Earth's magnetic reversals, and risks..

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chrismb
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Earth's magnetic reversals, and risks..

Post by chrismb »

Excuse me if this has already come up here (I'd be kinda surprised if it hadn't in some form) but one thing that bothers me in the back of my mind is the earth's magnetic reversals, one due soonish, so I understand.

There would presumably be a clear and devastating impact on technology-based mankind that (obviously) previous generations wouldn't have suffered from. I am still inclined to think that we would be severely damaged by the ensuing cosmic radiation - though again historic records do not show extinction events or anything totally catostrophic at reversals.

So what's gonna happen? Are the cosmic rays gonna zap us enough that we can last a few years to breed, but then die early? (This wouldn't show up in geological records.) Will we loose the telly and the internet (worse than a shortened lifespan!?)? And what about all those electric cars we'll have in a few years - and what about all that computerised gubbings for internal combustion engines' control electronics.

The odd thing is, unlike meteor impacts which are probabilistic and therefore *may* never happen so you are at liberty to believe it'll neve happen (if you are so deluded), a magnetic reversal WILL happen, it is unpredictable WHEN it will happen (some signs of it now, a few places dotted around W Africa with reversed fields in - just as the simulations predict) and there seems little doubt that it will fundamentally compromise our electronics and power distrubutions.

Surely there is an immediate need, in global security terms, to get local power generation systems set up, for internet-distrubuted-style robustness (blow GW - this stuff is IMPORTANT!!!) and to figure out how to create buildings that can either protect its occupants from cosmic radiation, or at least so that it can be easily adapted to do so?

Forget GW - shouldn't *this* be at a real panic setting??!!

CaptainBeowulf
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Post by CaptainBeowulf »

My understanding is that the pole switch takes place quickly at geological level, but slowly at a human level. From the last stuff I've read, the weakening of the fields and local reversals seen currently are the beginning of a process that is thought to take a few thousand years. Of course, no one really knows. Some mechanism obviously keeps cosmic rays out, since if the magnetic fields were totally gone for hundreds of years during a slow pole flip you would see regular mass extinctions.

Seems like another candidate for more research to me.

Skipjack
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Post by Skipjack »

I dont think it is going to have much of an effect in regards to the protection against cosmic rays. As had been pointed out, this would have led to mass extinctions before and from what I understand this is rather common event on this planet.
I think that there may be some effect on animals that do use the magnetic field for orientation (some migrating animals). It will be interesting to see how they will be affected by this.

chrismb
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Post by chrismb »

Skipjack wrote:I dont think it is going to have much of an effect in regards to the protection against cosmic rays. As had been pointed out, this would have led to mass extinctions before and from what I understand this is rather common event on this planet.
I aimed to already cover this in my initial discussion - would a big dose of UV and cosmic rays really kill you dead, or just increase your risk of skin cancer and some nasty and early death soon, but not immediately, after? I would have thought the latter, and the latter would also not show up as an extinction event.

I mean - at the last reversal how many bald animals were there that usually spent most of their time indoors and weren't already well-adapted to long times spent outdoors in the Sun? There are typically a small number of people in a normal population who do not have sufficient resistance to the current UV levels that mean they have to spend their lives in doors or they die young with hideous malignancies. They don't die straight away. Nor would we if the radiation levels went up to the point that a significant fraction of people couldn't, similarly, tolerate that increase. Still, there may be plenty of time for them to breed for a replacement generation so no extinction, but a nasty lingering death over a few years of skin malignancies for a large fraction?

Aero
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Post by Aero »

Are we worried about a solar effect or a extra-solar effect. I mean if its solar, then there are day and night cycles. Many living things might learn that if something kills them, they should stay away from it as much as they can. Of course some are to dumb to get out of the rain but then again, rain is not usually fatal. If it is an extra-solar effect then that's bad.
Aero

chrismb
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Post by chrismb »

Aero wrote:Many living things might learn that if something kills them, they should stay away from it as much as they can.
This is exactly my point. A species may develop behaviours or evolve in a way that tends them towards survivial, and I am sure that this will happen -

But how does an individual learn to keep away from things that have killed it?!?! I'm not bloomin' interested in the survival of the species, I have confidence humans will survive*, I'm interested in the particular survival of me and my progeny!!!

*(if there is loss of the electrical and electronic engineering infrastructures, perhaps it will be more medieval bearded types that will be the prime survivors?)

Giorgio
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Post by Giorgio »

The individual who dies will learn from his death but "will not" be able to apply that knowledge a second time.
The others that survive will.

Like it or not, this is the way that species evolve.

chrismb
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Post by chrismb »

Giorgio wrote:The individual who dies will learn from his death but "will not" be able to apply that knowledge a second time.
The others that survive will.
I'm not entirely convinced that it is possible to do this on a short timescale. If it were some thick red gas and you saw people dying in it, then I would agree, people would keep away and the "word" would spread quick-fast. But this would be invisible radiation and people may be scratching their balding and burned heads before many figure out it is radiation. Gee.. many countries of the world still believe in witchcraft and sorcery!....

Giorgio
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Post by Giorgio »

True, the more quick the timescale of the event, the less the survivors will be. If the timescale is quick enough than humanity will simply cease to exist and (if the conditions will permit it) something new will come out from the mud of this planet.
Due to the size of the universe this type of planetarty extinction events are probably at the order of the day, and I think that no one will relly care if humanity ceases to exist from one day to the other (humanity apart that is).
After all, until now, we have not been that succesfull race we belive to be.....

taniwha
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Post by taniwha »

The magnetic field does not protect us from cosmic rays (and certainly not UV rays or microwaves: The Core was absolutely abysmal on that point). The atmosphere does. However, the magnetic fields do, to some extent, protect the atmosphere.

If the flip is gradual (even as fast as a few hours, I think), we have nothing to worry about other than navigation. If it's too fast (probably on the order of minutes to hours), then national grids will be hit hard (much like bad solar storms). If it's really fast, then unprotected electronics will get hit.

Remember: V=Blv*sin(θ) (I don't remember the order for the cross product, and the sign is irrelevant anyway), and it's the voltage that causes problems.

My guess is that at worst, we lose a little atmosphere. Of course, the faster the flip, the less atmosphere, but the more potential for electrical damage.

pfrit
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Post by pfrit »

taniwha wrote:The magnetic field does not protect us from cosmic rays (and certainly not UV rays or microwaves: The Core was absolutely abysmal on that point). The atmosphere does. However, the magnetic fields do, to some extent, protect the atmosphere.

If the flip is gradual (even as fast as a few hours, I think), we have nothing to worry about other than navigation. If it's too fast (probably on the order of minutes to hours), then national grids will be hit hard (much like bad solar storms). If it's really fast, then unprotected electronics will get hit.

Remember: V=Blv*sin(θ) (I don't remember the order for the cross product, and the sign is irrelevant anyway), and it's the voltage that causes problems.

My guess is that at worst, we lose a little atmosphere. Of course, the faster the flip, the less atmosphere, but the more potential for electrical damage.
I believe that the Earth's mag field does protect us from solar cosmic rays. Rather completely, actually. As an aside, i always thought the phrase "solar cosmic rays" was a bit of a misnomer.
What is the difference between ignorance and apathy? I don't know and I don't care.

taniwha
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Post by taniwha »

It's not just a misnomer, they don't exist. Cosmic rays, by definition, come from outside the solar system (thus "cosmic"). In which case, I guess the magnetic field does protect us from solar cosmic rays, along with the hard vacuum of space. However, see below for a more serious treatment.

The magnetic field does protect "us" from the solar wind, though. However, it's not really us that it protects, but rather the atmosphere, as the solar wind would strip it away (or more accurately, the hydrogen in it).

~1kg/cm^2 of atmosphere is pretty effective shielding against charged particles. Compare this to ~0.0075kg/cm^2 (shielding factor of about 4.7e-8: see here * (search for "lithium hydroxide")) for LiOH against neutrons, which are considerably harder to stop. Remember: some cosmic rays do occasionally reach the Earth's surface (mostly in very high places, eg Denver (or so I've read somewhere)).

* Excellent site chock full of information for putting science into "science fiction".

On the other hand, astronauts might have a bad day.

Solar Cosmic Rays
I can think of three things for "the magnetic field protecting us from solar cosmic rays", two of them confusions. The first confusion is a mixup of "cosmic rays" and "solar wind". The other is the sun's magnetic field providing some protection to the solar system from cosmic rays passing through our neighborhood. As for the third idea: "solar cosmic rays" might refer to cosmic rays passing through the solar system, as opposed to "galactic solar rays" passing through the galaxy. I suspect the last might be the case, as I think I may have read "galactic cosmic rays" somewhere.

chrismb
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Post by chrismb »

Giorgio wrote: Due to the size of the universe this type of planetarty extinction events are probably at the order of the day, and I think that no one will relly care if humanity ceases to exist from one day to the other (humanity apart that is).
After all, until now, we have not been that succesfull race we belive to be.....
Really!! I think we have been astoundingly successful!

For reasons beyond that which would fit in a post, I am now convinced that there are almost certainly no other planets with sentient life. Our survival on this planet requires the utmost protection at all costs, until such time as we have moved on to develop other places in the universe.

It is quite true, of course, that no one left would care if all humans died out. kinda the same agument for using up the world's resources at whatever rate we choose - once gone it is not for us to worry about!

Giorgio
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Post by Giorgio »

chrismb wrote:
Giorgio wrote: Due to the size of the universe this type of planetarty extinction events are probably at the order of the day, and I think that no one will relly care if humanity ceases to exist from one day to the other (humanity apart that is).
After all, until now, we have not been that succesfull race we belive to be.....
Really!! I think we have been astoundingly successful!
We have been sucesfull in doing what? Surviving?

Just for the love of making an example, ants and mosquitos have been on this planet from much before than our race, and will be probably on this planet much after our departure.

I like also to believe that sooner or later humanity will start to look outside his home planet, but, at the current technological level, to do so will require the collaboration and the willingness of all the human race. A collaboration that simply does not and cannot exist right now.

I would love to be proven wrong on this, but I think it will not happen.....

Skipjack
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Post by Skipjack »

While I do think that we are successful, I do not think that we are allone.
From a purely statistical POV this seems very unlikely.

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