Almost two decades ago in a test on electrodynamics, I was asked to re-derive the fundamental equations of electromagnetism (the Maxwell Equations) with the assumption that magnetic monopoles existed.
What the heck am I talking about here? Well, most people are familiar with the two types of charge that exist in the universe, positive and negative charge, and that there are fundamental units of this charge, protons for positive charge and electrons for negative charge (and yes, I am skipping those interesting but baffling to the majority quarks because they do not pertain to this discussion, if you want to discuss them, email me or go to the Physics department at your local university). Similar fundamental units of magnetisms do not exist; there are no “north monopoles” or “south monopoles” to complement the protons and electrons.
In my exam, based upon a few fundamental assumptions, that monopoles of both varieties existed and that there was a continuity of magnetic charge just as exists for electric charge, I was to derive the form the Maxwell Equations would take and explain the physical consequences of the new equations. At the time, I speculated that if there were such a thing as negative mass, something similar to the Maxwell Equations could be derived for gravity, and that there should therefore exist an equivalent of “gravomagnetics” with similar behaviors due to moving mass as there are because of the magnetic fields generated from moving charges. Needless tosay, I did not include these idle thoughts in my answer to the question, and admittedly it was not the best use of my effort during the exam, but the question was actually pretty straightforward so I did have the spare time.
While a “negative mass” has not been discovered, a recent measurement seems to point towards a possible derivation of a quantum theory of gravity, which has eluded Physicists for decades:
Scientists funded by the European Space Agency have measured the gravitational equivalent of a magnetic field for the first time in a laboratory. Under certain special conditions the effect is much larger than expected from general relativity and could help physicists to make a significant step towards the long-sought-after quantum theory of gravity.
Just as a moving electrical charge creates a magnetic field, so a moving mass generates a gravitomagnetic field. According to Einstein’s Theory of General Relativity, the effect is virtually negligible. However, Martin Tajmar, ARC Seibersdorf Research GmbH, Austria; Clovis de Matos, ESA-HQ, Paris; and colleagues have measured the effect in a laboratory.
I need to read the original paper, but based upon what is written in the article linked, this is pretty damn exciting to a real Physics geek like me. Although this result is not exactly what my speculations led to, it is gratifying to know that back when I was in graduate school even my idle speculations while working out an exam problem had merit and were not completely off base.
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