"Reconnection" of magnetic field lines

[rumborak]

This is a bit vague, but I remember reading that during stuff like coronal ejections, magnetic field lines "reconnect". Now, does that not suppose "loose" magnet lines in the process? Which to my understanding do not exist?

 

[jerromyjon]

The field lines are never broken, It's the plasma being ejected from the surface, which gets drawn back and reconnects with the surface forming an "iron filing" type visualization of the magnetic field.

 

[stedwards]

On one program on the SCI channel, magnetic field lines arcing from the sun were said to "cross". This is the caliber of material you can expect from public entertainment.

 

[rumborak]

The field lines are never broken, It's the plasma being ejected from the surface, which gets drawn back and reconnects with the surface forming an "iron filing" type visualization of the magnetic field.

Thing is, and this actually applies to the concept of magnetic field lines overall, I have a hard time imagining a smooth transformation that transforms two separate magnetic fields into one combined one.
I mean, even for the simplest example where you have two bar magnets, like this:

Now, those two magnets, when they were spaced very fast apart, had all their own field lines terminate back into themselves again. Now, when they were brought closer to each other, field like after field line must have switched at some point to now go into the other bar magnet.

Is this a case of "magnetic field lines are a neat visualization, but that's the limit of their applicability"?
Are magnetic field lines kinda like isolines in topographic maps in that their path simply traces something of constant value? (and just like a river suddenly drastically changing path because a small local value has changed)

 

[jerromyjon]

The "field lines" themselves don't exist in reality, there is simply a field density at any given point. When you start to draw lines between points it never exactly matches the true nature of the fluidity of the interaction of fields.

 

[rumborak]

Yeah, at this point I kinda figured.

Do they actually have any kind of formal definition? Are they just "smooth lines perpendicular to field isolines"?

 

[jerromyjon]

"smooth lines perpendicular to field isolines

Forget lines and visualize that picture as a topological map...

 

[rumborak]

Well, that's why I'm saying perpendicular. The field strength isolines (I.e. the " topo map") would surround the magnet, not go through it.

 

[jerromyjon]

Field vector?

 

[rumborak]

I was thinking about the field vector, yeah. I guess the field lines are just connected field vectors? I.e. the flight path a massless charged particle (if such a thing existed) would trace.
Which of course would then also explain the "reconnection" part, which really just means that a local change in the field causes the field lines to trace differently.

 

[jerromyjon]

The field lines are uniform vector potentials.