Why does the Earth have a magnetic field ?
Posted on Thursday, 3 January, 2013 | 6 comments
Columnist: William B Stoecker
The Earth’s magnetic field makes compasses function and shields us from dangerous solar radiation. Yet we don’t really know what produces it, and there are many, many aspects of it which are a complete mystery. The magnetic poles do not line up exactly with the spin axis and they are not exactly 180 degrees apart. Furthermore, they wander, and the rate of movement has increased markedly in recent decades. Periodically, at intervals of many hundreds of thousands of years apart, the Earth’s magnetic field weakens, dies out, and then reforms... with the magnetic poles reversed. No one knows why, and the field is currently getting weaker and weaker. We are told by establishment scientists that the field is produced by electrical currents in our planet’s nickel-iron core, and that the currents are produced by the planet’s rotation within the field, rather like the alternator in your car. In other words, the current produces the field, and the field produces the current... but how did it all begin? This is nothing more than a theory, but it is commonly presented as fact. It fails utterly to explain why the planet Jupiter, with, at most, a very small nickel iron core and a deep interior probably composed of metallic hydrogen also has a magnetic field. The Sun’s core is composed of super-heated plasma, mostly hydrogen and helium, and it has a magnetic field. Neutron stars are made of, as the name says, nothing but neutrons, and yet they have intense fields. Black holes are no longer made of matter at all as we understand it, yet they, too, have magnetic fields. Isn’t it likely that all of these fields have some common explanation? I noticed long ago that there is at least a rough correlation between a celestial body’s angular momentum and the strength of its field, but is the correlation exact and does it apply in every case? Could this be a clue as to the origin of these fields?
Momentum is mass times velocity. Two objects with the same mass and velocity will have the same momentum, but if one has a higher velocity or is more massive but has the same or a higher velocity it will have more momentum. Angular momentum is produced by spinning masses, and bear in mind that the velocity of, say, a spinning cylinder is low at the center and high at the rim. Nevertheless, the angular momentum of a spinning cylinder of uniform density is fairly easy to calculate. But for a sphere things become much more complex, beyond the abilities of most of us laymen to figure out, especially if, like all massive celestial bodies (and especially those composed mostly of gas or plasma) the object is more dense toward the center. Add to that the fact that there are different ways of measuring field strength, and we must consider its intensity at any one point (and this typically varies a good deal, especially between the equator and the poles) and how large it is, and how far out it extends. But if we are attempting to compare the angular momentum of roughly spherical objects we need not be able to compute the momentum of any of them. They will vary directly in proportion to their mass and equatorial surface velocity, so we can easily arrive at an approximate ratio.
Earth has a mass of 5.9X10 to the 24 power kilograms and an equatorial velocity of 1674.4 kilometers per hour, and I will define its angular momentum as one. Its field intensity is one half of one gauss. The planet Mercury has a mass of .055 that of Earth and an equatorial velocity of .0065 ours, giving it angular momentum equal to .00035 “Earth units.” But its field is .011 of Earth’s, so we see here only the very roughest correlation... all we can fairly say is that Mercury has less momentum and a weaker field. Venus has a mass equal to .815 of Earth’s and an equatorial surface velocity equal to .0038 of ours, giving it an angular momentum of .0031 Earth units, and its magnetic field is virtually nonexistent. Mars’ angular momentum is .0555 Earth’s, yet it, too, has virtually no magnetic field. Massive and rapidly spinning Jupiter has 8597 times Earth’s momentum , and, depending on how its field is measured, has anywhere from 1219 to 20,000 times ours... you see the difficulty here, when there is not even one universally-agreed upon definition of overall field strength. Saturn has 1988.96 times Earth’s angular momentum but its magnetic field is actually slightly weaker than ours. Uranus also has more momentum than our planet has, but a slightly weaker field. Neptune has 98.766 times our momentum and a field equal to 27 times the Earth’s. The Sun has 1,416,847.8 times Earth’s angular momentum, but its magnetic field, depending on how it is measured, is only 100 times ours, or, taking its average field intensity as 50 gauss and comparing surface areas of the Sun and Earth, 1,200,000 times ours, which is closer to the momentum ratio. And our own Moon has .00012 our momentum and no measurable magnetic field.
Obviously, a big part of the difficulty in making comparisons is the lack of agreement on how to measure overall field strength. Just as obviously, no matter how the fields are measured, Saturn and Uranus are a complete exception to my “rule” that momentum and field are always correlated, and the same is true of Mercury compared to Venus. The other celestial bodies appear to support at best only an approximate correlation.
So if, as I strongly suspect, there is some common cause for all the fields and it is something other than electrical currents in their cores (how do you have currents in collapsed neutron matter or in a black hole?) we must look for an explanation. Angular momentum certainly has some connection to it, but obviously it is not a direct one. Perhaps the explanation lies in something as simple as a net electric charge. On the face of it, there is no reason to believe that the Earth, for example, is electrically neutral, and if it has a net charge it would, as it spins on its axis, produce a magnetic field. If the field intensity, perhaps concentrated mostly on or near the surface, varied a bit in different regions, it would explain the offset and wandering magnetic poles. Perhaps the impacts of asteroids or comets with powerful charges opposite that of the Earth might wipe out our net charge and leave us with no field, but there is no evidence to support this, and what would reestablish our charge and our field?
Proponents of man-caused global warming are fond of saying that the “science is settled” and “the debate is over,” but science is never settled and the debates never end... nor should they. The existence of these magnetic fields may be a clue that could help someone qualified to do so develop an entirely new paradigm in physics. And I suspect that such a paradigm shift is long overdue.Article Copyright© William B Stoecker - reproduced with permission.