Joined at the Hip: Magnetic Fields and Electricity

Hello world. I'm here and this is my obligatory first post! I must here recount my primary exegesis on the relationship between electricity and magnetism. Hopefully you will read and enjoy it before moving on to reading any of my other posts. 

I will, throughout this post, refer to the words of others who have summarized the currently accepted views on classical electrodynamics. Thus, I do not consider the majority of this post to be 'original research,' merely a collated regurgitation of well-stated facts.

Hopefully, by the end of this post, you will believe this simple thesis, as I do: electric currents are the sole source of magnetic fields in the universe.

It seems an outrageously simple statement. Can it be true? Put simply, yes.

For the first and simplest statement of fact, we'll turn to the Hyperphysics site:

"Magnetic fields are produced by electric currents, which can be macroscopic currents in wires, or microscopic currents associated with electrons in atomic orbits."
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfie.html

This is an extraordinarily simple and factual statement. Magnetic fields are produced by electric currents. These can be macroscopic currents in wires or these can be atomic-scale currents where the net collective motion of the electrons around the nuclei of atoms constitutes the 'electric current' (this is relevant primarily for the explanation of 'permanent' magnetism, as in bar magnets or horseshoe magnets).

But, is it correct? Do electric currents produce magnetic fields? Even at the atomic scale?

Let us first consider the general case and then come back to atomic scales and 'permanent' magnets.

Wikipedia seems to be in basic agreement with this non-controversial assessment:

"Electric current [I, above] produces a magnetic field [B, above]. The magnetic field can be visualized as a pattern of circular field lines surrounding the wire."
http://en.wikipedia.org/wiki/Electric_current#Electromagnetism

Expanding on this concept incrementally, one can also relate electric currents and magnetic fields to electric fields:

"An electromagnetic field (also EMF or EM field) is a physical field produced by moving electrically charged objects. ... The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field."
http://en.wikipedia.org/wiki/Electromagnetic_field

The World Health Organization offers a similar explanation:

"Electric fields are created by differences in voltage: the higher the voltage, the stronger will be the resultant field. Magnetic fields are created when electric current flows: the greater the current, the stronger the magnetic field. An electric field will exist even when there is no current flowing. If current does flow, the strength of the magnetic field will vary with power consumption but the electric field strength will be constant."

"Magnetic fields are created only when the electric current flows."
http://www.who.int/peh-emf/about/WhatisEMF/en/

So, what can we take away from all this? I'll let Richard Fitzpatrick of the University of Texas at Austin summarize it thus (from a course on classical electromagnetism):

"...steady electric and magnetic fields cannot generate themselves. Instead, they have to be generated by stationary charges and steady currents. So, if we come across a steady electric field we know that if we trace the field-lines back we shall eventually find a charge. Likewise, a steady magnetic field implies that there is a steady current flowing somewhere. All of these results follow from vector field theory (i.e., from the general properties of fields in three-dimensional space), prior to any investigation of electromagnetism."
http://farside.ph.utexas.edu/teaching/em/lectures/node37.html

Electric fields originate at one or more charged particles. Electric currents (the net motion of like-charged particles in the same direction or of oppositely charged particles in opposite directions) generate magnetic fields.

A little bit of history from NASA physicists Dr. David P. Stern and Dr. Mauricio Peredo may put these statements into perspective:

"People not familiar with magnetism often view it as a somewhat mysterious property of specially treated iron or steel."

"Out in space there is no magnetic iron, yet magnetism is widespread. For instance, sunspots consist of glowing hot gas, yet they are all intensely magnetic."

"It is all related to electricity."

"Close to 1800 it was found that when the ends of a chemical "battery" were connected by a metal wire, a steady stream of electric charges flowed in that wire and heated it. That flow became known as an electric current. In a simplified view, what happens is that electrons hop from atom to atom in the metal."

"In 1821 Hans Christian Oersted in Denmark found, unexpectedly, that such an electric current caused a compass needle to move. An electric current produced a magnetic force!"

"Andre-Marie Ampère in France soon unraveled the meaning. The fundamental nature of magnetism was not associated with magnetic poles or iron magnets, but with electric currents. The magnetic force was basically a force between electric currents."

"--Two parallel currents in the same direction attract each other.
--Two parallel currents in opposite directions repel each other."

"Here is how this can lead to the notion of magnetic poles. Bend the wires into circles with constant separation:"

"--Two circular currents in the same direction attract each other.
--Two circular currents in opposite directions repel each other."
http://www-istp.gsfc.nasa.gov/Education/wmfield.html

So, at its simplest, the 'magnetic field' is actually a force felt between electric currents. Electric currents are the source of the magnetic field. The stronger an electric current the stronger its associated magnetic field (or, put another way, the stronger the force felt by another electric current some finite distance away).

But, "what of 'permanent magnets'?" you ask. No measurable current flows along the length of a bar magnet. Certainly this explanation must be false if a magnetic field can be generated without a current flow!

Well, not exactly. It is true that there are no currents flowing from one end of the bar magnet to the other. However, each atom can be considered to constitute its own electric current which generates an associated magnetic field:

"...[according to] the Ampère model, ... all magnetization is due to the effect of microscopic, or atomic, circular bound currents, also called Ampèrian currents, throughout the material. For a uniformly magnetized cylindrical bar magnet, the net effect of the microscopic bound currents is to make the magnet behave as if there is a macroscopic sheet of electric current flowing around the surface, with local flow direction normal to the cylinder axis."
http://en.wikipedia.org/wiki/Ampere_model#Amp.C3.A8re_model

In short, the adjacent portion of currents flowing in the same direction cancel. So, the entire volume inside a magnet effectively cancels mathematically in terms of currents. However, for the outside layer of atoms in the magnet, there are no adjacent currents external to the magnet to cancel them and the magnet as a whole acts as if there is a sheet of current flowing there.

We can return to Richard Fitzpatrick's course on Classical Electrodynamics for an illustration of this idea:

"...atoms consist of negatively charged electrons in orbit around positively charged nuclei. A moving electric charge constitutes an electric current, so there must be a current associated with every electron in an atom. In most atoms, these currents cancel one another out, so that the atom carries zero net current. However, in the atoms of ferromagnetic materials (i.e., iron, cobalt, and nickel) this cancellation is not complete, so these atoms do carry a net current. Usually, the atomic currents are all jumbled up (i.e., they are not aligned in any particular plane) so that they average to zero on a macroscopic scale. However, if a ferromagnetic material is placed in a strong magnetic field then the currents circulating in each atom become aligned such that they flow predominately in the plane perpendicular to the field. In this situation, the currents can combine together to form a macroscopic magnetic field which reinforces the alignment field. In some ferromagnetic materials, the atomic currents remain aligned after the alignment field is switched off, so the macroscopic field generated by these currents also remains. We call such materials permanent magnets."
http://farside.ph.utexas.edu/teaching/302l/lectures/node77.html

So, it seems that so-called 'permanent magnets' are merely a special case wherein tiny electric currents at the atomic level add up to an apparent macroscopic magnetic field. So long as the majority of those individual magnetic domains remain aligned, as they do in ferromagnets (metallic permanent magnets), the macroscopic field will persist.

I believe it is not safe to come to our concluding remarks on the subject of the relationship between electricity and magnetism.

Drs. Stern and Peredo conclude their historical piece on magnetic fields succinctly thus:

"In space, on the Sun and in the Earth's core, electric currents are the only source of magnetism." (Emphasis added.)
http://www-istp.gsfc.nasa.gov/Education/wmfield.html

Professor Richard Fitzpatrick similarly concludes his lecture on why magnetic monopoles do not exist:

"In conclusion, all steady magnetic fields in the Universe are generated by circulating electric currents of some description."
http://farside.ph.utexas.edu/teaching/em/lectures/node35.html

Fitzpatrick further concludes his lecture on the origin of permanent magnetism thus:

"In conclusion, all magnetic fields encountered in nature are generated by circulating currents. There is no fundamental difference between the fields generated by permanent magnets and those generated by currents flowing around conventional electric circuits. In the former, case the currents which generate the fields circulate on the atomic scale, whereas, in the latter case, the currents circulate on a macroscopic scale (i.e., the scale of the circuit)."
http://farside.ph.utexas.edu/teaching/302l/lectures/node77.html

Hopefully, at this juncture we have all arrived together at the same non-controversial conclusion. That is to say, the outrageously simple thesis proffered at the outset is in fact correct:

Electric currents are the sole source of magnetic fields in the universe.

This extremely simple understanding forms the basis of this blog. It is here suggested that this basic premise can be used to reverse engineer a new emergent understanding of our universe.

"How so?" you might ask...

Wikipedia, while an imperfect resource, occasionally offers a few salient nuggets, such as this one:

"Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient. Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current."
http://en.wikipedia.org/wiki/Electric_current#Electromagnetism

Why is this important? Well, consider the above statement. If we understand that electric currents generate magnetic fields, that also allows us an avenue of inquiry. If we see a magnetic field but the electric current is inconvenient or impossible to get to, we may examine the characteristics of the magnetic field and work backward to determine characteristics of the electric current that must by definition also be present to drive the observed magnetic field.

So, why is that important with respect to understanding the universe? 

My, my! Quite a lot of questions you've got there... Okay, I'll tell you why this is important. 

Being perfectly frank, everywhere we look in space, it is permeated by large-scale magnetic fields. They have been implicated in everything from star birth to shaping molecular clouds. The earth has a magnetosphere and the solar magnetic field flips every 11 years for reasons heretofore not well understood. Even so-called extremely 'young' galaxies can be permeated by strong magnetic fields.

In point of fact, there is so much 'magnetism' out there that it has led prominent institutions to declare that we live in a 'Magnetic Universe!' However, the source of magnetic fields seem to have eluded researchers and astronomers appear to have thrown up their collective hands in confusion...

"...we now appreciate that understanding the cosmos is impossible without understanding magnetism. [Magnetic fields] play a vital role in key physical processes throughout the universe, from the formation of stars to the evolution of entire galaxies. "

"On the largest scales, much of the universe's mass consists of charged particles, whose movements are completely enslaved by whatever magnetism surrounds them." (Emphasis added.)

"...on the scale of entire clusters of galaxies, only rough measurements of magnetism have so far been made ... on the very largest scales, there have been tentative reports that the entire universe is magnetised."

"Underpinning all this is a serious problem: we simply don't know what created this cosmic magnetism, or how it has maintained its strength over billions of years."
http://www.cosmosmagazine.com/features/online/4248/the-magnetic-universe

Being blunt for a moment now, if we live in a 'Magnetic Universe' it can be just as easily said that we live in an 'Electric Universe,' keeping in mind that we have reached the point in the curriculum where we should all be on the same page. Electric currents drive magnetic fields.

Where we see all-pervasive large-scale magnetic fields, we should now know that we can reason our way backward and come to the justifiable conclusion that large-scale electric currents must, by definition, also be just as all-pervasive. We can't have one without the other... Large-scale magnetic fields are diagnostic for large-scale electric currents. As electric currents produce magnetic fields, any magnetic fields we observe must be produced by electric currents. 

It is now incumbent upon astronomy to acknowledge this outrageously simple fact and moreover to consistently apply it to the cosmos. Do I believe it is possible probe the far reaches of the universe to determine whether such currents exist? Yes, unequivocally, though by indirect methods since we cannot physically travel to said far reaches.

I submit as a proof of concept this recent news item predicated on research submitted by radio astronomers to arxiv:

"Researchers at the University of Toronto have found some serious current emanating from a huge cosmic jet 2 billion light years from Earth. At 10^18 amps, the current is the strongest current ever seen, equaling something like a trillion bolts of lightning."
http://www.popsci.com/technology/article/2011-06/strongest-current-universe-detected-some-2-billion-light-years-away

It is clear that cosmic-scale electric currents *do* exist. It is equally clear that they must give rise to magnetic fields.

Certainly, we cannot physically reach the cosmic electric currents themselves with our current level of technology. They are too far away.

However, we can study the magnetic fields we observe out in space in order to intuit the characterization of those electric currents (e.g., using such known concepts as Faraday rotation or the Zeeman effect). For closer objects like the Sun, the Stark effect can give us information about electric fields thereabouts. However, my understanding is that, for objects far out in the cosmos, our ability to resolve fine detail may be insufficient to effectively utilize that effect, which is unfortunate. Sometimes we must make do with the tools we have that do work.

Magnetic fields can be observed far more easily with existing tools than electric currents can (so it is not entirely surprising that the field of astronomy has preferred to speak in terms of magnetism rather than electricity). But, as the above demonstrates, it is entirely possible to make observations and formulate models consistent with an electrical model.

In some regards it simply boils down to metaphysics. Is the universe by and large a gravitational machine, in which case we exclude and safely ignore electrical interactions? Or does the universe also have an electrical character, in which case it would be a mistake to prematurely dismiss considering the implications of electrical interaction (especially since the raw electric force is 36 to 39 order of magnitude greater than the raw gravitational force)?

Clearly, if magnetic fields are pervasive (and they are), the universe must have an electrical character. Which character (gravitational or electrical) is dominant remains to be determined. But, the question is now begged and requires adequate redress from unbiased researchers.

Our universe is awash in plasma. Upward of 99% of the directly observable matter in the universe is in the plasma state. Plasma is a highly conductive medium (electric currents flow easily through it). To ignore the likelihood that electric currents flow in cosmic plasma, driving cosmic magnetic fields, would be foolhardy.

Hopefully I have long since made my case that this investigation is in fact warranted and worthwhile. If you wish to explore this new frontier with me, I hereby welcome you to the journey...