According to the LA Times scientists have created the lightest material on earth, called ultralight metallic microlattice, is it 99.9% air. To get this into perspective, Styrofoam is 100 times heavier.
This ultralight metallic microlattice is mainly made up from air, thanks to the microlattice cellular architecture.
Thomas Shandler of HRL Laboratories said “The trick is to fabricate a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair.”
Right now the team involved in the creation of the material are still determining the potential uses in the real world, but they are hinting that there may be potential for it in the aerospace industry and even with acoustic dampening or some battery applications.
Kitguru says: According to the reports, it floats down when dropped and the terminal velocity depends on the density.
So they have created mithril?
http://en.wikipedia.org/wiki/Mithril