but also exceptionally high energy particles some quite exotic. These charged particles are defelected by the Earths magnetic field. If they were to pass through the atomsphere and reach the surface they can be as damaging as EM radiation which is absorbed in the radiation.

 

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hot milk freezes faster because the atoms are further apart I think......

at least that's why I always thought so

and I think it also might help make fluffier ice cream, but that might be a placebo affect......

 

well no one has an accepted answer yet so get in their and claim your nobel prize asap before someone beats you to it. Although that maybe one of the theories out there, there are many but none that completely work so far.