How can Earth have a mag field if the molten iron nickel is above its curie temp - Page 1
Forum section: electronics / general

author: Beamin
author_rank: Super Contributor
timestamp: October 20, 2018, 04:50:53 pm
content: They never explain this. Is it that its so dense it doesn't come from spin of the atoms or rather the atoms re line up? My understanding is heat takes the spins all out of alignment. Does metallic hydrogen/helium have a currie temp? Also how much can you crush a solid? Normally we think 1-2% like when you cool it. How dense would the core be if you took a CC and brought it up to the surface 2 cc? 1.02 cc?

author: rhb
author_rank: Super Contributor
timestamp: October 20, 2018, 05:48:02 pm
content: 1) This has *nothing* to do with electronics. What is it doing here?2) The origin of the earth's magnetic field is not well understood. The periodic reversals of the field were only discovered in the 1940s. The actual mechanism for its creation and the reversals is purely educated conjecture. As actually collecting data is not possible, it will likely always be a subject of some contention as to what creates the field. But the general view is that it is the result of an electric current, but how that current is generated is a subject of much speculation.3) If you want to discuss such topics, take a course in whole earth geophysics or visit the library and at least learn enough to pose intelligent questions.Your constant attention seeking with your "profound" topics is getting tiresome.

author: raptor1956
author_rank: Frequent Contributor
timestamp: October 20, 2018, 07:59:02 pm
content: You don't need a magnet to make a magnetic field -- all you need is for charged particles to move!Brian

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2018, 09:35:33 pm
content: the molten core of the earth is pretty chaotic from a turbulance prospective right?Do they know if its well mixed? I would assume over 4 billion years the metals are pretty well diffused, but I can imagine a kind of 'composition gradient' forming if there is turbulance in the core, causing heating in some areas and cooling in the other areas, the cooler areas might be precipitating/freezing and the hot areas might be melting a solid shell. I wonder if you can imagine it as a salient forming into an area with different composition causing it to dissolve and introduce different metals into the mix which diffuse throughout the molten core.how well uniform in composition is the solid shell around the molten core?@rhb how does a question about magnetic materials not have to do with electronics? what are we banning discussion on magnetostatic fields now?I find it refreshing compared to the politics and corporate BS

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 20, 2018, 09:42:39 pm
content: I guess the extreme pressure must be taken into account. Most metals, including iron, become superconductors under high pressure.The pressure in earth's core creates some pretty exotic physical conditions,

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2018, 09:46:57 pm
content: the idea of material diffusing into a super conductor to change its size is interesting if it carries a current, similar idea to a flux compression generator kinda. It's kind of like poisoning a catalyst.

author: IanB
author_rank: Super Contributor
timestamp: October 20, 2018, 09:48:38 pm
content: Quote from: coppercone2 on October 20, 2018, 09:35:33 pmIt's not about the subject of the question, it is more about the unintelligent and tiresome nature of this post and so many like it.Quote from: Beamin on October 20, 2018, 04:50:53 pmWhat kind of crazy assertion is this? Who are "they" anyway?I am certain that if I did a bit of research I would find lots of information about the Earth's magnetic field. What I can research, Beamin can research.Questions about geophysics don't really have much to do with electronics. This forum is not where geophysicists hang out.

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2018, 10:13:41 pm
content: I am pretty sure we have a few geophysicists (pretty sure GK is) here that specialize in the oil field but none the less..... i am pretty sure Dave Jones did alot of geophysics research (did you even watch the old videos)? There are also a few experts in DSP from the geophysics area on this forum that I have read the posts of.seriously?i actually bought a magnetic compass last week and I am having alot of fun navigating with it and the whole thing is very interesting.actually, RHB is a geophysicist lol

author: rfeecs
author_rank: Frequent Contributor
timestamp: October 20, 2018, 10:25:30 pm
content: Someone that actually studies this answers the question:

author: chris_leyson
author_rank: Super Contributor
timestamp: October 20, 2018, 11:40:42 pm
content: BepiColombo is on it's long seven year journey to Merury, it's got to do 1 earth 2 venus and 6 mercury flybys to get into a mercury orbit, that's really cool celestial mechanics. You have to deal with the high temperature challenge -180C to +450C on the dark and sun side of Mercury. Then you have to consider the X and Ka band link budgets and Solar flares. That's electronics and that is what this forum is all about.I don't know where your head is at woman ? I don't think you going to find any answers here but try to make an effort to stick to electronics.

author: coppercone2
author_rank: Super Contributor
timestamp: October 21, 2018, 12:12:35 am
content: how is the core not a thermomagnetic electrical circuit according to the video???

author: rhb
author_rank: Super Contributor
timestamp: October 21, 2018, 12:18:39 am
content: Before I strayed from the strait and narrow I was an igneous petrologist. Except for things that can be inferred from seismology, we know NOTHING about the earth's core.And we will NEVER know. Acquiring adequate data is not physically possible.

author: coppercone2
author_rank: Super Contributor
timestamp: October 21, 2018, 12:22:03 am
content: but seriously I don't see this different then asking about magnastars, the ionosphere, hydroacoustic phenomena or even peltier devices working as generatorsif this went into renewable energy (it works like a generator) no one would look because that forum has tons of corporate/financial influence because people wanna save a buck or argue about politicians and solar road waysthreads about insulation or thermal focusing/reflection are common but no one complains even if their only tangentially related to electron flow (and usually people complain the least when they think it might lead to savings on their energy bill).and either someone deleted my video or it failed to post, but there is a experiment going on right now involving a giant ball of molten sodium to work as a dynamo (and it works as a magnetic amplifier but I don't know if he means as a power amplifier that uses heat or just a focusing mechanism/lossy transformer).Also getting this thing to work would be useful if you wanna setup a power generator on mercury or something, since it does not really have any real moving parts other then body corrosion, and you can melt the metal with solar heat and a big heat exchanger. I think it could be made more reliable then peltiers if you spin it around in a pool or something. It's far out but interesting and possible to study clearly. Or maybe spin it in space with some kinda wind force etc.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 21, 2018, 12:38:01 am
content: Some recent studies are saying the core is solid.https://phys.org/news/2018-10-earth-core-solid.html

author: IanB
author_rank: Super Contributor
timestamp: October 21, 2018, 01:14:13 am
content: Quote from: rhb on October 21, 2018, 12:18:39 amI dare say this is a bit pessimistic. We know a huge amount about what happens inside the sun and stars, and they are far less accessible to us.I think we will find the tools to figure out what is going on inside our planet.

author: rhb
author_rank: Super Contributor
timestamp: October 21, 2018, 03:27:05 am
content: Quote from: IanB on October 21, 2018, 01:14:13 amErr...I'm a PhD level geoscientist. It's a major struggle to reach the equivalent of 125 km depth in a laboratory. And that's just to see what happens. You can't actually measure physical properties at those conditions.We have no idea what form and properties iron and nickel take on at core temperatures and pressures. The only data we have is seismic velocity of something for which a sample can never be acquired.Superconductivity is interesting in this context. It is a plausible consequence of extreme temperature and pressure, and the impulse response of a superconducting sphere might explain the field reversals. The superconductivity could be a consequence of some phase transition and confined to a very narrow depth range.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 21, 2018, 03:59:10 am
content: It is a very long step from hard to impossible. While I completely agree that direct observation of the deep earth is extremely unlikely, we are far from exhausting the limits of inference.Someone could have made the same statement you made in 1950. Would you agree that we know nothing more now?

author: Beamin
author_rank: Super Contributor
timestamp: October 21, 2018, 05:53:00 am
content: Quote from: rhb on October 21, 2018, 03:27:05 amYou might know the answer to this:So this is the "they" as in people that explain things I was talking about: "They" say its super dense in the core but how much can you compress a solid? Is it 2% heavier or 100%? How much can you compress a solid with explosive lenses?Does that compression lead to conductivity like how the "ice" in Neptune and Uranus conducts at 1000'C and is hard as iron because it forms a lattice where the oxygen act like nucleuses and the hydrogen float around like electrons?

author: IanB
author_rank: Super Contributor
timestamp: October 21, 2018, 06:28:50 am
content: Quote from: Beamin on October 21, 2018, 05:53:00 am"How much" is the wrong question, because the answer is too easy: you can compress a solid as much as you like. In the center of neutron stars the material is compressed to a tiny fraction of its normal volume, and in black holes it is compressed to what seems like a no volume at all.What you think of as a solid is not really very solid at all. Most of it consists of the empty space between atomic nuclei. It seems solid because the electric field between the atoms holds them rigidly in place, and if you try to compress it the repulsive forces try to push the atoms apart and oppose the outside pressure.However, if you apply unimaginably high pressures you can overcome the repulsive forces between atoms and force the nuclei together.In the normal way, the relationship between pressure, volume and states of matter is called a phase diagram. Solids at earth scale high pressures can have interesting phase diagrams with different arrangements of atoms giving different crystalline forms.

author: Fred27
author_rank: Unknown
timestamp: October 21, 2018, 09:15:49 am
content: Quote from: rhb on October 20, 2018, 05:48:02 pm+1Please give it a rest. It's tedious.

author: coppercone2
author_rank: Super Contributor
timestamp: October 21, 2018, 09:42:47 am
content: I don't think there is a censor on intermediate stages of compressed matter between astrophysical object and ball bearing in a hydraulic pressI think beaming wants to know about a material regime in that region thats not studied well. I have wanted to build a diamond anvil for the last 15 years or so for this reason also.A good diamond anvil will do more pressure then the earths core.

author: EEVblog
author_rank: Unknown
timestamp: October 21, 2018, 10:50:56 am
content: Quote from: coppercone2 on October 20, 2018, 10:13:41 pmOn the electronics and acoustic side, I wasn't involved in the underground reflection and analysis stuff.Even then regular practical geophysics (oil/mineral exporation etc) is all basically surface stuff (for all intents and purposes)

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 21, 2018, 04:37:00 pm
content: Quote from: coppercone2 on October 21, 2018, 09:42:47 amWhile it's true that a pressure 350-390 GPa and more can be achieved with a diamond anvil (letting aside that the pressure at earth's core is just estimated based on several assumptions as nobody can really know), the trick there is to minimize the area to a few micrometers. Plus you need the ~6000K - which seems to be possible with diamond anvils but I would think that investigating the superconductive behavior of NiFe could prove difficult under these conditions (very small area, very hot).

author: IanB
author_rank: Super Contributor
timestamp: October 21, 2018, 04:56:59 pm
content: Quote from: 0xdeadbeef on October 21, 2018, 04:37:00 pmIt can be a very good estimate though. We pretty much know the mass of the earth and its volume, thus its density. We know how to describe the force of gravity. Therefore integrating over the volume of the earth tells what the pressure at the centre would be.

author: rhb
author_rank: Super Contributor
timestamp: October 21, 2018, 05:47:39 pm
content: We cannot and never will be able to study the phase chemistry and physical properties of materials at the sorts of temperatures and pressures at the earth's core.Any statements about the material properties under those conditions are merely speculation based on theoretical calculations.FWIW I know far more about this from getting an MS in igneous petrology than I do from geophysics. Igneous petrologists deal with high pressure and temperature physical chemistry. Almost no one else works in that domain.In any case, the appropriate place for questions like this are a search engine window, *not* the subject line of an EEVblog post. The behavior of an object in a void at the center of a thick walled sphere due to gravity is most appropriately asked in your first semester calculus level physics class.