How Does Magnetism Relate to the Universe and Gravity?

[ThomasFuhlery]

Ok I'm not sure this is in the right forum, and this is a very broad question; I'm just starting to understand magnetism and its relation to the universe. This is basically a bunch of conjecture on my part, could you tell me if I am anywhere near the mark?

The way I imagine it is this: There are a positive and a negative pole on every magnet, and in fact there are positive and negative poles in every substance, only in a magnetic substance the poles are all facing the same direction. A magnetic field describes the magnetic influence of the magnet, and there are so-called “lines of flux” that run in an arc from one end of the magnet around the edge of the field and to the opposite end, representing the attraction that the magnet itself has to its own opposite pole. If it could, a magnet would form an infinite loop around itself...such is the reason why non-solid substances, their poles free to shift in any direction, form spheres. An infinite loop of magnetism; the most natural and stable shape possible in the universe.
Questions: If this is true, How is magnetism related to gravity? Why do things with large amounts of mass still have polar magnetic fields even if they are spherical (planets, stars, etc.)? What is the relationship with metals and actual attraction to one another through magnetism (and does this have something to do with their conduciveness to electricity)?

Thanks

 

[fargoth]

well... the spherical shape of fluids is not an effect of magnetism, the reason for this shape is surface tension.

the magnetic field of stars like the sun is created by their streams of plasma.

A rotating body of conductive gas or liquid develops self amplifying electric currents (thus self generates magnetic field) due to combination of differential rotation (different angular velocity of different parts of body), Coriolis force and induction. Distribution of currents can be quite complicated, with numerous open and closed loops - thus the magnetic field of these currents in their immediate vicinity is also quite multitwisted. At large distance, however, magnetic field of currents flowing in opposite direction cancels out and only a major dipole field survives (diminishes with distance most slow). Because major currents flow in the direction of conductive mass motion (equatorial currents) then the major component of generated magnetic field is the dipole field of equatorial current loop, thus producing magnetic poles near geographic poles of a rotating body.

Magnetic fields of all celestial bodies are more or less aligned with the direction of rotation. Another feature of this dynamo model is that the currents are AC rather than DC - their direction (thus the direction of the magnetic field they generate) periodically (more or less) alternates, changing amplitude and reversing direction (which is still more or less aligned with the axis of rotation).

The sun's major component of magnetic field reverses direction every 11 years (so the period is about 22 years), resulting in diminished magnitude of magnetic field near reversal time. During this dormancy time the sunspots activity is maximized (because of lack of magnetic braking on plasma) and as a result - massive ejection of high energy plasma into solar corona and interplanetary space takes place. Collision of neighboring sunspots with oppositely directed magnetic field results in generation of strong electric field near rapidly disappearing magnetic field regions. This electric field accelerates electrons and protons to high energies (kiloelectron volts) which results in jets of extremely hot plasma leaving Sun's surface and heating coronal plasma to high temperatures (millions K).

Compact and fast rotating astronomical objects (white dwarfs, neutron stars and black holes) have extremely strong magnetic fields. Magnetic field of newrly born fast spinning neutron star is so trong (up to 10^8 Teslas) that it electromagnetically radiates enough energy to quickly (in a matter of few million years) damp down the star rotation 100-1000 times. Matter falling onto neutron star also has to follow magnetic field lines, resulting in two hot spots on the surface where it can reach and impact star's surface. These spots are literally few feet across but tremendousely bright. Their periodic eclipsing during star rotation is believed to be the source of pulsating radiation (see pulsars).

Jets of relativistic plasma are often observed along the direction of magnetic poles of active black holes in centers of young galaxies.

If the gas or liquid is very viscosious (resulting in turbulent differential motion) then the reversal of magnetic field may not be very periodic. This is the case of Earth's magnetic field which is generated by turbulent currents in viscosious outer core.

and Earth's magnetic field is, as far as i know, is creatd by iron in its core...

Magnetic fields are produced by the motion of electrical charges. For example, the magnetic field of a bar magnet results from the motion of negatively charged electrons in the magnet. The origin of the Earth's magnetic field is not completely understood, but is thought to be associated with electrical currents produced by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel. This mechanism is termed the dynamo effect.

Rocks that are formed from the molten state contain indicators of the magnetic field at the time of their solidification. The study of such "magnetic fossils" indicates that the Earth's magnetic field reverses itself every million years or so (the north and south magnetic poles switch). This is but one detail of the magnetic field that is not well understood.

see:
http://en.wikipedia.org/wiki/Magnetic_field#Magnetic_field_of_celestial_bodies
http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html