Exploring things pictorially helps to understand magnetism
The Basics and the Why of Magnetic Reversals
The earth's geomagetosphere is is currently undergoing a chaotic reversal. The reasons for this are rooted in the earth's core and in the differential rotation of the core to the outer layers and something called magnetic hysteresis, or a sudden reversal. In the case of the earth, it is not sudden in our sense of time, but in geologic time, it is in an instant. Magnetism, like electrical charge is rooted in the quantum and the quantum as can be easily demonstrated is discreet in nature. This understanding goes a long way to explaining the nature of magnetism.
The magnetic field is related to electrical force in a right angled relation as was experimentally determined by Faraday and Maxwell. It is by understanding this relationship that has allowed us to develop the various ways and means to generate both electrical and magnetic energy. It also dissipates in an inverse relation to distance from the source. As electrical force propagates at the velocity of light, so too does the magnetic field due to its relation to electrical force. Faraday by his experiments revealed the law of induction that is what we use to run transformers generators, and fully electrical motors. At the same time, Joseph Henry experimentally found the same principle in August 1831. They also found that moving a permanent magnet at right angles to a closed circuit generated an electric current as long as the magnet is in motion. Thus the foundation was laid for the electrical age that would inspire the likes of Tesla, Edison, Westinghouse and Einstein. Maxwell on the other hand, was able to codify these ideas that Faraday found by experiment in four founding partial differential equations the described the electromagnetic field. These were some of the ideas that Einstein would pick up and develop further to describe the photoelectric effect and eventually relativity.
Though electrical force can be accumulated via a monopole charge, we have as yet to isolate a thus far, theoretical magnetic monopole. Thus the magnetic field always has a dipole moment, which is to say, it has what we call a north and a south pole. That finding is a hangover from early sea faring days when it was found that a lodestone or a magnetic needle would always point north-south and serve as a guide to sailors. This use of magnetism precedes Faraday and Maxwell by several centuries, though no one knew about induction for the extent of that period. All magnetism is generated by either by the atomic means, electrical induction or by differential rotation of fluid or plasma layers or regions or a combination of all of these.
Magnetic fields may be scrambled into chaos, but there is always a dipole. This dipole allows magnetic fields to align and “self organize” under the right circumstances. According to observations that are born out in geology, molten materials can be magnetized by induction provided the the induction is continuous and the molten material cools slowly. Just about any material can be “magnetized” as long as most of it is “ferrous” or capable of accepting a magnetic charge by induction. Some materials, such as hydrogen, copper and oxygen are actually anti-magnetic and behave differently than nickel, iron and cobalt within a magnetic field. The earth shows in its magnetic geology, many periods of field reversal, one of which we are now experiencing. This too will be recorded in cooling molten rocks such as in tectonic plate boundaries undergoing spreading and in shield volcanoes such as Hawaii. We have found with spreading regions that the earth has been through dozens of magnetic flips in the past. There is a chaotic cycle involved that does not seen to focus on a periodic rotation. Some fields are long lived such as the current one of the recent past that is now ending. Some are short, lasting only a few thousand years before flipping back.
All elements are either magnetically attractive or diamagnetic or repulsive. Each one will react to a greater or lesser extent to a magnetic field. We know that iron reacts strongly to a magnetic field, whereas aluminum reacts by becoming a magnetic reflector and creating a repulsive force. Though all one has to do is move a magnet toward iron to attract if, a stationary magnet will only generate a local reflection in aluminium that will not cause any further repulsion. In that case, the magnet has to be under motion in order to increase the reflectivity, which is the principle behind linear induction motors based on aluminum reflectors. The important idea behind variable magnetic reaction is important in one consideration as far as the earth is concerned and that is the fact that the magnetic field is split into field lines. We have learned that the more intense the magnetic field is, the more it will split into lines of force that loop between regional dipoles. The magnetic field becomes increasingly fractured according to increasing field strength in a magnetic fractal. We can actually see this principle in action on the sun where diamagnetic hydrogen ions get caught between magnetic field lines. This can be seen on earth as well if we know how and where to look and that place is in the aurora that divide into shimmering sheets composed of closely placed lines in the really clear cases.
Magnets that we deal with have a point where they will collapse and reverse and that is called the hysteresis, or the moment of field flip. This can be caused by an internal force or by a stronger external force. Some theorists think that the heliomagnetosphere is responsible for the flipping of the geomagnetosphere, but since the sun's field flips on an average 11.2 year cycle and the earth's does not, we have to look elsewhere for the main driver. As it turns out and is increasingly born out by observation and experiment, that source is inside the earth itself. As far as we know, the earth has always had a magnetic field as it is a dynamic planet. Mercury also has a magnetic field, but Venus according to our most recent observations, lacks one for some unknown reason. The earth as we have come to know it, has several layers that are not constructed like the simple “onion layer” idea that once prevailed. Inside the earth there are surprisingly fast plumes that rise from the very center. These drive local variations in the magnetic field as well as tectonic motion and volcanic activity. It is also known that the main field is generated due to the slightly faster rotation of the inner part of the earth relative to the outer regions out to the crust.
One idea about field reversal comes from the winding of the main field like what occurs in the sun due to its differential rotation. At a certain point, the field snaps and reverses. This may account for earthquake storms, just as field collapse on the sun results in a coronal discharge into space. Another comes from the nature of the core of the earth, which is essentially a mass of molten uranium in a continuous state of meltdown. As radioactive decay occurs in a combined an uneven manner, parts of the exhausted uranium core cool slightly, causing a chaotic mixing of the hot and cool parts. This mixing triggers a magnetic chaos that then attempts to reorient according to the principles of magnetic induction and self organization.
All magnetic phenomena are ultimately based on the quantum events of atoms and ions of all types. This is why the magnetic field is discreet and readily self organizes into a dipole when conditions are right. As the earth behaves like a great electromagnet due to changes ongoing within, aperiodic reversals are actually the norm and not the exception as vindicated in magnetic geological history. As of this time, the earths familiar field is collapsing into the inter-period chaos before self organizing to its opposite orientation.
Resources on the Geomagnetosphere
Origins of the Geomagnetosphere
Effects of Geomagnetic Chaos on Migratory Species
- Effects of Geomagnetic Chaos on Migratory Species
Surprisingly fast changes in the earth's core are driving geomagnetic reversal and is having many ramifications upon the surface of the earth. Geomagnetic reversal is not just inconvenient to boy scouts...