Notice this was all resolved using calculations and computers. Now we need not worry making materials that do not conform to physical law. ;-)
Harry On Fri, Dec 30, 2011 at 4:49 PM, Mark Iverson-ZeroPoint <zeropo...@charter.net> wrote: > FYI: just a heads-up for the theorists in the group… > > -Mark > > > > Collaboration Resolves Century-Long Debate Over How to Describe > Electromagnetic Momentum Density in Matter > > December 28, 2011 > > > > Researchers from the NIST Center for Nanoscale Science and Technology and > the University of British Columbia have shown that the interaction between a > light pulse and a light-absorbing object, including the momentum transfer > and resulting movement of the object, can be calculated for any positive > index of refraction using a few, well-established physical principles > combined with a new model for mass transfer from light to matter.* This > work creates a foundation for understanding light absorption in > metamaterials, artificially tailored materials of intense interest in > nanophotonics and microwave engineering that can have negative indices of > refraction, and have potential applications in high resolution imaging, > lithography, optical sensing, high gain antennas, and stealth radar > coatings. > > > > Light carries momentum and can transfer momentum to matter via radiation > pressure. However, for the past century, there has been an ongoing debate > over the correct form of the electromagnetic momentum density in matter. In > the “Minkowski formulation,” the momentum density is proportional to the > index of refraction; in direct contrast, the “Abraham formulation” finds it > to be inversely proportional. While light is known to carry mass, a > detailed model for mass transfer from light to a medium that absorbs light > had not been formulated to date. The researchers propose a set of > postulates for light-matter interaction that encompass: a) the Maxwell > equations, which govern classical electromagnetic behavior; b) a generalized > Lorentz force law, which describes the force felt by matter in the presence > of an electromagnetic field; c) a model for electromagnetic mass density > transfer to an absorbing medium; and d) the Abraham formulation of momentum > density. Using both closed-form calculations and numerical simulations of > the interaction between an electromagnetic pulse and a test slab, the > researchers demonstrated that their postulates yield results that are > consistent with conservation of energy, mass, momentum, and center-of-mass > velocity at all times. They further showed that satisfaction of the last two > conservation laws unambiguously identifies the Abraham form as the true form > of momentum density in a positive-index medium. In addition to the > theoretical significance of these results and the implications for > metamaterials, the results will enable more accurate modeling of > light-matter interaction at the nanoscale and open new routes to optical > control of nano-mechanical systems incorporating light absorbing materials. > >
