Produced by extracting the liquid component of a gel through supercritical drying, Aerogel is officially the world’s lightest solid. Since this synthetic porous ultralight material is derived from a gel, in which the liquid component for the gel has been replaced with a gas, it becomes a solid with extremely low density and low thermal conductivity. It’s 99.8% air, and features a porous solid network that contains air pockets, with the air pockets taking up the majority of space within the material, making it near weightless. Read more for an in-depth video and additional information.
Aerogels are great thermal insulators because they almost cancel two of the three methods of heat transfer – conduction (they are mostly composed of insulating gas) and convection (the microstructure prevents net gas movement). They are also incredible conductive insulators due to being composed almost entirely of gases, which are very poor heat conductors. The ghostly color they do have is caused by Rayleigh scattering of the shorter wavelengths of visible light by the nano-sized dendritic structure, making it appear smoky blue against dark backgrounds and yellowish against bright backgrounds.