Speaking of loss of “gravitational mass” the electrons in graphene are called massless.
One of the most controversial and defining properties is indeed an “apparent loss of mass” which aside from semantics, is interesting for a number of practical reasons in batteries and capacitors. https://www.nature.com/articles/nature04233 https://phys.org/news/2017-08-electrons-liquid-graphene-physics.html Side note: the first article was written by the Russians who won the Nobel Prize in physics in 2010 for the discovery of graphene These Dirac electrons have a linear dispersion, as if they have zero mass, and very high mobility. Of course they must possess mass of a kind, but act like photons and follow the same equation as massless particles that travel at C, so you would expect some of the same qualitative behavior as photons. But they are not moving fully at the speed of light, and they are not really massless (despite some bad reporting). However, they can turn graphene into a superconductor… and much more. The understanding and use of Dirac electrons may be the hottest research topic in physics in 2018 especially if a high temperature superconductive version of graphene is found which exploits Dirac electron. This is a prediction… and another is that the Dirac electron will be shown to provide the negative charge in UDH – ultra dense hydrogen. (using a hybrid deep electron theory which borrows from Holmlid, Lawandy, Mills, Meulenberg, etc). Jones
