PDA

View Full Version : Another question about pole shifts



Jens
2007-Oct-26, 03:44 AM
There is a thread about the 2012 garbage, but it got me to thinking about something. The sun's magnetic poles change (I think regularly) every 11 years, and planets also have changes like that. What I'm wondering is, is this something that only happens to stars and planets? What about galaxies? And what about smaller things, like say molecules or atoms or electrons?

G O R T
2007-Oct-26, 11:02 AM
Both the Earth and the Sun generate magnetic fields using the Dynamo Theory. The Earth via movenent of molten metals, and the Sun via movement of conductive plasma cells.

Although Galaxies sustain some ephemeral plasma circulation which is thought to generate magnetic fields in thicker clouds, it is doubtfull that organized helical convective cells can exist in the galaxy as a whole. Atoms definately do not fit this billing, with subatomic particles little is known but this seems unlikely.

Tim Thompson
2007-Oct-26, 06:54 PM
... What I'm wondering is, is this something that only happens to stars and planets?
In the realm of astrophysics, it has only been observed in realtime for stars. Reversals of Earth's magnetic field are inferred from the geological record, although the evidence is very strong (see, i.e. Reversals of the Earth's Magnetic Field (http://www.amazon.com/Reversals-Earths-Magnetic-Field-Jacobs/dp/0521450721/ref=sr_1_1/000-8089485-2530421?ie=UTF8&s=books&qid=1193423909&sr=1-1), J.A. Jacobs, Cambridge University Press, 1992, 2nd ed).


What about galaxies?
No such reversals have been observed. It would probably not be possible to observe such a reversal in any case, just because of the long time scale. Our own Milky Way takes about 200,000,000 years to complete just one revolution, and surely any magnetic reversal, assuming that it is possible, must take at least that long to carry out. Our own sun takes about 167 revolutions on its axis in 11 years. If the galactic process is similar (a big if), then it would take 33.4 billion years for the Milky Way magnetic field to reverse itself. We might not notice that.


And what about smaller things, like say molecules or atoms or electrons?
That would be impossible. Their magnetic fields are fixed by their constituents, and cannot change without changing their basic structure. As GORT points out, stars and planets (and maybe galaxies as well) generate their magnetic fields by a dynamo, which is a fluid mechanical process. As the fluid flow changes, so does the magnetic field. That makes the magnetic field sensitive to the fluid state, and it can spontaneously reverse itself. That this is theoretically possible is well established (see, i.e. Glatzmaier & Roberts, 1995 (http://adsabs.harvard.edu/abs/1995Natur.377..203G); Roberts & Glatzmaier, 2000 (http://adsabs.harvard.edu/abs/2000RvMP...72.1081R); Glatzmaier, 2002 (http://adsabs.harvard.edu/abs/2002AREPS..30..237G)). And of course, we can see directly, in the case of the sun, that reversals do indeed happen.

korjik
2007-Oct-26, 07:40 PM
Isnt the 21cm line caused when the magnetic field of an electron switches direction from aligned with to aligned opposite to the proton magnetic field?

Swift
2007-Oct-26, 07:58 PM
Atoms don't flip their magnetic spin like a planet or star, where you look at the changed orientation versus their rotational spin or versus the physical surface of the planet (for example, the Earth's north magnetic pole is now in Antarctica.

But atoms can flip their spin orientation versus other atoms, for example, in a magnetic material (ferromagnetism (http://en.wikipedia.org/wiki/Ferromagnetism)) or versus an applied external magnetic field (Nuclear Magnetic Resonance (http://en.wikipedia.org/wiki/Nuclear_magnetic_resonance). But this is a rather different phenomenon than planetary magnetic fields.

Tim Thompson
2007-Oct-26, 08:22 PM
Isnt the 21cm line caused when the magnetic field of an electron switches direction from aligned with to aligned opposite to the proton magnetic field?
Yes, but that's easily explained by the electron physically flipping upside down. In the case of field reversals we are talking about, the field flips, but not the host (i.e., a star or planet or etc.).

Jens
2007-Oct-27, 06:48 AM
Yes, but that's easily explained by the electron physically flipping upside down. In the case of field reversals we are talking about, the field flips, but not the host (i.e., a star or planet or etc.).

Can we know that the host is flipping in the case of an electron, or do we just infer that it does?

EvilEye
2007-Oct-27, 09:28 PM
We know that atoms can line up with each other (as in Diamond), so flipping probably has less to do with pole-shifting than spin.