Mk
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I need to know all the bad things that will happen if and when the Earth's geomagnetic poles will shift. Also, about every 11 years when the sun's poles change what happens to the sun?
What happens when Earth's geomagnetic poles shift?
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Mk
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also, if there was no magnetic field on the earth, how many feet of concrete or lead would you need to sheild electronics, any type you know
Andre
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Well, you have to retune all the TV and computer screens for instance. Or use them upside down. 
Marijn
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If there wouldn't be a magnetic field we'd probably be all dead.
The Earth's magnetic field shields not only electronics from radiation, but also us.
The Earth's magnetic field shields not only electronics from radiation, but also us.
Crumbles
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The Earth's magnetic field shields us mainly from plasma (mainly charged particles) coming from the sun during solar flares by deflecting them. When such particles get through the atmosphere, you get what is commonly known as an aurora. This looks like some curtain of light (http://www.crh.noaa.gov/grb/images/aurora.jpg)
I am not really sure about the other effects that a reversal in the Earth's magnetic field would do but animals that use the Earth's field as a means to navigate would end up in confusion. And hikers, boy-scouts would get lost because their compasses would point the wrong way. But planes and helicopters will not be affected coz I think they use gyroscopes for navigating. (http://science.howstuffworks.com/gyroscope3.htm)
Also, I believe that power grids could be brought down.
A really dramatic version of the loss of the Earth's magnetic field is what the film 'The Core' is about. But the physics in this movie is really bad.
http://www.intuitor.com/moviephysics/core.html
I am not really sure about the other effects that a reversal in the Earth's magnetic field would do but animals that use the Earth's field as a means to navigate would end up in confusion. And hikers, boy-scouts would get lost because their compasses would point the wrong way. But planes and helicopters will not be affected coz I think they use gyroscopes for navigating. (http://science.howstuffworks.com/gyroscope3.htm)
Also, I believe that power grids could be brought down.
A really dramatic version of the loss of the Earth's magnetic field is what the film 'The Core' is about. But the physics in this movie is really bad.
http://www.intuitor.com/moviephysics/core.html
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Mk
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I thought I'd get lots of stuff... well so far what I do know is that it will have affect on animals that use magnetic stuff in their brain to navigate, like birds, they would die off... that'd be bad, because they'd migrate south...
The plasma from the sun yeah... I got all about that except how much lead or concrete you'd need to sheild any type of electronic.
We'd know about the pole flip ahed of time, because the current field would decrease to 20% of what it is now.
The plasma from the sun yeah... I got all about that except how much lead or concrete you'd need to sheild any type of electronic.
We'd know about the pole flip ahed of time, because the current field would decrease to 20% of what it is now.
Andre
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Well, the Earth magnetic field collapses globally about every 50,000 to 100,000 years for a few thousand years. Then it recovers again. This is called an Paleo Magnetic Excursion. Sometimes it appears that the magnetic field collapses locally. The last local event was possibly the Mono Lake excursion, 26,000 years ago, the last global event was the Lachamps excursion of 40,000 years ago. Before that we had the Blake excursion, 100,000 years ago. So we are not due yet, if any predictions can be made at all.
The last magnetic pole reversal was the flip from the Matuyama chron the present Brunhes chron 780,000 years ago. (obviously a chron is the era between pole reversals). The last 50 million years ago the chrons average about half a million years, so if one can say anything the next pole flip appears to be late.
There is no evidence for extinction upheaval related to paleo magnetic behavior whatsoever. So changes are that the environment won't notice a lot. One could image that a magnetic flip is slow enough for indiviuals to reprogram their magnetic registration devises if they exist at all.
The last magnetic pole reversal was the flip from the Matuyama chron the present Brunhes chron 780,000 years ago. (obviously a chron is the era between pole reversals). The last 50 million years ago the chrons average about half a million years, so if one can say anything the next pole flip appears to be late.
There is no evidence for extinction upheaval related to paleo magnetic behavior whatsoever. So changes are that the environment won't notice a lot. One could image that a magnetic flip is slow enough for indiviuals to reprogram their magnetic registration devises if they exist at all.
Crumbles
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Mk said:
I am not completely sure about this but assuming that the effects of a pole flip leads to only plasma radiation and change in the magnetic field direction, I very much doubt that electronics would need some form of shielding.
I would think that the plasma radiation would be absorbed by the atmosphere before it reaches ground level. And in case it doesn't, since the radiation is made up of charged particles, you could for starters have your electronics enclosed in a metal case that is grounded to earth. Now, I don't now about how deep plasma ions penetrate, but depending on their penetration depth, you might need a denser material to stop it.
As for the magnetic field flip itself, I don't see why it should affect electronic devices. If it was to affect electronics, then rotating any electronic device we currently use about the vertical axis by 180° would lead to a malfunction! This would mean that if I face the window instead of facing the wall when using my computer, it would not work anymore, :surprise: which is totally untrue. So, I would say that the change in direction of the field will not have a direct impact on electronics.
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Marijn
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Crumbles said:
hmm, i thought the magnetic field actualy shielded us against all sorts of cosmic radiation.
Guess someone gave me some bad info once.
Mentor
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It doesn't. Its nowhere near strong enough.Crumbles said:
When it collapses, it'll allow more solar plasma into the atmosphere, make prettier aurora and maybe allow solar flares to cause more damage to satellites, but that's about it. Its not going to kill anyone.
Andre
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I wasn't kidding. Just turn your TV set upside down. Now the correction for the Earth magnetic field, affecting the electron beam is pointing the wrong way.
Crumbles
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Andre said:
Turning your TV set upside down does not mimic the magnetic pole flip. Turning your TV round 180 degrees does!
Crumbles
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The reason your TV might go funny if you turn it upside down would probably be due to gravity more than the Earth's magnetic field.
Crumbles
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The only place where turning your TV upside down would possibly mimic the magnetic field flip is at the poles. But even that would be assuming that the gravitational effects do not affect your experiment. 
lifeblack
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I read an article recently describing the process of a magnetic field reversal. Summarizing, what happens is that the magnetic field locally collapses in one or more parts of the world, the overall magnetic field then becomes progressively disorganized, multiple magnetic poles appear locally (with a much weaker overall field), and eventually the orientation of one of the local anomalies becomes dominant and the Earth's overall field recovers, pointing in this new (perhaps the same as the old) direction. There was also a decent amount of information about the convection currents in the outer core, but I can't remember the details well enough to post about them.
Now, as for whether the Earth's field is in the beginning stages of a reversal, that's still up in the air. However, a magnetic anomaly in the south atlantic has become much more prominent with time, and is to the point where astronauts in low Earth orbit have to take precautions during active storming periods. The Earth's' overall field has been declining at a fairly steady rate for most of recorded history, though I forget the way the field was measured.
Now, as for whether the Earth's field is in the beginning stages of a reversal, that's still up in the air. However, a magnetic anomaly in the south atlantic has become much more prominent with time, and is to the point where astronauts in low Earth orbit have to take precautions during active storming periods. The Earth's' overall field has been declining at a fairly steady rate for most of recorded history, though I forget the way the field was measured.
Evo
Staff Emeritus
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Here is a great link. Click on the "Program Transcript" on the right under resources for the complete dialogue. I think it will put your mind at ease. It's worth the read.Mk said:
http://www.pbs.org/wgbh/nova/magnetic/
Mk
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Thanks, all.
Staff Emeritus
Science Advisor
Gold Member
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Only one aspect which the Nova program may not have addressed sufficiently - would there be widespread electrical grid failures if the magnetic field reversed? A: if nothing were done to today's grids, yes. However, we now know quite well what you have to do to make a grid robust to geomagnetic storms, so the only reason future grids would fail (when the Earth's magnetic field weakens greatly) would be sheer incompetence (or short-sighted, near-term profit driven stupidity) on the part of the grid owners and national regulators.
Evo
Staff Emeritus
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Nereid, excellent point. I wonder if this is something that is being considered right now. We have enough forewarning to prepare for it.
Andre
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Well, the question of course is if technical solutions can defeat physical laws. It's not the same as the Y2K bug.
But the pole shift don't happen overnight, the last one is pretty well documented.
http://staff.aist.go.jp/hirokuni-oda/Odaetal2000GJI.pdf
http://staff.aist.go.jp/toshi-yamazaki/publication/EPS0406.pdf
The Brunhes Matuyama flip seem to have been redated from 780,000 to 789,000 years ago. It lasted perhaps up to 11,000 years and was characterized by numerous violent pole movements at random over the globe. If your electronical devices are sensitive to the Earth magnetic field, then there may be hundreds of years left to think about countering that flip, if at all.
But the pole shift don't happen overnight, the last one is pretty well documented.
http://staff.aist.go.jp/hirokuni-oda/Odaetal2000GJI.pdf
http://staff.aist.go.jp/toshi-yamazaki/publication/EPS0406.pdf
The Brunhes Matuyama flip seem to have been redated from 780,000 to 789,000 years ago. It lasted perhaps up to 11,000 years and was characterized by numerous violent pole movements at random over the globe. If your electronical devices are sensitive to the Earth magnetic field, then there may be hundreds of years left to think about countering that flip, if at all.
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Locrian
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I don't understand what could cause both a magnetic field, and a magnetic field reversal. For instance, if our planet had a slight electrical charge, then when it spun it would create a very nice magnetic field as observed. This whole pole shift business rather ruins that cute proposition.
Anyone have a second to explain what's going on, or a good link that explains the field and why it changes? I could do a net search, but I've become wary of the information I get from them.
Thanks in advance.
Anyone have a second to explain what's going on, or a good link that explains the field and why it changes? I could do a net search, but I've become wary of the information I get from them.
Thanks in advance.
Andre
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Locrian,
The present scholar view about what is causing all that Earth magnetic activity is called the "geodynamo".
A lot of tech talk so I try to simplify it. Magnetic fields are basically rotating electric fields. When charged partices move around they create an magnetic field. Now, if we look at the internal structure of the Earth, we see deep in the interior, a solid inner core and a fluid outer core under a more or less solid mantle.
Somewhere and somehow in that system, heat is generated. This heat causes expansion of masses and the resulting difference in densities causes movement. Hot light fluid material wants to go up away from the solid inner core, but cools in the process and descends down again. This process is called convection, and the movement is a sort of continious rotation in the fluid outer core. Now, if for some reason the molten iron of the outer core has an electrical charge by exchanging electrons to the mantle perhaps. I don't know. The convection rotation cells cause a magnetic field and, due to their sizes, a gigantic strong magnetic field too.
However imagine that all those convection cells couter rotate, to balance each other, then each magnetic field of those cells is canceled out by the other cells spinning in the other direction, but since this is a chaotic process, the sum is not exactly zero and a slight residual magnetic field is remaining.
Now all those chaotic processes are constantly changing. Some cells get stronger, others weaker, and consequently the Earth magnetic field. Right now the counter clockwise rotating cells seem to be stronger, yielding the magnetic north pole at the north pole.
As the simulations of Glatzmaier show, occasionaly the chaotic processes destroy the common convection structure and an so a called (Paleo) Magnetic Excursion devellops where the magnetic field collapses. There is plenty of evidence for those paleomagnetic excursions in the past. They happen roughly every 100,000 years, the last one either 26,000 (Mono Lake) or 40,000 years ago (Lachamps) depending on definitions. So we are not due yet.
If after such an event the convection cells restore, sometimes the opposite rotating cells may end up stronger, then we have a magnetic flip or a pole shift.
I can see some weaknesses in the hypothesis but it also dove tails nicely with my pet idea about what really happened in the Pleistocene.
The present scholar view about what is causing all that Earth magnetic activity is called the "geodynamo".
A lot of tech talk so I try to simplify it. Magnetic fields are basically rotating electric fields. When charged partices move around they create an magnetic field. Now, if we look at the internal structure of the Earth, we see deep in the interior, a solid inner core and a fluid outer core under a more or less solid mantle.
Somewhere and somehow in that system, heat is generated. This heat causes expansion of masses and the resulting difference in densities causes movement. Hot light fluid material wants to go up away from the solid inner core, but cools in the process and descends down again. This process is called convection, and the movement is a sort of continious rotation in the fluid outer core. Now, if for some reason the molten iron of the outer core has an electrical charge by exchanging electrons to the mantle perhaps. I don't know. The convection rotation cells cause a magnetic field and, due to their sizes, a gigantic strong magnetic field too.
However imagine that all those convection cells couter rotate, to balance each other, then each magnetic field of those cells is canceled out by the other cells spinning in the other direction, but since this is a chaotic process, the sum is not exactly zero and a slight residual magnetic field is remaining.
Now all those chaotic processes are constantly changing. Some cells get stronger, others weaker, and consequently the Earth magnetic field. Right now the counter clockwise rotating cells seem to be stronger, yielding the magnetic north pole at the north pole.
As the simulations of Glatzmaier show, occasionaly the chaotic processes destroy the common convection structure and an so a called (Paleo) Magnetic Excursion devellops where the magnetic field collapses. There is plenty of evidence for those paleomagnetic excursions in the past. They happen roughly every 100,000 years, the last one either 26,000 (Mono Lake) or 40,000 years ago (Lachamps) depending on definitions. So we are not due yet.
If after such an event the convection cells restore, sometimes the opposite rotating cells may end up stronger, then we have a magnetic flip or a pole shift.
I can see some weaknesses in the hypothesis but it also dove tails nicely with my pet idea about what really happened in the Pleistocene.
Locrian
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Thank you Andre, that was a great link. I actually had one important fact wrong; I thought the flips in the magnetic field were evenly spaced and predictable, and that link disposed of that misconception. It's an interesting theory and I'll do some more reading on it when I can.
Mk
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Special thanks to Andre, Crumbles and Tide