Abraham-Minkowski controversy
- Abraham-Minkowski controversy
The Abraham-Minkowski controversy is a physics debate concerning electromagnetic momentum within dielectric media. The preponderance of evidence in the debate suggests that the Abraham equation is correct [Quantum vacuum contribution to the momentum of dielectric media, A. Feigel, PHYSICAL REVIEW LETTERS 92 (2): Art. No. 020404 JAN 16 2004] , but some investigators disagree.
Two equations exist describing momentum transfer between matter and electromagnetic fields. Both seem to be supported by contradicting experimental data. The two existing equations were first suggested by Max Abraham and Hermann Minkowski, from which the controversy name derives. Both define the momentum of an electromagnetic field permeating matter. Abraham's equation suggests that in materials through which light travels more slowly, electromagnetic fields should have lower momentum, while Minkowski suggests it should have a greater momentum. Minkowski suggested that Abraham only accounted for the momentum of the electromagnetic fields, and his equation was an attempt to take into account the momentum of the material as well. More recent work suggests that this characterization is incorrect.
At least one report has suggested Minkowski's formulation, if correct, would provide the physical base for reactionless drive [ [http://www.intalek.com/Index/Projects/Research/0994.pdf Propellantless Propulsion by Electromagnetic Inertia Manipulation: Theory and Experiment] " by Hector Hugo Brito] . However, an independent review from the Air Force Academy concluded that there would be no expected net propulsive forces, and a NASA report determined that "The signal levels are not sufficiently above the noise as to be conclusive proof of a propulsiveeffect." [ [http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?2004/TM-2004-213082.html NASA and DoD Report on Prospects for Breakthrough Propulsion From Physics] ]
The two equations for the momentum in a dielectric with refractive index n are:
*The Minkowski version is: nhf/c
*The Abraham version is: hf/(nc)
where h is the Planck constant, f is the frequency of the light and c is the speed of light in vacuum.
ee also
References
External links
* [http://focus.aps.org/story/v13/st3 Article in Physical Review Focus]
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